A study of the structure of jet turbulence producing jet noise

Characteristics of turbulent structure of mixing region near outlet of circular subsonic jet and production of jet nois

Biodistribution and PET Imaging of pharmacokinetics of manganese in mice using Manganese-52

<div><p>Manganese is essential to life, and humans typically absorb sufficient quantities of this element from a normal healthy diet; however, chronic, elevated ingestion or inhalation of manganese can be neurotoxic, potentially leading to <i>manganism</i>. Although imaging of large amounts of accumulated Mn(II) is possible by MRI, quantitative measurement of the biodistribution of manganese, particularly at the trace level, can be challenging. In this study, we produced the positron-emitting radionuclide ⁵²Mn (<i>t</i>_<i>1/2</i> = 5.6 d) by proton bombardment (<i>E</i>_<i>p</i><15 MeV) of chromium metal, followed by solid-phase isolation by cation-exchange chromatography. An aqueous solution of [⁵²Mn]MnCl₂ was nebulized into a closed chamber with openings through which mice inhaled the aerosol, and a separate cohort of mice received intravenous (IV) injections of [⁵²Mn]MnCl₂. <i>Ex vivo</i> biodistribution was performed at 1 h and 1 d post-injection/inhalation (p.i.). In both trials, we observed uptake in lungs and thyroid at 1 d p.i. Manganese is known to cross the blood-brain barrier, as confirmed in our studies following IV injection (0.86%ID/g, 1 d p.i.) and following inhalation of aerosol, (0.31%ID/g, 1 d p.i.). Uptake in salivary gland and pancreas were observed at 1 d p.i. (0.5 and 0.8%ID/g), but to a much greater degree from IV injection (6.8 and 10%ID/g). In a separate study, mice received IV injection of an imaging dose of [⁵²Mn]MnCl₂, followed by <i>in vivo</i> imaging by positron emission tomography (PET) and <i>ex vivo</i> biodistribution. The results from this study supported many of the results from the biodistribution-only studies. In this work, we have confirmed results in the literature and contributed new results for the biodistribution of inhaled radiomanganese for several organs. Our results could serve as supporting information for environmental and occupational regulations, for designing PET studies utilizing ⁵²Mn, and/or for predicting the biodistribution of manganese-based MR contrast agents.</p></div

Sound attenuation in a condensing vapor

The process of acoustic attenuation in a condensing medium is investigated using a continuumlike formulation that allows for the phase-exchange process. The liquid phase is assumed sufficiently disperse so that the field may be treated as a continuum. The elementary relaxation processes associated with droplet velocity, temperature, and vapor pressure equilibration are equally important in determining the attenuation when vapor, liquid, and inert gas mass fractions are of the same order. When the liquid mass fraction is small, however, a strong attenuation band appears at low frequencies. This attenuation process involves a coupled relaxation process in which heat transfer and vaporization processes combine to change the temperature of the relatively large gas mass. This attenuation band (i) centers on a frequency that is proportional to the concentration of liquid, and (ii) has a maximum value that varies directly as the concentration of condensible vapor and roughly as the square of the latent heat of vaporization. When the concentrations of liquid and condensible vapor are both small, the low-frequency attenuation band is nearly isolated and may be described in a convenient analytical manner

Wood Property Variation of Mississippi Delta Hardwoods

Variation in specific gravity, fiber length, fiber dimensions, and volumetric composition were investigated for selected heights and growth rings of five Mississippi Delta hardwood species: black willow, willow oak, sycamore, pecan, and sugarberry. Variation of specific gravity with age of the cambium was not only different from species to species, but was also different at different sampling heights. The fiber length-age relationship in study trees conformed to the general pattern of large increases in fiber length with age in rings near the pith, followed by a more gradual increase until a maximum was reached. Variations in fiber diameter were not great, but in all species, cell diameter decreased as height in the stem increased. Thin-walled fibers were found near the pith and thick-walled fibers developed in the outermost growth increments.Volumetric composition data revealed large variations between sampling points. The general pattern with age was a linear or curvilinear increase in vessel volume with a corresponding decrease in fiber volume, while ray volume remained constant or increased slightly with age.Correlation analysis was used to evaluate the interrelationships of measured properties in three different species (willow, sugarberry, and pecan). Wide growth rings in these species contained proportionately fewer vessels and more fibers than narrow growth rings as well as shorter fibers. High specific gravity was associated with increased fiber volume. However, the analysis showed no significant differences in specific gravity resulting from variations in growth rate

The Temporary Construction of Consumer Attitudes

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141498/1/jcpy375.pd