Acoustic Tunnelling of Internal Gravity waves in the stratified fluids

This paper focuses on the study of acoustic propagation of internal gravity waves which generates small scale variations through propagation and hence can obtain transmission co-efficients using N2 buoyancy frequency variation of a compressible stratified fluid for a small regions. We have also analysed the results using the asymptotic expansions for large compressible limits. The reduction of the transmission in the N2-barrier region for the density layers sandwiched along with acoustic waves is obtained through graphs for different density barrier regions. The dispersion characteristics shows the contours of the transmission in the wave number plane. The curves for ! < N0 are hyperbolic, representing internal gravity waves as these become the dispersionwaves for an incompressible fluid and the curve with ! > N0 are ellipsoids which represent the acoustic gravity or infrasonic waves for the cut off frequency

Purification of Gastric Mucosal ECL Cells from a Crude Elutriation Fraction

Acid-secreting parietal cells from the gastric mucosa are widely studied as a model in studies on ion transport and the endocrine/paracrine ECL cells effectively control parietal cell function. Discontinuous gradients of iodixanol for the purification of ECL cells were subsequently simplified to the use of a density barrier. This technique is now commonly used following initial centrifugal elutriation.

Isolation of Peripheral Blood Mononuclear Cells from Macaques on a Density Barrier

The standard techniques for the isolation of human peripheral blood mononuclear cells (PBMCs) using commercial “lymphocyte isolation media” cannot be satisfactorily extended to experimental animals without manipulating either the density or the osmolality of the medium. PBMCs from Macaques can also be isolated from whole blood by sedimentation on to a density barrier containing approx. 10% iodixanol, polysucrose (Ficoll) with a density of approx 1.074 g/ml.

Separation of Monocytes from Whole Human Blood

Human peripheral blood monocytes are isolated by flotation from whole blood through a single low-density barrier prepared from OptiPrep™ at 4°C. The separation from lymphocytes depends on the more rapid rate of flotation of the monocytes because of their slightly lower density and larger size. The method works optimally only with fresh (within 2 h of drawing) EDTA-anticoagulated blood. Preliminary evidence suggests that this technique may be applicable to blood from rats.

Isolation of Human Platelets (Thrombocytes)

Platelets from human blood can be isolated in high yield by centrifugation of whole blood over an iodixanol density barrier of 1.063 g/ml. The separation from all of the blood cells (which form a pellet) is based on the slower sedimentation velocity of the smaller platelets.

Isolation of a Mouse Motoneuron-Enriched Fraction from Mouse Spinal Cord on a Density Barrier

After a combined enzymic and mechanical disruption of the spinal cord tissue, the low-density motoneurons band at the interface of a 1.06-g/ml barrier through which other contaminating cells sediment.