Cellular size

Fluorescence excitation spectroscopy is thus a powerful technique for obtaining molecular information about systems of cellular size. At present, the technique is restricted to single small objects because of the requirement of angular integration of the emitted fluorescence. As work progresses, similiar information will be obtainable from spectra taken at a particular angle with respect to the exciting beam. This will allow extension of the photoselection concept to suspensions of particles and perhaps to individual cells. 

Morphological changes of lymphoid organs and tissues including bone marrow (e.g., altered cellularity/size of major compartments)... 

It is worth reviewing the forces that act and can be used for the manipulation of cells in microstructures. Random thermal (Brownian) motion becomes important for objects of cellular size and very important for smaller ones. The energy associated with this (about 2 x 10 21 J/particle, regardless of size at room temperature) provides a yardstick to which the strengths of the other forces can be compared. For instance, a perfectly controlled force of 10 15 N would be capable of holding a particle within about 2 pm of a target position. 

It is worth remembering that the breaking of chemical bonds requires displacements of only a small fraction of a nanometer. The energies associated with even the strongest of these physical forces acting on an object of cellular size with displacements of this order are only comparable to the energy stored in a very small number of chemical bonds. 

The somatic cell cycle as a double, cdc2-cdk2 oscillator The cell cycle in yeast and in somatic cells appears to be more complex than in embryonic cells as it is subjected to additional controls linking, for example, the onset of mitosis to the successful completion of DNA replication or to the reaching of a critical cellular size (Cross et al, 1989 ... 

Hypertrophy is an increase in cellular size. In contrast hyperplasia is an increase in the number of cells. Sometimes the two can be found together. 

In addition to graft copolymer attached to the mbber particle surface, the formation of styrene—acrylonitrile copolymer occluded within the mbber particle may occur. The mechanism and extent of occluded polymer formation depends on the manufacturing process. The factors affecting occlusion formation in bulk (77) and emulsion processes (78) have been described. The use of block copolymers of styrene and butadiene in bulk systems can control particle size and give rise to unusual particle morphologies (eg, coil, rod, capsule, cellular) (77). 

Typically, dry potassium nitrate is pulverized in a ball mill. Sulfur is milled into cellular charcoal to form a uniform mix in a separate ball mill. The nitrate and the sulfur—charcoal mix are screened and then loosely mixed by hand or in a tumbling machine. Magnetic separators may be used to ensure the absence of ferrous metals. The preliminary mix is transferred to an edge-mimer wheel mill with large, heavy cast iron wheels. A clearance between the pan and the wheels is required for safety purposes. The size of this gap also contributes to the density of the black powder granules obtained. Water is added to minimize dusting and improve incorporation of the nitrate into the charcoal. The milling operation requires ca 3 to 6 h. 

Cell Structure. A complete knowledge of the cell stmcture of a cellular polymer requires a definition of its cell sizes, cell shapes, and location of each cell in the foam. 

Density and polymer composition have a large effect on compressive strength and modulus (Fig. 3). The dependence of compressive properties on cell size has been discussed (22). The cell shape or geometry has also been shown important in determining the compressive properties (22,59,60,153,154). In fact, the foam cell stmcture is controlled in some cases to optimize certain physical properties of rigid cellular polymers. 

Estrogens stimulate cellular proliferation, induce RNA and protein synthesis of uterine endometrium and the fibrous connective tissue framework for ovaries, and increase the size of the cells. This effect leads to the growth and regeneration of the endometrial layer and spinal arterioles, and increase in the number and size of endometrial glands. Under the influence of estrogen, vaginal mucosa becomes thicker, as cervical mucus becomes thinner (85,86). 

A chemical must have certain physicochemical properties to elicit an endocrine disrupting effect. For example, the ability to enter the body and to cross the cell membrane into the cellular medium requires a degree of lipophilicity. Fipophilic potentials may be compared by reference to the chemical s octanol-water coefficient (usually expressed as log K ). This property, together with molecular size and chemical structure, has an important influence on the bioacciimiilation... 

Powdered glass and crushed carbon are placed in molds and heated to 1000°C, at which temperature the carbon is oxidized, forming gas bubbles which causes expansion of the glass mix. The cellular material is then annealed and, after cooling, cut to size. 

The more or less regular pattern of pores imposes a cellular structure on the film, with the cells approximating in plan to hexagons, each with a central pore, while the bases which form the barrier-layer, are rounded. The metal surface underlying the film, therefore, consists of a close-packed regular array of nearly hemispherical depressions which increase in size with the anodising voltage. The thickness of the individual cell walls is approximately equal to that of the barrier-layer... 

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