Droplets Of Various Sizes Research Articles

Characterization of Slag-Metal Droplet-Gas Emulsion in Oxygen Steelmaking Converters.

Metal droplets of various sizes are ejected from the jet impact zone in oxygen steel making converters. The residence time of these droplets in the surrounding gas-slag mixture is calculated for different operating conditions in top blown converters. A new dimensionless emulsion number, En, based on the ratio of the residence time of the metal droplets to the residence time of gas bubbles in liquid slag is proposed. This emulsion number is found to be strongly dependent on the ratio of lance height to the throat diameter of De Laval nozzle. The blowing regimes followed in three plants are analyzed in terms of emulsion number. The reduction of FeO in slag by dissolved carbon in metal droplets also depends upon emulsion number and, in turn, decides the lance height chosen at various stages of the blow as well as lime dissolution, slag formation and slopping. The emulsion number can be used as an effective tool to control slag formation behaviour.

Literature Review: The Common Cold

Most colds are caused by rhinovirus infection, perhaps facilitated by chilling or stress. Virus infection begins in the nasopharynx and causes spotty destruction of the nasal ciliated epithelium. Transmission occurs chiefly via droplets of various sizes transported through the air, but some types of virus persist in moist secretions on handled objects and may retain their infectiousness. Living in crowded, poorly-ventilated quarters facilitates transmission. Not many virus particles survive in saliva and it is difficult to infect via the lips or mouth. Kissing does not efficiently spread cold infection. Prophylactic treatment with interferon does not protect against cold infection. Aspirin and acetaminophen reduced serum antibody response and increased nasal symptoms in a controlled Australian study. The combination of intranasal interferon and ipratropium with oral naproxen gave promising results in experimental rhinovirus inoculation. Basically, there has been little or no progress towards effective cold treatment in the past century.

Ultrastructural Studies on the Uropygial Glands of Quail.

To investigate the processes of lipid synthesis and secretion of the uropygial gland of the adult male quail, glandular cells of the shallow and deep portions of the secretory tubule were observed ultrastructurally. All glandular cells in the shallow and deep portions displayed a lamellar structure, which was divided into basal, transitional and degenerating layers. In the shallow portion, some glandular cells in the transitional layer contained small lipid droplets, and others conspicuously large lipid droplets. Both cell types had a well-developed lamellar smooth endoplasmic reticulum (sER), and a well-developed Golgi apparatus. The former cells also contained sER with a lattice structure in the middle. In the degenerating layer, the glandular cells had many lipid droplets of moderate size and organellar structure had been lost due to autolysis. In the deep portion of the secretory tubule, the glandular cells of the transitional layer were filled with lipid droplets of various sizes which were surrounded by well-developed follicular or rod sER in which organella such as Golgi apparatus were also well developed. Rhombic crystalline structures were also observed. The glandular cells of the degenerating layer displayed a tendency to assemble lipid droplets of various sizes which compressed the nuclei to a stellate appearance. The structures of the sER and Golgi apparatus were well maintained, while the mitochondria were degenerated.These results suggest that lipid in the quail uropygial gland is synthesized in the sER and Golgi apparatus of glandular cells of the transitional layer, and particularly in the deep rather than the shallow portions.

Derivation of near-field sectional equations for the dynamics of polydisperse spray flows: An analysis of the relaxation zone behind a normal shock wave

A gas flow field behind a normal shock wave inflicts a step function in velocity, temperature, and pressure upon a polydisperse spray suspended in the flow. As a result, there are large differences in velocity and temperature between the carrying gas and the droplets of the spray immediately after the shock. These differences gradually decrease in a relaxation zone which ends at a distance, where the so-called far-field begins, at which the droplets eventually travel at a velocity which is close to the host fluid velocity. Thus, the investigation of the relaxation zone may be regarded as the analysis of a near-field problem in contradistinction to far-field problems that have been analyzed by Greenberg, Tambour and their coworkers employing a sectional approach. Treatment of a near-field problem via a sectional approach requires derivation of new generalized sectional-equations that extend the previous sectional-equations that were derived by Tambour for far-field problems. Such new generalized sectional-equations are derived in the present paper. They rigorously account for the heritage of momentum and enthalpy that droplets carry with them as they “move” from one size section to another due to evaporation and coalescence processes, for example, a large droplet formed by coalescence (of two small droplets) will differ from the originally large droplets since the properties of the newly formed droplet depend on the properties of the small droplets which participate in the coalescence process, and generally in the near-field, small droplets differ in velocity and enthalpy from large ones. These effects, as well as the influence of the velocity lag between droplets and the most fluid, between droplets of various sizes, and between droplets of the same size on the evolution in pointwise droplet size distributions along the axial direction are presented here. The computed results also include changes of velocities and temperatures of each droplet size-section in the relaxation zone.

Sea spray dispersion over the ocean surface: A numerical simulation

A trajectory simulation approach has been used to calculate sea spray dispersion above the ocean surface as a function of droplet size, emission rate, and meteorological conditions. By numerically simulating the stochastic turbulent trajectories of a large number of ejected sea spray droplets of various sizes and ejection speeds, the vertical profile of sea spray concentration was deduced from the average residence time of the droplets in each of a set of horizontal layers within the first 10 m above the ocean surface.

A case study in intermittency: The Thermodynamic Model for intermediate energy heavy ion collisions

The Thermodynamic Model for heavy ion collisions explains, at least semi-quantitatively, many, though not all, features of the experimental data at Bevalac energies. We use this model as a case study for intermittency. A composite with n nucleons and total momentum P will be registered at the detector as n nucleons each with momentum P/ n. We find that in this model the scaled factorial moments grow indefinitely with M where M is the number of divisions in the p z window. In so far as composites are droplets of various sizes (free nucleons constitute a gas), intermittency is seen to be linked to the existence of droplets. The role of resonances is examined by including excited “deuterons” whose mass determines the width of the momentum distribution of the decay nucleons. For nucleons and resonances only, the scaled factorial moments saturate with M when the bin size becomes smaller than the width. These results do not depend upon the size of the colliding systems thus the model cannot explain why, for example, e + e − shows stronger intermittency than the currently available heavy ion data.

Cyclic AMP-Receptor Protein Activity in Rat Preputial Cells

Cells from the rat preputial gland--a type of sebaceous gland--exhibited specific responsiveness of cyclic 3',5'-adenosine monophosphate (AMP) dependent protein kinase to stimulation by agents that elevate intracellular cyclic AMP. Electron microscopy shows that the rat preputial gland resembles the human sebaceous gland, not only in terms of containing a sebocyte-like population of cells in an acinar arrangement at different maturational stages, but also in the morphology of its organelles such as abundant and sometimes atypical mitochondria, many perinuclear lysosomes with crystalline inclusions, lipid droplets of various sizes, and peroxisomes. Other cell types, among them duct and inflammatory cells, were evident in the tissue sections, but constituted a minor component. Responses to stimulation of the adenylate cyclase-protein kinase pathways were determined using preputial cells that had been both freshly dispersed and grown in monolayer culture. Stimulation with isoproterenol (IPR) or forskolin (FS) resulted in both cases in an increase of cyclic AMP binding of the regulatory (R) subunits of cyclic AMP-dependent protein kinase, as determined by photoaffinity labeling of R subunits with an azido analog of cyclic AMP ([32P]-8-azido cyclic AMP). Cells from the epidermis under comparable conditions responded to a lesser degree and with a different distribution of R subunit isoforms. There are, therefore, differences in receptor activity as well as in the transduction pathways between the two types of epithelial cell populations. These results indicate that the preputial gland contains precursor cells that differentiate in culture to retain specific molecular mechanisms of action mediated via cyclic AMP.

Vacancy supersaturation in rapidly solidified metal droplets.

A self-consistent theory for vacancy entrapment in rapidly solidified metal droplets is presented. Supersaturation occurs when excess (nonequilibrium) vacancies created at the solidification front by the liquid-solid density difference are unable to diffuse back to the interface before the droplet solidifies. The model consists of heat-conduction equations for the liquid and solid phases, a vacancy-diffusion equation, and boundary conditions at the internal and external surfaces that provide coupling between regions and generate the interface dynamics and vacancy entrapment. Solutions to this system of equations are derived in the form of a set of integral equations that incorporate the boundary conditions as integral kernels. These are evaluated numerically to produce temperature and vacancy-concentration profiles for rapidly solidified droplets of various sizes, initial undercoolings, and convective cooling rates. For undercooled, micrometer-sized metal droplets, the model gives vacancy concentrations at solidification far in excess of equilibrium values.

Tem studies of coal tars: Crude tar and its insoluble fractions

Tars as issued from a coking plant were characterized by Transmission Electron Microscopy (TEM). A method of microtomy allowing tars to be thin-sectioned was perfected. The microtextural data obtained are compared to those obtained from anthracene-oil insolubles (AOI) also prepared by thin section and to those obtained from ground AOI. Crude tars are constituted of droplets of various sizes and shapes, either clean or including other phases such as carbon blacks (in majority) and spheres with radial or alternate textures (concentric and then radial). Clean droplets are γ resins (toluene soluble). Droplets containing other phases are γ resins only in their skin and β resins (toluene insoluble but quinoline soluble) in the areas in contact with carbon blacks or spheres. No Brooks and Taylor mesophase spheres were observed. The thin-sectioned AOI contain the same phases, in the same amount. However they are devoided of surrounding droplets, i.e. AOI or α resins are made of carbon blacks and radial or alternate spheres, in the AOI observed after grinding only the carbon blacks particles remain, this means that radial or alternate spheres are viscoelastic or plastic.

Dehumidification of Turbulent Air Flow over a Thick Fin: An Experimental Study

An experimental study has been carried out to investigate the performance of a vertical rectangular fin of finite thickness and moderate size when dehumidification occurs in turbulent flow. Tests were conducted for various free-stream velocities and relative humidities for a blunt leading edged fin under both dry and wet conditions. Further tests were also devised for an attached elliptical leading edge. Lower dry and wet fin surface temperatures were recorded for an elliptical leading edge due to the absence of flow separation and reattachment. During dehumidification tests, water droplets of various sizes formed on the surface of the fin. On the basis of visual observation, for a clean surface, no film condensation occurred. Using the theoretical model reported in reference (1) and the measured fin surface temperatures, heat-transfer correlations in terms of Nusselt and Reynolds numbers were developed. These correlations allowed the effect of simultaneous heat and mass transfer to be estimated. Dry and wet fin efficiencies were also determined for both blunt and elliptical leading edges using the measured fin surface temperatures.

Chemical consequences of the initial diffusional growth of cloud droplets: a clean marine case

A simple microphysical cloud parcel model and a simple representation of the background marine aerosol are used to predict the concentrations and compositions of droplets of various sizes near cloud base. The aerosol consists of an externally-mixed ammonium bisulfate accumulation mode and a sea-salt coarse particle mode. The difference in diffusional growth rates between the small and large droplets as well as the differences in composition between the two aerosol modes result in substantial differences in solute concentration and composition with size of droplets in the parcel. The chemistry of individual droplets is not, in general, representative of the “bulk” (volume-weighted mean) cloud water sample. These differences, calculated to occur early in the parcel's lifetime, should have important consequences for chemical reactions such as aqueous phase sulfate production. DOI: 10.1111/j.1600-0889.1989.tb00124.x

Droplet vaporization in supercritical pressure environments

For most liquid-fueled combustion systems the behavior of the fuel as it is introduced to the combustion zone, often by spray injection, will have a significant impact on combustion. The subsequent combustion may be affected to a considerable degree by the initial spread of the liquid, break-up of larger fuel sheets and droplets into droplets of various sizes, droplet vaporization, and diffusion of gaseous fuel. Among the many factors which affect spray break-up and droplet vaporization are the environmental conditions into which the spray is introduced. For both diesel engines and rockets the environment pressure and temperature may be above the critical pressure and temperature of the injected fuel. In a compression-ignition internal combustion engine, the environment consists primarily of air, at pressures from 20 to 100 atmospheres and temperatures ranging from 900 to 1500 K. Even higher pressures are encountered in turbocharged diesels. A typical diesel reference fuel, dodecane, has a thermodynamic critical pressure of about 17 atmospheres, and a critical temperature of 600 K. Fuel is injected into a diesel engine environment in which ambient pressures exceed the critical pressure. While droplet temperatures are subcritical at first, they may rise to the critical temperature or higher. This paper will survey current understanding of supercritical pressure droplet vaporization. Specifically, the topics covered will include: liquid phase behavior; vapor phase behavior; thermodynamic and transport properties; droplet distribution and break-up; micro-explosions; and effects of microgravity.

Relationship between Critical Supersaturation and Cloud Droplet Size: Implications for Cloud Mixing Processes

Abstract Cloud condensation nuclei (CCN) measurements within stratus clouds that have involved droplet separation have revealed a clear preference for droplet activation on the nuclei with the lowest critical supersaturations (Sc). When droplets of various sizes were separated from a sample, a consistent relationship between cloud droplet size and nucleus Sc was discovered—large droplets tend to grow on large (low Sc) nuclei and vice versa. Interpretation in terms of various modes of mixing between clouds and the dry environment demonstrates a preference for the homogeneous mixing process.

TRANSIENT MASS AND HEAT TRANSFER FROM A CLOUD OF VAPORIZING DROPLETS OF VARIOUS SIZE DISTRIBUTIONS: A SECTIONAL APPROACH

A population of vaporizing liquid droplets of a wide range of sizes suspended in a stagnant heated atmosphere is considered. Interaction between neighboring droplets is taken into account through the ‘cooling effect’ due to latent heat absorption. To avoid the dimensionality problem associated with the discrete form of droplet population balance equations, “sectional-conservation-equations” are used. Since droplets of various sizes differ in their vaporization rates, “sectional-vaporization-coefficients” are presented. New solutions for the coupled energy and sectional size distribution equations arc presented and the transient changes in droplet size distribution are analyzed. The analysis takes into account the density of the spray, the distribution of interfacial area between the phases, rates of droplet vaporization, and the properties of the surrounding vapor-gas mixture. All the above-mentioned properties of the spray and surrounding gas are combined here to form a new nondimensional group-vaporizat...

Fat distribution in the skin of bottlenose dolphins (Tursiops truncatus and Tursiops gilli).

Frozen sections stained with Oil-red-O and semithin (0.5 μm) plastic sections stained with toluidine blue revealed an abundance of fat globules of various sizes in all strata of the epidermis of bottlenose dolphins (Tursiops truncatus and T. gilli). The fat was rather evenly distributed but sometimes appeared as circumscribed areas of heavier concentration involving hundreds of cells (as seen in a single plane). Occasionally, there were smaller groups of epidermal cells heavily loaded with lipid. The dermis presented a unique phenomenon in the presence of abundant extracellular fat distributed among the collagen bundles as droplets of various sizes or as larger, irregularly shaped lipid particles that seemed to conform to the spaces between collagen bundles. These lipid particles were sometimes seen to be closely applied to the dermal surface of the stratum basale. Equally unusual was the presence of lipid particles of various sizes and shapes in the lumen of some of the vessels of the dermal papillae. Granular cells resembling mast cells were commonly seen in the papillary dermis and some were closely associated with lipid particles. Blood vessels of the reticular dermis tended to have collections of lipid droplets in the loose connective tissue often found adjacent to the tunica adventitia. It is postulated that the extracellular dermal lipids (probably mainly triglycerides) are broken down to free fatty acids that diffuse into the basal layer of the epidermis and are there resynthesized into triglycerides. Possible uses for the epidermal lipids are discussed.

Osmophores of Scaphosepalum (Orchidaceae)

Scaphosepalum Pfitz. (Orchidaceae) contains ca. 25 Neotropical species occurring epiphytically in montane cloud forests. Osmophores of the nonresupinate flowers occur as glandular pads on adaxial surfaces of lateral sepal apices, the dorsal sepal apex, or all three, depending on the species. Dorsal sepals may be fleshy, terete, and function as osmophores along their distal portions. In all species, only the epithelium and/or a few underlying layers have dense cytoplasm with large nuclei, numerous mitochondria, and unusually abundant cisternae of endoplasmic reticulum. Cells of other layers are highly vacuolate, or plastids may contain starch grains. Osmiophilic, lipophilic droplets of various sizes occur in many cells of both epidermal surfaces. On the basis of osmophore position and floral morphology, it is possible to speculate on the pollination process itself, which is as yet unknown for this genus.

Studies on the ontogeny and ultrastructure of the sclerotium of Botrytis cinerea Pers. ex Nocca & Balbis

The ontogeny and ultrastructure of sclerotia of the fungus Botrytis cinerea Pers. ex Nocca & Balbis were studied by light, scanning, and transmission electron microscopy. Exudation droplets of various sizes and colour accumulated on sclerotial surfaces during development and eventually disappeared. A surface hyphal weft was present over sclerotia at maturity, forming a dense covering which often obscured the underlying rind. The rind consisted of highly vacuolated cells with thick, pigmented walls that remained intact even in old sclerotia. The cortex was poorly defined and usually consisted of only one layer of cells. The prosenchymatous medulla constituted the main volume of mature sclerotia. The ultrastructure of young sclerotial hyphae was similar to that of actively growing vegetative hyphae. Hyphae of mature sclerotia contained fewer nuclei and profiles of mitochondria and endoplasmic reticulum than young sclerotial hyphae. Electron-dense structures, tentatively identified as protein and polyphosphate bodies, were observed in hyphae of the cortex and medulla. Sclerotia of B. cinerea were structurally similar to those of Sclerotinia spp.

Pathogenesis of Fatty Liver in Rats Fed A High Protein Diet Without Pyridoxine

Fatty liver induced in rats by a high protein diet without pyridoxine was studied morphologically. The microscopic change was characterized by accumulation of fat in hepatocytes of the centrolobular and midzonal areas. Electron microscopic examination at an early stage showed marked accumulation of small osmiophilic particles in the granular endoplasmic reticulum and vesicles throughout the cytoplasm with similar particles in the spaces of Disse. After 4 weeks, numerous lipid droplets of various sizes were seen in pericanalicular lysosomes in hepatocytes with concomitant increase in the triglyceride level. The droplets gradually formed larger droplets in the cytoplasm. After 8 weeks, myelin figures together with fat droplets were seen in continuity with the endoplasmic reticulum and occasionally crystal clefts were observed within lysosomes of hepatocytes. These findings suggest that development of fatty liver results from impaired lysosomal degradation of lipid.pyridoxine deficiency fatty liver myelin figure lysosome

Fine structural changes in the liver of young and old rats as influenced by microsomal enzyme inducers.

When given orally to young and old rats, pregnenolone-16 alpha-carbonitrile, spironolactone, or phenobarbital, known microsomal enzyme inducers, caused an increase in smooth endoplasmic reticulum. Dexamethasone, while a potent microsomal enzyme inducer, did not cause smooth endoplasmic reticulum increase. In both untreated and treated old rats, there was dilatation and vesiculation of rough endoplasmic reticulum with occasional granular material present in vesicles. Cytoplasmic lipid droplets of various sizes were frequent. Some mitochondria exhibited polymorphism and a variation in matrical density. Lysosomes and autophagic vacuoles as well as lipid droplets of various sizes were frequent in all groups. These results show that microsomal enzyme inducers influence the subcellular structure of hepatocytes in old rats.

セボレヤ症状ラットの肝臓および皮膚に関する組織学的観察

1. Degenerative changes occurred in the liver of rats administered with sperm oil, and the hepatic cells of the central part showed atrophy and necrosis. The blood corpuscles in capillaries around the hepatic central vein increased in number, indicating the symptoms of an early stage of congestive liver.2. In the rats with seborrhea induced by cotton seed oil, the symptoms of fatty liver were observed and numerous lipid droplets of various sizes were detected in the cytoplasm of hepatic cells around Glisson's sheath.3. The sebaceous glands were markedly hypertrophied and functionally stimulated. The lipid granules in the cells of these glands increased in size and number.