Gas adsorption in active carbons and the slit-pore model 1 : pure gas adsorption

We describe procedures based on the polydisperse independent ideal slit-pore model, Monte Carlo simulation and density functional theory (a 'slab-DFT') for predicting gas adsorption and adsorption heats in active carbons.A novel feature of this work is the calibration of gas-surface interactions to a high surface area carbon, rather than to a low surface area carbon as in all previous work. Our models are used to predict the adsorption of carbon dioxide, methane, nitrogen, and hydrogen up to 50 bar in several active carbons at a range of near-ambient temperatures based on an analysis of a single 293 K carbon dioxide adsorption isotherm. The results demonstrate that these models are useful for relatively simple gases at near-critical or supercritical temperatures

Simulating fluid-solid equilibrium with the Gibbs ensemble

The Gibbs ensemble is employed to simulate fluid-solid equilibrium for a shifted-force Lennard-Jones system. This is achieved by generating an accurate canonical Helmholtz free-energy model of the (defect-free) solid phase. This free-energy model is easily generated, with accuracy limited only by finite-size effects, by a single isothermal-isobaric simulation at a pressure not too far from coexistence for which the chemical potential is known. We choose to illustrate this method at the known triple-point because the chemical potential is easily calculated from the coexisting gas. Alternatively, our methods can be used to locate fluid-solid coexistence and the triple-point of pure systems if the chemical potential of the solid phase can be efficiently calculated at a pressure not too far from the actual coexistence pressure. Efficient calculation of the chemical potential of solids would also enable the Gibbs ensemble simulation of bulk solid-solid equilibrium and the grand-canonical ensemble simulation of bulk solids

Gas adsorption in active carbons and the slit-pore model 2 : mixture adsorption prediction with DFT and IAST

We use a fast density functional theory (a 'slab-DFT') and the polydisperse independent ideal slit-pore model to predict gas mixture adsorption in active carbons. The DFT is parametrized by fitting to pure gas isotherms generated by Monte Carlo simulation of adsorption in model graphitic slit-pores. Accurate gas molecular models are used in our Monte Carlo simulations with gas-surface interactions calibrated to a high surface area carbon, rather than a low surface area carbon as in all previous work of this type, as described in part 1 of this work (Sweatman, M. B.; Quirke, N. J. Phys. Chem. B 2005, 109, 10381). We predict the adsorption of binary mixtures of carbon dioxide, methane, and nitrogen on two active carbons up to about 30 bar at near-ambient temperatures. We compare two sets of results; one set obtained using only the pure carbon dioxide adsorption isotherm as input to our pore characterization process, and the other obtained using both pure gas isotherms as input. We also compare these results with ideal adsorbed solution theory (IAST). We find that our methods are at least as accurate as IAST for these relatively simple gas mixtures and have the advantage of much greater versatility. We expect similar results for other active carbons and further performance gains for less ideal mixtures

The density and drag of the accretion wake of a massive body moving through a uniform stellar distribution

We calculate the change in density within a uniform distribution of field stars (point masses) caused by a single massive body passing through with a constant velocity. Starting with the simplest case in which the field stars are initially stationary this leads to an infinite density wake behind the body. Introducing a small thermalisation within the field stars removes this infinity whilst leading to similar results off the path of the massive body. Results are in good agreement with those previously derived. An approximation can be made for the density in the thermalised case and this can be used to deduce the force exerted on the massive body due to the drag caused by the accretion wake

Survey of classical density functionals for modelling hydrogen physisorption at 77 K

This work surveys techniques based on classical density functionals for modeling the quantum dispersion of physisorbed hydrogen at 77 K. Two such techniques are examined in detail. The first is based on the "open ring approximation" (ORA) of Broukhno et al., and it is compared with a technique based on the semiclassical approximation of Feynman and Hibbs (FH). For both techniques, a standard classical density functional is used to model hydrogen molecule-hydrogen molecule (i.e., excess) interactions. The three-dimensional (3D) quantum harmonic oscillator (QHO) system and a model of molecular hydrogen adsorption into a graphitic slit pore at 77 K are used as benchmarks. Density functional results are compared with path-integral Monte Carlo simulations and with exact solutions for the 3D QHO system. It is found that neither of the density functional treatments are entirely satisfactory. However, for hydrogen physisorption studies at 77 K the ORA based technique is generally superior to the FH based technique due to a fortunate cancellation of errors in the density functionals used. But, if more accurate excess functionals are used, the FH technique would be superior

Implementing Lanier's patents for stable, safe and economical ultra-short wing vacu- and para-planes

Backyard Technology are interested in aspects of aircraft design described by Edward H Lanier in a series of six patents obtained from 1930 to 1933. Lanier's overall aim was to provide an exceptionally stable aeroplane that would both fly normally and recover from undesirable attitudes without pilot aid. Backyard Technology were specifically interested in Lanier's idea of creating a vacuum cavity in the wing by replacing a section of the upper skin of the wing with a series of angled slats, believing that this wing design would give superior lift and stability compared to typical wing designs

Kent Sweatman in Senior Composition Recital

This is the program for the senior composition recital of Kent Sweatman. The OBU Chamber Singers, the OBU Brass Choir, and Lee Ann Satterwhite assisted the performance. This recital took place on April 29, 1982, in the Mabee Fine Arts Center Recital Hall

Feeding studies on potential fish predators of post-settlement Acanthaster planci: final report prepared for the Great Barrier Reef Marine Park Authority

[Extract] The general question that prompted this study was whether human exploitation of the fish predators of Acanthaster planci may lead to increased frequency of outbreaks on the GBR

Learning the Host Nation Language While Living Abroad as a Military Adolescent, a Transcendental Phenomenology

High mobility in students has been shown to have a negative effect on academic achievement. Military children relocate six to nine times before graduating high school, with at least one of these moves being overseas. This transcendental phenomenology described the lived experience of military-affiliated students who learned the language of their host culture while living overseas. The theory guiding this study was Ryan and Deci\u27s self-determination theory. This study focused on the importance of self-determination for academic attainment, which is thought to be achieved through a feeling of competence, autonomy, and relatedness. Through criterion sampling, 11 participants, ages18 to 23, who had taken the host nation language to fulfill their high school foreign language requirement while living overseas, were recruited. The study\u27s setting was an Army base in Italy, where all participants attended high school. Data were collected online through one-on-one interviews, reflective essays, and a focus group discussion while simultaneously being analyzed using Epoche, phenomenological reduction, and imaginative variation. The themes identified were disappointment in self, support, home, goals, and outlook. The findings led to the conclusion that military-connected students do not acculturate much, if at all, during their stay in a foreign country due to being surrounded by military culture and thus do not easily acquire the host nation\u27s language. Not meeting the participants\u27 basic needs of competence, autonomy, and relatedness could be a factor that contributes to this. Additional qualitative and quantitative research would be helpful to shed more light on this phenomenon