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A phototube or photoelectric cell is a type of gas-filled or vacuum tube that is sensitive to light. Such a tube is more correctly called a 'photoemissive cell' to distinguish it from photovoltaic or photoconductive cells. Phototubes were previously more widely used but are now replaced in many applications by solid state photodetectors.
Schwann dedicated a chapter of the treatise to explicitly formulate the cell theory, stating that ("the elementary parts of all tissues are formed of cells” and that “there is one universal principle of development for the elementary parts of organisms... and this principle is in the formation of cells" (Henry Smith's translation, 1847).
In chemical engineering, a Stefan tube is a device that was devised by Josef Stefan in 1874. [1] It is often used for measuring diffusion coefficients . [ 1 ] [ 2 ] It comprises a vertical tube, over the top of which a gas flows and at the bottom of which is a pool of volatile liquid that is maintained in a constant-temperature bath.
In shell-and-tube heat exchangers there is a potential for a tube to rupture and for high pressure (HP) fluid to enter and over-pressurise the low pressure (LP) side of the heat exchanger. [8] The usual configuration of exchangers is for the HP fluid to be in the tubes and for LP water, cooling or heating media to be on the shell side.
is the angle of the tube with respect to the horizontal axis. ϕ {\displaystyle \phi } is the contact angle of the liquid on the capillary material. Substituting these expressions leads to the first-order differential equation for the distance the fluid penetrates into the tube l {\displaystyle l} :
In fluid dynamics, the Knudsen equation is used to describe how gas flows through a tube in free molecular flow. When the mean free path of the molecules in the gas is larger than or equal to the diameter of the tube, the molecules will interact more often with the walls of the tube than with each other. For typical tube dimensions, this occurs ...
From these conclusions about plants and animals, two of the three tenets of cell theory were postulated. 1. All living organisms are composed of one or more cells 2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert ...
A type of low power triode for use at ultrahigh frequencies (UHF), the "lighthouse" tube, has a planar construction to reduce interelectrode capacitance and lead inductance, which gives it the appearance of a "lighthouse". The disk-shaped cathode, grid and plate form planes up the center of the tube - a little like a sandwich with spaces ...