Part I: Latent heat of vaporization of n-decane. Part II: Heat and mass transfer from a cylinder placed in a turbulent air stream - Sherwood and Frössling numbers as a function of free stream turbulence level and Reynolds number

Part I

The latent heat of vaporization of n-decane is measured calorimetrically at temperatures between 160° and 340°F. The internal energy change upon vaporization, and the specific volume of the vapor at its dew point are calculated from these data and are included in this work. The measurements are in excellent agreement with available data at 77° and also at 345°F, and are presented in graphical and tabular form.

Part II

Simultaneous material and energy transport from a one-inch adiabatic porous cylinder is studied as a function of free stream Reynolds Number and turbulence level. Experimental data is presented for Reynolds Numbers between 1600 and 15,000 based on the cylinder diameter, and for apparent turbulence levels between 1.3 and 25.0 per cent. n-heptane and n-octane are the evaporating fluids used in this investigation.

Gross Sherwood Numbers are calculated from the data and are in substantial agreement with existing correlations of the results of other workers. The Sherwood Numbers, characterizing mass transfer rates, increase approximately as the 0.55 power of the Reynolds Number. At a free stream Reynolds Number of 3700 the Sherwood Number showed a 40% increase as the apparent turbulence level of the free stream was raised from 1.3 to 25 per cent.

Within the uncertainties involved in the diffusion coefficients used for n-heptane and n-octane, the Sherwood Numbers are comparable for both materials. A dimensionless Frössling Number is computed which characterizes either heat or mass transfer rates for cylinders on a comparable basis. The calculated Frössling Numbers based on mass transfer measurements are in substantial agreement with Frössling Numbers calculated from the data of other workers in heat transfer.

Behavior of spherical particles at low Reynolds numbers in a fluctuating translational flow

The behavior of spheres in non-steady translational flow has been studied experimentally for values of Reynolds number from 0.2 to 3000. The aim of the work was to improve our qualitative understanding of particle transport in turbulent gaseous media, a process of extreme importance in power plants and energy transfer mechanisms.

Particles, subjected to sinusoidal oscillations parallel to the direction of steady translation, were found to have changes in average drag coefficient depending upon their translational Reynolds number, the density ratio, and the dimensionless frequency and amplitude of the oscillations. When the Reynolds number based on sphere diameter was less than 200, the oscillation had negligible effect on the average particle drag.

For Reynolds numbers exceeding 300, the coefficient of the mean drag was increased significantly in a particular frequency range. For example, at a Reynolds number of 3000, a 25 per cent increase in drag coefficient can be produced with an amplitude of oscillation of only 2 per cent of the sphere diameter, providing the frequency is near the frequency at which vortices would be shed in a steady flow at the mean speed. Flow visualization shows that over a wide range of frequencies, the vortex shedding frequency locks in to the oscillation frequency. Maximum effect at the natural frequency and lock-in show that a non-linear interaction between wake vortex shedding and the oscillation is responsible for the increase in drag.

Turbulent buoyant jets into stratified or flowing ambient fluids

Theoretical and experimental studies were made on two classes of buoyant jet problems, namely:

1) an inclined, round buoyant yet in a stagnant environment with linear density-stratification;

2) a round buoyant jet in a uniform cross stream of homogenous density.

Using the integral technique of analysis, assuming similarity, predictions can be made for jet trajectory, widths, and dilution ratios, in a density-stratified or flowing environment. Such information is of great importance in the design of disposal systems for sewage effluent into the ocean or waste gases into the atmosphere.

The present study of a buoyant jet in a stagnant environment has extended the Morton type of analysis to cover the effect of the initial angle of discharge. Numerical solutions have been presented for a range of initial conditions. Laboratory experiments were conducted for photographic observations of the trajectories of dyed jets. In general the observed jet forms agreed well with the calculated trajectories and nominal half widths when the value of the entrainment coefficient was taken to be α = 0.082, as previously suggested by Morton.

The problem of a buoyant jet in a uniform cross stream was analyzed by assuming an entrainment mechanism based upon the vector difference between the characteristic jet velocity and the ambient velocity. The effect of the unbalanced pressure field on the sides of the jet flow was approximated by a gross drag term. Laboratory flume experiments with sinking jets which are directly analogous to buoyant jets were performed. Salt solutions were injected into fresh water at the free surface in a flume. The jet trajectories, dilution ratios and jet half widths were determined by conductivity measurements. The entrainment coefficient, α, and drag coefficient, C_d, were found from the observed jet trajectories and dilution ratios. In the ten cases studied where jet Froude number ranged from 10 to 80 and velocity ratio (jet: current) K from 4 to 16, α varied from 0.4 to 0.5 and C_d from 1.7 to 0.1. The jet mixing motion for distance within 250D was found to be dominated by the self-generated turbulence, rather than the free-stream turbulence. Similarity of concentration profiles has also been discussed.

Studies of noble gases in meteorites and in the earth

The isotopic and elemental abundances of noble gases in the solar system are investigated, using simple mixing models and mass-spectrometric measurements of the noble gases in meteorites and terrestrial rocks and minerals.

Primordial neon is modeled by two isotopically distinct components from the interstellar gas and dust. Neon from the gas dominates solar neon, which contains about ten times more ²⁰Ne than ²²Ne. Neon from the dust is represented in meteorites by neon-E, with ²⁰Ne/²²Ne less than 0.6. Isotopic variations in meteorites require neon from both dust and gas to be present. Mixing dust and gas without neon loss generates linear correlation lines on three-isotope and composition-concentration diagrams. A model for solar wind implantation predicts small deviations from linear mixing, due to preferential sputtering of the lighter neon isotopes.

Neon in meteorites consists of galactic cosmic ray spallation neon and at least two primordial components, neon-E and neon-S. Neon was measured in several meteorites to investigate these end- members. Cosmogenic neon produced from sodium is found to be strongly enriched in ²²Ne. Neon measurements on sodium-rich samples must be interpreted with care so not to confuse this source of ²²Ne with neon-E, which is also rich in ²²Ne.

Neon data for the carbonaceous chondrite Mokoia show that the end member composition of neon-Si in meteorites is ²⁰Ne/²²Ne = 13.7, the same as the present solar wind. The solar wind composition evidently has remained constant since before the compaction of Mokoia.

Ca, Al-rich inclusions from the Allende meteorite were examined for correlation between neon-E and oxygen or magnesium isotopic anomalies. ²²Ne and ³⁶Ar enrichments found in some inclusions are attributed to cosmic- ray-induced reactions on Na and Cl, not to a primordial component. Neon-E is not detectably enriched in Allende.

Measurements were made to determine the noble gas contents of various terrestrial rocks and minerals, and to investigate the cycling of noble gases between different terrestrial reservoirs. Beryl crystals contain a characteristic suite of magmatic gases including nucleogenic ²¹Ne and ²²Ne from (α,n) reactions, radiogenic ⁴⁰Ar, and fissiogenic ^131-136Xe from the decay of K and U in the continental crust. Significant concentrations of atmospheric noble gases are also present in beryl.

Both juvenile and atmospheric noble gases are found in rocks from the Skaergaard intrusion. The ratio ⁴⁰Ar/³⁶Ar (corrected for in situ decay of ⁴⁰K) correlates with δ¹⁸O in plagioclase. Atmospheric argon has been introduced into samples that have experienced oxygen-isotope exchange with circulating meteoric hydrothermal fluids. Unexchanged samples contain juvenile argon with ⁴⁰Ar/³⁶Ar greater than 6000 that was trapped from the Skaergaard magma.

Juvenile and atmospheric gases have been measured in the glassy rims of mid-ocean ridge (MOR) pillow basalts. Evidence is presented that three samples contain excess radiogenic ¹²⁹Xe and fission xenon, in addition to the excess radiogenic ⁴⁰Ar found in all samples. These juvenile gases are being outgassed from the upper-mantle source region of the MOR magma. No isotopic evidence has been found here for juvenile primordial noble gases accompanying the juvenile radiogenic gases in the MOR glasses. Large argon isotopic variations in a single specimen provide a clear indication of the late-stage addition of atmospheric argon, probably from seawater.

The Skaergaard data demonstrate that atmospheric noble gases dissolved in ground water can be transferred into crustal rocks. Subduction of oceanic crust altered by seawater can transport atmospheric noble gases into the upper mantle. A substantial portion of the noble gases in mantle derived rocks may represent subducted gases, not a primordial component as is often assumed.

1. Ultrasonic studies of binary liquid structure in the critical region. Theory and experiment for the 2,6-lutidine/water system. 2. Hartree-Fock calculations of electric polarizabilities of some simple atoms and molecules, and their practicality. 3. Calculation of vibrational transition probabilities in collinear atom-diatom and diatom-diatom collisions with Lennard-Jones interaction

Part 1. Many interesting visual and mechanical phenomena occur in the critical region of fluids, both for the gas-liquid and liquid-liquid transitions. The precise thermodynamic and transport behavior here has some broad consequences for the molecular theory of liquids. Previous studies in this laboratory on a liquid-liquid critical mixture via ultrasonics supported a basically classical analysis of fluid behavior by M. Fixman (e. g., the free energy is assumed analytic in intensive variables in the thermodynamics)--at least when the fluid is not too close to critical. A breakdown in classical concepts is evidenced close to critical, in some well-defined ways. We have studied herein a liquid-liquid critical system of complementary nature (possessing a lower critical mixing or consolute temperature) to all previous mixtures, to look for new qualitative critical behavior. We did not find such new behavior in the ultrasonic absorption ascribable to the critical fluctuations, but we did find extra absorption due to chemical processes (yet these are related to the mixing behavior generating the lower consolute point). We rederived, corrected, and extended Fixman's analysis to interpret our experimental results in these more complex circumstances. The entire account of theory and experiment is prefaced by an extensive introduction recounting the general status of liquid state theory. The introduction provides a context for our present work, and also points out problems deserving attention. Interest in these problems was stimulated by this work but also by work in Part 3.

Part 2. Among variational theories of electronic structure, the Hartree-Fock theory has proved particularly valuable for a practical understanding of such properties as chemical binding, electric multipole moments, and X-ray scattering intensity. It also provides the most tractable method of calculating first-order properties under external or internal one-electron perturbations, either developed explicitly in orders of perturbation theory or in the fully self-consistent method. The accuracy and consistency of first-order properties are poorer than those of zero-order properties, but this is most often due to the use of explicit approximations in solving the perturbed equations, or to inadequacy of the variational basis in size or composition. We have calculated the electric polarizabilities of H₂, He, Li, Be, LiH, and N₂ by Hartree-Fock theory, using exact perturbation theory or the fully self-consistent method, as dictated by convenience. By careful studies on total basis set composition, we obtained good approximations to limiting Hartree-Fock values of polarizabilities with bases of reasonable size. The values for all species, and for each direction in the molecular cases, are within 8% of experiment, or of best theoretical values in the absence of the former. Our results support the use of unadorned Hartree-Pock theory for static polarizabilities needed in interpreting electron-molecule scattering data, collision-induced light scattering experiments, and other phenomena involving experimentally inaccessible polarizabilities.

Part 3. Numerical integration of the close-coupled scattering equations has been carried out to obtain vibrational transition probabilities for some models of the electronically adiabatic H₂-H₂ collision. All the models use a Lennard-Jones interaction potential between nearest atoms in the collision partners. We have analyzed the results for some insight into the vibrational excitation process in its dependence on the energy of collision, the nature of the vibrational binding potential, and other factors. We conclude also that replacement of earlier, simpler models of the interaction potential by the Lennard-Jones form adds very little realism for all the complication it introduces. A brief introduction precedes the presentation of our work and places it in the context of attempts to understand the collisional activation process in chemical reactions as well as some other chemical dynamics.

Atividade pró-trombótica da toxina ExoU de Pseudomonas aeruginosa detectada em modelos experimentais in vivo e in vitro

Pseudomonas aeruginosa é um importante agente de pneumonia, particularmente em pacientes submetidos à ventilação mecânica, que pode evoluir para sepse, com elevadas taxas de letalidade. Na sepse, o processo inflamatório sistêmico exacerbado favorece o desequilíbrio entre as vias de coagulação e fibrinólise e a instalação de um estado pró-coagulante, com o aparecimento de trombose microvascular, coagulação intravascular disseminada e falência de múltiplos órgãos. Conhecendo a potente atividade pró-inflamatória da toxina ExoU produzida por P. aeruginosa, decorrente de sua atividade fosfolipásica A2, o objetivo desta tese foi investigar seu potencial de indução de alterações hemostáticas relacionadas à patogênese da sepse. Utilizando modelo de sepse em camundongos inoculados, por via intratraqueal, com suspensões de P. aeruginosa produtora de ExoU (PA103) ou de cepa com deleção do gene exoU, não produtora da toxina, foi mostrado que ExoU determinou maior gravidade da infecção, maior taxa de letalidade, leucopenia, trombocitose, hiperpermeabilidade vascular e transudação plasmática, evidenciadas, respectivamente, pela maior concentração de proteínas nos lavados broncoalveolares (LBAs) e acúmulo do corante Azul de Evans, previamente inoculado nos animais, por via endovenosa, no parênquima renal. ExoU favoreceu, também, a ativação plaquetária, confirmada pela maior concentração de plaquetas expressando P-selectina em sua superfície, maior número de micropartículas derivadas de plaquetas e maior concentração plasmática de tromboxano A2. A histopatologia dos pulmões e rins dos animais infectados com PA103 confirmou a formação de microtrombos, que não foram detectados nos animais controles ou infectados com a cepa mutante. Nos pulmões, a produção de ExoU determinou intensa resposta inflamatória com maior concentração de leucócitos totais e polimorfonucleados, interleucina-6 e fator de necrose tumoral-α nos LBAs. A análise imunohistoquímica mostrou intensa deposição de fibrina nos alvéolos e septos interalveolares. A atividade pró-coagulante dependente do fator tissular detectada nos LBAs dos camundongos infectados com PA103 foi independente da produção do inibidor da via de ativação do fator tissular (TFPI), mas associada ao aumento da produção do inibidor do ativador do plasminogênio-1 (PAI-1). Para investigar a participação do fator de ativação plaquetária (PAF) na liberação de PAI-1, foi pesquisada a atividade da enzima PAF-acetil-hidrolase (PAF-AH) nos LBAs dos camundongos. A atividade de PAF-AH apresentou-se significativamente elevada nos LBA dos camundongos infectados com PA103. O tratamento dos animais com um inibidor do PAF, antes da infecção, resultou na diminuição significativa das concentrações de PAI-1 e de leucócitos totais, bem como da atividade pró-coagulante dos LBAs. In vitro, ExoU induziu maior expressão do RNA mensageiro de PAI-1 e maior liberação da proteína PAI-1 nos sobrenadantes de células epiteliais respiratórias da linhagem A549. O tratamento das células A549 com um anticorpo anti-receptor de PAF, antes da infecção, reduziu significativamente a concentração de PAI-1 nos sobrenadantes de células infectadas com a cepa selvagem. Estes resultados demonstraram um novo mecanismo de virulência de P. aeruginosa através da atividade pró-trombótica de ExoU e a possibilidade de utilização da identificação de ExoU em isolados clínicos de pacientes graves como um marcador prognóstico para estes pacientes.

Self-Similarity and helical symmetry in vortex generator flow simulations

According to experimental observations, the vortices generated by vortex generators have previously been observed to be self-similar for both the axial (u(z)) and azimuthal (u(circle minus)) velocity profiles. Further, the measured vortices have been observed to obey the criteria for helical symmetry. This is a powerful result, since it reduces the highly complex flow to merely four parameters. In the present work, corresponding computer simulations using Reynolds-Averaged Navier-Stokes equations have been carried out and compared to the experimental observations. The main objective of this study is to investigate how well the simulations can reproduce the physics of the flow and if the same analytical model can be applied. Using this model, parametric studies can be significantly reduced and, further, reliable simulations can substantially reduce the costs of the parametric studies themselves.