Temperature-dependent Mass Research Articles

On model for three-dimensional Carreau fluid flow with Cattaneo–Christov double diffusion and variable conductivity: a numerical approach

The present article investigates the steady 3D flow of a Carreau liquid influenced by bidirectional stretching surface. In the presence of Cattaneo–Christov double diffusion with temperature-dependent thermal conductivity, the heat and mass transfer mechanisms have been scrutinized. The alteration of nonlinear PDEs to nonlinear ODEs is equipped via apposite conversions and then resolved numerically by means of bvp4c scheme. The graphical assessment is exposed to portray the essential features of somatic parameters on Carreau liquid temperature and concentration distributions. This study indicates that the variable conductivity parameter enhances the liquid temperature, while the thermal relaxation time parameter and Prandtl number are diminishing functions of temperature field. Furthermore, our results illustrate that the concentration relaxation time parameter and Schmidt number diminish the concentration field. The assertion of present exploration is asserted by emergent assessment with former outcomes vacant in prose, which sets a benchmark for execution of computational methodology. Moreover, graphical assessment is also vacant for two altered techniques, namely analytical (HAM) and numerical (bvp4c).

Thermoplastic Overmolding onto Injection-Molded and In Situ Polymerization-Based Polyamides.

We investigated products manufactured by in situ polymerization, which were reinforced with overmolded ribs. We developed our own mold and prototype product for the project. We used three different materials as preform: a material with a magnesium catalyst, manufactured by in situ polymerization, a Brüggemann AP-NYLON-based in situ polymerization material and an injection-molded PA6 (Durethan B30S, Lanxess GmbH) material. The ribs were formed from the same PA6 material (Durethan B30S, Lanxess GmbH). We examined the effect of the different technological parameters through the pull-off of the overmolded ribs. We measured the effect of melt temperature, holding pressure and holding time, and mold temperature. Considering the individual preforms, we pointed out that monomer migration and binding strength are related, which we concluded from the temperature-dependent mass loss of the materials, measured by thermogravimetric analysis (TGA). Finally, we designed a mold suitable for manufacturing overmolded parts. We designed and built pressure and temperature sensors into the mold to examine and analyze pressures and temperatures around the welding zone of the materials.

Ice nucleation abilities of soot particles determined with the Horizontal Ice Nucleation Chamber

Abstract. Ice nucleation by different types of soot particles is systematically investigated over the temperature range from 218 to 253 K relevant for both mixed-phase (MPCs) and cirrus clouds. Soot types were selected to represent a range of physicochemical properties associated with combustion particles. Their ice nucleation ability was determined as a function of particle size using relative humidity (RH) scans in the Horizontal Ice Nucleation Chamber (HINC). We complement our ice nucleation results by a suite of particle characterization measurements, including determination of particle surface area, fractal dimension, temperature-dependent mass loss (ML), water vapor sorption and inferred porosity measurements. Independent of particle size, all soot types reveal absence of ice nucleation below and at water saturation in the MPC regime (T>235 K). In the cirrus regime (T≤235 K), soot types show different freezing behavior depending on particle size and soot type, but the freezing is closely linked to the soot particle properties. Specifically, our results suggest that if soot aggregates contain mesopores (pore diameters of 2–50 nm) and have sufficiently low water–soot contact angles, they show ice nucleation activity and can contribute to ice formation in the cirrus regime at RH well below homogeneous freezing of solution droplets. We attribute the observed ice nucleation to a pore condensation and freezing (PCF) mechanism. Nevertheless, soot particles without cavities of the right size and/or too-high contact angles nucleate ice only at or well above the RH required for homogeneous freezing conditions of solution droplets. Thus, our results imply that soot particles able to nucleate ice via PCF could impact the microphysical properties of ice clouds.

A sustainable approach for scalable production of α-Fe2O3 nanocrystals with 3D interconnected porous architectures on flexible carbon textiles as integrated electrodes for lithium-ion batteries

Herein, we demonstrate a sustainable strategy for scalable production of α-Fe2O3 nanocrystals on flexible carbon textiles via controllable chemical bath deposition process. The assembly of α-Fe2O3 nanocrystals is densely anchored onto the carbon textiles, and the temperature-dependent mass loading and crystal size of α-Fe2O3 are systematically investigated. As an integrated electrode for lithium-ion batteries, the optimized Fe2O3@CTs with ultrathin three-dimensional interconnected porous architectures achieves significantly enhanced cycling performance and rate capability attributing to the improved stability, electronic interconnection, and shortened solid state diffusion pathway for Li+ ions/electrons. After the reactivation of the precursor, the Li-ion batteries based on the recycled Fe2O3@CTs exhibits electrochemical performance with no decay compared to that of the devices based on the fresh products. This sustainable methodology, considering material abundance, eco-efficiency, synthetic approach and scalability, is of crucial importance to both academy and industry for achieving high-performance lithium-ion batteries.

Gas-Phase Reactions of Carbon Dioxide with Copper Hydride Anions Cu2H2–: Temperature-Dependent Transformation

The hydrogenation of carbon dioxide into value-added chemicals is of great importance for CO2 recycling. However, the underlying mechanism of CO2 hydrogenation remains elusive owing to the lack of experimental evidence for the formation of the C–H bond. Herein, the gas-phase reaction of copper hydride anion Cu2H2– with CO2 at variable temperatures (∼300–560 K) was investigated. Metal hydrides are the ideal models to study the nature of C–H bond formation in CO2 hydrogenation, while the related studies are scarcely reported, particularly for the hydrogenation reactions at temperatures above 300 K. The generation of formate (HCO2–) attached on product CuH2CO2– was identified by temperature-dependent mass spectrometric experiments and density functional theory calculations. Temperature played crucial roles to fine-tune the product selectivity, from Cu2H2CO2– that dominates the room-temperature reaction into CuH2CO2– at elevated temperatures. The nature behind the temperature-dependent product selectivity and...

An extension of Oberbeck–Boussinesq approximation for thermal convection problems

An extension of the Oberbeck–Boussinesq approximation (OB) with expressive thermal effects is investigated to model specific mass with a temperature-dependent approach. An expansion of OB is proposed using a mathematical formulation with null velocity divergence in the continuity equation and variable specific mass in the momentum and energy equations (NOB). The NOB method has been previously tested in the literature, and the present paper aims to carry out a quantitative analysis between NOB and OB. The specific mass is calculated based on the temperature field and a divergence-free velocity is imposed on the NOB due to the small effects of variations of the specific mass in the continuity equation, as previously demonstrated by the OB. The purpose of the NOB is to overcome the OB’s restriction to single-phase flows, as well as to model the effects of specific mass variations more accurately, especially in problems with prominent thermal transfer effects, as that occur in the turbulent regime. Since the effects of a variable specific mass in the momentum and energy equations were taken into account by the NOB, it was expected that the thermal transfer results of the NOB would be improved compared with those of the OB. Then, three-dimensional natural convection simulations for a large range of Rayleigh numbers were performed using OB and NOB in a cubic cavity. Turbulence modeling was performed using Large Eddy Simulation (LES). Numerical results from both approaches were validated and all the results presented good quality. Thermal transfer was evaluated by the calculation of the Nusselt number at the heated wall and compared to experimental data from the literature. The OB and NOB provided adequate thermal transfer rate results; however, the differences between the literature and OB were higher than for NOB. Therefore, NOB is presented as a useful mathematical formulation for modeling incompressible flows with a temperature-dependent specific mass approach in single-phase or multiphase problems instead of solving the full compressible mathematical formulation. In addition, the differences between the literature and OB results increased as the Rayleigh number was raised, especially in the turbulent regime. The results of the NOB were closer to the literature than were those of the OB for the entire range of Rayleigh numbers tested. Therefore, the numerical results confirmed the higher accuracy of NOB compared to OB despite the NOB’s still being an approximate model. Lastly, flow visualization allowed the identification of coherent turbulent structures near the cavity walls in the simulation with Rayleigh number $$10^{10}$$ . The presence of hairpin and Tollmien–Schlichting instabilities revealed the importance of modeling the three-dimensional effects of natural convection in the turbulent regime.

Bulk viscosity of strongly interacting matter in the relaxation time approximation

This paper presents how thermal mean field effects are incorporated consistently in the hydrodynamical modelling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio of the bulk viscosity over its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the $\beta_\lambda$-function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cut-off. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of $\zeta/\tau_R$ for gases obeying Bose-Einstein statistics.

Thermal, Mutual, and Self-Diffusivities of Binary Liquid Mixtures Consisting of Gases Dissolved in n-Alkanes at Infinite Dilution.

In the present study, dynamic light scattering (DLS) experiments and molecular dynamics (MD) simulations were used for the investigation of the molecular diffusion in binary mixtures of liquids with dissolved gases at macroscopic thermodynamic equilibrium. Model systems based on the n-alkane n-hexane or n-decane with dissolved hydrogen, helium, nitrogen, or carbon monoxide were studied at temperatures between 303 and 423 K and at gas mole fractions below 0.06. With DLS, the relaxation behavior of microscopic equilibrium fluctuations in concentration and temperature is analyzed to determine simultaneously mutual and thermal diffusivity in an absolute way. The present measurements document that even for mole gas fractions of 0.007 and Lewis numbers close to 1, reliable mutual diffusivities with an average expanded uncertainty ( k = 2) of 13% can be obtained. By use of suitable molecular models for the mixture components, the self-diffusion coefficient of the gases was determined by MD simulations with an averaged expanded uncertainty ( k = 2) of 7%. The DLS experiments showed that the thermal diffusivity of the studied systems is not affected by the dissolved gas and agrees with the reference data for the pure n-alkanes. In agreement with theory, mutual diffusivities and self-diffusivities were found to be equal mostly within combined uncertainties at conditions approaching infinite dilution of the gas. Our DLS and MD results, representing the first available data for the present systems, reveal distinctly larger mass diffusivities for mixtures containing hydrogen or helium compared to mixtures containing nitrogen or carbon monoxide. On the basis of the broad range of mass diffusivities of the studied gas-liquid systems covering about 2 orders of magnitude from about 10-9 to 10-7 m2·s-1, effects of the solvent and solute properties on the temperature-dependent mass diffusivities are discussed. This contributed to the development of a simple semiempirical correlation for the mass diffusivity of the studied gases dissolved in n-alkanes of varying chain length at infinite dilution as a function of temperature. The generalized expression requiring only information on the kinematic viscosity and molar mass of the pure solvent as well as the molar mass and acentric factor of the solute represents the database from this work and further literature with an absolute average deviation of about 11%.

Anisotropic hydrodynamic modeling of 2.76 TeV Pb-Pb collisions

We compare phenomenological results from 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP) with experimental data collected in LHC 2.76 TeV Pb-Pb collisions. In particular, we present comparisons of particle spectra, average transverse momentum, elliptic flow, and HBT radii. The aHydroQP model relies on the introduction of a single temperature-dependent quasiparticle mass which is fit to lattice QCD data. By taking moments of the resulting Boltzmann equation, we obtain the dynamical equations used in the hydrodynamic stage which include the effects of both shear and bulk viscosities. At freeze-out, we use anisotropic Cooper-Frye freeze-out performed on a fixed-energy-density hypersurface to convert to hadrons. To model the production and decays of the hadrons we use THERMINATOR 2 which is customized to sample from ellipsoidal momentum-space distribution functions. Using smooth Glauber initial conditions, we find very good agreement with many heavy-ion collision observables.

A comparison study on non-isothermal decomposition kinetics of chitosan with different analysis methods

A thermal degradation study of chitosan in air atmosphere has been carried out in detail through Fourier transform infrared (FTIR) analysis, thermogravimetric (TG) analysis and differential thermal analysis (DTA) measurements. FTIR spectra reveal the variations of chemical structures of chitosan in the course of thermal degradation. The mass loss data were collected under the heating rates of 5–30 K min−1. Kinetic analysis of chitosan thermal degradation has been performed through isoconversional FWO, CR, MKN and Tang methods, and the calculated results are basically comparable for these four different methods. With the Arrhenius parameters obtained, the four methods have been attempted to reconstruct the temperature-dependent mass conversion curves and have resulted in generally acceptable results. The TG and DTA results suggest that two-stage thermal degradation processes may be better assumed. For more accurately describing the thermal degradation process of chitosan, the most probable reaction functions have thus been determined for these two stages, leading to greatly improved calculation performance over the entire conversion range. On the basis of the Arrhenius parameter values obtained, the changes in entropy, enthalpy and Gibbs free energy, and lifetime predictions have been estimated concerning the thermal degradation processes of chitosan.

Hydration–Dehydration of Acetonitrile and Methanol in Amorphous Solid Water

The interactions of two model dipolar molecules (acetonitrile (ACN) and methanol (MeOH)) with amorphous solid water (ASW) were investigated using temperature-programmed desorption and temperature-dependent secondary ion mass spectrometry of a series of mixed adlayer thin film systems comprising different configurations of monolayers and thin films of ACN, MeOH, and ASW as well as a nonpolar probe molecule, CO2, deposited on a Ni(111) substrate. The temperature-dependent desorption rates and surface compositions of these systems were found to be consistent with the hydrophobic hydration of ACN, wherein the ACN is caged by water molecules, likely in clathrate-like structures. Consequently, the ACN–water hydrogen bonds are limited to the interior surfaces of the cages. The ACN is not incorporated into the ASW hydrogen bonding network, and it does not modify the crystallization kinetics of the ASW. In contrast, MeOH incorporates into the hydrogen bonding network and modifies the water crystallization kinetics...

Lattice QCD input for axion cosmology

One intriguing beyond-the-Standard-Model particle is the QCD axion, which could simultaneously provide a solution to the Strong $CP$ Problem and account for some, if not all, of the dark matter density in the Universe. This particle is a pseudo-Nambu--Goldstone boson of the conjectured Peccei--Quinn symmetry of the Standard Model. Its mass and interactions are suppressed by a heavy symmetry-breaking scale, ${f}_{a}$, the value of which is roughly greater than ${10}^{9}\text{ }\text{ }\mathrm{GeV}$ (or, conversely, the axion mass, ${m}_{a}$, is roughly less than ${10}^{4}\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$). The density of axions in the Universe, which cannot exceed the relic dark matter density and is a quantity of great interest in axion experiments like ADMX, is a result of the early Universe interplay between cosmological evolution and the axion mass as a function of temperature. The latter quantity is proportional to the second derivative of the temperature-dependent QCD free energy with respect to the $CP$-violating phase, $\ensuremath{\theta}$. However, this quantity is generically nonperturbative, and previous calculations have only employed instanton models at the high temperatures of interest (roughly 1 GeV). In this and future works, we aim to calculate the temperature-dependent axion mass at small $\ensuremath{\theta}$ from first-principle lattice calculations, with controlled statistical and systematic errors. Once calculated, this temperature-dependent axion mass is input for the classical evolution equations of the axion density of the Universe, which is required to be less than or equal to the dark matter density. Due to a variety of lattice systematic effects at the very high temperatures required, we perform a calculation of the leading small-$\ensuremath{\theta}$ cumulant of the theta vacua on large volume lattices for SU(3) Yang--Mills with high statistics as a first proof of concept, before attempting a full QCD calculation in the future. From these pure glue results, the misalignment mechanism yields the axion mass bound ${m}_{a}\ensuremath{\ge}(14.6\ifmmode\pm\else\textpm\fi{}0.1)\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ when Peccei--Quinn breaking occurs after inflation.

Strongly correlated two-dimensional plasma explored from entropy measurements.

Charged plasma and Fermi liquid are two distinct states of electronic matter intrinsic to dilute two-dimensional electron systems at elevated and low temperatures, respectively. Probing their thermodynamics represents challenge because of lack of an adequate technique. Here, we report a thermodynamic method to measure the entropy per electron in gated structures. Our technique appears to be three orders of magnitude superior in sensitivity to a.c. calorimetry, allowing entropy measurements with only 10(8) electrons. This enables us to investigate the correlated plasma regime, previously inaccessible experimentally in two-dimensional electron systems in semiconductors. In experiments with clean two-dimensional electron system in silicon-based structures, we traced entropy evolution from the plasma to Fermi liquid regime by varying electron density. We reveal that the correlated plasma regime can be mapped onto the ordinary non-degenerate Fermi gas with an interaction-enhanced temperature-dependent effective mass. Our method opens up new horizons in studies of low-dimensional electron systems.

A comparison of ice water content measurement techniques on the FAAM BAe-146 aircraft

Abstract. This paper presents a comparison of ice water content (qi) data from a variety of measurement techniques on the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft. Data are presented from a range of cloud types measured during the PIKNMIX field experiment that include mixed-phase stratocumulus, cumulus congestus and cirrus clouds. These measurements cover a broad range of conditions in which atmospheric ice particles are found in nature, such as the low-ice-water-content environments typically found in midlatitude cirrus and the environments with much higher ice water content often observed in cold convective clouds. The techniques include bulk measurements from (i) a Nevzorov hot-wire probe, (ii) the difference between the measured total water content (condensed plus vapour) and the water vapour content of the atmosphere and (iii) a counterflow virtual impactor (CVI) (only for cirrus measurements). We also estimate the qi from integration of the measured particle size distribution (PSD) with assumptions on how the density of ice particles varies as a function of size. The results show that the only bulk ice water content technique capable of measuring high qi values (several g m−3) was the method of total water content minus water vapour. For low ice water contents we develop a new parametrisation of the Nevzorov baseline drift that enables the probe to be sensitive to qi ± 0.002 g m−3. In cirrus clouds the agreement between the Nevzorov and other bulk measurements was typically better than a factor of 2 for the CVI (qi > 0.008 g m−3) and the method of total water content minus water vapour (qi > 0.02 g m−3). Good agreement with the bulk measurements for all cases could be obtained with the estimate from the PSD provided that appropriate a priori assumptions on the mass–dimension relationship were made. This is problematic in the convective clouds sampled because pristine ice particles, heavily rimed particles and supercooled liquid drops were all present. In a cirrus case, we show that using a temperature-dependent mass–dimension relation was required to match the bulk measurement of qi.

Axion cold dark matter: Status after Planck and BICEP2

We investigate the axion dark matter scenario (ADM), in which axions account for all of the dark matter in the Universe, in light of the most recent cosmological data. In particular, we use the Planck temperature data, complemented by WMAP E-polarization measurements, as well as the recent BICEP2 observations of B-modes. Baryon acoustic oscillation data, including those from the baryon oscillation spectroscopic survey, are also considered in the numerical analyses. We find that, in the minimal ADM scenario and for ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{QCD}}=200\text{ }\text{ }\mathrm{MeV}$, the full data set implies that the axion mass ${m}_{\mathrm{a}}=82.2\ifmmode\pm\else\textpm\fi{}1.1\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ [corresponding to the Peccei-Quinn symmetry being broken at a scale ${f}_{\mathrm{a}}=(7.54\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}1{0}^{10}\text{ }\text{ }\mathrm{GeV}$], or ${m}_{\mathrm{a}}=76.6\ifmmode\pm\else\textpm\fi{}2.6\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ [${f}_{\mathrm{a}}=(8.08\ifmmode\pm\else\textpm\fi{}0.27)\ifmmode\times\else\texttimes\fi{}1{0}^{10}\text{ }\text{ }\mathrm{GeV}$] when we allow for a nonstandard effective number of relativistic species ${N}_{\mathrm{eff}}$. We also find a $2\ensuremath{\sigma}$ preference for ${N}_{\mathrm{eff}}>3.046$. The limit on the sum of neutrino masses is $\ensuremath{\sum}{m}_{\ensuremath{\nu}}<0.25\text{ }\text{ }\mathrm{eV}$ at 95% C.L. for ${N}_{\mathrm{eff}}=3.046$, or $\ensuremath{\sum}{m}_{\ensuremath{\nu}}<0.47\text{ }\text{ }\mathrm{eV}$ when ${N}_{\mathrm{eff}}$ is a free parameter. Considering extended scenarios where either the dark energy equation-of-state parameter $w$, the tensor spectral index ${n}_{t}$, or the running of the scalar index $d{n}_{s}/d\mathrm{ln}k$ is allowed to vary does not change significantly the axion mass-energy density constraints. However, in the case of the full data set exploited here, there is a preference for a nonzero tensor index or scalar running, driven by the different tensor amplitudes implied by the Planck and BICEP2 observations. We also study the effect on our estimates of theoretical uncertainties, in particular the imprecise knowledge of the QCD scale ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{QCD}}$, in the calculation of the temperature-dependent axion mass. We find that in the simplest ADM scenario the $\mathrm{Planck}+\mathrm{WP}$ data set implies that the axion mass ${m}_{\mathrm{a}}=63.7\ifmmode\pm\else\textpm\fi{}1.2\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ for ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{QCD}}=400\text{ }\text{ }\mathrm{MeV}$. We also comment on the possibility that axions do not make up for all the dark matter, or that the contribution of string-produced axions has been grossly underestimated; in that case, the values that we find for the mass can conservatively be considered as lower limits. Dark matter axions with mass in the $60--80\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ (corresponding to an axion-photon coupling ${G}_{\mathrm{a}\ensuremath{\gamma}\ensuremath{\gamma}}\ensuremath{\sim}1{0}^{\ensuremath{-}14}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$) range can, in principle, be detected by looking for axion-to-photon conversion occurring inside a tunable microwave cavity permeated by a high-intensity magnetic field, and operating at a frequency $\ensuremath{\nu}\ensuremath{\simeq}15--20\text{ }\mathrm{GHz}$. This is out of the reach of current experiments like the axion dark matter experiment (limited to a maximum frequency of a few GHzs), but is, on the other hand, within the reach of the upcoming axion dark matter experiment-high frequency experiment that will explore the 4--40 GHz frequency range and then be sensitive to axion masses up to $\ensuremath{\sim}160\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$.

Modeling and robust pooling design of a preparative cation-exchange chromatography step for purification of monoclonal antibody monomer from aggregates

This study has implemented and calibrated a model that describes the separation of the monomer of monoclonal antibodies from the dimer and larger oligomers on preparative-scale using cation-exchange chromatography. A general rate model with temperature dependent diffusion was coupled to a pH- and temperature-dependent steric mass action model. The model was shown to predict the retention of the monomer, dimer, and oligomer at low loadings for different pH levels and temperatures. Additionally, the model was shown to adequately predict the elution behavior of the monomer and soluble aggregates at high loadings within the same ranges with some limitations. The model was not able to accurately describe the shape of the product break-through curves or the slight levels of co-elution of the dimer and oligomer with the monomer at higher pH. The model was used to predict how 12 process variations impact the separation. The model is used to establish an elution end collection criterion such that the step can robustly provide the target purity of monomers.

Molecular Model of Self Diffusion in Polar Organic Liquids: Implications for Conductivity and Fluidity in Polar Organic Liquids and Electrolytes

Decades of studying isothermal and temperature-dependent mass and charge transport in polar organic liquids and electrolytes have resulted in two mutually incompatible models and the failure to develop a general molecular level picture. The hydrodynamic model describes conductivity, diffusion, and dielectric relaxation in terms of viscosity, while the inadequacy of the thermal activation model leads to empirical descriptions and fitting procedures whose adjustable parameters have little or no physical significance. We recently demonstrated that transport data can be characterized with a high degree of accuracy and self-consistency using the compensated Arrhenius formalism (CAF), where the transport property of interest assumes an Arrhenius-like form that also includes a dielectric constant dependence in the exponential prefactor. Here, we provide the molecular-level basis for the CAF by first modifying transition state theory, emphasizing the coupling of the diffusing molecule's motion with the dynamical motion of the surrounding matrix. We then explicitly include the polarization energy contribution from the dipolar medium. The polarization energy is related to molecular and system properties through the dipole moment and dipole density, respectively. The energy barrier for transport is coupled to the polarization energy, and we show that accounting for the role of the polarization energy leads naturally to the dielectric constant dependence in the exponential prefactor.

SECOND-ORDER CORRECTIONS TO THE MAGNETIC MOMENT OF ELECTRON AT FINITE TEMPERATURE

Magnetic moment of electron at finite temperature is directly related to the modified electron mass in the background heat bath. Magnetic moment of electron gets modified at finite temperature also, when it couples with the magnetic field, through its temperature-dependent physical mass. We show that the second-order corrections to the magnetic moment of electron is a complicated function of temperature. We calculate the self-mass induced thermal contributions to the magnetic moment of electron, up to the two-loop level, for temperatures valid around the era of primordial nucleosynthesis. A comparison of thermal behavior of the magnetic moment is also quantitatively studied in detail, around the temperatures below and above the nucleosynthesis temperature.

Novel Methodology for the Estimation of Chemical Warfare Agent Mass Transport Dynamics, Part I: Evaporation

A novel contact angle experimental and computational methodology has been developed to estimate mass transport parameters for the evaporation of water and bis(2-chloroethyl) sulfide (distilled mustard, known as the chemical warfare agent HD) on homogeneous, impermeable, substrates of interest. The model uses a finite element technique to simulate the evaporation of a liquid droplet into air. A regression technique is applied to experimental contact angle data to determine the temperature-dependent mass transport parameters (i.e., the diffusivity of the agent in air). The technique predicted the diffusion coefficient for water in air within 1% at 40 °C. The methodology was used to evaluate the evaporation of HD into air at several temperatures, which may be used to develop accurate predictions for vapor emission hazards due to vapor-phase HD. Evaporation of liquid HD generates potential hazards to unprotected personnel. Modeling this process on nonsorptive substrates is the first step toward enable modeling contamination on absorptive substrates. The novel methodology can be applied to other chemicals and therefore may be implemented as a preliminary assessment of the chemicals’ ability to evaporate, which can generate the potential for a chemical vapor hazard. The physics-based models, combined with the generated physical parameter values, enable the prediction of vapor emission hazards from the substrate. The application of this model is intended to simulate chemical warfare agents; however, it is applicable to any liquid on a surface.

Trace anomaly and quasi-particles in finite temperature SU(N) gauge theory

We consider deconfined matter in SU(N) gauge theory as an ideal gas of transversely polarized quasi-particle modes having a temperature-dependent mass m(T). Just above the transition temperature, the mass is assumed to be determined by the critical behavior of the energy density and the screening length in the medium. At high temperature, it becomes proportional to T as the only remaining scale. The resulting (trace anomaly based) interaction measure Delta=(e - 3P)/T^4 and energy density are found to agree well with finite temperature SU(3) lattice calculations.