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Collodion Bag
A collodion bag is a membrane used to filter or concentrate substances, often proteins, using pressure. It usually takes the form of a small finger shaped receptacle hooked up to a positive pressure pump. The bag has a characteristic pore size that allows small particles, like water or unbound ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...s, to flow out while retaining larger particles in the bag. References Further readingModern Techniques in Cytopathology [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane (selective Barrier)
A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. Biological membranes include cell membranes (outer coverings of cells or organelles that allow passage of certain constituents); nuclear membranes, which cover a cell nucleus; and tissue membranes, such as mucosae and serosae. Synthetic membranes are made by humans for use in laboratories and industry (such as chemical plants). This concept of a membrane has been known since the eighteenth century but was used little outside of the laboratory until the end of World War II. Drinking water supplies in Europe had been compromised by the war and membrane filters were used to test for water safety. However, due to the lack of reliability, slow operation, reduced selectivity and elevated costs, membranes were not widely exploited. The first use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive Pressure
Positive pressure is a pressure within a system that is greater than the environment that surrounds that system. Consequently, if there is any leak from the positively pressured system it will egress into the surrounding environment. This is in contrast to a negative pressure room, where air is sucked in. Use is also made of positive pressure to ensure there is no ingress of the environment into a supposed closed system. A typical example of the use of positive pressure is the location of a habitat in an area where there may exist flammable gases such as found on an oil platform or laboratory cleanroom. This kind of positive pressure is also used in operating theaters and ''in vitro'' fertilisation (IVF) labs. Hospitals may have positive pressure rooms for patients with compromised immune systems. Air will flow out of the room instead of in, so that any airborne microorganisms (e.g., bacteria) that may infect the patient are kept away. This process is important in human and c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pore Size
Pore may refer to: Biology Animal biology and microbiology * Sweat pore, an anatomical structure of the skin of humans (and other mammals) used for secretion of sweat * Hair follicle, an anatomical structure of the skin of humans (and other mammals) used for secretion of sebum * Canal pore, an anatomical structure that is part of the lateral line sense system of some aquatic organisms * Gonopore, a genital pore present in some invertebrates, particularly insects * Ozopore, the external discharge site of defensive glands in millipedes and some arachnids * An opening across both inner and outer bacterial membranes, a part of many Gram-negative bacterial secretion systems * One of the openings communicating with the skin surface at the terminus of lactiferous ducts in milk-producing mammals Plant and fungal biology * Germ pore, a small pore in the outer wall of a fungal spore through which the germ tube exits upon germination * Stoma, a small opening on a plant leaf used for g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
