At the present time there is a lively debate within the nuclear community concerning the relevance of quark degrees of freedom in understanding nuclear structure. We outline the key issues and review the impressive progress made recently within the framework of the quark-meson coupling model. In particular, we explain in quite general terms how the modification of the internal structure of hadrons in-medium leads naturally to three- and four-body forces, or equivalently, to density dependent effective interactions.
abstractNote = {At the present time there is a lively debate within the nuclear community concerning the relevance of quark degrees of freedom in understanding nuclear structure. We outline the key issues and review the impressive progress made recently within the framework of the quark-meson coupling model. In particular, we explain in quite general terms how the modification of the internal structure of hadrons in-medium leads naturally to three- and four-body forces, or equivalently, to density dependent effective interactions.},
There is a measure of debate within the nuclear community concerning the relevance of quark degrees of freedom in understanding nuclear structure. We briefly outline some of the key issues and review the impressive progress made recently within the framework of the quark-meson coupling model. In particular, we explain in quite general terms how the modification of the internal structure of hadrons in-medium leads naturally to three- and four-body forces, or equivalently to density dependent effective interactions.
Elucidation of geodynamic, geochemical, and shock induced processes is limited by challenges to accurately determine molecular fluid equations of state (EOS). High pressure liquid state reactions of carbon species underlie physiochemical mechanisms such as differentiation of planetary interiors, deep carbon sequestration, propellant deflagration, and shock chemistry. In this proceedings paper we introduce a versatile photoacoustic technique developed to measure accurate and precise speeds of sound (SoS) of high pressure molecular fluids and fluid mixtures. SoS of an intermediate boron oxide, HBO{sub 2} are measured up to 0.5 GPa along the 277 C isotherm. A polarized exponential-6 interatomic potential form, parameterizedmore » using our SoS data, enables EOS determinations and corresponding semi-empirical evaluations of >2000 C thermodynamic states including energy release from bororganic formulations. Our thermochemical model propitiously predicts boronated hydrocarbon shock Hugoniot results.« less
Using Fabry-Perot interferometry techniques, we have determined the early time rate of energy release from detonating PETN and TNT explosives filled with 5 to 20 wt % of either 5 {mu}m or 18 {mu}m spherical aluminum with the detonation products, and calculate the extent of reaction at 1--3 {mu}s after the detonation. All of the metal in PETN formulations filled with 5 wt % and 10 wt % of either 5 {mu}m or 18 {mu}m aluminum reacted within 1.5 {mu}s, resulting in an increase of 18--22% in energy compared to pure PETN. For TNT formulations, between 5 to 10 wtmore » % aluminum reacts completely with the same timeframe. A reactive flow hydrodynamic code model based on the Zeldovich-von Neumann-Doring (ZND) description of the reaction zone and subsequent reaction product expansion (Taylor wave) is used to address the reaction rate of the aluminum particles with detonation product gases. The detonation product JWL equation of state is derived from that of pure PETN using a parametric normalization methodology.« less
An equation of state is computed for a plasma of one flavor quarks interacting through some phenomenological potential, in the Hartree approximation, at zero temperature. Assuming that the confining potential is scalar and color-independent, it is shown that the quarks undergo a first-order mass phase transition. In addition, due to the way screening is introduced, all the thermodynamic quantities computed are independent of the actual shape of the interquark potential. This equation of state is then generalized to a potential with scalar and vector components, Fock corrections are discussed and the case of a several quark flavor plasma is studied.more » 19 refs., 2 figs.« less
CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa (Conference) | OSTI.GOV
OSTI.GOV Conference: CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa
Sorption isotherms, which describe the coal’s gas storage capacity, are important for estimating the carbon sequestration potential of coal seams. The DOE-NETL initiated a second inter-laboratory isotherm comparison of coals where CO2 sorption isotherms were collected on moisture-equilibrated coals at temperatures and pressures relevant to CO2 sequestration. Each laboratory used the same coal samples and followed the same general procedure; however, each laboratory used their own apparatus and isotherm measurement technique. This study investigated the inter-laboratory reproducibility of carbon dioxide isotherm measurements on moisture-equilibrated Argonne premium coal samples (Pocahontas #3, Illinois #6, and Beulah Zap). Six independent laboratories provided isotherm data on the three moisture-equilibrated coal samples at 55oC and pressures up to 15 MPa. Agreement among the laboratories was good up to 8 MPa. At the higher pressures, the data among the laboratories diverged significantly for two of the laboratories and coincided reasonably well for four of the laboratories. This work provides guidance for estimating the reproducibility that might be expected when comparing published sorption isotherms on moisture-equilibrated coals from different laboratories.
Goodman, A L. CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa. United States.
abstractNote = {Sorption isotherms, which describe the coal’s gas storage capacity, are important for estimating the carbon sequestration potential of coal seams. The DOE-NETL initiated a second inter-laboratory isotherm comparison of coals where CO2 sorption isotherms were collected on moisture-equilibrated coals at temperatures and pressures relevant to CO2 sequestration. Each laboratory used the same coal samples and followed the same general procedure; however, each laboratory used their own apparatus and isotherm measurement technique. This study investigated the inter-laboratory reproducibility of carbon dioxide isotherm measurements on moisture-equilibrated Argonne premium coal samples (Pocahontas #3, Illinois #6, and Beulah Zap). Six independent laboratories provided isotherm data on the three moisture-equilibrated coal samples at 55oC and pressures up to 15 MPa. Agreement among the laboratories was good up to 8 MPa. At the higher pressures, the data among the laboratories diverged significantly for two of the laboratories and coincided reasonably well for four of the laboratories. This work provides guidance for estimating the reproducibility that might be expected when comparing published sorption isotherms on moisture-equilibrated coals from different laboratories.},
Molecular X-ray scattering measured from two of the Argonne premium coals as a tool for studying polynuclear aromatic hydrocarbons in coals
X-ray scattering techniques were used to gain a better understanding of the structural characteristics of the polynuclear aromatic hydrocarbons in coals. Carbon-carbon distances obtained from Radial Distribution Functions and Pair Correlation Functions agreed well with model distances. Two different calculations of n[sub cc], the average number of nearest neighbor carbons per carbon atom, gave comparable values. For the higher ranked coal an average value of 2.3 was calculated while for the lower carbon content coal, a value of 2.2 was obtained. These values were in the range expected for a substance composed of both aromatic and aliphatic linkages. Separation ofmore » the contributions from aromatic and aliphatic carbon-carbon distances to the first and second peaks in the Pair Correlation Functions showed the higher aromatic content of the higher ranked, higher carbon content coal. Comparison of the experimental data for the coals to model compounds using the Debye Equation showed that the maxima and minima of the experimental curves compared quite well, although the magnitudes did not.« less
A recent general model of coal pyrolysis proposed by the authors' research group has as one of its assumptions that the kinetics of primary product evolution are rank-insensitive. This assumption was tested by a thorough examination of data from experiments where only coal type was varied as well as data from similar experiments in the literature. The conclusion was that, with few exceptions, the kinetic rate constants show little variation with rank. However, this conclusion remains controversial. The Argonne premium samples provide an opportunity to further test this assumption with a set of coals that was designed to cover amore » wide range of coal types. A slow, constant heating rate experiment was used, which is the most sensitive to rate variations. A second controversial area is the importance of heating rate on the volatile product yield and distribution. Evidence has been presented which suggests no intrinsic effect of heating rate on pyrolysis yields and other studies have indicated the converse to be true. However, often these studies have been done under sufficiently different experimental conditions that direct comparisons are difficult. Work has indicated a role for heating rate on tar yields for bituminous coals and on tar molecular weight distributions for lignites. The authors plan to extend this work to the Argonne coals in order to better establish these trends. The current paper is concerned primarily with pyrolysis of the Argonne coals under slow heating conditions in a unique TG-FTIR instrument developed in this laboratory. Results from slow heating rate pyrolysis into a FIMS apparatus are also presented.« less
Infrared spectroscopy is a well-established method of coal characterization. Aspects of coal structure such as functional groups and hydrogen-bonding and changes in structure during pyrolysis and oxidation have been described through infrared analysis and related to macromolecular processes. In particular, Painter et al, have proposed an FTIR procedure for a fairly exhaustive analysis of coal functional groups. Many of these suggestions are incorporated into the present study for the development of a functional group analysis data base for a set of standard coals. Each of the two sampling methods employed here diffuse reflectance infrared (DRIFT) and KBr pellets, have advantagesmore » and drawbacks in coal analysis. DRIFT suffers from a lower signal-to-noise ratio, but is very sensitive to some infrared bands which do not appear well in transmission spectra. DRIFT is especially useful because coal can be sampled without an interfering matrix, which is important in determinations of OH and water content. KBr pellets, on the other hand, offer the advantages of a high signal-to-noise ratio and better control over sample concentration for quantitative work. The strengths of both methods have been exploited in this study.« less
The establishment of the Argonne Premium Sample Bank will allow more meaningful comparisons to be made between pyrolysis studies from different laboratories. This sample bank also provides a good suite of coals for examining rank dependent phenomena, such as the kinetics of primary gas evolution. A recent ''general'' model of coal pyrolysis proposed by our research group has as one of its assumptions that the kinetics of primary product evolution are rank-insensitive. This assumption was tested by a thorough examination of our data from experiments where only coal type was varied as well as data from similar experiments in themore » literature. The conclusion was that, with few exceptions, the kinetic rate constants for individual species evolved from coals pyrolyzed under the same conditions show little variation with rank. However, this conclusion remains controversial. The Argonne premium samples provide an opportunity to further test this assumption with a set of coals that was designed to cover a wide range of coal types. A slow, constant heating rate experiment was used, which is the most sensitive to rate variations. The authors' own work has indicated a role for heating rate on tar yields for bituminous coals and on tar molecular weight distributions for lignites. The authors plan to extend this work to the Argonne coals in order to better establish these trends. The current paper is concerned primarily with pyrolysis of the Argonne coals under slow heating conditions in a unique TG-FTIR instrument developed in the authors' laboratory. Results from slow heating rate pyrolysis into a FIMS apparatus are also presented. Experiments have also been done under rapid heating conditions.« less
The objective of this study is to provide detailed information on the types of nitrogen compounds in coals as a function of rank and age. Desorption high resolution mass spectrometry is being used to examine both whole coals and their pyridine extracts. The authors have shown that nitrogen compounds tend to have larger ring numbers compared to all other aromatic clusters. Now they have found that in low rank coals, such as the subbituminous Wyodak-Anderson, the majority of nitrogen containing compounds have one or more oxygens. The most abundant group of molecules have a nitrogen plus two oxygens and anmore » average ring size of four to five. They have evidence that many of these molecules may be derived from alkaloids. In the higher rank coals, the average ring size increases to seven for the medium volatile Upper Freeport coal. These multiple ring nitrogen compounds play an important role in coal processing and in NO{sub x} production and elimination in combustion.« less
We have linked the structural and dynamic properties in aqueous solution of amphiphilic charged diblock copolymers poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA, synthesized by controlled radical polymerization, with the physico-chemical characteristics of the samples. Despite product imperfections, the samples self-assemble in melt and aqueous solutions as predicted by monodisperse microphase separation theory. However, the PBA core are abnormally large; the swelling of PBA cores is not due to AA (the Flory parameter ?PBA/PAA, determined at 0.25, means strong segregation), but to h-PBA homopolymers (content determined by liquid chromatography at the point of exclusion and adsorption transition, LC-PEAT). Beside the dominant population of micelles detected by scattering experiments, capillary electrophoresis CE analysis permitted detection of two other populations, one of h-PAA, and the other of free PBA-b-PAA chains, that have very short PBA blocks and never self-assemble. Despite the presence of these free unimers, the self-assembly in solution was found out of equilibrium: the aggregation state is history dependant and no unimer exchange between micelles occurs over months (time-evolution SANS). The high PBA/water interfacial tension, measured at 20 mN/m, prohibits unimer exchange between micelles. PBA-b-PAA solution systems are neither at thermal equilibrium nor completely frozen systems: internal fractionation of individual aggregates can occur.
title = {Chemical Analysis and Aqueous Solution Properties of Charged Amphiphilic Block Copolymers PBA-b-PAA Synthesized by MADIX},
author = {Jacquin,M. and Muller, P. and Talingting-Pabalan, R. and Cottet, H. and Berret, J. and Futterer, T. and Theodoly, O.},
abstractNote = {We have linked the structural and dynamic properties in aqueous solution of amphiphilic charged diblock copolymers poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA, synthesized by controlled radical polymerization, with the physico-chemical characteristics of the samples. Despite product imperfections, the samples self-assemble in melt and aqueous solutions as predicted by monodisperse microphase separation theory. However, the PBA core are abnormally large; the swelling of PBA cores is not due to AA (the Flory parameter ?PBA/PAA, determined at 0.25, means strong segregation), but to h-PBA homopolymers (content determined by liquid chromatography at the point of exclusion and adsorption transition, LC-PEAT). Beside the dominant population of micelles detected by scattering experiments, capillary electrophoresis CE analysis permitted detection of two other populations, one of h-PAA, and the other of free PBA-b-PAA chains, that have very short PBA blocks and never self-assemble. Despite the presence of these free unimers, the self-assembly in solution was found out of equilibrium: the aggregation state is history dependant and no unimer exchange between micelles occurs over months (time-evolution SANS). The high PBA/water interfacial tension, measured at 20 mN/m, prohibits unimer exchange between micelles. PBA-b-PAA solution systems are neither at thermal equilibrium nor completely frozen systems: internal fractionation of individual aggregates can occur.},
The interactions of surfactants sodium dodecyl sulfate (SDS), trimethyltetradecylammonium bromide (TTAB), and Triton X-100 with amphiphilic copolymers of acrylamide and dimethyldodecyl(2-acrylamidoethyl)ammonium bromide (DAMAB) have been investigated in aqueous solutions. The rheological properties of a copolymer/surfactant system are affected by both the microstructure of the copolymer and the nature of the surfactant. Addition of the nonionic surfactant, Triton X-100, resulted in a large increase in the reduced viscosity for the microblocky copolymers with 5 mol % DAMAB, while a radon copolymer with the same composition exhibited a collapsed conformation in the presence of the cationic surfactant, TTAB. A strong viscosity enhancementmore » was observed when SDS was added to the solution of a copolymer containing 0.32 mol % DAMAB. Evidence of mixed micelles formed by surfactant molecules and the hydrophobic groups of the copolymers was obtained utilizing surface tension, pyrene probe fluorescence, and viscometry.« less
Surfaces of novel block copolymers with amphiphilic side chains were studied for their ability to influence the adhesion of marine organisms. The surface-active polymer, obtained by grafting fluorinated molecules with hydrophobic and hydrophilic blocks to a block copolymer precursor, showed interesting bioadhesion properties. Two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic surfaces. Both organisms are known to secrete adhesive macromolecules, with apparently different wetting characteristics, to attach to underwater surfaces. The ability of the amphiphilic surface to undergo an environment-dependent transformation in surfacemore » chemistry when in contact with the extracellular polymeric substances is a possible reason for its antifouling nature. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) was used, in a new approach based on angle-resolved X-ray photoelectron spectroscopy (XPS), to determine the variation in chemical composition within the top few nanometers of the surface and also to study the surface segregation of the amphiphilic block. A mathematical model to extract depth-profile information from the normalized NEXAFS partial electron yield is developed.« less
Syntheses of amphiphilic diblock copolymers containing a conjugated block and their self-assembling properties.
Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering
A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. Themore » structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.« less