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
Chemical energy influences tiny vibrations of red blood cell membranes
Dec 21, 2009 |
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(PhysOrg.com) -- Much like a tightly wound drum, red blood cells are in perpetual vibration. Those vibrations help the cells maintain their characteristic flattened oval or disc shape, which is critical to ...
Researchers create new 'smart' nanocapsule delivery system for use in protein therapy
Nanotechnology / Bio & Medicine
Dec 18, 2009 |
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the delivery of healthy proteins directly into human cells to replace malfunctioning proteins — is considered one of the most direct and safe approaches for treating diseases. But its effectiveness has been limited by low ...
Synthetic protein mimics structure, function of metalloprotein in nature
Dec 10, 2009 |
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Scientists have designed a synthetic protein that is both a structural model and a functional model of a native protein, nitric-oxide reductase.
A cell's 'cap' of bundled fibers could yield clues to disease (w/ Video)
Dec 02, 2009 |
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It turns out that wearing a cap is good for you, at least if you are a mammal cell.
Nervy research: Researchers take initial look at ion channels in a model system
Dec 02, 2009 |
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Before one of your muscles can twitch, before the thought telling it to flex can race down your nerve, a tiny floodgate of sorts -- called an ion channel -- must open in the surface of each cell in these organs ...
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, ...
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.
Computational microscope peers into the working ribosome (w/ Video)
Nov 23, 2009 |
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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 ...
An atomic-level look at an HIV accomplice
Nov 19, 2009 |
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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 ...
Imaging study shows HIV particles assembling around its genome
Medicine & Health / HIV & AIDS
Nov 17, 2009 |
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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 ...
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 ...
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 ...
Tiny injector to speed development of new, safer, cheaper drugs
Chemistry / Analytical Chemistry
Nov 04, 2009 |
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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.
Gold Nanoparticles Delivery Platinum Warheads to Tumors
Nanotechnology / Bio & Medicine
Oct 29, 2009 |
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(PhysOrg.com) -- Cisplatin is one of the most powerful and effective drugs for treating a wide variety of cancers, but serious side effects ultimately limit the drug's use and effectiveness. Now, however, researchers have ...
HIV tamed by designer 'leash'
Medicine & Health / HIV & AIDS
Oct 29, 2009 |
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Researchers have shown how an antiviral protein produced by the immune system, dubbed tetherin, tames HIV and other viruses by literally putting them on a leash, to prevent their escape from infected cells. The insights reported ...
