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Membrane
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 mucous membrane, mucosae and serous membrane, serosae. Synthetic membranes are made by humans for use in laboratory, 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, membran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic mole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Bioreactor
Membrane bioreactors are combinations of membrane processes like microfiltration or ultrafiltration with a biological wastewater treatment process, the activated sludge process. These technologies are now widely used for municipal and industrial wastewater treatment.S. Judd, The MBR book (2006) Principles and applications of membrane bioreactors in water and wastewater treatment, Elsevier, Oxford The two basic membrane bioreactor configurations are the submerged membrane bioreactor and the side stream membrane bioreactor. In the submerged configuration, the membrane is located inside the biological reactor and submerged in the wastewater, while in a side stream membrane bioreactor, the membrane is located outside the reactor as an additional step after biological treatment. Overview Water scarcity has prompted efforts to reuse waste water once it has been properly treated, known as " water reclamation" (also called wastewater reuse, water reuse, or water recycling). Among the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Membrane
A biological membrane, biomembrane or cell membrane is a selectively permeable membrane that separates the interior of a cell from the external environment or creates intracellular compartments by serving as a boundary between one part of the cell and another. Biological membranes, in the form of eukaryotic cell membranes, consist of a phospholipid bilayer with embedded, integral and peripheral proteins used in communication and transportation of chemicals and ions. The bulk of lipids in a cell membrane provides a fluid matrix for proteins to rotate and laterally diffuse for physiological functioning. Proteins are adapted to high membrane fluidity environment of the lipid bilayer with the presence of an annular lipid shell, consisting of lipid molecules bound tightly to the surface of integral membrane proteins. The cell membranes are different from the isolating tissues formed by layers of cells, such as mucous membranes, basement membranes, and serous membranes. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Osmosis
Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane, semi-permeable membrane to separate water molecules from other substances. RO applies pressure to overcome osmotic pressure that favors even distributions. RO can remove dissolved or suspended chemical species as well as biological substances (principally bacteria), and is used in industrial processes and the production of potable water. RO retains the solute on the pressurized side of the membrane and the purified solvent passes to the other side. The relative sizes of the various molecules determines what passes through. "Selective" membranes reject large molecules, while accepting smaller molecules (such as solvent molecules, e.g., water). Reverse osmosis is most commonly known for its use in drinking water purification from seawater, removing the salt and other effluent materials from the water molecules. As of 2013 the world's largest RO desalination plant was in Nahal Sorek, So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrafiltration
Ultrafiltration (UF) is a variety of membrane filtration in which forces such as pressure or concentration gradients lead to a separation through a semipermeable membrane. Suspended solids and solutes of high molecular weight are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in the permeate (filtrate). This separation process is used in industry and research for purifying and concentrating macromolecular (103–106 Da) solutions, especially protein solutions. Ultrafiltration is not fundamentally different from microfiltration. Both of these are separate based on size exclusion or particle capture. It is fundamentally different from membrane gas separation, which separate based on different amounts of absorption and different rates of diffusion. Ultrafiltration membranes are defined by the molecular weight cut-off (MWCO) of the membrane used. Ultrafiltration is applied in cross-flow or dead-end mode. Applica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfiltration
Microfiltration is a type of physical filtration process where a contaminated fluid is passed through a special porosity, pore-sized membrane filter to separate microorganisms and suspended particles from process fluid, liquid. It is commonly used in conjunction with various other separation processes such as ultrafiltration and reverse osmosis to provide a product stream which is free of undesired contamination, contaminants. General principles Microfiltration usually serves as a pre-treatment for other separation processes such as ultrafiltration, and a post-treatment for Sand filter, granular media filtration. The typical particle size used for microfiltration ranges from about 0.1 to 10 micrometre, μm.Baker, R 2012, ''Microfiltration, in Membrane Technology and Applications'', 3rd edn, John Wiley & Sons Ltd, California. p. 303 In terms of approximate molecular weight these Synthetic membrane, membranes can separate macromolecules of molecular weights generally less than 100,0 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanofiltration
Nanofiltration is a Membrane technology, membrane filtration process that uses nanometer sized pores through which particles smaller than about 1–10 nanometers pass through the membrane. Nanofiltration membranes have pore sizes of about 1–10 nanometers, smaller than those used in microfiltration and ultrafiltration, but a slightly bigger than those in reverse osmosis. Membranes used are predominantly polymer thin films. It is used to soften, disinfect, and remove impurities from water, and to purify or separate chemicals such as pharmaceuticals. Membranes Membrane materials that are commonly used are polymer thin films such as polyethylene terephthalate or metals such as aluminium. Pore dimensions are controlled by pH, temperature and time during development with pore densities ranging from 1 to 106 pores per cm2. Membranes made from polyethylene terephthalate (PET) and other similar materials, are referred to as "track-etch" membranes, named after the way the pores on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Fouling
Membrane fouling is a process whereby a solution or a particle is deposited on a membrane surface or in membrane pores in a processes such as in a membrane bioreactor, reverse osmosis, forward osmosis, membrane distillation, ultrafiltration, microfiltration, or nanofiltration so that the membrane's performance is degraded. It is a major obstacle to the widespread use of this technology. Membrane fouling can cause severe flux decline and affect the quality of the water produced. Severe fouling may require intense chemical cleaning or membrane replacement. This increases the operating costs of a treatment plant. There are various types of foulants: colloidal (clays, flocs), biological (bacteria, fungi), organic (oils, polyelectrolytes, humics) and scaling (mineral precipitates). Fouling can be divided into reversible and irreversible fouling based on the attachment strength of particles to the membrane surface. Reversible fouling can be removed by a strong shear force or backwashi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Membrane
The nuclear envelope, also known as the nuclear membrane, is made up of two lipid bilayer polar membrane, membranes that in eukaryotic cells surround the Cell nucleus, nucleus, which encloses the genome, genetic material. The nuclear envelope consists of two lipid bilayer membranes: an inner nuclear membrane and an outer nuclear membrane. The space between the membranes is called the perinuclear space. It is usually about 10–50 Nanometre, nm wide. The outer nuclear membrane is continuous with the endoplasmic reticulum membrane. The nuclear envelope has many nuclear pores that allow materials to move between the cytosol and the nucleus. Intermediate filament proteins called lamins form a structure called the nuclear lamina on the inner aspect of the inner nuclear membrane and give structural support to the nucleus. Structure The nuclear envelope is made up of two lipid bilayer membranes, an inner nuclear membrane and an outer nuclear membrane. These membranes are connected t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanotube Membrane
Nanotube membranes are either a single, open-ended nanotube (CNT) or a film composed of an array of nanotubes that are oriented perpendicularly to the surface of an impermeable film matrix like the cells of a honeycomb. 'Impermeable' is essential here to distinguish nanotube membrane with traditional, well known porous membranes. Fluids and gas molecules may pass through the membrane en masse but only through the nanotubes. For instance, water molecules form ordered hydrogen bonds that act like chains as they pass through the CNTs. This results in an almost frictionless or atomically smooth interface between the nanotubes and water which relate to a "slip length" of the hydrophobic interface. Properties like the slip length that describe the non-continuum behavior of the water within the pore walls are disregarded in simple hydrodynamic systems and absent from the Hagen–Poiseuille equation. Molecular dynamic simulations better characterize the flow of water molecules through the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Transport
In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport, which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area of low concentration, with energy. Active transport is essential for various physiological processes, such as nutrient uptake, hormone secretion, and nig impulse transmission. For example, the sodium-potassium pump uses ATP to pump sodium ions out of the cell and potassium ions into the cell, maintaining a concentration gradient essential for cellular function. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hollow Fiber Membrane
Hollow fiber membranes (HFMs) are a class of synthetic membrane, artificial membranes containing a Membrane, semi-permeable barrier in the form of a hollow fiber. Originally developed in the 1960s for reverse osmosis applications, hollow fiber membranes have since become prevalent in water treatment, desalination, cell culture, medicine, and tissue engineering. Most commercial hollow fiber membranes are packed into cartridges which can be used for a variety of liquid and gaseous separations. Manufacturing HFMs are commonly produced using list of synthetic polymers, artificial polymers. The specific production methods involved are heavily dependent on the type of polymer used as well as its molecular weight. HFM production, commonly referred to as "spinning", can be divided into four general types: * Melt Spinning, in which a thermoplastic polymer is melted and extruded through a Spinneret (polymers), spinneret into air and subsequently cooled. * Dry Spinning, in which a poly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
