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
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.
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 ...
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, ...
Major insights into evolution of life reported
Aug 19, 2009 |
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(PhysOrg.com) -- Humans might not be walking the face of the Earth were it not for the ancient fusing of two prokaryotes -- tiny life forms that do not have a cellular nucleus. UCLA molecular biologist James ...
Chemists discover recipe to design a better type of fuel cell
Oct 18, 2009 |
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Fuel cells are often touted as one method to help decrease society's addiction to fossil fuels. But there is still a lot of work to be done before fuel cells will be ready for mass market to be used in transportation, home ...
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 ...
Robo-bats with metal muscles may be next generation of remote control flyers
Jul 07, 2009 |
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Tiny flying machines can be used for everything from indoor surveillance to exploring collapsed buildings, but simply making smaller versions of planes and helicopters doesn't work very well. Instead, researchers ...
Implantable Device Offers Continuous Cancer Monitoring
Nanotechnology / Bio & Medicine
Jul 21, 2009 |
5 / 5 (3) |
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(PhysOrg.com) -- Surgical removal of a tissue sample is now the standard for diagnosing cancer. Such procedures, known as biopsies, are accurate but offer only a snapshot of the tumor at a single moment in time.
Breakthrough uses light to manipulate cell movement
Aug 19, 2009 |
5 / 5 (6) |
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One of the biggest challenges in scientists' quest to develop new and better treatments for cancer is gaining a better understanding of how and why cancer spreads. Recent breakthroughs have uncovered how ...
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 ...
Scientists manipulate ripples in graphene, enabling strain-based graphene electronics (w/ Video)
Nanotechnology / Nanomaterials
Jul 26, 2009 |
4.8 / 5 (13) |
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(PhysOrg.com) -- Graphene is nature's thinnest elastic material and displays exceptional mechanical and electronic properties. Its one-atom thickness, planar geometry, high current-carrying capacity and thermal ...
Researchers identify new, cancer-causing role for protein
Aug 27, 2009 |
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The mainstay immune system protein TRAF6 plays an unexpected, key role activating a cell signaling molecule that in mutant form is associated with cancer growth, researchers at The University of Texas M. D. ...
