Membrane
hideA membrane is a layer of material which serves as a selective barrier between two phases and remains impermeable to specific particles, molecules, or substances when exposed to the action of a driving force. Some components are allowed passage by the membrane into a permeate stream, whereas others are retained by it and accumulate in the retentate stream.
Membranes can be of various thickness, with homogeneous or heterogeneous structure. Membrane can also be classified according to their pore diameter. According to IUPAC, there are three different types of pore size classifications: microporous (dp < 2nm), mesoporous (2nm < dp < 50nm) and macroporous (dp > 50nm). Membranes can be neutral or charged, and particles transport can be active or passive. The latter can be facilitated by pressure, concentration, chemical or electrical gradients of the membrane process. Membranes can be generally classified into three groups: inorganic, polymeric or biological membranes. These three types of membranes differ significantly in their structure and functionality.
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News tagged with membrane
Computational microscope peers into the working ribosome (w/ Video)
Nov 23, 2009 |
4.9 / 5 (9) |
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Two new studies reveal in unprecedented detail how the ribosome interacts with other molecules to assemble new proteins and guide them toward their destination in biological cells. The studies used molecular ...
Tiny injector to speed development of new, safer, cheaper drugs
Chemistry / Analytical Chemistry
Nov 04, 2009 |
4.8 / 5 (4) |
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It's no bigger than a stamp packet but it has the potential to allow rapid development of a new generation of drugs and genetic engineering organisms, and to better control in-vitro fertilization.
Chromosomes dance and pair up on the nuclear membrane (w/ Video)
Nov 13, 2009 |
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(PhysOrg.com) -- Meiosis - the pairing and recombination of chromosomes, followed by segregation of half to each egg or sperm cell - is a major crossroads in all organisms reproducing sexually. Yet, how the ...
Imaging study shows HIV particles assembling around its genome
Medicine & Health / HIV & AIDS
Nov 17, 2009 |
5 / 5 (1) |
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(PhysOrg.com) -- The genesis of one the planet's most lethal viruses, HIV, has been caught on tape. New imaging experiments show individual HIV genomes -- strands of RNA — docking on the inner membrane of an infected cell ...
Laser surgery does not appear to have long-term effects on corneal cells
Nov 09, 2009 |
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Laser eye surgery to correct vision problems does not appear to be associated with lasting changes to cells lining the inside of the cornea at nine years after the procedure, according to a report in the November issue of ...
An atomic-level look at an HIV accomplice
Nov 19, 2009 |
1 / 5 (1) |
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(PhysOrg.com) -- Since the discovery in 2007 that a component of human semen called SEVI boosts infectivity of the virus that causes AIDS, researchers have been trying to learn more about SEVI and how it works, in hopes of ...
Control of blood clotting by platelets described; provides medical promise
Nov 24, 2009 |
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Cell fragments called platelets are essential to promote blood clotting. Virginia Tech faculty members and students have discovered novel molecular interactions at the surface of platelets that control blood clotting.
Early protein processes crucial to formation and layering of myelin membrane
Nov 24, 2009 |
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New findings from an international team of researchers probing the nerve-insulating myelin sheath were bolstered by the work of Boston College biologists, who used x-rays to uncover how mutations affect the structure of myelin, ...
