Mathematical Model of the Deaeration of Finely Dispersed Solid Media in a Spherical Matrix of a Roller-Type Apparatus

The additional operation of deaeration (compaction) of powders affects the quality of many products of chemical industries, the conditions for their delivery. Otherwise, energy consumption increases significantly. The aim of this work is the modeling of the deaeration of solid finely dispersed media in a gap with perforated hemispherical shapes on the surfaces of the shaft and conveyor belt within the framework of the mechanics of heterogeneous systems. A plane-deformation model is described, neglecting the forces of interphase interaction and taking into account the compressibility of a solid-particle-gas mixture without elastoplastic deformations. The model assumes consideration of the movement of (1) the components of the solid skeleton together with the carrying phase as a whole; (2) gas in an isothermal state through the pores of a finely dispersed material. This work is devoted to the study of part (a), i.e., behavior of the solid particle-gas system as a whole. The efficiency of the seal-deaerator is estimated using the obtained analytical dependencies for the main strength and speed indicators. The change in the degree of compaction of a spherical granule made of kaolin with given strength characteristics is investigated. It is shown that for the initial time interval up to 3.7⨯10−2 s, the growth of the porosity value relative to the horizontal coordinate along the conveyor belt is exponential and increases by a factor of 1.1. After eight such time intervals, the porosity values stabilize along the indicated coordinate with an increase of more than 1.4 times from the initial value.

Visualization of Regulated Exocytosis with a Granule-Membrane Probe Using Total Internal Reflection Microscopy

Secretory granules labeled with Vamp-green fluorescent protein (GFP) showed distinct signatures upon exocytosis when viewed by total internal reflection fluorescence microscopy. In ∼90% of fusion events, we observed a large increase in fluorescence intensity coupled with a transition from a small punctate appearance to a larger, spreading cloud with free diffusion of the Vamp-GFP into the plasma membrane. Quantitation suggests that these events reflect the progression of an initially fused and spherical granule flattening into the plane of the plasma membrane as the Vamp-GFP simultaneously diffuses through the fusion junction. Approximately 10% of the events showed a transition from puncta to ring-like structures coupled with little or no spreading. The ring-like images correspond quantitatively to granules fusing and retaining concavity (recess of ∼200 nm). A majority of fusion events involved granules that were present in the evanescent field for at least 12 s. However, ∼20% of the events involved granules that were present in the evanescent field for no more than 0.3 s, indicating that the interaction of the granule with the plasma membrane that leads to exocytosis can occur within that time. In addition, ∼10% of the exocytotic sites were much more likely to occur within a granule diameter of a previous event than can be accounted for by chance, suggestive of sequential (piggy-back) exocytosis that has been observed in other cells. Overall granule behavior before and during fusion is strikingly similar to exocytosis previously described in the constitutive secretory pathway.

CYTOPLASMIC FINE STRUCTURE OF SCIARA SALIVARY GLANDS

Cells from the anterior segment of the salivary glands of Sciara coprophila were found to synthesize and secrete into the gland lumen three morphologically distinct types of granule: 1) A large, electron-lucid granule, up to 1 µ in diameter, staining only faintly with pH 2 fast green and the PAS reaction; 2) an ellipsoid granule of moderate density, strongly fast green and PAS positive; and 3) a small spherical granule of high electron density. The cells contained numerous Golgi areas, up to an estimated 8,000 per cell. Evidence is presented for the transfer of material from the endoplasmic reticulum to the Golgi areas via small vesicles. Three types of Golgi areas were distinguishable, each containing intercisternal material resembling one of the three types of secretion granule. Patterns of secretion granule synthesis varied with the developmental stage of the larva as determined by counts of eye spots in the eye anlage. Lucid granules were most abundant in the youngest larvae, and decreased in abundance as larvae grew older, becoming virtually absent in prepupae. The small, dense granules were present in all gland cells, but became more prevalent in older larvae and prepupae. Ellipsoid granules were only occasionally present, and were independent of larval stage. It is suggested that lucid granules are digestive in function, since their abundance correlates with feeding patterns. Other granules may produce the external slime coating of the larvae, and also the mucoprotein component of the pupal cocoon.

THE MORPHOLOGY OF A SPECIES OF THE BACTERIAL GENUS CYTOPHAGA WINOG. IN CULTURE

A culture of the cellulolytic bacterial organism, Sporocytophaga myxococcoides (A.T.C.C. No. 10010), has been studied. In or on media containing cellulose, the primary effective cells are long and acuminate; in old cultures a large proportion of them become spherical or spheroid and are bound together in mucilage, in which new spheroid cells develop. In or on media containing cellobiose, glucose, or mannose as the source of carbon, the primary effective cells resemble those on cellulose media, but the resting cell is a spherical granule, its diameter not more than twice the width of the acuminate cell; the spheroid cells do not become aggregated in the mucilage, and do not physically resemble the so-called microcysts except in shape.