Solid-liquid surface tensions of critical nuclei and nucleation barriers from a phase-field-crystal study of a model binary alloy using finite system sizes.

PubMed

Choudhary, Muhammad Ajmal; Kundin, Julia; Emmerich, Heike; Oettel, Martin

2014-08-01

Phase-field-crystal (PFC) modeling has emerged as a computationally efficient tool to address crystal growth phenomena on atomistic length and diffusive time scales. We use a two-dimensional phase-field-crystal model for a binary system based on Elder et al. [Phys. Rev. B 75, 064107 (2007)] to study critical nuclei and their liquid-solid phase boundaries, in particular the nucleus size dependence of the liquid-solid interface tension as well as of the nucleation barrier. Critical nuclei are stabilized in finite systems of various sizes, however, the extracted interface tension as function of the nucleus radius r is independent of system size. We suggest a phenomenological expression to describe the dependence of the extracted interface tension on the nucleus radius r for the liquid-solid system. Moreover, the numerical PFC results show that this dependency can not be fully described by the nonclassical Tolman formula.

Phase III gross solids removal devices pilot study, 2002-2005.

DOT National Transportation Integrated Search

2005-12-01

The objective of the Phase III Gross Solids Removal Devices (GSRDs) Pilot study was to : evaluate the performance of non-proprietary devices that can capture gross solids and that can be : incorporated into existing highway drainage systems or implem...

Phase IV gross solids removal devices pilot study, 2004-2005.

DOT National Transportation Integrated Search

2005-12-01

The objective of the Phase IV Gross Solids Removal Device (GSRD) Pilot study was to evaluate : the performance of one non-proprietary device that can capture gross solids and that can be : incorporated into existing highway drainage systems or implem...

Microwave spectroscopic observation of distinct electron solid phases in wide quantum wells

NASA Astrophysics Data System (ADS)

Hatke, A. T.; Liu, Yang; Magill, B. A.; Moon, B. H.; Engel, L. W.; Shayegan, M.; Pfeiffer, L. N.; West, K. W.; Baldwin, K. W.

2014-06-01

In high magnetic fields, two-dimensional electron systems can form a number of phases in which interelectron repulsion plays the central role, since the kinetic energy is frozen out by Landau quantization. These phases include the well-known liquids of the fractional quantum Hall effect, as well as solid phases with broken spatial symmetry and crystalline order. Solids can occur at the low Landau-filling termination of the fractional quantum Hall effect series but also within integer quantum Hall effects. Here we present microwave spectroscopy studies of wide quantum wells that clearly reveal two distinct solid phases, hidden within what in d.c. transport would be the zero diagonal conductivity of an integer quantum-Hall-effect state. Explanation of these solids is not possible with the simple picture of a Wigner solid of ordinary (quasi) electrons or holes.

AUTOMATED SOLID PHASE EXTRACTION GC/MS FOR ANALYSIS OF SEMIVOLATILES IN WATER AND SEDIMENTS

EPA Science Inventory

Data is presented on the development of a new automated system combining solid phase extraction (SPE) with GC/MS spectrometry for the single-run analysis of water samples containing a broad range of organic compounds. The system uses commercially available automated in-line sampl...

Solid-solid collapse transition in a two dimensional model molecular system.

PubMed

Singh, Rakesh S; Bagchi, Biman

2013-11-21

Solid-solid collapse transition in open framework structures is ubiquitous in nature. The real difficulty in understanding detailed microscopic aspects of such transitions in molecular systems arises from the interplay between different energy and length scales involved in molecular systems, often mediated through a solvent. In this work we employ Monte-Carlo simulation to study the collapse transition in a model molecular system interacting via both isotropic as well as anisotropic interactions having different length and energy scales. The model we use is known as Mercedes-Benz (MB), which, for a specific set of parameters, sustains two solid phases: honeycomb and oblique. In order to study the temperature induced collapse transition, we start with a metastable honeycomb solid and induce transition by increasing temperature. High density oblique solid so formed has two characteristic length scales corresponding to isotropic and anisotropic parts of interaction potential. Contrary to the common belief and classical nucleation theory, interestingly, we find linear strip-like nucleating clusters having significantly different order and average coordination number than the bulk stable phase. In the early stage of growth, the cluster grows as a linear strip, followed by branched and ring-like strips. The geometry of growing cluster is a consequence of the delicate balance between two types of interactions, which enables the dominance of stabilizing energy over destabilizing surface energy. The nucleus of stable oblique phase is wetted by intermediate order particles, which minimizes the surface free energy. In the case of pressure induced transition at low temperature the collapsed state is a disordered solid. The disordered solid phase has diverse local quasi-stable structures along with oblique-solid like domains.

Solid-solid collapse transition in a two dimensional model molecular system

NASA Astrophysics Data System (ADS)

Singh, Rakesh S.; Bagchi, Biman

2013-11-01

Solid-solid collapse transition in open framework structures is ubiquitous in nature. The real difficulty in understanding detailed microscopic aspects of such transitions in molecular systems arises from the interplay between different energy and length scales involved in molecular systems, often mediated through a solvent. In this work we employ Monte-Carlo simulation to study the collapse transition in a model molecular system interacting via both isotropic as well as anisotropic interactions having different length and energy scales. The model we use is known as Mercedes-Benz (MB), which, for a specific set of parameters, sustains two solid phases: honeycomb and oblique. In order to study the temperature induced collapse transition, we start with a metastable honeycomb solid and induce transition by increasing temperature. High density oblique solid so formed has two characteristic length scales corresponding to isotropic and anisotropic parts of interaction potential. Contrary to the common belief and classical nucleation theory, interestingly, we find linear strip-like nucleating clusters having significantly different order and average coordination number than the bulk stable phase. In the early stage of growth, the cluster grows as a linear strip, followed by branched and ring-like strips. The geometry of growing cluster is a consequence of the delicate balance between two types of interactions, which enables the dominance of stabilizing energy over destabilizing surface energy. The nucleus of stable oblique phase is wetted by intermediate order particles, which minimizes the surface free energy. In the case of pressure induced transition at low temperature the collapsed state is a disordered solid. The disordered solid phase has diverse local quasi-stable structures along with oblique-solid like domains.

Further analytical study of hybrid rocket combustion

NASA Technical Reports Server (NTRS)

Hung, W. S. Y.; Chen, C. S.; Haviland, J. K.

1972-01-01

Analytical studies of the transient and steady-state combustion processes in a hybrid rocket system are discussed. The particular system chosen consists of a gaseous oxidizer flowing within a tube of solid fuel, resulting in a heterogeneous combustion. Finite rate chemical kinetics with appropriate reaction mechanisms were incorporated in the model. A temperature dependent Arrhenius type fuel surface regression rate equation was chosen for the current study. The governing mathematical equations employed for the reacting gas phase and for the solid phase are the general, two-dimensional, time-dependent conservation equations in a cylindrical coordinate system. Keeping the simplifying assumptions to a minimum, these basic equations were programmed for numerical computation, using two implicit finite-difference schemes, the Lax-Wendroff scheme for the gas phase, and, the Crank-Nicolson scheme for the solid phase.

Effects of gravity reduction on phase equilibria. Part 1: Unary and binary isostructural solids

NASA Technical Reports Server (NTRS)

Larson, D. J., Jr.

1975-01-01

Analysis of the Skylab II M553 Experiment samples resulted in the hypothesis that the reduced gravity environment was altering the melting and solidification reactions. A theoretical study was conducted to define the conditions under which such alteration of phase relations is feasible, determine whether it is restricted to space processing, and, if so, ascertain which alloy systems or phase reactions are most likely to demonstrate such effects. Phase equilibria of unary and binary systems with a single solid phase (unary and isomorphous) were considered.

Biological treatment of soils contaminated with hydrophobic organics using slurry- and solid-phase techniques

NASA Astrophysics Data System (ADS)

Cassidy, Daniel H.; Irvine, Robert L.

1995-10-01

Both slurry-phase and solid-phase bioremediation are effective ex situ soil decontamination methods. Slurrying is energy intensive relative to solid-phase treatment, but provides homogenization and uniform nutrient distribution. Limited contaminant bioavailability at concentrations above the required cleanup level reduces biodegradation rates and renders solid phase bioremediation more cost effective than complete treatment in a bio-slurry reactor. Slurrying followed by solid-phase bioremediation combines the advantages and minimizes the weaknesses of each treatment method when used alone. A biological treatment system consisting of slurrying followed by aeration in solid phase bioreactors was developed and tested in the laboratory using a silty clay loam contaminated with diesel fuel. The first set of experiments was designed to determine the impact of the water content and mixing time during slurrying on the rate an extent of contaminant removal in continuously aerated solid phase bioreactors. The second set of experiments compared the volatile and total diesel fuel removal in solid phase bioreactors using periodic and continuous aeration strategies. Results showed that slurrying for 1.5 hours at a water content less than saturation markedly increased the rate and extent of contaminant biodegradation in the solid phase bioreactors compared with soil having no slurry pretreatment. Slurrying the soil at or above its saturation moisture content resulted in lengthy dewatering times which prohibited aeration, thereby delaying the onset of biological treatment in the solid phase bioreactors. Results also showed that properly operated periodic aeration can provide less volatile contaminant removal and a grater fraction of biological contaminant removal than continuous aeration.

Split Flow Online Solid-Phase Extraction Coupled with Inductively Coupled Plasma Mass Spectrometry System for One-Shot Data Acquisition of Quantification and Recovery Efficiency.

PubMed

Furukawa, Makoto; Takagai, Yoshitaka

2016-10-04

Online solid-phase extraction (SPE) coupled with inductively coupled plasma mass spectrometry (ICPMS) is a useful tool in automatic sequential analysis. However, it cannot simultaneously quantify the analytical targets and their recovery percentages (R%) in one-shot samples. We propose a system that simultaneously acquires both data in a single sample injection. The main flowline of the online solid-phase extraction is divided into main and split flows. The split flow line (i.e., bypass line), which circumvents the SPE column, was placed on the main flow line. Under program-controlled switching of the automatic valve, the ICPMS sequentially measures the targets in a sample before and after column preconcentration and determines the target concentrations and the R% on the SPE column. This paper describes the system development and two demonstrations to exhibit the analytical significance, i.e., the ultratrace amounts of radioactive strontium ( 90 Sr) using commercial Sr-trap resin and multielement adsorbability on the SPE column. This system is applicable to other flow analyses and detectors in online solid phase extraction.

Efficient chemical potential evaluation with kinetic Monte Carlo method and non-uniform external potential: Lennard-Jones fluid, liquid, and solid

NASA Astrophysics Data System (ADS)

Ustinov, E. A.

2017-07-01

The aim of this paper is to present a method of a direct evaluation of the chemical potential of fluid, liquid, and solid with kinetic Monte Carlo simulation. The method is illustrated with the 12-6 Lennard-Jones (LJ) system over a wide range of density and temperature. A distinctive feature of the methodology used in the present study is imposing an external potential on the elongated simulation box to split the system into two equilibrium phases, one of which is substantially diluted. This technique provides a reliable direct evaluation of the chemical potential of the whole non-uniform system (including that of the uniformly distributed dense phase in the central zone of the box), which, for example, is impossible in simulation of the uniform crystalline phase. The parameters of the vapor-liquid, liquid-solid, and fluid-solid transitions have been reliably determined. The chemical potential and the pressure are defined as thermodynamically consistent functions of density and temperature separately for the liquid and the solid (FCC) phases. It has been shown that in two-phase systems separated by a flat interface, the crystal melting always occurs at equilibrium conditions. It is also proved that in the limit of zero temperature, the specific heat capacity of an LJ crystal at constant volume is exactly 3Rg (where Rg is the gas constant) without resorting to harmonic oscillators.

Biofuel production utilizing a dual-phase cultivation system with filamentous cyanobacteria.

PubMed

Aoki, Jinichi; Kawamata, Toru; Kodaka, Asuka; Minakawa, Masayuki; Imamura, Nobukazu; Tsuzuki, Mikio; Asayama, Munehiko

2018-04-17

Biomass yields and biofuel production were examined in a dual (solid and liquid)-phase cultivation system (DuPHA) with the unique filamentous cyanobacteria, Pseudanabaena sp. ABRG 5-3 and Limnothrix sp. SK1-2-1. Continuous circular cultivation was driven under the indoor closed (IC) or indoor opened (IO) conditions and provided biomass yields of approximately 8 to 27 g dry cell weight (DCW) floor m -2 d -1 . Alkanes of heptadecane (C 17 H 36 ) or pentadecane (C 15 H 32 ) as liquid biofuels were also recovered from the lower liquid-phase, in which cyanobacteria were dropped from the upper solid-phase and continuously cultivated with a small amount of medium. After the main cultivation in DuPHA, the upper solid-phase of a cotton cloth on which cyanobacteria grew was dried and directly subjected to a combustion test. This resulted in the thermal power (kJ s -1 ) of the cloth with microalgae increasing approximately 20 to 50% higher than that of the cloth only, suggesting a possibility of using the solid phase with microalgae as solid biofuel. Copyright © 2018. Published by Elsevier B.V.

Investigation of phase diagrams and physical stability of drug-polymer solid dispersions.

PubMed

Lu, Jiannan; Shah, Sejal; Jo, Seongbong; Majumdar, Soumyajit; Gryczke, Andreas; Kolter, Karl; Langley, Nigel; Repka, Michael A

2015-01-01

Solid dispersion technology has been widely explored to improve the solubility and bioavailability of poorly water-soluble compounds. One of the critical drawbacks associated with this technology is the lack of physical stability, i.e. the solid dispersion would undergo recrystallization or phase separation thus limiting a product's shelf life. In the current study, the melting point depression method was utilized to construct a complete phase diagram for felodipine (FEL)-Soluplus® (SOL) and ketoconazole (KTZ)-Soluplus® (SOL) binary systems, respectively, based on the Flory-Huggins theory. The miscibility or solubility of the two compounds in SOL was also determined. The Flory-Huggins interaction parameter χ values of both systems were calculated as positive at room temperature (25 °C), indicating either compound was miscible with SOL. In addition, the glass transition temperatures of both solid dispersion systems were theoretically predicted using three empirical equations and compared with the practical values. Furthermore, the FEL-SOL solid dispersions were subjected to accelerated stability studies for up to 3 months.

Shape and Symmetry Determine Two-Dimensional Melting Transitions of Hard Regular Polygons

NASA Astrophysics Data System (ADS)

Anderson, Joshua A.; Antonaglia, James; Millan, Jaime A.; Engel, Michael; Glotzer, Sharon C.

2017-04-01

The melting transition of two-dimensional systems is a fundamental problem in condensed matter and statistical physics that has advanced significantly through the application of computational resources and algorithms. Two-dimensional systems present the opportunity for novel phases and phase transition scenarios not observed in 3D systems, but these phases depend sensitively on the system and, thus, predicting how any given 2D system will behave remains a challenge. Here, we report a comprehensive simulation study of the phase behavior near the melting transition of all hard regular polygons with 3 ≤n ≤14 vertices using massively parallel Monte Carlo simulations of up to 1 ×106 particles. By investigating this family of shapes, we show that the melting transition depends upon both particle shape and symmetry considerations, which together can predict which of three different melting scenarios will occur for a given n . We show that systems of polygons with as few as seven edges behave like hard disks; they melt continuously from a solid to a hexatic fluid and then undergo a first-order transition from the hexatic phase to the isotropic fluid phase. We show that this behavior, which holds for all 7 ≤n ≤14 , arises from weak entropic forces among the particles. Strong directional entropic forces align polygons with fewer than seven edges and impose local order in the fluid. These forces can enhance or suppress the discontinuous character of the transition depending on whether the local order in the fluid is compatible with the local order in the solid. As a result, systems of triangles, squares, and hexagons exhibit a Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) predicted continuous transition between isotropic fluid and triatic, tetratic, and hexatic phases, respectively, and a continuous transition from the appropriate x -atic to the solid. In particular, we find that systems of hexagons display continuous two-step KTHNY melting. In contrast, due to symmetry incompatibility between the ordered fluid and solid, systems of pentagons and plane-filling fourfold pentilles display a one-step first-order melting of the solid to the isotropic fluid with no intermediate phase.

High speed real-time wavefront processing system for a solid-state laser system

NASA Astrophysics Data System (ADS)

Liu, Yuan; Yang, Ping; Chen, Shanqiu; Ma, Lifang; Xu, Bing

2008-03-01

A high speed real-time wavefront processing system for a solid-state laser beam cleanup system has been built. This system consists of a core2 Industrial PC (IPC) using Linux and real-time Linux (RT-Linux) operation system (OS), a PCI image grabber, a D/A card. More often than not, the phase aberrations of the output beam from solid-state lasers vary fast with intracavity thermal effects and environmental influence. To compensate the phase aberrations of solid-state lasers successfully, a high speed real-time wavefront processing system is presented. Compared to former systems, this system can improve the speed efficiently. In the new system, the acquisition of image data, the output of control voltage data and the implementation of reconstructor control algorithm are treated as real-time tasks in kernel-space, the display of wavefront information and man-machine conversation are treated as non real-time tasks in user-space. The parallel processing of real-time tasks in Symmetric Multi Processors (SMP) mode is the main strategy of improving the speed. In this paper, the performance and efficiency of this wavefront processing system are analyzed. The opened-loop experimental results show that the sampling frequency of this system is up to 3300Hz, and this system can well deal with phase aberrations from solid-state lasers.

A microstructure-based model for shape distortion during liquid phase sintering

NASA Astrophysics Data System (ADS)

Upadhyaya, Anish

Tight dimensional control is a major concern in consolidation of alloys via liquid phase sintering. This research demonstrates the role of microstructure in controlling the bulk dimensional changes that occur during liquid phase sintering. The dimensional changes were measured using a coordinate measuring machine and also on a real-time basis using in situ video imaging. To quantify compact distortion, a distortion parameter is formulated which takes into consideration the compact distortion in radial as well as axial directions. The microstructural attributes considered in this study are as follows: solid content, dihedral angle, grain size, grain contiguity and connectivity, and solid-solubility. Sintering experiments were conducted with the W-Ni-Cu, W-Ni-Fe, Mo-Ni-Cu, and Fe-Cu systems. The alloy systems and the compositions were selected to give a range of microstructures during liquid phase sintering. The results show that distortion correlates with the measured microstructural attributes. Systems containing a high solid content, high grain coordination number and contiguity, and large dihedral angle have more structural rigidity. The results show that a minimum two-dimensional grain coordination number of 3.0 is necessary for shape preservation. Based on the experimental observations, a model is derived that relates the critical solid content required for maintaining structural rigidity to the dihedral angle. The critical solid content decreases with an increasing dihedral angle. Consequently, W-Cu alloys, which have a dihedral angle of about 95sp°, can be consolidated without gross distortion with as little as 20 vol.% solid. To comprehensively understand the gravitational effects in the evolution of both the microstructure and the macrostructure during liquid phase sintering, W-Ni-Fe alloys with W content varying from 78 to 93 wt.% were sintered in microgravity. Compositions that slump during ground-based sintering also distort when sintered under microgravity. In ground-based sintering, low solid content alloys distort with a typical elephant-foot profile, while in microgravity, the compacts tend to spheroidize. This study shows that microstructural segregation occurs in both ground-based as well as microgravity sintering. In ground-based experiments, because of the density difference between the solid and the liquid phase, the solid content increases from top to the bottom of the sample. In microgravity, the solid content increases from periphery to the center of the samples. A model is derived to show that grain agglomeration and segregation are energetically favored events and will therefore be inherent to the system, even in the absence of gravity. Real time distortion measurement in alloys having appreciable solid-solubility in the liquid phase, such as W-Ni-Fe and Fe-Cu, show that the bulk of distortion occur within the first 5 min of melt formation. Distortion in such systems can be minimized by presaturating the matrix with the solid phase.

Recent Application of Solid Phase Based Techniques for Extraction and Preconcentration of Cyanotoxins in Environmental Matrices.

PubMed

Mashile, Geaneth Pertunia; Nomngongo, Philiswa N

2017-03-04

Cyanotoxins are toxic and are found in eutrophic, municipal, and residential water supplies. For this reason, their occurrence in drinking water systems has become a global concern. Therefore, monitoring, control, risk assessment, and prevention of these contaminants in the environmental bodies are important subjects associated with public health. Thus, rapid, sensitive, selective, simple, and accurate analytical methods for the identification and determination of cyanotoxins are required. In this paper, the sampling methodologies and applications of solid phase-based sample preparation methods for the determination of cyanotoxins in environmental matrices are reviewed. The sample preparation techniques mainly include solid phase micro-extraction (SPME), solid phase extraction (SPE), and solid phase adsorption toxin tracking technology (SPATT). In addition, advantages and disadvantages and future prospects of these methods have been discussed.

Mapping coexistence lines via free-energy extrapolation: application to order-disorder phase transitions of hard-core mixtures.

PubMed

Escobedo, Fernando A

2014-03-07

In this work, a variant of the Gibbs-Duhem integration (GDI) method is proposed to trace phase coexistence lines that combines some of the advantages of the original GDI methods such as robustness in handling large system sizes, with the ability of histogram-based methods (but without using histograms) to estimate free-energies and hence avoid the need of on-the-fly corrector schemes. This is done by fitting to an appropriate polynomial function not the coexistence curve itself (as in GDI schemes) but the underlying free-energy function of each phase. The availability of a free-energy model allows the post-processing of the simulated data to obtain improved estimates of the coexistence line. The proposed method is used to elucidate the phase behavior for two non-trivial hard-core mixtures: a binary blend of spheres and cubes and a system of size-polydisperse cubes. The relative size of the spheres and cubes in the first mixture is chosen such that the resulting eutectic pressure-composition phase diagram is nearly symmetric in that the maximum solubility of cubes in the sphere-rich solid (∼20%) is comparable to the maximum solubility of spheres in the cube-rich solid. In the polydisperse cube system, the solid-liquid coexistence line is mapped out for an imposed Gaussian activity distribution, which produces near-Gaussian particle-size distributions in each phase. A terminal polydispersity of 11.3% is found, beyond which the cubic solid phase would not be stable, and near which significant size fractionation between the solid and isotropic phases is predicted.

Predicting phase equilibria in one-component systems

NASA Astrophysics Data System (ADS)

Korchuganova, M. R.; Esina, Z. N.

2015-07-01

It is shown that Simon equation coefficients for n-alkanes and n-alcohols can be modeled using critical and triple point parameters. Predictions of the phase liquid-vapor, solid-vapor, and liquid-solid equilibria in one-component systems are based on the Clausius-Clapeyron relation, Van der Waals and Simon equations, and the principle of thermodynamic similarity.

A quantitative study of factors influencing lamellar eutectic morphology during solidification

NASA Technical Reports Server (NTRS)

Kaukler, W. F. S.

1981-01-01

The factors that influence the shape of the solid-liquid interface of a lamellar binary eutectic alloy are evaluated. Alloys of carbon tetrabromide and hexachloroethane which serve as a transparent analogue of lamellar metallic eutectics are used. The observed interface shapes are analyzed by computer-aided methods. The solid-liquid interfacial free energies of each of the individual phases comprising the eutectic system are measured as a function of composition using a 'grain boundary groove' technique. The solid-liquid interfacial free energy of the two phases are evaluated directly from the eutectic interface. The phase diagram for the system, the heat of fusion as a function of composition, and the density as a function of composition are measured. The shape of the eutectic interface is controlled mainly by the solid-liquid and solid-solid interfacial free energy relationships at the interface and by the temperature gradient present, rather than by interlamellar diffusion in the liquid at the interface, over the range of growth rates studied.

Phase equilibria and crystal structure of the complex oxides in the Sr Fe Co O system

NASA Astrophysics Data System (ADS)

Aksenova, T. V.; Gavrilova, L. Ya.; Cherepanov, V. A.

2008-06-01

Phase relations in the Sr-Fe-Co-O system have been investigated at 1100 °C in air by X-ray powder diffraction on quenched samples. Solid solutions of the form SrFe 1-xCo xO 3-δ (0⩽ x⩽0.7), Sr 3Fe 2-yCo yO 7-δ (0⩽ y⩽0.4) and Sr 4Fe 6-zCo zO 13±δ (0⩽ z⩽1.6) were prepared by solid-state reaction and by the sol-gel method. The structural parameters of single-phase samples were refined by the Rietveld profile method. The variation of the lattice parameters with composition has been determined for each solid solution and a cross-section of the phase diagram at 1100 °C in air for the entire Sr-Fe-Co-O system has been constructed.

Accelerated exploration of multi-principal element alloys with solid solution phases

PubMed Central

Senkov, O.N.; Miller, J.D.; Miracle, D.B.; Woodward, C.

2015-01-01

Recent multi-principal element, high entropy alloy (HEA) development strategies vastly expand the number of candidate alloy systems, but also pose a new challenge—how to rapidly screen thousands of candidate alloy systems for targeted properties. Here we develop a new approach to rapidly assess structural metals by combining calculated phase diagrams with simple rules based on the phases present, their transformation temperatures and useful microstructures. We evaluate over 130,000 alloy systems, identifying promising compositions for more time-intensive experimental studies. We find the surprising result that solid solution alloys become less likely as the number of alloy elements increases. This contradicts the major premise of HEAs—that increased configurational entropy increases the stability of disordered solid solution phases. As the number of elements increases, the configurational entropy rises slowly while the probability of at least one pair of elements favouring formation of intermetallic compounds increases more rapidly, explaining this apparent contradiction. PMID:25739749

Phase Relations in Ternary Systems in the Subsolidus Region: Methods to Formulate Solid Solution Equations and to Find Particular Compositions

ERIC Educational Resources Information Center

Alvarez-Montan~o, Victor E.; Farías, Mario H.; Brown, Francisco; Mun~oz-Palma, Iliana C.; Cubillas, Fernando; Castillon-Barraza, Felipe F.

2017-01-01

A good understanding of ternary phase diagrams is required to advance and/or to reproduce experimental research in solid-state and materials chemistry. The aim of this paper is to describe the solutions to problems that appear when studying or determining ternary phase diagrams. A brief description of the principal features shown in phase diagrams…

CRYOCHEM, Thermodynamic Model for Cryogenic Chemical Systems: Solid-Vapor and Solid-Liquid-Vapor Phase Equilibria Toward Applications on Titan and Pluto

NASA Astrophysics Data System (ADS)

Tan, S. P.; Kargel, J. S.; Adidharma, H.; Marion, G. M.

2014-12-01

Until in-situ measurements can be made regularly on extraterrestrial bodies, thermodynamic models are the only tools to investigate the properties and behavior of chemical systems on those bodies. The resulting findings are often critical in describing physicochemical processes in the atmosphere, surface, and subsurface in planetary geochemistry and climate studies. The extremely cold conditions on Triton, Pluto and other Kuiper Belt Objects, and Titan introduce huge non-ideality that prevents conventional models from performing adequately. At such conditions, atmospheres as a whole—not components individually—are subject to phase equilibria with their equilibrium solid phases or liquid phases or both. A molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, the development of which is still in progress, was shown to reproduce the vertical composition profile of Titan's atmospheric methane measured by the Huygens probe (Tan et al., Icarus 2013, 222, 53). Recently, the model was also used to describe Titan's global circulation where the calculated composition of liquid in Ligeia Mare is consistent with the bathymetry and microwave absorption analysis of T91 Cassini fly-by data (Tan et al., 2014, submitted). Its capability to deal with equilibria involving solid phases has also been demonstrated (Tan et al., Fluid Phase Equilib. 2013, 360, 320). With all those previous works done, our attention is now shifting to the lower temperatures in Titan's tropopause and on Pluto's surface, where much technical development remains for CRYOCHEM to assure adequate performance at low temperatures. In these conditions, solid-vapor equilibrium (SVE) is the dominant phase behavior that determines the composition of the atmosphere and the existing ices. Another potential application is for the subsurface phase equilibrium, which also involves liquid, thus three-phase equilibrium: solid-liquid-vapor (SLV). This presentation will discuss the current state of CRYOCHEM in representing the SVE and SLV of chemical systems at temperatures and pressures relevant to Titan's tropopause and Pluto and the upper crusts of these objects.

Non-Abelian Geometric Phases Carried by the Quantum Noise Matrix

NASA Astrophysics Data System (ADS)

Bharath, H. M.; Boguslawski, Matthew; Barrios, Maryrose; Chapman, Michael

2017-04-01

Topological phases of matter are characterized by topological order parameters that are built using Berry's geometric phase. Berry's phase is the geometric information stored in the overall phase of a quantum state. We show that geometric information is also stored in the second and higher order spin moments of a quantum spin system, captured by a non-abelian geometric phase. The quantum state of a spin-S system is uniquely characterized by its spin moments up to order 2S. The first-order spin moment is the spin vector, and the second-order spin moment represents the spin fluctuation tensor, i.e., the quantum noise matrix. When the spin vector is transported along a loop in the Bloch ball, we show that the quantum noise matrix picks up a geometric phase. Considering spin-1 systems, we formulate this geometric phase as an SO(3) operator. Geometric phases are usually interpreted in terms of the solid angle subtended by the loop at the center. However, solid angles are not well defined for loops that pass through the center. Here, we introduce a generalized solid angle which is well defined for all loops inside the Bloch ball, in terms of which, we interpret the SO(3) geometric phase. This geometric phase can be used to characterize topological spin textures in cold atomic clouds.

Freezing Transition Studies Through Constrained Cell Model Simulation

NASA Astrophysics Data System (ADS)

Nayhouse, Michael; Kwon, Joseph Sang-Il; Heng, Vincent R.; Amlani, Ankur M.; Orkoulas, G.

2014-10-01

In the present work, a simulation method based on cell models is used to deduce the fluid-solid transition of a system of particles that interact via a pair potential, , which is of the form with . The simulations are implemented under constant-pressure conditions on a generalized version of the constrained cell model. The constrained cell model is constructed by dividing the volume into Wigner-Seitz cells and confining each particle in a single cell. This model is a special case of a more general cell model which is formed by introducing an additional field variable that controls the number of particles per cell and, thus, the relative stability of the solid against the fluid phase. High field values force configurations with one particle per cell and thus favor the solid phase. Fluid-solid coexistence on the isotherm that corresponds to a reduced temperature of 2 is determined from constant-pressure simulations of the generalized cell model using tempering and histogram reweighting techniques. The entire fluid-solid phase boundary is determined through a thermodynamic integration technique based on histogram reweighting, using the previous coexistence point as a reference point. The vapor-liquid phase diagram is obtained from constant-pressure simulations of the unconstrained system using tempering and histogram reweighting. The phase diagram of the system is found to contain a stable critical point and a triple point. The phase diagram of the corresponding constrained cell model is also found to contain both a stable critical point and a triple point.

Wave transmission approach based on modal analysis for embedded mechanical systems

NASA Astrophysics Data System (ADS)

Cretu, Nicolae; Nita, Gelu; Ioan Pop, Mihail

2013-09-01

An experimental method for determining the phase velocity in small solid samples is proposed. The method is based on measuring the resonant frequencies of a binary or ternary solid elastic system comprising the small sample of interest and a gauge material of manageable size. The wave transmission matrix of the combined system is derived and the theoretical values of its eigenvalues are used to determine the expected eigenfrequencies that, equated with the measured values, allow for the numerical estimation of the phase velocities in both materials. The known phase velocity of the gauge material is then used to asses the accuracy of the method. Using computer simulation and the experimental values for phase velocities, the theoretical values for the eigenfrequencies of the eigenmodes of the embedded elastic system are obtained, to validate the method. We conclude that the proposed experimental method may be reliably used to determine the elastic properties of small solid samples whose geometries do not allow a direct measurement of their resonant frequencies.

Experimental Liquidus Studies of the Pb-Cu-Si-O System in Equilibrium with Metallic Pb-Cu Alloys

NASA Astrophysics Data System (ADS)

Shevchenko, M.; Nicol, S.; Hayes, P. C.; Jak, E.

2018-03-01

Phase equilibria of the Pb-Cu-Si-O system have been investigated in the temperature range from 1073 K to 1673 K (800 °C to 1400 °C) for oxide liquid (slag) in equilibrium with solid Cu metal and/or liquid Pb-Cu alloy, and solid oxide phases: (a) quartz or tridymite (SiO2) and (b) cuprite (Cu2O). High-temperature equilibration on silica or copper substrates was performed, followed by quenching, and direct measurement of Pb, Cu, and Si concentrations in the liquid and solid phases using the electron probe X-ray microanalysis has been employed to accurately characterize the system in equilibrium with Cu or Pb-Cu metal. All results are projected onto the PbO-"CuO0.5"-SiO2 plane for presentation purposes. The present study is the first-ever systematic investigation of this system to describe the slag liquidus temperatures in the silica and cuprite primary phase fields.

Separation of phenolic acids from sugarcane rind by online solid-phase extraction with high-speed counter-current chromatography.

PubMed

Geng, Ping; Fang, Yingtong; Xie, Ronglong; Hu, Weilun; Xi, Xingjun; Chu, Qiao; Dong, Genlai; Shaheen, Nusrat; Wei, Yun

2017-02-01

Sugarcane rind contains some functional phenolic acids. The separation of these compounds from sugarcane rind is able to realize the integrated utilization of the crop and reduce environment pollution. In this paper, a novel protocol based on interfacing online solid-phase extraction with high-speed counter-current chromatography (HSCCC) was established, aiming at improving and simplifying the process of phenolic acids separation from sugarcane rind. The conditions of online solid-phase extraction with HSCCC involving solvent system, flow rate of mobile phase as well as saturated extent of absorption of solid-phase extraction were optimized to improve extraction efficiency and reduce separation time. The separation of phenolic acids was performed with a two-phase solvent system composed of butanol/acetic acid/water at a volume ratio of 4:1:5, and the developed online solid-phase extraction with HSCCC method was validated and successfully applied for sugarcane rind, and three phenolic acids including 6.73 mg of gallic acid, 10.85 mg of p-coumaric acid, and 2.78 mg of ferulic acid with purities of 60.2, 95.4, and 84%, respectively, were obtained from 150 mg sugarcane rind crude extracts. In addition, the three different elution methods of phenolic acids purification including HSCCC, elution-extrusion counter-current chromatography and back-extrusion counter-current chromatography were compared. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A review of solid-fluid selection options for optical-based measurements in single-phase liquid, two-phase liquid-liquid and multiphase solid-liquid flows

NASA Astrophysics Data System (ADS)

Wright, Stuart F.; Zadrazil, Ivan; Markides, Christos N.

2017-09-01

Experimental techniques based on optical measurement principles have experienced significant growth in recent decades. They are able to provide detailed information with high-spatiotemporal resolution on important scalar (e.g., temperature, concentration, and phase) and vector (e.g., velocity) fields in single-phase or multiphase flows, as well as interfacial characteristics in the latter, which has been instrumental to step-changes in our fundamental understanding of these flows, and the development and validation of advanced models with ever-improving predictive accuracy and reliability. Relevant techniques rely upon well-established optical methods such as direct photography, laser-induced fluorescence, laser Doppler velocimetry/phase Doppler anemometry, particle image/tracking velocimetry, and variants thereof. The accuracy of the resulting data depends on numerous factors including, importantly, the refractive indices of the solids and liquids used. The best results are obtained when the observational materials have closely matched refractive indices, including test-section walls, liquid phases, and any suspended particles. This paper reviews solid-liquid and solid-liquid-liquid refractive-index-matched systems employed in different fields, e.g., multiphase flows, turbomachinery, bio-fluid flows, with an emphasis on liquid-liquid systems. The refractive indices of various aqueous and organic phases found in the literature span the range 1.330-1.620 and 1.251-1.637, respectively, allowing the identification of appropriate combinations to match selected transparent or translucent plastics/polymers, glasses, or custom materials in single-phase liquid or multiphase liquid-liquid flow systems. In addition, the refractive indices of fluids can be further tuned with the use of additives, which also allows for the matching of important flow similarity parameters such as density and viscosity.

Microwave spectroscopic observation of multiple phase transitions in the bilayer electron solid in wide quantum wells

NASA Astrophysics Data System (ADS)

Hatke, Anthony; Engel, Lloyd; Liu, Yang; Shayegan, Mansour; Pfeiffer, Loren; West, Ken; Baldwin, Kirk

2015-03-01

The termination of the low Landau filling factor (ν) fractional quantum Hall series for a single layer two dimensional system results in the formation of a pinned Wigner solid for ν < 1 / 5. In a wide quantum well the system can support a bilayer state in which interlayer and intralayer interactions become comparable, which is measured in traditional transport as an insulating state for ν < 1 / 2. We perform microwave spectroscopic studies of this bilayer state and observe that this insulator exhibits a resonance, a signature of a solid phase. Additionally, we find that as we increase the density of the well at fixed ν this bilayer solid exhibits multiple sharp reductions in the resonance amplitude vs ν. This behavior is characteristic of multiple phase transitions, which remain hidden from dc transport measurements.

Kerr-AdS analogue of triple point and solid/liquid/gas phase transition

NASA Astrophysics Data System (ADS)

Altamirano, Natacha; Kubizňák, David; Mann, Robert B.; Sherkatghanad, Zeinab

2014-02-01

We study the thermodynamic behavior of multi-spinning d = 6 Kerr-anti de Sitter black holes in the canonical ensemble of fixed angular momenta J1 and J2. We find, dependent on the ratio q = J2/J1, qualitatively different interesting phenomena known from the ‘every day thermodynamics’ of simple substances. For q = 0 the system exhibits recently observed reentrant large/small/large black hole phase transitions, but for 0 < q ≪ 1 we find an analogue of a ‘solid/liquid’ phase transition. Furthermore, for q ∈ (0.00905, 0.0985) the system displays the presence of a large/intermediate/small black hole phase transition with two critical and one triple (or tricritical) points. This behavior is reminiscent of the solid/liquid/gas phase transition except that the coexistence line of small and intermediate black holes does not continue for an arbitrary value of pressure (similar to the solid/liquid coexistence line) but rather terminates at one of the critical points. Finally, for q > 0.0985 we observe the ‘standard liquid/gas behavior’ of the Van der Waals fluid.

AUTOMATED ANALYSIS OF AQUEOUS SAMPLES CONTAINING PESTICIDES, ACIDIC/BASIC/NEUTRAL SEMIVOLATILES AND VOLATILE ORGANIC COMPOUNDS BY SOLID PHASE EXTRACTION COUPLED IN-LINE TO LARGE VOLUME INJECTION GC/MS

EPA Science Inventory

Data is presented on the development of a new automated system combining solid phase extraction (SPE) with GC/MS spectrometry for the single-run analysis of water samples containing a broad range of organic compounds. The system uses commercially available automated in-line 10-m...

Novel Anaerobic Wastewater Treatment System for Energy Generation at Forward Operating Bases

DTIC Science & Technology

2016-08-01

AnMBR) technology with clinoptilolite ion exchange and GreenBox™ ammonia electrolysis. The system generates both methane and hydrogen fuels...experimental setup. ................................................ 21 Figure 10. Methane phase semi batch experimental setup, a total of three reactors were...set up for PS + solid, Bioc and ADS methane phase reactors. .................... 21 Figure 11. Dried PS solid for the control, Bioc blend for the

Study of phase relationships in the Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system. Phase diagram and thermal characteristics of phases

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

Matraszek, Aleksandra, E-mail: aleksandra.matraszek@ue.wroc.pl

2013-07-15

A diagram representing phase relationships in the Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} phosphate system has been developed on the basis of results obtained by thermal analysis (DTA/DSC/TGA) and X-ray diffraction (XRD) methods. One intermediate compound with the formula Sr{sub 3}Ce(PO{sub 4}){sub 3} occurs in the Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system at temperatures exceeding 1045 °C. The compound has a eulytite structure with the following structural parameters: a=b=c=10.1655(8) Å, α=β=γ=90.00°, V=1050.46(6) Å{sup 3}. It's melting point exceeds 1950 °C. A limited solid solution exists in the system, which possesses the structure of a low-temperature form of Sr{sub 3}(PO{sub 4}){sub 2}.more » At 1000 °C the maximal concentration of CePO{sub 4} in the solid solution is below 20 mol%. The solid solution phase field narrows with increased temperature. There is a eutectic point in the (Sr{sub 3}(PO{sub 4}){sub 2}+Sr{sub 3}Ce(PO{sub 4}){sub 3}) phase field at 1765 °C and 15 mol% of CePO{sub 4}. The melting temperature of Sr{sub 3}(PO{sub 4}){sub 2} is 1882±15 °C. - Graphical abstract: The phase diagram of Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system showing the stability ranges of limited solid solution and Sr{sub 3}Ce(PO{sub 4}){sub 3} phases. - Highlights: • Sr{sub 3}(PO{sub 4}){sub 2} melts at 1882 °C. • Phase diagram of Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system has been proposed. • Limited solid solution of CePO{sub 4} in Sr{sub 3}(PO{sub 4}){sub 2} forms in the system. • The Sr{sub 3}Ce(PO{sub 4}){sub 2} phosphate is stable at temperatures above 1045 °C.« less

Magnetic islands modelled by a phase-field-crystal approach

NASA Astrophysics Data System (ADS)

Faghihi, Niloufar; Mkhonta, Simiso; Elder, Ken R.; Grant, Martin

2018-03-01

Using a minimal model based on the phase-field-crystal formalism, we study the coupling between the density and magnetization in ferromagnetic solids. Analytical calculations for the square phase in two dimensions are presented and the small deformation properties of the system are examined. Furthermore, numerical simulations are conducted to study the influence of an external magnetic field on various phase transitions, the anisotropic properties of the free energy functional, and the scaling behaviour of the growth of the magnetic domains in a crystalline solid. It is shown that the energy of the system can depend on the direction of the magnetic moments, with respect to the crystalline direction. Furthermore, the growth of the magnetic domains in a crystalline solid is studied and is shown that the growth of domains is in agreement with expected behaviour.

MBSSAS: A code for the computation of margules parameters and equilibrium relations in binary solid-solution aqueous-solution systems

USGS Publications Warehouse

Glynn, P.D.

1991-01-01

The computer code MBSSAS uses two-parameter Margules-type excess-free-energy of mixing equations to calculate thermodynamic equilibrium, pure-phase saturation, and stoichiometric saturation states in binary solid-solution aqueous-solution (SSAS) systems. Lippmann phase diagrams, Roozeboom diagrams, and distribution-coefficient diagrams can be constructed from the output data files, and also can be displayed by MBSSAS (on IBM-PC compatible computers). MBSSAS also will calculate accessory information, such as the location of miscibility gaps, spinodal gaps, critical-mixing points, alyotropic extrema, Henry's law solid-phase activity coefficients, and limiting distribution coefficients. Alternatively, MBSSAS can use such information (instead of the Margules, Guggenheim, or Thompson and Waldbaum excess-free-energy parameters) to calculate the appropriate excess-free-energy of mixing equation for any given SSAS system. ?? 1991.

Efficient removal of recalcitrant deep-ocean dissolved organic matter during hydrothermal circulation

NASA Astrophysics Data System (ADS)

Hawkes, Jeffrey A.; Rossel, Pamela E.; Stubbins, Aron; Butterfield, David; Connelly, Douglas P.; Achterberg, Eric P.; Koschinsky, Andrea; Chavagnac, Valérie; Hansen, Christian T.; Bach, Wolfgang; Dittmar, Thorsten

2015-11-01

Oceanic dissolved organic carbon (DOC) is an important carbon pool, similar in magnitude to atmospheric CO2, but the fate of its oldest forms is not well understood. Hot hydrothermal circulation may facilitate the degradation of otherwise un-reactive dissolved organic matter, playing an important role in the long-term global carbon cycle. The oldest, most recalcitrant forms of DOC, which make up most of oceanic DOC, can be recovered by solid-phase extraction. Here we present measurements of solid-phase extractable DOC from samples collected between 2009 and 2013 at seven vent sites in the Atlantic, Pacific and Southern oceans, along with magnesium concentrations, a conservative tracer of water circulation through hydrothermal systems. We find that magnesium and solid-phase extractable DOC concentrations are correlated, suggesting that solid-phase extractable DOC is almost entirely lost from solution through mineralization or deposition during circulation through hydrothermal vents with fluid temperatures of 212-401 °C. In laboratory experiments, where we heated samples to 380 °C for four days, we found a similar removal efficiency. We conclude that thermal degradation alone can account for the loss of solid-phase extractable DOC in natural hydrothermal systems, and that its maximum lifetime is constrained by the timescale of hydrothermal cycling, at about 40 million years.

Evaluation of the solubility constants of the hydrated solid phases in the H2O-Al2O3-SO3 ternary system

NASA Astrophysics Data System (ADS)

Teyssier, A.; Lagneau, V.; Schmitt, J. M.; Counioux, J. J.; Goutaudier, C.

2017-04-01

During the acid processing of aluminosilicate ores, the precipitation of a solid phase principally consisting of hydrated aluminium hydroxysulfates may be observed. The experimental study of the H2O-Al2O3-SO3 ternary system at 25 ∘C and 101 kPa enabled to describe the solid-liquid equilibra and to identify the nature, the composition and the solubility of the solid phases which may form during the acid leaching. To predict the appearance of these aluminium hydroxysulfates in more complex systems, their solubility constants were calculated by modelling the experimental solubility results, using a geochemical reaction modelling software, CHESS. A model for non-ideality correction, based on the B-dot equation, was used as it was suitable for the considered ion concentration range. The solubility constants of three out of four solid phases were calculated: 104.08 for jurbanite (Al(SO4)(OH).5H2O), 1028.09 for the solid T (Al8(SO4)5(OH)14.34H2O) and 1027.28 for the solid V (Al10(SO4)3(OH)24.20H2O). However the activity correction model was not suitable to determine the solubility constant of alunogen (Al2(SO4)3.15.8H2O), as the ion concentrations of the mixtures were too high and beyond the allowable limits of the model. Another ionic activity correction model, based on the Pitzer equation for example, must be applied to calculate the solubility constant of alunogen.

LiOH - H2O2 - H2O trinary system study for the selection of optimal conditions of lithium peroxide synthesis

NASA Astrophysics Data System (ADS)

Nefedov, R. A.; Ferapontov, Yu A.; Kozlova, N. P.

2016-01-01

Using solubility method the decay kinetics of peroxide products contained in liquid phase of LiOH - H2O2 - H2O trinary system with 2 to 6% by wt hydrogen peroxide content in liquid phase in 21 to 33 °C temperature range has been studied. Conducted studies have allowed to determine temperature and concentration limits of solid phase existence of Li2O2·H2O content, distinctness of which has been confirmed using chemical and qualitative X- ray phase analysis. Stabilizing effect of solid phase of Li2O2·H2O content on hydrogen peroxide decay contained in liquid phase of LiOH - H2O2 - H2O trinary system under conditions of experiments conducted has been shown.

Solidification studies of monotectic systems

NASA Technical Reports Server (NTRS)

Chang, K.

1982-01-01

Described is an attempt to determine critical wetting temperatures in monotectic systems and to investigate the wetting phase on container walls and the phase preferential wetting of a monotectic solid.

Improved modeling of two-dimensional transitions in dense phases on crystalline surfaces. Krypton–graphite system

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

Ustinov, E. A., E-mail: eustinov@mail.wplus.net

This paper presents a refined technique to describe two-dimensional phase transitions in dense fluids adsorbed on a crystalline surface. Prediction of parameters of 2D liquid–solid equilibrium is known to be an extremely challenging problem, which is mainly due to a small difference in thermodynamic functions of coexisting phases and lack of accuracy of numerical experiments in case of their high density. This is a serious limitation of various attempts to circumvent this problem. To improve this situation, a new methodology based on the kinetic Monte Carlo method was applied. The methodology involves analysis of equilibrium gas–liquid and gas–solid systems undergoingmore » an external potential, which allows gradual shifting parameters of the phase coexistence. The interrelation of the chemical potential and tangential pressure for each system is then treated with the Gibbs–Duhem equation to obtain the point of intersection corresponding to the liquid/solid–solid equilibrium coexistence. The methodology is demonstrated on the krypton–graphite system below and above the 2D critical temperature. Using experimental data on the liquid–solid and the commensurate–incommensurate transitions in the krypton monolayer derived from adsorption isotherms, the Kr–graphite Lennard–Jones parameters have been corrected resulting in a higher periodic potential modulation.« less

COMPARISON OF TWO DIFFERENT SOLID PHASE EXTRACTION/LARGE VOLUME INJECTION PROCEDURES FOR METHOD 8270

EPA Science Inventory

Two solid phase (SPE) and one traditional continuous liquid-liquid extraction method are compared for analysis of Method 8270 SVOCs. Productivity parameters include data quality, sample volume, analysis time and solvent waste.

One SPE system, unique in the U.S., uses aut...

Study of the solid-state amorphization of (GaSb){sub 1-x}Ge{sub x} semiconductors by real-time neutron diffraction and electron microscopy

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

Fedotov, V. K., E-mail: fedotov@issp.ac.ru; Ponyatovsky, E. G.

2011-12-15

The spontaneous amorphization of high-pressure quenched phases of the GaSb-Ge system has been studied by neutron diffraction while slowly heating the phases at atmospheric pressure. The sequence of changes in the structural parameters of the initial crystalline phase and the final amorphous phase is established. The behavior of the phases and the correlation in the structural features of the phase transitions and anomalous thermal effects exhibit signs of the inhomogeneous model of solid-state amorphization.

Bioremediation of diesel fuel contaminated soil: effect of non ionic surfactants and selected bacteria addition.

PubMed

Collina, Elena; Lasagni, Marina; Pitea, Demetrio; Franzetti, Andrea; Di Gennaro, Patrizia; Bestetti, Giuseppina

2007-09-01

Aim of this work was to evaluate influence of two commercial surfactants and inoculum of selected bacteria on biodegradation of diesel fuel in different systems. Among alkyl polyethossilates (Brij family) and sorbitan derivates (Tween family) a first selection of surfactants was performed by estimation of Koc and Dafnia magna EC50 with molecular descriptor and QSAR model. Further experiments were conducted to evaluate soil sorption, biodegradability and toxicity. In the second part of the research, the effect of Brij 56, Tween 80 and selected bacteria addition on biodegradation of diesel fuel was studied in liquid cultures and in slurry and solid phase systems. The latter experiments were performed with diesel contaminated soil in bench scale slurry phase bioreactor and solid phase columns. Tween 80 addition increased the biodegradation rate of hydrocarbons both in liquid and in slurry phase systems. Regarding the effect of inoculum, no enhancement of biodegradation rate was observed neither in surfactant added nor in experiments without addition. On the contrary, in solid phase experiments, inoculum addition resulted in enhanced biodegradation compared to surfactant addition.

Energy and Resource Saving of Steelmaking Process: Utilization of Innovative Multi-phase Flux During Dephosphorization Process

NASA Astrophysics Data System (ADS)

Matsuura, Hiroyuki; Hamano, Tasuku; Zhong, Ming; Gao, Xu; Yang, Xiao; Tsukihashi, Fumitaka

2014-09-01

An increase in the utilization efficiency of CaO, one of the major fluxing agents used in various steelmaking processes, is required to reduce the amount of discharged slag and energy consumption of the process. The authors have intensively focused on the development of innovative dephosphorization process by using so called "multi-phase flux" composed of solid and liquid phases. This article summarizes the research on the above topic done by the authors, in which the formation mechanisms of P2O5-containing phase during CaO or 2CaO·SiO2 dissolution into molten slag, the phase relationship between solid and liquid phases at equilibrium, and thermodynamic properties of P2O5-containing phase have been clarified. The reactions between solid CaO or 2CaO·SiO2 and molten CaO-FeO x -SiO2-P2O5 slag were observed by dipping solid specimen in the synthesized slag at 1573 K or 1673 K. The formation of the CaO-FeO layer and dual-phase layer of solid 2CaO·SiO2 and FeO x -rich liquid phase was observed around the interface from the solid CaO side toward the bulk slag phase side. Condensation of P2O5 into 2CaO·SiO2 phase as 2CaO·SiO2-3CaO·P2O5 solid solution was observed in both cases of CaO and 2CaO·SiO2 as solid specimens. Measurement of the phase relationship for the CaO-FeO x -SiO2-P2O5 system confirmed the condensation of P2O5 in solid phase at low oxygen partial pressure. The thermodynamics of 2CaO·SiO2-3CaO·P2O5 solid solution are to be clarified to quantitatively simulate the dephosphorization process, and the current results are also introduced. Based on the above results, the reduction of CaO consumption, the discharged slag curtailment, and energy-saving effects have been discussed.

Modeling the Capillary Pressure for the Migration of the Liquid Phase in Granular Solid-Liquid-Vapor Systems: Application to the Control of the Composition Profile in W-Cu FGM Materials

NASA Astrophysics Data System (ADS)

Missiaen, Jean-Michel; Raharijaona, Jean-Joël; Delannay, Francis

2016-11-01

A model is developed to compute the capillary pressure for the migration of the liquid phase out or into a uniform solid-liquid-vapor system. The capillary pressure is defined as the reduction of the overall interface energy per volume increment of the transferred fluid phase. The model takes into account the particle size of the solid particle aggregate, the packing configuration (coordination number, porosity), the volume fractions of the different phases, and the values of the interface energies in the system. The model is used for analyzing the stability of the composition profile during processing of W-Cu functionally graded materials combining a composition gradient with a particle size gradient. The migration pressure is computed with the model in two stages: (1) just after the melting of copper, i.e., when sintering and shape accommodation of the W particle aggregate can still be neglected and (2) at high temperature, when the system is close to full density with equilibrium particle shape. The model predicts well the different stages of liquid-phase migration observed experimentally.

Modelling Equilibrium and Fractional Crystallization in the System MgO-FeO-CaO-Al2O3-SiO2

NASA Technical Reports Server (NTRS)

Herbert, F.

1985-01-01

A mathematical modelling technique for use in petrogenesis calculations in the system MgO-FeO-CaO-Al2O3-SiO2 is reported. Semiempirical phase boundary and elemental distribution information was combined with mass balance to compute approximate equilibrium crystallization paths for arbitrary system compositions. The calculation is applicable to a range of system compositions and fractionation calculations are possible. The goal of the calculation is the computation of the composition and quantity of each phase present as a function of the degree of solidification. The degree of solidification is parameterized by the heat released by the solidifying phases. The mathematical requirement for the solution of this problem is: (1) An equation constraining the composition of the magma for each solid phase in equilibrium with the liquidus phase, and (2) an equation for each solid phase and each component giving the distribution of that element between that phase and the magma.

Survey of Portions of the Chromium-Cobalt-Nickel-Molybdenum Quaternary System at 1,200 Degrees C

NASA Technical Reports Server (NTRS)

Rideout, Sheldon Paul; Beck, Paul A

1953-01-01

A survey was made of portions of the chromium-cobalt-nickel-molybdenum quaternary system at 1,200 degrees c by means of microscopic and x-ray diffraction studies. Since the face-centered cubic (alpha) solid solutions form the matrix of almost all practically useful high-temperature alloys, the solid solubility limits of the quaternary alpha phase were determined up to 20 percent molybdenum. The component cobalt-nickel-molybdenum, chromium-cobalt-molybdenum, and chromium-nickel-molybdenum ternary systems were also studied. The survey of these systems was confined to the determination of the boundaries of the face-centered cubic (alpha) solid solutions and of the phases coexisting with alpha at 1,200 degrees c.

Deformability of adsorbents during adsorption and principles of the thermodynamics of solid-phase systems

NASA Astrophysics Data System (ADS)

Tovbin, Yu. K.

2017-09-01

A microscopic theory of adsorption, based on a discrete continuum lattice gas model for noninert (including deformable) adsorbents that change their lattice parameters during adsorption, is presented. Cases of the complete and partial equilibrium states of the adsorbent are considered. In the former, the adsorbent consists of coexisting solid and vapor phases of adsorbent components, and the adsorbate is a mobile component of the vapor phase with an arbitrary density (up to that of the liquid adsorbate phase). The adsorptive transitioning to the bound state changes the state of the near-surface region of the adsorbent. In the latter, there are no equilibrium components of the adsorbent between the solid and vapor phases. The adsorbent state is shown to be determined by its prehistory, rather than set by chemical potentials of vapor of its components. Relations between the microscopic theory and thermodynamic interpretations are discussed: (1) adsorption on an open surface, (2) two-dimensional stratification of the adsorbate mobile phase on an open homogeneous surface, (3) small microcrystals in vacuum and the gas phase, and (4) adsorption in porous systems.

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

Iwamoto, Y.; Shin, S.G.; Matsubara, H.

The grain growth behavior of ceramic materials under the existence of a liquid phase was investigated for Si{sub 3}N{sub 4}-Y{sub 2}O{sub 3}-SiO{sub 2}, TiC-Ni, and WC-Co systems. The kinetics of grain growth behavior of these systems closely fitted to the cubic relation of d{sup 3} - d{sub 0}{sup 3} = Kt. The growth rate of {beta}-Si{sub 3}N{sub 4} grain was approximately one order of magnitude larger in length direction than that in width direction. The growth rate slightly increased with increasing liquid phase content in both these directions of the {beta}-Si{sub 3}N{sub 4} grain. TiC-Ni and WC-Co cermets had amore » peak in growth rate at a certain liquid phase content. The rate constant values of these systems were much smaller by a factor of 10{sup 3}{approximately}10{sup 5} compared to the theoretical values expected from the diffusion-controlled growth model. The experimental growth rates tended to decrease with increasing contiguity of the solid phase. The grain growth behavior of these systems could be explained by the mechanism resulting from the existence of contiguous boundaries of solid phase, which suppressed the movement of solid/liquid interfaces during liquid phase sintering.« less

Phase relations in the system CuMoS

USGS Publications Warehouse

Dawei, H.; Chang, L.L.Y.; Knowles, C.R.

1990-01-01

Phase relations in the system CuMoS were studied in the temperature range 500-1000 ??C by using the conventional sealed, evacuated glass capsule technique. Reflected-light microscopy, X-ray powder diffraction and electron microprobe analysis were used for phase characterization. The chevrel-type phase, CuxMo3S4, is stable above 600??C, and forms equilibrium assemblages with the cubic Cu2S solid solution, copper, molybdenum, Mo2S3 and MoS2. Its solid solution ranges from Cu1.50-2.00Mo3S4 at 700??C to Cu1.22-2.00Mo3S4 at 1000 ??C. ?? 1990.

Lattice crossover and phase transitions in NdAlO{sub 3}-GdAlO{sub 3} system

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

Vasylechko, L., E-mail: crystal-lov@polynet.lviv.ua; Shmanko, H.; Ohon, N.

2013-02-15

Phase and structural behaviour in the (1-x)NdAlO{sub 3}-xGdAlO{sub 3} system in a whole concentration range has been studied by means of in situ high-resolution X-ray synchrotron powder diffraction technique and differential thermal analysis. Two kinds of solid solutions Nd{sub 1-x}Gd{sub x}AlO{sub 3} have been found at room temperature: one with rhombohedral (x<0.15) and one with orthorhombic (x{>=}0.20) symmetry. A morphotropic phase transition occurs at x Almost-Equal-To 0.15, where the co-existence of both phases was observed. Peculiarity of the orthorhombic solid solution is the lattice parameter crossover at the compositions with x=0.33, 0.49 and 0.62. First-order structural transition Pbnm{r_reversible}R3{sup Macron }cmore » has been detected both from in situ powder diffraction and thermal analysis data. Continuous phase transformation R3{sup Macron }c{r_reversible}Pm3{sup Macron }m above 2140 K has been predicted for Nd-rich sample Nd{sub 0.85}Gd{sub 0.15}AlO{sub 3} from the extrapolation of high-temperature behaviour of the lattice parameter ratio of the rhombohedral phase. Based on the experimental data, the phase diagram of the pseudo-binary system NdAlO{sub 3}-GdAlO{sub 3} has been constructed. - Graphical abstract: Concentration dependencies of normalized lattice parameters of Nd{sub 1-x}Gd{sub x}AlO{sub 3} perovskite solid solutions. Highlights: Black-Right-Pointing-Pointer Two kinds of solid solutions Nd{sub 1-x}Gd{sub x}AlO{sub 3} were found in the NdAlO{sub 3}-GdAlO{sub 3} system. Black-Right-Pointing-Pointer Morphotropic transition between both perovskite phases occurs at x Almost-Equal-To 0.15. Black-Right-Pointing-Pointer Lattice parameter crossover was found in orthorhombic solid solution. Black-Right-Pointing-Pointer Temperature driven first-order phase transition Pbnm{r_reversible}R3{sup Macron }c was found in Nd{sub 1-x}Gd{sub x}AlO{sub 3}. Black-Right-Pointing-Pointer Phase diagram of the pseudo-binary system NdAlO{sub 3}-GdAlO{sub 3} has been constructed.« less

Parallel Grand Canonical Monte Carlo (ParaGrandMC) Simulation Code

NASA Technical Reports Server (NTRS)

Yamakov, Vesselin I.

2016-01-01

This report provides an overview of the Parallel Grand Canonical Monte Carlo (ParaGrandMC) simulation code. This is a highly scalable parallel FORTRAN code for simulating the thermodynamic evolution of metal alloy systems at the atomic level, and predicting the thermodynamic state, phase diagram, chemical composition and mechanical properties. The code is designed to simulate multi-component alloy systems, predict solid-state phase transformations such as austenite-martensite transformations, precipitate formation, recrystallization, capillary effects at interfaces, surface absorption, etc., which can aid the design of novel metallic alloys. While the software is mainly tailored for modeling metal alloys, it can also be used for other types of solid-state systems, and to some degree for liquid or gaseous systems, including multiphase systems forming solid-liquid-gas interfaces.

Diffusion relaxation times of nonequilibrium isolated small bodies and their solid phase ensembles to equilibrium states

NASA Astrophysics Data System (ADS)

Tovbin, Yu. K.

2017-08-01

The possibility of obtaining analytical estimates in a diffusion approximation of the times needed by nonequilibrium small bodies to relax to their equilibrium states based on knowledge of the mass transfer coefficient is considered. This coefficient is expressed as the product of the self-diffusion coefficient and the thermodynamic factor. A set of equations for the diffusion transport of mixture components is formulated, characteristic scales of the size of microheterogeneous phases are identified, and effective mass transfer coefficients are constructed for them. Allowing for the developed interface of coexisting and immiscible phases along with the porosity of solid phases is discussed. This approach can be applied to the diffusion equalization of concentrations of solid mixture components in many physicochemical systems: the mutual diffusion of components in multicomponent systems (alloys, semiconductors, solid mixtures of inert gases) and the mass transfer of an absorbed mobile component in the voids of a matrix consisting of slow components or a mixed composition of mobile and slow components (e.g., hydrogen in metals, oxygen in oxides, and the transfer of molecules through membranes of different natures, including polymeric).

Phase equilibria and crystal chemistry of the CaO-1/2 >Nd2O3-CoOz system at 885 °C in air

NASA Astrophysics Data System (ADS)

Wong-Ng, W.; Laws, W.; Talley, K. R.; Huang, Q.; Yan, Y.; Martin, J.; Kaduk, J. A.

2014-07-01

The phase diagram of the CaO-1/2 >Nd2O3-CoOz system at 885 °C in air has been determined. The system consists of two calcium cobaltate compounds that have promising thermoelectric properties, namely, the 2D thermoelectric oxide solid solution, (Ca3-xNdx)Co4O9-z (0≤x≤0.5), which has a misfit layered structure, and Ca3Co2O6 which consists of 1D chains of alternating CoO6 trigonal prisms and CoO6 octahedra. Ca3Co2O6 was found to be a point compound without the substitution of Nd on the Ca site. The reported Nd2CoO4 phase was not observed at 885 °C. A ternary (Ca1-xNd1+x)CoO4-z (x=0) phase, or (CaNdCo)O4-z, was found to be stable at this temperature. A solid solution region of distorted perovskite (Nd1-xCax)CoO3-z (0≤x≤0.25, space group Pnma) was established. In the peripheral binary systems, while a solid solution region was identified for (Nd1-xCax)2O3-z (0≤x≤0.2), Nd was not found to substitute in the Ca site of CaO. Six solid solution tie-line regions and six three-phase regions were determined in the CaO-Nd2O3-CoOz system in air.

Using colloidal silica as isolator, diverter and blocking agent for subsurface geological applications

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

Bourcier, William L.; Roberts, Sarah K.; Roberts, Jeffery J.

A system for blocking fast flow paths in geological formations includes preparing a solution of colloidal silica having a nonviscous phase and a solid gel phase. The solution of colloidal silica is injected into the geological formations while the solution of colloidal silica is in the nonviscous phase. The solution of colloidal silica is directed into the fast flow paths and reaches the solid gel phase in the fast flow paths thereby blocking flow of fluid in the fast paths.

Reaction paths and equilibrium end-points in solid-solution aqueous-solution systems

USGS Publications Warehouse

Glynn, P.D.; Reardon, E.J.; Plummer, Niel; Busenberg, E.

1990-01-01

Equations are presented describing equilibrium in binary solid-solution aqueous-solution (SSAS) systems after a dissolution, precipitation, or recrystallization process, as a function of the composition and relative proportion of the initial phases. Equilibrium phase diagrams incorporating the concept of stoichiometric saturation are used to interpret possible reaction paths and to demonstrate relations between stoichiometric saturation, primary saturation, and thermodynamic equilibrium states. The concept of stoichiometric saturation is found useful in interpreting and putting limits on dissolution pathways, but there currently is no basis for possible application of this concept to the prediction and/ or understanding of precipitation processes. Previously published dissolution experiments for (Ba, Sr)SO4 and (Sr, Ca)C??O3orth. solids are interpreted using equilibrium phase diagrams. These studies show that stoichiometric saturation can control, or at least influence, initial congruent dissolution pathways. The results for (Sr, Ca)CO3orth. solids reveal that stoichiometric saturation can also control the initial stages of incongruent dissolution, despite the intrinsic instability of some of the initial solids. In contrast, recrystallisation experiments in the highly soluble KCl-KBr-H2O system demonstrate equilibrium. The excess free energy of mixing calculated for K(Cl, Br) solids is closely modeled by the relation GE = ??KBr??KClRT[a0 + a1(2??KBr-1)], where a0 is 1.40 ?? 0.02, a1, is -0.08 ?? 0.03 at 25??C, and ??KBr and ??KCl are the mole fractions of KBr and KCl in the solids. The phase diagram constructed using this fit reveals an alyotropic maximum located at ??KBr = 0.676 and at a total solubility product, ???? = [K+]([Cl-] + [Br-]) = 15.35. ?? 1990.

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.

Development of solid self-emulsifying drug delivery system (SEDDS) I: use of poloxamer 188 as both solidifying and emulsifying agent for lipids.

PubMed

Shah, Ankita V; Serajuddin, Abu T M

2012-10-01

To develop solid self-emulsifying drug delivery systems (SEDDS) for lipids using poloxamer 188 as both solidifying and emulsifying agents. Mixtures of various lipids with poloxamer 188 and PEG 8000 were prepared at ~75°C. The molten mixtures, with and without dissolved drugs (fenofibrate and probucol), were then cooled to room temperature. When solids formed, they were characterized by powder XRD, DSC, microscopy using cross-polarization and confocal fluorescence techniques, dispersion test in water and particle size analysis of dispersions. When mixed with poloxamer 188 or PEG 8000, lipids consisting of monoesters of fatty acids with glycerol or propylene glycol formed solid systems, but not di- and tri-esters, which showed phase separation. Added to water, the solid systems containing poloxamer 188 started to disperse in water forming oil globules of 200-600 nm. No emulsification of lipids was observed from solids containing PEG 8000, indicating that the surfactant property of poloxamer 188 was responsible for emulsification. Powder XRD, DSC and microscopic examination revealed that poloxamer 188 and PEG 8000 maintained their crystallinity in solid systems, while the lipids were interspersed in between crystalline regions. The drug remained solubilized in the lipid phase. A novel solid SEDDS is developed where the drug can be solubilized in liquid lipids and then the lipidic solution can be converted to solid mass by dispersing into the microstructure of poloxamer 188.

Singles correlation energy contributions in solids

NASA Astrophysics Data System (ADS)

Klimeš, Jiří; Kaltak, Merzuk; Maggio, Emanuele; Kresse, Georg

2015-09-01

The random phase approximation to the correlation energy often yields highly accurate results for condensed matter systems. However, ways how to improve its accuracy are being sought and here we explore the relevance of singles contributions for prototypical solid state systems. We set out with a derivation of the random phase approximation using the adiabatic connection and fluctuation dissipation theorem, but contrary to the most commonly used derivation, the density is allowed to vary along the coupling constant integral. This yields results closely paralleling standard perturbation theory. We re-derive the standard singles of Görling-Levy perturbation theory [A. Görling and M. Levy, Phys. Rev. A 50, 196 (1994)], highlight the analogy of our expression to the renormalized singles introduced by Ren and coworkers [Phys. Rev. Lett. 106, 153003 (2011)], and introduce a new approximation for the singles using the density matrix in the random phase approximation. We discuss the physical relevance and importance of singles alongside illustrative examples of simple weakly bonded systems, including rare gas solids (Ne, Ar, Xe), ice, adsorption of water on NaCl, and solid benzene. The effect of singles on covalently and metallically bonded systems is also discussed.

Plutonium partitioning in three-phase systems with water, granite grains, and different colloids.

PubMed

Xie, Jinchuan; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei; Zhou, Guoqing

2014-01-01

Low-solubility contaminants with high affinity for colloid surfaces may form colloid-associated species. The mobile characteristics of this species are, however, ignored by the traditional sorption/distribution experiments in which colloidal species contributed to the immobile fraction of the contaminants retained on the solids as a result of centrifugation or ultrafiltration procedures. The mobility of the contaminants in subsurface environments might be underestimated accordingly. Our results show that colloidal species of (239)Pu in three-phase systems remained the highest percentages in comparison to both the dissolved species and the immobile species retained on the granite grains (solid phase), although the relative fraction of these three species depended on the colloid types. The real solid/liquid distribution coefficients (K s/d) experimentally determined were generally smaller than the traditional K s/d (i.e., the K s+c/d in this study) by ~1,000 mL/g for the three-phase systems with the mineral colloids (granite particle, soil colloid, or kaolinite colloid). For the humic acid system, the traditional K s/d was 140 mL/g, whereas the real K s/d was approximately zero. The deviations from the real solid/liquid K s/d were caused by the artificially increased immobile fraction of Pu. One has to be cautious in using K s/d-based transport models to predict the fate and transport of Pu in the environment.

Surface Premelting Coupled with Bulk Phase Transitions in Colloidal Crystals

NASA Astrophysics Data System (ADS)

Li, Bo; Wang, Feng; Zhou, Di; Cao, Xin; Peng, Yi; Ni, Ran; Liao, Maijia; Han, Yilong

2015-03-01

Colloids have been used as outstanding model systems for the studies of various phase transitions in bulk, but not at interface yet. Here we obtained equilibrium crystal-vapor interfaces using tunable attractive colloidal spheres and studied the surface premelting at the single-particle level by video microscopy. We found that monolayer crystals exhibit a bulk isostructural solid-solid transition which triggers the surface premelting. The premelting is incomplete due to the interruption of a mechanical-instability-induced bulk melting. By contrast, two- or multilayer crystals do not have the solid-solid transition and the mechanical instability, hence they exhibit complete premelting with divergent surface-liquid thickness. These novel interplays between bulk and surface phase transitions cast new lights for both types of transitions.

On the mechanical stability of the body-centered cubic phase and the emergence of a metastable cI16 phase in classical hard sphere solids

NASA Astrophysics Data System (ADS)

Warshavsky, Vadim B.; Ford, David M.; Monson, Peter A.

2018-01-01

The stability of the body-centered cubic (bcc) solid phase of classical hard spheres is of intrinsic interest and is also relevant to the development of perturbation theories for bcc solids of other model systems. Using canonical ensemble Monte Carlo, we simulated systems initialized in a perfect bcc lattice at various densities in the solid region. We observed that the systems rapidly evolved into one of four structures that then persisted for the duration of the simulation. Remarkably, one of these structures was identified as cI16, a cubic crystalline structure with 16 particles in the unit cell, which has recently been observed experimentally in lithium and sodium solids at high pressures. The other three structures do not exhibit crystalline order but are characterized by common patterns in the radial distribution function and bond-orientational order parameter distribution; we refer to them as bcc-di, with i ranging from 1 to 3. We found similar outcomes when employing any of the three single occupancy cell (SOC) restrictions commonly used in the literature. We also ran long constant-pressure simulations with box shape fluctuations initiated from bcc and cI16 initial configurations. At lower pressures, all the systems evolved to defective face-centered cubic (fcc) or hexagonal close-packed (hcp) structures. At higher pressures, most of the systems initiated as bcc evolved to cI16 with some evolving to defective fcc/hcp. High pressure systems initiated from cI16 remained in that structure. We computed the chemical potential of cI16 using the Einstein crystal reference method and found that it is higher than that of fcc by ˜0.5kT-2.5kT over the pressure range studied, with the difference increasing with pressure. We find that the undistorted bcc solid, even with constant-volume and SOC restrictions applied, is so mechanically unstable that it is unsuitable for consideration as a metastable phase or as a reference system for studying bcc phases of other systems. On the other hand, cI16 is a mechanically stable structure that can spontaneously emerge from a bcc starting point but it is thermodynamically metastable relative to fcc or hcp.

Development of clinical dosage forms for a poorly water-soluble drug II: formulation and characterization of a novel solid microemulsion preconcentrate system for oral delivery of a poorly water-soluble drug.

PubMed

Li, Ping; Hynes, Sara R; Haefele, Thomas F; Pudipeddi, Madhu; Royce, Alan E; Serajuddin, Abu T M

2009-05-01

The solution of a poorly water-soluble drug in a liquid lipid-surfactant mixture, which served as a microemulsion preconcentrate, was converted into a solid form by incorporating it in a solid polyethylene glycol (PEG) matrix. The solid microemulsion preconcentrates thus formed consisted of Capmul PG8 (propylene glycol monocaprylate) as oil, Cremophor EL (polyoxyl 35 castor oil) as surfactant, and hydrophilic polymer PEG 3350 as solid matrix. The drug (aqueous solubility: 0.17 microg/mL at pH 1-8 and 25 degrees C) was dissolved in a melt of the mixture at 65-70 degrees C and then the hot solution was filled into hard gelatin capsules; the liquid gradually solidified upon cooling below 55 degrees C. The solid system was characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), confocal Raman microscopy (CRM), and the dispersion testing in water. It was confirmed that a solid microemulsion preconcentrate is a two-phase system, where clusters of crystalline PEG 3350 formed the solid structure (m.p. 55-60 degrees C) and the liquid microemulsion preconcentrate dispersed in between PEG 3350 crystals as a separate phase. The drug remained dissolved in the liquid phase. In vitro release testing showed that the preconcentrate dispersed readily in water forming a microemulsion with the drug dissolved in the oil particles (<150 nm) and the presence of PEG 3350 did not interfere with the process of self-microemulsification.

Habitable Planets with Dynamic System of Global Air-Liquid-Solid Planet and Life

NASA Astrophysics Data System (ADS)

Miura, Y.; Kato, T.

2017-11-01

Habitable zone is dynamic three phase states (air-liquid-solid), which will be obtained in water-planet with volatile exchanges. Water and carbon-bearing grains at older extraterrestrial stones suggest that there are no global ocean water system.

Melting of Simple Solids and the Elementary Excitations of the Communal Entropy

NASA Astrophysics Data System (ADS)

Bongiorno, Angelo

2010-03-01

The melting phase transition of simple solids is addressed through the use of atomistic computer simulations. Three transition metals (Ni, Au, and Pt) and a semiconductor (Si) are considered in this study. Iso-enthalpic molecular dynamics simulations are used to compute caloric curves across the solid-to-liquid phase transition of a periodic crystalline system, to construct the free energy function of the solid and liquid phases, and thus to derive the thermodynamical limit of the melting point, latent heat and entropy of fusion of the material. The computational strategy used in this study yields accurate estimates of melting parameters, it consents to determine the superheating and supercooling temperature limits, and it gives access to the atomistic mechanisms mediating the melting process. In particular, it is found that the melting phase transition in simple solids is driven by exchange steps involving a few atoms and preserving the crystalline structure. These self-diffusion phenomena correspond to the elementary excitations of the communal entropy and, as their rate depends on the local material cohesivity, they mediate both the homogeneous and non-homogeneous melting process in simple solids.

A Simple Approach to Characterize Gas-Aqueous Liquid Two-phase Flow Configuration Based on Discrete Solid-Liquid Contact Electrification.

PubMed

Choi, Dongwhi; Lee, Donghyeon; Kim, Dong Sung

2015-10-14

In this study, we first suggest a simple approach to characterize configuration of gas-aqueous liquid two-phase flow based on discrete solid-liquid contact electrification, which is a newly defined concept as a sequential process of solid-liquid contact and successive detachment of the contact liquid from the solid surface. This approach exhibits several advantages such as simple operation, precise measurement, and cost-effectiveness. By using electric potential that is spontaneously generated by discrete solid-liquid contact electrification, the configurations of the gas-aqueous liquid two-phase flow such as size of a gas slug and flow rate are precisely characterized. According to the experimental and numerical analyses on parameters that affect electric potential, gas slugs have been verified to behave similarly to point electric charges when the measuring point of the electric potential is far enough from the gas slug. In addition, the configuration of the gas-aqueous liquid two-phase microfluidic system with multiple gas slugs is also characterized by using the presented approach. For a proof-of-concept demonstration of using the proposed approach in a self-triggered sensor, a gas slug detector with a counter system is developed to show its practicality and applicability.

Dense Carbon Monoxide to 160 GPa: Stepwise Polymerization to Two-Dimensional Layered Solid

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

Ryu, Young-Jay; Kim, Minseob; Lim, Jinhyuk

Carbon monoxide (CO) is the first molecular system found to transform into a nonmolecular “polymeric” solid above 5.5 GPa, yet been studied beyond 10 GPa. Here, we show a series of pressure-induced phase transformations in CO to 160 GPa: from a molecular solid to a highly colored, low-density polymeric phase I to translucent, high-density phase II to transparent, layered phase III. The properties of these phases are consistent with those expected from recently predicted 1D P2 1/m, 3D I2 12 12 1, and 2D Cmcm structures, respectively. Thus, the present results advocate a stepwise polymerization of CO triple bonds tomore » ultimately a 2D singly bonded layer structure with an enhanced ionic character.« less

Thermodynamics of strongly coupled repulsive Yukawa particles in ambient neutralizing plasma: Thermodynamic instability and the possibility of observation in fine particle plasmas

NASA Astrophysics Data System (ADS)

Totsuji, Hiroo

2008-07-01

The thermodynamics is analyzed for a system composed of particles with hard cores, interacting via the repulsive Yukawa potential (Yukawa particulates), and neutralizing ambient (background) plasma. An approximate equation of state is given with proper account of the contribution of ambient plasma and it is shown that there exists a possibility for the total isothermal compressibility of Yukawa particulates and ambient plasma to diverge when the coupling between Yukawa particulates is sufficiently strong. In this case, the system undergoes a transition into separated phases with different densities and we have a critical point for this phase separation. Examples of approximate phase diagrams related to this transition are given. It is emphasized that the critical point can be in the solid phase and we have the possibility to observe a solid-solid phase separation. The applicability of these results to fine particle plasmas is investigated. It is shown that, though the values of the characteristic parameters are semiquantitative due to the effects not described by this model, these phenomena are expected to be observed in fine particle plasmas, when approximately isotropic bulk systems are realized with a very strong coupling between fine particles.

Nonstoichiometric fluorides—Solid electrolytes for electrochemical devices: A review

NASA Astrophysics Data System (ADS)

Sorokin, N. I.; Sobolev, B. P.

2007-09-01

The solid electrolytes with fluorine-ion conductivity that were revealed during the analysis of the phase diagrams of the MF m - RF n systems within the program of search for new multicomponent fluoride crystalline materials carried out at the Shubnikov Institute of Crystallography, Russian Academy of Sciences, are described. The most widespread and promising materials are the nonstoichiometric phases with fluorite (CaF2) and tysonite (LaF3) structures, which are formed in the MF2- RF3 systems ( M = Ca, Sr, Ba, Cd, or Pb; R = Sc, Y, or La-Lu). These phases have superionic fluorine conductivity due to the anion sublattice disorder. The ionic conductivity of crystals of both structure types has been studied and the limits of its change with composition and temperature are determined. Nonstoichiometric fluorides are used as solid electrolytes in chemical sensors, fluorine sources, and batteries. The prospects of the use of fluorine-ion conductors in solid-state electrochemical devices, principles of their operation, and the problems of optimization of their composition are discussed.

Survey of dissolved air flotation system efficiency for reduce of pollution of vegetable oil industry wastewater.

PubMed

Keramati, H; Alidadi, H; Parvaresh, A R; Movahedian, H; Mahvi, A H

2008-10-01

The aim of this research was to sudy the reduction of pollution of vegetable oil manufacturing wastewater with DAF system. At first phase of this examination, the optimum dosage of the coagulants was determined. The coagulants that used in this study were Alum and Ferric Chloride. The second phase was flotation in this series of examinations, oil, COD, total solid, volatile solid, fixed solid and suspended solid measured in raw wastewater and the effluent of the DAF pilot. Optimum value of pH for alum and ferric chloride obtained 7.5 and 5.5, respectively. Optimum dosage for these obtained 30 and 32 mg L(-1) in this research. Mean removal for the parameters ofoil, COD, total solid, volatile solid, fixed solid and suspended solid obtained 75.85, 78.27, 77.32, 82.47, 73.52 and 85.53%, respectively. With pressure rising from 3 to 4 and 5 atm removing rate of COD, total solid, volatile solid, fixed solid parameters reduced, but oil and suspended solid have increase. In addition, following increase of flotation time up to 120 sec all of the measured parameters have increase in removing rate. Optimum A/S for removal of COD, total solid, volatile solid, fixed solid parameters obtained 0.001 and for oil and suspended solid obtained 0.0015.

Numerical investigation of influence on heat transfer characteristics to pneumatically conveyed dense phase flow by selecting models and boundary conditions

NASA Astrophysics Data System (ADS)

Zheng, Y.; Liu, Q.; Li, Y.

2012-03-01

Solids moving with a gas stream in a pipeline can be found in many industrial processes, such as power generation, chemical, pharmaceutical, food and commodity transfer processes. A mass flow rate of the solids is important characteristic that is often required to be measured (and controlled) to achieve efficient utilization of energy and raw materials in pneumatic conveying systems. The methods of measuring the mass flow rate of solids in a pneumatic pipeline can be divided into direct and indirect (inferential) measurements. A thermal solids' mass flow-meter, in principle, should ideally provide a direct measurement of solids flow rate, regardless of inhomogeneities in solids' distribution and environmental impacts. One key issue in developing a thermal solids' mass flow-meter is to characterize the heat transfer between the hot pipe wall and the gas-solids dense phase flow. The Eulerian continuum modeling with gas-solid two phases is the most common method for pneumatic transport. To model a gas-solid dense phase flow passing through a heated region, the gas phase is described as a continuous phase and the particles as the second phase. This study aims to describe the heat transfer characteristics between the hot wall and the gas-solids dense phase flow in pneumatic pipelines by modeling a turbulence gas-solid plug passing through the heated region which involves several actual and crucial issues: selections of interphase exchange coefficient, near-wall region functions and different wall surface temperatures. A sensitivity analysis was discussed to identify the influence on the heat transfer characteristics by selecting different interphase exchange coefficient models and different boundary conditions. Simulation results suggest that sensitivity analysis in the choice of models is very significant. The simulation results appear to show that a combination of choosing the Syamlal-O'Brien interphase exchange coefficient model and the standard k-ɛ model along with the standard wall function model might be the best approach, by which, the simulation data seems to be closest to the experimental results.

The Uhlenbeck-Ford model: Exact virial coefficients and application as a reference system in fluid-phase free-energy calculations

NASA Astrophysics Data System (ADS)

Paula Leite, Rodolfo; Freitas, Rodrigo; Azevedo, Rodolfo; de Koning, Maurice

2016-11-01

The Uhlenbeck-Ford (UF) model was originally proposed for the theoretical study of imperfect gases, given that all its virial coefficients can be evaluated exactly, in principle. Here, in addition to computing the previously unknown coefficients B11 through B13, we assess its applicability as a reference system in fluid-phase free-energy calculations using molecular simulation techniques. Our results demonstrate that, although the UF model itself is too soft, appropriately scaled Uhlenbeck-Ford (sUF) models provide robust reference systems that allow accurate fluid-phase free-energy calculations without the need for an intermediate reference model. Indeed, in addition to the accuracy with which their free energies are known and their convenient scaling properties, the fluid is the only thermodynamically stable phase for a wide range of sUF models. This set of favorable properties may potentially put the sUF fluid-phase reference systems on par with the standard role that harmonic and Einstein solids play as reference systems for solid-phase free-energy calculations.

Solid/liquid phase diagram of the ammonium sulfate/glutaric acid/water system.

PubMed

Beyer, Keith D; Pearson, Christian S; Henningfield, Drew S

2013-05-02

We have studied the low temperature phase diagram and water activities of the ammonium sulfate/glutaric acid/water system using differential scanning calorimetry, infrared spectroscopy of thin films, and a new technique: differential scanning calorimetry-video microscopy. Using these techniques, we have determined that there is a temperature-dependent kinetic effect to the dissolution of glutaric acid in aqueous solution. We have mapped the solid/liquid ternary phase diagram, determined the water activities based on the freezing point depression, and determined the ice/glutaric acid phase boundary as well as the ternary eutectic composition and temperature. We have also modified our glutaric acid/water binary phase diagram previously published based on these new results. We compare our results for the ternary system to the predictions of the Extended AIM Aerosol Thermodynamics Model (E-AIM), and find good agreement for the ice melting points in the ice primary phase field of this system; however, significant differences were found with respect to phase boundaries, concentration and temperature of the ternary eutectic, and glutaric acid dissolution.

High-temperature experimental and thermodynamic modelling research on the pyrometallurgical processing of copper

NASA Astrophysics Data System (ADS)

Hidayat, Taufiq; Shishin, Denis; Decterov, Sergei A.; Hayes, Peter C.; Jak, Evgueni

2017-01-01

Uncertainty in the metal price and competition between producers mean that the daily operation of a smelter needs to target high recovery of valuable elements at low operating cost. Options for the improvement of the plant operation can be examined and decision making can be informed based on accurate information from laboratory experimentation coupled with predictions using advanced thermodynamic models. Integrated high-temperature experimental and thermodynamic modelling research on phase equilibria and thermodynamics of copper-containing systems have been undertaken at the Pyrometallurgy Innovation Centre (PYROSEARCH). The experimental phase equilibria studies involve high-temperature equilibration, rapid quenching and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA). The thermodynamic modelling deals with the development of accurate thermodynamic database built through critical evaluation of experimental data, selection of solution models, and optimization of models parameters. The database covers the Al-Ca-Cu-Fe-Mg-O-S-Si chemical system. The gas, slag, matte, liquid and solid metal phases, spinel solid solution as well as numerous solid oxide and sulphide phases are included. The database works within the FactSage software environment. Examples of phase equilibria data and thermodynamic models of selected systems, as well as possible implementation of the research outcomes to selected copper making processes are presented.

Solid-liquid critical behavior of water in nanopores.

PubMed

Mochizuki, Kenji; Koga, Kenichiro

2015-07-07

Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid-liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature-pressure-diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid-liquid critical phenomena of nanoconfined water. Solid-liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid-liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line.

Solid Polymer Electrolyte (SPE) fuel cell technology program

NASA Technical Reports Server (NTRS)

1979-01-01

The overall objectives of the Phase IV Solid Polymer Electrolyte Fuel Cell Technology Program were to: (1) establish fuel cell life and performance at temperatures, pressures and current densities significantly higher than those previously demonstrated; (2) provide the ground work for a space energy storage system based on the solid polymer electrolyte technology (i.e., regenerative H2/O2 fuel cell); (3) design, fabricate and test evaluate a full-scale single cell unit. During this phase, significant progress was made toward the accomplishment of these objectives.

Physico-Chemical Properties and Phase Behaviour of Pyrrolidinium-Based Ionic Liquids

PubMed Central

Domańska, Urszula

2010-01-01

A review of the relevant literature on 1-alkyl-1-methylpyrrolidinium-based ionic liquids has been presented. The phase diagrams for the binary systems of {1-ethyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate) [EMPYR][CF3SO3] + water, or + 1-butanol} and for the binary systems of {1-propyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate) [PMPYR][CF3SO3] + water, or + an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol)} have been determined at atmospheric pressure using a dynamic method. The influence of alcohol chain length was discussed for the [PMPYR][CF3SO3]. A systematic decrease in the solubility was observed with an increase of the alkyl chain length of an alcohol. (Solid + liquid) phase equilibria with complete miscibility in the liquid phase region were observed for the systems involving water and alcohols. The solubility of the ionic liquid increases as the alkyl chain length on the pyrrolidinium cation increases. The correlation of the experimental data has been carried out using the Wilson, UNIQUAC and the NRTL equations. The phase diagrams reported here have been compared to the systems published earlier with the 1-alkyl-1-methylpyrrolidinium-based ionic liquids. The influence of the cation and anion on the phase behaviour has been discussed. The basic thermal properties of pure ILs, i.e., melting temperature and the enthalpy of fusion, the solid-solid phase transition temperature and enthalpy have been measured using a differential scanning microcalorimetry technique. PMID:20480044

Two-phase non-Newtonian hydrodynamic modeling of slurries

NASA Astrophysics Data System (ADS)

Wang, C. S.; Lyczkowski, R. W.; Berry, G. F.

The two-phase hydrodynamic theory of fluid/solid flow has been extended to incorporate the constitutive relationship for power-law non-Newtonian behavior. A model has been developed to predict the spatial and temporal variations in solids and liquid velocities and concentration of non-Newtonian slurries under high shear rates in diesel engine injection systems. Comparisons between the present non-Newtonian two-phase theory and the conventional theory have also been made. Selected results for diesel injection nozzle applications are presented. The results from this model can be used to calculate directly the erosion rates at the nozzle boundaries and the solids loading at the nozzle exit.

Nanostructure Formation by controlled dewetting on patterned substrates: A combined theoretical, modeling and experimental study.

PubMed

Lu, Liang-Xing; Wang, Ying-Min; Srinivasan, Bharathi Madurai; Asbahi, Mohamed; Yang, Joel K W; Zhang, Yong-Wei

2016-09-01

We perform systematic two-dimensional energetic analysis to study the stability of various nanostructures formed by dewetting solid films deposited on patterned substrates. Our analytical results show that by controlling system parameters such as the substrate surface pattern, film thickness and wetting angle, a variety of equilibrium nanostructures can be obtained. Phase diagrams are presented to show the complex relations between these system parameters and various nanostructure morphologies. We further carry out both phase field simulations and dewetting experiments to validate the analytically derived phase diagrams. Good agreements between the results from our energetic analyses and those from our phase field simulations and experiments verify our analysis. Hence, the phase diagrams presented here provide guidelines for using solid-state dewetting as a tool to achieve various nanostructures.

Two phase microstructure for Ag-Ni nanowires

NASA Astrophysics Data System (ADS)

Srivastava, Chandan; Rai, Rajesh Kumar

2013-03-01

In the present study, electrodeposition technique was used to produce Ag-Ni nanowires. Ag-Ni system shows extremely high bulk immiscibility. Nanowire morphology was achieved by employing an anodic alumina membrane having pores of ˜200 nm diameter. Microstructure of as-deposited wire was composed of nano-sized solid solution structured Ag-Ni nanoparticles embedded in a matrix of pure Ag phase. It is proposed that the two phase microstructure resulted from an initial formation of solid solution structured nanoparticles in the alumina template pore followed by nucleation of pure Ag phase over the particles which eventually grew to form the matrix phase.

Impact of the volume of gaseous phase in closed reactors on ANC results and modelling

NASA Astrophysics Data System (ADS)

Drapeau, Clémentine; Delolme, Cécile; Lassabatere, Laurent; Blanc, Denise

2016-04-01

The understanding of the geochemical behavior of polluted solid materials is often challenging and requires huge expenses of time and money. Nevertheless, given the increasing amounts of polluted solid materials and related risks for the environment, it is more and more crucial to understand the leaching of majors and trace metals elements from these matrices. In the designs of methods to quantify pollutant solubilization, the combination of experimental procedures with modeling approaches has recently gained attention. Among usual methods, some rely on the association of ANC and geochemical modeling. ANC experiments - Acid Neutralization Capacity - consists in adding known quantities of acid or base to a mixture of water and contaminated solid materials at a given liquid / solid ratio in closed reactors. Reactors are agitated for 48h and then pH, conductivity, redox potential, carbon, majors and heavy metal solubilized are quantified. However, in most cases, the amounts of matrix and water do not reach the total volume of reactors, leaving some space for air (gaseous phase). Despite this fact, no clear indication is given in standard procedures about the effect of this gaseous phase. Even worse, the gaseous phase is never accounted for when exploiting or modeling ANC data. The gaseous phase may exchange CO2 with the solution, which may, in turn, impact both pH and element release. This study lies within the most general framework for the use of geochemical modeling for the prediction of ANC results for the case of pure phases to real phase assemblages. In this study, we focus on the effect of the gaseous phase on ANC experiments on different mineral phases through geochemical modeling. To do so, we use PHREEQC code to model the evolution of pH and element release (including majors and heavy metals) when several matrices are put in contact with acid or base. We model the following scenarios for the gaseous phase: no gas, contact with the atmosphere (open system) and real reactors conditions (semi-closed systems). The solid phases tested are pure phases (calcite, sulfides, etc.) and synthetic assemblages mimicking complex polluted matrices. The modeling clearly shows that the systems are sensitive to the opening to the atmosphere. If the open system and the system with no gas are entirely different, "real" reactors also differ significantly from the other systems. Apparently, the presence of the gaseous phase in reactors greatly impacts pH and element release. This parameter should be accounted for in ANC experimental procedures and modeling. In addition to this numerical study, experimental results, previously obtained for urban polluted sediments, are analyzed in lights of the findings of the numerical study. This step allows us to strengthen conclusions and to pinpoint at the necessity to account for the gaseous phase when performing and modeling ANC experiments.

Solid state high resolution multi-spectral imager CCD test phase

NASA Technical Reports Server (NTRS)

1973-01-01

The program consisted of measuring the performance characteristics of charge coupled linear imaging devices, and a study defining a multispectral imaging system employing advanced solid state photodetection techniques.

Estrogenic and AhR activities in dissolved phase and suspended solids from wastewater treatment plants.

PubMed

Dagnino, Sonia; Gomez, Elena; Picot, Bernadette; Cavaillès, Vincent; Casellas, Claude; Balaguer, Patrick; Fenet, Hélène

2010-05-15

The distribution of estrogen receptor (ERalpha) and Aryl Hydrocarbon Receptor (AhR) activities between the dissolved phase and suspended solids were investigated during wastewater treatment. Three wastewater treatment plants with different treatment technologies (waste stabilization ponds (WSPs), trickling filters (TFs) and activated sludge supplemented with a biofilter system (ASB)) were sampled. Estrogenic and AhR activities were detected in both phases in influents and effluents. Estrogenic and AhR activities in wastewater influents ranged from 41.8 to 79 ng/L E(2) Eq. and from 37.9 to 115.5 ng/L TCDD Eq. in the dissolved phase and from 5.5 to 88.6 ng/g E(2) Eq. and from 15 to 700 ng/g TCDD Eq. in the suspended solids. For both activities, WSP showed greater or similar removal efficiency than ASB and both were much more efficient than TF which had the lowest removal efficiency. Moreover, our data indicate that the efficiency of removal of ER and AhR activities from the suspended solid phase was mainly due to removal of suspended solids. Indeed, ER and AhR activities were detected in the effluent suspended solid phase indicating that suspended solids, which are usually not considered in these types of studies, contribute to environmental contamination by endocrine disrupting compounds and should therefore be routinely assessed for a better estimation of the ER and AhR activities released in the environment. Copyright 2010 Elsevier B.V. All rights reserved.

Phase Behavior of Binary Mixture of Heptaethylene Glycol Decyl Ether and Water: Formation of Phase Compound in Solid Phase

PubMed

Nibu; Suemori; Inoue

1997-07-01

Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to construct and characterize the phase diagram for a binary mixture of heptaethylene glycol decyl ether (C10 E7 ) and water in the temperature range from -60 to 80°C. Plots of the endothermic peak temperatures obtained by DSC measurements against compositions provided eutectic solid-liquid phase boundaries with a eutectic composition of 34 wt% of H2 O. On the other hand, heat of fusion per unit weight of the mixture changed discretely at the composition corresponding to the "eutectic" composition. Furthermore, the IR spectra obtained for the mixture in the solid phase were well reproduced as a superposition of those for the mixture of 34 wt% H2 O and pure components but were not reproduced by superimposing the spectra obtained for the solid surfactant and ice. These observations indicate that a solid phase compound is formed between C10 E7 and water with a stoichiometry of 1:14 and that the compound and pure components exist as separate phases, rather than the phases separating into surfactant and ice, which would be expected if the C10 E7 /water mixture formed a true eutectic mixture system. It is estimated from the composition corresponding to the phase compounds that two molecules of water per oxyethylene unit are bound to hydrophilic polyoxyethylene chain of C10 E7 to form a hydrated compound.

DEVELOPMENT OF LOW-DIFFUSION FLUX-SPLITTING METHODS FOR DENSE GAS-SOLID FLOWS

EPA Science Inventory

The development of a class of low-diffusion upwinding methods for computing dense gas-solid flows is presented in this work. An artificial compressibility/low-Mach preconditioning strategy is developed for a hyperbolic two-phase flow equation system consisting of separate solids ...

Nongeometric conditional phase shift via adiabatic evolution of dark eigenstates: a new approach to quantum computation.

PubMed

Zheng, Shi-Biao

2005-08-19

We propose a new approach to quantum phase gates via the adiabatic evolution. The conditional phase shift is neither of dynamical nor geometric origin. It arises from the adiabatic evolution of the dark state itself. Taking advantage of the adiabatic passage, this kind of quantum logic gates is robust against moderate fluctuations of experimental parameters. In comparison with the geometric phase gates, it is unnecessary to drive the system to undergo a desired cyclic evolution to obtain a desired solid angle. Thus, the procedure is simplified, and the fidelity may be further improved since the errors in obtaining the required solid angle are avoided. We illustrate such a kind of quantum logic gates in the ion trap system. The idea can also be realized in other systems, opening a new perspective for quantum information processing.

Mixed-order phase transition in a colloidal crystal.

PubMed

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-05

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field [Formula: see text] At the transition field [Formula: see text], the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length [Formula: see text] Mean-field critical exponents are predicted, since the upper critical dimension of the transition is [Formula: see text] Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

Mixed-order phase transition in a colloidal crystal

NASA Astrophysics Data System (ADS)

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-01

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2-Hs2|-1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

Composition design for Laves phase-related body-centered cubic-V solid solution alloys with large hydrogen storage capacities.

PubMed

Wang, H B; Wang, Q; Dong, C; Yuan, L; Xu, F; Sun, L X

2008-03-19

This paper analyzes the characteristics of alloy compositions with large hydrogen storage capacities in Laves phase-related body-centered cubic (bcc) solid solution alloy systems using the cluster line approach. Since a dense-packed icosahedral cluster A(6)B(7) characterizes the local structure of AB(2) Laves phases, in an A-B-C ternary system, such as Ti-Cr (Mn, Fe)-V, where A-B forms AB(2) Laves phases while A-C and B-C tend to form solid solutions, a cluster line A(6)B(7)-C is constructed by linking A(6)B(7) to C. The alloy compositions with large hydrogen storage capacities are generally located near this line and are approximately expressed with the cluster-plus-glue-atom model. The cluster line alloys (Ti(6)Cr(7))(100-x)V(x) (x = 2.5-70 at.%) exhibit different structures and hence different hydrogen storage capacities with increasing V content. The alloys (Ti(6)Cr(7))(95)V(5) and Ti(30)Cr(40)V(30) with bcc solid solution structure satisfy the cluster-plus-glue-atom model.

Uncovering the Connection Between Low-Frequency Dynamics and Phase Transformation Phenomena in Molecular Solids

NASA Astrophysics Data System (ADS)

Ruggiero, Michael T.; Zhang, Wei; Bond, Andrew D.; Mittleman, Daniel M.; Zeitler, J. Axel

2018-05-01

The low-frequency motions of molecules in the condensed phase have been shown to be vital to a large number of physical properties and processes. However, in the case of disordered systems, it is often difficult to elucidate the atomic-level details surrounding these phenomena. In this work, we have performed an extensive experimental and computational study on the molecular solid camphor, which exhibits a rich and complex structure-dynamics relationship, and undergoes an order-disorder transition near ambient conditions. The combination of x-ray diffraction, variable temperature and pressure terahertz time-domain spectroscopy, ab initio molecular dynamics, and periodic density functional theory calculations enables a complete picture of the phase transition to be obtained, inclusive of mechanistic, structural, and thermodynamic phenomena. Additionally, the low-frequency vibrations of a disordered solid are characterized for the first time with atomic-level precision, uncovering a clear link between such motions and the phase transformation. Overall, this combination of methods allows for significant details to be obtained for disordered solids and the associated transformations, providing a framework that can be directly applied for a wide range of similar systems.

Uncovering the Connection Between Low-Frequency Dynamics and Phase Transformation Phenomena in Molecular Solids.

PubMed

Ruggiero, Michael T; Zhang, Wei; Bond, Andrew D; Mittleman, Daniel M; Zeitler, J Axel

2018-05-11

The low-frequency motions of molecules in the condensed phase have been shown to be vital to a large number of physical properties and processes. However, in the case of disordered systems, it is often difficult to elucidate the atomic-level details surrounding these phenomena. In this work, we have performed an extensive experimental and computational study on the molecular solid camphor, which exhibits a rich and complex structure-dynamics relationship, and undergoes an order-disorder transition near ambient conditions. The combination of x-ray diffraction, variable temperature and pressure terahertz time-domain spectroscopy, ab initio molecular dynamics, and periodic density functional theory calculations enables a complete picture of the phase transition to be obtained, inclusive of mechanistic, structural, and thermodynamic phenomena. Additionally, the low-frequency vibrations of a disordered solid are characterized for the first time with atomic-level precision, uncovering a clear link between such motions and the phase transformation. Overall, this combination of methods allows for significant details to be obtained for disordered solids and the associated transformations, providing a framework that can be directly applied for a wide range of similar systems.

Evaluation of the slurry management strategy and the integration of the composting technology in a pig farm - Agronomical and environmental implications.

PubMed

Sáez, José A; Clemente, Rafael; Bustamante, M Ángeles; Yañez, David; Bernal, M Pilar

2017-05-01

The changes in livestock production systems towards intensification frequently lead to an excess of manure generation with respect to the agricultural land available for its soil application. However, treatment technologies can help in the management of manures, especially in N-surplus areas. An integrated slurry treatment system based on solid-liquid separation, aerobic treatment of the liquid and composting the solid fraction was evaluated in a pig farm (sows and piglets) in the South of Spain. Solid fraction separation using a filter band connected to a screw press had low efficiency (38%), which was greatly improved incorporating a rotatory sieve (61%). The depuration system was very efficient for the liquid, with total removal of 84% total solids, 87% volatile solids, and 98% phosphorus. Two composting systems were tested through mechanical turning of: 1- a mixture of solid fraction stored for 1 month after solid-liquid separation and cereal straw; 2- recently-separated solid fraction mixed with cotton gin waste. System 2 was recommended for the farm, as it exhibited a fast temperature rise and a long thermophilic phase to ensure compost sanitisation, and high recovery of nutrients (TN 77%, P and K > 85%) and organic matter (45%). The composts obtained were mature, stable and showed a high degree of humification of their organic matter, absence of phytotoxicity and concentrations of nutrients similar to other composts from pig manure or separated slurry solids. However, the introduction of slurry from piglets into the solid-liquid separation system should be avoided in order to reduce the content of Zn in the compost, which lowers its quality. The slurry separation followed by composting of the solid fraction using a passive windrow system, and aeration of the liquid phase, was the most recommendable procedure for the reduction of GHG emissions on the farm. Copyright © 2017 Elsevier Ltd. All rights reserved.

Si-Ge-metal ternary phase diagram calculations

NASA Technical Reports Server (NTRS)

Fleurial, J. P.; Borshchevsky, A.

1990-01-01

Solution crystal growth and doping conditions of Si-Ge alloys used for high-temperature thermoelectric generation are determined here. Liquid-phase epitaxy (LPE) has been successfully employed recently to obtain single-crystalline homogeneous layers of Si-Ge solid solutions from a liquid metal solvent. Knowledge of Si-Ge-metallic solvent ternary phase diagrams is essential for further single-crystal growth development. Consequently, a thermodynamic equilibrium model was used to calculate the phase diagrams of the Si-Ge-M systems, including solid solubilities, where M is Al, Ga, In, Sn, Pb, Sb, or Bi. Good agreement between calculated liquidus and solidus data and experimental DTA and microprobe results was obtained. The results are used to compare the suitability of the different systems for crystal growth (by LPE-type process).

New Density Functional Approach for Solid-Liquid-Vapor Transitions in Pure Materials

NASA Astrophysics Data System (ADS)

Kocher, Gabriel; Provatas, Nikolas

2015-04-01

A new phase field crystal (PFC) type theory is presented, which accounts for the full spectrum of solid-liquid-vapor phase transitions within the framework of a single density order parameter. Its equilibrium properties show the most quantitative features to date in PFC modeling of pure substances, and full consistency with thermodynamics in pressure-volume-temperature space is demonstrated. A method to control either the volume or the pressure of the system is also introduced. Nonequilibrium simulations show that 2- and 3-phase growth of solid, vapor, and liquid can be achieved, while our formalism also allows for a full range of pressure-induced transformations. This model opens up a new window for the study of pressure driven interactions of condensed phases with vapor, an experimentally relevant paradigm previously missing from phase field crystal theories.

The Effect of Electronic Structure on the Phases Present in High Entropy Alloys

PubMed Central

Leong, Zhaoyuan; Wróbel, Jan S.; Dudarev, Sergei L.; Goodall, Russell; Todd, Iain; Nguyen-Manh, Duc

2017-01-01

Multicomponent systems, termed High Entropy Alloys (HEAs), with predominantly single solid solution phases are a current area of focus in alloy development. Although different empirical rules have been introduced to understand phase formation and determine what the dominant phases may be in these systems, experimental investigation has revealed that in many cases their structure is not a single solid solution phase, and that the rules may not accurately distinguish the stability of the phase boundaries. Here, a combined modelling and experimental approach that looks into the electronic structure is proposed to improve accuracy of the predictions of the majority phase. To do this, the Rigid Band model is generalised for magnetic systems in prediction of the majority phase most likely to be found. Good agreement is found when the predictions are confronted with data from experiments, including a new magnetic HEA system (CoFeNiV). This also includes predicting the structural transition with varying levels of constituent elements, as a function of the valence electron concentration, n, obtained from the integrated spin-polarised density of states. This method is suitable as a new predictive technique to identify compositions for further screening, in particular for magnetic HEAs. PMID:28059106

The Effect of Electronic Structure on the Phases Present in High Entropy Alloys.

PubMed

Leong, Zhaoyuan; Wróbel, Jan S; Dudarev, Sergei L; Goodall, Russell; Todd, Iain; Nguyen-Manh, Duc

2017-01-06

Multicomponent systems, termed High Entropy Alloys (HEAs), with predominantly single solid solution phases are a current area of focus in alloy development. Although different empirical rules have been introduced to understand phase formation and determine what the dominant phases may be in these systems, experimental investigation has revealed that in many cases their structure is not a single solid solution phase, and that the rules may not accurately distinguish the stability of the phase boundaries. Here, a combined modelling and experimental approach that looks into the electronic structure is proposed to improve accuracy of the predictions of the majority phase. To do this, the Rigid Band model is generalised for magnetic systems in prediction of the majority phase most likely to be found. Good agreement is found when the predictions are confronted with data from experiments, including a new magnetic HEA system (CoFeNiV). This also includes predicting the structural transition with varying levels of constituent elements, as a function of the valence electron concentration, n, obtained from the integrated spin-polarised density of states. This method is suitable as a new predictive technique to identify compositions for further screening, in particular for magnetic HEAs.

Solid-liquid phase equilibria in the ternary system (LiBO2 + Li2CO3 + H2O) at 288.15 and 298.15 K

NASA Astrophysics Data System (ADS)

Wang, Shi-qiang; Guo, Ya-fei; Yang, Jian-sen; Deng, Tian-long

2015-12-01

Experimental studies on the solubilities and physicochemical properties including density, refractive index and pH value in the ternary systems (LiBO2 + Li2CO3 + H2O) at 288.15 and 298.15 K were determined with the method of isothermal dissolution equilibrium. Based on the experimental results, the phase diagrams and their corresponding physicochemical properties versus composition diagram in the system were plotted. In the phase diagrams of the ternary system at 288.15 and 298.15 K, there are one eutectic point and two crystallization regions corresponding to lithium metaborate octahydrate (LiBO2 · 8H2O) and lithium carbonate (Li2CO3), respectively. This system at both temperatures belongs to hydrate type I, and neither double salt nor solid solution was found. A comparison of the phase diagrams for this ternary system at 288.15 and 298.15 K shows that the solid phase numbers and exist minerals are the same, and the area of crystallization region of Li2CO3 is increased obviously with the increasing temperature while that of LiBO2 · 8H2O is decreased. The physicochemical properties (density, pH value and refractive index) of the solutions of the ternary system at two temperatures changes regularly with the increasing lithium carbonate concentration. The calculated values of density and refractive index using empirical equations of the ternary system are in good agreement with the experimental values.

Using reweighting and free energy surface interpolation to predict solid-solid phase diagrams

NASA Astrophysics Data System (ADS)

Schieber, Natalie P.; Dybeck, Eric C.; Shirts, Michael R.

2018-04-01

Many physical properties of small organic molecules are dependent on the current crystal packing, or polymorph, of the material, including bioavailability of pharmaceuticals, optical properties of dyes, and charge transport properties of semiconductors. Predicting the most stable crystalline form at a given temperature and pressure requires determining the crystalline form with the lowest relative Gibbs free energy. Effective computational prediction of the most stable polymorph could save significant time and effort in the design of novel molecular crystalline solids or predict their behavior under new conditions. In this study, we introduce a new approach using multistate reweighting to address the problem of determining solid-solid phase diagrams and apply this approach to the phase diagram of solid benzene. For this approach, we perform sampling at a selection of temperature and pressure states in the region of interest. We use multistate reweighting methods to determine the reduced free energy differences between T and P states within a given polymorph and validate this phase diagram using several measures. The relative stability of the polymorphs at the sampled states can be successively interpolated from these points to create the phase diagram by combining these reduced free energy differences with a reference Gibbs free energy difference between polymorphs. The method also allows for straightforward estimation of uncertainties in the phase boundary. We also find that when properly implemented, multistate reweighting for phase diagram determination scales better with the size of the system than previously estimated.

Thermodynamic assessment of the Sn-Co lead-free solder system

NASA Astrophysics Data System (ADS)

Liu, Libin; Andersson, Cristina; Liu, Johan

2004-09-01

The Sn-Co-Cu eutectic alloy can be a less expensive alternative for the Sn-Ag-Cu alloy. In order to find the eutectic solder composition of the Sn-Co-Cu system, the Sn-Co binary system has been thoroughly assessed with the calculation of phase diagram (CALPHAD) method. The liquid phase, the FCC and HCP Co-rich solid solution, and the BCT Sn-rich solid solution have been described by the Redlich-Kister model. The Hillert-Jarl-Inden model has been used to describe the magnetic contributions to Gibbs energy in FCC and HCP. The CoSn2, CoSn, Co3Sn2_β, and Co3Sn2_α phases have been treated as stoichiometric phases. A series of thermodynamic parameters have been obtained. The calculated phase diagram and thermodynamic properties are in good agreement with the experimental data. The obtained thermodynamic data was used to extrapolate the ternary Sn-Co-Cu phase diagram. The composition of the Sn-rich eutectic point of the Sn-Co-Cu system was found to be 224°C, 0.4% Co, and 0.7% Cu.

Perovskite solid solutions with multiferroic morphotropic phase boundaries and property enhancement

NASA Astrophysics Data System (ADS)

Algueró, M.; Amorín, H.; Fernández-Posada, C. M.; Peña, O.; Ramos, P.; Vila, E.; Castro, A.

2016-05-01

Recently, large phase-change magnetoelectric response has been anticipated by a first-principles investigation of phases in the BiFeO3-BiCoO3 perovskite binary system, associated with the existence of a discontinuous morphotropic phase boundary (MPB) between multiferroic polymorphs of rhombohedral and tetragonal symmetries. This might be a general property of multiferroic phase instabilities, and a novel promising approach for room temperature magnetoelectricity. We review here our current investigations on the identification and study of additional material systems, alternative to BiFeO3-BiCoO3 that has only been obtained by high pressure synthesis. Three systems, whose phase diagrams were, in principle, liable to show multiferroic MPBs have been addressed: the BiMnO3-PbTiO3 and BiFeO3-PbTiO3 binary systems, and the BiFeO3-BiMnO3-PbTiO3 ternary one. A comprehensive study of multiferroism across different solid solutions was carried out based on electrical and magnetic characterizations, complemented with mechanical and electromechanical measurements. An in-depth structural analysis was also accomplished when necessary.

Normal and anomalous nuclear spin-lattice relaxation at high temperatures in Sc-H(D), Y-H, and Lu-H solid solutions

NASA Astrophysics Data System (ADS)

Barnes, R. G.; Han, J.-W.; Torgeson, D. R.; Baker, D. B.; Conradi, M. S.; Norberg, R. E.

1995-02-01

We report the results of measurements of the proton (1H) spin-lattice relaxation rate R1 at high temperatures (to ~1400 K) in the hcp (α) solid-solution phases of the Sc-H, Y-H, and Lu-H systems, and of R1(45Sc) in Sc-H and Sc-D solid solutions. The latter measurements show unambiguous evidence of an anomalous increase at ~1000 K, whereas R1(1H) shows no such increase at any temperature. This behavior of R1(1H) contrasts with that in the bcc V-H, etc., solid solutions where anomalous relaxation occurs below ~1000 K, and in all investigated metal dihydride phases, MH2-x. The anomalous R1(1H) behavior in α-VHx, α-NbHx, etc., may be understood in terms of fast spin relaxation in the H2 gas in equilibrium with the solid, mediated by fast gas-solid exchange of hydrogen. However, in the present systems, α-ScHx, α-YHx, etc., the H2 gas pressure in equilibrium with the hcp systems is extremely low, resulting in negligible H2 concentration in the gas phase, and consequently a negligible contribution to R1(1H). In contrast, some of the present measurements indicate that the R1(45Sc) anomaly does result from the hydrogen content of the metal, but the mechanism remains unexplained.

Nanointerface-driven reversible hydrogen storage in the nanoconfined Li-N-H system

DOE PAGES

Wood, Brandon C.; Stavila, Vitalie; Poonyayant, Natchapol; ...

2017-01-20

Internal interfaces in the Li 3N/[LiNH 2 + 2LiH] solid-state hydrogen storage system alter the hydrogenation and dehydrogenation reaction pathways upon nanosizing, suppressing undesirable intermediate phases to dramatically improve kinetics and reversibility. Finally, the key role of solid interfaces in determining thermodynamics and kinetics suggests a new paradigm for optimizing complex hydrides for solid-state hydrogen storage by engineering internal microstructure.

Scalability study of solid xenon

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

Yoo, J.; Cease, H.; Jaskierny, W. F.

2015-04-01

We report a demonstration of the scalability of optically transparent xenon in the solid phase for use as a particle detector above a kilogram scale. We employed a cryostat cooled by liquid nitrogen combined with a xenon purification and chiller system. A modified {\\it Bridgeman's technique} reproduces a large scale optically transparent solid xenon.

Developpement de techniques numeriques pour l'estimation, la modelisation et la prediction de proprietes thermodynamiques et structurales de systems metalliques a fort ordonnancement chimique

NASA Astrophysics Data System (ADS)

Harvey, Jean-Philippe

In this work, the possibility to calculate and evaluate with a high degree of precision the Gibbs energy of complex multiphase equilibria for which chemical ordering is explicitly and simultaneously considered in the thermodynamic description of solid (short range order and long range order) and liquid (short range order) metallic phases is studied. The cluster site approximation (CSA) and the cluster variation method (CVM) are implemented in a new minimization technique of the Gibbs energy of multicomponent and multiphase systems to describe the thermodynamic behaviour of metallic solid solutions showing strong chemical ordering. The modified quasichemical model in the pair approximation (MQMPA) is also implemented in the new minimization algorithm presented in this work to describe the thermodynamic behaviour of metallic liquid solutions. The constrained minimization technique implemented in this work consists of a sequential quadratic programming technique based on an exact Newton’s method (i.e. the use of exact second derivatives in the determination of the Hessian of the objective function) combined to a line search method to identify a direction of sufficient decrease of the merit function. The implementation of a new algorithm to perform the constrained minimization of the Gibbs energy is justified by the difficulty to identify, in specific cases, the correct multiphase assemblage of a system where the thermodynamic behaviour of the equilibrium phases is described by one of the previously quoted models using the FactSage software (ex.: solid_CSA+liquid_MQMPA; solid1_CSA+solid2_CSA). After a rigorous validation of the constrained Gibbs energy minimization algorithm using several assessed binary and ternary systems found in the literature, the CVM and the CSA models used to describe the energetic behaviour of metallic solid solutions present in systems with key industrial applications such as the Cu-Zr and the Al-Zr systems are parameterized using fully consistent thermodynamic an structural data generated from a Monte Carlo (MC) simulator also implemented in the framework of this project. In this MC simulator, the modified embedded atom model in the second nearest neighbour formalism (MEAM-2NN) is used to describe the cohesive energy of each studied structure. A new Al-Zr MEAM-2NN interatomic potential needed to evaluate the cohesive energy of the condensed phases of this system is presented in this work. The thermodynamic integration (TI) method implemented in the MC simulator allows the evaluation of the absolute Gibbs energy of the considered solid or liquid structures. The original implementation of the TI method allowed us to evaluate theoretically for the first time all the thermodynamic mixing contributions (i.e., mixing enthalpy and mixing entropy contributions) of a metallic liquid (Cu-Zr and Al-Zr) and of a solid solution (face-centered cubic (FCC) Al-Zr solid solution) described by the MEAM-2NN. Thermodynamic and structural data obtained from MC and molecular dynamic simulations are then used to parameterize the CVM for the Al-Zr FCC solid solution and the MQMPA for the Al-Zr and the Cu-Zr liquid phase respectively. The extended thermodynamic study of these systems allow the introduction of a new type of configuration-dependent excess parameters in the definition of the thermodynamic function of solid solutions described by the CVM or the CSA. These parameters greatly improve the precision of these thermodynamic models based on experimental evidences found in the literature. A new parameterization approach of the MQMPA model of metallic liquid solutions is presented throughout this work. In this new approach, calculated pair fractions obtained from MC/MD simulations are taken into account as well as configuration-independent volumetric relaxation effects (regular like excess parameters) in order to parameterize precisely the Gibbs energy function of metallic melts. The generation of a complete set of fully consistent thermodynamic, physical and structural data for solid, liquid, and stoichiometric compounds and the subsequent parameterization of their respective thermodynamic model lead to the first description of the complete Al-Zr phase diagram in the range of composition [0 ≤ XZr ≤ 5 / 9] based on theoretical and fully consistent thermodynamic properties. MC and MD simulations are performed for the Al-Zr system to define for the first time the precise thermodynamic behaviour of the amorphous phase for its entire range of composition. Finally, all the thermodynamic models for the liquid phase, the FCC solid solution and the amorphous phase are used to define conditions based on thermodynamic and volumetric considerations that favor the amorphization of Al-Zr alloys.

Experimental study and thermodynamic modeling of the phase relation in the Fe-S-Si system with implications for the distribution of S and Si in a partially solidified core

NASA Astrophysics Data System (ADS)

Tao, R.; Fei, Y.

2017-12-01

Planetary cooling leads to solidification of any initially molten metallic core. Some terrestrial cores (e.g. Mercury) are formed and differentiated under relatively reduced conditions, and they are thought to be composed of Fe-S-Si. However, there are limited understanding of the phase relations in the Fe-S-Si system at high pressure and temperature. In this study, we conducted high-pressure experiments to investigate the phase relations in the Fe-S-Si system up to 25 GPa. Experimental results show that the liquidus and solidus in this study are slightly lower than those in the Fe-S binary system for the same S concentration in liquid at same pressure. The Fe3S, which is supposed to be the stable sub-solidus S-bearing phase in the Fe-S binary system above 17 GPa, is not observed in the Fe-S-Si system at 21 GPa. Almost all S prefers to partition into liquid, while the distribution of Si between solid and liquid depends on experimental P and T conditions. We obtained the partition coefficient log(KDSi) by fitting the experimental data as a function of P, T and S concentration in liquid. At a constant pressure, the log(KDSi) linearly decreases with 1/T(K). With increase of pressure, the slopes of linear correlation between log(KDSi) and 1/T(K) decreases, indicating that more Si partitions into solid at higher pressure. In order to interpolate and extrapolate the phase relations over a wide pressure and temperature range, we established a comprehensive thermodynamic model in the Fe-S-Si system. The results will be used to constrain the distribution of S and Si between solid inner core and liquid outer core for a range of planet sizes. A Si-rich solid inner core and a S-rich liquid outer core are suggested for an iron-rich core.

Space shuttle solid rocket booster recovery system definition, volume 1

NASA Technical Reports Server (NTRS)

1973-01-01

The performance requirements, preliminary designs, and development program plans for an airborne recovery system for the space shuttle solid rocket booster are discussed. The analyses performed during the study phase of the program are presented. The basic considerations which established the system configuration are defined. A Monte Carlo statistical technique using random sampling of the probability distribution for the critical water impact parameters was used to determine the failure probability of each solid rocket booster component as functions of impact velocity and component strength capability.

Nanostructure Formation by controlled dewetting on patterned substrates: A combined theoretical, modeling and experimental study

PubMed Central

Lu, Liang-Xing; Wang, Ying-Min; Srinivasan, Bharathi Madurai; Asbahi, Mohamed; Yang, Joel K. W.; Zhang, Yong-Wei

2016-01-01

We perform systematic two-dimensional energetic analysis to study the stability of various nanostructures formed by dewetting solid films deposited on patterned substrates. Our analytical results show that by controlling system parameters such as the substrate surface pattern, film thickness and wetting angle, a variety of equilibrium nanostructures can be obtained. Phase diagrams are presented to show the complex relations between these system parameters and various nanostructure morphologies. We further carry out both phase field simulations and dewetting experiments to validate the analytically derived phase diagrams. Good agreements between the results from our energetic analyses and those from our phase field simulations and experiments verify our analysis. Hence, the phase diagrams presented here provide guidelines for using solid-state dewetting as a tool to achieve various nanostructures. PMID:27580943

Metastable Phase Evolution in Oxide Systems

NASA Astrophysics Data System (ADS)

Levi, Carlos G.

2005-03-01

Multi-component ceramics are often synthesized by routes that facilitate mixing at the molecular scale and subsequently generate a solid product at low homologous temperatures. Examples include chemical and physical vapor deposition, thermal spray, and pyrolytic decomposition of precursor solutions. In these processes the solid evolves rapidly from a highly energized state, typically in a temperature regime wherein long-range diffusion is largely constrained and the equilibrium configuration can be kinetically suppressed. The resulting product may exhibit various forms of metastability such as amorphization, nanocrystallinity, extended solid solubility and alternate crystalline forms. The approach allows access to novel combinations of structure and composition with unprecedented defect structures that, if reasonably durable, could have properties of potential technological interest. Understanding phase selection and evolution is facilitated by having a suitable reference framework depicting the thermodynamic hierarchy of the phases available to the system under the relevant processing conditions. When transformations are partitionless the phase menu and hierarchy can be readily derived from the relative position of the T0 curves/surfaces for the different pairs of phases. The result is a phase hierarchy map, which is an analog of the phase diagram for partitionless equilibrium. Such maps can then be used to assess the kinetic effects on the selection of metastable states and their subsequent evolution. This presentation will discuss the evolution of metastable phases in oxides, with emphasis on systems involving fluorite phases and their ordered or distorted derivatives. The concepts will be illustrated primarily with zirconia-based systems, notably those of interest in thermal barrier coatings, fuel cells and ferroelectrics (ZrO2-MO3/2, where M = Y, Sc, the lanthanides and combinations thereof, as well as ZrO2-YO3/2-TiO2, ZrO2-TiO2-PbO, etc.). Of particular interest are the durabilities of metastable phases in systems that operate at high temperature, their decomposition paths and the implications to their functionality.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

Solid-State NMR Investigation of Drug-Excipient Interactions and Phase Behavior in Indomethacin-Eudragit E Amorphous Solid Dispersions.

PubMed

Lubach, Joseph W; Hau, Jonathan

2018-02-20

To investigate the nature of drug-excipient interactions between indomethacin (IMC) and methacrylate copolymer Eudragit® E (EE) in the amorphous state, and evaluate the effects on formulation and stability of these amorphous systems. Amorphous solid dispersions containing IMC and EE were spray dried with drug loadings from 20% to 90%. PXRD was used to confirm the amorphous nature of the dispersions, and DSC was used to measure glass transition temperatures (T g ). 13 C and 15 N solid-state NMR was utilized to investigate changes in local structure and protonation state, while 1 H T 1 and T 1ρ relaxation measurements were used to probe miscibility and phase behavior of the dispersions. T g values for IMC-EE solid dispersions showed significant positive deviations from predicted values in the drug loading range of 40-90%, indicating a relatively strong drug-excipient interaction. 15 N solid-state NMR exhibited a change in protonation state of the EE basic amine, with two distinct populations for the EE amine at -360.7 ppm (unprotonated) and -344.4 ppm (protonated). Additionally, 1 H relaxation measurements showed phase separation at high drug load, indicating an amorphous ionic complex and free IMC-rich phase. PXRD data showed all ASDs up to 90% drug load remained physically stable after 2 years. 15 N solid-state NMR experiments show a change in protonation state of EE, indicating that an ionic complex indeed forms between IMC and EE in amorphous solid dispersions. Phase behavior was determined to exhibit nanoscale phase separation at high drug load between the amorphous ionic complex and excess free IMC.

Separation of gas from liquid in a two-phase flow system

NASA Technical Reports Server (NTRS)

Hayes, L. G.; Elliott, D. G.

1973-01-01

Separation system causes jets which leave two-phase nozzles to impinge on each other, so that liquid from jets tends to coalesce in center of combined jet streams while gas phase is forced to outer periphery. Thus, because liquid coalescence is achieved without resort to separation with solid surfaces, cycle efficiency is improved.

Structural ordering at solid-liquid interfaces in Al-Sm system: A molecular-dynamics study

DOE PAGES

Sun, Yang; Zhang, Feng; Ye, Zhuo; ...

2016-07-12

The structural ordering at solid-liquid interfaces far from equilibrium is studied with molecular dynamics simulations for the Al-Sm system. Using the van-Hove self-correlation function as the criterion to identify attachment/detachment events that occur at the interface, we are able to determine the time-dependent interface position, and characterize the detailed interfacial structure ordering surrounding the attached atoms. For the interface between an undercooled Al90Sm10 liquid and a metastable cubic structure, the solid induces the crystalline order of the cubic phase in the liquid layers, promoting the continuous growth of the crystal phase. When the same liquid is put in contact withmore » f.c.c. Al, Sm from the liquid can still attach to the solid interface despite its insolubility in the Al lattice. Non-f.c.c. order is revealed surrounding the attached Sm atoms. Lastly, we show that the local structure ordering at interface is highly correlated to solid packing and liquid ordering.« less

Three-Phase Melting Curves in the Binary System of Carbon Dioxide and Water

NASA Astrophysics Data System (ADS)

Abramson, E. H.

2017-10-01

Invariant, three-phase melting curves, of ice VI in equilibrium with solid CO2, of ice VII in equilibrium with solid CO2, and of solid CO2 in simultaneous equilibrium with a majority aqueous and a majority CO2 fluid, were explored in the binary system of carbon dioxide and water. Diamond-anvil cells were used to develop pressures of 5 GPa. Water exhibits a large melting temperature depression (73°C less than its pure melting temperature of 253°C at 5 GPa) indicative of large concentrations of CO2 in the aqueous solution. The melting point of water-saturated CO2 does not show a measureable departure from that of the pure system at temperatures lower than ∼200°C and only 10°C at 5 GPa (from 327°C).

Fluid flow in solidifying monotectic alloys

NASA Technical Reports Server (NTRS)

Ecker, A.; Frazier, D. O.; Alexander, J. Iwan D.

1989-01-01

Use of a two-wavelength holographic technique results in a simultaneous determination of temperature and composition profiles during directional solidification in a system with a miscibility gap. The relationships among fluid flow, phase separation, and mass transport during the solidification of the monotectic alloy are discussed. The primary sources of fluid motion in this system are buoyancy and thermocapillary forces. These forces act together when phase separation results in the formation of droplets (this occurs at the solid-liquid interface and in the bulk melt). In the absence of phase separation, buoyancy results from density gradients related to temperature and compositional gradients in the single-phase bulk melt. The effects of buoyancy are especially evident in association with water- or ethanol-rich volumes created at the solid-liquid growth interface.

Hydration products in sulfoaluminate cements: Evaluation of amorphous phases by XRD/solid-state NMR

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

Gastaldi, D., E-mail: dgastaldi@buzziunicem.it; Paul, G., E-mail: geo.paul@uniupo.it; Marchese, L.

The hydration of four sulfoaluminate cements have been studied: three sulfoaluminate systems, having different content of sulfate and silicate, and one blend Portland-CSA-calcium sulfate binder. Hydration was followed up to 90 days by means of a combination of X-ray diffraction and solid state MAS-NMR; Differential scanning calorimetry and Scanning electron microscopy were also performed in order to help the interpretation of experimental data. High amount of amorphous phases were found in all the four systems: in low-sulfate cements, amorphous part is mainly ascribed to monosulfate and aluminium hydroxide, while strätlingite is observed if belite is present in the cement; inmore » the blend system, C-S-H contributes to the amorphous phase beyond monosulfate.« less

New Approaches in Soil Organic Matter Fluorescence; A Solid Phase Fluorescence Approach

NASA Astrophysics Data System (ADS)

Bowman, M. M.; Sanclements, M.; McKnight, D. M.

2017-12-01

Fluorescence spectroscopy is a well-established technique to investigate the composition of organic matter in aquatic systems and is increasingly applied to soil organic matter (SOM). Current methods require that SOM be extracted into a liquid prior to analysis by fluorescence spectroscopy. Soil extractions introduce an additional layer of complexity as the composition of the organic matter dissolved into solution varies based upon the selected extractant. Water is one of the most commonly used extractant, but only extracts the water-soluble fraction of the SOM with the insoluble soil organic matter fluorescence remaining in the soil matrix. We propose the use of solid phase fluorescence on whole soils as a potential tool to look at the composition of organic matter without the extraction bias and gain a more complete understand of the potential for fluorescence as a tool in terrestrial studies. To date, the limited applications of solid phase fluorescence have ranged from food and agriculture to pharmaceutical with no clearly defined methods and limitations available. We are aware of no other studies that use solid phase fluorescence and thus no clear methods to look at SOM across a diverse set of soil types and ecosystems. With this new approach to fluorescence spectroscopy there are new challenges, such as blank correction, inner filter effect corrections, and sample preparation. This work outlines a novel method for analyzing soil organic matter using solid phase fluorescence across a wide range of soils collected from the National Ecological Observatory Network (NEON) eco-domains. This method has shown that organic matter content in soils must be diluted to 2% to reduce backscattering and oversaturation of the detector in forested soils. In mineral horizons (A) there is observed quenching of the humic-like organic matter, which is likely a result of organo-mineral complexation. Finally, we present preliminary comparisons between solid and liquid phase fluorescence, which provide new insights into fluorescence studies in terrestrial systems.

Instrumental Analysis in Environmental Chemistry - Liquid and Solid Phase Detection Systems

ERIC Educational Resources Information Center

Stedman, Donald H.; Meyers, Philip A.

1974-01-01

This is the second of two reviews dealing with analytical methods applicable to environmental chemistry. Methods are discussed under gas, liquid, or solid depending upon the state of the analyte during detection. (RH)

Metastable State during Melting and Solid-Solid Phase Transition of [CnMim][NO3] (n = 4-12) Ionic Liquids by Molecular Dynamics Simulation.

PubMed

Cao, Wudi; Wang, Yanting; Saielli, Giacomo

2018-01-11

We simulate the heating process of ionic liquids [C n Mim][NO 3 ] (n = 4, 6, 8, 10, 12), abbreviated as C n , by means of molecular dynamics (MD) simulation starting from a manually constructed triclinic crystal structure composed of polar layers containing anions and cationic head groups and nonpolar regions in between containing cationic alkyl side chains. During the heating process starting from 200 K, each system undergoes first a solid-solid phase transition at a lower temperature, and then a melting phase transition at a higher temperature to an isotropic liquid state (C 4 , C 6 , and C 8 ) or to a liquid crystal state (C 10 and C 12 ). After the solid-solid phase transition, all systems keep the triclinic space symmetry, but have a different set of lattice constants. C 4 has a more significant structural change in the nonpolar regions which narrows the layer spacing, while the layer spacings of other systems change little, which can be qualitatively understood by considering that the contribution of the effective van der Waals interaction in the nonpolar regions (abbreviated as EF1) to free energy becomes stronger with increasing side-chain length, and at the same time the contribution of the effective electrostatic interaction in the polar layers (abbreviated as EF2) to free energy remains almost the same. The melting phase transitions of all systems except C 6 are found to be a two-step process with an intermediate metastable state appeared during the melting from the crystal state to the liquid or liquid crystal state. Because the contribution of EF2 to the free energy is larger than EF1, the metastable state of C 4 has the feature of having higher ordered polar layers and lower ordered side-chain orientation. By contrast, C 8 -C 12 have the feature of having lower ordered polar layers and higher ordered side-chain orientation, because for these systems, the contribution of EF2 to the free energy is smaller than EF1. No metastable state is found for C 6 because the free-energy contribution of EF1 is balanced with EF2.

Ab Initio Simulation Beryllium in Solid Molecular Hydrogen: Elastic Constant

NASA Astrophysics Data System (ADS)

Guerrero, Carlo L.; Perlado, Jose M.

2016-03-01

In systems of inertial confinement fusion targets Deuterium-Tritium are manufactured with a solid layer, it must have specific properties to increase the efficiency of ignition. Currently there have been some proposals to model the phases of hydrogen isotopes and hence their high pressure, but these works do not allow explaining some of the structures present at the solid phase change effect of increased pressure. By means of simulation with first principles methods and Quantum Molecular Dynamics, we compare the structural difference of solid molecular hydrogen pure and solid molecular hydrogen with beryllium, watching beryllium inclusion in solid hydrogen matrix, we obtain several differences in mechanical properties, in particular elastic constants. For C11 the difference between hydrogen and hydrogen with beryllium is 37.56%. This may produce a non-uniform initial compression and decreased efficiency of ignition.

Phase Transitions in Model Active Systems

NASA Astrophysics Data System (ADS)

Redner, Gabriel S.

The amazing collective behaviors of active systems such as bird flocks, schools of fish, and colonies of microorganisms have long amazed scientists and laypeople alike. Understanding the physics of such systems is challenging due to their far-from-equilibrium dynamics, as well as the extreme diversity in their ingredients, relevant time- and length-scales, and emergent phenomenology. To make progress, one can categorize active systems by the symmetries of their constituent particles, as well as how activity is expressed. In this work, we examine two categories of active systems, and explore their phase behavior in detail. First, we study systems of self-propelled spherical particles moving in two dimensions. Despite the absence of an aligning interaction, this system displays complex emergent dynamics, including phase separation into a dense active solid and dilute gas. Using simulations and analytic modeling, we quantify the phase diagram and separation kinetics. We show that this nonequilibrium phase transition is analogous to an equilibrium vapor-liquid system, with binodal and spinodal curves and a critical point. We also characterize the dense active solid phase, a unique material which exhibits the structural signatures of a crystalline solid near the crystal-hexatic transition point, as well as anomalous dynamics including superdiffusive motion on intermediate timescales. We also explore the role of interparticle attraction in this system. We demonstrate that attraction drastically changes the phase diagram, which contains two distinct phase-separated regions and is reentrant as a function of propulsion speed. We interpret this complex situation with a simple kinetic model, which builds from the observed microdynamics of individual particles to a full description of the macroscopic phase behavior. We also study active nematics, liquid crystals driven out of equilibrium by energy-dissipating active stresses. The equilibrium nematic state is unstable in these materials, leading to beautiful and surprising behaviors including the spontaneous generation of topological defect pairs which stream through the system and later annihilate, yielding a complex, seemingly chaotic dynamical steady-state. Here, we describe the emergence of order from this chaos in the form of previously unknown broken-symmetry phases in which the topological defects themselves undergo orientational ordering. We have identified these defect-ordered phases in two realizations of an active nematic: first, a suspension of extensile bundles of microtubules and molecular motor proteins, and second, a computational model of extending hard rods. We will describe the defect-stabilized phases that manifest in these systems, our current understanding of their origins, and discuss whether such phases may be a general feature of extensile active nematics.

Chemical Separation of Fe-Ni Particles after Impact

NASA Astrophysics Data System (ADS)

Miura, Y.; Fukuyama, S.; Kedves, M. A.; Yamori, A.; Okamoto, M.; Gucsik, A.

Tiny grains of Fe-Ni system originated from planetesimals or meteoroids can remain under solid (or melt)-solid impact reactions even after impact process, probably together with high pressure form of Fe phase. Impact fragment with major Fe-Si (-Ni) system can be formed under vapor condition of impact reaction from terrestrial and artificial impact craters and spherules, and those with Ni-Cl (-S) system in composi- tion are formed under vapor condition of artificial impact experiments on the Barringer iron meteorite. These impact grains of Fe-bearing composition or high pressure form of iron-rich phases will be found probably on the asteroids in future exploration

A Simple Approach to Characterize Gas-Aqueous Liquid Two-phase Flow Configuration Based on Discrete Solid-Liquid Contact Electrification

PubMed Central

Choi, Dongwhi; Lee, Donghyeon; Sung Kim, Dong

2015-01-01

In this study, we first suggest a simple approach to characterize configuration of gas-aqueous liquid two–phase flow based on discrete solid-liquid contact electrification, which is a newly defined concept as a sequential process of solid-liquid contact and successive detachment of the contact liquid from the solid surface. This approach exhibits several advantages such as simple operation, precise measurement, and cost-effectiveness. By using electric potential that is spontaneously generated by discrete solid–liquid contact electrification, the configurations of the gas-aqueous liquid two-phase flow such as size of a gas slug and flow rate are precisely characterized. According to the experimental and numerical analyses on parameters that affect electric potential, gas slugs have been verified to behave similarly to point electric charges when the measuring point of the electric potential is far enough from the gas slug. In addition, the configuration of the gas-aqueous liquid two-phase microfluidic system with multiple gas slugs is also characterized by using the presented approach. For a proof-of-concept demonstration of using the proposed approach in a self-triggered sensor, a gas slug detector with a counter system is developed to show its practicality and applicability. PMID:26462437

Phase diagram and high-pressure boundary of hydrate formation in the ethane-water system.

PubMed

Kurnosov, Alexander V; Ogienko, Andrey G; Goryainov, Sergei V; Larionov, Eduard G; Manakov, Andrey Y; Lihacheva, Anna Y; Aladko, Eugeny Y; Zhurko, Fridrikh V; Voronin, Vladimir I; Berger, Ivan F; Ancharov, Aleksei I

2006-11-02

Dissociation temperatures of gas hydrate formed in the ethane-water system were studied at pressures up to 1500 MPa. In situ neutron diffraction analysis and X-ray diffraction analysis in a diamond anvil cell showed that the gas hydrate formed in the ethane-water system at 340, 700, and 1840 MPa and room temperature belongs to the cubic structure I (CS-I). Raman spectra of C-C vibrations of ethane molecules in the hydrate phase, as well as the spectra of solid and liquid ethane under high-pressure conditions were studied at pressures up to 6900 MPa. Within 170-3600 MPa Raman shift of the C-C vibration mode of ethane in the hydrate phase did not show any discontinuities, which could be evidence of possible phase transformations. The upper pressure boundary of high-pressure hydrate existence was discovered at the pressure of 3600 MPa. This boundary corresponds to decomposition of the hydrate to solid ethane and ice VII. The type of phase diagram of ethane-water system was proposed in the pressure range of hydrate formation (0-3600 MPa).

High-rate anaerobic treatment system for solid/lipid-rich wastewater using anaerobic baffled reactor with scum recovery.

PubMed

Fujihira, Takuya; Seo, Shogo; Yamaguchi, Takashi; Hatamoto, Masashi; Tanikawa, Daisuke

2018-04-27

A laboratory scale experiment was conducted to investigate the treatment of solid/lipid-rich wastewater with an anaerobic baffled reactor (ABR) and a down-flow hanging sponge (DHS) reactor. In this study, experimental periods were divided into three phases to explore efficient treatment of solids and lipids in wastewater. In ABR, >90% of the influent chemical oxygen demand (COD) was removed and >70% of the removed COD was converted to methane under steady-state conditions during each phase. During this period, >4.5 kg COD m -3  d -1 was achieved on an average in Phases 1 and 3. Biogas contributed to scum formation, and the scum was categorized into lipid-rich and sludge-containing types, which have energy potentials of 53.4 and 212 kcal/kg-wet weight, respectively. Therefore, by recovering solids and lipids, which formed persistent scum, ABR can be applied as a high-rate treatment for solid/lipid-rich wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Transient Numerical Modeling of Catalytic Channels

NASA Technical Reports Server (NTRS)

Struk, Peter M.; Dietrich, Daniel L.; Miller, Fletcher J.; T'ien, James S.

2007-01-01

This paper presents a transient model of catalytic combustion suitable for isolated channels and monolith reactors. The model is a lumped two-phase (gas and solid) model where the gas phase is quasi-steady relative to the transient solid. Axial diffusion is neglected in the gas phase; lateral diffusion, however, is accounted for using transfer coefficients. The solid phase includes axial heat conduction and external heat loss due to convection and radiation. The combustion process utilizes detailed gas and surface reaction models. The gas-phase model becomes a system of stiff ordinary differential equations while the solid phase reduces, after discretization, into a system of stiff ordinary differential-algebraic equations. The time evolution of the system came from alternating integrations of the quasi-steady gas and transient solid. This work outlines the numerical model and presents some sensitivity studies on important parameters including internal transfer coefficients, catalytic surface site density, and external heat-loss (if applicable). The model is compared to two experiments using CO fuel: (1) steady-state conversion through an isothermal platinum (Pt) tube and (2) transient propagation of a catalytic reaction inside a small Pt tube. The model requires internal mass-transfer resistance to match the experiments at lower residence times. Under mass-transport limited conditions, the model reasonably predicted exit conversion using global mass-transfer coefficients. Near light-off, the model results did not match the experiment precisely even after adjustment of mass-transfer coefficients. Agreement improved for the first case after adjusting the surface kinetics such that the net rate of CO adsorption increased compared to O2. The CO / O2 surface mechanism came from a sub-set of reactions in a popular CH4 / O2 mechanism. For the second case, predictions improved for lean conditions with increased external heat loss or adjustment of the kinetics as in the first case. Finally, the results show that different initial surface-species distribution leads to different steady-states under certain conditions. These results demonstrate the utility of a lumped two-phase model of a transient catalytic combustor with detailed chemistry.

Equations of state for the fully flexible WCA chains in the fluid and solid phases based on Wertheims-TPT2

NASA Astrophysics Data System (ADS)

Mirzaeinia, Ali; Feyzi, Farzaneh; Hashemianzadeh, Seyed Majid

2018-03-01

Based on Wertheim's second order thermodynamic perturbation theory (TPT2), equations of state (EOSs) are presented for the fluid and solid phases of tangent, freely jointed spheres. It is considered that the spheres interact with each other through the Weeks-Chandler-Anderson (WCA) potential. The developed TPT2 EOS is the sum of a monomeric reference term and a perturbation contribution due to bonding. MC NVT simulations are performed to determine the structural properties of the reference system in the reduced temperature range of 0.6 ≤ T* ≤ 4.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. Mathematical functions are fitted to the simulation results of the reference system and employed in the framework of Wertheim's theory to develop TPT2 EOSs for the fluid and solid phases. The extended EOSs are compared to the MC NPT simulation results of the compressibility factor and internal energy of the fully flexible chain systems. Simulations are performed for the WCA chain system for chain lengths of up to 15 at T* = 1.0, 1.5, 2.0, 3.0. Across all the reduced temperatures, the agreement between the results of the TPT2 EOS and MC simulations is remarkable. Overall Average Absolute Relative Percent Deviation at T* = 1.0 for the compressibility factor in the entire chain lengths we covered is 0.51 and 0.77 for the solid and fluid phases, respectively. Similar features are observed in the case of residual internal energy.

Equations of state for the fully flexible WCA chains in the fluid and solid phases based on Wertheims-TPT2.

PubMed

Mirzaeinia, Ali; Feyzi, Farzaneh; Hashemianzadeh, Seyed Majid

2018-03-14

Based on Wertheim's second order thermodynamic perturbation theory (TPT2), equations of state (EOSs) are presented for the fluid and solid phases of tangent, freely jointed spheres. It is considered that the spheres interact with each other through the Weeks-Chandler-Anderson (WCA) potential. The developed TPT2 EOS is the sum of a monomeric reference term and a perturbation contribution due to bonding. MC NVT simulations are performed to determine the structural properties of the reference system in the reduced temperature range of 0.6 ≤ T* ≤ 4.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. Mathematical functions are fitted to the simulation results of the reference system and employed in the framework of Wertheim's theory to develop TPT2 EOSs for the fluid and solid phases. The extended EOSs are compared to the MC NPT simulation results of the compressibility factor and internal energy of the fully flexible chain systems. Simulations are performed for the WCA chain system for chain lengths of up to 15 at T* = 1.0, 1.5, 2.0, 3.0. Across all the reduced temperatures, the agreement between the results of the TPT2 EOS and MC simulations is remarkable. Overall Average Absolute Relative Percent Deviation at T* = 1.0 for the compressibility factor in the entire chain lengths we covered is 0.51 and 0.77 for the solid and fluid phases, respectively. Similar features are observed in the case of residual internal energy.

Solid state SPS microwave generation and transmission study. Volume 2, phase 2: Appendices

NASA Technical Reports Server (NTRS)

Maynard, O. E.

1980-01-01

The solid state sandwich concept for SPS was further defined. The design effort concentrated on the spacetenna, but did include some system analysis for parametric comparison reasons. Basic solid state microwave devices were defined and modeled. An initial conceptual subsystems and system design was performed as well as sidelobe control and system selection. The selected system concept and parametric solid state microwave power transmission system data were assessed relevant to the SPS concept. Although device efficiency was not a goal, the sensitivities to design of this efficiency were parametrically treated. Sidelobe control consisted of various single step tapers, multistep tapers and Gaussian tapers. A hybrid concept using tubes and solid state was evaluated. Thermal analyses are included with emphasis on sensitivities to waste heat radiator form factor, emissivity, absorptivity, amplifier efficiency, material and junction temperature.

Reversed phase HPLC analysis of stability and microstructural effects on degradation kinetics of β-carotene encapsulated in freeze-dried maltodextrin-emulsion systems.

PubMed

Harnkarnsujarit, Nathdanai; Charoenrein, Sanguansri; Roos, Yrjö H

2012-09-26

Degradation of dispersed lipophilic compounds in hydrophilic solids depends upon matrix stability and lipid physicochemical properties. This study investigated effects of solid microstructure and size of lipid droplets on the stability of dispersed β-carotene in freeze-dried systems. Emulsions of β-carotene in sunflower oil were dispersed in maltodextrin systems (M040/DE6, M100/DE11, and M250/DE25.5) (8% w/w oil) and prefrozen at various freezing conditions prior to freeze-drying to control nucleation and subsequent pore size and structural collapse of freeze-dried solids. The particle size, physical state, and β-carotene contents of freeze-dried emulsions were measured during storage at various water activity (a(w)) using a laser particle size analyzer, differential scanning calorimeter, and high performance liquid chromatography (HPLC), respectively. The results showed that M040 stabilized emulsions in low temperature freezing exhibited lipid crystallization. Collapse of solids in storage at a(w) which plasticized systems to the rubbery state led to flow and increased the size of oil droplets. Degradation of β-carotene analyzed using a reversed-phase C(30) column followed first-order kinetics. Porosity of solids had a major effect on β-carotene stability; however, the highest stability was found in fully plasticized and collapsed solids.

Solid Hydrogen Experiments for Atomic Propellants: Particle Formation Energy and Imaging Analyses

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2002-01-01

This paper presents particle formation energy balances and detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium during the Phase II testing in 2001. Solid particles of hydrogen were frozen in liquid helium and observed with a video camera. The solid hydrogen particle sizes and the total mass of hydrogen particles were estimated. The particle formation efficiency is also estimated. Particle sizes from the Phase I testing in 1999 and the Phase II testing in 2001 were similar. Though the 2001 testing created similar particles sizes, many new particle formation phenomena were observed. These experiment image analyses are one of the first steps toward visually characterizing these particles and it allows designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.

All solid-state SBS phase conjugate mirror

DOEpatents

Dane, Clifford B.; Hackel, Lloyd A.

1999-01-01

A stimulated Brillouin scattering (SBS) phase conjugate laser mirror uses a solid-state nonlinear gain medium instead of the conventional liquid or high pressure gas medium. The concept has been effectively demonstrated using common optical-grade fused silica. An energy threshold of 2.5 mJ and a slope efficiency of over 90% were achieved, resulting in an overall energy reflectivity of >80% for 15 ns, 1 um laser pulses. The use of solid-state materials is enabled by a multi-pass resonant architecture which suppresses transient fluctuations that would otherwise result in damage to the SBS medium. This all solid state phase conjugator is safer, more reliable, and more easily manufactured than prior art designs. It allows nonlinear wavefront correction to be implemented in industrial and defense laser systems whose operating environments would preclude the introduction of potentially hazardous liquids or high pressure gases.

All solid-state SBS phase conjugate mirror

DOEpatents

Dane, C.B.; Hackel, L.A.

1999-03-09

A stimulated Brillouin scattering (SBS) phase conjugate laser mirror uses a solid-state nonlinear gain medium instead of the conventional liquid or high pressure gas medium. The concept has been effectively demonstrated using common optical-grade fused silica. An energy threshold of 2.5 mJ and a slope efficiency of over 90% were achieved, resulting in an overall energy reflectivity of >80% for 15 ns, 1 um laser pulses. The use of solid-state materials is enabled by a multi-pass resonant architecture which suppresses transient fluctuations that would otherwise result in damage to the SBS medium. This all solid state phase conjugator is safer, more reliable, and more easily manufactured than prior art designs. It allows nonlinear wavefront correction to be implemented in industrial and defense laser systems whose operating environments would preclude the introduction of potentially hazardous liquids or high pressure gases. 8 figs.

Micro versus macro solid phase extraction for monitoring water contaminants: a preliminary study using trihalomethanes.

PubMed

Alexandrou, Lydon D; Spencer, Michelle J S; Morrison, Paul D; Meehan, Barry J; Jones, Oliver A H

2015-04-15

Solid phase extraction is one of the most commonly used pre-concentration and cleanup steps in environmental science. However, traditional methods need electrically powered pumps, can use large volumes of solvent (if multiple samples are run), and require several hours to filter a sample. Additionally, if the cartridge is open to the air volatile compounds may be lost and sample integrity compromised. In contrast, micro cartridge based solid phase extraction can be completed in less than 2 min by hand, uses only microlitres of solvent and provides comparable concentration factors to established methods. It is also an enclosed system so volatile components are not lost. The sample can also be eluted directly into a detector (e.g. a mass spectrometer) if required. However, the technology is new and has not been much used for environmental analysis. In this study we compare traditional (macro) and the new micro solid phase extraction for the analysis of four common volatile trihalomethanes (trichloromethane, bromodichloromethane, dibromochloromethane and tribromomethane). The results demonstrate that micro solid phase extraction is faster and cheaper than traditional methods with similar recovery rates for the target compounds. This method shows potential for further development in a range of applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination

NASA Astrophysics Data System (ADS)

Mogolodi Dimpe, K.; Mpupa, Anele; Nomngongo, Philiswa N.

2018-01-01

This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5 μg L- 1 and 1.7 μg L- 1, respectively, and intraday and interday precision expressed in terms of relative standard deviation were > 6%.The maximum adsorption capacity was 138 mg g- 1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water.

Biogas production from municipal solid wastes using an integrated rotary drum and anaerobic-phased solids digester system.

PubMed

Zhu, Baoning; Zhang, Ruihong; Gikas, Petros; Rapport, Joshua; Jenkins, Bryan; Li, Xiujin

2010-08-01

This research was conducted to develop an integrated rotary drum reactor (RDR)-anaerobic-phased solids (APS) digester system for the treatment of municipal solid waste (MSW) to produce biogas energy and achieve waste reduction. A commercial RDR facility was used to provide a 3-d pretreatment and sufficient separation of the organics from MSW and then the organics were digested in a laboratory APS-digester system for biogas production. The organics generated from the RDR contained 50% total solids (TS) and 36% volatile solids (VS) on wet basis. The APS-digester was started at an organic loading rate (OLR) of 3.1 gVS L(-1) d(-1) and operated at three higher OLRs of 4.6, 7.7 and 9.2 gVS L(-1) d(-1). At the OLR of 9.2 gVS L(-1) d(-1) the system biogas production rate was 3.5 L L(-1) d(-1) and the biogas and methane yields were 0.38 and 0.19 L gVS(-1), respectively. Anaerobic digestion resulted in 38% TS reduction and 53% VS reduction in the organic solids. It was found that the total VFA concentration reached a peak value of 15,000 mg L(-1) as acetic acid in the first 3d of batch digestion and later decreased to about 500 mg L(-1). The APS-digester system remained stable at each OLRs for over 100d with the pH in the hydrolysis reactors in the range of 7.3-7.8 and the pH in the biogasification reactor in 7.9-8.1. The residual solids after the digestion had a high heating value of 14.7 kJ gTS(-1). Copyright 2010 Elsevier Ltd. All rights reserved.

Solid-phase fullerene-like nanostructures as singlet oxygen photosensitizers in liquid media

NASA Astrophysics Data System (ADS)

Belousova, I. M.; Danilov, O. B.; Kiselev, V. M.; Kislyakov, I. M.; Kris'ko, T. K.; Murav'eva, T. D.; Videnichev, D. A.

2007-04-01

Singlet oxygen generation by fullerene and astralen containing surfaces and powders under visible irradiation was studied in water and organic liquids by means of 1Δ g state luminescence and chemical scavenger transmittance measurements. The chemical method, pioneered for solid photosensitizers of 10 II, allowed to measure the singlet oxygen concentration in the aqueous medium down to 10 8 cm -3. The singlet oxygen sensitizing by the solid-phase fullerene-containing systems was found to be 100 times less effective then by fullerene in solution. The results obtained confirm the applicability of these structures in biology and medicine.

Revisiting low-fidelity two-fluid models for gas-solids transport

NASA Astrophysics Data System (ADS)

Adeleke, Najeem; Adewumi, Michael; Ityokumbul, Thaddeus

2016-08-01

Two-phase gas-solids transport models are widely utilized for process design and automation in a broad range of industrial applications. Some of these applications include proppant transport in gaseous fracking fluids, air/gas drilling hydraulics, coal-gasification reactors and food processing units. Systems automation and real time process optimization stand to benefit a great deal from availability of efficient and accurate theoretical models for operations data processing. However, modeling two-phase pneumatic transport systems accurately requires a comprehensive understanding of gas-solids flow behavior. In this study we discuss the prevailing flow conditions and present a low-fidelity two-fluid model equation for particulate transport. The model equations are formulated in a manner that ensures the physical flux term remains conservative despite the inclusion of solids normal stress through the empirical formula for modulus of elasticity. A new set of Roe-Pike averages are presented for the resulting strictly hyperbolic flux term in the system of equations, which was used to develop a Roe-type approximate Riemann solver. The resulting scheme is stable regardless of the choice of flux-limiter. The model is evaluated by the prediction of experimental results from both pneumatic riser and air-drilling hydraulics systems. We demonstrate the effect and impact of numerical formulation and choice of numerical scheme on model predictions. We illustrate the capability of a low-fidelity one-dimensional two-fluid model in predicting relevant flow parameters in two-phase particulate systems accurately even under flow regimes involving counter-current flow.

FOURTH ANNUAL REPORT ON DISTRIBUTION STUDIES BETWEEN MELTS AND SOLID PHASES USING RADIOACTIVE TRACERS

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

Ward, R.; Orr, W.C.; Katz, L.

Cerium(III) ion in a barium chloride flux does not readily exchangs with any of the ions in solid BaZrO/sub 3/ or BaTiO/sub 3/. It reacts to form new solid phases, which are identified, and does not enter the original crystal lattices at an appreciable rate. The strontium was found to exchange at a measurable rate with barium in BaTiO/sub 3/ and with the corresponding ions in alkaline-earth zirconates. Results of a series of equilibrium and rate measurements were interpreted to ahow that the exchange produces an additional solid phase, SrTiO/sub 3/, rather than the mixed phase, or solid solution, thatmore » ndght have been expected. The significance of this observation is discussed. The self-exchange of yttnium ions between a solid compound of yttrium and an alkali chloride flux in which yttrium chloride is dissolved appears in the systems studied to depend primaaily on the solubility of the solid. Exchange is rapid and complete in the case of yttrium oxychlonide, which is soluble to the extent of 0.6%, but is limited to the surface of yttrium chromium oxide, which has no measurable solubility in the flux. The introduction of yttrium ion vacancies in the lattice of yttrium chromium oxide has no detectable effect in promoting exchange. (For preceding period see NYO-3279.) (auth)« less

A porous flow approach to model thermal non-equilibrium applicable to melt migration

NASA Astrophysics Data System (ADS)

Schmeling, Harro; Marquart, Gabriele; Grebe, Michael

2018-01-01

We develop an approach for heat exchange between a fluid and a solid phase of a porous medium where the temperatures of the fluid and matrix are not in thermal equilibrium. The formulation considers moving of the fluid within a resting or deforming porous matrix in an Eulerian coordinate system. The approach can be applied, for example, to partially molten systems or to brine transport in porous rocks. We start from an existing theory for heat exchange where the energy conservation equations for the fluid and the solid phases are separated and coupled by a heat exchange term. This term is extended to account for the full history of heat exchange. It depends on the microscopic geometry of the fluid phase. For the case of solid containing hot, fluid-filled channels, we derive an expression based on a time-dependent Fourier approach for periodic half-waves. On the macroscopic scale, the temporal evolution of the heat exchange leads to a convolution integral along the flow path of the solid, which simplifies considerably in case of a resting matrix. The evolution of the temperature in both phases with time is derived by inserting the heat exchange term into the energy equations. We explore the effects of thermal non-equilibrium between fluid and solid by considering simple cases with sudden temperature differences between fluid and solid as initial or boundary conditions, and by varying the fluid velocity with respect to the resting porous solid. Our results agree well with an analytical solution for non-moving fluid and solid. The temperature difference between solid and fluid depends on the Peclet number based on the Darcy velocity. For Peclet numbers larger than 1, the temperature difference after one diffusion time reaches 5 per cent of \\tilde{T} or more (\\tilde{T} is a scaling temperature, e.g. the initial temperature difference). Thus, our results imply that thermal non-equilibrium can play an important role for melt migration through partially molten systems where melt focuses into melt channels near the transition to melt ascent by dykes. Our method is based on solving the convolution integration for the heat exchange over the full flow history, which is numerically expensive. We tested to replace the heat exchange term by an instantaneous, approximate term. We found considerable errors on the short timescale, but a good agreement on the long timescale if appropriate parameters for the approximate terms are used. We derived these parameters which may be implemented in fully dynamical two-phase flow formulations of melt migration in the Earth.

SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOLID OXIDE FUEL CELL

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

Steven Shaffer; Sean Kelly; Subhasish Mukerjee

2003-12-08

The objective of Phase I under this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with the option of piped-in water (Demonstration System A). Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burnmore » internal combustion engine. This technical progress report covers work performed by Delphi from January 1, 2003 to June 30, 2003, under Department of Energy Cooperative Agreement DE-FC-02NT41246. This report highlights technical results of the work performed under the following tasks: Task 1 System Design and Integration; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant (BOP) Components; Task 5 Manufacturing Development (Privately Funded); Task 6 System Fabrication; Task 7 System Testing; Task 8 Program Management; and Task 9 Stack Testing with Coal-Based Reformate.« less

Thermodynamics of concentrated solid solution alloys

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

Gao, Michael C.; Zhang, C.; Gao, P.

This study reviews the three main approaches for predicting the formation of concentrated solid solution alloys (CSSA) and for modeling their thermodynamic properties, in particular, utilizing the methodologies of empirical thermo-physical parameters, CALPHAD method, and first-principles calculations combined with hybrid Monte Carlo/Molecular Dynamics (MC/MD) simulations. In order to speed up CSSA development, a variety of empirical parameters based on Hume-Rothery rules have been developed. Herein, these parameters have been systematically and critically evaluated for their efficiency in predicting solid solution formation. The phase stability of representative CSSA systems is then illustrated from the perspectives of phase diagrams and nucleation drivingmore » force plots of the σ phase using CALPHAD method. The temperature-dependent total entropies of the FCC, BCC, HCP, and σ phases in equimolar compositions of various systems are presented next, followed by the thermodynamic properties of mixing of the BCC phase in Al-containing and Ti-containing refractory metal systems. First-principles calculations on model FCC, BCC and HCP CSSA reveal the presence of both positive and negative vibrational entropies of mixing, while the calculated electronic entropies of mixing are negligible. Temperature dependent configurational entropy is determined from the atomic structures obtained from MC/MD simulations. Current status and challenges in using these methodologies as they pertain to thermodynamic property analysis and CSSA design are discussed.« less

Thermodynamics of concentrated solid solution alloys

DOE PAGES

Gao, Michael C.; Zhang, C.; Gao, P.; ...

2017-10-12

This study reviews the three main approaches for predicting the formation of concentrated solid solution alloys (CSSA) and for modeling their thermodynamic properties, in particular, utilizing the methodologies of empirical thermo-physical parameters, CALPHAD method, and first-principles calculations combined with hybrid Monte Carlo/Molecular Dynamics (MC/MD) simulations. In order to speed up CSSA development, a variety of empirical parameters based on Hume-Rothery rules have been developed. Herein, these parameters have been systematically and critically evaluated for their efficiency in predicting solid solution formation. The phase stability of representative CSSA systems is then illustrated from the perspectives of phase diagrams and nucleation drivingmore » force plots of the σ phase using CALPHAD method. The temperature-dependent total entropies of the FCC, BCC, HCP, and σ phases in equimolar compositions of various systems are presented next, followed by the thermodynamic properties of mixing of the BCC phase in Al-containing and Ti-containing refractory metal systems. First-principles calculations on model FCC, BCC and HCP CSSA reveal the presence of both positive and negative vibrational entropies of mixing, while the calculated electronic entropies of mixing are negligible. Temperature dependent configurational entropy is determined from the atomic structures obtained from MC/MD simulations. Current status and challenges in using these methodologies as they pertain to thermodynamic property analysis and CSSA design are discussed.« less

A METHOD FOR AUTOMATED ANALYSIS OF 10 ML WATER SAMPLES CONTAINING ACIDIC, BASIC, AND NEUTRAL SEMIVOLATILE COMPOUNDS LISTED IN USEPA METHOD 8270 BY SOLID PHASE EXTRACTION COUPLED IN-LINE TO LARGE VOLUME INJECTION GAS CHROMATOGRAPHY/MASS SPECTROMETRY

EPA Science Inventory

Data is presented showing the progress made towards the development of a new automated system combining solid phase extraction (SPE) with gas chromatography/mass spectrometry for the single run analysis of water samples containing a broad range of acid, base and neutral compounds...

Coherent thermodynamic model for solid, liquid and gas phases of elements and simple compounds in wide ranges of pressure and temperature

NASA Astrophysics Data System (ADS)

Holzapfel, Wilfried B.

2018-06-01

Thermodynamic modeling of fluids (liquids and gases) uses mostly series expansions which diverge at low temperatures and do not fit to the behavior of metastable quenched fluids (amorphous, glass like solids). These divergences are removed in the present approach by the use of reasonable forms for the "cold" potential energy and for the thermal pressure of the fluid system. Both terms are related to the potential energy and to the thermal pressure of the crystalline phase in a coherent way, which leads to simpler and non diverging series expansions for the thermal pressure and thermal energy of the fluid system. Data for solid and fluid argon are used to illustrate the potential of the present approach.

Universal Features of the Fluid to Solid Transition for Attractive Colloidal Particles

NASA Technical Reports Server (NTRS)

Cipelletti, L.; Prasad, V.; Dinsmore, A.; Segre, P. N.; Weitz, D. A.; Trappe, V.

2002-01-01

Attractive colloidal particles can exhibit a fluid to solid phase transition if the magnitude of the attractive interaction is sufficiently large, if the volume fraction is sufficiently high, and if the applied stress is sufficiently small. The nature of this fluid to solid transition is similar for many different colloid systems, and for many different forms of interaction. The jamming phase transition captures the common features of these fluid to solid translations, by unifying the behavior as a function of the particle volume fraction, the energy of interparticle attractions, and the applied stress. This paper describes the applicability of the jamming state diagram, and highlights those regions where the fluid to solid transition is still poorly understood. It also presents new data for gelation of colloidal particles with an attractive depletion interaction, providing more insight into the origin of the fluid to solid transition.

Organic alloy systems suitable for the investigation of regular binary and ternary eutectic growth

NASA Astrophysics Data System (ADS)

Sturz, L.; Witusiewicz, V. T.; Hecht, U.; Rex, S.

2004-09-01

Transparent organic alloys showing a plastic crystal phase were investigated experimentally using differential scanning calorimetry and directional solidification with respect to find a suitable model system for regular ternary eutectic growth. The temperature, enthalpy and entropy of phase transitions have been determined for a number of pure substances. A distinction of substances with and without plastic crystal phases was made from their entropy of melting. Binary phase diagrams were determined for selected plastic crystal alloys with the aim to identify eutectic reactions. Examples for lamellar and rod-like eutectic solidification microstructures in binary systems are given. The system (D)Camphor-Neopentylglycol-Succinonitrile is identified as a system that exhibits, among others, univariant and a nonvariant eutectic reaction. The ternary eutectic alloy close to the nonvariant eutectic composition solidifies with a partially faceted solid-liquid interface. However, by adding a small amount of Amino-Methyl-Propanediol (AMPD), the temperature of the nonvariant eutectic reaction and of the solid state transformation from plastic to crystalline state are shifted such, that regular eutectic growth with three distinct nonfaceted phases is observed in univariant eutectic reaction for the first time. The ternary phase diagram and examples for eutectic microstructures in the ternary and the quaternary eutectic alloy are given.

Robotic solid phase extraction and high performance liquid chromatographic analysis of ranitidine in serum or plasma.

PubMed

Lloyd, T L; Perschy, T B; Gooding, A E; Tomlinson, J J

1992-01-01

A fully automated assay for the analysis of ranitidine in serum and plasma, with and without an internal standard, was validated. It utilizes robotic solid phase extraction with on-line high performance liquid chromatographic (HPLC) analysis. The ruggedness of the assay was demonstrated over a three-year period. A Zymark Py Technology II robotic system was used for serial processing from initial aspiration of samples from original collection containers, to final direct injection onto the on-line HPLC system. Automated serial processing with on-line analysis provided uniform sample history and increased productivity by freeing the chemist to analyse data and perform other tasks. The solid phase extraction efficiency was 94% throughout the assay range of 10-250 ng/mL. The coefficients of variation for within- and between-day quality control samples ranged from 1 to 6% and 1 to 5%, respectively. Mean accuracy for between-day standards and quality control results ranged from 97 to 102% of the respective theoretical concentrations.

Phase and structural behavior of SmAlO{sub 3}–RAlO{sub 3} (R = Eu, Gd) systems

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

Ohon, N.; Vasylechko, L., E-mail: crystal-lov@polynet.lviv.ua; Prots, Yu.

2014-02-01

Highlights: • Continuous solid solutions exist in the SmAlO{sub 3}–RAlO{sub 3} (R = Eu, Gd) systems. • Lattice parameter crossover was found in solid solutions Sm{sub 1−x}R{sub x}AlO{sub 3} (R = Eu, Gd). • Thermally induced lattice crossovers occur in Sm{sub 0.9}R{sub 0.1}AlO{sub 3} at elevated temperatures. • First-order structural phase transition Pbnm↔R3{sup ¯}c was found in Sm{sub 1−x}R{sub x}AlO{sub 3} (R = Eu, Gd). • Phase diagram of the systems SmAlO{sub 3}–EuAlO{sub 3} and SmAlO{sub 3}–GdAlO{sub 3} has been constructed. - Abstract: Phase and structural behavior in the SmAlO{sub 3}–RAlO{sub 3} (R = Eu, Gd) systems has been studiedmore » in a whole concentration range by means of laboratory X-ray diffraction, in situ synchrotron powder diffraction and differential thermal analysis techniques. Continuous solid solutions with orthorhombic perovskite structure have been found in both systems. Peculiarity of the solid solutions of Sm{sub 1−x}Eu{sub x}AlO{sub 3} and Sm{sub 1−x}Gd{sub x}AlO{sub 3} is the existence of two lattice parameter crossovers in each system occurred at x{sub Eu} = 0.07 and 0.62 and at x{sub Gd} = 0.04 and 0.33, respectively. The temperature induced lattice crossovers in the Sm{sub 0.9}Eu{sub 0.1}AlO{sub 3} and Sm{sub 0.9}Gd{sub 0.1}AlO{sub 3} samples have been found at 387 and 922 K and at 501 and 894 K. First-order reversible structural phase transformations Pbnm↔R3{sup ¯}c have been detected in both systems at the elevated temperatures. The temperatures of these transitions increase linearly with the decreasing of the samarium content. Phase diagrams of the pseudo-binary systems SmAlO{sub 3}–EuAlO{sub 3} and SmAlO{sub 3}–GdAlO{sub 3} have been constructed.« less

Controlling Fundamentals in High-Energy High-Rate Pulsed Power Materials Processing of Powdered Tungsten, Titanium Aluminides, and Copper-Graphite Composites

DTIC Science & Technology

1990-10-01

phase systems such as tungsten; plastic flow of a minor low -temperature phase in a two phase non-interacting system such as tungsten- copper ; and...consolidation heat treatment. The de- the wetting of graphite by copper or during consolidation by this tech- tailed phase transformation evolution other...The driving potential for this solid state phase transformation is the free surface energy associated with the total powder particle surface area in the

Interdiffusion and Intrinsic Diffusion in the Mg-Al System

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

Brennan, Sarah; Bermudez, Katrina; Sohn, Yong Ho

2012-01-01

Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electronmore » microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the -Al3Mg2 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared to the available self- and impurity diffusion data from literature. Thermodynamic factor, tracer diffusion coefficients and atomic mobilities at the marker plane composition were approximated using available literature values of Mg activity in the -Al3Mg2 phase.« less

Influence of the Stefan Flow on Heat Transfer in the System "Gas-Solid Particle" in Thermochemical Conversion of a Solid Fuel

NASA Astrophysics Data System (ADS)

Pechenegov, Yu. Ya.; Mrakin, A. N.

2017-09-01

Recommendations are presented on calculating interphase heat transfer in gas-disperse systems of plants for thermochemical conversion of ground solid fuel. An analysis is made of the influence of the gas release of fuel particles on the heat transfer during their heating. It is shown that in the processes of thermal treatment of oil shales, the presence of gas release reduces substantially the intensity of interphase heat transfer compared to the heat transfer in the absence of thermochemical decomposition of the solid phase.

Equation of state and Helmholtz free energy for the atomic system of the repulsive Lennard-Jones particles.

PubMed

Mirzaeinia, Ali; Feyzi, Farzaneh; Hashemianzadeh, Seyed Majid

2017-12-07

Simple and accurate expressions are presented for the equation of state (EOS) and absolute Helmholtz free energy of a system composed of simple atomic particles interacting through the repulsive Lennard-Jones potential model in the fluid and solid phases. The introduced EOS has 17 and 22 coefficients for fluid and solid phases, respectively, which are regressed to the Monte Carlo (MC) simulation data over the reduced temperature range of 0.6≤T * ≤6.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. The average absolute relative percent deviation in fitting the EOS parameters to the MC data is 0.06 and 0.14 for the fluid and solid phases, respectively. The thermodynamic integration method is used to calculate the free energy using the MC simulation results. The Helmholtz free energy of the ideal gas is employed as the reference state for the fluid phase. For the solid phase, the values of the free energy at the reduced density equivalent to the close-packed of a hard sphere are used as the reference state. To check the validity of the predicted values of the Helmholtz free energy, the Widom particle insertion method and the Einstein crystal technique of Frenkel and Ladd are employed. The results obtained from the MC simulation approaches are well agreed to the EOS results, which show that the proposed model can reliably be utilized in the framework of thermodynamic theories.

Equation of state and Helmholtz free energy for the atomic system of the repulsive Lennard-Jones particles

NASA Astrophysics Data System (ADS)

Mirzaeinia, Ali; Feyzi, Farzaneh; Hashemianzadeh, Seyed Majid

2017-12-01

Simple and accurate expressions are presented for the equation of state (EOS) and absolute Helmholtz free energy of a system composed of simple atomic particles interacting through the repulsive Lennard-Jones potential model in the fluid and solid phases. The introduced EOS has 17 and 22 coefficients for fluid and solid phases, respectively, which are regressed to the Monte Carlo (MC) simulation data over the reduced temperature range of 0.6 ≤T*≤6.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. The average absolute relative percent deviation in fitting the EOS parameters to the MC data is 0.06 and 0.14 for the fluid and solid phases, respectively. The thermodynamic integration method is used to calculate the free energy using the MC simulation results. The Helmholtz free energy of the ideal gas is employed as the reference state for the fluid phase. For the solid phase, the values of the free energy at the reduced density equivalent to the close-packed of a hard sphere are used as the reference state. To check the validity of the predicted values of the Helmholtz free energy, the Widom particle insertion method and the Einstein crystal technique of Frenkel and Ladd are employed. The results obtained from the MC simulation approaches are well agreed to the EOS results, which show that the proposed model can reliably be utilized in the framework of thermodynamic theories.

Thermodynamic Model Formulations for Inhomogeneous Solids with Application to Non-isothermal Phase Field Modelling

NASA Astrophysics Data System (ADS)

Gladkov, Svyatoslav; Kochmann, Julian; Reese, Stefanie; Hütter, Markus; Svendsen, Bob

2016-04-01

The purpose of the current work is the comparison of thermodynamic model formulations for chemically and structurally inhomogeneous solids at finite deformation based on "standard" non-equilibrium thermodynamics [SNET: e. g. S. de Groot and P. Mazur, Non-equilibrium Thermodynamics, North Holland, 1962] and the general equation for non-equilibrium reversible-irreversible coupling (GENERIC) [H. C. Öttinger, Beyond Equilibrium Thermodynamics, Wiley Interscience, 2005]. In the process, non-isothermal generalizations of standard isothermal conservative [e. g. J. W. Cahn and J. E. Hilliard, Free energy of a non-uniform system. I. Interfacial energy. J. Chem. Phys. 28 (1958), 258-267] and non-conservative [e. g. S. M. Allen and J. W. Cahn, A macroscopic theory for antiphase boundary motion and its application to antiphase domain coarsening. Acta Metall. 27 (1979), 1085-1095; A. G. Khachaturyan, Theory of Structural Transformations in Solids, Wiley, New York, 1983] diffuse interface or "phase-field" models [e. g. P. C. Hohenberg and B. I. Halperin, Theory of dynamic critical phenomena, Rev. Modern Phys. 49 (1977), 435-479; N. Provatas and K. Elder, Phase Field Methods in Material Science and Engineering, Wiley-VCH, 2010.] for solids are obtained. The current treatment is consistent with, and includes, previous works [e. g. O. Penrose and P. C. Fife, Thermodynamically consistent models of phase-field type for the kinetics of phase transitions, Phys. D 43 (1990), 44-62; O. Penrose and P. C. Fife, On the relation between the standard phase-field model and a "thermodynamically consistent" phase-field model. Phys. D 69 (1993), 107-113] on non-isothermal systems as a special case. In the context of no-flux boundary conditions, the SNET- and GENERIC-based approaches are shown to be completely consistent with each other and result in equivalent temperature evolution relations.

Solid state SPS microwave generation and transmission study. Volume 1: Phase 2

NASA Technical Reports Server (NTRS)

Maynard, O. E.

1980-01-01

The solid state sandwich concept for Solar Power Station (SPS) was investigated. The design effort concentrated on the spacetenna, but did include some system analysis for parametric comparison reasons. The study specifically included definition and math modeling of basic solid state microwave devices, an initial conceptual subsystems and system design, sidelobe control and system selection, an assessment of selected system concept and parametric solid state microwave power transmission system data relevant to the SPS concept. Although device efficiency was not a goal, the sensitivities to design of this efficiency were parametrically treated. Sidelobe control consisted of various single step tapers, multistep tapers, and Gaussian tapers. A preliminary assessment of a hybrid concept using tubes and solid state is also included. There is a considerable amount of thermal analysis provided with emphasis on sensitivities to waste heat radiator form factor, emissivity, absorptivity, amplifier efficiency, material and junction temperature.

Solid polymer electrolyte water electrolysis system development. [to generate oxygen for manned space station applications

NASA Technical Reports Server (NTRS)

1975-01-01

Solid polymer electrolyte technology used in a water electrolysis system (WES) to generate oxygen and hydrogen for manned space station applications was investigated. A four-man rated, low pressure breadboard water electrolysis system with the necessary instrumentation and controls was fabricated and tested. A six man rated, high pressure, high temperature, advanced preprototype WES was developed. This configuration included the design and development of an advanced water electrolysis module, capable of operation at 400 psig and 200 F, and a dynamic phase separator/pump in place of a passive phase separator design. Evaluation of this system demonstrated the goal of safe, unattended automated operation at high pressure and high temperature with an accumulated gas generation time of over 1000 hours.

Construction of drug-polymer thermodynamic phase diagrams using Flory-Huggins interaction theory: identifying the relevance of temperature and drug weight fraction to phase separation within solid dispersions.

PubMed

Tian, Yiwei; Booth, Jonathan; Meehan, Elizabeth; Jones, David S; Li, Shu; Andrews, Gavin P

2013-01-07

Amorphous drug-polymer solid dispersions have the potential to enhance the dissolution performance and thus bioavailability of BCS class II drug compounds. The principle drawback of this approach is the limited physical stability of amorphous drug within the dispersion. Accurate determination of the solubility and miscibility of drug in the polymer matrix is the key to the successful design and development of such systems. In this paper, we propose a novel method, based on Flory-Huggins theory, to predict and compare the solubility and miscibility of drug in polymeric systems. The systems chosen for this study are (1) hydroxypropyl methylcellulose acetate succinate HF grade (HPMCAS-HF)-felodipine (FD) and (2) Soluplus (a graft copolymer of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol)-FD. Samples containing different drug compositions were mixed, ball milled, and then analyzed by differential scanning calorimetry (DSC). The value of the drug-polymer interaction parameter χ was calculated from the crystalline drug melting depression data and extrapolated to lower temperatures. The interaction parameter χ was also calculated at 25 °C for both systems using the van Krevelen solubility parameter method. The rank order of interaction parameters of the two systems obtained at this temperature was comparable. Diagrams of drug-polymer temperature-composition and free energy of mixing (ΔG(mix)) were constructed for both systems. The maximum crystalline drug solubility and amorphous drug miscibility may be predicted based on the phase diagrams. Hyper-DSC was used to assess the validity of constructed phase diagrams by annealing solid dispersions at specific drug loadings. Three different samples for each polymer were selected to represent different regions within the phase diagram.

Miscibility and Phase Behavior of N-Acylethanolamine/Diacylphosphatidylethanolamine Binary Mixtures of Matched Acyl Chainlengths (n = 14, 16)

PubMed Central

Kamlekar, Ravi Kanth; Satyanarayana, S.; Marsh, Derek; Swamy, Musti J.

2007-01-01

The miscibility and phase behavior of hydrated binary mixtures of two N-acylethanolamines (NAEs), N-myristoylethanolamine (NMEA), and N-palmitoylethanolamine (NPEA), with the corresponding diacyl phosphatidylethanolamines (PEs), dimyristoylphosphatidylethanolamine (DMPE), and dipalmitoylphosphatidylethanolamine (DPPE), respectively, have been investigated by differential scanning calorimetry (DSC), spin-label electron spin resonance (ESR), and 31P-NMR spectroscopy. Temperature-composition phase diagrams for both NMEA/DMPE and NPEA/DPPE binary systems were established from high sensitivity DSC. The structures of the phases involved were determined by 31P-NMR spectroscopy. For both systems, complete miscibility in the fluid and gel phases is indicated by DSC and ESR, up to 35 mol % of NMEA in DMPE and 40 mol % of NPEA in DPPE. At higher contents of the NAEs, extensive solid-fluid phase separation and solid-solid immiscibility occur depending on the temperature. Characterization of the structures of the mixtures formed with 31P-NMR spectroscopy shows that up to 75 mol % of NAE, both DMPE and DPPE form lamellar structures in the gel phase as well as up to at least 65°C in the fluid phase. ESR spectra of phosphatidylcholine spin labeled at the C-5 position in the sn-2 acyl chain present at a probe concentration of 1 mol % exhibit strong spin-spin broadening in the low-temperature region for both systems, suggesting that the acyl chains pack very tightly and exclude the spin label. However, spectra recorded in the fluid phase do not exhibit any spin-spin broadening and indicate complete miscibility of the two components. The miscibility of NAE and diacyl PE of matched chainlengths is significantly less than that found earlier for NPEA and dipalmitoylphosphatidylcholine, an observation that is consistent with the notion that the NAEs are most likely stored as their precursor lipids (N-acyl PEs) and are generated only when the system is subjected to membrane stress. PMID:17369415

Thermodynamic integration based on classical atomistic simulations to determine the Gibbs energy of condensed phases: Calculation of the aluminum-zirconium system

NASA Astrophysics Data System (ADS)

Harvey, J.-P.; Gheribi, A. E.; Chartrand, P.

2012-12-01

In this work, an in silico procedure to generate a fully coherent set of thermodynamic properties obtained from classical molecular dynamics (MD) and Monte Carlo (MC) simulations is proposed. The procedure is applied to the Al-Zr system because of its importance in the development of high strength Al-Li alloys and of bulk metallic glasses. Cohesive energies of the studied condensed phases of the Al-Zr system (the liquid phase, the fcc solid solution, and various orthorhombic stoichiometric compounds) are calculated using the modified embedded atom model (MEAM) in the second-nearest-neighbor formalism (2NN). The Al-Zr MEAM-2NN potential is parameterized in this work using ab initio and experimental data found in the literature for the AlZr3-L12 structure, while its predictive ability is confirmed for several other solid structures and for the liquid phase. The thermodynamic integration (TI) method is implemented in a general MC algorithm in order to evaluate the absolute Gibbs energy of the liquid and the fcc solutions. The entropy of mixing calculated from the TI method, combined to the enthalpy of mixing and the heat capacity data generated from MD/MC simulations performed in the isobaric-isothermal/canonical (NPT/NVT) ensembles are used to parameterize the Gibbs energy function of all the condensed phases in the Al-rich side of the Al-Zr system in a CALculation of PHAse Diagrams (CALPHAD) approach. The modified quasichemical model in the pair approximation (MQMPA) and the cluster variation method (CVM) in the tetrahedron approximation are used to define the Gibbs energy of the liquid and the fcc solid solution respectively for their entire range of composition. Thermodynamic and structural data generated from our MD/MC simulations are used as input data to parameterize these thermodynamic models. A detailed analysis of the validity and transferability of the Al-Zr MEAM-2NN potential is presented throughout our work by comparing the predicted properties obtained from this formalism with available ab initio and experimental data for both liquid and solid phases.

Radar Attitude Sensing System (RASS)

NASA Technical Reports Server (NTRS)

1971-01-01

The initial design and fabrication efforts for a radar attitude sensing system (RASS) are covered. The design and fabrication of the RASS system is being undertaken in two phases, 1B1 and 1B2. The RASS system as configured under phase 1B1 contains the solid state transmitter and local oscillator, the antenna system, the receiving system, and the altitude electronics. RASS employs a pseudo-random coded cw signal and receiver correlation techniques to measure range. The antenna is a planar, phased array, monopulse type, whose beam is electronically steerable using diode phase shifters. The beam steering computer and attitude sensing circuitry are to be included in Phase 1B2 of the program.

Spectral modification of seismic waves propagating through solids exhibiting a resonance frequency: a 1-D coupled wave propagation-oscillation model

NASA Astrophysics Data System (ADS)

Frehner, Marcel; Schmalholz, Stefan M.; Podladchikov, Yuri

2009-02-01

A 1-D model is presented that couples the microscale oscillations of non-wetting fluid blobs in a partially saturated poroelastic medium with the macroscale wave propagation through the elastic skeleton. The fluid oscillations are caused by surface tension forces that act as the restoring forces driving the oscillations. The oscillations are described mathematically with the equation for a linear oscillator and the wave propagation is described with the 1-D elastic wave equation. Coupling is done using Hamilton's variational principle for continuous systems. The resulting linear system of two partial differential equations is solved numerically with explicit finite differences. Numerical simulations are used to analyse the effect of solids exhibiting internal oscillations, and consequently a resonance frequency, on seismic waves propagating through such media. The phase velocity dispersion relation shows a higher phase velocity in the high-frequency limit and a lower phase velocity in the low-frequency limit. At the resonance frequency a singularity in the dispersion relation occurs. Seismic waves can initiate oscillations of the fluid by transferring energy from solid to fluid at the resonance frequency. Due to this transfer, the spectral amplitude of the solid particle velocity decreases at the resonance frequency. After initiation, the oscillatory movement of the fluid continuously transfers energy at the resonance frequency back to the solid. Therefore, the spectral amplitude of the solid particle velocity is increased at the resonance frequency. Once initiated, fluid oscillations decrease in amplitude with increasing time. Consequently, the spectral peak of the solid particle velocity at the resonance frequency decreases with time.

First application of supported ionic liquid phase (SILP) catalysis for continuous methanol carbonylation.

PubMed

Riisager, Anders; Jørgensen, Betina; Wasserscheid, Peter; Fehrmann, Rasmus

2006-03-07

A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)2I2]-[BMIM]I-SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation.

Thermal properties of spinel based solid solutions

NASA Astrophysics Data System (ADS)

O'Hara, Kelley Rae

Solid solution formation in spinel based systems proved to be a viable approach to decreasing thermal conductivity. Samples with systematically varied additions of MgGa2O4 to MgAl2O 4 were prepared and thermal diffusivity was measured using the laser flash technique. Additionally, heat capacity was measured using differential scanning calorimetry and modeled for the MgAl2O4-MgGa 2O4 system. At 200°C thermal conductivity decreased 24% with a 5 mol% addition of MgGa2O4 to the system. The solid solution continued to decrease the thermal conductivity by 13% up to 1000°C with 5 mol% addition. The decrease in thermal conductivity ultimately resulted in a decrease in heat flux when applied to a theoretical furnace lining, which could lead to energy savings in industrial settings. The MgAl2O4-Al2O3 phase equilibria was investigated to fully understand the system and the thermal properties at elevated temperatures. The solvus line between MgAl2O4 and Al2O3 has been defined at 79.6 wt% Al 2O3 at 1500°C, 83.0 wt% Al2O4 at 1600°C, and 86.5 wt% Al2O3 at 1700°C. A metastable region has been identified at temperatures up to 1700°C which could have significant implications for material processing and properties. The spinel solid solution region has been extended to form an infinite solid solution with Al2O3 at elevated temperatures. A minimum in melting at 1975°C and a chemistry of 96 wt% Al2O3 rather than a eutectic is present. Thermal properties in the MgAl2O4-Al2O 3 system were investigated in both the single phase solid solution region and the two phase region. The thermal diffusivity decreased through the MgAl 2O4 solid solution region and was at a minimum through the entire metastable (nucleation and growth) region. As Al2O 3 became present as a second phase the thermal diffusivity increased with Al2O3 content. There was an 11.7% increase in thermal diffusivity with a change in overall chemistry of 85.20 wt% Al2O 3 to 87.71 wt% Al2O3, due to the drastic change in final chemistry (38.3 wt% Al20 3) caused by the nucleation and growth region in the system.

Thermophysical Properties of Fluid Latent Heat Storage Material using Urea-Water Mixture

NASA Astrophysics Data System (ADS)

Hokamura, Taku; Ohkubo, Hidetoshi; Ashizawa, Kiyonori

This study is concerned with the measurement of thermophysical properties of a urea-water mixture with the aim of adopting the mixture as a latent heat storage material for air-conditioning systems. The urea-water mixture is made of natural substances and has a good fluidity. The urea concentration in the mixture was controlled by measuring the refractive index of the mixture. Being a multi-component substance, a urea-water solution has a liquid-solid co-existent phase on a phase-diagram. Therefore, the liquidus temperature was measured to establish a relationship between the fraction of the solid-phase and temperature. Furthermore, apparent values of specific heat and coefficient of viscosity were measured in the two-phase region where the solid phase is ice. The apparent specific heat and coefficient of viscosity were measure by using an adiabatic calorimeter and a stirring torque meter respectively. The results revealed that the urea-water mixture can probably be used as a latent heat storage material of good fluidity.

Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

NASA Astrophysics Data System (ADS)

Kistrup, Kasper; Skotte Sørensen, Karen; Wolff, Anders; Fougt Hansen, Mikkel

2015-04-01

We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/μg and 1.72(14) nL/μg were found for Milli-Q water and lysis-binding buffer, respectively.

Degradation of naproxen and carbamazepine in spiked sludge by slurry and solid-phase Trametes versicolor systems.

PubMed

Rodríguez-Rodríguez, Carlos E; Marco-Urrea, Ernest; Caminal, Gloria

2010-04-01

Growth and activity of the white-rot fungus Trametes versicolor on sewage sludge were assessed in bioslurry and solid-phase systems. Bioslurry cultures with different loads of sludge (10%, 25% and 38%, w/v) were performed. A lag phase of at least 2 d appeared in the 25 and 38%-cultures, however, the total fungal biomass was higher for the latter and lower for the 10%-culture after 30 d, as revealed by ergosterol determination. Detectable laccase activity levels were found in the 10 and 25%-cultures (up to 1308 and 2588 AUL(-1), respectively) while it was negligible in the 38%-culture. Important levels of ergosterol and laccase were obtained over a 60 d period in sludge solid-phase cultures amended with different concentrations of wheat straw pellets as lignocellulosic bulking material. Degradation experiments in 25%-bioslurry cultures spiked with naproxene (NAP, analgesic) and carbamazepine (CBZ, antiepileptic) showed depletion of around 47% and 57% within 24h, respectively. Complete depletion of NAP and around 48% for CBZ were achieved within 72 h in sludge solid cultures with 38% bulking material. CBZ degradation is especially remarkable due to its high persistence in wastewater treatment plants. Results showed that T. versicolor may be an interesting bioremediation agent for elimination of emerging pollutants in sewage sludge. Copyright 2009 Elsevier Ltd. All rights reserved.

On-line solid phase selective separation and preconcentration of Cd(II) by solid-phase extraction using carbon active modified with methyl thymol blue.

PubMed

Ensafi, Ali A; Ghaderi, Ali R

2007-09-05

An on-line flow system was used to develop a selective and efficient on-line sorbent extraction preconcentration system for cadmium. The method is based on adsorption of cadmium ions onto the activated carbon modified with methyl thymol blue. Then the adsorbed ions were washed using 0.5M HNO(3) and the eluent was used to determine the Cd(II) ions using flame atomic absorption spectrometry. The results obtained show that the modified activated carbon has the greatest adsorption capacity of 80 microg of Cd(II) per 1.0 g of the solid phase. The optimal pH value for the quantitative preconcentration was 9.0 and full desorption is achieved by using 0.5M HNO(3) solution. It is established that the solid phase can be used repeatedly without a considerable adsorption capacity loss. The detection limit was less than 1 ngmL(-1) Cd(II), with an enrichment factor of 1000. The calibration graph was linear in the range of 1-2000 ngmL(-1) Cd(II). The developed method has been applied to the determination of trace cadmium (II) in water samples and in the following reference materials: sewage sludge (CRM144R), and sea water (CASS.4) with satisfactory results. The accuracy was assessed through recovery experiments.

Computer simulation and high level virial theory of Saturn-ring or UFO colloids.

PubMed

Bates, Martin A; Dennison, Matthew; Masters, Andrew

2008-08-21

Monte Carlo simulations are used to map out the complete phase diagram of hard body UFO systems, in which the particles are composed of a concentric sphere and thin disk. The equation of state and phase behavior are determined for a range of relative sizes of the sphere and disk. We show that for relatively large disks, nematic and solid phases are observed in addition to the isotropic fluid. For small disks, two different solid phases exist. For intermediate sizes, only a disordered fluid phase is observed. The positional and orientational structure of the various phases are examined. We also compare the equations of state and the nematic-isotropic coexistence densities with those predicted by an extended Onsager theory using virial coefficients up to B(8).

Computer simulation and high level virial theory of Saturn-ring or UFO colloids

NASA Astrophysics Data System (ADS)

Bates, Martin A.; Dennison, Matthew; Masters, Andrew

2008-08-01

Monte Carlo simulations are used to map out the complete phase diagram of hard body UFO systems, in which the particles are composed of a concentric sphere and thin disk. The equation of state and phase behavior are determined for a range of relative sizes of the sphere and disk. We show that for relatively large disks, nematic and solid phases are observed in addition to the isotropic fluid. For small disks, two different solid phases exist. For intermediate sizes, only a disordered fluid phase is observed. The positional and orientational structure of the various phases are examined. We also compare the equations of state and the nematic-isotropic coexistence densities with those predicted by an extended Onsager theory using virial coefficients up to B8.

High-Pressure Synthesis: A New Frontier in the Search for Next-Generation Intermetallic Compounds.

PubMed

Walsh, James P S; Freedman, Danna E

2018-06-19

The application of high pressure adds an additional dimension to chemical phase space, opening up an unexplored expanse bearing tremendous potential for discovery. Our continuing mission is to explore this new frontier, to seek out new intermetallic compounds and new solid-state bonding. Simple binary elemental systems, in particular those composed of pairs of elements that do not form compounds under ambient pressures, can yield novel crystalline phases under compression. Thus, high-pressure synthesis can provide access to solid-state compounds that cannot be formed with traditional thermodynamic methods. An emerging approach for the rapid exploration of composition-pressure-temperature phase space is the use of hand-held high-pressure devices known as diamond anvil cells (DACs). These devices were originally developed by geologists as a way to study minerals under conditions relevant to the earth's interior, but they possess a host of capabilities that make them ideal for high-pressure solid-state synthesis. Of particular importance, they offer the capability for in situ spectroscopic and diffraction measurements, thereby enabling continuous reaction monitoring-a powerful capability for solid-state synthesis. In this Account, we provide an overview of this approach in the context of research we have performed in the pursuit of new intermetallic compounds. We start with a discussion of pressure as a fundamental experimental variable that enables the formation of intermetallic compounds that cannot be isolated under ambient conditions. We then introduce the DAC apparatus and explain how it can be repurposed for use as a synthetic vessel with which to explore this phase space, going to extremes of pressure where no chemist has gone before. The remainder of the Account is devoted to discussions of recent experiments we have performed with this approach that have led to the discovery of novel intermetallic compounds in the Fe-Bi, Cu-Bi, and Ni-Bi systems, with a focus on the cutting-edge methods that made these experiments possible. We review the use of in situ laser heating at high pressure, which led to the discovery of FeBi 2 , the first binary intermetallic compound in the Fe-Bi system. Our work in the Cu-Bi system is described in the context of in situ experiments carried out in the DAC to map its high-pressure phase space, which revealed two intermetallic phases (Cu 11 Bi 7 and CuBi). Finally, we review the discovery of β-NiBi, a novel high-pressure phase in the Ni-Bi system. We hope that this Account will inspire the next generation of solid-state chemists to boldly explore high-pressure phase space.

A resolution approach of racemic phenylalanine with aqueous two-phase systems of chiral tropine ionic liquids.

PubMed

Wu, Haoran; Yao, Shun; Qian, Guofei; Yao, Tian; Song, Hang

2015-10-30

Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu(2+) based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance. Copyright © 2015. Published by Elsevier B.V.

Solid-state diffusion-controlled growth of the phases in the Au-Sn system

NASA Astrophysics Data System (ADS)

Baheti, Varun A.; Kashyap, Sanjay; Kumar, Praveen; Chattopadhyay, Kamanio; Paul, Aloke

2018-01-01

The solid state diffusion-controlled growth of the phases is studied for the Au-Sn system in the range of room temperature to 200 °C using bulk and electroplated diffusion couples. The number of product phases in the interdiffusion zone decreases with the decrease in annealing temperature. These phases grow with significantly high rates even at the room temperature. The growth rate of the AuSn4 phase is observed to be higher in the case of electroplated diffusion couple because of the relatively small grains and hence high contribution of the grain boundary diffusion when compared to the bulk diffusion couple. The diffraction pattern analysis indicates the same equilibrium crystal structure of the phases in these two types of diffusion couples. The analysis in the AuSn4 phase relating the estimated tracer diffusion coefficients with grain size, crystal structure, the homologous temperature of experiments and the concept of the sublattice diffusion mechanism in the intermetallic compounds indicate that Au diffuses mainly via the grain boundaries, whereas Sn diffuses via both the grain boundaries and the lattice.

Temperature-Controlled High-Speed AFM: Real-Time Observation of Ripple Phase Transitions.

PubMed

Takahashi, Hirohide; Miyagi, Atsushi; Redondo-Morata, Lorena; Scheuring, Simon

2016-11-01

With nanometer lateral and Angstrom vertical resolution, atomic force microscopy (AFM) has contributed unique data improving the understanding of lipid bilayers. Lipid bilayers are found in several different temperature-dependent states, termed phases; the main phases are solid and fluid phases. The transition temperature between solid and fluid phases is lipid composition specific. Under certain conditions some lipid bilayers adopt a so-called ripple phase, a structure where solid and fluid phase domains alternate with constant periodicity. Because of its narrow regime of existence and heterogeneity ripple phase and its transition dynamics remain poorly understood. Here, a temperature control device to high-speed atomic force microscopy (HS-AFM) to observe dynamics of phase transition from ripple phase to fluid phase reversibly in real time is developed and integrated. Based on HS-AFM imaging, the phase transition processes from ripple phase to fluid phase and from ripple phase to metastable ripple phase to fluid phase could be reversibly, phenomenologically, and quantitatively studied. The results here show phase transition hysteresis in fast cooling and heating processes, while both melting and condensation occur at 24.15 °C in quasi-steady state situation. A second metastable ripple phase with larger periodicity is formed at the ripple phase to fluid phase transition when the buffer contains Ca 2+ . The presented temperature-controlled HS-AFM is a new unique experimental system to observe dynamics of temperature-sensitive processes at the nanoscopic level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-phase anaerobic digestion of source sorted OFMSW (organic fraction of municipal solid waste): performance and kinetic study.

PubMed

Pavan, P; Battistoni, P; Cecchi, F; Mata-Alvarez, J

2000-01-01

The results of a two-phase system operated in different conditions, treating the source-sorted organic fraction of municipal solid waste (SS-OFMSW), coming mainly from fruit and vegetable markets, are presented. Hydraulic retention time (HRT) in the hydrolytic reactor and in the methanogenic reactor and also the temperature in the hydrolytic reactor (mesophilic and thermophilic conditions) are varied in order to evaluate the effect of these factors. The methanogenic reactor is always operated within the thermophilic range. Optimum operating conditions are found to be around 12 days (total system) using the mesophilic range of temperature in the first reactor. Specific gas production (SGP) in these conditions is around 0.6 m3/kg TVS. A kinetic study is also carried out, using the first and the step diffusional models. The latter gives much better results, with fitted constants comparable to other studies. Finally, a comparison with a one-phase system is carried out, showing that a two-phase system is much more appropriate for the digestion of this kind of highly biodegradable substrate in thermophilic conditions.

Stabilized antiferroelectricity in xBiScO3-(1-x)NaNbO3 lead-free ceramics with established double hysteresis loops

NASA Astrophysics Data System (ADS)

Gao, Lisheng; Guo, Hanzheng; Zhang, Shujun; Randall, Clive A.

2018-02-01

We previously reported various solid solution systems that demonstrated the stabilized antiferroelectric (P) phases in NaNbO3 through lowering the tolerance factor. However, all those reported modifications were achieved by adding A2+B4+O3 type solid solutions. A lead-free antiferroelectric (AFE) solid solution xBiScO3-(1-x)NaNbO3 was rationalized by adopting the tolerance factor design rule. Specifically, adding BiScO3 was found to effectively stabilize the AFE phase without changing the crystal symmetry of NaNbO3. Microstructure and electron zone axis diffraction patterns from transmission electron microscopy revealed the stabilized AFE (P) phase in this solid solution. Besides, the electric-field-induced polarization with a double-hysteresis loop was observed. The present results pointed out that the strategy could also be applied while adding A3+B3+O3 type solid solutions. In addition, it expanded the compositional design that can be applied to antiferroelectric materials.

Buckling failure of square ice-nanotube arrays constrained in graphene nanocapillaries.

PubMed

Zhu, YinBo; Wang, FengChao; Wu, HengAn

2016-08-07

Graphene confinement provides a new physical and mechanical environment with ultrahigh van der Waals pressure, resulting in new quasi-two-dimensional phases of few-layer ice. Polymorphic transition can occur in bilayer constrained water/ice system. Here, we perform a comprehensive study of the phase transition of AA-stacked bilayer water constrained within a graphene nanocapillary. The compression-limit and superheating-limit (phase) diagrams are obtained, based on the extensive molecular-dynamics simulations at numerous thermodynamic states. Liquid-to-solid, solid-to-solid, and solid-to-liquid-to-solid phase transitions are observed in the compression and superheating of bilayer water. Interestingly, there is a temperature threshold (∼275 K) in the compression-limit diagram, which indicates that the first-order and continuous-like phase transitions of bilayer water depend on the temperature. Two obviously different physical processes, compression and superheating, display similar structural evolution; that is, square ice-nanotube arrays (BL-VHDI) will bend first and then transform into bilayer triangular AA stacking ice (BL-AAI). The superheating limit of BL-VHDI exhibits local maxima, while that of BL-AAI increases monotonically. More importantly, from a mechanics point of view, we propose a novel mechanism of the transformation from BL-VHDI to BL-AAI, both for the compression and superheating limits. This structural transformation can be regarded as the "buckling failure" of the square-ice-nanotube columns, which is dominated by the lateral pressure.

Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination.

PubMed

Mogolodi Dimpe, K; Mpupa, Anele; Nomngongo, Philiswa N

2018-01-05

This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5μgL -1 and 1.7μgL -1 , respectively, and intraday and interday precision expressed in terms of relative standard deviation were >6%.The maximum adsorption capacity was 138mgg -1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water. Copyright © 2017 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Panero, W. R.; Caracas, R.

2017-12-01

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

Coarsening in Solid-Liquid Mixtures Studied on the Space Shuttle

NASA Technical Reports Server (NTRS)

Caruso, John J.

1999-01-01

Ostwald ripening, or coarsening, is a process in which large particles in a two-phase mixture grow at the expense of small particles. It is a ubiquitous natural phenomena occurring in the late stages of virtually all phase separation processes. In addition, a large number of commercially important alloys undergo coarsening because they are composed of particles embedded in a matrix. Many of them, such as high-temperature superalloys used for turbine blade materials and low-temperature aluminum alloys, coarsen in the solid state. In addition, many alloys, such as the tungsten-heavy metal systems, coarsen in the solid-liquid state during liquid phase sintering. Numerous theories have been proposed that predict the rate at which the coarsening process occurs and the shape of the particle size distribution. Unfortunately, these theories have never been tested using a system that satisfies all the assumptions of the theory. In an effort to test these theories, NASA studied the coarsening process in a solid-liquid mixture composed of solid tin particles in a liquid lead-tin matrix. On Earth, the solid tin particles float to the surface of the sample, like ice in water. In contrast, in a microgravity environment this does not occur. The microstructures in the ground- and space-processed samples (see the photos) show clearly the effects of gravity on the coarsening process. The STS-83-processed sample (right image) shows nearly spherical uniformly dispersed solid tin particles. In contrast, the identically processed, ground-based sample (left image) shows significant density-driven, nonspherical particles, and because of the higher effective solid volume fraction, a larger particle size after the same coarsening time. The "Coarsening in Solid-Liquid Mixtures" (CSLM) experiment was conducted in the Middeck Glovebox facility (MGBX) flown aboard the shuttle in the Microgravity Science Laboratory (MSL-1/1R) on STS-83/94. The primary objective of CSLM is to measure the temporal evolution of the solid particles during coarsening.

SOME RARE-EARTH ALLOY SYSTEMS. I. La-Gd, La-Y, Gd-Y

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

Spedding, F.H.; Valletta, R.M.; Daane, A.H.

The La-Y, La--Gd, and Gd--Y alloy systems were examined by conventional metallurgical research techniques. As would be expected from the similarity of the parent metals, the Gd--Y system exhibits complete solid solubility across the system in both the alpha and beta regions, with nearly perfect behavior indicated by the essentially linear plots of lattice constants and other related data, The La--Y and La--Gd systems show complete solid solubility in the high temperature bcc region, with limited solubility in the room temperature forms. In the central region of these two systems at room temperature, an ordered phase with the samarium structuremore » is observed, Some correlation of structure and lattice constants of this phase with the properties of the related pure metals is observed. (auth)« less

Coupled flow and deformations in granular systems beyond the pendular regime

NASA Astrophysics Data System (ADS)

Yuan, Chao; Chareyre, Bruno; Darve, Felix

2017-06-01

A pore-scale numerical model is proposed for simulating the quasi-static primary drainage and the hydro-mechanical couplings in multiphase granular systems. The solid skeleton is idealized to a dense random packing of polydisperse spheres by DEM. The fluids (nonwetting and wetting phases) space is decomposed to a network of tetrahedral pores based on the Regular Triangulation method. The local drainage rules and invasion logic are defined. The fluid forces acting on solid grains are formulated. The model can simulate the hydraulic evolution from a fully saturated state to a low level of saturation but beyond the pendular regime. The features of wetting phase entrapments and capillary fingering can also be reproduced. Finally, a primary drainage test is performed on a 40,000 spheres of sample. The water retention curve is obtained. The solid skeleton first shrinks then swells.

Simultaneous determination of azathioprine and 6-mercaptopurine by high-performance liquid chromatography.

PubMed

Van Os, E C; McKinney, J A; Zins, B J; Mays, D C; Schriver, Z H; Sandborn, W J; Lipsky, J J

1996-04-26

A specific, sensitive, single-step solid-phase extraction and reversed-phase high-performance liquid chromatographic method for the simultaneous determination of plasma 6-mercaptopurine and azathioprine concentrations is reported. Following solid-phase extraction, analytes are separated on a C18 column with mobile phase consisting of 0.8% acetonitrile in 1 mM triethylamine, pH 3.2, run on a gradient system. Quantitation limits were 5 ng/ml and 2 ng/ml for azathioprine and 6-mercaptopurine, respectively. Peak heights correlated linearly to known extracted standards for 6-mercaptopurine and azathioprine (r = 0.999) over a range of 2-200 ng/ml. No chromatographic interferences were detected.

Dipolar recoupling in solid state NMR by phase alternating pulse sequences

PubMed Central

Lin, J.; Bayro, M.; Griffin, R. G.; Khaneja, N.

2009-01-01

We describe some new developments in the methodology of making heteronuclear and homonuclear recoupling experiments in solid state NMR insensitive to rf-inhomogeneity by phase alternating the irradiation on the spin system every rotor period. By incorporating delays of half rotor periods in the pulse sequences, these phase alternating experiments can be made γ encoded. The proposed methodology is conceptually different from the standard methods of making recoupling experiments robust by the use of ramps and adiabatic pulses in the recoupling periods. We show how the concept of phase alternation can be incorporated in the design of homonuclear recoupling experiments that are both insensitive to chemical-shift dispersion and rf-inhomogeneity. PMID:19157931

Revisiting low-fidelity two-fluid models for gas–solids transport

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

Adeleke, Najeem, E-mail: najm@psu.edu; Adewumi, Michael, E-mail: m2a@psu.edu; Ityokumbul, Thaddeus

Two-phase gas–solids transport models are widely utilized for process design and automation in a broad range of industrial applications. Some of these applications include proppant transport in gaseous fracking fluids, air/gas drilling hydraulics, coal-gasification reactors and food processing units. Systems automation and real time process optimization stand to benefit a great deal from availability of efficient and accurate theoretical models for operations data processing. However, modeling two-phase pneumatic transport systems accurately requires a comprehensive understanding of gas–solids flow behavior. In this study we discuss the prevailing flow conditions and present a low-fidelity two-fluid model equation for particulate transport. The modelmore » equations are formulated in a manner that ensures the physical flux term remains conservative despite the inclusion of solids normal stress through the empirical formula for modulus of elasticity. A new set of Roe–Pike averages are presented for the resulting strictly hyperbolic flux term in the system of equations, which was used to develop a Roe-type approximate Riemann solver. The resulting scheme is stable regardless of the choice of flux-limiter. The model is evaluated by the prediction of experimental results from both pneumatic riser and air-drilling hydraulics systems. We demonstrate the effect and impact of numerical formulation and choice of numerical scheme on model predictions. We illustrate the capability of a low-fidelity one-dimensional two-fluid model in predicting relevant flow parameters in two-phase particulate systems accurately even under flow regimes involving counter-current flow.« less

Investigation of the phase relations in the U-Al-Ge ternary system: Influence of the Al/Ge substitution on the properties of the intermediate phases

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

Moussa, C.; El Sayah, Z.; Chajewski, G.

The phase relations within the U-Al-Ge ternary system were studied for two isothermal sections, at 673 K for the whole Gibbs triangle and at 1173 K for the concentration range 25–100 at% U. The identification of the phases, their composition ranges and stability were determined by x-ray powder diffraction, scanning electron microscopy coupled to energy dispersive spectroscopy and differential thermal analysis. The tie-lines and the solubility domains were determined for the U-Ge and U-Al binaries, the UAl{sub 3}-UGe{sub 3} solid-solution and for the unique ternary intermediate phase U{sub 3}Al{sub 2−x}Ge{sub 3+x}. The experimental isopleth section of the pseudo-binary UAl{sub 3}-UGe{submore » 3} reveals an isomorphous solid solution based on the Cu{sub 3}Au-type below the solidus. The U{sub 3}Al{sub 2−x}Ge{sub 3+x} solid solution extends for −0.1≤x≤1.35 and −0.2≤x≤1.5 at 673 K and 1173 K respectively. It crystallizes in the I-centered tetragonal symmetry. The reciprocal lattice of several compositions of the U{sub 3}Al{sub 2−x}Ge{sub 3+x} solid solution was examined by electron diffraction at room temperature, revealing the presence of a c-glide plane. Their crystal structure was refined by single crystal x-ray diffraction suggesting an isomorphous solid solution best described with the non-centrosymmetric space group I4cm in the paramagnetic domain. The magnetic measurements confirm the ferromagnetic ordering of the solid solution U{sub 3}Al{sub 2−x}Ge{sub 3+x} with an increase of Tc with the Al content. The thermal variation of the specific heat bear out the magnetic transitions with some delocalized character of the uranium 5f electrons. - Graphical abstract: The phase relations within the U-Al-Ge ternary system were experimentally assessed for two isothermal sections, at 673 K for the whole Gibbs triangle and at 1173 K for the concentration range 25–100 at% U. A complete UAl{sub 3}-UGe{sub 3} solid-solution based on the Cu{sub 3}Au-type forms below the solidus. A unique ternary phase showing a large homogeneity domain, U{sub 3}Al{sub 2−x}Ge{sub 3+x} for −0.1≤x≤1.35 and −0.2≤x≤1.5 at 673 K and 1173 K respectively has been evidenced. It is best described with the non-centrosymmetric space group I4cm above room temperature. A linear increase of the ferromagnetic ordering is observed with the Al content. - Highlights: • Isothermal sections of the U-Al-Ge system were investigated for 673 K and 1173 K. • An isomorphous solid-solution UAl{sub 3}-UGe{sub 3} forms for the whole composition range. • U{sub 3}Al{sub 2−x}Ge{sub 3+x} the unique ternary phase to form exists for a large homogeneity domain. • U{sub 3}Al{sub 2−x}Ge{sub 3+x} is best described in I4cm space group above room temperature. • The ferromagnetic transition of U{sub 3}Al{sub 2−x}Ge{sub 3+x} linearly increases with the Al content.« less

Understanding the Impact of Water on the Miscibility and Microstructure of Amorphous Solid Dispersions: An AFM-LCR and TEM-EDX Study.

PubMed

Li, Na; Gilpin, Christopher J; Taylor, Lynne S

2017-05-01

Miscibility is critical for amorphous solid dispersions (ASDs). Phase-separated ASDs are more prone to crystallization, and thus can lose their solubility advantage leading to product failure. Additionally, dissolution performance can be diminished as a result of phase separation in the ASD matrix. Water is known to induce phase separation during storage for some ASDs. However, the impact of water introduced during preparation has not been as thoroughly investigated to date. The purpose of this study was to develop a mechanistic understanding of the effect of water on the phase behavior and microstructure of ASDs. Evacetrapib and two polymers were selected as the model system. Atomic force microscopy coupled with Lorentz contact resonance, and transmission electron microscopy with energy dispersive X-ray spectroscopy were employed to evaluate the microstructure and composition of phase-separated ASDs. It was found that phase separation could be induced via two routes: solution-state phase separation during ASD formation caused by water absorption during film formation by a hydrophilic solvent, or solid-phase separation following exposure to high RH during storage. Water contents of as low as 2% in the organic solvent system used to dissolve the drug and polymer were found to result in phase separation in the resultant ASD film. These findings have profound implications on lab-scale ASD preparation and potentially also for industrial production. Additionally, these high-resolution imaging techniques combined with orthogonal analyses are powerful tools to visualize structural changes in ASDs, which in turn will enable better links to be made between ASD structure and performance.

Development of solid-gas equilibrium propulsion system for small spacecraft

NASA Astrophysics Data System (ADS)

Chujo, Toshihiro; Mori, Osamu; Kubo, Yuki

2017-11-01

A phase equilibrium propulsion system is a kind of cold-gas jet in which the phase equilibrium state of the fuel is maintained in a tank and its vapor is ejected when a valve is opened. One such example is a gas-liquid equilibrium propulsion system that uses liquefied gas as fuel. This system was mounted on the IKAROS solar sail and has been demonstrated in orbit. The system has a higher storage efficiency and a lighter configuration than a high-pressure cold-gas jet because the vapor pressure is lower, and is suitable for small spacecraft. However, the system requires a gas-liquid separation device in order to avoid leakage of the liquid, which makes the system complex. As another example of a phase equilibrium propulsion system, we introduce a solid-gas equilibrium propulsion system, which uses a sublimable substance as fuel and ejects its vapor. This system has an even lower vapor pressure and does not require such a separation device, instead requiring only a filter to keep the solid inside the tank. Moreover, the system is much simpler and lighter, making it more suitable for small spacecraft, especially CubeSat-class spacecraft, and the low thrust of the system allows spacecraft motion to be controlled precisely. In addition, the thrust level can be controlled by controlling the temperature of the fuel, which changes the vapor pressure. The present paper introduces the concept of the proposed system, and describes ejection experiments and its evaluation. The basic function of the proposed system is demonstrated in order to verify its usefulness.

Phase-field modeling of diffusional phase behaviors of solid surfaces: A case study of phase-separating Li XFePO 4 electrode particles

DOE PAGES

Heo, Tae Wook; Chen, Long-Qing; Wood, Brandon C.

2015-04-08

In this paper, we present a comprehensive phase-field model for simulating diffusion-mediated kinetic phase behaviors near the surface of a solid particle. The model incorporates elastic inhomogeneity and anisotropy, diffusion mobility anisotropy, interfacial energy anisotropy, and Cahn–Hilliard diffusion kinetics. The free energy density function is formulated based on the regular solution model taking into account the possible solute-surface interaction near the surface. The coherency strain energy is computed using the Fourier-spectral iterative-perturbation method due to the strong elastic inhomogeneity with a zero surface traction boundary condition. Employing a phase-separating Li XFePO 4 electrode particle for Li-ion batteries as a modelmore » system, we perform parametric three-dimensional computer simulations. The model permits the observation of surface phase behaviors that are different from the bulk counterpart. For instance, it reproduces the theoretically well-established surface modes of spinodal decomposition of an unstable solid solution: the surface mode of coherent spinodal decomposition and the surface-directed spinodal decomposition mode. We systematically investigate the influences of major factors on the kinetic surface phase behaviors during the diffusional process. Finally, our simulation study provides insights for tailoring the internal phase microstructure of a particle by controlling the surface phase morphology.« less

Quantum phases of dipolar soft-core bosons

NASA Astrophysics Data System (ADS)

Grimmer, D.; Safavi-Naini, A.; Capogrosso-Sansone, B.; Söyler, Ş. G.

2014-10-01

We study the phase diagram of a system of soft-core dipolar bosons confined to a two-dimensional optical lattice layer. We assume that dipoles are aligned perpendicular to the layer such that the dipolar interactions are purely repulsive and isotropic. We consider the full dipolar interaction and perform path-integral quantum Monte Carlo simulations using the worm algorithm. Besides a superfluid phase, we find various solid and supersolid phases. We show that, unlike what was found previously for the case of nearest-neighbor interaction, supersolid phases are stabilized by doping the solids not only with particles but with holes as well. We further study the stability of these quantum phases against thermal fluctuations. Finally, we discuss pair formation and the stability of the pair checkerboard phase formed in a bilayer geometry, and we suggest experimental conditions under which the pair checkerboard phase can be observed.

Control of ice chromatographic retention mechanism by changing temperature and dopant concentration.

PubMed

Tasaki, Yuiko; Okada, Tetsuo

2011-12-15

A liquid phase coexists with solid water ice in a typical binary system, such as NaCl-water, in the temperature range between the freezing point and the eutectic point (t(eu)) of the system. In ice chromatography with salt-doped ice as the stationary phase, both solid and liquid phase can contribute to solute retention in different fashions; that is, the solid ice surface acts as an adsorbent, while a solute can be partitioned into the liquid phase. Thus, both adsorption and partition mechanisms can be utilized for ice chromatographic separation. An important feature in this approach is that the liquid phase volume can be varied by changing the temperature and the concentration of a salt incorporated into the ice stationary phase. Thus, we can control the relative contribution from the partition mechanism in the entire retention because the liquid phase volume can be estimated from the freezing depression curve. Separation selectivity can thereby be modified. The applicability of this concept has been confirmed for the solutes of different adsorption and partition abilities. The predicted retention based on thermodynamics basically agrees well with the corresponding experimental retention. However, one important inconsistency has been found. The calculation predicts a step-like discontinuity of the solute retention at t(eu) because the phase diagram suggests that the liquid phase abruptly appears at t(eu) when the temperature increases. In contrast, the corresponding experimental plots are continuous over the wider range including the subeutectic temperatures. This discrepancy is explained by the existence of the liquid phase below t(eu). A difference between predicted and measured retention factors allows the estimation of the volume of the subeutectic liquid phase.

Feasibility study of a low-energy gamma ray system for measuring quantity and flow rate of slush hydrogen

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Shen, Chih-Ping; Sprinkle, Danny R.

1992-01-01

As part of a study to demonstrate the suitability of an X-ray or gamma ray probe for monitoring the quality and flow rate of slush hydrogen, mass attenuation coefficients for Cd-109 X- and gamma radiation in five chemical compounds were measured. The Ag-109 K rays were used for water and acetic acid, whereas E3 transition from the first excited state at 87.7 keV in Ag-109 provided the probe radiation for bromobenzene, alpha (exp 2) chloroisodurene, and cetyl bromide. Measurements were made for a single phase (gas, liquid, solid) as well as mixed phases (liquid plus solid) in all cases. It was shown that the mass attenuation coefficient for the selected radiations is independent of the phase of the test fluids or phase ratios in the case of mixed phase fluids. Described here are the procedure and the results for the five fluid systems investigated.

Phase equilibria in the Bi 2TeO 5Bi 2SeO 5 system and a high temperature neutron powder diffraction study of Bi 2SeO 5

NASA Astrophysics Data System (ADS)

Dityatyev, Oleg A.; Smidt, Peer; Stefanovich, Sergey Yu; Lightfoot, Philip; Dolgikh, Valery A.; Opperman, Heinrich

2004-09-01

Phase equilibria in the Bi 2TeO 5Bi 2SeO 5 system were studied by X-ray, DTA and second harmonic generation (SHG). The samples were synthesized by solid state reactions of the Bi, Te and Se oxides. The phase diagram is interpreted as a quasibinary peritectic one with wide ranges of solid solutions on the basis of both compounds. The SHG study showed Bi 2SeO 5 to undergo a phase transition at about 250 °C. Neutron diffraction (25-650 °C) showed no major changes in the structure of Bi 2SeO 5 at high temperatures. However, the analysis of the oxygen atom thermal factors and site occupancies suggested that the mechanism of the phase transformation is an order-disorder transition involving reorientation of the SeO 3 group.

Satellite Power System (SPS) environmental impacts, preliminary assessment

NASA Technical Reports Server (NTRS)

Livingston, F. R.

1978-01-01

Present power plant assessment factors are used to present satellite power system (SPS) impacts. In contrast to oil, gas, nuclear and coal fueled power plants, the SPS and hydroelectric power plants produce air, water, and solid waste emissions only during the construction phase. Land use impacts result from the placement of rectennas used for microwave receiving and rectifying. Air quality impacts of the SPS resulting from the construction phase amount to 0.405 metric tons per megawatt year. Solid wastes impacts are 0.108 metric tons per year of operation. Other impacts such as those caused by heavy lift launch vehicle sites are also discussed.

The Formation and Stability of Carbonic Acid on Outer Solar System Bodies

NASA Technical Reports Server (NTRS)

Peeters, Z.; Hudson, R. L.; Moore, M. H.; Lewis, Ariel

2009-01-01

The radiation chemistry, thermal stability, and vapor pressure of solid-phase carbonic acid (H2CO3) have been studied with mid-infrared spectroscopy. A new procedure for measuring this molecule's radiation stability has been used to obtain intrinsic IR band strengths and half-lives for radiolytic destruction. Results are compared to literature values. We report, for the first time, measurements of carbonic acid's vapor pressure and its heat of sublimation. We also report the first observation of a chemical reaction involving solid-phase carbonic acid. Possible applications of these findings are discussed, with an emphasis on the outer Solar System.

Phase Behavior of Complex Superprotonic Solid Acids

NASA Astrophysics Data System (ADS)

Panithipongwut, Chatr

Superprotonic phase transitions and thermal behaviors of three complex solid acid systems are presented, namely Rb3H(SO4) 2-RbHSO4 system, Rb3H(SeO4)2-Cs 3H(SeO4)2 solid solution system, and Cs6 (H2SO4)3(H1.5PO4) 4. These material systems present a rich set of phase transition characteristics that set them apart from other, simpler solid acids. A.C. impedance spectroscopy, high-temperature X-ray powder diffraction, and thermal analysis, as well as other characterization techniques, were employed to investigate the phase behavior of these systems. Rb3H(SO4)2 is an atypical member of the M3H(XO4)2 class of compounds (M = alkali metal or NH4+ and X = S or Se) in that a transition to a high-conductivity state involves disproportionation into two phases rather than a simple polymorphic transition [1]. In the present work, investigations of the Rb3H(SO4)2-RbHSO4 system have revealed the disproportionation products to be Rb2SO 4 and the previously unknown compound Rb5H3(SO 4)4. The new compound becomes stable at a temperature between 25 and 140 °C and is isostructural to a recently reported trigonal phase with space group P3m of Cs5H 3(SO4)4 [2]. At 185 °C the compound undergoes an apparently polymorphic transformation with a heat of transition of 23.8 kJ/mol and a slight additional increase in conductivity. The compounds Rb3H(SeO4)2 and Cs 3H(SeO4)2, though not isomorphous at ambient temperatures, are quintessential examples of superprotonic materials. Both adopt monoclinic structures at ambient temperatures and ultimately transform to a trigonal (R3m) superprotonic structure at slightly elevated temperatures, 178 and 183 °C, respectively. The compounds are completely miscible above the superprotonic transition and show extensive solubility below it. Beyond a careful determination of the phase boundaries, we find a remarkable 40-fold increase in the superprotonic conductivity in intermediate compositions rich in Rb as compared to either end-member. The compound Cs6(H2SO4)3(H 1.5PO4)4 is unusual amongst solid acid compounds in that it has a complex cubic structure at ambient temperature and apparently transforms to a simpler cubic structure of the CsCl-type (isostructural with CsH2PO4) at its transition temperature of 100-120 °C [3]. Here it is found that, depending on the level of humidification, the superprotonic transition of this material is superimposed with a decomposition reaction, which involves both exsolution of (liquid) acid and loss of H2O. This reaction can be suppressed by application of sufficiently high humidity, in which case Cs6(H2SO4)3(H 1.5PO4)4 undergoes a true superprotonic transition. It is proposed that, under conditions of low humidity, the decomposition/dehydration reaction transforms the compound to Cs6(H2-0.5xSO 4)3(H1.5PO4)4-x, also of the CsCl structure type at the temperatures of interest, but with a smaller unit cell. With increasing temperature, the decomposition/dehydration proceeds to greater and greater extent and unit cell of the solid phase decreases. This is identified to be the source of the apparent negative thermal expansion behavior. References: [1] L.A. Cowan, R.M. Morcos, N. Hatada, A. Navrotsky, S.M. Haile, Solid State Ionics 179 (2008) (9-10) 305. [2] M. Sakashita, H. Fujihisa, K.I. Suzuki, S. Hayashi, K. Honda, Solid State Ionics 178 (2007) (21-22) 1262. [3] C.R.I. Chisholm, Superprotonic Phase Transitions in Solid Acids: Parameters affecting the presence and stability of superprotonic transitions in the MHnXO4 family of compounds (X=S, Se, P, As; M=Li, Na, K, NH4, Rb, Cs), Materials Science, California Institute of Technology, Pasadena, California (2003).

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

Zhu, Yi; Cai, Zhonghou; Chen, Pice

Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase seperated regions. The ability to simultanousely track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of- the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO 2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation ismore » initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO 2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, which is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO 2. Lastly, the direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.« less

Thermodynamic study of (anthracene + benzo[a]pyrene) solid mixtures

PubMed Central

Rice, James W.; Suuberg, Eric M.

2010-01-01

To characterize better the thermodynamic behavior of a binary polycyclic aromatic hydrocarbon mixture, thermochemical and vapor pressure experiments were used to examine the phase behavior of the {anthracene (1) + benzo[a]pyrene (2)} system. A solid-liquid phase diagram was mapped for the mixture. A eutectic point occurs at x1 = 0.26. The eutectic mixture is an amorphous solid that lacks organized crystal structure and melts between T = (414 and 420) K. For mixtures that contain 0.10 < x1 < 0.90, the enthalpy of fusion is dominated by that of the eutectic. Solid-vapor equilibrium studies show that mixtures of anthracene and benzo[a]pyrene at x1 < 0.10 sublime at the vapor pressure of pure benzo[a]pyrene. These results suggest that the solid-vapor equilibrium of benzo[a]pyrene is not significantly influenced by moderate levels of anthracene in the crystal structure. PMID:20814451

Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

2016-07-01

Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solid platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface. The heat transfer rate is also much higher in case of hydrophilic surface.

Single-phase and two-phase anaerobic digestion of fruit and vegetable waste: Comparison of start-up, reactor stability and process performance

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

Ganesh, Rangaraj; Torrijos, Michel, E-mail: michel.torrijos@supagro.inra.fr; Sousbie, Philippe

Highlights: • Single-phase and two-phase systems were compared for fruit and vegetable waste digestion. • Single-phase digestion produced a methane yield of 0.45 m{sup 3} CH{sub 4}/kg VS and 83% VS removal. • Substrate solubilization was high in acidification conditions at 7.0 kg VS/m{sup 3} d and pH 5.5–6.2. • Energy yield was lower by 33% for two-phase system compared to the single-phase system. • Simple and straight-forward operation favored single phase process over two-phase process. - Abstract: Single-phase and two-phase digestion of fruit and vegetable waste were studied to compare reactor start-up, reactor stability and performance (methane yield, volatilemore » solids reduction and energy yield). The single-phase reactor (SPR) was a conventional reactor operated at a low loading rate (maximum of 3.5 kg VS/m{sup 3} d), while the two-phase system consisted of an acidification reactor (TPAR) and a methanogenic reactor (TPMR). The TPAR was inoculated with methanogenic sludge similar to the SPR, but was operated with step-wise increase in the loading rate and with total recirculation of reactor solids to convert it into acidification sludge. Before each feeding, part of the sludge from TPAR was centrifuged, the centrifuge liquid (solubilized products) was fed to the TPMR and centrifuged solids were recycled back to the reactor. Single-phase digestion produced a methane yield of 0.45 m{sup 3} CH{sub 4}/kg VS fed and VS removal of 83%. The TPAR shifted to acidification mode at an OLR of 10.0 kg VS/m{sup 3} d and then achieved stable performance at 7.0 kg VS/m{sup 3} d and pH 5.5–6.2, with very high substrate solubilization rate and a methane yield of 0.30 m{sup 3} CH{sub 4}/kg COD fed. The two-phase process was capable of high VS reduction, but material and energy balance showed that the single-phase process was superior in terms of volumetric methane production and energy yield by 33%. The lower energy yield of the two-phase system was due to the loss of energy during hydrolysis in the TPAR and the deficit in methane production in the TPMR attributed to COD loss due to biomass synthesis and adsorption of hard COD onto the flocs. These results including the complicated operational procedure of the two-phase process and the economic factors suggested that the single-phase process could be the preferred system for FVW.« less

X-ray diffraction study of laser-driven solid-state diffusional mixing and new phase formation in Ni-Pt multilayers [X-ray diffraction study of laser-driven solid-state diffusional mixing and new phase formation

DOE PAGES

Kelly, B. G.; Loether, A.; Unruh, K. M.; ...

2017-02-01

An in situ optical pump and x-ray probe technique has been utilized to study photoinitiated solid-state diffusion in a Ni-Pt multilayer system. Hard x-ray diffraction has been used to follow the systematic growth of the NiPt alloy as a function of laser intensity and total energy deposited. It is observed that new phase growth can be driven in as little as one laser pulse, and that repeated photoexcitation can completely convert the entire multilayer structure into a single metallic alloy. In conclusion, the data suggest that lattice strain relaxation takes place prior to atomic diffusion and the formation of amore » NiPt alloy.« less

Solid-phase synthesis of self-assembling multivalent π-conjugated peptides

DOE PAGES

Sanders, Allix M.; Kale, Tejaswini S.; Katz, Howard E.; ...

2017-02-07

Here, we present a completely solid-phase synthetic strategy to create three- and four-fold peptide-appended π-electron molecules, where the multivalent oligopeptide presentation is dictated by the symmetries of reactive handles placed on discotic π-conjugated cores. Carboxylic acid and anhydride groups were viable amidation and imidation partners, respectively, and oligomeric π-electron discotic cores were prepared through Pd-catalyzed cross-couplings. Due to intermolecular hydrogen bonding between the three or four peptide axes, these π-peptide hybrids self-assemble into robust one-dimensional nanostructures with high aspect ratios in aqueous solution. The preparation of these systems via solid-phase methods will be detailed along with their self-assembly properties, asmore » revealed by steady-state spectroscopy and transmission electron microscopy and electrical characterization using field-effect transistor measurements.« less

X-ray diffraction study of laser-driven solid-state diffusional mixing and new phase formation in Ni-Pt multilayers [X-ray diffraction study of laser-driven solid-state diffusional mixing and new phase formation

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

Kelly, B. G.; Loether, A.; Unruh, K. M.

An in situ optical pump and x-ray probe technique has been utilized to study photoinitiated solid-state diffusion in a Ni-Pt multilayer system. Hard x-ray diffraction has been used to follow the systematic growth of the NiPt alloy as a function of laser intensity and total energy deposited. It is observed that new phase growth can be driven in as little as one laser pulse, and that repeated photoexcitation can completely convert the entire multilayer structure into a single metallic alloy. In conclusion, the data suggest that lattice strain relaxation takes place prior to atomic diffusion and the formation of amore » NiPt alloy.« less

DNA purification by triplex-affinity capture and affinity capture electrophoresis

DOEpatents

Cantor, Charles R.; Ito, Takashi; Smith, Cassandra L.

1996-01-01

The invention provides a method for purifying or isolating double stranded DNA intact using triple helix formation. The method includes the steps of complexing an oligonucleotide and double stranded DNA to generate a triple helix and immobilization of the triple helix on a solid phase by means of a molecular recognition system such as avidin/biotin. The purified DNA is then recovered intact by treating the solid phase with a reagent that breaks the bonds between the oligonucleotide and the intact double stranded DNA while not affecting the Watson-Crick base pairs of the double helix. The present invention also provides a method for purifying or isolating double stranded DNA intact by complexing the double stranded DNA with a specific binding partner and recovering the complex during electrophoresis by immobilizing it on a solid phase trap imbedded in an electrophoretic gel.

An effect of surface properties on detachment of adhered solid to cooling surface for formation of clathrate hydrate slurry

NASA Astrophysics Data System (ADS)

Daitoku, Tadafumi; Utaka, Yoshio

In air-conditioning systems, it is desirable that the liquid-solid phase change temperature of a cool energy storage material is approximately 10 °C from the perspective of improving coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra-n-butylammonium Bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of the heat transfer surface properties on the scraping force for detachment of adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally.

Phase Diagram of Quaternary System NaBr-KBr-CaBr2-H2O at 323 K

NASA Astrophysics Data System (ADS)

Cui, Rui-Zhi; Wang, Wei; Yang, Lei; Sang, Shi-Hua

2018-03-01

The phase equilibria in the system NaBr-KBr-CaBr2-H2O at 323 K were studied using the isothermal dissolution equilibrium method. Using the experimental solubilities of salts data, phase diagram was constructed. The phase diagram have two invariant points, five univariant curves, and four crystallization fields. The equilibrium solid phases in the system are NaBr, NaBr · 2H2O, KBr, and CaBr2 · 4H2O. The solubilities of salts in the system at 323 K were calculated by Pitzer's equation. There is shown that the calculated solubilities agree well with experimental data.

Anderson localization and Mott insulator phase in the time domain

PubMed Central

Sacha, Krzysztof

2015-01-01

Particles in space periodic potentials constitute standard models for investigation of crystalline phenomena in solid state physics. Time periodicity of periodically driven systems is a close analogue of space periodicity of solid state crystals. There is an intriguing question if solid state phenomena can be observed in the time domain. Here we show that wave-packets localized on resonant classical trajectories of periodically driven systems are ideal elements to realize Anderson localization or Mott insulator phase in the time domain. Uniform superpositions of the wave-packets form stationary states of a periodically driven particle. However, an additional perturbation that fluctuates in time results in disorder in time and Anderson localization effects emerge. Switching to many-particle systems we observe that depending on how strong particle interactions are, stationary states can be Bose-Einstein condensates or single Fock states where definite numbers of particles occupy the periodically evolving wave-packets. Our study shows that non-trivial crystal-like phenomena can be observed in the time domain. PMID:26074169

Solar power satellite system definition study, volume 4, phase 2

NASA Technical Reports Server (NTRS)

1979-01-01

Results of an overall evaluation of the solar power satellite concept are reported. Specific topics covered include: solid state sandwich configuration; parametric development of reliability design; power distribution system for solid state solar power satellites; multibeam transmission; GEO base system configuration; suppression of the heavy lift launch vehicle trajectory; conceptual design of an offshore space center facility; solar power satellite development and operations scenario; and microwave power transmission technology, advancement, development, and facility requirements.

Two-Step Vapor/Liquid/Solid Purification

NASA Technical Reports Server (NTRS)

Holland, L. R.

1986-01-01

Vertical distillation system combines in single operation advantages of multiple zone refining with those of distillation. Developed specifically to load Bridgman-Stockbarger (vertical-solidification) growth ampoules with ultrapure tellurium and cadmium, system, with suitable modifications, serves as material refiner. In first phase of purification process, ampoule heated to drive off absorbed volatiles. Second phase, evaporator heated to drive off volatiles in charge. Third phase, slowly descending heater causes distillation from evaporator to growing crystal in ampoule.

Structural characterization of a magnetic granular system under a time-dependent magnetic field: Voronoi tessellation and multifractal analysis

NASA Astrophysics Data System (ADS)

Moctezuma, R. E.; Arauz-Lara, J. L.; Donado, F.

2018-04-01

The structure of a two-dimensional magnetic granular system was determined by multifractal and Voronoi polygon analysis for a wide range of particle concentrations. Randomizing of the particle motions are produced by applying to the system a time-dependent sinusoidal magnetic field directed along the vertical direction. Both repulsive and attractive short-range interactions between the particles are induced. A direct observation of such system shows qualitatively that, as particle concentration increases, the structure evolves from being liquid-like at low particle concentrations to solid-like at high concentrations. We observe the formation of clusters which are small and weakly bonded and short-lived at low concentrations. Above a threshold particle concentration, clusters grow larger and are more strongly attached. In the system, one can distinguish the mobile particles from the immobile particles belonging to clusters, they can be considered separately as two different phases, a fluid and a solid. We determined the information entropy of the system as a whole and separately from each phase as particle concentration increases. The distribution of the Voronoi polygon areas are well fitted by a two-parameter gamma distribution and we have found that the regularity factor shows a notable change when pieces of the solid phase start to form. The methods we use here show that they can use even when the system is heterogeneous and they provide information when changes start.

Solid-phase extraction-gas chromatography and solid-phase extraction-gas chromatography-mass spectrometry determination of corrosion inhibiting long-chain primary alkyl amines in chemical treatment of boiler water in water-steam systems of power plants.

PubMed

Kusch, Peter; Knupp, Gerd; Hergarten, Marcus; Kozupa, Marian; Majchrzak, Maria

2006-04-28

Gas chromatography with simultaneous flame-ionization detection (FID) and a nitrogen-phosphorus detection (NPD) as well as gas chromatography-mass spectrometry (GC/MS) has been used to characterize long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and negative chemical ionization (NCI) mass spectra of trifluoroacetylated derivatives of the identified tert-octadecylamines are presented for the first time. The corrosion inhibiting alkyl amines were applied in a water-steam circuit of energy systems in the power industry. Solid-phase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated tert-octadecylamines in boiler water, superheated steam and condensate samples from the power plant. The estimated values were: 89 microg l(-1)(n = 5, RSD = 7.8%), 45 microg l(-1) (n = 5, RSD = 5.4%) and 37 microg l(-1)(n = 5, RSD = 2.3%), respectively.

Lyophilization -Solid Waste Treatment

NASA Technical Reports Server (NTRS)

Litwiller, Eric; Flynn, Michael; Fisher, John; Reinhard, Martin

2004-01-01

This paper discusses the development of a solid waste treatment system that has been designed for a Mars transit exploration mission. The technology described is an energy-efficient lyophilization technique that is designed to recover water from spacecraft solid wastes. Candidate wastes include feces, concentrated brines from water processors, and other solid wastes that contain free water. The system is designed to operate as a stand-alone process or to be integrated into the International Space Station Waste Collection System. In the lyophilization process, water in an aqueous waste is frozen and then sublimed, separating the waste into a dried solid material and liquid water. The sublimed water is then condensed in a solid ice phase and then melted to generate a liquid product. In the subject system the waste solids are contained within a 0.2 micron bio-guard bag and after drying are removed from the system and stored in a secondary container. This technology is ideally suited to applications such as the Mars Reference Mission, where water recovery rates approaching 100% are desirable but production of CO2 is not. The system is designed to minimize power consumption through the use of thermoelectric heat pumps. The results of preliminary testing of a prototype system and testing of the final configuration are provided. A mathematical model of the system is also described.

Phase Equilibria and Magnetic Phases in the Ce-Fe-Co-B System

PubMed Central

Wang, Tian; Kevorkov, Dmytro; Medraj, Mamoun

2016-01-01

Ce-Fe-Co-B is a promising system for permanent magnets. A high-throughput screening method combining diffusion couples, key alloys, Scanning Electron Microscope/Wavelength Dispersive X-ray Spectroscope (SEM/WDS), and Magnetic Force Microscope (MFM) is used in this research to understand the phase equilibria and to explore promising magnetic phases in this system. Three magnetic phases were detected and their homogeneity ranges were determined at 900 °C, which were presented by the formulae: Ce2Fe14−xCoxB (0 ≤ x ≤ 4.76), CeCo4−xFexB (0 ≤ x ≤ 3.18), and Ce3Co11−x FexB4 (0 ≤ x ≤ 6.66). The phase relations among the magnetic phases in this system have been studied. Ce2(Fe, Co)14B appears to have stronger magnetization than Ce(Co, Fe)4B and Ce3(Co, Fe)11B4 from MFM analysis when comparing the magnetic interactions of selected key alloys. Also, a non-magnetic CeCo12−xFexB6 (0 ≤ x ≤ 8.74) phase was detected in this system. A boron-rich solid solution with Ce13FexCoyB45 (32 ≤ x ≤ 39, 3 ≤ y ≤ 10) chemical composition was also observed. However, the crystal structure of this phase could not be found in the literature. Moreover, ternary solid solutions ε1 (Ce2Fe17−xCox (0 ≤ x ≤ 12.35)) and ε2 (Ce2Co17−xFex (0 ≤ x ≤ 3.57)) were found to form between Ce2Fe17 and Ce2Co17 in the Ce-Fe-Co ternary system at 900 °C. PMID:28772374

A CFD model for biomass combustion in a packed bed furnace

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

Karim, Md. Rezwanul; Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704; Ovi, Ifat Rabbil Qudrat

Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is themore » most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solid and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.« less

Properties of iron alloys under the Earth's core conditions

NASA Astrophysics Data System (ADS)

Morard, Guillaume; Andrault, Denis; Antonangeli, Daniele; Bouchet, Johann

2014-05-01

The Earth's core is constituted of iron and nickel alloyed with lighter elements. In view of their affinity with the metallic phase, their relative high abundance in the solar system and their moderate volatility, a list of potential light elements have been established, including sulfur, silicon and oxygen. We will review the effects of these elements on different aspects of Fe-X high pressure phase diagrams under Earth's core conditions, such as melting temperature depression, solid-liquid partitioning during crystallization, and crystalline structure of the solid phases. Once extrapolated to the inner-outer core boundary, these petrological properties can be used to constrain the Earth's core properties.

Calculation of Gallium-metal-Arsenic phase diagrams

NASA Technical Reports Server (NTRS)

Scofield, J. D.; Davison, J. E.; Ray, A. E.; Smith, S. R.

1991-01-01

Electrical contacts and metallization to GaAs solar cells must survive at high temperatures for several minutes under specific mission scenarios. The determination of which metallizations or alloy systems that are able to withstand extreme thermal excursions with minimum degradation to solar cell performance can be predicted by properly calculated temperature constitution phase diagrams. A method for calculating a ternary diagram and its three constituent binary phase diagrams is briefly outlined and ternary phase diagrams for three Ga-As-X alloy systems are presented. Free energy functions of the liquid and solid phase are approximated by the regular solution theory. Phase diagrams calculated using this method are presented for the Ga-As-Ge and Ga-As-Ag systems.

Thermodynamic curvature for attractive and repulsive intermolecular forces

NASA Astrophysics Data System (ADS)

May, Helge-Otmar; Mausbach, Peter; Ruppeiner, George

2013-09-01

The thermodynamic curvature scalar R for the Lennard-Jones system is evaluated in phase space, including vapor, liquid, and solid state. We paid special attention to the investigation of R along vapor-liquid, liquid-solid, and vapor-solid equilibria. Because R is a measure of interaction strength, we traced out the line R=0 dividing the phase space into regions with effectively attractive (R<0) or repulsive (R>0) interactions. Furthermore, we analyzed the dependence of R on the strength of attraction applying a perturbation ansatz proposed by Weeks-Chandler-Anderson. Our results show clearly a transition from R>0 (for poorly repulsive interaction) to R<0 when loading attraction in the intermolecular potential.

Optical constants of liquid and solid methane

NASA Technical Reports Server (NTRS)

Martonchik, John V.; Orton, Glenn S.

1994-01-01

The optical constants n(sub r) + in(sub i) of liquid methane and phase 1 solid methane were determined over the entire spectral range by the use of various data sources published in the literature. Kramers-Kronig analyses were performed on the absorption spectra of liquid methane at the boiling point (111 K) and the melting point (90 K) and on the absorption spectra of phase 1 solid methane at the melting point and at 30 K. Measurements of the static dielectric constant at these temperatures and refractive indices determined over limited spectral ranges were used as constraints in the analyses. Applications of methane optical properties to studies of outer solar system bodies are described.

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

Two-phase anaerobic digestion within a solid waste/wastewater integrated management system

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

De Gioannis, G.; Diaz, L.F.; Muntoni, A.

2008-07-01

A two-phase, wet anaerobic digestion process was tested at laboratory scale using mechanically pre-treated municipal solid waste (MSW) as the substrate. The proposed process scheme differs from others due to the integration of the MSW and wastewater treatment cycles, which makes it possible to avoid the recirculation of process effluent. The results obtained show that the supplying of facultative biomass, drawn from the wastewater aeration tank, to the solid waste acidogenic reactor allows an improvement of the performance of the first phase of the process which is positively reflected on the second one. The proposed process performed successfully, adopting mesophilicmore » conditions and a relatively short hydraulic retention time in the methanogenic reactor, as well as high values of organic loading rate. Significant VS removal efficiency and biogas production were achieved. Moreover, the methanogenic reactor quickly reached optimal conditions for a stable methanogenic phase. Studies conducted elsewhere also confirm the feasibility of integrating the treatment of the organic fraction of MSW with that of wastewater.« less

Phase equilibria and crystal chemistry of the CaO–½Sm 2O 3–CoOz system at 885 °C in air

DOE PAGES

Wong-Ng, W.; Laws, W.; Lapidus, S. H.; ...

2015-06-27

The CaO–½Sm 2O 3–CoOz system prepared at 885 °C in air consists of two calcium cobaltate compounds, namely, the 2D thermoelectric oxide solid solution, (Ca 3$-$xSm x)Co 4O 9$-$z (0 ≤ x ≤ 0.5) which has a misfit layered structure, and the 1D Ca 3Co 2O 6 which consists of chains of alternating CoO 6 trigonal prisms and CoO 6 octahedra. Ca 3Co 2O 6 was found to be a point compound without the substitution of Sm on the Ca site. A solid solution region of distorted perovskite, (Sm 1$-$xCa x)CoO 3$-$z (0 ≤ x ≤ 0.22, space group Pnma)more » was established. The reported Sm 2CoO 4 phase was not observed at 885 °C, but a ternary Ca-doped oxide, (Sm 1+xCa 1$-$x)CoO 4$-$z (Bmab) where 0 < x ≤ 0.15 was found to be stable at this temperature. In the peripheral binary systems, Sm was not present in the Ca site of CaO, while a small solid solution region was identified for (Sm 1$-$xCa x)O(3 $-$z)/2 (0 ≤ x ≤ 0.075). Lastly, ten solid solution tie-line regions and six three-phase regions were determined in the CaO–½Sm 2O 3–CoO z system in air.« less

Nitrification Processes, Conversion Kinetics, Physical Substrate Preferences and Source Function Analysis for an Aquatic Nitrification Model System

NASA Astrophysics Data System (ADS)

Zimmer, J.; O'Connor, B.; Halmo, K.; Xiong, A.

2016-02-01

Nitrification is one of the processes that prevents accumulation of ammonium in aerobic near-bottom water of almost any basin-type ecosystem. Ammonium arises in part from digestive excretion as well as decomposition and diagenesis of organic matter. Ammonium inputs are especially pronounced near abundant benthic invertebrate communities (e.g., mussel or oyster beds) and where fish congregate en masse. Recent basin-scale changes in ecology of Lake Michigan have resulted in several zones of high excretion that are not accompanied by ammonium accumulation. A roller-bottle simulation of the sediment-water interface, using sand as the solid phase, is used with natural enrichments of nitrifier communities to measure empirical values for key terms in a mathematical model to describe the N-cycle process components of our closed model system. The maximum velocity of transformation is directly proportional to solid phase material in a mature system, with half-saturation values for ammonium and nitrite transformation of 207.3 and 10.8 µM respectively. These are significantly higher than ambient concentrations of 2-5 and 0.2-1.0 µM respectively for dense invertebrate communities but in line with observed values for dense fish aggregations. Thus regulation of reduced nitrogenous compounds can be very effective in these communities when there is sufficient interaction of the solid substrate with the source water. Further analysis of rate parameters and controls in the model system, and assessment of different natural and artificial solid phases for biofilm establishment and nitrification parameters is underway.

Microstructure Formations in the Two-Phase Region of the Binary Peritectic Organic System TRIS-NPG

NASA Technical Reports Server (NTRS)

Mogeritsch, Johann; Ludwig, Andreas

2012-01-01

In order to prepare for an onboard experiment on the International Space Station (ISS), systematic directional solidification experiments with transparent hypoperitectic alloys were carried out at different solidification rates around the critical velocity for morphological stability of both solid phases. The investigations were done in the peritectic region of the binary transparent organic TRIS-NPG system where the formation of layered structures is expected to occur. The transparent appearance of the liquid and solid phase enables real time observations of the dynamic of pattern formation during solidification. The investigations show that frequently occurring nucleation events govern the peritectic solidification morphology which occurs at the limit of morphological stability. As a consequence, banded structures lead to coupled growth even if the lateral growth is much faster compared to the growth in pulling direction.

Electrochemical detection of Piscirickettsia salmonis genomic DNA from salmon samples using solid-phase recombinase polymerase amplification.

PubMed

Del Río, Jonathan Sabaté; Svobodova, Marketa; Bustos, Paulina; Conejeros, Pablo; O'Sullivan, Ciara K

2016-12-01

Electrochemical detection of solid-phase isothermal recombinase polymerase amplification (RPA) of Piscirickettsia salmonis in salmon genomic DNA is reported. The electrochemical biosensor was constructed by surface functionalization of gold electrodes with a thiolated forward primer specific to the genomic region of interest. Solid-phase RPA and primer elongation were achieved in the presence of the specific target sequence and biotinylated reverse primers. The formation of the subsequent surface-tethered duplex amplicons was electrochemically monitored via addition of streptavidin-linked HRP upon completion of solid-phase RPA. Successful quantitative amplification and detection were achieved in less than 1 h at 37 °C, calibrating with PCR-amplified genomic DNA standards and achieving a limit of detection of 5 · 10 -8  μg ml -1 (3 · 10 3 copies in 10 μl). The presented system was applied to the analysis of eight real salmon samples, and the method was also compared to qPCR analysis, observing an excellent degree of correlation. Graphical abstract Schematic of use of electrochemical RPA for detection of Psiricketessia salmonis in salmon liver.

Buckling failure of square ice-nanotube arrays constrained in graphene nanocapillaries

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

Zhu, YinBo; Wang, FengChao, E-mail: wangfc@ustc.edu.cn; Wu, HengAn

Graphene confinement provides a new physical and mechanical environment with ultrahigh van der Waals pressure, resulting in new quasi-two-dimensional phases of few-layer ice. Polymorphic transition can occur in bilayer constrained water/ice system. Here, we perform a comprehensive study of the phase transition of AA-stacked bilayer water constrained within a graphene nanocapillary. The compression-limit and superheating-limit (phase) diagrams are obtained, based on the extensive molecular-dynamics simulations at numerous thermodynamic states. Liquid-to-solid, solid-to-solid, and solid-to-liquid-to-solid phase transitions are observed in the compression and superheating of bilayer water. Interestingly, there is a temperature threshold (∼275 K) in the compression-limit diagram, which indicates thatmore » the first-order and continuous-like phase transitions of bilayer water depend on the temperature. Two obviously different physical processes, compression and superheating, display similar structural evolution; that is, square ice-nanotube arrays (BL-VHDI) will bend first and then transform into bilayer triangular AA stacking ice (BL-AAI). The superheating limit of BL-VHDI exhibits local maxima, while that of BL-AAI increases monotonically. More importantly, from a mechanics point of view, we propose a novel mechanism of the transformation from BL-VHDI to BL-AAI, both for the compression and superheating limits. This structural transformation can be regarded as the “buckling failure” of the square-ice-nanotube columns, which is dominated by the lateral pressure.« less

Rare earth indates (RE: La-Yb): influence of the synthesis route and heat treatment on the crystal structure.

PubMed

Shukla, Rakesh; Grover, Vinita; Srinivasu, Kancharlapalli; Paul, Barnita; Roy, Anushree; Gupta, Ruma; Tyagi, Avesh Kumar

2018-05-15

Rare earth indates are an interesting class of compounds with rich crystallography. The present study explores the crystallographic phases observed in REInO3 (RE: La-Yb) systems and their dependence on synthesis routes and annealing temperature. All REInO3 compositions were synthesized by a solid state route as well as gel-combustion synthesis (GC) followed by annealing at different temperatures. The systems were well characterized by powder XRD studies and were analysed by Rietveld refinement for the structural parameters. The cell parameters were observed to decrease in accordance with the trend in ionic radii on proceeding from lighter to heavier rare earth ions. Interestingly, the synthesis route and the annealing temperature had a profound bearing on the phase relationships observed in the REInO3 series. The solid state synthesized samples depicted an orthorhombic phase (Pbnm) field for LaInO3 to SmInO3, followed by a hexagonal-type phase (P63cm) for GdInO3 to DyInO3. However, the phase field distribution was greatly influenced upon employing gel-combustion (GC) wherein both single-phasic hexagonal and orthorhombic phase fields were found to shrink. Annealing the GC-synthesized compositions to still higher temperatures (1250 °C) further evolved the phase boundaries. An important outcome of the study is observance of polymorphism in SmInO3 which crystallized in the hexagonal phase when synthesized by GC and orthorhombic phase by solid state synthesis. This reveals the all-important role played by synthesis conditions. The existence and energetics of the two polymorphs have been elucidated and discussed with the aid of theoretical studies.

Replacement of Ablators with Phase-Change Material for Thermal Protection of STS Elements

NASA Technical Reports Server (NTRS)

Kaul, Raj K.; Stuckey, Irvin; Munafo, Paul M. (Technical Monitor)

2002-01-01

As part of the research and development program to develop new Thermal Protection System (TPS) materials for aerospace applications at NASA's Marshall Space Flight Center (MSFC), an experimental study was conducted on a new concept for a non-ablative TPS material. Potential loss of TPS material and ablation by-products from the External Tank (ET) or Solid Rocket Booster (SRB) during Shuttle flight with the related Orbiter tile damage necessitates development of a non-ablative thermal protection system. The new Thermal Management Coating (TMC) consists of phase-change material encapsulated in micro spheres and a two-part resin system to adhere the coating to the structure material. The TMC uses a phase-change material to dissipate the heat produced during supersonic flight rather than an ablative material. This new material absorbs energy as it goes through a phase change during the heating portion of the flight profile and then the energy is slowly released as the phase-change material cools and returns to its solid state inside the micro spheres. The coating was subjected to different test conditions simulating design flight environments at the NASA/MSFC Improved Hot Gas Facility (IHGF) to study its performance.

Vapor-phase infrared spectroscopy on solid organic compounds with a pulsed resonant photoacoustic detection scheme

NASA Astrophysics Data System (ADS)

Bartlome, Richard; Fischer, Cornelia; Sigrist, Markus W.

2005-08-01

There is a great need for a low cost and sensitive method to measure infrared spectra of solid organic compounds in the gas phase. To record such spectra, we propose an optical parametric generator-based photoacoustic spectrometer, which emits in the mid-infrared fingerprint region between 3 and 4 microns. In this system, the sample is heated in a vessel before entering a home built photoacoustic cell, where the gaseous molecules are excited by a tunable laser source with a frequency repetition rate that matches the first longitudinal resonance frequency of the photocaoustic cell. In a first phase, we have focused on low-melting point stimulants such as Nikethamide, Mephentermine sulfate, Methylephedrine, Ephedrine and Pseudoephedrine. The vapor-phase spectra of these doping substances were measured between 2800 and 3100 cm-1, where fundamental C-H stretching vibrations take place. Our spectra show notable differences with commercially available condensed phase spectra. Our scheme enables to measure very low vapor pressures of low-melting point (<160 °C) solid organic compounds. Furthermore, the optical resolution of 8 cm-1 is good enough to distinguish closely related chemical structures such as the Ephedra alkaloids Ephedrine and Methylephedrine, but doesn't allow to differentiate diastereoisomeric pairs such as Ephedrine and Pseudoephedrine, two important neurotransmitters which reveal different biological activities. Therefore, higher resolution and a system capable of measuring organic compounds with higher melting points are required.

Mesoscopic structural phase progression in photo-excited VO 2 revealed by time-resolved x-ray diffraction microscopy

DOE PAGES

Zhu, Yi; Cai, Zhonghou; Chen, Pice; ...

2016-02-26

Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase seperated regions. The ability to simultanousely track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of- the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO 2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation ismore » initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO 2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, which is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO 2. Lastly, the direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.« less

Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

NASA Astrophysics Data System (ADS)

Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, Il Woong; Walko, Donald A.; Dufresne, Eric M.; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

2016-02-01

Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy.

PubMed

Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J; Jung, Il Woong; Walko, Donald A; Dufresne, Eric M; Jeong, Jaewoo; Samant, Mahesh G; Parkin, Stuart S P; Freeland, John W; Evans, Paul G; Wen, Haidan

2016-02-26

Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

Interfacial Tension in the CaO-Al2O3-SiO2-(MgO) Liquid Slag-Solid Oxide Systems

NASA Astrophysics Data System (ADS)

Abdeyazdan, Hamed; Monaghan, Brian J.; Longbottom, Raymond J.; Rhamdhani, M. Akbar; Dogan, Neslihan; Chapman, Michael W.

2017-08-01

Interfacial phenomenon is critical in metal processing and refining. While it is known to be important, there are little data available for key oxide systems in the literature. In this study, the interfacial tension ( σ LS) of liquid slag on solid oxides (alumina, spinel, and calcium aluminate), for a range of slags in the CaO-Al2O3-SiO2-(MgO) system at 1773 K (1500 °C), has been evaluated. The results show that basic ladle-type slags exhibit lower σ LS with oxide phases examined compared to that of acid tundish-type slags. Also, within the slag types (acid and base), σ LS was observed to decrease with increasing slag basicity. A correlation between σ LS and slag structure was observed, i.e., σ LS was found to decrease linearly with increasing of slag optical basicity (Λ) and decrease logarithmically with decreasing of slag viscosity from acid to base slags. This indicated a higher σ LS as the ions in the slag become larger and more complex. Through a work of adhesion ( W) analysis, it was shown that basic ladle slags with lower σ LS result in a greater W, i.e., form a stronger bond with the solid oxide phases examined. This indicates that all other factors being equal, the efficiency of inclusion removal from steel of inclusions of similar phase to these solid oxides would be greater.

Hydrodynamic Stability Analysis of Particle-Laden Solid Rocket Motors

NASA Astrophysics Data System (ADS)

Elliott, T. S.; Majdalani, J.

2014-11-01

Fluid-wall interactions within solid rocket motors can result in parietal vortex shedding giving rise to hydrodynamic instabilities, or unsteady waves, that translate into pressure oscillations. The oscillations can result in vibrations observed by the rocket, rocket subsystems, or payload, which can lead to changes in flight characteristics, design failure, or other undesirable effects. For many years particles have been embedded in solid rocket propellants with the understanding that their presence increases specific impulse and suppresses fluctuations in the flowfield. This study utilizes a two dimensional framework to understand and quantify the aforementioned two-phase flowfield inside a motor case with a cylindrical grain perforation. This is accomplished through the use of linearized Navier-Stokes equations with the Stokes drag equation and application of the biglobal ansatz. Obtaining the biglobal equations for analysis requires quantification of the mean flowfield within the solid rocket motor. To that end, the extended Taylor-Culick form will be utilized to represent the gaseous phase of the mean flowfield while the self-similar form will be employed for the particle phase. Advancing the mean flowfield by quantifying the particle mass concentration with a semi-analytical solution the finalized mean flowfield is combined with the biglobal equations resulting in a system of eight partial differential equations. This system is solved using an eigensolver within the framework yielding the entire spectrum of eigenvalues, frequency and growth rate components, at once. This work will detail the parametric analysis performed to demonstrate the stabilizing and destabilizing effects of particles within solid rocket combustion.

40 CFR 227.32 - Liquid, suspended particulate, and solid phases of a material.

Code of Federal Regulations, 2010 CFR

2010-07-01

... solid phases of a material. 227.32 Section 227.32 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS Definitions § 227.32 Liquid, suspended particulate, and solid phases of a material. (a) For the... obtained above prior to centrifugation and filtration. The solid phase includes all material settling to...

40 CFR 227.32 - Liquid, suspended particulate, and solid phases of a material.

Code of Federal Regulations, 2011 CFR

2011-07-01

... solid phases of a material. 227.32 Section 227.32 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS Definitions § 227.32 Liquid, suspended particulate, and solid phases of a material. (a) For the... obtained above prior to centrifugation and filtration. The solid phase includes all material settling to...

DNA extraction on bio-chip: history and preeminence over conventional and solid-phase extraction methods.

PubMed

Ayoib, Adilah; Hashim, Uda; Gopinath, Subash C B; Md Arshad, M K

2017-11-01

This review covers a developmental progression on early to modern taxonomy at cellular level following the advent of electron microscopy and the advancement in deoxyribonucleic acid (DNA) extraction for expatiation of biological classification at DNA level. Here, we discuss the fundamental values of conventional chemical methods of DNA extraction using liquid/liquid extraction (LLE) followed by development of solid-phase extraction (SPE) methods, as well as recent advances in microfluidics device-based system for DNA extraction on-chip. We also discuss the importance of DNA extraction as well as the advantages over conventional chemical methods, and how Lab-on-a-Chip (LOC) system plays a crucial role for the future achievements.

Structure Evolution and Reactivity of the Sc(2- x)V xO3+δ (0 ≤ x ≤ 2.0) System.

PubMed

Lussier, Joey A; Simon, Fabian J; Whitfield, Pamela S; Singh, Kalpana; Thangadurai, Venkataraman; Bieringer, Mario

2018-05-07

Solid oxide fuel cells (SOFCs) are solid-state electrochemical devices that directly convert chemical energy of fuels into electricity with high efficiency. Because of their fuel flexibility, low emissions, high conversion efficiency, no moving parts, and quiet operation, they are considered as a promising energy conversion technology for low carbon future needs. Solid-state oxide and proton conducting electrolytes play a crucial role in improving the performance and market acceptability of SOFCs. Defect fluorite phases are some of the most promising fast oxide ion conductors for use as electrolytes in SOFCs. We report the synthesis, structure, phase diagram, and high-temperature reactivity of the Sc (2- x) V x O 3+δ (0 ≤ x ≤ 2.00) oxide defect model system. For all Sc (2- x) V x O 3.0 phases with x ≤ 1.08 phase-pure bixbyite-type structures are found, whereas for x ≥ 1.68 phase-pure corundum structures are reported, with a miscibility gap found for 1.08 < x < 1.68. Structural details obtained from the simultaneous Rietveld refinements using powder neutron and X-ray diffraction data are reported for the bixbyite phases, demonstrating a slight V 3+ preference toward the 8b site. In situ X-ray diffraction experiments were used to explore the oxidation of the Sc (2- x) V x O 3.0 phases. In all cases ScVO 4 was found as a final product, accompanied by Sc 2 O 3 for x < 1.0 and V 2 O 5 when x > 1.0; however, the oxidative pathway varied greatly throughout the series. Comments are made on different synthesis strategies, including the effect on crystallinity, reaction times, rate-limiting steps, and reaction pathways. This work provides insight into the mechanisms of solid-state reactions and strategic guidelines for targeted materials synthesis.

Finite element methods for the biomechanics of soft hydrated tissues: nonlinear analysis and adaptive control of meshes.

PubMed

Spilker, R L; de Almeida, E S; Donzelli, P S

1992-01-01

This chapter addresses computationally demanding numerical formulations in the biomechanics of soft tissues. The theory of mixtures can be used to represent soft hydrated tissues in the human musculoskeletal system as a two-phase continuum consisting of an incompressible solid phase (collagen and proteoglycan) and an incompressible fluid phase (interstitial water). We first consider the finite deformation of soft hydrated tissues in which the solid phase is represented as hyperelastic. A finite element formulation of the governing nonlinear biphasic equations is presented based on a mixed-penalty approach and derived using the weighted residual method. Fluid and solid phase deformation, velocity, and pressure are interpolated within each element, and the pressure variables within each element are eliminated at the element level. A system of nonlinear, first-order differential equations in the fluid and solid phase deformation and velocity is obtained. In order to solve these equations, the contributions of the hyperelastic solid phase are incrementally linearized, a finite difference rule is introduced for temporal discretization, and an iterative scheme is adopted to achieve equilibrium at the end of each time increment. We demonstrate the accuracy and adequacy of the procedure using a six-node, isoparametric axisymmetric element, and we present an example problem for which independent numerical solution is available. Next, we present an automated, adaptive environment for the simulation of soft tissue continua in which the finite element analysis is coupled with automatic mesh generation, error indicators, and projection methods. Mesh generation and updating, including both refinement and coarsening, for the two-dimensional examples examined in this study are performed using the finite quadtree approach. The adaptive analysis is based on an error indicator which is the L2 norm of the difference between the finite element solution and a projected finite element solution. Total stress, calculated as the sum of the solid and fluid phase stresses, is used in the error indicator. To allow the finite difference algorithm to proceed in time using an updated mesh, solution values must be transferred to the new nodal locations. This rezoning is accomplished using a projected field for the primary variables. The accuracy and effectiveness of this adaptive finite element analysis is demonstrated using a linear, two-dimensional, axisymmetric problem corresponding to the indentation of a thin sheet of soft tissue. The method is shown to effectively capture the steep gradients and to produce solutions in good agreement with independent, converged, numerical solutions.

Gibbs Energy Modeling of Digenite and Adjacent Solid-State Phases

NASA Astrophysics Data System (ADS)

Waldner, Peter

2017-08-01

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

DNA purification by triplex-affinity capture and affinity capture electrophoresis

DOEpatents

Cantor, C.R.; Ito, Takashi; Smith, C.L.

1996-01-09

The invention provides a method for purifying or isolating double stranded DNA intact using triple helix formation. The method includes the steps of complexing an oligonucleotide and double stranded DNA to generate a triple helix and immobilization of the triple helix on a solid phase by means of a molecular recognition system such as avidin/biotin. The purified DNA is then recovered intact by treating the solid phase with a reagent that breaks the bonds between the oligonucleotide and the intact double stranded DNA while not affecting the Watson-Crick base pairs of the double helix. The present invention also provides a method for purifying or isolating double stranded DNA intact by complexing the double stranded DNA with a specific binding partner and recovering the complex during electrophoresis by immobilizing it on a solid phase trap imbedded in an electrophoretic gel. 6 figs.

Coupling microscopic and mesoscopic scales to simulate chemical equilibrium between a nanometric carbon cluster and detonation products fluid.

PubMed

Bourasseau, Emeric; Maillet, Jean-Bernard

2011-04-21

This paper presents a new method to obtain chemical equilibrium properties of detonation products mixtures including a solid carbon phase. In this work, the solid phase is modelled through a mesoparticle immersed in the fluid, such that the heterogeneous character of the mixture is explicitly taken into account. Inner properties of the clusters are taken from an equation of state obtained in a previous work, and interaction potential between the nanocluster and the fluid particles is derived from all-atoms simulations using the LCBOPII potential (Long range Carbon Bond Order Potential II). It appears that differences in chemical equilibrium results obtained with this method and the "composite ensemble method" (A. Hervouet et al., J. Phys. Chem. B, 2008, 112.), where fluid and solid phases are considered as non-interacting, are not significant, underlining the fact that considering the inhomogeneity of such system is crucial.

Conformational polymorphism and thermochemical analysis of 5,5' ''-bis[(2,2,5,5-tetramethyl-1-aza-2,5-disila-1-cyclopentyl)ethyl]-2,2':5',2' ':5' ',2' ''-quaterthiophene.

PubMed

Muguruma, Hitoshi; Hotta, Shu

2006-11-23

The titled compound exists as two polymorphic solid phases (denoted form-I and form-II). Form-I obtained by as-synthesized material is a more stable phase. Form-II is a less stable phase. Spontaneous solid-solid transformation from form-II to form-I is observed in the temperature range between room temperature and the melting point of form-I (Tm = 156.5 degrees C), and its activation energy is estimated to be 96 kJ mol-1 by Arrhenius plot. The solid-solute-solid transformation (recrystallization from solution) from form-II to form-I is also observed. In contrast, form-II is obtained only by a solid-melt-solid transformation from form-I. Therefore, the system of two polymorphs is monotropic. The solid-state NMR measurement shows that form-I has the molecular conformation of complete S-syn-anti-syn in the oligothiophene backbone, whereas form-II has that of S-all-anti. With the solution NMR data, the polymorphism could not be observed. Therefore, the polymorphs originate from the different molecular packing involving the conformational change of the molecule. This unique property is attributed to the extra bulky terminal groups of the compounds. However, despite the extra bulky terminal groups, the mentioned polymorphism is not observed in the titled compound analogue which has S-all-anti conformation (like form-II).

Fuel-Flexible Gasification-Combustion Technology for Production of H2 and Sequestration-Ready CO2

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

Parag Kulkarni; Jie Guan; Raul Subia

In the near future, the nation will continue to rely on fossil fuels for electricity, transportation, and chemicals. It is necessary to improve both the process efficiency and environmental impact of fossil fuel utilization including greenhouse gas management. GE Global Research (GEGR) investigated an innovative fuel-flexible Unmixed Fuel Processor (UFP) technology with potential to produce H{sub 2}, power, and sequestration-ready CO{sub 2} from coal and other solid fuels. The UFP technology offers the long-term potential for reduced cost, increased process efficiency relative to conventional gasification and combustion systems, and near-zero pollutant emissions. GE was awarded a contract from U.S. DOEmore » NETL to investigate and develop the UFP technology. Work started on the Phase I program in October 2000 and on the Phase II effort in April 2005. In the UFP technology, coal, water and air are simultaneously converted into (1) hydrogen rich stream that can be utilized in fuel cells or turbines, (2) CO{sub 2} rich stream for sequestration, and (3) high temperature/pressure vitiated air stream to produce electricity in a gas turbine expander. The process produces near-zero emissions with an estimated efficiency higher than Integrated Gasification Combined Cycle (IGCC) process with conventional CO{sub 2} separation. The Phase I R&D program established the chemical feasibility of the major reactions of the integrated UFP technology through lab-, bench- and pilot-scale testing. A risk analysis session was carried out at the end of Phase I effort to identify the major risks in the UFP technology and a plan was developed to mitigate these risks in the Phase II of the program. The Phase II effort focused on three high-risk areas: economics, lifetime of solids used in the UFP process, and product gas quality for turbines (or the impact of impurities in the coal on the overall system). The economic analysis included estimating the capital cost as well as the costs of hydrogen and electricity for a full-scale UFP plant. These costs were benchmarked with IGCC polygen plants with similar level of CO{sub 2} capture. Based on the promising economic analysis comparison results (performed with the help from Worley Parsons), GE recommended a 'Go' decision in April 2006 to continue the experimental investigation of the UFP technology to address the remaining risks i.e. solids lifetime and the impact of impurities in the coal on overall system. Solids attrition and lifetime risk was addressed via bench-scale experiments that monitor solids performance over time and by assessing materials interactions at operating conditions. The product gas under the third reactor (high-temperature vitiated air) operating conditions was evaluated to assess the concentration of particulates, pollutants and other impurities relative to the specifications required for gas turbine feed streams. During this investigation, agglomeration of solids used in the UFP process was identified as a serious risk that impacts the lifetime of the solids and in turn feasibility of the UFP technology. The main causes of the solids agglomeration were the combination of oxygen transfer material (OTM) reduction at temperatures {approx}1000 C and interaction between OTM and CO{sub 2} absorbing material (CAM) at high operating temperatures (>1200 C). At the end of phase II, in March 2008, GEGR recommended a 'No-go' decision for taking the UFP technology to the next level of development, i.e. development of a 3-5 MW prototype system, at this time. GEGR further recommended focused materials development research programs on improving the performance and lifetime of solids materials used in UFP or chemical looping technologies. The scale-up activities would be recommended only after mitigating the risks involved with the agglomeration and overall lifetime of the solids. This is the final report for the phase II of the DOE-funded Vision 21 program entitled 'Fuel-Flexible Gasification-Combustion Technology for Production of H{sub 2} and Sequestration-Ready CO{sub 2}' (DOE Award No. DE-FC26-00NT40974). The report focuses on the major accomplishments and lessons learned in analyzing the risks of the novel UFP technology during Phase II of the DOE program.« less

Modified anaerobic digestion elutriated phased treatment for the anaerobic co-digestion of sewage sludge and food wastewater.

PubMed

Mo, Kyung; Lee, Wonbae; Kim, Moonil

2017-02-01

A modified anaerobic digestion elutriated phased treatment (MADEPT) process was developed for investigating anaerobic co-digestion of sewage sludge and food wastewater. The anaerobic digestion elutriated phased treatment (ADEPT) process is similar to a two-phase system, however, in which the effluent from a methanogenic reactor recycles into an acidogenic reactor to elutriate mainly dissolved organics. Although ADEPT could reduce reactor volume significantly, the unsolubilized solids should be wasted from the system. The MADEPT process combines thermo-alkali solubilization with ADEPT to improve anaerobic performance and to minimize the sludge disposal. It was determined that the optimal volume mixing ratio of sewage sludge and food wastewater was 4 : 1 for the anaerobic co-digestion. The removal efficiencies of total chemical oxygen demand, volatile solids, and volatile suspended solids in the MADEPT process were 73%, 70%, and 64%, respectively. However, those in the ADEPT process were only 48%, 37%, and 40%, respectively, at the same hydraulic retention time (HRT) of 7 days. The gas production of MADEPT was two times higher than that of ADEPT. The thermo-alkali solubilization increased the concentration of dissolved organics so that they could be effectively degraded in a short HRT, implying that MADEPT could improve the performance of ADEPT in anaerobic co-digestion.

Automated microfluidic devices integrating solid-phase extraction, fluorescent labeling, and microchip electrophoresis for preterm birth biomarker analysis.

PubMed

Sahore, Vishal; Sonker, Mukul; Nielsen, Anna V; Knob, Radim; Kumar, Suresh; Woolley, Adam T

2018-01-01

We have developed multichannel integrated microfluidic devices for automated preconcentration, labeling, purification, and separation of preterm birth (PTB) biomarkers. We fabricated multilayer poly(dimethylsiloxane)-cyclic olefin copolymer (PDMS-COC) devices that perform solid-phase extraction (SPE) and microchip electrophoresis (μCE) for automated PTB biomarker analysis. The PDMS control layer had a peristaltic pump and pneumatic valves for flow control, while the PDMS fluidic layer had five input reservoirs connected to microchannels and a μCE system. The COC layers had a reversed-phase octyl methacrylate porous polymer monolith for SPE and fluorescent labeling of PTB biomarkers. We determined μCE conditions for two PTB biomarkers, ferritin (Fer) and corticotropin-releasing factor (CRF). We used these integrated microfluidic devices to preconcentrate and purify off-chip-labeled Fer and CRF in an automated fashion. Finally, we performed a fully automated on-chip analysis of unlabeled PTB biomarkers, involving SPE, labeling, and μCE separation with 1 h total analysis time. These integrated systems have strong potential to be combined with upstream immunoaffinity extraction, offering a compact sample-to-answer biomarker analysis platform. Graphical abstract Pressure-actuated integrated microfluidic devices have been developed for automated solid-phase extraction, fluorescent labeling, and microchip electrophoresis of preterm birth biomarkers.

Determination of pesticides in waters by automatic on-line solid-phase extraction-capillary electrophoresis.

PubMed

Hinsmann, P; Arce, L; Ríos, A; Valcárcel, M

2000-01-07

The separation of seven pesticides by micellar electrokinetic capillary chromatography in spiked water samples is described, allowing the analysis of pesticides mixtures down to a concentration of 50 microg l(-1) in less than 13 min. Calibration, pre-concentration, elution and injection into the sample vial was carried out automatically by a continuous flow system (CFS) coupled to a capillary electrophoresis system via a programmable arm. The whole system was electronically coupled by a micro-processor and completely controlled by a computer. A C18 solid-phase mini-column was used for the pre-concentration, allowing a 12-fold enrichment (as an average value) of the pesticides from fortified water samples. Under the optimal extraction conditions, recoveries between 90 and 114% for most of the pesticides were obtained.

Using Peltier Cells to Study Solid-Liquid-Vapour Transitions and Supercooling

ERIC Educational Resources Information Center

Torzo, Giacomo; Soletta, Isabella; Branca, Mario

2007-01-01

We propose an apparatus for teaching experimental thermodynamics in undergraduate introductory courses, using thermoelectric modules and a real-time data acquisition system. The device may be made at low cost, still providing an easy approach to the investigation of liquid-solid and liquid-vapour phase transitions and of metastable states…

Interface-Driven Phenomena in Solids: Thermodynamics, Kinetics and Chemistry

DOE PAGES

Abdeljawad, Fadi; Foiles, Stephen M.

2016-05-04

The study of materials interfaces dates back over a century. In solid systems and from an engineering perspective, free surfaces and internal (grain and/or phase) boundaries influence a wide range of properties, such as thermal, electrical and optical transport, and mechanical ones. The properties and the role of interfaces has been discussed extensively in various reviews such as by Sutton and Balluffi. As the characteristic feature size of a materials system (i.e., grain size) is decreased to the nanometer scale, interface-driven physics is expected to dominate due to the increased density of such planar defects. Moreover, interfacial attributes, thermodynamics, andmore » mobility play a key role in phase transformations, such as solidification dynamics and structural transitions in solids, and in homogenization and microstructural evolution processes, such as grain growth, coarsening, and recrystallization. In summary, the set of articles published in this special topic titled: “Interface-Driven Phenomena in Solids: Thermodynamics, Kinetics and Chemistry” covers topics related to microstructure evolution, segregation/adsorption phenomena and interface interactions with other materials defects.« less

Interface-Driven Phenomena in Solids: Thermodynamics, Kinetics and Chemistry

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

Abdeljawad, Fadi; Foiles, Stephen M.

The study of materials interfaces dates back over a century. In solid systems and from an engineering perspective, free surfaces and internal (grain and/or phase) boundaries influence a wide range of properties, such as thermal, electrical and optical transport, and mechanical ones. The properties and the role of interfaces has been discussed extensively in various reviews such as by Sutton and Balluffi. As the characteristic feature size of a materials system (i.e., grain size) is decreased to the nanometer scale, interface-driven physics is expected to dominate due to the increased density of such planar defects. Moreover, interfacial attributes, thermodynamics, andmore » mobility play a key role in phase transformations, such as solidification dynamics and structural transitions in solids, and in homogenization and microstructural evolution processes, such as grain growth, coarsening, and recrystallization. In summary, the set of articles published in this special topic titled: “Interface-Driven Phenomena in Solids: Thermodynamics, Kinetics and Chemistry” covers topics related to microstructure evolution, segregation/adsorption phenomena and interface interactions with other materials defects.« less

The dressed atom as binary phase modulator: towards attojoule/edge optical phase-shift keying.

PubMed

Kerckhoff, Joseph; Armen, Michael A; Pavlichin, Dmitri S; Mabuchi, Hideo

2011-03-28

We use a single 133Cs atom strongly coupled to an optical resonator to induce random binary phase modulation of a near infra-red, ∼ 500 pW laser beam, with each modulation edge caused by the dissipation of a single photon (≈ 0.23 aJ) by the atom. While our ability to deterministically induce phase edges with an additional optical control beam is limited thus far, theoretical analysis of an analogous, solid-state system indicates that efficient external control should be achievable in demonstrated nanophotonic systems.

Solar power satellite system definition study. Volume 4: Solid State SPS Analysis, Phase 3

NASA Technical Reports Server (NTRS)

1980-01-01

A 2500 megawatt solid ground output Solar Power Satellite (SPS) of conventional configuration was designed and analyzed. Because the power per receiving antenna is halved, as compared with the klystron reference, twice the number of receiving antennas are needed to deliver the same total power. The solid state approach appears feasible with a slightly greater specific mass and slightly higher cost than the klystron SPS design.

SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOFC

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

Steven Shaffer; Sean Kelly; Subhasish Mukerjee

2003-06-09

The objective of Phase I under this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with piped-in water (Demonstration System A); and Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustionmore » engine. This technical progress report covers work performed by Delphi from July through December 2002 under Department of Energy Cooperative Agreement DE-FC-02NT41246 for the 5 kW mass-market automotive (gasoline) auxiliary power unit. This report highlights technical results of the work performed under the following tasks for the automotive 5 kW system: Task 1--System Design and Integration; Task 2--Solid Oxide Fuel Cell Stack Developments; Task 3--Reformer Developments; Task 4--Development of Balance of Plant (BOP) Components; Task 5--Manufacturing Development (Privately Funded); Task 6--System Fabrication; and Task 7--System Testing.« less

The use of solid supports to generate nucleic acid carriers.

PubMed

Unciti-Broceta, Asier; Díaz-Mochón, Juan José; Sánchez-Martín, Rosario M; Bradley, Mark

2012-07-17

Nucleic acids are the foundation stone of all cellular processes. Consequently, the use of DNA or RNA to treat genetic and acquired disorders (so called gene therapy) offers enormous potential benefits. The restitution of defective genes or the suppression of malignant genes could target a range of diseases, including cancers, inherited diseases (cystic fibrosis, muscular dystrophy, etc.), and viral infections. However, this strategy has a major barrier: the size and charge of nucleic acids largely restricts their transit into eukaryotic cells. Potential strategies to solve this problem include the use of a variety of natural and synthetic nucleic acid carriers. Driven by the aim and ambition of translating this promising therapeutic approach into the clinic, researchers have been actively developing advanced delivery systems for nucleic acids for more than 20 years. A decade ago we began our investigations of solid-phase techniques to construct families of novel nucleic acid carriers for transfection. We envisaged that the solid-phase synthesis of polycationic dendrimers and derivatized polyamimes would offer distinct advantages over solution phase techniques. Notably in solid phase synthesis we could take advantage of mass action and streamlined purification procedures, while simplifying the handling of compounds with high polarities and plurality of functional groups. Parallel synthesis methods would also allow rapid access to libraries of compounds with improved purities and yields over comparable solution methodologies and facilitate the development of structure activity relationships. We also twisted the concept of the solid-phase support on its head: we devised miniaturized solid supports that provided an innovative cell delivery vehicle in their own right, carrying covalently conjugated cargos (biomolecules) into cells. In this Account, we summarize the main outcomes of this series of chemically related projects.

Relating hydrogen-bonding interactions with the phase behavior of naproxen/PVP K 25 solid dispersions: evaluation of solution-cast and quench-cooled films.

PubMed

Paudel, Amrit; Nies, Erik; Van den Mooter, Guy

2012-11-05

In this work, we investigated the relationship between various intermolecular hydrogen-bonding (H-bonding) interactions and the miscibility of the model hydrophobic drug naproxen with the hydrophilic polymer polyvinylpyrrolidone (PVP) across an entire composition range of solid dispersions prepared by quasi-equilibrium film casting and nonequilibrium melt quench cooling. The binary phase behavior in solid dispersions exhibited substantial processing method dependence. The solid state solubility of crystalline naproxen in PVP to form amorphous solid dispersions was 35% and 70% w/w naproxen in solution-cast films and quench-cooled films, respectively. However, the presence of a single mixed phase glass transition indicated the amorphous miscibility to be 20% w/w naproxen for the films, beyond which amorphous-amorphous and/or crystalline phase separations were apparent. This was further supported by the solution state interactions data such as PVP globular size distribution and solution infrared spectral profiles. The borderline melt composition showed cooling rate dependence of amorphization. The glass transition and melting point depression profiles of the system were treated with the analytical expressions based on Flory-Huggins mixing theory to interpolate the equilibrium solid solubility. FTIR analysis and subsequent spectral deconvolution revealed composition and miscibility dependent variations in the strength of drug-polymer intermolecular H-bonding. Two types of H-bonded populations were evidenced from 25% w/w and 35% w/w naproxen in solution-cast films and quench-cooled films, respectively, with the higher fraction of strongly H-bonded population in the drug rich domains of phase separated amorphous film compositions and highly drug loaded amorphous quench-cooled dispersions.

Overview: Experimental studies of crystal nucleation: Metals and colloids.

PubMed

Herlach, Dieter M; Palberg, Thomas; Klassen, Ina; Klein, Stefan; Kobold, Raphael

2016-12-07

Crystallization is one of the most important phase transformations of first order. In the case of metals and alloys, the liquid phase is the parent phase of materials production. The conditions of the crystallization process control the as-solidified material in its chemical and physical properties. Nucleation initiates the crystallization of a liquid. It selects the crystallographic phase, stable or meta-stable. Its detailed knowledge is therefore mandatory for the design of materials. We present techniques of containerless processing for nucleation studies of metals and alloys. Experimental results demonstrate the power of these methods not only for crystal nucleation of stable solids but in particular also for investigations of crystal nucleation of metastable solids at extreme undercooling. This concerns the physical nature of heterogeneous versus homogeneous nucleation and nucleation of phases nucleated under non-equilibrium conditions. The results are analyzed within classical nucleation theory that defines the activation energy of homogeneous nucleation in terms of the interfacial energy and the difference of Gibbs free energies of solid and liquid. The interfacial energy acts as barrier for the nucleation process. Its experimental determination is difficult in the case of metals. In the second part of this work we therefore explore the potential of colloidal suspensions as model systems for the crystallization process. The nucleation process of colloids is observed in situ by optical observation and ultra-small angle X-ray diffraction using high intensity synchrotron radiation. It allows an unambiguous discrimination of homogeneous and heterogeneous nucleation as well as the determination of the interfacial free energy of the solid-liquid interface. Our results are used to construct Turnbull plots of colloids, which are discussed in relation to Turnbull plots of metals and support the hypothesis that colloids are useful model systems to investigate crystal nucleation.

Quantum melting of a two-dimensional Wigner crystal

NASA Astrophysics Data System (ADS)

Dolgopolov, V. T.

2017-10-01

The paper reviews theoretical predictions about the behavior of two-dimensional low-density electron systems at nearly absolute zero temperatures, including the formation of an electron (Wigner) crystal, crystal melting at a critical electron density, and transitions between crystal modifications in more complex (for example, two-layer) systems. The paper presents experimental results obtained from real two-dimensional systems in which the nonconducting (solid) state of the electronic system with indications of collective localization is actually realized. Experimental methods for detecting a quantum liquid-solid phase interface are discussed.

The investigation of contact line effect on nanosized droplet wetting behavior with solid temperature condition

NASA Astrophysics Data System (ADS)

Haegon, Lee; Joonsang, Lee

2017-11-01

In many multi-phase fluidic systems, there are essentially contact interfaces including liquid-vapor, liquid-solid, and solid-vapor phase. There is also a contact line where these three interfaces meet. The existence of these interfaces and contact lines has a considerable impact on the nanoscale droplet wetting behavior. However, recent studies have shown that Young's equation does not accurately represent this behavior at the nanoscale. It also emphasized the importance of the contact line effect.Therefore, We performed molecular dynamics simulation to imitate the behavior of nanoscale droplets with solid temperature condition. And we find the effect of solid temperature on the contact line motion. Furthermore, We figure out the effect of contact line force on the wetting behavior of droplet according to the different solid temperature condition. With solid temperature condition variation, the magnitude of contact line friction decreases significantly. We also divide contact line force by effect of bulk liquid, interfacial tension, and solid surface. This work was also supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (MSIP) (No. 2015R1A5A1037668) and BrainKorea21plus.

Phase diagrams and physicochemical properties of Li+,K+(Rb+)//borate-H2O systems at 323 K

NASA Astrophysics Data System (ADS)

Feng, Shan; Yu, Xudong; Cheng, Xinglong; Zeng, Ying

2017-11-01

The phase and physicochemical properties diagrams of Li+,K+(Rb+)//borate-H2O systems at 323 K were constructed using the experimentally measured solubilities, densities, and refractive indices. The Schreinemakers' wet residue method and the X-ray diffraction were used for the determination of the compositions of solid phase. Results show that these two systems belong to the hydrate I type, with no solid solution or double salt formation. The borate phases formed in our experiments are RbB5O6(OH)4 · 2H2O, Li2B4O5(OH)4 · H2O, and K2B4O5(OH)4 · 2H2O. Comparison between the stable phase diagrams of the studied system at 288, 323, and 348 K show that in this temperature range, the crystallization form of salts do not changed. With the increase in temperature, the crystallization field of Li2B4O5(OH)4 · H2O salt at 348 K is obviously larger than that at 288 K. In the Li+,K+(Rb+)//borate-H2O systems, the densities and refractive indices of the solutions (at equilibrium) increase along with the mass fraction of K2B4O7 (Rb2B4O7), and reach the maximum values at invariant point E.

DEVELOPMENT OF INTERATOMIC POTENTIALS IN TUNGSTEN-RHENIUM SYSTEMS

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

Setyawan, Wahyu; Nandipati, Giridhar; Kurtz, Richard J.

2016-09-01

Reference data are generated using the ab initio method to fit interatomic potentials for the W-Re system. The reference data include single phases of W and Re, strained structures, slabs, systems containing several concentrations of vacancies, systems containing various types of interstitial defects, melt structures, structures in the σ and χ phases, and structures containing several concentrations of solid solutions of Re in bcc W and W in hcp Re. Future work will start the fitting iterations.

Strategy for stabilization of the antiferroelectric phase (Pbma) over the metastable ferroelectric phase (P2{sub 1}ma) to establish double loop hysteresis in lead-free (1−x)NaNbO{sub 3}-xSrZrO{sub 3} solid solution

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

Guo, Hanzheng, E-mail: hug17@psu.edu; Randall, Clive A.; Shimizu, Hiroyuki

A new lead-free antiferroelectric solid solution system, (1−x)NaNbO{sub 3}-xSrZrO{sub 3}, was rationalized through noting the crystal chemistry trend, of decreasing the tolerance factor and an increase in the average electronegativity of the system. The SrZrO{sub 3} doping was found to effectively stabilize the antiferroelectric (P) phase in NaNbO{sub 3} without changing its crystal symmetry. Preliminary electron diffraction and polarization measurements were presented which verified the enhanced antiferroelectricity. In view of our recent report of another lead-free antiferroelectric system (1−x)NaNbO{sub 3}-xCaZrO{sub 3} [H. Shimizu et al. “Lead-free antiferroelectric: xCaZrO{sub 3} - (1−x)NaNbO{sub 3} system (0 ≤ x ≤ 0.10),” Dalton Trans.more » (published online)], the present results point to a general strategy of utilizing tolerance factor to develop a broad family of new lead-free antiferroelectrics with double polarization hysteresis loops. We also speculate on a broad family of possible solid solutions that could be identified and tested for this important type of dielectric.« less

Solar power satellite system definition study. Volume 2, part 3: Final briefing, 16 May 1980, phase 3

NASA Technical Reports Server (NTRS)

1980-01-01

Alternatives to the microwave transmission system previously defined Solar Power Satellite Systems were investigated. These were the laser power transmission, transportation systems, and an analysis or solid state power transmission. The advantages of each system are presented.

Solid-liquid like phase transition in a confined granular suspension

NASA Astrophysics Data System (ADS)

Sakai, Nariaki; Lechenault, Frederic; Adda Bedia, Mokhtar

We present an experimental study of a liquid-solid like phase transition in a two-dimensional granular media. Particles are placed in a vertical Hele-Show cell filled with a denser solution of cesium-chloride. Thus, when the cell is rotated around its axis, hydrostatic pressure exerts a centripetal force on the particles which confines them towards the center. This force is in competition with gravity, thus by modifying the rotation rate, it is possible to transform continuously and reversibly the sample from a disordered loose state to an ordered packed state. The system presents many similarities with thermal systems at equilibrium like density and interface fluctuations, and the transition between the two phases goes through a coexistence state, where there is nucleation and growth of locally ordered domains which are captured by the correlation function of the hexatic order parameter. We discuss the possibility to extend the grand-canonical formalism to out-of equilibrium systems, in order to uncover a state equation between the density and the pressure in the medium.

SLURM: Simple Linux Utility for Resource Management

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

Jette, M; Dunlap, C; Garlick, J

2002-04-24

Simple Linux Utility for Resource Management (SLURM) is an open source, fault-tolerant, and highly scalable cluster management and job scheduling system for Linux clusters of thousands of nodes. Components include machine status, partition management, job management, and scheduling modules. The design also includes a scalable, general-purpose communication infrastructure. Development will take place in four phases: Phase I results in a solid infrastructure; Phase II produces a functional but limited interactive job initiation capability without use of the interconnect/switch; Phase III provides switch support and documentation; Phase IV provides job status, fault-tolerance, and job queuing and control through Livermore's Distributed Productionmore » Control System (DPCS), a meta-batch and resource management system.« less

Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

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

Hasan, Mohammad Nasim, E-mail: nasim@me.buet.ac.bd.com; Shavik, Sheikh Mohammad, E-mail: shavik@me.buet.ac.bd.com; Rabbi, Kazi Fazle, E-mail: rabbi35.me10@gmail.com

2016-07-12

Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solidmore » platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface. The heat transfer rate is also much higher in case of hydrophilic surface.« less

PSEUDO-BINARY SYSTEMS INVOLVING RARE EARTH LAVES PHASES

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

Wernick, J.H.; Haszko, S.E.; Dorsi, D.

1962-06-01

The phase relations in a number of pseudo-binary systems involving rare earth Laves phases were determined. Complete series of cubic solid-solutions occur in the DyMn/sub 2/HoMn/sub 2/, HoMn/sub 2/-HoFe/sub 2/, DyMn/sub 2/-DyFe/ sub 2/, HoMn/sub 2/-HoAl/ sub 2/, TbMn/sub 2/TbAl/sub 2/, and DyMn/sub 2/-DyAl/ sub 2/ pseudobinary systems. Deviations from linearity in the lattice constants with composition occur in all these systems. Complete series of cubic solidsolutions also exist in the GdAl/sub 2/-ErAl/sub 2/, GdAl/sub 2/-PrAl/sub 2/ , GdAl/sub 2/-NdAl/sub 2/, GdAl/sub 2/-DyAl/sub 2/, TbAl/sub 2/-NdAl/sub 2/, and T bAl/sub 2/-DyAl/sub 2/ systems. For these systems, no deviation from linearitymore » occurs in the lattice constants. For the DyFe/sub 2/-DyAl/sub 2/ and DyCo/sub 2/- DyAl/sub 2/ systems, two new ternary phases, DyFeAl and DyCoAl, form and have the MgZn/sub 2/ structure. Their structures were determined from x-ray powder data only. The electronic state giving rise to the formation of these ternary phases is discussed qualitatively. For the DyMn/sub 2/TmMn/sub 2/ system, the range of composition in which the cubic MgCu/sub 2/ and hexagonal MgZn/sub 2/ structures exist are reported. No complete series of solid solutions or intermediate phases are formed in the DyNi/sub 2/-DyAl/sub 2/ system. (auth)« less

Growth and Interaction of Colloid Nuclei

NASA Astrophysics Data System (ADS)

Lam, Michael-Angelo; Khusid, Boris; Meyer, William; Kondic, Lou

2017-11-01

We study evolution of colloid systems under zero-gravity conditions. In particular, we focus on the regime where there is a coexistence between a liquid and a solid state. Under zero gravity, the dominating process in the bulk of the fluid phase and the solid phase is diffusion. At the moving solid/liquid interface, osmotic pressure is balanced by surface tension, as well as balancing fluxes (conservation of mass) with the kinematics of nuclei growth (Wilson-Frenkel law). Due to the highly nonlinear boundary condition at the moving boundary, care has to be taken when performing numerical simulations. In this work, we present a nonlinear model for colloid nuclei growth. Numerical simulations using a finite volume method are compared with asymptotic analysis of the governing equation and experimental results for nuclei growth. Novel component in our numerical simulations is the inclusion of nonlinear (collective) diffusion terms that depend on the chemical potentials of the colloid in the solid and fluid phase. The results include growth and dissolution of a single colloidal nucleus, as well as evolution of multiple interacting nuclei. Supported by NASA Grant No. NNX16AQ79G.

Powder metallurgy: Solid and liquid phase sintering of copper

NASA Technical Reports Server (NTRS)

Sheldon, Rex; Weiser, Martin W.

1993-01-01

Basic powder metallurgy (P/M) principles and techniques are presented in this laboratory experiment. A copper based system is used since it is relatively easy to work with and is commercially important. In addition to standard solid state sintering, small quantities of low melting metals such as tin, zinc, lead, and aluminum can be added to demonstrate liquid phase sintering and alloy formation. The Taguchi Method of experimental design was used to study the effect of particle size, pressing force, sintering temperature, and sintering time. These parameters can be easily changed to incorporate liquid phase sintering effects and some guidelines for such substitutions are presented. The experiment is typically carried out over a period of three weeks.

Chromatographic Separations Using Solid-Phase Extraction Cartridges: Separation of Wine Phenolics

NASA Astrophysics Data System (ADS)

Brenneman, Charles A.; Ebeler, Susan E.

1999-12-01

We describe a simple laboratory experiment that demonstrates the principles of chromatographic separation using solid-phase extraction columns and red wine. By adjusting pH and mobile phase composition, the wine is separated into three fractions of differing polarity. The content of each fraction can be monitored by UV-vis spectroscopy. When the experiment is combined with experiments involving HPLC or GC separations, students gain a greater appreciation for and understanding of the highly automated instrumental systems currently available. In addition, they learn about the chemistry of polyphenolic compounds, which are present in many foods and beverages and which are receiving much attention for their potentially beneficial health effects.

Space shuttle system program definition. Volume 4: Cost and schedule report

NASA Technical Reports Server (NTRS)

1972-01-01

The supporting cost and schedule data for the second half of the Space Shuttle System Phase B Extension Study is summarized. The major objective for this period was to address the cost/schedule differences affecting final selection of the HO orbiter space shuttle system. The contending options under study included the following booster launch configurations: (1) series burn ballistic recoverable booster (BRB), (2) parallel burn ballistic recoverable booster (BRB), (3) series burn solid rocket motors (SRM's), and (4) parallel burn solid rocket motors (SRM's). The implications of varying payload bay sizes for the orbiter, engine type for the ballistics recoverable booster, and SRM motors for the solid booster were examined.

Environmental solid particle effects on compressor cascade performance

NASA Technical Reports Server (NTRS)

Tabakoff, W.; Balan, C.

1982-01-01

The effect of suspended solid particles on the performance of the compressor cascade was investigated experimentally in a specially built cascade tunnel, using quartz sand particles. The cascades were made of NACA 65(10)10 airfoils. Three cascades were tested, one accelerating cascade and two diffusing cascades. The theoretical analysis assumes inviscid and incompressible two dimensional flow. The momentum exchange between the fluid and the particle is accounted for by the interphase force terms in the fluid momentum equation. The modified fluid phase momentum equations and the continuity equation are reduced to the conventional stream function vorticity formulation. The method treats the fluid phase in the Eulerian system and the particle phase in Lagrangian system. The experimental results indicate a small increase in the blade surface static pressures, while the theoretical results indicate a small decrease. The theoretical analysis, also predicts the loss in total pressure associated with the particulate flow through the cascade.

Solid State Ionic Materials - Proceedings of the 4th Asian Conference on Solid State Ionics

NASA Astrophysics Data System (ADS)

Chowdari, B. V. R.; Yahaya, M.; Talib, I. A.; Salleh, M. M.

1994-07-01

The Table of Contents for the full book PDF is as follows: * Preface * I. INVITED PAPERS * Diffusion of Cations and Anions in Solid Electrolytes * Silver Ion Conductors in the Crystalline State * NMR Studies of Superionic Conductors * Hall Effect and Thermoelectric Power in High Tc Hg-Ba-Ca-Cu-O Ceramics * Solid Electrolyte Materials Prepared by Sol-Gel Chemistry * Preparation of Proton-Conducting Gel Films and their Application to Electrochromic Devices * Thin Film Fuel Cells * Zirconia based Solid Oxide Ion Conductors in Solid Oxide Fuel Cells * The Influence of Anion Substitution on Some Phosphate-based Ion Conducting Glasses * Lithium Intercalation in Carbon Electrodes and its Relevance in Rocking Chair Batteries * Chemical Sensors using Proton Conducting Ceramics * NMR/NQR Studies of Y-Ba-Cu-O Superconductors * Silver Molybdate Glasses and Battery Systems * New Highly Conducting Polymer Ionics and their Application in Electrochemical Devices * Study of Li Electrokinetics on Oligomeric Electrolytes using Microelectrodes * Calculation of Conductivity for Mixed-Phase Electrolytes PEO-MX-Immiscible Additive by Means of Effective Medium Theory * II. CONTRIBUTED PAPERS * Phase Relationship and Electrical Conductivity of Sr-V-O System with Vanadium Suboxide * Amorphous Li+ Ionic Conductors in Li2SO4-Li2O-P2O5 System * Fast Ion Transport in KCl-Al2O3 Composites * The Effect of the Second Phase Precipitation on the Ionic Conductivity of Zr0.85Mg0.15O1.85 * Conductivity Measurements and Phase Relationships in CaCl2-CaHCl Solid Electrolyte * Relationships Between Crystal Structure and Sodium Ion Conductivity in Na7Fe4(AsO4)6 and Na3Al2(AsO4)3 * Electrical Conductivity and Solubility Limit of Ti4+ Ion in Na1+x TiyZr2-ySixP3-xO12 System * Study on Sodium Fast Ion Conductors of Na1+3xAlxTi2-xSi2xP3-2xO12 System * Influences of Zirconia on the Properties of β''-Alumina Ceramics * Decay of Luminescence from Cr3+ Ions in β-Alumina * Lithium Ion Conductivity in the Li4XO4-Li2SO4 (X=Si, Ge, Ti) Systems * A DSC and Conductivity Study of the Influence of Cesium Ion on the Beta-Alpha Transition in Silver Iodide * Phase Diagrams, Stoichiometries and Properties of Bi4V2O11:M2+ Solid Electrolytes * Physical Properties of Electrodeposited Silver Chromotungstate * Pseudopotential Study of Bonding in the Superionic Material AgI: The Effect of Statistical Distribution of Mobile Ions * Cubic Phase Dominant Region in Submicron BaTiO3 Particles * The Crystallization of CoZr Amorphous Alloys via Electrical Resistivity * Cation Ratio Related Properties of Synthetic Mg/Al Layered Double Hydroxide and it's Nanocomposite * DC Conductivity of Nano-Particles of Silver Iodide * Effect of Anomalous Diffusion on Quasielastic Scattering in Superionic Conductors * Computer Simulation Study of Conductivity Enhancement in Superionic-Insulator Composites * Dynamics of Superionic Silver and Copper Iodide Salt Melts * Influence of Dopant Salt AgI, Glass Modifier Ag2O and Glass Formers (SeO3 + MoO3) on Electrical Conductivity in Quaternary Glassy System * Fast Ion Conductivity in the Presence of Competitive Network Formers * Role of Alkali Ions in Borate Glasses * Inelastic Light Scattering in Cadmium Borate Glasses * Investigation on Transport Properties of Mixed Glass System 0.75 [0.75AgI:0.25AgCl]. 0.25[Ag2O:CrO3] * Conduction Mechanism in Lithium Tellurite Glasses * Optimized Silver Tungstoarsenate Glass Electrolyte * Stabilized Superfine Zirconia Powder Prepared by Sol-Gel Process * Study of New PAN-based Electrolytes * Electrical and Thermal Characterization of PVA based Polymer Electrolytes * Conductive Electroactive Polymers: Versatile Solid State Ionic Materials * The Role of Ag2O Addition on the Superconducting Properties of Y-124 Compound * Absorption Spectra Studies of the C60 Films on Transition Metal Film Substrates * Effect of Alumina Dispersal on the Conductivity and Crystallite Size of Polymer Electrolyte * New Mixed Galss-Polymer Solid Electrolytes * The Sputtered La0.5Sr0.5MnO3-Yttria Stabilized Zirconia Composite Electrode in Solid Oxide Fuel Cells * A Solid Electrochemical Ferro Sensor for Molten Matte * SnO2-based Sensor for H2S Monitoring-Electrical Conductivity Measurements and Device Testing * Humidity Sensor using Potassium Tungsten Bronze Synthesized from Peroxo-Polytungstic Acid * Study on Li/LiClO4/V6O13 Test Cells * Fabrication and Characterisation of Some Solid Electrolyte Cells Containing CuI and Silver Oxysalts * Solid State Battery of Proton Conducting Sodium Thiosulphate Pentahydrate * Low Temperature Synthesis of LiMn2O4 for Secondary Lithium Batteries * Effect of Different Cathode Active Materials on Battery Performance with Silver Molybdate Electrolyte Partially Substituted with Zinc Oxide * Fabrication and Characterization of Electrochemical Cells based on Silver Molybdoarsenate and Silver Tungstoarsenate Glass Electrolytes * Lorentz Force Dependence of Dissipation in a Granular Superconductor * Late Entry (Invited paper) * Simultaneous Voltammetry and Spectroscopy of Polyaniline in Propylene Carbonate * Author Index * Tentative List of Participants

Nuclear fuel alloys or mixtures and method of making thereof

DOEpatents

Mariani, Robert Dominick; Porter, Douglas Lloyd

2016-04-05

Nuclear fuel alloys or mixtures and methods of making nuclear fuel mixtures are provided. Pseudo-binary actinide-M fuel mixtures form alloys and exhibit: body-centered cubic solid phases at low temperatures; high solidus temperatures; and/or minimal or no reaction or inter-diffusion with steel and other cladding materials. Methods described herein through metallurgical and thermodynamics advancements guide the selection of amounts of fuel mixture components by use of phase diagrams. Weight percentages for components of a metallic additive to an actinide fuel are selected in a solid phase region of an isothermal phase diagram taken at a temperature below an upper temperature limit for the resulting fuel mixture in reactor use. Fuel mixtures include uranium-molybdenum-tungsten, uranium-molybdenum-tantalum, molybdenum-titanium-zirconium, and uranium-molybdenum-titanium systems.

Solid-Phase and Oscillating Solution Crystallization Behavior of (+)- and (-)-N-Methylephedrine.

PubMed

Tulashie, Samuel Kofi; Polenske, Daniel; Seidel-Morgenstern, Andreas; Lorenz, Heike

2016-11-01

This work involves the study of the solid-phase and solution crystallization behavior of the N-methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed. Copyright © 2016. Published by Elsevier Inc.

A metastable liquid melted from a crystalline solid under decompression

NASA Astrophysics Data System (ADS)

Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kono, Yoshio; Park, Changyong; Kenney-Benson, Curtis; Shen, Guoyin

2017-01-01

A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid-solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. The decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure-temperature region similar to where the supercooled liquid Bi is observed. Akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought.

First-principles thermodynamics study of phase stability in inorganic halide perovskite solid solutions

NASA Astrophysics Data System (ADS)

Bechtel, Jonathon S.; Van der Ven, Anton

2018-04-01

Halide substitution gives rise to a tunable band gap as a function of composition in halide perovskite materials. However, photoinduced phase segregation, observed at room temperature in mixed halide A Pb (IxBr1-x) 3 systems, limits open circuit voltages and decreases photovoltaic device efficiencies. We investigate equilibrium phase stability of orthorhombic P n m a γ -phase CsM (XxY1-x) 3 perovskites where M is Pb or Sn, and X and Y are Br, Cl, or I. Finite-temperature phase diagrams are constructed using a cluster expansion effective Hamiltonian parameterized from first-principles density-functional-theory calculations. Solid solution phases for CsM (IxBr1-x) 3 and CsM (BrxCl1-x) 3 are predicted to be stable well below room temperature while CsM (IxCl1-x) 3 systems have miscibility gaps that extend above 400 K. The height of the miscibility gap correlates with the difference in volume between end members. Also layered ground states are found on the convex hull at x =2 /3 for CsSnBr2Cl ,CsPbI2Br , and CsPbBrCl2. The impact of these ground states on the finite temperature phase diagram is discussed in the context of the experimentally observed photoinduced phase segregation.

Geochemical modeling of reactions and partitioning of trace metals and radionuclides during titration of contaminated acidic sediments.

PubMed

Zhang, Fan; Luo, Wensui; Parker, Jack C; Spalding, Brian P; Brooks, Scott C; Watson, David B; Jardine, Philip M; Gu, Baohua

2008-11-01

Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This studywas undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cation exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/ dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO4(2-) for contaminated sediments indicated close agreement suggesting that the model could potentially be used to predictthe acid-base behavior of the sediment-solution system under variable pH conditions.

From in silica to in silico: retention thermodynamics at solid-liquid interfaces.

PubMed

El Hage, Krystel; Bemish, Raymond J; Meuwly, Markus

2018-06-28

The dynamics of solvated molecules at the solid/liquid interface is essential for a molecular-level understanding for the solution thermodynamics in reversed phase liquid chromatography (RPLC). The heterogeneous nature of the systems and the competing intermolecular interactions makes solute retention in RPLC a surprisingly challenging problem which benefits greatly from modelling at atomistic resolution. However, the quality of the underlying computational model needs to be sufficiently accurate to provide a realistic description of the energetics and dynamics of systems, especially for solution-phase simulations. Here, the retention thermodynamics and the retention mechanism of a range of benzene-derivatives in C18 stationary-phase chains in contact with water/methanol mixtures is studied using point charge (PC) and multipole (MTP) electrostatic models. The results demonstrate that free energy simulations with a faithful MTP representation of the computational model provide quantitative and molecular level insight into the thermodynamics of adsorption/desorption in chromatographic systems while a conventional PC representation fails in doing so. This provides a rational basis to develop more quantitative and validated models for the optimization of separation systems.

Realization of atomistic transitions with colloidal nanoparticles using an ultrafast laser

NASA Astrophysics Data System (ADS)

Akguc, Gursoy; Ilday, Serim; Ilday, Omer; Gulseren, Oguz; Makey, Ghaith; Yavuz, Koray

We report on realization of rapid atomistic transitions with colloidal nanoparticles in a setting that constitutes a dissipative far-from-equilibrium system subject to stochastic forces. Large colloidal crystals (comprising hundreds of particles) can be formed and transitions between solid-liquid-gas phases can be observed effortlessly and within seconds. Furthermore, this system allows us to form and dynamically arrest metastable phases such as glassy structures and to controllably transform a crystal pattern from square to hexagonal lattices and vice versa as well as to observe formation and propagation of crystal defects (i.e. line defects, point defects, planar defects). The mechanism largely relies on an interplay between convective forces induced by femtosecond pulses and strong Brownian motion; the former drags the colloids to form and reinforce the crystal and the latter is analogous to lattice vibrations, which makes it possible to observe phase transitions, defect formation and propagation and lattice transformation. This unique system can help us get insight into the mechanisms underlying various solid state phenomena that were previously studied under slowly evolving (within hours/days), near-equilibrium colloidal systems.

Thermophysical parameters of coconut oil and its potential application as the thermal energy storage system in Indonesia

NASA Astrophysics Data System (ADS)

Putri, Widya A.; Fahmi, Zulfikar; Sutjahja, I. M.; Kurnia, D.; Wonorahardjo, S.

2016-08-01

The high consumption of electric energy for room air conditioning (AC) system in Indonesia has driven the research of potential thermal energy storage system as a passive temperature controller. The application of coconut oil (CO) as the potential candidate for this purpose has been motivated since its working temperature just around the human thermal comfort zone in the tropical area as Indonesia. In this research we report the time-dependent temperature data of CO, which is adopting the T-history method. The analysis of the data revealed a set of thermophysical parameters, consist of the mean specific heats of the solid and liquid, as well as the latent heat of fusion for the phase change transition. The performance of CO to decrease the air temperature was measured in the thermal chamber. From the results it is shown that the latent phase of CO related to the solid-liquid phase transition show the highest capability in heat absorption, directly showing the potential application of CO as thermal energy storage system in Indonesia.

Response of two-phase droplets to intense electromagnetic radiation

NASA Technical Reports Server (NTRS)

Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

1993-01-01

The behavior of two-phase droplets subjected to high intensity radiation pulses is studied. Droplets are highly absorbing solids in weakly absorbing liquid medium. The objective of the study was to define heating thresholds required for causing explosive boiling and secondary atomization of the fuel droplet. The results point to mechanisms for energy storage and transport in two-phase systems.

Thermodynamics of water intrusion in nanoporous hydrophobic solids.

PubMed

Cailliez, Fabien; Trzpit, Mickael; Soulard, Michel; Demachy, Isabelle; Boutin, Anne; Patarin, Joël; Fuchs, Alain H

2008-08-28

We report a joint experimental and molecular simulation study of water intrusion in silicalite-1 and ferrerite zeolites. The main conclusion of this study is that water condensation takes place through a genuine first-order phase transition, provided that the interconnected pores structure is 3-dimensional. In the extreme confinement situation (ferrierite zeolite), condensation takes place through a continuous transition, which is explained by a shift of both the first-order transition line and the critical point with increasing confinement. The present findings are at odds with the common belief that conventional phase transitions cannot take place in microporous solids such as zeolites. The most important features of the intrusion/extrusion process can be understood in terms of equilibrium thermodynamics considerations. We believe that these findings are very general for hydrophobic solids, i.e. for both nonwetting as well as wetting water-solid interface systems.

Drug delivery properties of macroporous polystyrene solid foams.

PubMed

Canal, Cristina; Aparicio, Rosa Maria; Vilchez, Alejandro; Esquena, Jordi; García-Celma, Maria José

2012-01-01

Polymeric porous foams have been evaluated as possible new pharmaceutical dosage forms. These materials were obtained by polymerization in the continuous phase of highly concentrated emulsions prepared by the phase inversion temperature method. Their porosity, specific surface and surface topography were characterized, and the incorporation and release of active principles was studied using ketoprofen as model lipophilic molecule. Solid foams with very high pore volume, mainly inside macropores, were obtained by this method. The pore morphology of the materials was characterized, and very rough topography was observed, which contributed to their nearly superhydrophobic properties. These solid foams could be used as delivery systems for active principles with pharmaceutical interest, and in the present work ketoprofen was used as a model lipophilic molecule. Drug incorporation and release was studied from solid foam disks, using different concentrations of the loading solutions, achieving a delayed release with short lag-time.

Effect of transition dipole phase on high-order-harmonic generation in solid materials

NASA Astrophysics Data System (ADS)

Jiang, Shicheng; Wei, Hui; Chen, Jigen; Yu, Chao; Lu, Ruifeng; Lin, C. D.

2017-11-01

High-order harmonic spectra from solid materials driven by single-color multicycle laser fields sometimes contain even harmonics. In this work we attribute the appearance of even harmonics to the nonzero transition dipole phase (TDP) when the solid system has broken symmetry. By calculating the harmonic efficiency from graphene and gapped graphene by using the semiconductor Bloch equations under the tight-binding approximation, we demonstrate the role of the TDP, which has been ignored for a long time. When the crystal has inversion symmetry, or reflection symmetry with the symmetry plane perpendicular to the laser polarization direction, the TDP can be neglected. Without such symmetry, however, the TDP will lead to the appearance of even harmonics. We further show that the TDP is sensitive to the crystal geometry. To extract the structure information from the harmonic spectra of a solid the TDP cannot be ignored.

Viscoelasticity of nano-alumina dispersions

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

Rand, B.; Fries, R.

1996-06-01

The flow and viscoelastic properties of electrostatically stabilized nano-alumina dispersions have been studied as a function of ionic strength and volume fraction of solids. At low ionic strength the suspensions were deflocculated and showed a transition from viscous to elastic behavior as the solid content increased associated with the onset of double layer interpenetration. The phase transition was progressively shifted to higher solids fractions with increasing ionic strength. At higher ionic strength, above the critical coagulation concentration, the suspensions formed attractive networks characterized by high elasticity. Two independent methods of estimating the effective radius of electrostatically stabilized {open_quotes}soft{close_quotes} particles, a{submore » eff}, are presented based on phase angle data and a modified Dougherty-Krieger equation. The results suggest that a{sub eff} is not constant for a given system but changes with both solids fraction and ionic strength.« less

Radioactivity concentration in liquid and solid phases of scale and sludge generated in the petroleum industry.

PubMed

Paranhos Gazineu, Maria Helena; de Araújo, Andressa Arruda; Brandão, Yana Batista; Hazin, Clovis Abrahão; de O Godoy, José Marcos

2005-01-01

Scales and sludge generated during oil extraction and production can contain uranium, thorium, radium and other natural radionuclides, which can cause exposure of maintenance personnel. This work shows how the oil content can influence the results of measurements of radionuclide concentration in scale and sludge. Samples were taken from a PETROBRAS unit in Northeast Brazil. They were collected directly from the inner surface of water pipes or from barrels stored in the waste storage area of the E&P unit. The oil was separated from the solids with a Soxhlet extractor by using aguarras at 90+/-5 degrees C as solvent. Concentrations of 226Ra and 228Ra in the samples were determined before and after oil extraction by using an HPGe gamma spectrometric system. The results showed an increase in the radionuclide concentration in the solid (dry) phase, indicating that the above radionuclides concentrate mostly in the solid material.

Macrosegregation and nucleation in undercooled Pb-Sn alloys

NASA Technical Reports Server (NTRS)

Degroh, Henry C., III

1989-01-01

A technique resulting in large undercoolings in bulk samples (23g) of lead-tin alloys was developed. Samples of Pb-12.5 wt percent Sn, Pb-61 wt percent Sn, and Pb-77 wt percent Sn were processed with undercoolings ranging from 4 to 34 K and with cooling rates varying between 0.04 and 4 K/sec. The nucleation behavior of the Pb-Sn system was found to be nonreciprocal. The solid Sn phase effectively nucleated the Pb phase of the eutectic; however, large undercoolings developed in Sn-rich eutectic liquid in the presence of the solid Pb phase. This phenomenon is believed to be mainly the result of differences in interfacial energies between solid Sn-eutectic liquid, and solid Pb-eutectic liquid rather than lattice misfit between Pb and Sn. Large amounts of segregation developed in the highly undercooled eutectic ingots. This macrosegregation was found to increase as undercooling increases. Macrosegregation in these undercooled eutectic alloys was found to be primarily due to a sink/float mechanism and the nucleation behavior of the alloy. Lead-rich dendrites are the primary phase in the undercooled eutectic system. These dendrites grow rapidly into the undercooled bath and soon break apart due to recalescence and Sn enrichment of the liquid. These fragmented Pb dendrites are then free to settle to the bottom portion of the ingot causing the macrosegregation observed in this study. A eutectic Pb-Sn alloy undercooled 20 K and cooled at 4 K/sec had a composition of about Pb-72 wt percent Sn at the top and 55 percent Sn at the bottom.

Macrosegregation and nucleation in undercooled Pb-Sn alloys

NASA Technical Reports Server (NTRS)

Degroh, Henry C., III

1989-01-01

A novel technique resulting in large undercoolings in bulk samples (23 g) of lead-tin alloys was developed. Samples of Pb-12.5 wt percent Sn, Pb-61.9 wt.% Sn, and Pb-77 wt.% Sn were processed with undercoolings ranging from 4 to 34 K and with cooling rates varying between 0.04 and 4 K/s. The nucleation behavior of the Pb-Sn system was found to be nonreciprocal. The solid Sn phase effectively nucleated the Pb phase of the eutectic; however, large undercoolings developed in Sn-rich eutectic liquid in the presence of the solid Pb phase. This phenomenon is believed to be mainly the result of differences in interfacial energies between solid Sn-eutectic liquid, and solid Pb-eutectic liquid rather than lattice misfit between Pb and Sn. Large amounts of segregation developed in the highly undercooled eutectic ingots. This macrosegregation was found to increase as undercooling increases. Macrosegregation in these undercooled eutectic alloys was found to be primarily due to a sink/float mechanism and the nucleation behavior of the alloy. Lead-rich dendrites are the primary phase in the undercooled eutectic system. These dendrites grow rapidly into the undercooled bath and soon break apart due to recalescence and Sn enrichment of the liquid. These fragmented Pb dendrites are then free to settle to the bottom portion of the ingot causing the macrosegregation observed in this study. A eutectic Pb-Sn alloy undercooled 20 K and cooled at 4 K/s had a composition of about Pb-72 wt.% Sn at the top and 55% Sn at the bottom.

Fabrication of Heterogeneous-Phase Solid-Solution Promoting Band Structure and Charge Separation for Enhancing Photocatalytic CO2 Reduction: A Case of ZnXCa1-XIn2S4.

PubMed

Zeng, Chao; Huang, Hongwei; Zhang, Tierui; Dong, Fan; Zhang, Yihe; Hu, Yingmo

2017-08-23

Photocatalytic CO 2 reduction into solar fuels illustrates huge charm for simultaneously settling energy and environmental issues. The photoreduction ability of a semiconductor is closely correlated to its conduction band (CB) position. A homogeneous-phase solid-solution with the same crystal system always has a monotonously changed CB position, and the high CB level has to be sacrificed to achieve a benign photoabsorption. Herein, we report the fabrication of heterogeneous-phase solid-solution Zn X Ca 1-X In 2 S 4 between trigonal ZnIn 2 S 4 and cubic CaIn 2 S 4 . The Zn X Ca 1-X In 2 S 4 solid solutions with orderly tuned photoresponsive range from 540 to 640 nm present a more negative CB level and highly enhanced charge-separation efficiency. Profiting from these merits, all of these Zn X Ca 1-X In 2 S 4 solid solutions exhibit remarkably strengthened photocatalytic CO 2 reduction performance under visible light (λ > 420 nm) irradiation. Zn 0.4 Ca 0.6 In 2 S 4 , bearing the most negative CB position and highest charge-separation efficiency, casts the optimal photocatalytic CH 4 and CO evolution rates, which reach 16.7 and 6.8 times higher than that of ZnIn 2 S 4 and 7.2 and 3.9 times higher than that of CaIn 2 S 4 , respectively. To verify the crucial role of the heterogeneous-phase solid solution in promoting the band structure and photocatalytic performance, another heterogeneous-phase solid-solution Zn X Cd 1-X In 2 S 4 has been synthesized. It also displays an upshifted CB level and promoted charge separation. This work may provide a new perspective into the development of an efficient visible-light driven photocatalyst for CO 2 reduction and other photoreduction reactions.

Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation

DOE PAGES

Nicholas, Sarah L.; Erickson, Melinda L.; Woodruff, Laurel G.; ...

2017-05-19

Arsenic (As) is a geogenic contaminant affecting groundwater in geologically diverse systems globally. Arsenic release from aquifer sediments to groundwater is favored when biogeochemical conditions, especially oxidation-reduction (redox) potential, in aquifers fluctuate. The specific objective of this research is to identify the solid-phase sources and geochemical mechanisms of release of As in aquifers of the Des Moines Lobe glacial advance. The overarching concept is that conditions present at the aquifer-aquitard interfaces promote a suite of geochemical reactions leading to mineral alteration and release of As to groundwater. A microprobe X-ray absorption spectroscopy (μXAS) approach is developed and applied to rotosonicmore » drill core samples to identify the solid-phase speciation of As in aquifer, aquitard, and aquifer-aquitard interface sediments. This approach addresses the low solid-phase As concentrations, as well as the fine-scale physical and chemical heterogeneity of the sediments. The spectroscopy data are analyzed using novel cosine-distance and correlation-distance hierarchical clustering for Fe 1s and As 1s μXAS datasets. The solid-phase Fe and As speciation is then interpreted using sediment and well-water chemical data to propose solid-phase As reservoirs and release mechanisms. The results confirm that in two of the three locations studied, the glacial sediment forming the aquitard is the source of As to the aquifer sediments. The results are consistent with three different As release mechanisms: (1) desorption from Fe (oxyhydr)oxides, (2) reductive dissolution of Fe (oxyhydr)oxides, and (3) oxidative dissolution of Fe sulfides. The findings confirm that glacial sediments at the interface between aquifer and aquitard are geochemically active zones for As. The diversity of As release mechanisms is consistent with the geographic heterogeneity seen in the distribution of elevated-As wells.« less

Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation

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

Nicholas, Sarah L.; Erickson, Melinda L.; Woodruff, Laurel G.

Arsenic (As) is a geogenic contaminant affecting groundwater in geologically diverse systems globally. Arsenic release from aquifer sediments to groundwater is favored when biogeochemical conditions, especially oxidation-reduction (redox) potential, in aquifers fluctuate. The specific objective of this research is to identify the solid-phase sources and geochemical mechanisms of release of As in aquifers of the Des Moines Lobe glacial advance. The overarching concept is that conditions present at the aquifer-aquitard interfaces promote a suite of geochemical reactions leading to mineral alteration and release of As to groundwater. A microprobe X-ray absorption spectroscopy (μXAS) approach is developed and applied to rotosonicmore » drill core samples to identify the solid-phase speciation of As in aquifer, aquitard, and aquifer-aquitard interface sediments. This approach addresses the low solid-phase As concentrations, as well as the fine-scale physical and chemical heterogeneity of the sediments. The spectroscopy data are analyzed using novel cosine-distance and correlation-distance hierarchical clustering for Fe 1s and As 1s μXAS datasets. The solid-phase Fe and As speciation is then interpreted using sediment and well-water chemical data to propose solid-phase As reservoirs and release mechanisms. The results confirm that in two of the three locations studied, the glacial sediment forming the aquitard is the source of As to the aquifer sediments. The results are consistent with three different As release mechanisms: (1) desorption from Fe (oxyhydr)oxides, (2) reductive dissolution of Fe (oxyhydr)oxides, and (3) oxidative dissolution of Fe sulfides. The findings confirm that glacial sediments at the interface between aquifer and aquitard are geochemically active zones for As. The diversity of As release mechanisms is consistent with the geographic heterogeneity seen in the distribution of elevated-As wells.« less

Benzocaine polymorphism: pressure-temperature phase diagram involving forms II and III.

PubMed

Gana, Inès; Barrio, Maria; Do, Bernard; Tamarit, Josep-Lluís; Céolin, René; Rietveld, Ivo B

2013-11-18

Understanding the phase behavior of an active pharmaceutical ingredient in a drug formulation is required to avoid the occurrence of sudden phase changes resulting in decrease of bioavailability in a marketed product. Benzocaine is known to possess three crystalline polymorphs, but their stability hierarchy has so far not been determined. A topological method and direct calorimetric measurements under pressure have been used to construct the topological pressure-temperature diagram of the phase relationships between the solid phases II and III, the liquid, and the vapor phase. In the process, the transition temperature between solid phases III and II and its enthalpy change have been determined. Solid phase II, which has the highest melting point, is the more stable phase under ambient conditions in this phase diagram. Surprisingly, solid phase I has not been observed during the study, even though the scarce literature data on its thermal behavior appear to indicate that it might be the most stable one of the three solid phases. Copyright © 2013 Elsevier B.V. All rights reserved.

The global phase diagram of the Gay-Berne model

NASA Astrophysics Data System (ADS)

de Miguel, Enrique; Vega, Carlos

2002-10-01

The phase diagram of the Gay-Berne model with anisotropy parameters κ=3, κ'=5 has been evaluated by means of computer simulations. For a number of temperatures, NPT simulations were performed for the solid phase leading to the determination of the free energy of the solid at a reference density. Using the equation of state and free energies of the isotropic and nematic phases available in the existing literature the fluid-solid equilibrium was calculated for the temperatures selected. Taking these fluid-solid equilibrium results as the starting points, the fluid-solid equilibrium curve was determined for a wide range of temperatures using Gibbs-Duhem integration. At high temperatures the sequence of phases encountered on compression is isotropic to nematic, and then nematic to solid. For reduced temperatures below T=0.85 the sequence is from the isotropic phase directly to the solid state. In view of this we locate the isotropic-nematic-solid triple point at TINS=0.85. The present results suggest that the high-density phase designated smectic B in previous simulations of the model is in fact a molecular solid and not a smectic liquid crystal. It seems that no thermodynamically stable smectic phase appears for the Gay-Berne model with the choice of parameters used in this work. We locate the vapor-isotropic liquid-solid triple point at a temperature TVIS=0.445. Considering that the critical temperatures is Tc=0.473, the Gay-Berne model used in this work presents vapor-liquid separation over a rather narrow range of temperatures. It is suggested that the strong lateral attractive interactions present in the Gay-Berne model stabilizes the layers found in the solid phase. The large stability of the solid phase, particularly at low temperatures, would explain the unexpectedly small liquid range observed in the vapor-liquid region.

Phase transformations in the reaction cell of TiNi-based sintered systems

NASA Astrophysics Data System (ADS)

Artyukhova, Nadezhda; Anikeev, Sergey; Yasenchuk, Yuriy; Chekalkin, Timofey; Gunther, Victor; Kaftaranova, Maria; Kang, Ji-Hoon; Kim, Ji-Soon

2018-05-01

The present work addresses the structural-phase state changes of porous TiNi-based compounds fabricated by reaction sintering (RS) of Ti and Ni powders with Co, Mo, and no additives introduced. The study also emphasizes the features of a reaction cell (RC) during the transition from the solid- to liquid-phase sintering. Mechanisms of phase transformations occurring in the solid phase, involving the low-melting Ti2Ni phase within the RC, have been highlighted. Also, the intermediate Ti2Ni phase had a crucial role to provide both the required RS behavior and modified phase composition of RS samples, and besides, it is found to be responsible for the near-equiatomic TiNi saturation of the melt. Both cobalt and molybdenum additives are shown to cause additional structuring of the transition zone (TZ) at the Ti2Ni‑TiNi interface and broadening of this zone. The impact of Co and Mo on the Ti2Ni phase is evident through fissuring of this phase layer, which is referred to solidified stresses increased in the layer due to post-alloying defects in the structure.

Theoretical calculation of the melting curve of Cu-Zr binary alloys

DOE PAGES

Gunawardana, K. G.S.H.; Wilson, S. R.; Mendelev, M. I.; ...

2014-11-14

Helmholtz free energies of the dominant binary crystalline solids found in the Cu-Zr system at high temperatures close to the melting curve are calculated. This theoretical approach combines fundamental measure density functional theory (applied to the hard-sphere reference system) and a perturbative approach to include the attractive interactions. The studied crystalline solids are Cu(fcc), Cu 51Zr 14(β), CuZr(B 2), CuZr 2(C11b), Zr(hcp), and Zr(bcc). The calculated Helmholtz free energies of crystalline solids are in good agreement with results from molecular-dynamics (MD) simulations. Using the same perturbation approach, the liquid phase free energies are calculated as a function of composition andmore » temperature, from which the melting curve of the entire composition range of this system can be obtained. Phase diagrams are determined in this way for two leading embedded atom method potentials, and the results are compared with experimental data. Furthermore, theoretical melting temperatures are compared both with experimental values and with values obtained directly from MD simulations at several compositions.« less

Perspective: THz-driven nuclear dynamics from solids to molecules

PubMed Central

Hamm, Peter; Meuwly, Markus; Johnson, Steve L.; Beaud, Paul; Staub, Urs

2017-01-01

Recent years have seen dramatic developments in the technology of intense pulsed light sources in the THz frequency range. Since many dipole-active excitations in solids and molecules also lie in this range, there is now a tremendous potential to use these light sources to study linear and nonlinear dynamics in such systems. While several experimental investigations of THz-driven dynamics in solid-state systems have demonstrated a variety of interesting linear and nonlinear phenomena, comparatively few efforts have been made to drive analogous dynamics in molecular systems. In the present Perspective article, we discuss the similarities and differences between THz-driven dynamics in solid-state and molecular systems on both conceptual and practical levels. We also discuss the experimental parameters needed for these types of experiments and thereby provide design criteria for a further development of this new research branch. Finally, we present a few recent examples to illustrate the rich physics that may be learned from nonlinear THz excitations of phonons in solids as well as inter-molecular vibrations in liquid and gas-phase systems. PMID:29308420

Perspective: THz-driven nuclear dynamics from solids to molecules.

PubMed

Hamm, Peter; Meuwly, Markus; Johnson, Steve L; Beaud, Paul; Staub, Urs

2017-11-01

Recent years have seen dramatic developments in the technology of intense pulsed light sources in the THz frequency range. Since many dipole-active excitations in solids and molecules also lie in this range, there is now a tremendous potential to use these light sources to study linear and nonlinear dynamics in such systems. While several experimental investigations of THz-driven dynamics in solid-state systems have demonstrated a variety of interesting linear and nonlinear phenomena, comparatively few efforts have been made to drive analogous dynamics in molecular systems. In the present Perspective article, we discuss the similarities and differences between THz-driven dynamics in solid-state and molecular systems on both conceptual and practical levels. We also discuss the experimental parameters needed for these types of experiments and thereby provide design criteria for a further development of this new research branch. Finally, we present a few recent examples to illustrate the rich physics that may be learned from nonlinear THz excitations of phonons in solids as well as inter-molecular vibrations in liquid and gas-phase systems.

Ultrasensitive microfluidic solid-phase ELISA using an actuatable microwell-patterned PDMS chip.

PubMed

Wang, Tanyu; Zhang, Mohan; Dreher, Dakota D; Zeng, Yong

2013-11-07

Quantitative detection of low abundance proteins is of significant interest for biological and clinical applications. Here we report an integrated microfluidic solid-phase ELISA platform for rapid and ultrasensitive detection of proteins with a wide dynamic range. Compared to the existing microfluidic devices that perform affinity capture and enzyme-based optical detection in a constant channel volume, the key novelty of our design is two-fold. First, our system integrates a microwell-patterned assay chamber that can be pneumatically actuated to significantly reduce the volume of chemifluorescent reaction, markedly improving the sensitivity and speed of ELISA. Second, monolithic integration of on-chip pumps and the actuatable assay chamber allow programmable fluid delivery and effective mixing for rapid and sensitive immunoassays. Ultrasensitive microfluidic ELISA was demonstrated for insulin-like growth factor 1 receptor (IGF-1R) across at least five orders of magnitude with an extremely low detection limit of 21.8 aM. The microwell-based solid-phase ELISA strategy provides an expandable platform for developing the next-generation microfluidic immunoassay systems that integrate and automate digital and analog measurements to further improve the sensitivity, dynamic ranges, and reproducibility of proteomic analysis.

Mineral phases and metals in baghouse dust from secondary aluminum production

EPA Science Inventory

Baghouse dust (BHD) is a solid waste generated by air pollution control systems during secondary aluminum processing (SAP). Management and disposal of BHD can be challenging in the U.S. and elsewhere. In this study, the mineral phases, metal content and metal leachability of 78...

Determination of haloacetic acids in water using layered double hydroxides as a sorbent in dispersive solid-phase extraction followed by liquid chromatography with tandem mass spectrometry.

PubMed

Alsharaa, Abdulnaser; Sajid, Muhammad; Basheer, Chanbasha; Alhooshani, Khalid; Lee, Hian Kee

2016-09-01

In the present study, highly efficient and simple dispersive solid-phase extraction procedure for the determination of haloacetic acids in water samples has been established. Three different types of layered double hydroxides were synthesized and used as a sorbent in dispersive solid-phase extraction. Due to the interesting behavior of layered double hydroxides in an acidic medium (pH˂4), the analyte elution step was not needed; the layered double hydroxides are simply dissolved in acid immediately after extraction to release the analytes which are then directly introduced into a liquid chromatography with tandem mass spectrometry system for analysis. Several dispersive solid-phase extraction parameters were optimized to increase the extraction efficiency of haloacetic acids such as temperature, extraction time and pH. Under optimum conditions, good linearity was achieved over the concentration range of 0.05-100 μg/L with detection limits in the range of 0.006-0.05 μg/L. The relative standard deviations were 0.33-3.64% (n = 6). The proposed method was applied to different water samples collected from a drinking water plant to determine the concentrations of haloacetic acids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of a molecularly imprinted polymer for determination of steroids in goat milk by matrix solid phase dispersion.

PubMed

Gañán, Judith; Morante-Zarcero, Sonia; Gallego-Picó, Alejandrina; Garcinuño, Rosa María; Fernández-Hernando, Pilar; Sierra, Isabel

2014-08-01

A molecularly imprinted polymer-matrix solid-phase dispersion methodology for simultaneous determination of five steroids in goat milk samples was proposed. Factors affecting the extraction recovery such as sample/dispersant ratio and washing and elution solvents were investigated. The molecularly imprinted polymer used as dispersant in the matrix solid-phase dispersion procedure showed high affinity to steroids, and the obtained extracts were sufficiently cleaned to be directly analyzed. Analytical separation was performed by micellar electrokinetic chromatography using a capillary electrophoresis system equipped with a diode array detector. A background electrolyte composed of borate buffer (25mM, pH 9.3), sodium dodecyl sulfate (10mM) and acetonitrile (20%) was used. The developed MIP-MSPD methodology was applied for direct determination of testosterone (T), estrone (E1), 17β-estradiol (17β-E2), 17α-ethinylestradiol (EE2) and progesterone (P) in different goat milk samples. Mean recoveries obtained ranged from 81% to 110%, with relative standard deviations (RSD)≤12%. The molecularly imprinted polymer-matrix solid-phase dispersion method is fast, selective, cost-effective and environment-friendly compared with other pretreatment methods used for extraction of steroids in milk. Copyright © 2014 Elsevier B.V. All rights reserved.

Drowning-out crystallisation of sodium sulphate using aqueous two-phase systems.

PubMed

Taboada, M E; Graber, T A; Asenjo, J A; Andrews, B A

2000-06-23

A novel method to obtain crystals of pure, anhydrous salt, using aqueous two-phase systems was studied. A concentrated salt solution is mixed with polyethylene glycol (PEG), upon which three phases are formed: salt crystals, a PEG-rich liquid and a salt-rich liquid. After removal of the solid salt, a two-phase system is obtained. Both liquid phases are recycled, allowing the design of a continuous process, which could be exploited industrially. The phase diagram of the system water-Na2SO4-PEG 3350 at 28 degrees C was used. Several process alternatives are proposed and their economic potential is discussed. The process steps needed to produce sodium sulphate crystals include mixing, crystallisation, settling and, optionally, evaporation of water. The yield of sodium sulphate increases dramatically if an evaporation step is used.

Metaproteomics reveals major microbial players and their biodegradation functions in a large-scale aerobic composting plant

PubMed Central

Liu, Dongming; Li, Mingxiao; Xi, Beidou; Zhao, Yue; Wei, Zimin; Song, Caihong; Zhu, Chaowei

2015-01-01

Composting is an appropriate management alternative for municipal solid waste; however, our knowledge about the microbial regulation of this process is still scare. We employed metaproteomics to elucidate the main biodegradation pathways in municipal solid waste composting system across the main phases in a large-scale composting plant. The investigation of microbial succession revealed that Bacillales, Actinobacteria and Saccharomyces increased significantly with respect to abundance in composting process. The key microbiologic population for cellulose degradation in different composting stages was different. Fungi were found to be the main producers of cellulase in earlier phase. However, the cellulolytic fungal communities were gradually replaced by a purely bacterial one in active phase, which did not support the concept that the thermophilic fungi are active through the thermophilic phase. The effective decomposition of cellulose required the synergy between bacteria and fungi in the curing phase. PMID:25989417

Linkage of microbial kinetics and bacterial community structure of MBR and hybrid MBBR-MBR systems to treat salinity-amended urban wastewater.

PubMed

Rodriguez-Sanchez, Alejandro; Leyva-Diaz, Juan Carlos; Gonzalez-Martinez, Alejandro; Poyatos, Jose Manuel

2017-11-01

Three pilot-scale bioreactors were started up and operated under salinity-amended urban wastewater feeding. The bioreactors were configured as membrane bioreactor and two different hybrid, moving bed biofilm reactor-membrane bioreactor and operated with a hydraulic retention time of 9.5 h, a solid residence time of 11.75 days and a total solids concentration of 2500 mg L -1 . The three systems showed excellent performance in suspended solids, BOD 5 , and COD removal (values of 96-100%, 97-99%, and 88-90%, respectively), but poor nitrogen removal (values of 20-30%). The bacterial community structure during the start-up phase and the stabilization phase were different, as showed by β-diversity analyses. The differences between aerobic and anoxic biomass-and between suspended and attached biomass-were higher at the start-up phase than at the stabilization phase. The start-up phase showed high abundances of Chiayiivirga (mean values around 3-12% relative abundance) and Luteimonas (5-8%), but in the stabilization phase, the domination belonged to Thermomonas (3-14%), Nitrobacter (3-7%), Ottowia (3-11.5%), and Comamonas (2-6%), among others. Multivariate redundancy analyses showed that Thermomonas and Nitrosomonas were positively correlated with fast autotrophic kinetics, while Caulobacter and Ottowia were positively correlated with fast heterotrophic kinetics. Nitrobacter, Rhodanobacter, and Comamonas were positively correlated with fast autotrophic and heterotrophic kinetics. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1483-1495, 2017. © 2017 American Institute of Chemical Engineers.

Dehydrogenation of n-Alkanes by Solid-Phase Molecular Pincer-Iridium Catalysts. High Yields of α-Olefin Product.

PubMed

Kumar, Akshai; Zhou, Tian; Emge, Thomas J; Mironov, Oleg; Saxton, Robert J; Krogh-Jespersen, Karsten; Goldman, Alan S

2015-08-12

We report the transfer-dehydrogenation of gas-phase alkanes catalyzed by solid-phase, molecular, pincer-ligated iridium catalysts, using ethylene or propene as hydrogen acceptor. Iridium complexes of sterically unhindered pincer ligands such as (iPr4)PCP, in the solid phase, are found to give extremely high rates and turnover numbers for n-alkane dehydrogenation, and yields of terminal dehydrogenation product (α-olefin) that are much higher than those previously reported for solution-phase experiments. These results are explained by mechanistic studies and DFT calculations which jointly lead to the conclusion that olefin isomerization, which limits yields of α-olefin from pincer-Ir catalyzed alkane dehydrogenation, proceeds via two mechanistically distinct pathways in the case of ((iPr4)PCP)Ir. The more conventional pathway involves 2,1-insertion of the α-olefin into an Ir-H bond of ((iPr4)PCP)IrH2, followed by 3,2-β-H elimination. The use of ethylene as hydrogen acceptor, or high pressures of propene, precludes this pathway by rapid hydrogenation of these small olefins by the dihydride. The second isomerization pathway proceeds via α-olefin C-H addition to (pincer)Ir to give an allyl intermediate as was previously reported for ((tBu4)PCP)Ir. The improved understanding of the factors controlling rates and selectivity has led to solution-phase systems that afford improved yields of α-olefin, and provides a framework required for the future development of more active and selective catalytic systems.

High-density near-field optical disc recording using phase change media and polycarbonate substrate

NASA Astrophysics Data System (ADS)

Shinoda, Masataka; Saito, Kimihiro; Ishimoto, Tsutomu; Kondo, Takao; Nakaoki, Ariyoshi; Furuki, Motohiro; Takeda, Minoru; Akiyama, Yuji; Shimouma, Takashi; Yamamoto, Masanobu

2004-09-01

We developed a high density near field optical recording disc system with a solid immersion lens and two laser sources. In order to realize the near field optical recording, we used a phase change recording media and a molded polycarbonate substrate. The near field optical pick-up consists of a solid immersion lens with numerical aperture of 1.84. The clear eye pattern of 90.2 GB capacity (160nm track pitch and 62 nm per bit) was observed. The jitter using a limit equalizer was 10.0 % without cross-talk. The bit error rate using an adaptive PRML with 8 taps was 3.7e-6 without cross-talk. We confirmed that the near field optical disc system is a promising technology for a next generation high density optical disc system.

Demonstration-scale evaluation of a novel high-solids anaerobic digestion process for converting organic wastes to fuel gas and compost.

PubMed

Rivard, C J; Duff, B W; Dickow, J H; Wiles, C C; Nagle, N J; Gaddy, J L; Clausen, E C

1998-01-01

Early evaluations of the bioconversion potential for combined wastes such as tuna sludge and sorted municipal solid waste (MSW) were conducted at laboratory scale and compared conventional low-solids, stirred-tank anaerobic systems with the novel, high-solids anaerobic digester (HSAD) design. Enhanced feedstock conversion rates and yields were determined for the HSAD system. In addition, the HSAD system demonstrated superior resiliency to process failure. Utilizing relatively dry feedstocks, the HSAD system is approximately one-tenth the size of conventional low-solids systems. In addition, the HSAD system is capable of organic loading rates (OLRs) on the order of 20-25 g volatile solids per liter digester volume per d (gVS/L/d), roughly 4-5 times those of conventional systems. Current efforts involve developing a demonstration-scale (pilot-scale) HSAD system. A two-ton/d plant has been constructed in Stanton, CA and is currently in the commissioning/startup phase. The purposes of the project are to verify laboratory- and intermediate-scale process performance; test the performance of large-scale prototype mechanical systems; demonstrate the long-term reliability of the process; and generate the process and economic data required for the design, financing, and construction of full-scale commercial systems. This study presents conformational fermentation data obtained at intermediate-scale and a snapshot of the pilot-scale project.

Thermodynamic approach to the paradox of diamond formation with simultaneous graphite etching in the low pressure synthesis of diamond

NASA Astrophysics Data System (ADS)

Hwang, Nong M.; Yoon, Duk Y.

1996-03-01

In spite of the critical handicap from the thermodynamic point of view, the atomic hydrogen hypothesis is strongly supported by experimental observations of diamond deposition with simultaneous graphite etching. Thermodynamic analysis of the CH system showed that at ˜ 1500 K, carbon solubility in the gas phase is minimal and thus, the equilibrium fraction of solid carbon is maximal. Depending on whether gas phase nucleation takes place or not, the driving force is for deposition or for etching of solid carbon below ˜ 1500 K for the input gas of the typical mixture of 1% CH 499% H 2. The previous observation of etching of the graphite substrate is not expected unless solid carbon precipitated in the gas phase. By rigorous thermodynamic analysis of the previous experimental observations of diamond deposition with simultaneous graphite etching, we suggested that the previous implicit assumption that diamond deposits by an atomic unit should be the weakest point leading to the thermodynamic paradox. The experimental observations could be successfully explained without violating thermodynamics by assuming that the diamond phase had nucleated in the gas phase as fine clusters.

Effect of the fcc-hcp martensitic transition on the equation of state of solid krypton up to 140 GPa

NASA Astrophysics Data System (ADS)

Rosa, A. D.; Garbarino, G.; Briggs, R.; Svitlyk, V.; Morard, G.; Bouhifd, M. A.; Jacobs, J.; Irifune, T.; Mathon, O.; Pascarelli, S.

2018-03-01

Solid krypton (Kr) undergoes a pressure-induced martensitic phase transition from a face-centered cubic (fcc) to a hexagonal close-packed (hcp) structure. These two phases coexist in a very wide pressure domain inducing important modifications of the bulk properties of the resulting mixed phase system. Here, we report a detailed in situ x-ray diffraction and absorption study of the influence of the fcc-hcp phase transition on the compression behavior of solid krypton in an extended pressure domain up to 140 GPa. The onset of the hcp-fcc transformation was observed in this study at around 2.7 GPa and the coexistence of these two phases up to 140 GPa, the maximum investigated pressure. The appearance of the hcp phase is also evidenced by the pressure-induced broadening and splitting of the first peak in the XANES spectra. We demonstrate that the transition is driven by a continuous nucleation and intergrowth of nanometric hcp stacking faults that evolve in the fcc phase. These hcp stacking faults are unaffected by high-temperature annealing, suggesting that plastic deformation is not at their origin. The apparent small Gibbs free-energy differences between the two structures that decrease upon compression may explain the nucleation of hcp stacking faults and the large coexistence domain of fcc and hcp krypton. We observe a clear anomaly in the equation of state of the fcc solid at ˜20 GPa when the proportion of the hcp form reaches ˜20 % . We demonstrate that this anomaly is related to the difference in stiffness between the fcc and hcp phases and propose two distinct equation of states for the low and high-pressure regimes.

Shuttle: forever young?

PubMed

Sietzen, Frank

2002-01-01

NASA has started a 4-phase program of upgrades designed to increase safety and extend use of the space shuttles through the year 2020. Phase I is aimed at improving vehicle safety and supporting the space station. Phase II is aimed at combating obsolescence and includes a checkout launch and control system and protection from micrometeoroids and orbital debris. Phase III is designed to expand or enhance the capabilities of the shuttle and includes development of an auxiliary power unit, avionics, a channel-wall nozzle, extended nose landing gear, long-life fuel cells, a nontoxic orbital maneuvering system/reaction control system, and a water membrane evaporator. Phase IV is aimed at design of system changes that would alter the shuttle mold line and configuration; projects include a five-segment solid rocket booster, liquid flyback boosters, and a crew escape module.

Disorder trapping by rapidly moving phase interface in an undercooled liquid

NASA Astrophysics Data System (ADS)

Galenko, Peter; Danilov, Denis; Nizovtseva, Irina; Reuther, Klemens; Rettenmayr, Markus

2017-08-01

Non-equilibrium phenomena such as the disappearance of solute drag, the origin of solute trapping and evolution of disorder trapping occur during fast transformations with originating metastable phases [D.M. Herlach, P.K. Galenko, D. Holland-Moritz, Metastable solids from undrercooled melts (Elsevier, Amsterdam, 2007)]. In the present work, a theoretical investigation of disorder trapping by a rapidly moving phase interface is presented. Using a model of fast phase transformations, a system of governing equations for the diffusion of atoms, and the evolution of both long-range order parameter and phase field variable is formulated. First numerical solutions are carried out for a congruently melting binary alloy system.

Liquid crystalline phase behavior in systems of hard-sphere chains

NASA Astrophysics Data System (ADS)

Williamson, Dave C.; Jackson, George

1998-06-01

A study of the liquid crystalline phase transitions in a system of hard-sphere chains is presented. The chains comprise m=7 tangentially bonded hard-sphere segments in a linear conformation (LHSC). The isothermal-isobaric Monte Carlo simulation technique is used to obtain the equation of state of the system both by compressing the isotropic (I) liquid and by expanding the solid (K). As well as the usual isotropic and solid phases, nematic and smectic-A liquid crystalline states are seen. A large degree of hysteresis is found in the neighborhood of the I-N transition. The results for the rigid LHSC system were compared with existing data for the corresponding semiflexible hard-sphere chains (FHSC): the flexibility has a large destabilizing effect on the nematic phase and consequently it postpones the I-N transition. The results of the simulations are also compared with rescaled Onsager theories for the I-N transition. It is rather surprising to find that the Parsons approach, which has been so successful for other hard-core models such as spherocylinders and ellipsoids, gives very poor results. The related approach of Vega and Lago gives a good description of the I-N phase transition. The procedure of Vega and Lago, as with all two-body resummations of the Onsager theory, only gives a qualitative description of the nematic order.

Critical Issues for Producing UHTC-Brazed Joints: Wetting and Reactivity

NASA Astrophysics Data System (ADS)

Passerone, A.; Muolo, M. L.; Valenza, F.

2016-08-01

A brief survey is presented of the most important interaction phenomena occurring at the solid-liquid interfaces in metal-ceramic systems at high temperatures, with special attention to the most recent developments concerning wetting and joining transition metals diborides. These phenomena are described and discussed from both the experimental and theoretical points of view in relation to joining ceramic and metal-ceramic systems by means of processes in the presence of a liquid phase (brazing, TLPB etc.). It is shown that wetting and the formation of interfacial dissolution regions are the results of the competition between different phenomena: dissolution of the ceramic in the liquid phase, reaction and formation of new phases at the solid-liquid interface, and drop spreading along the substrate surface. We emphasize the role of phase diagrams to support both the design of the experiments and the choice of active alloying elements, and to interpret the evolution of the system in relation to temperature and composition. In this respect, the sessile-drop technique has been shown to be helpful in assessing critical points of newly calculated phase diagrams. These studies are essential for the design of joining processes, for the creation of composite materials, and are of a particular relevance when applied to UHTC materials.

Application of binomial-edited CPMG to shale characterization

USGS Publications Warehouse

Washburn, Kathryn E.; Birdwell, Justin E.

2014-01-01

Unconventional shale resources may contain a significant amount of hydrogen in organic solids such as kerogen, but it is not possible to directly detect these solids with many NMR systems. Binomial-edited pulse sequences capitalize on magnetization transfer between solids, semi-solids, and liquids to provide an indirect method of detecting solid organic materials in shales. When the organic solids can be directly measured, binomial-editing helps distinguish between different phases. We applied a binomial-edited CPMG pulse sequence to a range of natural and experimentally-altered shale samples. The most substantial signal loss is seen in shales rich in organic solids while fluids associated with inorganic pores seem essentially unaffected. This suggests that binomial-editing is a potential method for determining fluid locations, solid organic content, and kerogen–bitumen discrimination.

The ATS-F interferometer - A precision wide field-of-view attitude sensor. [solid state system design

NASA Technical Reports Server (NTRS)

Teichman, M. A.; Marek, F. L.; Browning, J. J.; Parr, A. K.

1974-01-01

An RF phase interferometer has been integrated into the ATS-F spacecraft attitude control system. Laboratory measurements indicate that the interferometer is capable of determining spacecraft attitude in pitch and roll to an accuracy of 0.18 deg over a field-of-view of plus or minus 12.5 deg about the spacecraft normal axis with an angular resolution of 0.004 deg. The system is completely solid state, weighs 17 pounds, and consumes 12.5 W of DC power.

Fiber-optic projected-fringe digital interferometry

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.; Beheim, Glenn

1990-01-01

A phase-stepped projected-fringe interferometer was developed which uses a closed-loop fiber-optic phase-control system to make very accurate surface profile measurements. The closed-loop phase-control system greatly reduces phase-stepping error, which is frequently the dominant source of error in digital interferometers. Two beams emitted from a fiber-optic coupler are combined to form an interference fringe pattern on a diffusely reflecting object. Reflections off of the fibers' output faces are used to create a phase-indicating signal for the closed-loop optical phase controller. The controller steps the phase difference between the two beams by pi/2 radians in order to determine the object's surface profile using a solid-state camera and a computer. The system combines the ease of alignment and automated data reduction of phase-stepping projected-fringe interferometry with the greatly improved phase-stepping accuracy of our closed-loop phase-controller. The system is demonstrated by measuring the profile of a plate containing several convex surfaces whose heights range from 15 to 25 micron high.

Experimental study of the Ca-Mg-Zn system using diffusion couples and key alloys

NASA Astrophysics Data System (ADS)

Zhang, Yi-Nan; Kevorkov, Dmytro; Bridier, Florent; Medraj, Mamoun

2011-03-01

Nine diffusion couples and 32 key samples were prepared to map the phase diagram of the Ca-Mg-Zn system. Phase relations and solubility limits were determined for binary and ternary compounds using scanning electron microscopy, electron probe microanalysis and x-ray diffraction (XRD). The crystal structure of the ternary compounds was studied by XRD and electron backscatter diffraction. Four ternary intermetallic (IM) compounds were identified in this system: Ca3MgxZn15-x (4.6<=x<=12 at 335 °C, IM1), Ca14.5Mg15.8Zn69.7 (IM2), Ca2Mg5Zn13 (IM3) and Ca1.5Mg55.3Zn43.2 (IM4). Three binary compounds were found to have extended solid solubility into ternary systems: CaZn11, CaZn13 and Mg2Ca form substitutional solid solutions where Mg substitutes for Zn atoms in the first two compounds, and Zn substitutes for both Ca and Mg atoms in Mg2Ca. The isothermal section of the Ca-Mg-Zn phase diagram at 335 °C was constructed on the basis of the obtained experimental results. The morphologies of the diffusion couples in the Ca-Mg-Zn phase diagram at 335 °C were studied. Depending on the terminal compositions of the diffusion couples, the two-phase regions in the diffusion zone have either a tooth-like morphology or contain a matrix phase with isolated and/or dendritic precipitates.

Workshop on Microwave Power Transmission and Reception. Workshop Paper Summaries

NASA Technical Reports Server (NTRS)

1980-01-01

Microwave systems performance and phase control are discussed. Component design and reliability are highlighted. The power amplifiers, radiating elements, rectennas, and solid state configurations are described. The proper sizing of microwave transmission systems is also discussed.

Numerical Simulation of Combustion and Extinction of a Solid Cylinder in Low-Speed Cross Flow

NASA Technical Reports Server (NTRS)

Tien, J. S.; Yang, Chin Tien

1998-01-01

The combustion and extinction behavior of a diffusion flame around a solid fuel cylinder (PMMA) in low-speed forced flow in zero gravity was studied numerically using a quasi-steady gas phase model. This model includes two-dimensional continuity, full Navier Stokes' momentum, energy, and species equations with a one-step overall chemical reaction and second-order finite-rate Arrhenius kinetics. Surface radiation and Arrhenius pyrolysis kinetics are included on the solid fuel surface description and a parameter Phi, representing the percentage of gas-phase conductive heat flux going into the solid, is introduced into the interfacial energy balance boundary condition to complete the description for the quasi-steady gas-phase system. The model was solved numerically using a body-fitted coordinate transformation and the SIMPLE algorithm. The effects of varying freestream velocity and Phi were studied. These parameters have a significant effect on the flame structure and extinction limits. Two flame modes were identified: envelope flame and wake flame. Two kinds of flammability limits were found: quenching at low-flow speeds due to radiative loss and blow-off at high flow speeds due to insufficient gas residence time. A flammability map was constructed showing the existence of maximum Phi above which the solid is not flammable at any freestream velocity.

A unified momentum equation approach for computing thermal residual stresses during melting and solidification

NASA Astrophysics Data System (ADS)

Yeo, Haram; Ki, Hyungson

2018-03-01

In this article, we present a novel numerical method for computing thermal residual stresses from a viewpoint of fluid-structure interaction (FSI). In a thermal processing of a material, residual stresses are developed as the material undergoes melting and solidification, and liquid, solid, and a mixture of liquid and solid (or mushy state) coexist and interact with each other during the process. In order to accurately account for the stress development during phase changes, we derived a unified momentum equation from the momentum equations of incompressible fluids and elastoplastic solids. In this approach, the whole fluid-structure system is treated as a single continuum, and the interaction between fluid and solid phases across the mushy zone is naturally taken into account in a monolithic way. For thermal analysis, an enthalpy-based method was employed. As a numerical example, a two-dimensional laser heating problem was considered, where a carbon steel sheet was heated by a Gaussian laser beam. Momentum and energy equations were discretized on a uniform Cartesian grid in a finite volume framework, and temperature-dependent material properties were used. The austenite-martensite phase transformation of carbon steel was also considered. In this study, the effects of solid strains, fluid flow, mushy zone size, and laser heating time on residual stress formation were investigated.

Optimized formulation of solid self-microemulsifying sirolimus delivery systems

PubMed Central

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

2013-01-01

Background The aim of this study was to develop an optimized solid self-microemulsifying drug delivery system (SMEDDS) formulation for sirolimus to enhance its solubility, stability, and bioavailability. Methods Excipients used for enhancing the solubility and stability of sirolimus were screened. A phase-separation test, visual observation for emulsifying efficiency, and droplet size analysis were performed. Ternary phase diagrams were constructed to optimize the liquid SMEDDS formulation. The selected liquid SMEDDS formulations were prepared into solid form. The dissolution profiles and pharmacokinetic profiles in rats were analyzed. Results In the results of the oil and cosolvent screening studies, Capryol™ Propylene glycol monocapry late (PGMC) and glycofurol exhibited the highest solubility of all oils and cosolvents, respectively. In the surfactant screening test, D-α-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) was determined to be the most effective stabilizer of sirolimus in pH 1.2 simulated gastric fluids. The optimal formulation determined by the construction of ternary phase diagrams was the T32 (Capryol™ PGMC:glycofurol:vitamin E TPGS = 30:30:40 weight ratio) formulation with a mean droplet size of 108.2 ± 11.4 nm. The solid SMEDDS formulations were prepared with Sucroester 15 and mannitol. The droplet size of the reconstituted solid SMEDDS showed no significant difference compared with the liquid SMEDDS. In the dissolution study, the release amounts of sirolimus from the SMEDDS formulation were significantly higher than the raw sirolimus powder. In addition, the solid SMEDDS formulation was in a more stable state than liquid SMEDDS in pH 1.2 simulated gastric fluids. The results of the pharmacokinetic study indicate that the SMEDDS formulation shows significantly greater bioavailability than the raw sirolimus powder or commercial product (Rapamune® oral solution). Conclusion The results of this study suggest the potential use of a solid SMEDDS formulation for the delivery of poorly water-soluble drugs, such as sirolimus, through oral administration. PMID:23641156

Effect of water on foaming properties of diglycerol fatty acid ester-oil systems.

PubMed

Shrestha, Lok Kumar; Shrestha, Rekha Goswami; Solans, Conxita; Aramaki, Kenji

2007-06-19

We have studied the effect of added water on the nonaqueous foaming properties of diglycerol fatty acid ester nonionic surfactant systems. Diglycerol monomyristate (designated as DGM) could not foam in nonpolar oils squalane and hexadecane at normal room temperature. Nevertheless, addition of a small amount of water induces a dramatic change in foaming properties. Both the foamability and foam stability increases with the amount of added water within the studied concentration range. Phase behavior study showed that in the dilute regions there is dispersion of solid surfactant in the aforementioned oils in the DGM systems. The particle size of the dispersed solid phase was found to be several tens of microns in the water free system, and hence it tends to coagulate and precipitate. In the case of shorter alkyl chain length, diglycerol monolaurate (DGL) surfactant-oil systems, dispersion of lamellar liquid crystal (Lalpha) is observed at room temperature, and the poor foaming properties were attributed to the large particle size of the liquid crystal. In both the DGL and DGM-oil systems, we observed a tendency of the particle size to decrease with the increasing concentration of added water. At higher temperature, the solid surfactant transforms to lamellar liquid crystal phase, and foaming is improved in the DGM/squalane system. Foams are stable for several minutes. Judging from the foaming test and particle size distribution data it can be concluded that the poor foaming in the diglycerol fatty acid esters-oil systems may possibly be due to bigger particle size, which causes precipitation. Addition of water results in the dispersion of smaller particles and improves the foaming behavior.

Structural transformation in antiferroelectric PbZrO3-relaxor ferroelectric Pb(Ni1/3Nb2/3)O3 solid solution system

NASA Astrophysics Data System (ADS)

Wirunchit, S.; Vittayakorn, N.

2008-07-01

The solid solution between the antiferroelectric (AFE) PbZrO3 (PZ) and the relaxor ferroelectric (FE) Pb(Ni1/3Nb2/3)O3 (PNN) was synthesized by the columbite precursor method. The crystal structure, phase transformations, and dielectric and thermal properties of (1-x )PZ-xPNN where x =0.00-0.30 were investigated. With these data, the FE phase diagram between PZ and PNN has been established. The crystal structure data obtained from X-ray diffraction indicate that the solid solution PZ-PNN, where x =0.00-0.30, successively transforms from orthorhombic to rhombohedral symmetry with an increase in the PNN concentration. The AFE phase→FE phase transition occurs in compositions of 0.00⩽x⩽0.08. The AFE →FE phase transition shifts to lower temperatures with higher compositions of x. The FE phase temperature range width increases with increased PNN. Apparently the replacement of the Zr4+ ion by Ni2+/Nb5+ ions decreases the driving force for an antiparallel shift of Pb2+ ions because they interrupt the translational symmetry and facilitates the appearance of a rhombohedral FE phase when the amount of PNN is higher than 8mol%.

Structural and Mössbauer characterization of the ball milled Fe x(Cr 2O 3) 1- x system

NASA Astrophysics Data System (ADS)

Biondo, Valdecir; de Medeiros, Suzana Nóbrega; Paesano, Andrea, Jr.; Ghivelder, Luis; Hallouche, Bachir; da Cunha, João Batista Marimon

2009-08-01

The Fe x(Cr 2O 3) 1- x system, with 0.10 ≤ X ≤ 0.80, was mechanically processed for 24 h in a high-energy ball-mill. In order to examine the possible formation of iron-chromium oxides and alloys, the milled samples were, later, thermally annealed in inert (argon) and reducing (hydrogen) atmospheres. The as-milled and annealed products were characterized by X-ray diffraction, Mössbauer spectroscopy, transmission electron microscopy and magnetization. The as-milled samples showed the formation of an Fe 1+ YCr 2- YO 4- δ nanostructured and disordered spinel phase, the α 1-Fe(Cr) and α 2-Cr(Fe) solid solutions and the presence of non-exhausted precursors. For the samples annealed in inert atmosphere, the chromite (FeCr 2O 4) formation and the recrystallization of the precursors were verified. The hydrogen treated samples revealed the reduction of the spinel phase, with the phase separation of the chromia phase and retention of the Fe-Cr solid solutions. All the samples, either as-milled or annealed, presented the magnetization versus applied field curves typical for superparamagnetic systems.

Some Fundamental Experiments on Apparent Dissolution Rate of Gas Phase in the Groundwater Recovery Processes of the Geological Disposal System - 12146

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

Yoshii, Taiki; Niibori, Yuichi; Mimura, Hitoshi

The apparent dissolution rates of gas phase in the co-presence of solid phase were examined by in-room experiments in this study. The apparent dissolution rate of gas phase q (mol/m{sup 3}.s) was generally defined by q=aK{sub L}(γP{sub g}-c), where a (1/m) is specific surface area of the interface between gas and liquid phases, K{sub L} (m/s) is overall mass transfer coefficient, γ (mol/(Pa.m{sup 3})) is reciprocal number of Henry constant, P{sub g} (Pa) is partial pressure of gas phase, and c (mol/m{sup 3}) is the concentration of gas component in liquid phase. As a model gas, CO{sub 2} gas wasmore » used. For evaluating the values of K{sub L}, this study monitored pH or the migration rate of the interface between water/gas phases, using some experiments such as the packed beds and the micro channel consisting of granite chip and rubber sheet including a slit. In the results, the values of K{sub L} were distributed in the range from 5.0x10{sup -6} m/s to 5.0x10{sup -7} m/s. These values were small, in comparison with that (7.8x10{sup -4} m/s) obtained from the bubbling test where gas phase was continually injected into deionized water without solid phase. This means that the solid phase limits the local mixing of water phase near gas-liquid interfaces. (authors)« less

Precipitation in Al–Mg solid solution prepared by solidification under high pressure

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

Jie, J.C., E-mail: jiejc@dlut.edu.cn; School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001; Wang, H.W.

2014-01-15

The precipitation in Al–Mg solid solution containing 21.6 at.% Mg prepared by solidification under 2 GPa was investigated. The results show that the γ-Al{sub 12}Mg{sub 17} phase is formed and the β′ phase cannot be observed in the solid solution during ageing process. The precipitation of γ and β phases takes place in a non-uniform manner during heating process, i.e. the γ and β phases are first formed in the interdendritic region, which is caused by the inhomogeneous distribution of Mg atoms in the solid solution solidified under high pressure. Peak splitting of X-ray diffraction patterns of Al(Mg) solid solutionmore » appears, and then disappears when the samples are aged at 423 K for different times, due to the non-uniform precipitation in Al–Mg solid solution. The direct transformation from the γ to β phase is observed after ageing at 423 K for 24 h. It is considered that the β phase is formed through a peritectoid reaction of α + γ → β which needs the diffusion of Mg atoms across the interface of α/γ phases. - Highlights: • The γ phase is formed and the β′ phase is be observed in Al(Mg) solid solution. • Peak splitting of XRD pattern of Al(Mg) solid solution appears during aged at 150 °C. • The β phase is formed through a peritectoid reaction of α + γ → β.« less

Preparing, Characterizing, and Investigating Luminescent Properties of a Series of Long-Lasting Phosphors in a SrO-Al[subscript 2]O[subscript 3] System: An Integrated and Inquiry-Based Experiment in Solid State Chemistry for the Undergraduate Laboratory

ERIC Educational Resources Information Center

Ma, Yan-Zi; Jia, Li; Ma, Kai-Guo; Wang, Hai-Hong; Jing, Xi-Ping

2017-01-01

An integrated and inquiry-based experiment on solid state chemistry is applied to an inorganic chemistry lab course to provide insight into the characteristics of the solid phase reaction. In this experiment, students have the opportunity to synthesize long-lasting phosphors with formula xSrO·yAl[subscript 2]O[subscript 3]:Eu[superscript 2+],…

SPECTRAL AND MODE PROPERTIES OF SOLID-STATE LASERS AND OPTICAL DYNAMIC EFFECTS.

DTIC Science & Technology

LASERS , OPTICAL PROPERTIES), THERMAL PROPERTIES, FREQUENCY, RUBY, KERR CELLS, ELECTROMAGNETIC PULSES, PHASE LOCKED SYSTEMS, GARNET, NEODYMIUM, CAVITY RESONATORS, INTERFEROMETERS, LIGHT PULSES, PROPAGATION

Space cryogenics components based on the thermomechanical effect - Vapor-liquid phase separation

NASA Technical Reports Server (NTRS)

Yuan, S. W. K.; Frederking, T. H. K.

1989-01-01

Applications of the thermomechanical effect has been qualified including incorporation in large-scale space systems in the area of vapor-liquid phase separation (VLPS). The theory of the porous-plug phase separator is developed for the limit of a high thermal impedance of the solid-state grains. Extensions of the theory of nonlinear turbulent flow are presented based on experimental results.

Fuel spill identification using solid-phase extraction and solid-phase microextraction. 1. Aviation turbine fuels.

PubMed

Lavine, B K; Brzozowski, D M; Ritter, J; Moores, A J; Mayfield, H T

2001-12-01

The water-soluble fraction of aviation jet fuels is examined using solid-phase extraction and solid-phase microextraction. Gas chromatographic profiles of solid-phase extracts and solid-phase microextracts of the water-soluble fraction of kerosene- and nonkerosene-based jet fuels reveal that each jet fuel possesses a unique profile. Pattern recognition analysis reveals fingerprint patterns within the data characteristic of fuel type. By using a novel genetic algorithm (GA) that emulates human pattern recognition through machine learning, it is possible to identify features characteristic of the chromatographic profile of each fuel class. The pattern recognition GA identifies a set of features that optimize the separation of the fuel classes in a plot of the two largest principal components of the data. Because principal components maximize variance, the bulk of the information encoded by the selected features is primarily about the differences between the fuel classes.

The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2

USGS Publications Warehouse

Sharp, Z.D.; Essene, E.J.; Anovitz, Lawrence M.; Metz, G.W.; Westrum, E.F.; Hemingway, B.S.; Valley, J.W.

1986-01-01

The heat capacity of a natural monticellite (Ca1.00Mg.09Fe.91Mn.01Si0.99O3.99) measured between 9.6 and 343 K using intermittent-heating, adiabatic calorimetry yields Cp0(298) and S2980 of 123.64 ?? 0.18 and 109.44 ?? 0.16 J ?? mol-1 K-1 respectively. Extrapolation of this entropy value to end-member monticellite results in an S0298 = 108.1 ?? 0.2 J ?? mol-1 K-1. High-temperature heat-capacity data were measured between 340-1000 K with a differential scanning calorimeter. The high-temperature data were combined with the 290-350 K adiabatic values, extrapolated to 1700 K, and integrated to yield the following entropy equation for end-member monticellite (298-1700 K): ST0(J ?? mol-1 K-1) = S2980 + 164.79 In T + 15.337 ?? 10-3 T + 22.791 ?? 105 T-2 - 968.94. Phase equilibria in the CaO-MgO-SiO2 system were calculated from 973 to 1673 K and 0 to 12 kbar with these new data combined with existing data for akermanite (Ak), diopside (Di), forsterite (Fo), merwinite (Me) and wollastonite (Wo). The location of the calculated reactions involving the phases Mo and Fo is affected by their mutual solid solution. A best fit of the thermodynamically generated curves to all experiments is made when the S0298 of Me is 250.2 J ?? mol-1 K-1 less than the measured value of 253.2 J ?? mol-1 K-1. A best fit to the reversals for the solid-solid and decarbonation reactions in the CaO-MgO-SiO2-CO2 system was obtained with the ??G0298 (kJ ?? mole-1) for the phases Ak(-3667), Di(-3025), Fo(-2051), Me(-4317) and Mo(-2133). The two invariant points - Wo and -Fo for the solid-solid reactions are located at 1008 ?? 5 K and 6.3 ?? 0.1 kbar, and 1361 ?? 10 K and 10.2 ?? 0.2 kbar respectively. The location of the thermodynamically generated curves is in excellent agreement with most experimental data on decarbonation equilibria involving these phases. ?? 1986.

Lubricant-impregnated surfaces for electrochemical applications, and devices and systems using same

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

Solomon, Brian Richmond; Chen, Xinwei; Chiang, Yet-Ming

In certain embodiments, the invention relates to an electrochemical device having a liquid lubricant impregnated surface. At least a portion of the interior surface of the electrochemical device includes a portion that includes a plurality of solid features disposed therein. The plurality of solid features define a plurality of regions therebetween. A lubricant is disposed in the plurality of regions which retain the liquid lubricant in the plurality of regions during operation of the device. An electroactive phase comes in contact with at least the portion of the interior surface. The liquid lubricant impregnated surface introduces a slip at themore » surface when the electroactive phase flows along the surface. The electroactive phase may be a yield stress fluid.« less

Extensively Reversible Thermal Transformations of a Bistable, Fluorescence-Switchable Molecular Solid: Entry into Functional Molecular Phase-Change Materials.

PubMed

Srujana, P; Radhakrishnan, T P

2015-06-15

Functional phase-change materials (PCMs) are conspicuously absent among molecular materials in which the various attributes of inorganic solids have been realized. While organic PCMs are primarily limited to thermal storage systems, the amorphous-crystalline transformation of materials like Ge-Sb-Te find use in advanced applications such as information storage. Reversible amorphous-crystalline transformations in molecular solids require a subtle balance between robust supramolecular assembly and flexible structural elements. We report novel diaminodicyanoquinodimethanes that achieve this transformation by interlinked helical assemblies coupled with conformationally flexible alkoxyalkyl chains. They exhibit highly reversible thermal transformations between bistable (crystalline/amorphous) forms, along with a prominent switching of the fluorescence emission energy and intensity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid-solid phase change thermal storage application to space-suit battery pack

NASA Astrophysics Data System (ADS)

Son, Chang H.; Morehouse, Jeffrey H.

1989-01-01

High cell temperatures are seen as the primary safety problem in the Li-BCX space battery. The exothermic heat from the chemical reactions could raise the temperature of the lithium electrode above the melting temperature. Also, high temperature causes the cell efficiency to decrease. Solid-solid phase-change materials were used as a thermal storage medium to lower this battery cell temperature by utilizing their phase-change (latent heat storage) characteristics. Solid-solid phase-change materials focused on in this study are neopentyl glycol and pentaglycerine. Because of their favorable phase-change characteristics, these materials appear appropriate for space-suit battery pack use. The results of testing various materials are reported as thermophysical property values, and the space-suit battery operating temperature is discussed in terms of these property results.

Effect of structural phase transformation in FeGaO{sub 3} on its magnetic and ferroelectric properties

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

Lone, A. G., E-mail: agl221986@gmail.com; Bhowmik, R. N.

2015-06-24

We investigate the structural phase transformation from orthorhombic to rhombohedral structure in FeGaO{sub 3} by adopting a combined effect of mechanical alloying/milling and solid state sintering techniques. The structural phase formation of the FeGaO{sub 3} compound has been characterized by X-ray diffraction pattern. Mechanical milling played a significant role on the stabilization of rhombohedral phase in FeGaO{sub 3}, where as high temperature sintering stabilized the system in orthorhombic phase. A considerable difference has been observed in magnetic and ferroelectric properties of the system in two phases. The system in rhombohedral (R-3c) phase exhibited better ferromagnetic and of ferroelectric properties atmore » room temperature in comparison to orthorhombic (Pc2{sub 1}n) phase. The rhombohedral phase appears to be good for developing metal doped hematite system for spintronics applications and in that process mechanical milling played an important role.« less

Solubility relations in the system sodium chloride-ferrous chloride-water between 25 and 70.degree.C at 1 atm

USGS Publications Warehouse

Chou, I.-Ming; Phan, L.D.

1985-01-01

Solubility relations in the ternary system NaCl-FeCl2-H2O have been determined by the visual polythermal method at 1 atm from 20 to 85??C along six composition lines. These she composition lines are defined by mixing FeCl2??4H2O with six aqueous NaCl solutions containing 5, 10, 11, 15, 20, and 25 wt % of NaCl, respectively. The solid phases encountered in these experiments were NaCl and FeCl2??4H2O. The maximum uncertainties in these measurements are ??0.02 wt % NaCl and ??0.15??C. The data along each composition line were regressed to a smooth curve when only one solid phase was stable. When two solids were stable along a composition line, the data were regressed to two smooth curves, the intersection of which indicated the point where the two solids coexisted. The maximum deviation of the measured solubilities from the smoothed curves is 0.14 wt % FeCl2. Isothermal solubilities of halite and FeCl2??4H2O were calculated from these smoothed curves at 25, 50, and 70 ??C.

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

Vasilyeva, I.G., E-mail: kamarz@niic.nsc.r; Nikolaev, R.E.; Verozubova, G.A.

Abstracts: The nonstoichiometry of ZnGeP{sub 2} has been determined based on the p-T dependences measured above ZnP{sub 2}-Ge samples in the temperature range of 980-1225 K by a high-sensitive and precise tensimetric static method with a quartz Bourdon gauge. Scanning of the compositional range 49-51 mol% ZnP{sub 2} in the closed system and construction of the p-T dependences were possible due to incongruent evaporation of ZnGeP{sub 2} and formation of volatile species Zn(g), P{sub 4}(g) and P{sub 2}(g). The maximum homogeneity range of the solid ZnGeP{sub 2} was determined between 50.03 and 49.61 mol% ZnP{sub 2} at a temperature ofmore » 1128 K, based on the inflection points on the p-T dependences, corresponding to transitions of the three-phase (solid-solid-vapor) equilibrium to a two-phase (solid-vapor) one and vice visa. The nonstoichiometry as the overall concentration of defects is considered to gain a better insight into the defect chemistry of ZnGeP{sub 2}. - Graphical abstract: The nonstoichiometry of ZnGeP{sub 2} on the T-x diagram of the ZnP{sub 2}-Ge system.« less

Application of solid-phase microextraction with gas chromatography and mass spectrometry for the early detection of active moulds on historical woollen objects.

PubMed

Sawoszczuk, Tomasz; Syguła-Cholewińska, Justyna; Del Hoyo-Meléndez, Julio M

2017-02-01

The goal of this work was to determine the microbial volatile organic compounds emitted by moulds growing on wool in search of particular volatiles mentioned in the literature as indicators of active mould growth. The keratinolytically active fungi were inoculated on two types of media: (1) samples of wool placed on broths, and (2) on broths containing amino acids that are elements of the structure of keratin. All samples were prepared inside 20 mL vials (closed system). In the first case (1) the broths did not contain any sources of organic carbon, nitrogen, or sulfur, i.e. wool was the only nutrient for the moulds. A third type of sample was historical wool prepared in a Petri dish without a broth and inoculated with a keratinolytically active mould (open system). The microbial volatiles emitted by moulds were sampled with the headspace solid-phase microextraction method. Volatiles extracted on solid-phase microextraction fibers were analyzed in a gas chromatography with mass spectrometry system. Qualitative and quantitative analyses of chromatograms were carried out in search of indicators of metabolic activity. The results showed that there are three groups of volatiles that can be used for the detection of active forms of moulds on woollen objects. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PHASE DIAGRAM FOR THE SYSTEM TITANIUM-TIN (in Russian)

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

Kornilov, I.I.; Nartova, T.T.

1960-03-01

Differential thermal analysis, microstructural analyses, and determinations of hardness values and electric resistance were used to construct a diagram of state for the binary system Ti-Sn up to the composition of the compound Ti/sub 3/Sn (from 0 to 25 at.% Sn). Analyses of the thermograms showed that all conversions proceeding with the absorption of heat could be detected on the heating curves. Tin lowers the temperature of conversion of titunium with 5.0 at.% tin first to a minimum at 860 tained C which then increases to 890 tained C at higher tin contents. A peritectoid reaction ( alpha / submore » 2/ were ob ore resistant t + ) takes place with a conversion temperature at 890 tained C. A HF-HNO/sub 3/-glycerin etch showed a single-phase homogeneous structure of an alpha -solid solution with alloys containing up to 9 at.% Q. The amount of a second -phase increases with increasing tin content until a single-phase structure of a -solid solution of the compound Ti/sub 3/Sn is noted with alloys containing 23 to 25 at.% Sn. Alloys containing 8 to 22.5 at.% Sn undergo a peritectoid reaction, at a temperature of 890 tained C as shown by thermal analyses and by microstructural analyses of samples quenched frorn above and below the conversion temperature. A study of the microstructure of quenched alloys showed that the solubility of tin in ore resistant t -titanium increases from 8 at.% Sn at 890 tained C to 10.5 at.% Sn at 1100 tained C. X-ray analyses of annealed samples of alloy showed only the lines of an alpha solid solution for 5, 8, 9 at.% Sn, a -solid solution for 23 at.% Sn (close to the composition Ti/sub 3/Sn), and an alpha and mixed phase for a 15 at.% Sn. Vickers hardness numbers were determined with a diamond pyramid at a loading of 10 kg. The hardness increases smoothly with increasing tin content to a maximum at the saturation solubility of the tin in the alpha - or ore resistant t -solid solution. The hardness decreases smoothly with the appearance of the -phase until it attains a minimum at the composition of the compound Ti/sub 3/Sn. The specific electric resistance increases with an increase of tin in the solid solution of alpha -titanium. The rate of increase of the specific electric resistance decreases markedly with the appearance of the -phase. The electric resistance of an alloy with 14.3 at.% Sn was studied as a function of temperature from room temperature to 1100 tained C in special vacuum equipment. A sharp drop in electric resistance a; 890 tained C confirmed the existence of a peritectoid reaction in the system Ti-Sn. (TTT)« less

Pressure-induced fcc to hcp phase transition in Ni-based high entropy solid solution alloys

DOE PAGES

Zhang, Fuxiang; Zhao, Shijun; Jin, Ke; ...

2017-01-04

In this research, pressure-induced phase transition from the fcc to a hexagonal close-packed (hcp) structure wasfound in NiCoCrFe solid solution alloy starting at 13.5 GPa. The phase transition is very sluggish and the transition did not complete at ~ 40 GPa. The hcp structure is quenchable to ambient pressure. Only a very small amount (<5%) of hcp phase was found in the isostructural NiCoCr ternary alloy up to the pressure of 45 GPa and no obvious hcp phase was found in NiCoCrFePd system till to 74 GPa. Ab initio Gibbs free energy calculations indicated the energy differences between the fccmore » and the hcp phases for the three alloys are very small, but they are sensitive to temperature. Finally, the critical transition pressure in NiCoCrFe varies from 1 GPa at room temperature to 6 GPa at 500 K.« less

Pressure-induced fcc to hcp phase transition in Ni-based high entropy solid solution alloys

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

Zhang, F. X.; Zhao, Shijun; Jin, Ke

2017-01-04

A pressure-induced phase transition from the fcc to a hexagonal close-packed (hcp) structure was found in NiCoCrFe solid solution alloy starting at 13.5 GPa. The phase transition is very sluggish and the transition did not complete at ~40 GPa. The hcp structure is quenchable to ambient pressure. Only a very small amount (<5%) of hcp phase was found in the isostructural NiCoCr ternary alloy up to the pressure of 45 GPa and no obvious hcp phase was found in NiCoCrFePd system till to 74 GPa. Ab initio Gibbs free energy calculations indicated the energy differences between the fcc and themore » hcp phases for the three alloys are very small, but they are sensitive to temperature. The critical transition pressure in NiCoCrFe varies from ~1 GPa at room temperature to ~6 GPa at 500 K.« less

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

DOE PAGES

Gao, Jun; Manard, Benjamin Thomas; Castro, Alonso; ...

2017-02-02

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of ninemore » materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. Finally, the microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.« less

Phase diagram of Ag-Pd bimetallic nanoclusters by molecular dynamics simulations: solid-to-liquid transition and size-dependent behavior.

PubMed

Kim, Da Hye; Kim, Hyun You; Ryu, Ji Hoon; Lee, Hyuck Mo

2009-07-07

This report on the solid-to-liquid transition region of an Ag-Pd bimetallic nanocluster is based on a constant energy microcanonical ensemble molecular dynamics simulation combined with a collision method. By varying the size and composition of an Ag-Pd bimetallic cluster, we obtained a complete solid-solution type of binary phase diagram of the Ag-Pd system. Irrespective of the size and composition of the cluster, the melting temperature of Ag-Pd bimetallic clusters is lower than that of the bulk state and rises as the cluster size and the Pd composition increase. Additionally, the slope of the phase boundaries (even though not exactly linear) is lowered when the cluster size is reduced on account of the complex relations of the surface tension, the bulk melting temperature, and the heat of fusion. The melting of the cluster initially starts at the surface layer. The initiation and propagation of a five-fold icosahedron symmetry is related to the sequential melting of the cluster.

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

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

Gao, Jun; Manard, Benjamin Thomas; Castro, Alonso

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of ninemore » materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. Finally, the microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.« less

Hybrid propulsion technology program: Phase 1, volume 4

NASA Technical Reports Server (NTRS)

Claflin, S. E.; Beckman, A. W.

1989-01-01

The use of a liquid oxidizer-solid fuel hybrid propellant combination in booster rocket motors appears extremely attractive due to the integration of the best features of liquid and solid propulsion systems. The hybrid rocket combines the high performance, clean exhaust, and safety of liquid propellant engines with the low cost and simplicity of solid propellant motors. Additionally, the hybrid rocket has unique advantages such as an inert fuel grain and a relative insensitivity to fuel grain and oxidizer injection anomalies. The advantages mark the hybrid rocket as a potential replacement or alternative for current and future solid propellant booster systems. The issues are addressed and recommendations are made concerning oxidizer feed systems, injectors, and ignition systems as related to hybrid rocket propulsion. Early in the program a baseline hybrid configuration was established in which liquid oxygen would be injected through ports in a solid fuel whose composition is based on hydroxyl terminated polybutadiene (HTPB). Liquid oxygen remained the recommended oxidizer and thus all of the injector concepts which were evaluated assumed only liquid would be used as the oxidizer.

Solid phase graft copolymerization of acrylic monomers onto thermoplastics and their use as blend compatibilizers

NASA Astrophysics Data System (ADS)

Subramanian, Srinivas

This research work is an extension of some of the earlier work done on the development of solid phase grafting technique to graft various monomers onto polymers as well as postulation of the usefulness of the graft copolymers thus synthesized. Polystyrene grafted with acrylic acid, previously developed in bench scale, was synthesized in pilot-plant scale batches. Process parameter studies on the grafting of acrylic acid onto polypropylene and developmental studies on the grafting of maleic anhydride onto polystyrene were also done. Polymers grafted with polar molecules such as maleic anhydride and acrylic acid have been used to compatibilize immiscible blends of polar and non-polar polymers. On the same note, the applicability of the solid phase graft copolymers as blend compatibilizers were investigated and their performance was compared to commercially available compatibilizers. Solid phase graft copolymerization process is a technique to synthesize graft copolymers. Some of its salient features are use of minimal solvent to conduct the reaction and easy equipment modification. It is a low pressure and low temperature process. This technique provides a viable alternative to the environmentally hazardous, and time consuming conventional process currently in use. Hence, development of this technique could be beneficial not only to the plastics industry, but also to mankind. Also, this technique provides a low-cost and extremely easy method to develop graft copolymers such as acrylic acid functionalized polymers that are rapidly gaining popularity as blend compatibilizers and polymer reinforcing agents. A study that proves the potential of these solid phase graft copolymers as good blend compatibilizers for industrially important immiscible polymers will develop interest in the industries about this grafting process. The free radical solid phase graft copolymerization process was carried in a modified Brabender-type mixer fitted with specially designed blades to promote efficient mixing of the polymer, initiator, monomer, and solvent. The grafting was qualitatively confirmed by means of a FTIR and quantitatively using titration. The polymer blends were synthesized in a single screw extruder. Rheological, morphological, thermal, mechanical, and molecular weight studies were done on these blends. The graft copolymers produced in larger batches had the same amount of graft content as those produced in smaller batches. This small success is a positive step towards the goal of commercializing this process. Grafting of acrylic acid onto polypropylene gave graft levels of 4 weight percent. However, the attempt to graft maleic anhydride onto polystyrene was not successful. The solid phase graft copolymers were successfully able to compatibilize the polymer blend systems studied (PS/PMMA, PS/nylon 6,6, PS/nylon 6, and PP/nylon 6). The properties of the blends compatibilized using the solid phase graft copolymers were comparable to and in some instances, better than those of the blends compatibilized with commercially available graft copolymers. The successful scale-up of the process, development of new graft copolymers and ability of copolymers to compatibilize blends augurs well for the solid phase grafting process.

Characterization of a water-solid interaction in a partially ordered system.

PubMed

Chakravarty, Paroma; Lubach, Joseph W

2013-11-04

GNE068-PC, a developmental compound, was previously characterized to be mesomorphous, i.e. having long-range order associated with significant local molecular disorder (Chakravarty et. al., Mol. Pharmaceutics, accepted). The compound was exposed to moisture under different relative humidity conditions ranging from 11% to 60% RH at room temperature (RT) for 7 days, and the resultant product phases were characterized. The partially ordered sample progressively lost crystallinity (long-range order) and birefringence (orientational order) upon exposure to increasing RH conditions, leading to the formation of a completely disordered amorphous phase at 60% RH (RT). Long-range positional order was irrecoverable even after moisture removal from the sample exposed to 60% RH. This was attributed to replacement of residual ethyl acetate by water, the former being critical for maintenance of long-range order in the material. In addition, water sorption appeared to irreversibly alter the molecular orientation, thereby affecting sample birefringence. Solid-state NMR revealed increases in (1)H and (13)C spin-lattice relaxation times (T1) going from the mesomorphous phase to the fully amorphous phase. This was indicative of reduction in lattice mobility, likely due to the decreased motion of the aromatic portions of the molecule, in particular C17, which showed the most dramatic increase in (13)C T1. This is likely due to decrease in available free volume upon water sorption. Drying of the hydrated disordered phase showed somewhat greater mobility than the hydrated phase, likely due to increased relative free volume through removal of water. A water-solid interaction therefore irreversibly changed the solid-state makeup of GNE068-PC.

Determination of local values of gas and liquid mass flux in highly loaded two-phase flow

NASA Technical Reports Server (NTRS)

Burick, R. J.; Scheuerman, C. H.; Falk, A. Y.

1974-01-01

A measurement system using a deceleration probe was designed for determining the local values of gas and liquid mass flux in various gas/liquid droplet sprayfields. The system was used to characterize two-phase flowfields generated by gas/liquid rocket-motor injectors. Measurements were made at static pressures up to 500 psia and injected mass flow ratios up to 20. The measurement system can also be used at higher pressures and in gas/solid flowfields.

Crystallization process

DOEpatents

Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

1986-01-01

An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

MERCURY REACTIONS IN THE PRESENCE OF CHLORINE SPECIES: HOMOGENOUS GAS PHASE AND HETEROGENOUS GAS-SOLID PHASE

EPA Science Inventory

The kinetics of mercury chlorination (with HC1) were studied using a flow reactor system with an on-line Hg analyzer and spciation sampling using a set of impingers. Kinetic parameters, such as reaction order (a), activation energy (Eu) and the overall rate constant (k') were es...

Rigorous Mathematical Modeling of Adsorption System with Electrothermal Regeneration of the Used Adsorbent

DTIC Science & Technology

2006-12-01

DISTRIBUTION STATEMENT. ________//signature//________________ ________//signature//________________ PATRICK D. SULLIVAN, Ph.D., P.E. SANDRA R ...adsorber, at r =1.24 cm: (a) gas phase; (b) solid phase..................................................................................... 30 46 The...34 57 Axial profiles of the gas velocity during adsorption in the 2-cartridge adsorber at r =1.25cm..... 34 60

Multiphase Dynamics of Magma Oceans

NASA Astrophysics Data System (ADS)

Boukaré, Charles-Edouard; Ricard, Yanick; Parmentier, Edgar M.

2017-04-01

Since the earliest study of the Apollo lunar samples, the magma ocean hypothesis has received increasing consideration for explaining the early evolution of terrestrial planets. Giant impacts seem to be able to melt significantly large planets at the end of their accretion. The evolution of the resulting magma ocean would set the initial conditions (thermal and compositionnal structure) for subsequent long-term solid-state planet dynamics. However, magma ocean dynamics remains poorly understood. The major challenge relies on understanding interactions between the physical properties of materials (e.g., viscosity (at liquid or solid state), buoyancy) and the complex dynamics of an extremely vigorously convecting system. Such complexities might be neglected in cases where liquidus/adiabat interactions and density stratification leads to stable situations. However, interesting possibilities arise when exploring magma ocean dynamics in other regime. In the case of the Earth, recent studies have shown that the liquidus might intersect the adiabat at mid-mantle depth and/or that solids might be buoyant at deep mantle conditions. These results require the consideration of more sophisticated scenarios. For instance, how does bottom-up crystallization look with buoyant crystals? To understand this complex dynamics, we develop a multiphase phase numerical code that can handle simultaneously phase change, the convection in each phase and in the slurry, as well as the compaction or decompaction of the two phases. Although our code can only run in a limited parameter range (Rayleigh number, viscosity contrast between phases, Prandlt number), it provides a rich dynamics that illustrates what could have happened. For a given liquidus/adiabat configuration and density contrast between melt and solid, we explore magma ocean scenarios by varying the relative timescales of three first order processes: solid-liquid separation, thermo-chemical convective motions and magma ocean cooling.

A review on development of solid phase microextraction fibers by sol-gel methods and their applications.

PubMed

Kumar, Ashwini; Gaurav; Malik, Ashok Kumar; Tewary, Dhananjay Kumar; Singh, Baldev

2008-03-03

Solid phase microextraction (SPME) is an innovative, solvent free technology that is fast, economical and versatile. SPME is a fiber coated with a liquid (polymer), a solid (sorbent) or a combination of both. The fiber coating takes up the compounds from the sample by absorption in the case of liquid coatings or adsorption in the case of solid coatings. The SPME fiber is then transferred with the help of a syringe like device into the analytical instrument for desorption and analysis of the target analytes. The sol-gel process provides a versatile method to prepare size, shape and charge selective materials of high purity and homogeneity by means of preparation techniques different from the traditional ones, for the chemical analysis. This review is on the current state of the art and future trends in the developments of solid phase microextraction (SPME) fibers using sol-gel method. To achieve more selective determination of different compound classes, the variety of different coating material for SPME fibers has increased. Further developments in SPME as a highly efficient extraction technique, will greatly depend on new breakthroughs in the area of new coating material developments for the SPME fibers. In sol-gel approach, appropriate sol-gel precursors and other building blocks can be selected to create a stationary phase with desired structural and surface properties. This approach is efficient in integrating the advantageous properties of organic and inorganic material systems and thereby increasing and improving the extraction selectivity of the produced amalgam organic-inorganic stationary phases. This review is mainly focused on recent advanced developments in the design, synthesis, characterisation, properties and application of sol-gel in preparation of coatings for the SPME fibers.

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.

Comparison of HPMC based polymers performance as carriers for manufacture of solid dispersions using the melt extruder.

PubMed

Ghosh, Indrajit; Snyder, Jennifer; Vippagunta, Radha; Alvine, Marilyn; Vakil, Ronak; Tong, Wei-Qin; Vippagunta, Sudha

2011-10-31

Preparation of amorphous solid dispersions using hot-melt extrusion process for poorly water soluble compounds which degrade on melting remains a challenge due to exposure to high temperatures. The aim of this study was to develop a physically and chemically stable amorphous solid dispersion of a poorly water-soluble compound, NVS981, which is highly thermal sensitive and degrades upon melting at 165 °C. Hydroxypropyl Methyl Cellulose (HPMC) based polymers; HPMC 3cps, HPMC phthalate (HPMCP) and HPMC acetyl succinate (HPMCAS) were selected as carriers to prepare solid dispersions using hot melt extrusion because of their relatively low glass transition temperatures. The solid dispersions were compared for their ease of manufacturing, physical stability such as recrystallization potential, phase separation, molecular mobility and enhancement of drug dissolution. Two different drug loads of 20 and 50% (w/w) were studied in each polymer system. It was interesting to note that solid dispersions with 50% (w/w) drug load were easier to process in the melt extruder compared to 20% (w/w) drug load in all three carriers, which was attributed to the plasticizing behavior of the drug substance. Upon storage at accelerated stability conditions, no phase separation was observed in HPMC 3cps and HPMCAS solid dispersions at the lower and higher drug load, whereas for HPMCP, phase separation was observed at higher drug load after 3 months. The pharmaceutical performance of these solid dispersions was evaluated by studying drug dissolution in pH 6.8 phosphate buffer. Drug release from solid dispersion prepared from polymers used for enteric coating, i.e. HPMCP and HPMCAS was faster compared with the water soluble polymer HPMC 3cps. In conclusion, of the 3 polymers studied for preparing solid dispersions of thermally sensitive compound using hot melt extrusion, HPMCAS was found to be the most promising as it was easily processible and provided stable solid dispersions with enhanced dissolution. Copyright © 2011 Elsevier B.V. All rights reserved.

Dramatically different kinetics and mechanism at solid/liquid and solid/gas interfaces for catalytic isopropanol oxidation over size-controlled platinum nanoparticles.

PubMed

Wang, Hailiang; Sapi, Andras; Thompson, Christopher M; Liu, Fudong; Zherebetskyy, Danylo; Krier, James M; Carl, Lindsay M; Cai, Xiaojun; Wang, Lin-Wang; Somorjai, Gabor A

2014-07-23

We synthesize platinum nanoparticles with controlled average sizes of 2, 4, 6, and 8 nm and use them as model catalysts to study isopropanol oxidation to acetone in both the liquid and gas phases at 60 °C. The reaction at the solid/liquid interface is 2 orders of magnitude slower than that at the solid/gas interface, while catalytic activity increases with the size of platinum nanoparticles for both the liquid-phase and gas-phase reactions. The activation energy of the gas-phase reaction decreases with the platinum nanoparticle size and is in general much higher than that of the liquid-phase reaction which is largely insensitive to the size of catalyst nanoparticles. Water substantially promotes isopropanol oxidation in the liquid phase. However, it inhibits the reaction in the gas phase. The kinetic results suggest different mechanisms between the liquid-phase and gas-phase reactions, correlating well with different orientations of IPA species at the solid/liquid interface vs the solid/gas interface as probed by sum frequency generation vibrational spectroscopy under reaction conditions and simulated by computational calculations.

A novel DNA/histone H4 peptide complex detects autoantibodies in systemic lupus erythematosus sera.

PubMed

Panza, Filomena; Alcaro, Maria Claudia; Petrelli, Fiorella; Angelotti, Francesca; Pratesi, Federico; Rovero, Paolo; Migliorini, Paola

2016-10-04

The detection of anti-dsDNA antibodies is critical for the diagnosis and follow-up of systemic lupus erythematosus (SLE) patients. The presently available assays are characterized by a non-optimal specificity (solid phase assays) or sensitivity (Crithidia Luciliae immunofluorescence test (CLIFT)). To overcome the limits of CLIFT and solid phase chromatin assays, we explored the diagnostic potential of an assay based on plasmid DNA containing a highly bent fragment of 211 bp from Crithidia Luciliae minicircles, complexed with histone peptides. Electrically neutral complexes of PK201/CAT plasmid (PK) DNA and histone 4 (H4) peptides were evaluated by electromobility shift assay. Complexes of H4 peptides and PK were absorbed to the solid phase to detect specific immunoglobulin G (IgG) in sera. Sera from 109 SLE patients, 100 normal healthy subjects, and 169 disease controls were tested. H4(14-34) containing the consensus sequence for DNA binding interacts with PK, retarding its migration. H4(14-34)/PK complexes were used to test sera by ELISA. Anti-H4-PK antibodies were detected in 56 % of SLE sera (more frequently in patients with skin or joint involvement) versus 5.9 % in disease controls; inhibition assays show that sera react with epitopes present on DNA or on the complex, not on the peptide. Antibody titer is correlated with European Consensus Lupus Activity Measurement (ECLAM) score and anti-complement component 1q (C1q) antibodies, negatively with C3 levels. Anti-H4-PK antibodies compared with CLIFT and solid phase dsDNA assays display moderate concordance. The H4/PK assay is a simple and reliable test which is useful for the differential diagnosis and evaluation of disease activity in SLE patients.

Solidification and solid-state transformation sciences in metals additive manufacturing

DOE PAGES

Kirka, Michael M.; Nandwana, Peeyush; Lee, Yousub; ...

2017-02-11

Additive manufacturing (AM) of metals is rapidly emerging as an established manufacturing process for metal components. Unlike traditional metals fabrication processes, metals fabricated via AM undergo localized thermal cycles during fabrication. As a result, AM presents the opportunity to control the liquid-solid phase transformation, i.e. material texture. But, thermal cycling presents challenges from the standpoint of solid-solid phase transformations. We will discuss the opportunities and challenges in metals AM in the context of texture control and associated solid-solid phase transformations in Ti-6Al-4V and Inconel 718.

Geochemical Modeling of Reactions and Partitioning of Trace Metals and Radionuclides during Titration of Contaminated Acidic Sediments

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

Zhang, Fan; Parker, Jack C.; Luo, Wensui

2008-01-01

Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This study was undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cationmore » exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO{sub 4}{sup 2-} for contaminated sediments indicated close agreement, suggesting that the model could potentially be used to predict the acid-base behavior of the sediment-solution system under variable pH conditions.« less

Extinguishment of a Diffusion Flame Over a PMMA Cylinder by Depressurization in Reduced-Gravity

NASA Technical Reports Server (NTRS)

Goldmeer, Jeffrey Scott

1996-01-01

Extinction of a diffusion flame burning over horizontal PMMA (Polymethyl methacrylate) cylinders in low-gravity was examined experimentally and via numerical simulations. Low-gravity conditions were obtained using the NASA Lewis Research Center's reduced-gravity aircraft. The effects of velocity and pressure on the visible flame were examined. The flammability of the burning solid was examined as a function of pressure and the solid-phase centerline temperature. As the solid temperature increased, the extinction pressure decreased, and with a centerline temperature of 525 K, the flame was sustained to 0.1 atmospheres before extinguishing. The numerical simulation iteratively coupled a two-dimensional quasi-steady, gas-phase model with a transient solid-phase model which included conductive heat transfer and surface regression. This model employed an energy balance at the gas/solid interface that included the energy conducted by the gas-phase to the gas/solid interface, Arrhenius pyrolysis kinetics, surface radiation, and the energy conducted into the solid. The ratio of the solid and gas-phase conductive fluxes Phi was a boundary condition for the gas-phase model at the solid-surface. Initial simulations modeled conditions similar to the low-gravity experiments and predicted low-pressure extinction limits consistent with the experimental limits. Other simulations examined the effects of velocity, depressurization rate and Phi on extinction.

SOLID-LIQUID PHASE TRANSFER CATALYZED SYNTHESIS OF CINNAMYL ACETATE-KINETICS AND ANALYSIS OF FACTORS AFFECTING THE REACTION IN A BATCH REACTOR

EPA Science Inventory

The use of solid-liquid phase transfer catalysis has an advantage of carrying out reaction between two immiscible substrates, one in solid phase and the other in liquid phase, with high selectivity and at relatively low temperatures. In this study we investigated the synthesis ci...

Physicochemical properties and solubility of alkyl-(2-hydroxyethyl)-dimethylammonium bromide.

PubMed

Domańska, Urszula; Bogel-Łukasik, Rafał

2005-06-23

Quaternary ammonium salts, which are precursors of ionic liquids, have been prepared from N,N-dimethylethanolamine as a substrate. The paper includes specific basic characterization of synthesized compounds via the following procedures: nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectra, water content, mass spectroscopy (MS) spectra, temperatures of decompositions, basic thermodynamic properties of pure ionic liquids (the melting point, enthalpy of fusion, enthalpy of solid-solid phase transition, glass transition), and the difference in the solute heat capacity between the liquid and solid at the melting temperature determined by differential scanning calorimetry (DSC). The (solid + liquid) phase equilibria of binary mixtures containing (quaternary ammonium salt + water, or + 1-octanol) has been measured by a dynamic method over wide range of temperatures, from 230 K to 560 K. These data were correlated by means of the UNIQUAC ASM and modified nonrandom two-liquid NRTL1 equations utilizing parameters derived from the (solid + liquid) equilibrium. The partition coefficient of ionic liquid in the 1-octanol/water binary system has been calculated from the solubility results. Experimental partition coefficients (log P) were negative at three temperatures.

A Binary Solid-Liquid Phase Diagram Experiment Including Determination of Purity, Enthalpy of Fusion and True Melting Point.

ERIC Educational Resources Information Center

Meyer, Edwin F.; Meyer, Joseph A.

1980-01-01

Describes an experiment as an alternative to undergraduate experiments limited to high temperature metal systems or lower temperature systems involving objectionable or unstable materials. Lists six advantages of the experiment. (Author/JN)

Clustering and phase behaviour of attractive active particles with hydrodynamics.

PubMed

Navarro, Ricard Matas; Fielding, Suzanne M

2015-10-14

We simulate clustering, phase separation and hexatic ordering in a monolayered suspension of active squirming disks subject to an attractive Lennard-Jones-like pairwise interaction potential, taking hydrodynamic interactions between the particles fully into account. By comparing the hydrodynamic case with counterpart simulations for passive and active Brownian particles, we elucidate the relative roles of self-propulsion, interparticle attraction, and hydrodynamic interactions in determining clustering and phase behaviour. Even in the presence of an attractive potential, we find that hydrodynamic interactions strongly suppress the motility induced phase separation that might a priori have been expected in a highly active suspension. Instead, we find only a weak tendency for the particles to form stringlike clusters in this regime. At lower activities we demonstrate phase behaviour that is broadly equivalent to that of the counterpart passive system at low temperatures, characterized by regimes of gas-liquid, gas-solid and liquid-solid phase coexistence. In this way, we suggest that a dimensionless quantity representing the level of activity relative to the strength of attraction plays the role of something like an effective non-equilibrium temperature, counterpart to the (dimensionless) true thermodynamic temperature in the passive system. However there are also some important differences from the equilibrium case, most notably with regards the degree of hexatic ordering, which we discuss carefully.

An experimental and theoretical evaluation of increased thermal diffusivity phase change devices

NASA Technical Reports Server (NTRS)

White, S. P.; Golden, J. O.; Stermole, F. J.

1972-01-01

This study was to experimentally evaluate and mathematically model the performance of phase change thermal control devices containing high thermal conductivity metal matrices. Three aluminum honeycomb filters were evaluated at five different heat flux levels using n-oct-adecane as the test material. The system was mathematically modeled by approximating the partial differential equations with a three-dimensional implicit alternating direction technique. The mathematical model predicts the system quite well. All of the phase change times are predicted. The heating of solid phase is predicted exactly while there is some variation between theoretical and experimental results in the liquid phase. This variation in the liquid phase could be accounted for by the fact that there are some heat losses in the cell and there could be some convection in the experimental system.

Barium isotope fractionation during witherite (BaCO3) dissolution, precipitation and at equilibrium

NASA Astrophysics Data System (ADS)

Mavromatis, Vasileios; van Zuilen, Kirsten; Purgstaller, Bettina; Baldermann, Andre; Nägler, Thomas F.; Dietzel, Martin

2016-10-01

This study examines the behavior of Ba isotope fractionation between witherite and fluid during mineral dissolution, precipitation and at chemical equilibrium. Experiments were performed in batch reactors at 25 °C in 10-2 M NaCl solution where the pH was adjusted by continuous bubbling of a water saturated gas phase of CO2 or atmospheric air. During witherite dissolution no Ba isotope fractionation was observed between solid and fluid. In contrast, during witherite precipitation, caused by a pH increase, a preferential uptake of the lighter 134Ba isotopomer in the solid phase was observed. In this case, the isotope fractionation factor αwitherite-fluid is calculated to be 0.99993 ± 0.00004 (or Δ137/134Bawitherite-fluid ≈ -0.07 ± 0.04‰, 2 sd). The most interesting feature of this study, however, is that after the attainment of chemical equilibrium, the Ba isotope composition of the aqueous phase is progressively becoming lighter, indicating a continuous exchange of Ba2+ ions between witherite and fluid. Mass balance calculations indicate that the detachment of Ba from the solid is not only restricted to the outer surface layer of the solid, but affects several (∼7 unit cells) subsurface layers of the crystal. This observation comes in excellent agreement with the concept of a dynamic system at chemical equilibrium in a mineral-fluid system, denoting that the time required for the achievement of isotopic equilibrium in the witherite-fluid system is longer compared to that observed for chemical equilibrium. Overall, these results indicate that the isotopic composition of Ba bearing carbonates in natural environments may be altered due to changes in fluid composition without a net dissolution/precipitation to be observed.

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.

Bound acoustic modes in the radiation continuum in isotropic layered systems without periodic structures

NASA Astrophysics Data System (ADS)

Maznev, A. A.; Every, A. G.

2018-01-01

We study the existence of guided acoustic modes in layered structures whose phase velocity is higher than that of bulk waves in a solid substrate or an adjacent fluid half space, which belong to the class of bound states in the radiation continuum (BICs). We demonstrate that in contrast to the electromagnetic case, non-symmetry-protected BICs exist in isotropic layered systems without periodic structures. Two systems supporting non-symmetry-protected sagittally polarized BICs have been identified: (i) a supported solid layer yields BICs whose phase velocity is higher than the transverse velocity of the substrate but lower than the longitudinal velocity; (ii) a supported solid layer loaded by a fluid half space supports BICs whose velocity is higher that the bulk velocity of the fluid but lower than acoustic velocities of the substrate. The latter case is a unique example of BICs in the sense that it does not involve an evanescent field in the fluid half space providing the radiation continuum. In either case, BICs are represented by isolated points in the dispersion relations located within "leaky" branches. We show that these BICs are robust with respect to small perturbations of the system parameters. Numerical results are provided for realistic materials combinations. We also show that no BICs exist in all-fluid layered structures, whereas in solid layered structures there are no shear horizontal BICs and no sagittally polarized BICs whose velocity exceeds the longitudinal velocity of the substrate.

The influence of precipitation kinetics on trace element partitioning between solid and liquid solutions: A coupled fluid dynamics/thermodynamics framework to predict distribution coefficients

NASA Astrophysics Data System (ADS)

Kavner, A.

2017-12-01

In a multicomponent multiphase geochemical system undergoing a chemical reaction such as precipitation and/or dissolution, the partitioning of species between phases is determined by a combination of thermodynamic properties and transport processes. The interpretation of the observed distribution of trace elements requires models integrating coupled chemistry and mechanical transport. Here, a framework is presented that predicts the kinetic effects on the distribution of species between two reacting phases. Based on a perturbation theory combining Navier-Stokes fluid flow and chemical reactivity, the framework predicts rate-dependent partition coefficients in a variety of different systems. We present the theoretical framework, with applications to two systems: 1. species- and isotope-dependent Soret diffusion of species in a multicomponent silicate melt subjected to a temperature gradient, and 2. Elemental partitioning and isotope fractionation during precipitation of a multicomponent solid from a multicomponent liquid phase. Predictions will be compared with results from experimental studies. The approach has applications for understanding chemical exchange in at boundary layers such as the Earth's surface magmatic systems and at the core/mantle boundary.

Three-Man Solid Electrolyte Carbon Dioxide Electrolysis Breadboard

NASA Technical Reports Server (NTRS)

Isenberg, Arnold O.

1989-01-01

The development of the Three-Man (2.2 lb CO2/man-day) Solid Electrolyte CO2 Electrolysis Breadboard consisted of a Phase 1 and 2 effort. The Phase 1 effort constituted fabrication of three electrolysis cell types and performing parametric testing, off-design testing, and cell life testing. The Phase 2 consisted of the preliminary design, incorporation of palladium (Pd) tubes for hydrogen separation from the electrolyzer cathode feed gases, design support testing, final design, fabrication, and performance testing of the breadboard system. The results of performance tests demonstrated that CO2 electrolysis in an oxygen reclamation system for long duration space-based habitats is feasible. Closure of the oxygen system loop, therefore, can be achieved by CO2 electrolysis. In a two step process the metabolic CO2 and H2O vapor are electrolyzed into O2, H2, and CO. The CO can subsequently be disproportionated into carbon and CO2 in a carbon deposition reactor and the CO2 in turn be recycled and electrolyzed for total O2 recovery. The development effort demonstrated electrolyzer system can be designed and built to operate safely and reliably and the incorporation of Pd tubes for hydrogen diffusion can be integrated safely with predictable performance.

Structural, dielectric and impedance characteristics of lanthanum-modified BiFeO3-PbTiO3 electronic system

NASA Astrophysics Data System (ADS)

Pradhan, S. K.; Das, S. N.; Bhuyan, S.; Behera, C.; Padhee, R.; Choudhary, R. N. P.

2016-06-01

A lanthanum-modified BiFeO3-PbTiO3 binary electronic system has been fabricated by a high-temperature solid-state reaction technique. The structural, dielectric and electrical properties of a single phase of multicomponent system are investigated to understand its ferroelectrics as well as relaxation behavior. The X-ray diffraction structural analysis substantiates the formation of a new stable phase of tetragonal system (with a large c/a ratio 1.23) without any trace of impurity phase. The electrical behavior of the processed material is characterized through impedance spectroscopy in a wide frequency range (1 kHz-1 MHz) over a temperature range of 25-500 °C. It is observed that the substitution of lanthanum-modified PbTiO3 (PT) into BiFeO3 (BFO) reveals enviable multiferroic property which is evident from the ME coefficient measurement and ferroelectric loop. It also reduces the electrical leakage current or tangent loss. The ac conductivity of the solid solution increases with increase in frequency in the low-temperature region. The impedance spectroscopy of the synthesized material reflects the dielectric relaxation of non-Debye type.

[State of Fungal Lipases of Rhizopus microsporus, Penicillium sp. and Oospora lactis in Border Layers Water-Solid Phase and Factors Affecting Catalytic Properties of Enzymes].

PubMed

Khasanov, Kh T; Davranov, K; Rakhimov, M M

2015-01-01

We demonstrated that a change in the catalytic activity of fungal lipases synthesized by Rhizopus microsporus, Penicillium sp. and Oospora lactis and their ability to absorb on different sorbents depended on the nature of groups on the solid phase surface in the model systems water: lipid and water: solid phase. Thus, the stability of Penicillium sp. lipases increased 85% in the presence ofsorsilen or DEAE-cellulose, and 55% of their initial activity respectively was preserved. In the presence of silica gel and CM-cellulose, a decreased rate of lipid hydrolysis by Pseudomonas sp. enzymes was observed in water medium, and the hydrolysis rate increased by 2.4 and 1.5 times respectively in the presence of aminoaerosil and polykefamid. In an aqueous-alcohol medium, aminoaerosil and polykefamid decreased the rate of substrate hydrolysis by more than 30 times. The addition of aerosil to aqueous and aqueous-alcohol media resulted in an increase in the hydrolysis rate by 1.2-1.3 times. Sorsilen stabilized Penicillium sp. lipase activity at 40, 45, 50 and 55 degrees C. Either stabilization or inactivation of lipases was observed depending on the pH of the medium and the nature of chemical groups localized on the surface of solid phase. The synthetizing activity of lipases also changed depending on the conditions.

Eutectic, monotectic and immiscibility systems of nimesulide with water-soluble carriers: phase equilibria, solid-state characterisation and in-vivo/pharmacodynamic evaluation.

PubMed

Abdelkader, Hamdy; Abdallah, Ossama Y; Salem, Hesham; Alani, Adam W G; Alany, Raid G

2014-10-01

The solid-state interactions of fused mixtures nimesulide (ND) with polyethylene glycol (PEG) 4000, urea or mannitol were studied through constructing thaw-melt phase equilibrium diagrams. The solid-state characteristics were investigated using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Various types of interactions were identified such as the formation of a eutectic system of ND-PEG 4000, monotectic system of ND-urea and complete solid immiscibility of ND with mannitol. The effects of carrier concentrations on the equilibrium solubility and in-vitro dissolution characteristics were studied. Linear increases (R(2)  > 0.99) in the aqueous solubility of ND in various concentrations of PEG 4000 and urea were obtained, whereas mannitol did not exhibit any effect on the solubility of ND. Similar trends were obtained with the dissolution efficiency of the fused mixtures of ND with PEG 4000 and urea compared with the corresponding physical mixtures and untreated drug. The analgesic effects of untreated ND and the selected formulations were investigated by evaluating the drug's ability to inhibit the acetic acid-induced writhing response. The analgesic effect of ND in a eutectic mixture with PEG 4000 and a monotectic mixture with urea was potentiated by 3.2 and 2.7-fold respectively compared with the untreated drug. © 2014 Royal Pharmaceutical Society.

Superfluid--Solid Quantum Phase Transitions and Landau-Ginzburg-Wilson Paradigm

NASA Astrophysics Data System (ADS)

Kuklov, A. B.; Prokof'ev, N. V.

2005-03-01

We study superfluid (SF)--solid zero-temperature transitions in 2d lattice boson/spin models by Worm-Algorithm Monte Carlo simulations. The SF -- Valence Bond Solid (VBS) transition was recently argued to be generically of II order in violation of the Ginzburg-Landau- Wilson (GLW) paradigm [1]. We simulate the J-current model on lattices up to 64x64x64, and observe that SF- columnar VBS and SF-checkerboard solid transitions are typically weak I-order ones and in small systems they may be confused with the continuous or high-symmetry points [2]. Thus, in the simulated model, the SF-VBS transition proceeds in agreement with the GLW paradigm. We explain this by dominance of standard particle and hole excitations, as opposed to fractionalized (spinon) excitations [1]. We developed a technique based on tunneling events (instantons) in the insulating phase which reveals charges of the revelant long-wave modes. While in 1d systems spinons are clearly seen in tunneling events, in two spatial dimensions tunneling is solely controlled by particles and holes in our system. This work is supported by NSF grant ITR-405460001 and PSC-CUNY- 665560035. [1] T. Senthil, A. Vishwanath, L. Balents, S. Sachdev, and M.P.A. Fisher, Science 303, 1490 (2004); [2] A.B. Kuklov, N.V. Prokof'ev, B.V. Svistunov, condmat/0406061; PRL, to be published.

Multi-phase CFD modeling of solid sorbent carbon capture system

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

Ryan, E. M.; DeCroix, D.; Breault, R.

2013-07-01

Computational fluid dynamics (CFD) simulations are used to investigate a low temperature post-combustion carbon capture reactor. The CFD models are based on a small scale solid sorbent carbon capture reactor design from ADA-ES and Southern Company. The reactor is a fluidized bed design based on a silica-supported amine sorbent. CFD models using both Eulerian–Eulerian and Eulerian–Lagrangian multi-phase modeling methods are developed to investigate the hydrodynamics and adsorption of carbon dioxide in the reactor. Models developed in both FLUENT® and BARRACUDA are presented to explore the strengths and weaknesses of state of the art CFD codes for modeling multi-phase carbon capturemore » reactors. The results of the simulations show that the FLUENT® Eulerian–Lagrangian simulations (DDPM) are unstable for the given reactor design; while the BARRACUDA Eulerian–Lagrangian model is able to simulate the system given appropriate simplifying assumptions. FLUENT® Eulerian–Eulerian simulations also provide a stable solution for the carbon capture reactor given the appropriate simplifying assumptions.« less

Multi-Phase CFD Modeling of Solid Sorbent Carbon Capture System

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

Ryan, Emily M.; DeCroix, David; Breault, Ronald W.

2013-07-30

Computational fluid dynamics (CFD) simulations are used to investigate a low temperature post-combustion carbon capture reactor. The CFD models are based on a small scale solid sorbent carbon capture reactor design from ADA-ES and Southern Company. The reactor is a fluidized bed design based on a silica-supported amine sorbent. CFD models using both Eulerian-Eulerian and Eulerian-Lagrangian multi-phase modeling methods are developed to investigate the hydrodynamics and adsorption of carbon dioxide in the reactor. Models developed in both FLUENT® and BARRACUDA are presented to explore the strengths and weaknesses of state of the art CFD codes for modeling multi-phase carbon capturemore » reactors. The results of the simulations show that the FLUENT® Eulerian-Lagrangian simulations (DDPM) are unstable for the given reactor design; while the BARRACUDA Eulerian-Lagrangian model is able to simulate the system given appropriate simplifying assumptions. FLUENT® Eulerian-Eulerian simulations also provide a stable solution for the carbon capture reactor given the appropriate simplifying assumptions.« less

Calculation of Electronic Structure and Field Induced Magnetic Collapse in Ferroic Materials

NASA Astrophysics Data System (ADS)

Entel, Peter; Arróyave, Raymundo; Singh, Navdeep; Sokolovskiy, Vladimir V.; Buchelnikov, Vasiliy D.

We have performed ab inito electronic structure calculations and Monte Carlo simulations of FeRh, Mn3GaC and Heusler intermetallics alloys such as Ni-Co-Cr-Mn-(Ga, In, Sn) which are of interest for solid refrigeration and energy systems, an emerging technology involving such solid-solid systems. The calculations reveal that the important magnetic phase diagrams of these alloys which show the magnetic collapse and allow predictions of the related magnetocaloric effect (MCE) which they exhibit at finite temperatures, can be obtained by ab inito and Monte Carlo computations in qualitatively good agreement with experimental data. This is a one-step procedure from theory to alloy design of ferroic functional devices.

Theory of amorphous ices.

PubMed

Limmer, David T; Chandler, David

2014-07-01

We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens.

Characterization of van der Waals type bimodal,- lambda,- meta- and spinodal phase transitions in liquid mixtures, solid suspensions and thin films.

PubMed

Rosenholm, Jarl B

2018-03-01

The perfect gas law is used as a reference when selecting state variables (P, V, T, n) needed to characterize ideal gases (vapors), liquids and solids. Van der Waals equation of state is used as a reference for models characterizing interactions in liquids, solids and their mixtures. Van der Waals loop introduces meta- and unstable states between the observed gas (vapor)-liquid P-V transitions at low T. These intermediate states are shown to appear also between liquid-liquid, liquid-solid and solid-solid phase transitions. First-order phase transitions are characterized by a sharp discontinuity of first-order partial derivatives (P, S, V) of Helmholtz and Gibbs free energies. Second-order partial derivatives (K T , B, C V , C P , E) consist of a static contribution relating to second-order phase transitions and a relaxation contribution representing the degree of first-order phase transitions. Bimodal (first-order) and spinodal (second-order) phase boundaries are used to separate stable phases from metastable and unstable phases. The boundaries are identified and quantified by partial derivatives of molar Gibbs free energy or chemical potentials with respect to P, S, V and composition (mole fractions). Molecules confined to spread Langmuir monolayers or adsorbed Gibbs monolayers are characterized by equation of state and adsorption isotherms relating to a two-dimensional van der Waals equation of state. The basic work of two-dimensional wetting (cohesion, adsorption, spreading, immersion), have to be adjusted by a horizontal surface pressure in the presence of adsorbed vapor layers. If the adsorption is extended to liquid films a vertical surface pressure (Π) may be added to account for the lateral interaction, thus restoring PV = ΠAh dependence of thin films. Van der Waals attraction, Coulomb repulsion and structural hydration forces contribute to the vertical surface pressure. A van der Waals type coexistence of ordered (dispersed) and disordered (aggregated) phases is shown to exist when liquid vapor is confined in capillaries (condensation-liquefaction-evaporation and flux). This pheno-menon can be experimentally illustrated with suspended nano-sized particles (flocculation-coagulation-peptisation of colloidal sols) being confined in sample holders of varying size. The self-assembled aggregates represent critical self-similar equilibrium structures corres-ponding to rate determining complexes in kinetics. Overall, a self-consistent thermodynamic framework is established for the characterization of two- and three-dimensional phase separations in one-, two- and three-component systems. Copyright © 2018 Elsevier B.V. All rights reserved.

A Two-Phase Solid/Fluid Model for Dense Granular Flows Including Dilatancy Effects

NASA Astrophysics Data System (ADS)

Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Narbona-Reina, Gladys

2015-04-01

We propose a thin layer depth-averaged two-phase model to describe solid-fluid mixtures such as debris flows. It describes the velocity of the two phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure, that itself modifies the friction within the granular phase (Iverson et al., 2010). The model is derived from a 3D two-phase model proposed by Jackson (2000) based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work (Bouchut et al., 2014). In particular, Pitman and Le replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's equations. We close the mixture equations by a weak compressibility relation involving a critical density, or equivalently a critical pressure. Moreover, we relax one boundary condition, making it possible for the fluid to escape the granular media when compression of the granular mass occurs. Furthermore, we introduce second order terms in the equations making it possible to describe the evolution of the pore fluid pressure in response to the compression/dilatation of the granular mass without prescribing an extra ad-hoc equation for the pore pressure. We prove that the energy balance associated with this Jackson closure is dissipative, as well as its thin layer associated model. We present several numerical tests for the 1D case that are compared to the results of the model proposed by Pitman and Le. Bouchut, Fernandez-Nieto, Mangeney, Narbona-Reina, 2014, ESAIM: Mathematical Modelling and Numerical Analysis, in press. Iverson et al., 2010, J. Geophys. Res. 115: F03005. Jackson, 2000, Cambridge Monographs on Mechanics. Pitman and Le, Phil.Trans. R. Soc. A 363, 1573-1601, 2005.

A Two-Phase Solid/Fluid Model for Dense Granular Flows Including Dilatancy Effects

NASA Astrophysics Data System (ADS)

Mangeney, A.; Bouchut, F.; Fernández-Nieto, E. D.; Narbona-Reina, G.; Kone, E. H.

2014-12-01

We propose a thin layer depth-averaged two-phase model to describe solid-fluid mixtures such as debris flows. It describes the velocity of the two phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure, that itself modifies the friction within the granular phase (Iverson et al., 2010). The model is derived from a 3D two-phase model proposed by Jackson (2000) based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work (Bouchut et al., 2014). In particular, Pitman and Le replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's equations. We close the mixture equations by a weak compressibility relation involving a critical density, or equivalently a critical pressure. Moreover, we relax one boundary condition, making it possible for the fluid to escape the granular media when compression of the granular mass occurs. Furthermore, we introduce second order terms in the equations making it possible to describe the evolution of the pore fluid pressure in response to the compression/dilatation of the granular mass without prescribing an extra ad-hoc equation for the pore pressure. We prove that the energy balance associated with this Jackson closure is dissipative, as well as its thin layer associated model. We present several numerical tests for the 1D case that are compared to the results of the model proposed by Pitman and Le. Bouchut, Fernandez-Nieto, Mangeney, Narbona-Reina, 2014, ESAIM: Mathematical Modelling and Numerical Analysis, in press. Iverson, Logan, LaHusen, Berti, 2010, J. Geophys. Res. 115: F03005. Jackson, 2000, Cambridge Monographs on Mechanics. Pitman and Le, Phil.Trans. R. Soc. A 363, 1573-1601, 2005.

Microemulsion and Sol-Gel Synthesized ZrO₂-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural.

PubMed

Parejas, Almudena; Montes, Vicente; Hidalgo-Carrillo, Jesús; Sánchez-López, Elena; Marinas, Alberto; Urbano, Francisco J

2017-12-18

Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively). Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water) reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO₂ (especially Zr-SG) are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

Attosecond control of electrons emitted from a nanoscale metal tip.

PubMed

Krüger, Michael; Schenk, Markus; Hommelhoff, Peter

2011-07-06

Attosecond science is based on steering electrons with the electric field of well controlled femtosecond laser pulses. It has led to the generation of extreme-ultraviolet pulses with a duration of less than 100 attoseconds (ref. 3; 1 as = 10(-18) s), to the measurement of intramolecular dynamics (by diffraction of an electron taken from the molecule under scrutiny) and to ultrafast electron holography. All these effects have been observed with atoms or molecules in the gas phase. Electrons liberated from solids by few-cycle laser pulses are also predicted to show a strong light-phase sensitivity, but only very small effects have been observed. Here we report that the spectra of electrons undergoing photoemission from a nanometre-scale tungsten tip show a dependence on the carrier-envelope phase of the laser, with a current modulation of up to 100 per cent. Depending on the carrier-envelope phase, electrons are emitted either from a single sub-500-attosecond interval of the 6-femtosecond laser pulse, or from two such intervals; the latter case leads to spectral interference. We also show that coherent elastic re-scattering of liberated electrons takes place at the metal surface. Owing to field enhancement at the tip, a simple laser oscillator reaches the peak electric field strengths required for attosecond experiments at 100-megahertz repetition rates, rendering complex amplified laser systems dispensable. Practically, this work represents a simple, extremely sensitive carrier-envelope phase sensor, which could be shrunk in volume to about one cubic centimetre. Our results indicate that the attosecond techniques developed with (and for) atoms and molecules can also be used with solids. In particular, we foresee subfemtosecond, subnanometre probing of collective electron dynamics (such as plasmon polaritons) in solid-state systems ranging in scale from mesoscopic solids to clusters and to single protruding atoms. ©2011 Macmillan Publishers Limited. All rights reserved

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

Kirka, Michael M.; Nandwana, Peeyush; Lee, Yousub

Additive manufacturing (AM) of metals is rapidly emerging as an established manufacturing process for metal components. Unlike traditional metals fabrication processes, metals fabricated via AM undergo localized thermal cycles during fabrication. As a result, AM presents the opportunity to control the liquid-solid phase transformation, i.e. material texture. But, thermal cycling presents challenges from the standpoint of solid-solid phase transformations. We will discuss the opportunities and challenges in metals AM in the context of texture control and associated solid-solid phase transformations in Ti-6Al-4V and Inconel 718.

Optimization of multiplexed PCR on an integrated microfluidic forensic platform for rapid DNA analysis.

PubMed

Estes, Matthew D; Yang, Jianing; Duane, Brett; Smith, Stan; Brooks, Carla; Nordquist, Alan; Zenhausern, Frederic

2012-12-07

This study reports the design, prototyping, and assay development of multiplexed polymerase chain reaction (PCR) on a plastic microfluidic device. Amplification of 17 DNA loci is carried out directly on-chip as part of a system for continuous workflow processing from sample preparation (SP) to capillary electrophoresis (CE). For enhanced performance of on-chip PCR amplification, improved control systems have been developed making use of customized Peltier assemblies, valve actuators, software, and amplification chemistry protocols. Multiple enhancements to the microfluidic chip design have been enacted to improve the reliability of sample delivery through the various on-chip modules. This work has been enabled by the encapsulation of PCR reagents into a solid phase material through an optimized Solid Phase Encapsulating Assay Mix (SPEAM) bead-based hydrogel fabrication process. SPEAM bead technology is reliably coupled with precise microfluidic metering and dispensing for efficient amplification and subsequent DNA short tandem repeat (STR) fragment analysis. This provides a means of on-chip reagent storage suitable for microfluidic automation, with the long shelf-life necessary for point-of-care (POC) or field deployable applications. This paper reports the first high quality 17-plex forensic STR amplification from a reference sample in a microfluidic chip with preloaded solid phase reagents, that is designed for integration with up and downstream processing.

Comprehensive automation of the solid phase extraction gas chromatographic mass spectrometric analysis (SPE-GC/MS) of opioids, cocaine, and metabolites from serum and other matrices.

PubMed

Lerch, Oliver; Temme, Oliver; Daldrup, Thomas

2014-07-01

The analysis of opioids, cocaine, and metabolites from blood serum is a routine task in forensic laboratories. Commonly, the employed methods include many manual or partly automated steps like protein precipitation, dilution, solid phase extraction, evaporation, and derivatization preceding a gas chromatography (GC)/mass spectrometry (MS) or liquid chromatography (LC)/MS analysis. In this study, a comprehensively automated method was developed from a validated, partly automated routine method. This was possible by replicating method parameters on the automated system. Only marginal optimization of parameters was necessary. The automation relying on an x-y-z robot after manual protein precipitation includes the solid phase extraction, evaporation of the eluate, derivatization (silylation with N-methyl-N-trimethylsilyltrifluoroacetamide, MSTFA), and injection into a GC/MS. A quantitative analysis of almost 170 authentic serum samples and more than 50 authentic samples of other matrices like urine, different tissues, and heart blood on cocaine, benzoylecgonine, methadone, morphine, codeine, 6-monoacetylmorphine, dihydrocodeine, and 7-aminoflunitrazepam was conducted with both methods proving that the analytical results are equivalent even near the limits of quantification (low ng/ml range). To our best knowledge, this application is the first one reported in the literature employing this sample preparation system.

NMR signal analysis to characterize solid, aqueous, and lipid phases in baked cakes.

PubMed

Le Grand, F; Cambert, M; Mariette, F

2007-12-26

Proton mobility was studied in molecular fractions of some model systems and of cake using a 1H nuclear magnetic resonance (NMR) relaxation technique. For cake, five spin-spin relaxation times (T2) were obtained from transverse relaxation curves: T2 (1) approximately 20 micros, T2 (2) approximately 0.2 ms, T2 (3) approximately 3 ms, T2 (4) approximately 50 ms, and T2 (2) approximately 165 ms. The faster component was attributed to the solid phase, components 2 and 3 were associated with the aqueous phase, and the two slowest components were linked to the lipid phase. After cooking, the crust contained more fat but less water than the center part of the cake. The amount of gelatinized starch was lower in the crust, and water was more mobile due to less interaction with macromolecules. This preliminary study revealed different effects of storage on the center and crust.

Phase fields of nickel silicides obtained by mechanical alloying in the nanocrystalline state

NASA Astrophysics Data System (ADS)

Datta, M. K.; Pabi, S. K.; Murty, B. S.

2000-06-01

Solid state reactions induced by mechanical alloying (MA) of elemental blends of Ni and Si have been studied over the entire composition range of the Ni-Si system. A monotonous increase of the lattice parameter of the Ni rich solid solution, Ni(Si), is observed with refinement of crystallite size. Nanocrystalline phase/phase mixtures of Ni(Si), Ni(Si)+Ni31Si12, Ni31Si12+Ni2Si, Ni2Si+NiSi and NiSi+Si, have been obtained during MA, over the composition ranges of 0-10, 10-28, 28-33, 33-50, and >50 at. % Si, respectively. The results clearly suggest that only congruent melting phases, Ni31Si12, Ni2Si, and NiSi form, while the formation of noncongruent melting phases, Ni3Si, Ni3Si2, and NiSi2, is bypassed in the nanocrystalline state. The phase formation during MA has been discussed based on thermodynamic arguments. The predicted phase fields obtained from effective free energy calculations are quite consistent with those obtained during MA.

Forming a three-dimensional porous organic network via solid-state explosion of organic single crystals.

PubMed

Bae, Seo-Yoon; Kim, Dongwook; Shin, Dongbin; Mahmood, Javeed; Jeon, In-Yup; Jung, Sun-Min; Shin, Sun-Hee; Kim, Seok-Jin; Park, Noejung; Lah, Myoung Soo; Baek, Jong-Beom

2017-11-17

Solid-state reaction of organic molecules holds a considerable advantage over liquid-phase processes in the manufacturing industry. However, the research progress in exploring this benefit is largely staggering, which leaves few liquid-phase systems to work with. Here, we show a synthetic protocol for the formation of a three-dimensional porous organic network via solid-state explosion of organic single crystals. The explosive reaction is realized by the Bergman reaction (cycloaromatization) of three enediyne groups on 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene. The origin of the explosion is systematically studied using single-crystal X-ray diffraction and differential scanning calorimetry, along with high-speed camera and density functional theory calculations. The results suggest that the solid-state explosion is triggered by an abrupt change in lattice energy induced by release of primer molecules in the 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene crystal lattice.

A metastable liquid melted from a crystalline solid under decompression

DOE PAGES

Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; ...

2017-01-23

A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid–solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. Themore » decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure–temperature region similar to where the supercooled liquid Bi is observed. Finally, akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought.« less

A metastable liquid melted from a crystalline solid under decompression

PubMed Central

Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kono, Yoshio; Park, Changyong; Kenney-Benson, Curtis; Shen, Guoyin

2017-01-01

A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid–solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. The decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure–temperature region similar to where the supercooled liquid Bi is observed. Akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought. PMID:28112152

Key Role of Nitrate in Phase Transitions of Urban Particles: Implications of Important Reactive Surfaces for Secondary Aerosol Formation

NASA Astrophysics Data System (ADS)

Sun, Jiaxing; Liu, Lei; Xu, Liang; Wang, Yuanyuan; Wu, Zhijun; Hu, Min; Shi, Zongbo; Li, Yongjie; Zhang, Xiaoye; Chen, Jianmin; Li, Weijun

2018-01-01

Ammonium sulfate (AS) and ammonium nitrate (AN) are key components of urban fine particles. Both field and model studies showed that heterogeneous reactions of SO2, NO2, and NH3 on wet aerosols accelerated the haze formation in northern China. However, little is known on phase transitions of AS-AN containing haze particles. Here hygroscopic properties of laboratory-generated AS-AN particles and individual particles collected during haze events in an urban site were investigated using an individual particle hygroscopicity system. AS-AN particles showed a two-stage deliquescence at mutual deliquescence relative humidity (MDRH) and full deliquescence relative humidity (DRH) and three physical states: solid before MDRH, solid-aqueous between MDRH and DRH, and aqueous after DRH. During hydration, urban haze particles displayed a solid core and aqueous shell at RH = 60-80% and aqueous phase at RH > 80%. Most particles were in aqueous phase at RH > 50% during dehydration. Our results show that AS content in individual particles determines their DRH and AN content determines their MDRH. AN content increase can reduce MDRH, which indicates occurrence of aqueous shell at lower RH. The humidity-dependent phase transitions of nitrate-abundant urban particles are important to provide reactive surfaces of secondary aerosol formation in the polluted air.

Phase diagram of two-dimensional hard ellipses.

PubMed

Bautista-Carbajal, Gustavo; Odriozola, Gerardo

2014-05-28

We report the phase diagram of two-dimensional hard ellipses as obtained from replica exchange Monte Carlo simulations. The replica exchange is implemented by expanding the isobaric ensemble in pressure. The phase diagram shows four regions: isotropic, nematic, plastic, and solid (letting aside the hexatic phase at the isotropic-plastic two-step transition [E. P. Bernard and W. Krauth, Phys. Rev. Lett. 107, 155704 (2011)]). At low anisotropies, the isotropic fluid turns into a plastic phase which in turn yields a solid for increasing pressure (area fraction). Intermediate anisotropies lead to a single first order transition (isotropic-solid). Finally, large anisotropies yield an isotropic-nematic transition at low pressures and a high-pressure nematic-solid transition. We obtain continuous isotropic-nematic transitions. For the transitions involving quasi-long-range positional ordering, i.e., isotropic-plastic, isotropic-solid, and nematic-solid, we observe bimodal probability density functions. This supports first order transition scenarios.

Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy.

PubMed

Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon

2014-11-26

We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

Rapid determination of trace nitrophenolic organics in water by combining solid-phase extraction with surface-assisted laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Chen, Y C; Shiea, J; Sunner, J

2000-01-01

A rapid technique for the screening of trace compounds in water by combining solid-phase extraction (SPE) with activated carbon surface-assisted laser desorption/ionization (SALDI) time-of-flight mass spectrometry is demonstrated. Activated carbon is used both as the sorbent in SPE and as the solid in the SALDI matrix system. This eliminates the need for an SPE elution process. After the analytes have been adsorbed on the surfaces of the activated carbon during SPE extraction, the activated carbon is directly mixed with the SALDI liquid and mass spectrometric analysis is performed. Trace phenolic compounds in water were used to demonstrate the effectiveness of the method. The detection limit for these compounds is in the ppb to ppt range. Copyright 2000 John Wiley & Sons, Ltd.

Disordering Chain Motions in Fluoropolymers

NASA Astrophysics Data System (ADS)

Holt, David B.; Farmer, Barry L.

1998-03-01

Rotational and conformational disorder play important roles in the solid state phases of fluoropolymers such as polytetrafluoro- ethylene (PTFE). Modeling disordering processes and transitions which occur in fluoropolymers has been hampered due to a lack of force field parameters that adequately describe both the intra- and intermolecular characteristics (conformations and distances) of these polymers in the solid state. A force field has been developed which overcomes these inadequacies and has been utilized in molecular dynamics simulations on a system of PTFE oligomers to investigate two of the primary disordering processes that occur in the solid phases: rotations of chains about their helical axes and the formation and subsequent behavior of helix reversals. The simulation results confirm helix reversal activity at low temperatures and demonstrate correlations between chain segment rotations or librations and helix reversal motion. A mechanism for large scale chain segment rotations is proposed.

Complex Fluids at Interfaces and Interfaces of Complex Fluids

NASA Astrophysics Data System (ADS)

Nouri, Mariam

The present thesis deals with two independent projects and is consequently divided into two parts. The first part details a computational study of the fluid structure of ring-shaped molecules and their positional and orientational molecular organizations in different degrees of confinement, while the second part concerns an experimental study of phase behavior and interfacial phenomena in confined colloid-polymer systems. In the first part, ring-shaped molecules are studied using Monte Carlo simulation techniques in one, two and three dimensions. The model used to describe ring-shaped molecules is composed of hard-spheres linked together to form planar rigid rings. For rings of various sizes and for a wide range of densities, positional and orientational orderings are reported in forms of pair distribution functions of the ring centers and correlation functions of the ring normal orientations. Special emphasis is given to understand structural formation at interfaces, i.e., the structure and orderings of these molecules when they are confined to two dimensions. In a plane but the rings themselves are free to rotate around all axes, nematic ordering is observed at sufficiently high densities. In the second part, phase equilibria of confined aqueous colloid-polymer systems are studied experimentally using fluorescence microscopy. Aqueous mixtures of fluorescent polystyrene spheres and polyacrylamide are confined between a glass slide and a coverslip. The phase diagram is determined as a function of the colloidal and polymer concentrations. Liquid-liquid phase coexistence between a colloid-rich phase and a polymer-rich phase occurs at intermediate polymer concentrations, while liquid-solid phase coexistence between a polymer-rich liquid and a colloid-rich solid is observed at high polymer concentrations. Interfacial thickness and tension of the interface between these coexisting phases are measured using image analysis techniques. It is also observed that the colloid-rich solid and liquid domains coarsen mainly by Ostwald ripening.

Solid-liquid phase coexistence of alkali nitrates from molecular dynamics simulations.

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

Jayaraman, Saivenkataraman

2010-03-01

Alkali nitrate eutectic mixtures are finding application as industrial heat transfer fluids in concentrated solar power generation systems. An important property for such applications is the melting point, or phase coexistence temperature. We have computed melting points for lithium, sodium and potassium nitrate from molecular dynamics simulations using a recently developed method, which uses thermodynamic integration to compute the free energy difference between the solid and liquid phases. The computed melting point for NaNO3 was within 15K of its experimental value, while for LiNO3 and KNO3, the computed melting points were within 100K of the experimental values [4]. We aremore » currently extending the approach to calculate melting temperatures for binary mixtures of lithium and sodium nitrate.« less

Mass balance evaluation of polybrominated diphenyl ethers in landfill leachate and potential for transfer from e-waste.

PubMed

Danon-Schaffer, Monica N; Mahecha-Botero, Andrés; Grace, John R; Ikonomou, Michael

2013-09-01

Previous research on brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) has largely focussed on their concentrations in the environment and their adverse effects on human health. This paper explores their transfer from waste streams to water and soil. A comprehensive mass balance model is developed to track polybrominated diphenyl ethers (PBDEs), originating from e-waste and non-e-waste solids leaching from a landfill. Stepwise debromination is assumed to occur in three sub-systems (e-waste, aqueous leachate phase, and non-e-waste solids). Analysis of landfill samples and laboratory results from a solid-liquid contacting chamber are used to estimate model parameters to simulate an urban landfill system, for past and future scenarios. Sensitivity tests to key model parameters were conducted. Lower BDEs require more time to disappear than high-molecular weight PBDEs, since debromination takes place in a stepwise manner, according to the simplified reaction scheme. Interphase mass transfer causes the decay pattern to be similar in all three sub-systems. The aqueous phase is predicted to be the first sub-system to eliminate PBDEs if their input to the landfill were to be stopped. The non-e-waste solids would be next, followed by the e-waste sub-system. The model shows that mass transfer is not rate-limiting, but the evolution over time depends on the kinetic degradation parameters. Experimental scatter makes model testing difficult. Nevertheless, the model provides qualitative understanding of the influence of key variables. Copyright © 2013 Elsevier B.V. All rights reserved.

Performance of planar single cell lanthanum gallate based solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Maffei, N.; Kuriakose, A. K.

A novel synthesis of high purity, single phase strontium-magnesium doped lanthanum gallate through a nitrate route is described. The prepared powder is formed into planar monolithic elements by uniaxial pressing followed by isostatic pressing and sintering. XRD analysis of the sintered elements reveal no detectable secondary phases. The performance of the electrolyte in solid oxide fuel cells (SOFC) with three different anode/cathode combinations tested at 700°C with respect to the J- V and power density is reported. The data show that the characteristics of this SOFC are strongly dependent on the particular anode/cathode system chosen.

JANNAF 36th Combustion Subcommittee Meeting. Volume 1

NASA Technical Reports Server (NTRS)

Fry, Ronald S. (Editor); Gannaway, Mary T. (Editor)

1999-01-01

Volume 1, the first of three volumes is a compilation of 47 unclassified/unlimited-distribution technical papers presented at the Joint Army-Navy-NASA-Air Force (JANNAF) 36th Combustion Subcommittee held jointly with the 24th Airbreathing Propulsion Subcommittee and 18th Propulsion Systems Hazards Subcommittee. The meeting was held on 18-21 October 1999 at NASA Kennedy Space Center and The DoubleTree Oceanfront Hotel, Cocoa Beach, Florida. Solid phase propellant combustion topics covered in this volume include cookoff phenomena in the pre- and post-ignition phases, solid rocket motor and gun propellant combustion, aluminized composite propellant combustion, combustion modeling and combustion instability and instability measurement techniques.

Convection Models for Ice-Water System: Dynamical Investigation of Phase Transition

NASA Astrophysics Data System (ADS)

Allu Peddinti, D.; McNamara, A. K.

2012-12-01

Ever since planetary missions of Voyager and Galileo revealed a dynamically altered surface of the icy moon Europa, a possible subsurface ocean under an icy shell has been speculated and surface features have been interpreted from an interior dynamics perspective. The physics of convection in a two phase water-ice system is governed by a wide set of physical parameters that include melting viscosity of ice, the variation of viscosity due to pressure and temperature, temperature contrast across and tidal heating within the system, and the evolving thickness of each layer. Due to the extreme viscosity contrast between liquid water and solid ice, it is not feasible to model the entire system to study convection. However, using a low-viscosity proxy (higher viscosity than the liquid water but much lower than solid ice) for the liquid phase provides a convenient approximation of the system, and allows for a relatively realistic representation of convection within the ice layer while also providing a self-consistent ice layer thickness that is a function of the thermal state of the system. In order to apply this method appropriately, we carefully examine the upper bound of viscosity required for the low-viscosity proxy to adequately represent the liquid phase. We identify upper bounds on the viscosity of the proxy liquid such that convective dynamics of the ice are not affected by further reductions of viscosity. Furthermore, we investigate how the temperature contrast across the system and viscosity contrast between liquid and ice control ice layer thickness. We also investigate ice shell thickening as a function of cooling, particularly how viscosity affects the conduction-to-convection transition within the ice shell. Finally, we present initial results that investigate the effects that latent heat of fusion (due to the ice-water phase transition) has on ice convection.

Iron-titanium oxyhydroxides which transport water into the deep upper mantle and mantle transition zone

NASA Astrophysics Data System (ADS)

Matsukage, K. N.; Nishihara, Y.

2015-12-01

We experimentally discovered a new hydrous phase in the system FeOOH-TiO2 at pressures of 10-16 GPa and temperatures of 1000-1600°C which corresponds to conditions of the deep upper mantle and the Earth's mantle transition zone. Seven different compositions in the FeOOH-TiO2 system having molar ratios of x = Ti/(Fe + Ti) = 0, 0.125, 0.25, 0.375, 0.5, 0.75 that were prepared by mixing reagent grade a-FeOOH (goethite) and TiO2 (anatase) powders were used as starting materials. High-pressure and high-temperature experiments were carried out using Kawai-type multi-anvil apparatus (Orange-1000 at Ehime University and SPI-1000 at Tokyo Institute of Technology). In this system, we identified two stable iron-titanium oxyhydroxide phases whose estimated composition is expressed by (FeH)1 - xTixO2 . One is the Fe-rich solid solution (x < 0.23) with e-FeOOH type crystal structure (e-phase, orthorhombic, P21nm) that was described by the previous studies (e.g., Suzuki 2010), and the other is the more Ti-rich solid solution (x > 0.35) with a-PbO2 type structure (a-phase, orthorhombic, Pbcn). The a-phase is stable up to 1500ºC for a composition of x = 0.5 and at least to 1600ºC for x = 0.75. Our result means that this phase is stable at average mantle temperature in the Earth's mantle transition zone. The Iron-titanium-rich hydrous phases was possible to stable in basalt + H2O system (e.g., Hashimoto and Matsukage 2013). Therefore our findings suggest that water transport in the Earth's deep interior is probably much more efficient than had been previously thought.

Renormalization group study of the melting of a two-dimensional system of collapsing hard disks

NASA Astrophysics Data System (ADS)

Ryzhov, V. N.; Tareyeva, E. E.; Fomin, Yu. D.; Tsiok, E. N.; Chumakov, E. S.

2017-06-01

We consider the melting of a two-dimensional system of collapsing hard disks (a system with a hard-disk potential to which a repulsive step is added) for different values of the repulsive-step width. We calculate the system phase diagram by the method of the density functional in crystallization theory using equations of the Berezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young theory to determine the lines of stability with respect to the dissociation of dislocation pairs, which corresponds to the continuous transition from the solid to the hexatic phase. We show that the crystal phase can melt via a continuous transition at low densities (the transition to the hexatic phase) with a subsequent transition from the hexatic phase to the isotropic liquid and via a first-order transition. Using the solution of renormalization group equations with the presence of singular defects (dislocations) in the system taken into account, we consider the influence of the renormalization of the elastic moduli on the form of the phase diagram.

Characterization of solid dispersions of itraconazole and hydroxypropylmethylcellulose prepared by melt extrusion, Part II.

PubMed

Six, Karel; Berghmans, Hugo; Leuner, Christian; Dressman, Jennifer; Van Werde, Kristof; Mullens, Jules; Benoist, Luc; Thimon, Mireille; Meublat, Laurent; Verreck, Geert; Peeters, Jef; Brewster, Marcus; Van den Mooter, Guy

2003-07-01

This study was done to elucidate the physical and pharmaceutical properties of itraconazole-HPMC dispersions and the influence of water on the phase separation. Extrudates were prepared using a corotating twin-screw hot-stage extruder with fixed process parameters. Modulated-temperature differential scanning calorimetry (MTDSC) and DSC 111 were used to examine the mixing behavior of itraconazole and the carrier by evaluation of the glass transition region. High temperature diffuse reflectance infrared transform spectroscopy (HT-DRIFT) was performed to reveal interactions between itraconazole and HPMC. Dissolution was performed to investigate the pharmaceutical performance of the dispersions. Although the dissolution rate of itraconazole significantly increased, we found that the solid dispersions do not form a homogeneous system. A different picture was obtained depending on the way MTDSC analysis was performed, i.e., using open or closed sample pans. Water can evaporate in open pans, which allows itraconazole to interact with HPMC and leads to a partially mixed phase. Analysis in hermetically closed pans revealed a further phase separation as water remains on the sample and impedes the interaction between drug and polymer. Solid dispersions of itraconazole and HPMC do not form a homogeneous phase.

Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide

NASA Astrophysics Data System (ADS)

Song, Zhibo; Wang, Qixing; Li, Ming-Yang; Li, Lain-Jong; Zheng, Yu Jie; Wang, Zhuo; Lin, Tingting; Chi, Dongzhi; Ding, Zijing; Huang, Yu Li; Thye Shen Wee, Andrew

2018-04-01

Hybrid van der Waals heterostructures constructed by the integration of organic molecules and two-dimensional (2D) transition metal dichalcogenide (TMD) materials have useful tunable properties for flexible electronic devices. Due to the chemically inert and atomically smooth nature of the TMD surface, well-defined crystalline organic films form atomically sharp interfaces facilitating optimal device performance. Here, the surface phase transformation of the supramolecular packing structure of fluorinated fullerene (C60F48 ) on single-layer tungsten diselenide (WSe2) is revealed by low-temperature scanning tunneling microscopy, from thermally stable liquid to solid phases as the coverage increases. Statistical analysis of the intermolecular interaction potential reveals that the repulsive dipole-dipole interaction induced by interfacial charge transfer and substrate-mediated interactions play important roles in stabilizing the liquid C60F48 phases. Theoretical calculations further suggest that the dipole moment per C60F48 molecule varies with the surface molecule density, and the liquid-solid transformation could be understood from the perspective of the thermodynamic free energy for open systems. This study offers insights into the growth behavior at 2D organic/TMD hybrid heterointerfaces.

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

PubMed

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

2015-10-27

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

Optimization of single crystals of solid electrolytes with tysonite-type structure (LaF3) for conductivity at 293 K: 2. Nonstoichiometric phases R 1- y M y F3- y ( R = La-Lu, Y; M = Sr, Ba)

NASA Astrophysics Data System (ADS)

Sorokin, N. I.; Sobolev, B. P.; Krivandina, E. A.; Zhmurova, Z. I.

2015-01-01

Single crystals of fluorine-conducting solid electrolytes R 1 - y Sr y F3 - y and R 1 - y Ba y F3 - y ( R = La-Lu, Y) with a tysonite-type structure (LaF3) have been optimized for room-temperature conductivity σ293 K. The optimization is based on high-temperature measurements of σ( T) in two-component nonstoichiometric phases R 1 - y M y F3 - y ( M = Sr, Ba) as a function of the MF2 content. Optimization for thermal stability is based on studying the phase diagrams of MF2- RF3 systems ( M = Sr, Ba) and the behavior of nonstoichiometric crystals upon heating when measuring temperature dependences σ( T). Single crystals of many studied R 1 - y Sr y F3 - y and R 1 - y Ba y F3 - y phases have σ293 K values large enough to use these materials in solid-state electrochemical devices (chemical sensors, fluorine-ion batteries, accumulators, etc.) operating at room temperature.

Improving the dissolution rate of poorly water soluble drug by solid dispersion and solid solution: pros and cons.

PubMed

Chokshi, Rina J; Zia, Hossein; Sandhu, Harpreet K; Shah, Navnit H; Malick, Waseem A

2007-01-01

The solid dispersions with poloxamer 188 (P188) and solid solutions with polyvinylpyrrolidone K30 (PVPK30) were evaluated and compared in an effort to improve aqueous solubility and bioavailability of a model hydrophobic drug. All preparations were characterized by differential scanning calorimetry, powder X-ray diffraction, intrinsic dissolution rates, and contact angle measurements. Accelerated stability studies also were conducted to determine the effects of aging on the stability of various formulations. The selected solid dispersion and solid solution formulations were further evaluated in beagle dogs for in vivo testing. Solid dispersions were characterized to show that the drug retains its crystallinity and forms a two-phase system. Solid solutions were characterized to be an amorphous monophasic system with transition of crystalline drug to amorphous state. The evaluation of the intrinsic dissolution rates of various preparations indicated that the solid solutions have higher initial dissolution rates compared with solid dispersions. However, after storage at accelerated conditions, the dissolution rates of solid solutions were lower due to partial reversion to crystalline form. The drug in solid dispersion showed better bioavailability in comparison to solid solution. Therefore, considering physical stability and in vivo study results, the solid dispersion was the most suitable choice to improve dissolution rates and hence the bioavailability of the poorly water soluble drug.

Phase equilibria, crystal structure and oxygen content of intermediate phases in the Y-Ba-Co-O system

NASA Astrophysics Data System (ADS)

Urusova, A. S.; Cherepanov, V. A.; Aksenova, T. V.; Gavrilova, L. Ya.; Kiselev, E. A.

2013-06-01

The phase equilibria in the Y-Ba-Co-O system were systematically studied at 1373 K in air. The intermediate phases formed in the Y-Ba-Co-O system at 1373 K in air were: YBaCo2O5+δ, YBaCo4O7 and BaCo1-yYyO3-δ (0.09≤y≤0.42). It was shown that YBaCo2O5+δ possesses tetragonal structure with the 3ap×3ap×2ap superstructure (sp. gr. P4/mmm). High-temperature X-ray diffraction analysis of the YBaCo2O5+δ in the temperature range from 298 K up to 1073 K under Po2=0.21 аtm has not shown any phase transformations. The value of oxygen content for the YBaCo2O5+δ at room temperature was estimated as 5.40 and at 1323 K it was equal to 5.04. Thermal expansion of sample shows a linear characteristics and the average thermal expansion coefficient (TEC) is about 13.8×10-6, K-1 in the temperature range 298-1273 K. The homogeneity range and crystal structure of the BaCo1-yYyO3-δ (0.09≤y≤0.42) solid solutions were determined by X-ray diffraction of quenched samples. All BaCo1-yYyO3-δ solid solutions were found to have cubic structure (sp. gr. Pm3m). The unit cell parameters were refined using Rietveld full-profile analysis. Oxygen nonstoichiometry of BaCo1-yYyO3-δ solid solutions with 0.1≤y≤0.4 was measured by means of thermogravimetric technique within the temperature range 298-1373 K in air. Thermal expansion of BaCo1-yYyO3-δ (у=0.0; 0.1; 0.2; 0.3) samples was studied within the temperature range 298-1200 K in air. The projection of isothermal-isobaric phase diagram for the Y-Ba-Co-O system to the compositional triangle of metallic components was presented.

Wetting and spreading at the molecular scale

NASA Technical Reports Server (NTRS)

Koplik, Joel; Banavar, Jayanth R.

1994-01-01

We have studied the microscopic aspects of the spreading of liquid drops on a solid surface by molecular dynamics simulations of coexisting three-phase Lennard-Jones systems of liquid, vapor and solid. We consider both spherically symmetric atoms and chain-like molecules, and a range of interaction strengths. As the attraction between liquid and solid increases we observed a smooth transition in spreading regimes, from partial to complete to terraced wetting. In the terraced case, where distinct monomolecular layers spread with different velocities, the layers are ordered but not solid, with qualitative behavior resembling recent experimental findings, but with interesting differences in the spreading rate.

Two-dimensional solid-phase extraction strategy for the selective enrichment of aminoglycosides in milk.

PubMed

Shen, Aijin; Wei, Jie; Yan, Jingyu; Jin, Gaowa; Ding, Junjie; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2017-03-01

An orthogonal two-dimensional solid-phase extraction strategy was established for the selective enrichment of three aminoglycosides including spectinomycin, streptomycin, and dihydrostreptomycin in milk. A reversed-phase liquid chromatography material (C 18 ) and a weak cation-exchange material (TGA) were integrated in a single solid-phase extraction cartridge. The feasibility of two-dimensional clean-up procedure that experienced two-step adsorption, two-step rinsing, and two-step elution was systematically investigated. Based on the orthogonality of reversed-phase and weak cation-exchange procedures, the two-dimensional solid-phase extraction strategy could minimize the interference from the hydrophobic matrix existing in traditional reversed-phase solid-phase extraction. In addition, high ionic strength in the extracts could be effectively removed before the second dimension of weak cation-exchange solid-phase extraction. Combined with liquid chromatography and tandem mass spectrometry, the optimized procedure was validated according to the European Union Commission directive 2002/657/EC. A good performance was achieved in terms of linearity, recovery, precision, decision limit, and detection capability in milk. Finally, the optimized two-dimensional clean-up procedure incorporated with liquid chromatography and tandem mass spectrometry was successfully applied to the rapid monitoring of aminoglycoside residues in milk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Compression on the Molecular Arrangement of Itraconazole-Soluplus Solid Dispersions: Induction of Liquid Crystals or Exacerbation of Phase Separation?

PubMed

Singh, Abhishek; Bharati, Avanish; Frederiks, Pauline; Verkinderen, Olivier; Goderis, Bart; Cardinaels, Ruth; Moldenaers, Paula; Van Humbeeck, Jan; Van den Mooter, Guy

2016-06-06

Predensification and compression are unit operations imperative to the manufacture of tablets and capsules. Such stress-inducing steps can cause destabilization of solid dispersions which can alter their molecular arrangement and ultimately affect dissolution rate and bioavailability. In this study, itraconazole-Soluplus solid dispersions with 50% (w/w) drug loading prepared by hot-melt extrusion (HME) were investigated. Compression was performed at both pharmaceutically relevant and extreme compression pressures and dwell times. The starting materials, powder, and compressed solid dispersions were analyzed using modulated differential scanning calorimetry (MDSC), X-ray diffraction (XRD), small- and wide-angle X-ray scattering (SWAXS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and broadband dielectric spectroscopy (BDS). MDSC analysis revealed that compression promotes phase separation of solid dispersions as indicated by an increase in glass transition width, occurrence of a peak in the nonreversing heat flow signal, and an increase in the net heat of fusion indicating crystallinity in the systems. SWAXS analysis ruled out the presence of mesophases. BDS measurements elucidated an increase in the Soluplus-rich regions of the solid dispersion upon compression. FTIR indicated changes in the spatiotemporal architecture of the solid dispersions mediated via disruption in hydrogen bonding and ultimately altered dynamics. These changes can have significant consequences on the final stability and performance of the solid dispersions.

Multiphase mean curvature flows with high mobility contrasts: A phase-field approach, with applications to nanowires

NASA Astrophysics Data System (ADS)

Bretin, Elie; Danescu, Alexandre; Penuelas, José; Masnou, Simon

2018-07-01

The structure of many multiphase systems is governed by an energy that penalizes the area of interfaces between phases weighted by surface tension coefficients. However, interface evolution laws depend also on interface mobility coefficients. Having in mind some applications where highly contrasted or even degenerate mobilities are involved, for which classical phase field models are inapplicable, we propose a new effective phase field approach to approximate multiphase mean curvature flows with mobilities. The key aspect of our model is to incorporate the mobilities not in the phase field energy (which is conventionally the case) but in the metric which determines the gradient flow. We show the consistency of such an approach by a formal analysis of the sharp interface limit. We also propose an efficient numerical scheme which allows us to illustrate the advantages of the model on various examples, as the wetting of droplets on solid surfaces or the simulation of nanowires growth generated by the so-called vapor-liquid-solid method.

Gel phase in hydrated calcium dipicolinate

NASA Astrophysics Data System (ADS)

Rajak, Pankaj; Mishra, Ankit; Sheng, Chunyang; Tiwari, Subodh; Krishnamoorthy, Aravind; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

2017-11-01

The mineralization of dipicolinic acid (DPA) molecules in bacterial spore cores with Ca2+ ions to form Ca-DPA is critical to the wet-heat resistance of spores. This resistance to "wet-heat" also depends on the physical properties of water and DPA in the hydrated Ca-DPA-rich protoplasm. Using reactive molecular dynamics simulations, we have determined the phase diagram of hydrated Ca-DPA as a function of temperature and water concentration, which shows the existence of a gel phase along with distinct solid-gel and gel-liquid phase transitions. Simulations reveal monotonically decreasing solid-gel-liquid transition temperatures with increasing hydration, which explains the experimental trend of wet-heat resistance of bacterial spores. Our observation of different phases of water also reconciles previous conflicting experimental findings on the state of water in bacterial spores. Further comparison with an unmineralized hydrated DPA system allows us to quantify the importance of Ca mineralization in decreasing diffusivity and increasing the heat resistance of the spore.

RNA buffers the phase separation behavior of prion-like RNA binding proteins.

PubMed

Maharana, Shovamayee; Wang, Jie; Papadopoulos, Dimitrios K; Richter, Doris; Pozniakovsky, Andrey; Poser, Ina; Bickle, Marc; Rizk, Sandra; Guillén-Boixet, Jordina; Franzmann, Titus M; Jahnel, Marcus; Marrone, Lara; Chang, Young-Tae; Sterneckert, Jared; Tomancak, Pavel; Hyman, Anthony A; Alberti, Simon

2018-05-25

Prion-like RNA binding proteins (RBPs) such as TDP43 and FUS are largely soluble in the nucleus but form solid pathological aggregates when mislocalized to the cytoplasm. What keeps these proteins soluble in the nucleus and promotes aggregation in the cytoplasm is still unknown. We report here that RNA critically regulates the phase behavior of prion-like RBPs. Low RNA/protein ratios promote phase separation into liquid droplets, whereas high ratios prevent droplet formation in vitro. Reduction of nuclear RNA levels or genetic ablation of RNA binding causes excessive phase separation and the formation of cytotoxic solid-like assemblies in cells. We propose that the nucleus is a buffered system in which high RNA concentrations keep RBPs soluble. Changes in RNA levels or RNA binding abilities of RBPs cause aberrant phase transitions. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Gas-particle partitioning of atmospheric aerosols: interplay of physical state, non-ideal mixing and morphology.

PubMed

Shiraiwa, Manabu; Zuend, Andreas; Bertram, Allan K; Seinfeld, John H

2013-07-21

Atmospheric aerosols, comprising organic compounds and inorganic salts, play a key role in air quality and climate. Mounting evidence exists that these particles frequently exhibit phase separation into predominantly organic and aqueous electrolyte-rich phases. As well, the presence of amorphous semi-solid or glassy particle phases has been established. Using the canonical system of ammonium sulfate mixed with organics from the ozone oxidation of α-pinene, we illustrate theoretically the interplay of physical state, non-ideality, and particle morphology affecting aerosol mass concentration and the characteristic timescale of gas-particle mass transfer. Phase separation can significantly affect overall particle mass and chemical composition. Semi-solid or glassy phases can kinetically inhibit the partitioning of semivolatile components and hygroscopic growth, in contrast to the traditional assumption that organic compounds exist in quasi-instantaneous gas-particle equilibrium. These effects have significant implications for the interpretation of laboratory data and the development of improved atmospheric air quality and climate models.

Adsorption of the Three-phase Emulsion on Various Solid Surfaces.

PubMed

Enomoto, Yasutaka; Imai, Yoko; Tajima, Kazuo

2017-07-01

The present study investigates the adsorption of the three-phase emulsion on various solid/water interfaces. Vesicles can be used as emulsifiers in the three-phase emulsions and act as an independent phase unlike the surfactant used in conventional emulsions; therefore, it is expected that the three-phase emulsion formed by the adhesion of vesicles to the oil/water interface will adsorb on various solid/water interfaces. The cationic three-phase emulsion was prepared to encourage emulsion adsorption on negatively charged solid substrates in water. The emulsifier polyoxyethylene-(10) hydrogenated castor oil was rendered cationic by mixing with the surfactant cetyltrimethylammonium bromide and then used to prepare the cationic three-phase emulsion of hexadecane-in-water. Three solid substrates (silicon, glass, and copper) were dipped in the cationic emulsion and the emulsion was found to adsorb on the solid substrates while maintaining its structure. The amount of hexadecane adsorbed on the various surfaces was investigated by gas chromatography and found to increase with increasing hexadecane concentration in the emulsion and eventually plateaued just like molecular adsorption. The maximum surface coverage of the emulsion on the substrates was approximately 80%. However, even the equivalent nonionic three-phase emulsion was found to adsorb on the three solid surfaces. This was attributed to a novel mechanism of irreversible adhesion via the van der Waals attractive force.

Manual Solid-Phase Peptide Synthesis of Metallocene-Peptide Bioconjugates

ERIC Educational Resources Information Center

Kirin, Srecko I.; Noor, Fozia; Metzler-Nolte, Nils; Mier, Walter

2007-01-01

A simple and relatively inexpensive procedure for preparing a biologically active peptide using solid phase peptide synthesis (SPPS) is described. Fourth-year undergraduate students have gained firsthand experience from the solid-phase synthesis techniques and they have become familiar with modern analytical techniques based on the particular…

Phase Transition of H 2 in Subnanometer Pores Observed at 75 K

DOE PAGES

Olsen, Raina J.; Gillespie, Andrew K.; Contescu, Cristian I.; ...

2017-10-30

In this paper, we report a phase transition in H 2 adsorbed in a locally graphitic Saran carbon with subnanometer pores 0.5–0.65 nm in width, in which two layers of hydrogen can just barely squeeze, provided they pack tightly. The phase transition is observed at 75 K, temperatures far higher than other systems in which an adsorbent is known to increase phase transition temperatures: for instance, H 2 melts at 14 K in the bulk, but at 20 K on graphite because the solid H 2 is stabilized by the surface structure. Here we observe a transition at 75 Kmore » and 77–200 bar: from a low-temperature, low-density phase to a high-temperature, higher density phase. We model the low-density phase as a monolayer commensurate solid composed mostly of para-H 2 (the ground nuclear spin state, S = 0) and the high-density phase as an orientationally ordered bilayer commensurate solid composed mostly of ortho-H 2 (S = 1). We attribute the increase in density with temperature to the fact that the oblong ortho-H 2 can pack more densely. The transition is observed using two experiments. The high-density phase is associated with an increase in neutron backscatter by a factor of 7.0 ± 0.1. Normally, hydrogen produces no backscatter (scattering angle >90°). This backscatter appears along with a discontinuous increase in the excitation mass from 1.2 amu to 21.0 ± 2.3 amu, which we associate with collective nuclear spin excitations in the orientationally ordered phase. Film densities were measured using hydrogen adsorption. Finally, no phase transition was observed in H 2 adsorbed in control activated carbon materials.« less

Phase Transition of H 2 in Subnanometer Pores Observed at 75 K

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

Olsen, Raina J.; Gillespie, Andrew K.; Contescu, Cristian I.

In this paper, we report a phase transition in H 2 adsorbed in a locally graphitic Saran carbon with subnanometer pores 0.5–0.65 nm in width, in which two layers of hydrogen can just barely squeeze, provided they pack tightly. The phase transition is observed at 75 K, temperatures far higher than other systems in which an adsorbent is known to increase phase transition temperatures: for instance, H 2 melts at 14 K in the bulk, but at 20 K on graphite because the solid H 2 is stabilized by the surface structure. Here we observe a transition at 75 Kmore » and 77–200 bar: from a low-temperature, low-density phase to a high-temperature, higher density phase. We model the low-density phase as a monolayer commensurate solid composed mostly of para-H 2 (the ground nuclear spin state, S = 0) and the high-density phase as an orientationally ordered bilayer commensurate solid composed mostly of ortho-H 2 (S = 1). We attribute the increase in density with temperature to the fact that the oblong ortho-H 2 can pack more densely. The transition is observed using two experiments. The high-density phase is associated with an increase in neutron backscatter by a factor of 7.0 ± 0.1. Normally, hydrogen produces no backscatter (scattering angle >90°). This backscatter appears along with a discontinuous increase in the excitation mass from 1.2 amu to 21.0 ± 2.3 amu, which we associate with collective nuclear spin excitations in the orientationally ordered phase. Film densities were measured using hydrogen adsorption. Finally, no phase transition was observed in H 2 adsorbed in control activated carbon materials.« less

Effect of solid-meal caloric content on gastric emptying kinetics of solids and liquids.

PubMed

Urbain, J L; Siegel, J A; Mortelmans, L; van Cutsem, E; van den Maegdenbergh, V; de Roo, M

1989-08-01

In this study, we have evaluated the effect of the caloric content of a physiological test meal on the gastric emptying kinetics of solids and liquids. 22 healthy male volunteers were studied in two groups matched for age. After an overnight fast, each volunteer underwent the same test procedure; in the first group (G I), 10 volunteers received a meal consisting of bread, 111In-DTPA water and 1 scrambled egg labeled with 99mTc-labelled sulphur colloid; in the second group (G II) 12 volunteers were given the same meal but with 2 labeled eggs in order to increase the caloric content of the solid phase meal. Simultaneous anterior and posterior images were recorded using a dual-headed gamma camera. Solid and liquid geometric mean data were analyzed to determine the lag phase, the emptying rate and the half-emptying time for both solids and liquids. Solid and liquid gastric half-emptying times were significantly prolonged in G II compared to G I volunteers. For the solid phased, the delay was accounted for by a longer lag phase and a decrease in the equilibrium emptying rate. The emptying rate of the liquid phase was significantly decreased in G II compared to G I. Within each group, no statistically significant difference was observed between solid and liquid emptying rates. We conclude that the caloric content of the solid portion of a meal not only alters the emptying of the solid phase but also affects the emptying of the liquid component of the meal.

Headspace sorptive solid phase microextraction (HS-SPME) combined with a spectrophotometry system: A simple glass devise for extraction and simultaneous determination of cyanide and thiocyanate in environmental and biological samples.

PubMed

Al-Saidi, H M; Al-Harbi, Sami A; Aljuhani, E H; El-Shahawi, M S

2016-10-01

A simple, low cost and efficient headspace sorptive solid phase microextraction (HS-SPME) method for determination of cyanide has been developed. The system comprises of a glass tube with two valves and a moveable glass slide fixed at its centre. It includes an acceptor phase polyurethane foam treated mercury (II) dithizonate [Hg(HDz)2-PUF] complex fixed inside by a septum cap in a cylindrical configuration (5.0cm length and 1.0cm diameter). The extraction is based upon the contact of the acceptor phase to the headspace and subsequently measuring the absorbance of the recovered mercury (II) dithizonate from PUFs sorbent. Unlike other HSSE, extraction and back - extractions was carried out in a closed system, thereby improving the analytical performance by preventing the analyte loss. Under the optimized conditions, a linear calibration plot in the range of 1.0-50.0µmolL(-1) was achieved with limits of detection (LOD) and quantification (LOQ) of 0.34, 1.2µmolL(-1) CN(-), respectively. Simultaneous analysis of cyanide and thiocyanate in saliva was also performed with satisfactory recoveries. Copyright © 2016. Published by Elsevier B.V.

Experimental Liquidus Studies of the Pb-Fe-Si-O System in Equilibrium with Metallic Pb

NASA Astrophysics Data System (ADS)

Shevchenko, M.; Jak, E.

2018-02-01

Phase equilibria of the Pb-Fe-Si-O system have been investigated at 943 K to 1773 K (670 °C to 1500 °C) for oxide liquid in equilibrium with liquid Pb metal and solid oxide phases: (a) quartz, tridymite, or cristobalite; (b) (fayalite + tridymite) or (fayalite + spinel); (c) spinel (Fe3O4); (d) complex lead-iron silicates (melanotekite PbO·FeO1.5·SiO2, barysilite 8PbO·FeO·6SiO2, 5PbO·FeO1.5·SiO2, and 6PbO·FeO1.5·SiO2); (e) lead silicates (Pb2SiO4, Pb11Si3O17); (f) lead ferrites (magnetoplumbite Pb1+ x Fe12- x O19- x solid solution range); and (g) lead oxide (PbO, massicot). High-temperature equilibration on primary phase or iridium substrates, followed by quenching and direct measurement of Pb, Fe, and Si concentrations in the phases with the electron probe X-ray microanalysis, has been used to accurately characterize the system in equilibrium with Pb metal. All results are projected onto the PbO-"FeO"-SiO2 plane for presentation purposes. The present study is the first systematic characterization of liquidus over a wide range of compositions in this system in equilibrium with metallic Pb.

A facility for gas- and condensed-phase measurements behind shock waves

NASA Astrophysics Data System (ADS)

Petersen, Eric L.; Rickard, Matthew J. A.; Crofton, Mark W.; Abbey, Erin D.; Traum, Matthew J.; Kalitan, Danielle M.

2005-09-01

A shock-tube facility consisting of two, single-pulse shock tubes for the study of fundamental processes related to gas-phase chemical kinetics and the formation and reaction of solid and liquid aerosols at elevated temperatures is described. Recent upgrades and additions include a new high-vacuum system, a new gas-handling system, a new control system and electronics, an optimized velocity-detection scheme, a computer-based data acquisition system, several optical diagnostics, and new techniques and procedures for handling experiments involving gas/powder mixtures. Test times on the order of 3 ms are possible with reflected-shock pressures up to 100 atm and temperatures greater than 4000 K. Applications for the shock-tube facility include the study of ignition delay times of fuel/oxidizer mixtures, the measurement of chemical kinetic reaction rates, the study of fundamental particle formation from the gas phase, and solid-particle vaporization, among others. The diagnostic techniques include standard differential laser absorption, FM laser absorption spectroscopy, laser extinction for particle volume fraction and size, temporally and spectrally resolved emission from gas-phase species, and a scanning mobility particle sizer for particle size distributions. Details on the set-up and operation of the shock tube and diagnostics are given, the results of a detailed uncertainty analysis on the accuracy of the test temperature inferred from the incident-shock velocity are provided, and some recent results are presented.

Theory of amorphous ices

PubMed Central

Limmer, David T.; Chandler, David

2014-01-01

We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens. PMID:24858957

Electron drift in a large scale solid xenon

DOE PAGES

Yoo, J.; Jaskierny, W. F.

2015-08-21

A study of charge drift in a large scale optically transparent solid xenon is reported. A pulsed high power xenon light source is used to liberate electrons from a photocathode. The drift speeds of the electrons are measured using a 8.7 cm long electrode in both the liquid and solid phase of xenon. In the liquid phase (163 K), the drift speed is 0.193 ± 0.003 cm/μs while the drift speed in the solid phase (157 K) is 0.397 ± 0.006 cm/μs at 900 V/cm over 8.0 cm of uniform electric fields. Furthermore, it is demonstrated that a factor twomore » faster electron drift speed in solid phase xenon compared to that in liquid in a large scale solid xenon.« less

Invited papers presented to a workshop on thermodynamics and kinetics of dust formation in the space medium. [condensation, nucleation, and interstellar dust

NASA Technical Reports Server (NTRS)

Robertson, P. C.

1978-01-01

Abstracts of 25 papers relating to condensation processes in the early solar system are presented. Special emphasis is given to the transition of an initial vapor phase in the space medium, the characterization of condensation environments, and condensation processes in the space medium. The question of whether some fraction of the solar system solids (particularly exemplified by meteoritic solids) may be interstellar grains that gathered in the region of the proto-sun, rather than being products of local condensation is addressed.

Phase diagrams and crystal growth

NASA Astrophysics Data System (ADS)

Venkrbec, Jan

1980-04-01

Phase diagrams are briefly treated as generalized property-composition relationships, with respect to crystal technology optimization. The treatment is based on mutual interaction of three systems related to semiconductors: (a) the semiconducting material systems, (b0 the data bank, (c) the system of crystallization methods. A model is proposed enabling optimatization on the path from application requirements to the desired material. Further, several examples of the selection as to the composition of LED and laser diode material are given. Some of molten-solution-zone methods are being successfully introduced for this purpose. Common features of these methods, the application of phase diagrams, and their pecularities compared with other crystallization methods are illustrated by schematic diagrams and by examples. LPE methods, particularly the steady-state LPE methods such as Woodall's ISM and Nishizawa's TDM-CVP, and the CAM-S (Crystallization Method Providing Composition Autocontrol in Situ) have been chosen as examples. Another approach of exploiting phase diagrams for optimal material selection and for determination of growth condition before experimentation through a simple calculation is presented on InP-GaP solid solutions. Ternary phase diagrams are visualized in space through calculation and constructions based on the corresponding thermodynamic models and anaglyphs. These make it easy to observe and qualitatively analyze the crystallization of every composition. Phase diagrams can be also used as a powerful tool for the deduction of new crystallization methods. Eutectic crystallization is an example of such an approach where a modified molten-solution-zone method can give a sandwich structure with an abrupt concentration change. The concentration of a component can range from 0 to 100% in the different solid phases.

Grain Floatation During Equiaxed Solidification of an Al-Cu Alloy in a Side-Cooled Cavity: Part II—Numerical Studies

NASA Astrophysics Data System (ADS)

Kumar, Arvind; Walker, Mike J.; Sundarraj, Suresh; Dutta, Pradip

2011-08-01

In this article, a single-phase, one-domain macroscopic model is developed for studying binary alloy solidification with moving equiaxed solid phase, along with the associated transport phenomena. In this model, issues such as thermosolutal convection, motion of solid phase relative to liquid and viscosity variations of the solid-liquid mixture with solid fraction in the mobile zone are taken into account. Using the model, the associated transport phenomena during solidification of Al-Cu alloys in a rectangular cavity are predicted. The results for temperature variation, segregation patterns, and eutectic fraction distribution are compared with data from in-house experiments. The model predictions compare well with the experimental results. To highlight the influence of solid phase movement on convection and final macrosegregation, the results of the current model are also compared with those obtained from the conventional solidification model with stationary solid phase. By including the independent movement of the solid phase into the fluid transport model, better predictions of macrosegregation, microstructure, and even shrinkage locations were obtained. Mechanical property prediction models based on microstructure will benefit from the improved accuracy of this model.

Solid phase pegylation of hemoglobin.

PubMed

Suo, Xiaoyan; Zheng, Chunyang; Yu, Pengzhan; Lu, Xiuling; Ma, Guanghui; Su, Zhiguo

2009-01-01

A solid phase conjugation process was developed for attachment of polyethylene glycol to hemoglobin molecule. Bovine hemoglobin was loaded onto an ion exchange chromatography column and adsorbed by the solid medium. Succinimidyl carbonate mPEG was introduced in the mobile phase after the adsorption. Pegylation took place between the hemoglobin on the solid phase, and the pegylation reagent in the liquid phase. A further elution was carried out to separate the pegylated and the unpegylated protein. Analysis by HPSEC, SDS-PAGE, and MALLS demonstrated that the fractions eluted from the solid phase contained well-defined components. Pegylated hemoglobin with one PEG chain was obtained with the yield of 75%, in comparison to the yield of 30% in the liquid phase pegylation. The P(50) values of the mono-pegylated hemoglobin, prepared with SC-mPEG 5 kDa, 10 kDa and 20 kDa, were 19.97, 20.23 and 20.54 mmHg, which were much closer to the value of red blood cells than that of pegylated hemoglobin prepared with the conventional method.

Mechanism of Formation of Li 7 P 3 S 11 Solid Electrolytes through Liquid Phase Synthesis

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

Wang, Yuxing; Lu, Dongping; Bowden, Mark

Crystalline Li7P3S11 is a promising solid electrolyte for all solid state lithium/lithium ion batteries. A controllable liquid phase synthesis of Li7P3S11 is more desirable compared to conventional mechanochemical synthesis, but recent attempts suffer from reduced ionic conductivities. Here we elucidate the formation mechanism of crystalline Li7P3S11 synthesized in the liquid phase (acetonitrile, or ACN). We conclude that the crystalline Li7P3S11 forms through a two-step reaction: 1) formation of solid Li3PS4∙ACN and amorphous Li2S∙P2S5 phases in the liquid phase; 2) solid-state conversion of the two phases. The implication of this two-step reaction mechanism to the morphology control and the transport propertiesmore » of liquid phase synthesized Li7P3S11 is identified and discussed.« less

EPOS data and service provision to scientists and other stakeholders

NASA Astrophysics Data System (ADS)

Cocco, Massimo; EPOS Team

2017-04-01

EPOS brings together European nations and combines solid Earth science infrastructures and their associated data and services together with the scientific expertise into one integrated delivery system for solid Earth science. By improving and facilitating the integration, access, use, and re-use of solid Earth science data, data products, services and facilities EPOS is developing a holistic, sustainable, multidisciplinary research platform to provide coordinated access to harmonized and quality controlled data from diverse Earth science disciplines, together with tools for their use in analysis and modelling. EPOS has been designed with the vision of creating a single distributed pan-European infrastructure for solid Earth science to support a safe and sustainable society. In accordance with this scientific vision, the EPOS mission is to integrate the diverse and advanced European Research Infrastructures for solid Earth relying on new e-science opportunities to monitor and unravel the dynamic and complex Earth System. EPOS is presently in its implementation phase, which consists of the EPOS IP project and the legal establishment of EPOS-ERIC. The EPOS Implementation Phase builds on the achievements of the successful EPOS Preparatory Phase project. The EPOS implementation phase will last from 2015 to 2019. The key objectives of the project are: implementing Thematic Core Services (TCS), the domain-specific service hubs for coordinating and harmonizing national resources/plans with the European dimension of EPOS; building the Integrated Core Services (ICS) to provide a novel research platform to different stakeholders; designing the access to distributed computational resources (ICS-D); ensuring sustainability and governance of TCS and EPOS-ERIC. Here we present the activities planned for the implementation phase focusing on the TCS, the ICS and on their interoperability. We will present and discuss the data and service provision focusing on the data, data-products, software and services (DDSS) presently under implementation, which will be validated and tested during the next eigheen months. To accomplish its mission, EPOS is engaging different stakeholders, not limited to scientists, to allow the Earth sciences to open new horizons in our understanding of the planet Earth and in contributing to prepare society for geo-hazards. Understanding how the Earth works as a system is critically important to modern society. Society needs resources to support home life, industry and business and it needs security in the face of natural hazards. Volcanic eruptions, earthquakes, floods, landslides, tsunamis, weather, and global climate change are all Earth phenomena impacting on society. Solid Earth science by bringing together many diverse disciplines such as geology, seismology, geodesy, volcanology, geomagnetism as well as chemistry and physics as they all apply to the workings of Earth, is the place where to find answers on how to maintain the Earth a safe, prosperous, and habitable planet.

Solar Power Satellite Microwave Transmission and Reception

NASA Technical Reports Server (NTRS)

Dietz, R. H.

1980-01-01

Numerous analytical and experimental investigations related to SPS microwave power transmission and reception are reported. Aspects discussed include system performance, phase control, power amplifiers, radiating elements, rectenna, solid state configurations, and planned program activities.

Numerical modelling and experimental study of liquid evaporation during gel formation

NASA Astrophysics Data System (ADS)

Pokusaev, B. G.; Khramtsov, D. P.

2017-11-01

Gels are promising materials in biotechnology and medicine as a medium for storing cells for bioprinting applications. Gel is a two-phase system consisting of solid medium and liquid phase. Understanding of a gel structure evolution and gel aging during liquid evaporation is a crucial step in developing new additive bioprinting technologies. A numerical and experimental study of liquid evaporation was performed. In experimental study an evaporation process of an agarose gel layer located on Petri dish was observed and mass difference was detected using electronic scales. Numerical model was based on a smoothed particle hydrodynamics method. Gel in a model was represented as a solid-liquid system and liquid evaporation was modelled due to capillary forces and heat transfer. Comparison of experimental data and numerical results demonstrated that model can adequately represent evaporation process in agarose gel.

Design and development of molecularly imprinted polymers for the selective extraction of deltamethrin in olive oil: An integrated computational-assisted approach.

PubMed

Martins, Nuno; Carreiro, Elisabete P; Locati, Abel; Ramalho, João P Prates; Cabrita, Maria João; Burke, Anthony J; Garcia, Raquel

2015-08-28

This work firstly addresses the design and development of molecularly imprinted systems selective for deltamethrin aiming to provide a suitable sorbent for solid phase (SPE) extraction that will be further used for the implementation of an analytical methodology for the trace analysis of the target pesticide in spiked olive oil samples. To achieve this goal, a preliminary evaluation of the molecular recognition and selectivity of the molecularly imprinted polymers has been performed. In order to investigate the complexity of the mechanistic basis for template selective recognition in these polymeric matrices, the use of a quantum chemical approach has been attempted providing new insights about the mechanisms underlying template recognition, and in particular the crucial role of the crosslinker agent and the solvent used. Thus, DFT calculations corroborate the results obtained by experimental molecular recognition assays enabling one to select the most suitable imprinting system for MISPE extraction technique which encompasses acrylamide as functional monomer and ethylene glycol dimethacrylate as crosslinker. Furthermore, an analytical methodology comprising a sample preparation step based on solid phase extraction has been implemented using this "tailor made" imprinting system as sorbent, for the selective isolation/pre-concentration of deltamethrin from olive oil samples. Molecularly imprinted solid phase extraction (MISPE) methodology was successfully applied for the clean-up of spiked olive oil samples, with recovery rates up to 94%. Copyright © 2015 Elsevier B.V. All rights reserved.

Melt-Vapor Phase Diagram of the Te-S System

NASA Astrophysics Data System (ADS)

Volodin, V. N.; Trebukhov, S. A.; Kenzhaliyev, B. K.; Nitsenko, A. V.; Burabaeva, N. M.

2018-03-01

The values of partial pressure of saturated vapor of the constituents of the Te-S system are determined from boiling points. The boundaries of the melt-vapor phase transition at atmospheric pressure and in vacuum of 2000 and 100 Pa are calculated on the basis of partial pressures. A phase diagram that includes vapor-liquid equilibrium fields whose boundaries allow us to assess the behavior of elements upon distillation fractioning is plotted. It is established that the separation of elements is possible at the first evaporation-condensation cycle. Complications can be caused by crystallization of a sulfur solid solution in tellurium.

Engineered glass seals for solid-oxide fuel cells

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

Surdoval, Wayne; Lara-Curzio, Edgar; Stevenson, Jeffry

2017-02-07

A seal for a solid oxide fuel cell includes a glass matrix having glass percolation therethrough and having a glass transition temperature below 650.degree. C. A deformable second phase material is dispersed in the glass matrix. The second phase material can be a compliant material. The second phase material can be a crushable material. A solid oxide fuel cell, a precursor for forming a seal for a solid oxide fuel cell, and a method of making a seal for a solid oxide fuel cell are also disclosed.

Surface CHEMKIN (Version 4. 0): A Fortran package for analyzing heterogeneous chemical kinetics at a solid-surface---gas-phase interface

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

Coltrin, M.E.; Kee, R.J.; Rupley, F.M.

1991-07-01

Heterogeneous reaction at the interface between a solid surface and adjacent gas is central to many chemical processes. Our purpose for developing the software package SURFACE CHEMKIN was motivated by our need to understand the complex surface chemistry in chemical vapor deposition systems involving silicon, silicon nitride, and gallium arsenide. However, we have developed the approach and implemented the software in a general setting. Thus, we expect it will find use in such diverse applications as chemical vapor deposition, chemical etching, combustion of solids, and catalytic processes, and for a wide range of chemical systems. We believe that it providesmore » a powerful capability to help model, understand, and optimize important industrial and research chemical processes. The SURFACE CHEMKIN software is designed to work in conjunction with the CHEMKIN-2 software, which handles the chemical kinetics in the gas phase. It may also be used in conjunction with the Transport Property Package, which provides information about molecular diffusion. Thus, these three packages provide a foundation on which a user can build applications software to analyze gas-phase and heterogeneous chemistry in flowing systems. These packages should not be considered programs'' in the ordinary sense. That is, they are not designed to accept input, solve a particular problem, and report the answer. Instead, they are software tools intended to help a user work efficiently with large systems of chemical reactions and develop Fortran representations of systems of equations that define a particular problem. It is up the user to solve the problem and interpret the answer. 11 refs., 15 figs., 5 tabs.« less

Rapid determination of the volatile components in tobacco by ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction with gas chromatography-mass spectrometry.

PubMed

Yang, Yanqin; Chu, Guohai; Zhou, Guojun; Jiang, Jian; Yuan, Kailong; Pan, Yuanjiang; Song, Zhiyu; Li, Zuguang; Xia, Qian; Lu, Xinbo; Xiao, Weiqiang

2016-03-01

An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Moisture-Induced Amorphous Phase Separation of Amorphous Solid Dispersions: Molecular Mechanism, Microstructure, and Its Impact on Dissolution Performance.

PubMed

Chen, Huijun; Pui, Yipshu; Liu, Chengyu; Chen, Zhen; Su, Ching-Chiang; Hageman, Michael; Hussain, Munir; Haskell, Roy; Stefanski, Kevin; Foster, Kimberly; Gudmundsson, Olafur; Qian, Feng

2018-01-01

Amorphous phase separation (APS) is commonly observed in amorphous solid dispersions (ASD) when exposed to moisture. The objective of this study was to investigate: (1) the phase behavior of amorphous solid dispersions composed of a poorly water-soluble drug with extremely low crystallization propensity, BMS-817399, and PVP, following exposure to different relative humidity (RH), and (2) the impact of phase separation on the intrinsic dissolution rate of amorphous solid dispersion. Drug-polymer interaction was confirmed in ASDs at different drug loading using infrared (IR) spectroscopy and water vapor sorption analysis. It was found that the drug-polymer interaction could persist at low RH (≤75% RH) but was disrupted after exposure to high RH, with the advent of phase separation. Surface morphology and composition of 40/60 ASD at micro-/nano-scale before and after exposure to 95% RH were also compared. It was found that hydrophobic drug enriched on the surface of ASD after APS. However, for the 40/60 ASD system, the intrinsic dissolution rate of amorphous drug was hardly affected by the phase behavior of ASD, which may be partially attributed to the low crystallization tendency of amorphous BMS-817399 and enriched drug amount on the surface of ASD. Intrinsic dissolution rate of PVP decreased resulting from APS, leading to a lower concentration in the dissolution medium, but supersaturation maintenance was not anticipated to be altered after phase separation due to the limited ability of PVP to inhibit drug precipitation and prolong the supersaturation of drug in solution. This study indicated that for compounds with low crystallization propensity and high hydrophobicity, the risk of moisture-induced APS is high but such phase separation may not have profound impact on the drug dissolution performance of ASDs. Therefore, application of ASD technology on slow crystallizers could incur low risks not only in physical stability but also in dissolution performance. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Ultrasound shear wave imaging

NASA Astrophysics Data System (ADS)

Ye, Shigong; Wu, Junru

2000-05-01

Shear wave propagation properties including phase velocity and attenuation coefficient are indispensable information in materials characterization and nondestructive evaluation. A computer controlled scanning shear-wave ultrasonic imaging system has been developed. It consists of a pair of focusing broadband pvdf transducers of central frequency of 50 MHz immersed in distilled water. Shear waves in a solid specimen are generated by mode-conversion. When ultrasonic waves generated by one of the pvdf transducers impinge upon a solid specimen from water with angle of incidence of θ that is greater than θcr, the critical angle of the longitudinal wave in the solid, only shear waves can propagate in the solid and longitudinal waves become evanescent waves. The shear waves pass through the specimen and received by the other pvdf transducer. Meanwhile, the specimen was scanned by a stepped motor of a step of 10 μm. The system was used to generated shear waves amplitude and phase velocity images of bone specimen of 1280 μm and they are compared with their longitudinal wave counterparts. The results have shown shear wave images can provide additional shear modulus and shear viscous information that longitudinal waves can't provide. The lateral resolution of 60 μm was achieved using shear wave imaging technique applied in bone sample.

Liquid-phase and solid-phase microwave irradiations for reduction of graphite oxide

NASA Astrophysics Data System (ADS)

Zhao, Na; Wen, Chen-Yu; Zhang, David Wei; Wu, Dong-Ping; Zhang, Zhi-Bin; Zhang, Shi-Li

2014-12-01

In this paper, two microwave irradiation methods: (i) liquid-phase microwave irradiation (MWI) reduction of graphite oxide suspension dissolved in de-ionized water and N, N-dimethylformamide, respectively, and (ii) solid-phase MWI reduction of graphite oxide powder have been successfully carried out to reduce graphite oxide. The reduced graphene oxide products are thoroughly characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectral analysis, Raman spectroscopy, UV-Vis absorption spectral analysis, and four-point probe conductivity measurements. The results show that both methods can efficiently remove the oxygen-containing functional groups attached to the graphite layers, though the solid-phase MWI reduction method can obtain far more efficiently a higher quality-reduced graphene oxide with fewer defects. The I(D)/I(G) ratio of the solid-phase MWI sample is as low as 0.46, which is only half of that of the liquid-phase MWI samples. The electrical conductivity of the reduced graphene oxide by the solid method reaches 747.9 S/m, which is about 25 times higher than that made by the liquid-phase method.

Solid State Energy Conversion Energy Alliance (SECA)

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

Hennessy, Daniel; Sibisan, Rodica; Rasmussen, Mike

2011-09-12

The overall objective is to develop a Solid Oxide Fuel Cell (SOFC) stack that can be economically produced in high volumes and mass customized for different applications in transportation, stationary power generation, and military market sectors. In Phase I, work will be conducted on system design and integration, stack development, and development of reformers for natural gas and gasoline. Specifically, Delphi-Battelle will fabricate and test a 5 kW stationary power generation system consisting of a SOFC stack, a steam reformer for natural gas, and balance-of-plant (BOP) components, having an expected efficiency of ≥ 35 percent (AC/LHV). In Phase II andmore » Phase III, the emphasis will be to improve the SOFC stack, reduce start-up time, improve thermal cyclability, demonstrate operation on diesel fuel, and substantially reduce materials and manufacturing cost by integrating several functions into one component and thus reducing the number of components in the system. In Phase II, Delphi-Battelle will fabricate and demonstrate two SOFC systems: an improved stationary power generation system consisting of an improved SOFC stack with integrated reformation of natural gas, and the BOP components, with an expected efficiency of ≥ 40 percent (AC/LHV), and a mobile 5 kW system for heavy-duty trucks and military power applications consisting of an SOFC stack, reformer utilizing anode tailgate recycle for diesel fuel, and BOP components, with an expected efficiency of ≥ 30 percent (DC/LHV). Finally, in Phase III, Delphi-Battelle will fabricate and test a 5 kW Auxiliary Power Unit (APU) for mass-market automotive application consisting of an optimized SOFC stack, an optimized catalytic partial oxidation (CPO) reformer for gasoline, and BOP components, having an expected efficiency of ≥ 30 percent (DC/LHV) and a factory cost of ≤ $400/kW.« less

Phase shift method to estimate solids circulation rate in circulating fluidized beds

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

Ludlow, James Christopher; Panday, Rupen; Shadle, Lawrence J.

2013-01-01

While solids circulation rate is a critical design and control parameter in circulating fluidized bed (CFB) reactor systems, there are no available techniques to measure it directly at conditions of industrial interest. Cold flow tests have been conducted at NETL in an industrial scale CFB unit where the solids flow has been the topic of research in order to develop an independent method which could be applied to CFBs operating under the erosive and corrosive high temperatures and pressures of a coal fired boiler or gasifier. The dynamic responses of the CFB loop to modest modulated aeration flows in themore » return leg or standpipe were imposed to establish a periodic response in the unit without causing upset in the process performance. The resulting periodic behavior could then be analyzed with a dynamic model and the average solids circulation rate could be established. This method was applied to the CFB unit operated under a wide range of operating conditions including fast fluidization, core annular flow, dilute and dense transport, and dense suspension upflow. In addition, the system was operated in both low and high total solids inventories to explore the influence of inventory limiting cases on the estimated results. The technique was able to estimate the solids circulation rate for all transport circulating fluidized beds when operating above upper transport velocity, U{sub tr2}. For CFB operating in the fast fluidized bed regime (i.e., U{sub g}< U{sub tr2}), the phase shift technique was not successful. The riser pressure drop becomes independent of the solids circulation rate and the mass flow rate out of the riser does not show modulated behavior even when the riser pressure drop does.« less

The investigation of solid slag obtained by neutralization of sewage sludge.

PubMed

Kavaliauskas, Zydrunas; Valincius, Vitas; Stravinskas, Giedrius; Milieska, Mindaugas; Striugas, Nerijus

2015-11-01

The purpose of this research is to investigate the feasibility of utilizing the slag collected after gasification of organic fuel combined with sewage sludge. The residue left after gasification process is likely usable as raw material for production of supercondensers. The sewage sludge neutralization system consists of a dosing system (fuel tank), gasifier, plasma reactor, electrostatic filter, and heat exchangers. For the gasification process, dried solid sewage is supplied in proportion of 70% to biomass 30% by weight. The slag is collected in a specially designed chamber beneath the gasifier. A scanning electron microscope (SEM) was used to evaluate surface morphology of the samples. Elemental analysis of the sewage sludge slag was performed using the energy-dispersive spectroscopy (EDS) method, which showed different solid-state elements contained in the porous structure of the solid phase: carbon 29%, aluminum 26%, potassium 20%, chlorine 1%, and others. The specific surface area of the sewage sludge slag is 6.15 m(2)/g as the BET analysis shows. In order to use the slag as a secondary raw material, detailed analysis of the structure and properties is necessary for a decision on whether the slag left after gasification of sewage sludge is suitable for any further usages. Initial results indicate that the slag may be used for production of electrodes for supercapacitors. Every year thousands of tons of sewage sludge are formed in Lithuania. Sewage sludge consists of organic and inorganic compounds. Partial combustion, plasma decomposition, and other methods are used to neutralize the sewage sludge. The incineration of sewage sludge results in generation of solid-phase slag. In this paper the material structure and composition of a solid slag (formed during neutralization of sewage sludge) is considered. Also, the impact the ambient temperature on structure and composition of solid slag is analyzed.

Estimating production and consumption of solid reactive Fe phases in marine sediments from concentration profiles

EPA Science Inventory

1D diffusion models may be used to estimate rates of production and consumption of dissolved metabolites in marine sediments, but are applied less often to the solid phase. Here we used a numerical inverse method to estimate solid phase Fe(III) and Fe(II) consumption and product...

Molecular-level understanding of protein adsorption at the interface between water and a strongly interacting uncharged solid surface.

PubMed

Penna, Matthew J; Mijajlovic, Milan; Biggs, Mark J

2014-04-09

Although protein adsorption on solids is of immense relevance, experimental limitations mean there is still a remarkable lack of understanding of the adsorption mechanism, particularly at a molecular level. By subjecting 240+ molecular dynamics simulations of two peptide/water/solid surface systems to statistical analysis, a generalized molecular level mechanism for peptide adsorption has been identified for uncharged surfaces that interact strongly with the solution phase. This mechanism is composed of three phases: (1) biased diffusion of the peptide from the bulk phase toward the surface; (2) anchoring of the peptide to the water/solid interface via interaction of a hydrophilic group with the water adjacent to the surface or a strongly interacting hydrophobic group with the surface; and (3) lockdown of the peptide on the surface via a slow, stepwise and largely sequential adsorption of its residues, which we term 'statistical zippering'. The adsorption mechanism is dictated by the existence of water layers adjacent to the solid and orientational ordering therein. By extending the solid into the solution by ~8 Å and endowing it with a charged character, the water layers ensure the peptide feels the effect of the solid at a range well beyond the dispersion force that arises from it, thus inducing biased diffusion from afar. The charging of the interface also facilitates anchoring of the peptide near the surface via one of its hydrophilic groups, allowing it time it would otherwise not have to rearrange and lockdown. Finally, the slowness of the lockdown process is dictated by the need for the peptide groups to replace adjacent tightly bound interfacial water.

New insights into the thermal behaviour of organic ionic plastic crystals: magnetic resonance imaging of polycrystalline morphology alterations induced by solid-solid phase transitions.

PubMed

Romanenko, Konstantin; Pringle, Jennifer M; O'Dell, Luke A; Forsyth, Maria

2015-07-15

Organic ionic plastic crystals (OIPCs) show strong potential as solid-state electrolytes for lithium battery applications, demonstrating promising electrochemical performance and eliminating the need for a volatile and flammable liquid electrolyte. The ionic conductivity (σ) in these systems has recently been shown to depend strongly on polycrystalline morphology, which is largely determined by the sample's thermal history. [K. Romanenko et al., J. Am. Chem. Soc., 2014, 136, 15638]. Tailoring this morphology could lead to conductivities sufficiently high for battery applications, so a more complete understanding of how phenomena such as solid-solid phase transitions can affect the sample morphology is of significant interest. Anisotropic relaxation of nuclear spin magnetisation provides a new MRI based approach for studies of polycrystalline materials at both a macroscopic and molecular level. In this contribution, morphology alterations induced by solid-solid phase transitions in triisobutyl(methyl)phosphonium bis(fluorosulfonyl)imide (P1444FSI) and diethyl(methyl)(isobutyl)phosphonium hexafluorophosphate (P1224PF6) are examined using magnetic resonance imaging (MRI), alongside nuclear magnetic resonance (NMR) spectroscopy, diffusion measurements and conductivity data. These observations are linked to molecular dynamics and structural behaviour crucial for the conductive properties of OIPCs. A distinct correlation is established between the conductivity at a given temperature, σ(T), and the intensity of the narrow NMR signal that is attributed to a mobile fraction, fm(T), of ions in the OIPC. To explain these findings we propose an analogy with the well-studied relationship between permeability (k) and void fraction (θ) in porous media, with k(θ) commonly quantified by a power-law dependence that can also be employed to describe σ(fm).

Path-integral simulation of solids.

PubMed

Herrero, C P; Ramírez, R

2014-06-11

The path-integral formulation of the statistical mechanics of quantum many-body systems is described, with the purpose of introducing practical techniques for the simulation of solids. Monte Carlo and molecular dynamics methods for distinguishable quantum particles are presented, with particular attention to the isothermal-isobaric ensemble. Applications of these computational techniques to different types of solids are reviewed, including noble-gas solids (helium and heavier elements), group-IV materials (diamond and elemental semiconductors), and molecular solids (with emphasis on hydrogen and ice). Structural, vibrational, and thermodynamic properties of these materials are discussed. Applications also include point defects in solids (structure and diffusion), as well as nuclear quantum effects in solid surfaces and adsorbates. Different phenomena are discussed, as solid-to-solid and orientational phase transitions, rates of quantum processes, classical-to-quantum crossover, and various finite-temperature anharmonic effects (thermal expansion, isotopic effects, electron-phonon interactions). Nuclear quantum effects are most remarkable in the presence of light atoms, so that especial emphasis is laid on solids containing hydrogen as a constituent element or as an impurity.

Performance of temperature-phased anaerobic digestion (TPAD) system treating dairy cattle wastes.

PubMed

Sung, Shihwu; Santha, Harikishan

2003-04-01

The performance of temperature-phased anaerobic digestion (TPAD) system in the stabilization of dairy cattle wastes at high solids concentrations has never been evaluated, though the process has been established as a feasible alternative to conventional mesophilic processes for the treatment of municipal wastewater sludges. In this study, the TPAD system operating at a retention time of 14 days was subjected to varying total solids (TS) concentrations (3.46-14.54%) of dairy cattle wastes. At TS concentrations lower than 12.20%, corresponding to system volatile solids (VS) loadings in the range of 1.87-5.82 g VS/L/day, the system achieved an average VS removal of 40.2%. The maximum VS destruction of 42.6% was achieved at a TS concentration of 10.35%. Methane recovery from the wastes was consistently within 0.21-0.22 L/g VS fed. There was a drop in the system performance with respect to VS removal and methane recovery at TS concentrations higher than 10.35%. volatile fatty acid/alkalinity ratios less than 0.35 in the thermophilic reactor and 0.10 in the mesophilic reactor were found favorable for stable operation of the system. For the entire range of TS concentrations, the indicator organism counts in the biosolids were within the limits specified by USEPA in 40 CFR Part 503 regulations for Class A designation. After digestion, nearly 80-85% of total phosphorus was associated with the biosolids. Copyright 2002 Elsevier Science Ltd.

Transformation impacts of dissolved and solid phase Fe(II) on trichloroethylene (TCE) reduction in an iron-reducing bacteria (IRB) mixed column system: a mathematical model.

PubMed

Bae, Yeunook; Kim, Dooil; Cho, Hyun-Hee; Singhal, Naresh; Park, Jae-Woo

2012-12-01

In this research, we conducted trichloroethylene (TCE) reduction in a column filled with iron and iron-reducing bacteria (IRB) and developed a mathematical model to investigate the critical reactions between active species in iron/IRB/contaminant systems. The formation of ferrous iron (Fe(II)) in this system with IRB and zero-valent iron (ZVI, Fe(0)) coated with a ferric iron (Fe(III)) crust significantly affected TCE reduction and IRB respiration in various ways. This study presents a new framework for transformation property and reducing ability of both dissolved (Fe(II)(dissolved)) and solid form ferrous iron (Fe(II)(solid)). Results showed that TCE reduction was strongly depressed by Fe(II)(solid) rather than by other inhibitors (e.g., Fe(III) and lactate), suggesting that Fe(II)(solid) might reduce IRB activation due to attachment to IRB cells. Newly exposed Fe(0) from the released Fe(II)(dissolved) was a strong contributor to TCE reduction compared to Fe(II)(solid). In addition, our research confirmed that less Fe(II)(solid) production strongly supported long-term TCE reduction because it may create an easier TCE approach to Fe(0) or increase IRB growth. Our findings will aid the understanding of the contributions of iron media (e.g., Fe(II)(solid), Fe(II)(dissolved), Fe(III), and Fe(0)) to IRB for decontamination in natural groundwater systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Phase Behavior of γ-Oryzanol and β-Sitosterol in Edible Oil.

PubMed

Sawalha, Hassan; Venema, Paul; Bot, Arjen; Flöter, Eckhard; Adel, Ruud den; van der Linden, Erik

The phase behavior of binary mixtures of γ-oryzanol and β-sitosterol and ternary mixtures of γ-oryzanol and β-sitosterol in sunflower oil was studied. Binary mixtures of γ-oryzanol and β-sitosterol show double-eutectic behavior. Complex phase behavior with two intermediate mixed solid phases was derived from differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) data, in which a compound that consists of γ-oryzanol and β-sitosterol molecules at a specific ratio can be formed. SAXS shows that the organization of γ-oryzanol and β-sitosterol in the mixed phases is different from the structure of tubules in ternary systems. Ternary mixtures including sunflower oil do not show a sudden structural transition from the compound to a tubule, but a gradual transition occurs as γ-oryzanol and β-sitosterol are diluted in edible oil. The same behavior is observed when melting binary mixtures of γ-oryzanol and β-sitosterol at higher temperatures. This indicates the feasibility of having an organogelling agent in dynamic exchange between solid and liquid phase, which is an essential feature of triglyceride networks.

Phase equilibrium in argon films stabilized by homogeneous surfaces and thermodynamics of two-stage melting transition.

PubMed

Ustinov, E A

2014-02-21

Freezing of gases adsorbed on open surfaces (e.g., graphite) and in narrow pores is a widespread phenomenon which is a subject of a large number of publications. Modeling of the gas/liquid-solid transition is usually accomplished with a molecular simulation technique. However, quantitative analysis of the gas/liquid-solid coexistence and thermodynamic properties of the solid layer still encounters serious difficulties. This is mainly due to the effect of simulation box size on the lattice constant. Since the lattice constant is a function of loading and temperature, once the ordering transition has occurred, the simulation box size must be corrected in the course of simulation according to the Gibbs-Duhem equation. A significant problem is also associated with accurate prediction of the two-dimensional liquid-solid coexistence because of a small difference in densities of coexisting phases. The aim of this study is thermodynamic analysis of the two-dimensional phase coexistence in systems involving crystal-like free of defects layers in narrow slit pores. A special attention was paid to the determination of triple point temperatures. It is shown that intrinsic properties of argon monolayer adsorbed on the graphite surface are similar to those of isolated monolayer accommodated in the slit pore having width of two argon collision diameters. Analysis of the latter system is shown to be clearer and less time-consuming than the former one, which has allowed for explanation of the experimentally observed two-stage melting transition of argon monolayer on graphite without invoking the periodic surface potential modulation and orientational transition.

Phase equilibrium in argon films stabilized by homogeneous surfaces and thermodynamics of two-stage melting transition

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

Ustinov, E. A., E-mail: eustinov@mail.wplus.net

Freezing of gases adsorbed on open surfaces (e.g., graphite) and in narrow pores is a widespread phenomenon which is a subject of a large number of publications. Modeling of the gas/liquid–solid transition is usually accomplished with a molecular simulation technique. However, quantitative analysis of the gas/liquid–solid coexistence and thermodynamic properties of the solid layer still encounters serious difficulties. This is mainly due to the effect of simulation box size on the lattice constant. Since the lattice constant is a function of loading and temperature, once the ordering transition has occurred, the simulation box size must be corrected in the coursemore » of simulation according to the Gibbs–Duhem equation. A significant problem is also associated with accurate prediction of the two-dimensional liquid–solid coexistence because of a small difference in densities of coexisting phases. The aim of this study is thermodynamic analysis of the two-dimensional phase coexistence in systems involving crystal-like free of defects layers in narrow slit pores. A special attention was paid to the determination of triple point temperatures. It is shown that intrinsic properties of argon monolayer adsorbed on the graphite surface are similar to those of isolated monolayer accommodated in the slit pore having width of two argon collision diameters. Analysis of the latter system is shown to be clearer and less time-consuming than the former one, which has allowed for explanation of the experimentally observed two-stage melting transition of argon monolayer on graphite without invoking the periodic surface potential modulation and orientational transition.« less

Processing of solid solution, mixed uranium/refractory metal carbides for advanced space nuclear power and propulsion systems

NASA Astrophysics Data System (ADS)

Knight, Travis Warren

Nuclear thermal propulsion (NTP) and space nuclear power are two enabling technologies for the manned exploration of space and the development of research outposts in space and on other planets such as Mars. Advanced carbide nuclear fuels have been proposed for application in space nuclear power and propulsion systems. This study examined the processing technologies and optimal parameters necessary to fabricate samples of single phase, solid solution, mixed uranium/refractory metal carbides. In particular, the pseudo-ternary carbide, UC-ZrC-NbC, system was examined with uranium metal mole fractions of 5% and 10% and corresponding uranium densities of 0.8 to 1.8 gU/cc. Efforts were directed to those methods that could produce simple geometry fuel elements or wafers such as those used to fabricate a Square Lattice Honeycomb (SLHC) fuel element and reactor core. Methods of cold uniaxial pressing, sintering by induction heating, and hot pressing by self-resistance heating were investigated. Solid solution, high density (low porosity) samples greater than 95% TD were processed by cold pressing at 150 MPa and sintering above 2600 K for times longer than 90 min. Some impurity oxide phases were noted in some samples attributed to residual gases in the furnace during processing. Also, some samples noted secondary phases of carbon and UC2 due to some hyperstoichiometric powder mixtures having carbon-to-metal ratios greater than one. In all, 33 mixed carbide samples were processed and analyzed with half bearing uranium as ternary carbides of UC-ZrC-NbC. Scanning electron microscopy, x-ray diffraction, and density measurements were used to characterize samples. Samples were processed from powders of the refractory mono-carbides and UC/UC 2 or from powders of uranium hydride (UH3), graphite, and refractory metal carbides to produce hypostoichiometric mixed carbides. Samples processed from the constituent carbide powders and sintered at temperatures above the melting point of UC showed signs of liquid phase sintering and were shown to be largely solid solutions. Pre-compaction of mixed carbide powders prior to sintering was shown to be necessary to achieve high densities. Hypostoichiometric, samples processed at 2500 K exhibited only the initial stage of sintering and solid solution formation. Based on these findings, a suggested processing methodology is proposed for producing high density, solid solution, mixed carbide fuels. Pseudo-binary, refractory carbide samples hot pressed at 3100 K and 6 MPa showed comparable densities (approximately 85% of the theoretical value) to samples processed by cold pressing and sintering at temperatures of 2800 K.

Shock Compression Response of Calcium Fluoride (CaF2)

NASA Astrophysics Data System (ADS)

Root, Seth

2017-06-01

The fluorite crystal structure is a textbook lattice that is observed for many systems, such as CaF2, Mg2 Si, and CeO2. Specifically, CaF2 is a useful material for studying the fluorite system because it is readily available as a single crystal. Under static compression, CaF2 is known to have at least three solid phases: fluorite, cotunnite, and a Ni2 In phase. Along the Hugoniot CaF2 undergoes a fluorite to cotunnite phase transition, however, at higher shock pressures it is unknown whether CaF2 undergoes another solid phase transition or melts directly from the cotunnite phase. In this work, we conducted planar shock compression experiments on CaF2 using Sandia's Z-machine and a two-stage light gun up to 900 GPa. In addition, we use density functional theory (DFT) based quantum molecular dynamics (QMD) simulations to provide insight into the CaF2 state along the Hugoniot. In collaboration with: Michael Desjarlais, Ray Lemke, Patricia Kalita, Scott Alexander, Sandia National Laboratories. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL850.

Modulated structure and molecular dissociation of solid chlorine at high pressures

NASA Astrophysics Data System (ADS)

Li, Peifang; Gao, Guoying; Ma, Yanming

2012-08-01

Among diatomic molecular halogen solids, high pressure structures of solid chlorine (Cl2) remain elusive and least studied. We here report first-principles structural search on solid Cl2 at high pressures through our developed particle-swarm optimization algorithm. We successfully reproduced the known molecular Cmca phase (phase I) at low pressure and found that it remains stable up to a high pressure 142 GPa. At 150 GPa, our structural searches identified several energetically competitive, structurally similar, and modulated structures. Analysis of the structural results and their similarity with those in solid Br2 and I2, it was suggested that solid Cl2 adopts an incommensurate modulated structure with a modulation wave close to 2/7 in a narrow pressure range 142-157 GPa. Eventually, our simulations at >157 GPa were able to predict the molecular dissociation of solid Cl2 into monatomic phases having body centered orthorhombic (bco) and face-centered cubic (fcc) structures, respectively. One unique monatomic structural feature of solid Cl2 is the absence of intermediate body centered tetragonal (bct) structure during the bco → fcc transition, which however has been observed or theoretically predicted in solid Br2 and I2. Electron-phonon coupling calculations revealed that solid Cl2 becomes superconductors within bco and fcc phases possessing a highest superconducting temperature of 13.03 K at 380 GPa. We further probed the molecular Cmca → incommensurate phase transition mechanism and found that the softening of the Ag vibrational (rotational) Raman mode in the Cmca phase might be the driving force to initiate the transition.

Electrochemical pesticide detection with AutoDip--a portable platform for automation of crude sample analyses.

PubMed

Drechsel, Lisa; Schulz, Martin; von Stetten, Felix; Moldovan, Carmen; Zengerle, Roland; Paust, Nils

2015-02-07

Lab-on-a-chip devices hold promise for automation of complex workflows from sample to answer with minimal consumption of reagents in portable devices. However, complex, inhomogeneous samples as they occur in environmental or food analysis may block microchannels and thus often cause malfunction of the system. Here we present the novel AutoDip platform which is based on the movement of a solid phase through the reagents and sample instead of transporting a sequence of reagents through a fixed solid phase. A ball-pen mechanism operated by an external actuator automates unit operations such as incubation and washing by consecutively dipping the solid phase into the corresponding liquids. The platform is applied to electrochemical detection of organophosphorus pesticides in real food samples using an acetylcholinesterase (AChE) biosensor. Minimal sample preparation and an integrated reagent pre-storage module hold promise for easy handling of the assay. Detection of the pesticide chlorpyrifos-oxon (CPO) spiked into apple samples at concentrations of 10(-7) M has been demonstrated. This concentration is below the maximum residue level for chlorpyrifos in apples defined by the European Commission.

Modification of structure and pattern of lipid monolayer on water and solid surfaces in presence of globular protein

NASA Astrophysics Data System (ADS)

Sah, Bijay Kumar; Kundu, Sarathi

2017-05-01

Langmuir monolayers of phospholipids at the air-water interface are well-established model systems for mimicking biological membranes and hence are useful for studying lipid-protein interactions. In the present work, phases and phase transformations occurring in the lipid (DMPA) monolayer in the presence of globular protein (BSA) at neutral subphase pH (≈7.0) are highlighted and the corresponding in-plane pattern and morphology are explored from the surface pressure (π) - specific molecular area (A) isotherm, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) both at air-water and air-solid interfaces. Films of pure lipid and lipid-protein complexes are deposited on solid surfaces by Langmuir-Blodgett method. Due to the presence of BSA molecules, phases and domain pattern changes in comparison with that of the pure DMPA. Moreover, accumulations of globular proteins in between lipid domains are also visible through BAM. AFM shows that the mixed film has relatively bigger globular-like morphology in comparison with that of pure DMPA domains. Combination of electrostatic and hydrophobic interactions between protein and lipid are responsible for such modifications.

Coupled discrete element and finite volume solution of two classical soil mechanics problems

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

Chen, Feng; Drumm, Eric; Guiochon, Georges A

One dimensional solutions for the classic critical upward seepage gradient/quick condition and the time rate of consolidation problems are obtained using coupled routines for the finite volume method (FVM) and discrete element method (DEM), and the results compared with the analytical solutions. The two phase flow in a system composed of fluid and solid is simulated with the fluid phase modeled by solving the averaged Navier-Stokes equation using the FVM and the solid phase is modeled using the DEM. A framework is described for the coupling of two open source computer codes: YADE-OpenDEM for the discrete element method and OpenFOAMmore » for the computational fluid dynamics. The particle-fluid interaction is quantified using a semi-empirical relationship proposed by Ergun [12]. The two classical verification problems are used to explore issues encountered when using coupled flow DEM codes, namely, the appropriate time step size for both the fluid and mechanical solution processes, the choice of the viscous damping coefficient, and the number of solid particles per finite fluid volume.« less

New Dioxaborolane Chemistry Enables [18F]-Positron-Emitting, Fluorescent [18F]-Multimodality Biomolecule Generation from the Solid Phase

PubMed Central

Crisp, Jessica L.; Vera, David R.; Tsien, Roger Y.; Ting, Richard

2016-01-01

New protecting group chemistry is used to greatly simplify imaging probe production. Temperature and organic solvent-sensitive biomolecules are covalently attached to a biotin-bearing dioxaborolane, which facilitates antibody immobilization on a streptavidin-agarose solid-phase support. Treatment with aqueous fluoride triggers fluoride-labeled antibody release from the solid phase, separated from unlabeled antibody, and creates [18F]-trifluoroborate-antibody for positron emission tomography and near-infrared fluorescent (PET/NIRF) multimodality imaging. This dioxaborolane-fluoride reaction is bioorthogonal, does not inhibit antigen binding, and increases [18F]-specific activity relative to solution-based radiosyntheses. Two applications are investigated: an anti-epithelial cell adhesion molecule (EpCAM) monoclonal antibody (mAb) that labels prostate tumors and Cetuximab, an anti-epidermal growth factor receptor (EGFR) mAb (FDA approved) that labels lung adenocarcinoma tumors. Colocalized, tumor-specific NIRF and PET imaging confirm utility of the new technology. The described chemistry should allow labeling of many commercial systems, diabodies, nanoparticles, and small molecules for dual modality imaging of many diseases. PMID:27064381

New Dioxaborolane Chemistry Enables [(18)F]-Positron-Emitting, Fluorescent [(18)F]-Multimodality Biomolecule Generation from the Solid Phase.

PubMed

Rodriguez, Erik A; Wang, Ye; Crisp, Jessica L; Vera, David R; Tsien, Roger Y; Ting, Richard

2016-05-18

New protecting group chemistry is used to greatly simplify imaging probe production. Temperature and organic solvent-sensitive biomolecules are covalently attached to a biotin-bearing dioxaborolane, which facilitates antibody immobilization on a streptavidin-agarose solid-phase support. Treatment with aqueous fluoride triggers fluoride-labeled antibody release from the solid phase, separated from unlabeled antibody, and creates [(18)F]-trifluoroborate-antibody for positron emission tomography and near-infrared fluorescent (PET/NIRF) multimodality imaging. This dioxaborolane-fluoride reaction is bioorthogonal, does not inhibit antigen binding, and increases [(18)F]-specific activity relative to solution-based radiosyntheses. Two applications are investigated: an anti-epithelial cell adhesion molecule (EpCAM) monoclonal antibody (mAb) that labels prostate tumors and Cetuximab, an anti-epidermal growth factor receptor (EGFR) mAb (FDA approved) that labels lung adenocarcinoma tumors. Colocalized, tumor-specific NIRF and PET imaging confirm utility of the new technology. The described chemistry should allow labeling of many commercial systems, diabodies, nanoparticles, and small molecules for dual modality imaging of many diseases.

Determination of azoxystrobin residues in grapes, musts and wines with a multicommuted flow-through optosensor implemented with photochemically induced fluorescence.

PubMed

Flores, Javier López; Díaz, Antonio Molina; Fernández de Córdova, María L

2007-02-28

In this paper, the conversion of azoxystrobin in a strongly fluorescent degradation product by UV irradiation with quantitative purposes and its fluorimetric determination are reported for the first time. A multicommuted flow injection-solid phase spectroscopy (FI-SPS) system combined with photochemically-induced fluorescence (PIF) is developed for the determination of azoxystrobin in grapes, must and wine. Grape samples were homogenized and extracted with methanol and further cleaned-up by solid-phase extraction on C(18) silica gel. Wine samples were solid-phase extracted on C(18) sorbent using dichloromethane as eluent. Recoveries of azoxystrobin from spiked grapes (0.5-2.0 mg Kg(-1)), must (0.5-2.0 microg mL(-1)) and wine (0.5-2.0 microg mL(-1)) were 84.0-87.6%, 95.5-105.9% and 88.5-111.2%, respectively. The quantification limit for grapes was 0.021 mg Kg(-1), being within European Union regulations, and 18 microg L(-1) and 8 microg L(-1) for must and wine, respectively.

Theoretical prediction of morphotropic compositions in Na1/2Bi1/2TiO3-based solid solutions from transition pressures

NASA Astrophysics Data System (ADS)

Gröting, Melanie; Albe, Karsten

2014-02-01

In this article we present a method based on ab initio calculations to predict compositions at morphotropic phase boundaries in lead-free perovskite solid solutions. This method utilizes the concept of flat free energy surfaces and involves the monitoring of pressure-induced phase transitions as a function of composition. As model systems, solid solutions of Na1/2Bi1/2TiO3 with the alkali substituted Li1/2Bi1/2TiO3 and K1/2Bi1/2TiO3 and the alkaline earth substituted CaTiO3 and BaTiO3 are chosen. The morphotropic compositions are identified by determining the composition at which the phase transition pressure equals zero. In addition, we discuss the different effects of hydrostatic pressure (compression and tension) and chemical substitution on the antiphase tilts about the [111] axis (a-a-a-) present in pure Na1/2Bi1/2TiO3 and how they develop in the two solid solutions Na1/2Bi1/2TiO3-CaTiO3 and Na1/2Bi1/2TiO3-BaTiO3. Finally, we discuss the advantages and shortcomings of this simple computational approach.

Solid-solution CrCoCuFeNi high-entropy alloy thin films synthesized by sputter deposition

DOE PAGES

An, Zhinan; Jia, Haoling; Wu, Yueying; ...

2015-05-04

The concept of high configurational entropy requires that the high-entropy alloys (HEAs) yield single-phase solid solutions. However, phase separations are quite common in bulk HEAs. A five-element alloy, CrCoCuFeNi, was deposited via radio frequency magnetron sputtering and confirmed to be a single-phase solid solution through the high-energy synchrotron X-ray diffraction, energy-dispersive spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. The formation of the solid-solution phase is presumed to be due to the high cooling rate of the sputter-deposition process.

The effect of the liquid-solid system properties on the interline heat transfer coefficient

NASA Technical Reports Server (NTRS)

Wayner, P. C., Jr.

1977-01-01

A theoretical procedure to determine the heat transfer characteristics of the interline region of an evaporating meniscus using the macroscopic optical and thermophysical properties of the system is outlined. The analysis is based on the premise that the interline transport processes are controlled by the London-van der Waals forces between condensed phases (solid and liquid). The procedure is used to compare the relative size of the interline heat sink of various systems using a constant heat flux model. This solution demonstrates the importance of the interline heat flow number which is evaluated for various systems. The heat transfer characteristics of the decane-steel system are numerically compared with those of the carbon tetrachloride-quartz system.

Quantum phase transition between cluster and antiferromagnetic states

NASA Astrophysics Data System (ADS)

Son, W.; Amico, L.; Fazio, R.; Hamma, A.; Pascazio, S.; Vedral, V.

2011-09-01

We study a Hamiltonian system describing a three-spin-1/2 cluster-like interaction competing with an Ising-like exchange. We show that the ground state in the cluster phase possesses symmetry protected topological order. A continuous quantum phase transition occurs as result of the competition between the cluster and Ising terms. At the critical point the Hamiltonian is self-dual. The geometric entanglement is also studied and used to investigate the quantum phase transition. Our findings in one dimension corroborate the analysis of the two-dimensional generalization of the system, indicating, at a mean-field level, the presence of a direct transition between an antiferromagnetic and a valence bond solid ground state.

Tuning the electrocaloric enhancement near the morphotropic phase boundary in lead-free ceramics

NASA Astrophysics Data System (ADS)

Le Goupil, Florian; McKinnon, Ruth; Koval, Vladimir; Viola, Giuseppe; Dunn, Steve; Berenov, Andrey; Yan, Haixue; Alford, Neil Mcn.

2016-06-01

The need for more energy-efficient and environmentally-friendly alternatives in the refrigeration industry to meet global emission targets has driven efforts towards materials with a potential for solid state cooling. Adiabatic depolarisation cooling, based on the electrocaloric effect (ECE), is a significant contender for efficient new solid state refrigeration techniques. Some of the highest ECE performances reported are found in compounds close to the morphotropic phase boundary (MPB). This relationship between performance and the MPB makes the ability to tune the position of the MPB an important challenge in electrocaloric research. Here, we report direct ECE measurements performed on MPB tuned NBT-06BT bulk ceramics with a combination of A-site substitutions. We successfully shift the MPB of these lead-free ceramics closer to room temperature, as required for solid state refrigeration, without loss of the criticality of the system and the associated ECE enhancement.

Tuning the electrocaloric enhancement near the morphotropic phase boundary in lead-free ceramics

PubMed Central

Le Goupil, Florian; McKinnon, Ruth; Koval, Vladimir; Viola, Giuseppe; Dunn, Steve; Berenov, Andrey; Yan, Haixue; Alford, Neil McN.

2016-01-01

The need for more energy-efficient and environmentally-friendly alternatives in the refrigeration industry to meet global emission targets has driven efforts towards materials with a potential for solid state cooling. Adiabatic depolarisation cooling, based on the electrocaloric effect (ECE), is a significant contender for efficient new solid state refrigeration techniques. Some of the highest ECE performances reported are found in compounds close to the morphotropic phase boundary (MPB). This relationship between performance and the MPB makes the ability to tune the position of the MPB an important challenge in electrocaloric research. Here, we report direct ECE measurements performed on MPB tuned NBT-06BT bulk ceramics with a combination of A-site substitutions. We successfully shift the MPB of these lead-free ceramics closer to room temperature, as required for solid state refrigeration, without loss of the criticality of the system and the associated ECE enhancement. PMID:27312287

Effect of nanostructure on rapid boiling of water on a hot copper plate: a molecular dynamics study

NASA Astrophysics Data System (ADS)

Fu, Ting; Mao, Yijin; Tang, Yong; Zhang, Yuwen; Yuan, Wei

2016-08-01

Molecular dynamic simulations are performed to study the effects of nanostructure on rapid boiling of water that is suddenly heated by a hot copper plate. The results show that the nanostructure has significant effects on energy transfer from solid copper plate to liquid water and phase change process from liquid water to vapor. The liquid water on the solid surface rapidly boil after contacting with an extremely hot copper plate and consequently a cluster of liquid water moves upward during phase change. The temperature of the water film when it separates from solid surface and its final temperature when the system is at equilibrium strongly depend on the size of the nanostructure. These temperatures increase with increasing size of nanostructure. Furthermore, a non-vaporized molecular layer is formed on the surface of the copper plate even continuous heat flux is passing into water domain through the plate.

Synthesis and structural studies on cerium substituted La0.4Ca0.6MnO3 as solid oxide fuel cell electrode material

NASA Astrophysics Data System (ADS)

Singh, Monika; Kumar, Dinesh; Singh, Akhilesh Kumar

2018-04-01

For solid oxide fuel cell electrode material, calcium doped lanthanum manganite La0.4Ca0.6MnO3 (LCMO) and cerium-incorporated on Ca-site with composition La0.40Ca0.55Ce0.05MnO3 (LCCMO) were synthesized using most feasible and efficient glycine-nitrate method. The formation of crystalline single phase was confirmed by x-ray diffraction (XRD). The Rietveld analysis reveals that both systems crystallize into orthorhombic crystal structure with Pnma space group. Additionally, 8 mole % Y2O3 stabilized ZrO2 (8YSZ) solid electrolyte was also synthesized using high energy ball mill to check the reaction with electrode materials. It was found that the substitution of Ce+4 cations in LCMO perovskite suppressed formation of undesired insulating CaZrO3 phase.

Implications for the melting phase relations in the MgO-FeO system at Core-Mantle Boundary conditions

NASA Astrophysics Data System (ADS)

Deng, J.; Lee, K. K. M.

2017-12-01

At nearly 2900 km depth, the core-mantle boundary (CMB) represents the largest density increase within the Earth going from a rocky mantle into an iron-alloy core. This compositional change sets up steep temperature gradients, which in turn influences mantle flow, structure and seismic velocities. Here we compute the melting phase relations of (Mg,Fe)O ferropericlase, the second most abundant mineral in the Earth's mantle, at CMB conditions and find that ultralow-velocity zones (ULVZs) could be explained by solid ferropericlase with 35 < Mg# = 100×(Mg/(Mg+Fe) by mol%) < 65. For compositions outside of this range, a solid ferropericlase cannot explain ULVZs. Additionally, solid ferropericlase can also provide a matrix for iron infiltration at the CMB by morphological instability, providing a mechanism for a high electrical conductivity layer of appropriate length scale inferred from core nutations.

Formation of the Giant Planets by Concurrent Accretion of Solids and Gas

NASA Technical Reports Server (NTRS)

Hubickyj, Olenka

1997-01-01

Models were developed to simulate planet formation. Three major phases are characterized in the simulations: (1) planetesimal accretion rate, which dominates that of gas, rapidly increases owing to runaway accretion, then decreases as the planet's feeding zone is depleted; (2) occurs when both solid and gas accretion rates are small and nearly independent of time; and (3) starts when the solid and gas masses are about equal and is marked by runaway gas accretion. The models applicability to planets in our Solar System are judged using two basic "yardsticks". The results suggest that the solar nebula dissipated while Uranus and Neptune were in the second phase, during which, for a relatively long time, the masses of their gaseous envelopes were small but not negligible compared to the total masses. Background information, results and a published article are included in the report.

Tuning the electrocaloric enhancement near the morphotropic phase boundary in lead-free ceramics.

PubMed

Le Goupil, Florian; McKinnon, Ruth; Koval, Vladimir; Viola, Giuseppe; Dunn, Steve; Berenov, Andrey; Yan, Haixue; Alford, Neil McN

2016-06-17

The need for more energy-efficient and environmentally-friendly alternatives in the refrigeration industry to meet global emission targets has driven efforts towards materials with a potential for solid state cooling. Adiabatic depolarisation cooling, based on the electrocaloric effect (ECE), is a significant contender for efficient new solid state refrigeration techniques. Some of the highest ECE performances reported are found in compounds close to the morphotropic phase boundary (MPB). This relationship between performance and the MPB makes the ability to tune the position of the MPB an important challenge in electrocaloric research. Here, we report direct ECE measurements performed on MPB tuned NBT-06BT bulk ceramics with a combination of A-site substitutions. We successfully shift the MPB of these lead-free ceramics closer to room temperature, as required for solid state refrigeration, without loss of the criticality of the system and the associated ECE enhancement.

Enhancing Modulation of Thermal Conduction in Vanadium Dioxide Thin Film by Nanostructured Nanogaps

DOE PAGES

Choe, Hwan Sung; Suh, Joonki; Ko, Changhyun; ...

2017-08-02

Efficient thermal management at the nanoscale is important for reducing energy consumption and dissipation in electronic devices, lab-on-a-chip platforms and energy harvest/conversion systems. For many of these applications, it is much desired to have a solid-state structure that reversibly switches thermal conduction with high ON/OFF ratios and at high speed. We describe design and implementation of a novel, all-solid-state thermal switching device by nanostructured phase transformation, i.e., modulation of contact pressure an d area between two poly-silicon surfaces activated by microstructural change of a vanadium dioxide (VO 2 ) thin film. Our solid-state devices demonstrate large and reversible alteration ofmore » cross-plane thermal conductance as a function of temperature, achieving a conductance ratio of at least 2.5. This new approach using nanostructured phase transformation provides new opportunities for applications that require advanced temperature and heat regulations.« less

Polydispersity effects in colloid-polymer mixtures.

PubMed

Liddle, S M; Narayanan, T; Poon, W C K

2011-05-18

We study phase separation and transient gelation experimentally in a mixture consisting of polydisperse colloids (polydispersity: ≈ 6%) and non-adsorbing polymers, where the ratio of the average size of the polymer to that of the colloid is ≈ 0.062. Unlike what has been reported previously for mixtures with somewhat lower colloid polydispersity (≈ 5%), the addition of polymers does not expand the fluid-solid coexistence region. Instead, we find a region of fluid-solid coexistence which has an approximately constant width but an unexpected re-entrant shape. We detect the presence of a metastable gas-liquid binodal, which gives rise to two-stepped crystallization kinetics that can be rationalized as the effect of fractionation. Finally, we find that the separation into multiple coexisting solid phases at high colloid volume fractions predicted by equilibrium statistical mechanics is kinetically suppressed before the system reaches dynamical arrest.

Enhancing Modulation of Thermal Conduction in Vanadium Dioxide Thin Film by Nanostructured Nanogaps

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

Choe, Hwan Sung; Suh, Joonki; Ko, Changhyun

Efficient thermal management at the nanoscale is important for reducing energy consumption and dissipation in electronic devices, lab-on-a-chip platforms and energy harvest/conversion systems. For many of these applications, it is much desired to have a solid-state structure that reversibly switches thermal conduction with high ON/OFF ratios and at high speed. We describe design and implementation of a novel, all-solid-state thermal switching device by nanostructured phase transformation, i.e., modulation of contact pressure an d area between two poly-silicon surfaces activated by microstructural change of a vanadium dioxide (VO 2 ) thin film. Our solid-state devices demonstrate large and reversible alteration ofmore » cross-plane thermal conductance as a function of temperature, achieving a conductance ratio of at least 2.5. This new approach using nanostructured phase transformation provides new opportunities for applications that require advanced temperature and heat regulations.« less

The EPOS Implementation Phase: building thematic and integrated services for solid Earth sciences

NASA Astrophysics Data System (ADS)

Cocco, Massimo; Epos Consortium, the

2015-04-01

The European Plate Observing System (EPOS) has a scientific vision and approach aimed at creating a pan-European infrastructure for Earth sciences to support a safe and sustainable society. To follow this vision, the EPOS mission is integrating a suite of diverse and advanced Research Infrastructures (RIs) in Europe relying on new e-science opportunities to monitor and understand the dynamic and complex Earth system. To this goal, the EPOS Preparatory Phase has designed a long-term plan to facilitate integrated use of data and products as well as access to facilities from mainly distributed existing and new research infrastructures for solid Earth Science. EPOS will enable innovative multidisciplinary research for a better understanding of the Earth's physical processes that control earthquakes, volcanic eruptions, ground instability and tsunami as well as the processes driving tectonics and Earth surface dynamics. Through integration of data, models and facilities EPOS will allow the Earth Science community to make a step change in developing new concepts and tools for key answers to scientific and socio-economic questions concerning geo-hazards and geo-resources as well as Earth sciences applications to the environment and to human welfare. Since its conception EPOS has been built as "a single, Pan-European, sustainable and distributed infrastructure". EPOS is, indeed, the sole infrastructure for solid Earth Science in ESFRI and its pan-European dimension is demonstrated by the participation of 23 countries in its preparatory phase. EPOS is presently moving into its implementation phase further extending its pan-European dimension. The EPOS Implementation Phase project (EPOS IP) builds on the achievements of the successful EPOS preparatory phase project. The EPOS IP objectives are synergetic and coherent with the establishment of the new legal subject (the EPOS-ERIC in Italy). EPOS coordinates the existing and new solid Earth RIs within Europe and builds the integrating RI elements. This integration requires a significant coordination between, among others, disciplinary (thematic) communities, national RIs policies and initiatives, as well as geo- and IT-scientists. The RIs that EPOS is coordinating include: i) regionally-distributed geophysical observing systems (seismological and geodetic networks); ii) local observatories (including geomagnetic, near-fault and volcano observatories); iii) analytical and experimental laboratories; iv) integrated satellite data and geological information services v) new services for natural and anthropogenic hazards. Here we present the successful story of the EPOS Preparatory Phase and the progress towards the implementation of both integrated core services (ICS) and thematic core services (TCS) for the different communities participating to the integration plan. We aim to discuss the achieved results and the approach followed to design the implementation phase. The goal is to present and discuss the strategies adopted to foster the implementation of TCS, clarifying their crucial role as domain-specific service hubs for coordinating and harmonizing national resources/plans with the European dimension of EPOS, and their integration to develop the new ICS. We will present the prototype of the ICS central hub as a key contribution for providing multidisciplinary services for solid Earth sciences as well as the glue to keep ICT aspects integrated and rationalized across EPOS. Finally, we will discuss the well-defined role of the EPOS-ERIC Headquarter to coordinate and harmonize national RIs and EPOS services (through ICS and TCS) looking for an effective commitment by national governments. It will be an important and timely opportunity to discuss the EPOS roadmap toward the operation of the novel multidisciplinary platform for discoveries to foster scientific excellence in solid Earth sciences.