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69-432: High-resolution images of it in visible and near infrared light reveal a highly symmetric, compact bipolar nebula with X-shaped spikes which imply anisotropic dispersion of the circumstellar material. The central binary system is completely obscured, providing no direct light. The Red Rectangle is known to be particularly rich in polycyclic aromatic hydrocarbons (PAHs). The presence of such carbon-bearing macromolecules in

138-422: A r = G E / [ 2 ( 1 + ν ) ] = 2 ( 1 + ν ) G E ≡ 2 C 44 C 11 − C 12 . {\displaystyle a_{r}={\frac {G}{E/[2(1+\nu )]}}={\frac {2(1+\nu )G}{E}}\equiv {\frac {2C_{44}}{C_{11}-C_{12}}}.} The latter expression

207-409: A Büchner funnel , filter paper of a smaller diameter than the funnel, Büchner flask , and rubber tubing to connect to a vacuum source. Centrifugal filtration is carried out by rapidly rotating the substance to be filtered. The more dense material is separated from the less dense matter by the horizontal rotation. Gravity filtration is the process of pouring the mixture from a higher location to

276-408: A plasma , so that its magnetic field is oriented in a preferred direction. Plasmas may also show "filamentation" (such as that seen in lightning or a plasma globe ) that is directional. An anisotropic liquid has the fluidity of a normal liquid, but has an average structural order relative to each other along the molecular axis, unlike water or chloroform , which contain no structural ordering of

345-470: A bowl holding a porous filter media can be thought of as filters in which a centrifugal force several times stronger than gravity replaces gravitational force. A partial vacuum is typically provided to the container below the filter media when laboratory filtration is challenging to speed up the filtering process. Depending on the type of filter being used, the majority of industrial filtration operations employ pressure or vacuum to speed up filtering and reduce

414-404: A conspicuous bipolar symmetry is usual in protoplanetary and planetary nebulae. Theorists, like Noam Soker , Vincent Icke  [ nl ] , Adam Frank , and others, have shown that this axial symmetry can appear as a result of shocks due to interaction of different phases of the stellar winds (characteristic of the late stellar evolution), but its origin is still debated. On the other hand,

483-548: A difficult quantity to calculate. In remote sensing applications, anisotropy functions can be derived for specific scenes, immensely simplifying the calculation of the net reflectance or (thereby) the net irradiance of a scene. For example, let the BRDF be γ ( Ω i , Ω v ) {\displaystyle \gamma (\Omega _{i},\Omega _{v})} where 'i' denotes incident direction and 'v' denotes viewing direction (as if from

552-548: A high aspect ratio . These features are commonly used in MEMS (microelectromechanical systems) and microfluidic devices, where the anisotropy of the features is needed to impart desired optical, electrical, or physical properties to the device. Anisotropic etching can also refer to certain chemical etchants used to etch a certain material preferentially over certain crystallographic planes (e.g., KOH etching of silicon [100] produces pyramid-like structures) Diffusion tensor imaging

621-406: A liquid, or simply to separate the solid from the liquid. There are many different methods of filtration; all aim to attain the separation of substances. Separation is achieved by some form of interaction between the substance or objects to be removed and the filter. The substance that is to pass through the filter must be a fluid , i.e. a liquid or gas . Methods of filtration vary depending on

690-438: A liquid. Only when a driving force is supplied will the fluid to be filtered be able to flow through the filter media. Gravity , centrifugation, applying pressure to the fluid above the filter, applying a vacuum below the filter, or a combination of these factors may all contribute to this force. In both straightforward laboratory filtrations and massive sand-bed filters, gravitational force alone may be utilized. Centrifuges with

759-483: A lower one. It is frequently accomplished via simple filtration, which involves placing filter paper in a glass funnel with the liquid passing through by gravity while the insoluble solid particles are caught by the filter paper. Filter cones, fluted filters, or filtering pipets can all be employed, depending on the amount of the substance at hand. Gravity filtration is in widespread everyday use, for example for straining cooking water from food, or removing contaminants from

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828-575: A relatively diffuse outflow that is very probably formed of material extracted from the denser disk. The distinct rungs suggest several episodes of increased ejection rate. The Hubble Space Telescope has revealed a wealth of new features in the Red Rectangle that cannot be seen by ground-based telescopes looking through Earth's turbulent atmosphere. The origins of many of the features in this dying star, in particular its X-shaped image, still remain hidden or even outright mysterious. The presence of

897-940: A satellite or other instrument). And let P be the Planar Albedo, which represents the total reflectance from the scene. P ( Ω i ) = ∫ Ω v γ ( Ω i , Ω v ) n ^ ⋅ d Ω ^ v {\displaystyle P(\Omega _{i})=\int _{\Omega _{v}}\gamma (\Omega _{i},\Omega _{v}){\hat {n}}\cdot d{\hat {\Omega }}_{v}} A ( Ω i , Ω v ) = γ ( Ω i , Ω v ) P ( Ω i ) {\displaystyle A(\Omega _{i},\Omega _{v})={\frac {\gamma (\Omega _{i},\Omega _{v})}{P(\Omega _{i})}}} It

966-448: Is a filter with increasingly smaller interstitial spaces in the direction of filtration so that the proximal regions filter out larger particles and distal regions increasingly remove smaller particles, resulting in greater flow-through and more efficient filtration. In fluorescence spectroscopy , the fluorescence anisotropy , calculated from the polarization properties of fluorescence from samples excited with plane-polarized light,

1035-475: Is a method of enhancing the image quality of textures on surfaces that are far away and steeply angled with respect to the point of view. Older techniques, such as bilinear and trilinear filtering , do not take into account the angle a surface is viewed from, which can result in aliasing or blurring of textures. By reducing detail in one direction more than another, these effects can be reduced easily. A chemical anisotropic filter , as used to filter particles,

1104-505: Is a novel technology since natural biofilms are sluggishly developing. The use of biofilms in the biofiltration process allows for the attachment of desirable biomass and critical nutrients to immobilized support. So that water may be reused for various processes, advances in biofiltration methods assist in removing significant volumes of effluents from wastewater . Systems for biologically treating wastewater are crucial for enhancing both human health and water quality . Biofilm technology,

1173-415: Is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the filtrate . Oversize particles may form a filter cake on top of the filter and may also block

1242-438: Is also used as a general term for macrophage in which organisms use a variety of means to filter small food particles from their environment. Examples range from the microscopic Vorticella up to the basking shark , one of the largest fishes, and the baleen whales , all of which are described as filter feeders . Filters may be used for the purpose of removing unwanted liquid from a solid residue, cleaning unwanted solids from

1311-423: Is an MRI technique that involves measuring the fractional anisotropy of the random motion ( Brownian motion ) of water molecules in the brain. Water molecules located in fiber tracts are more likely to move anisotropically, since they are restricted in their movement (they move more in the dimension parallel to the fiber tract rather than in the two dimensions orthogonal to it), whereas water molecules dispersed in

1380-416: Is called a transversely isotropic material . Tensor descriptions of material properties can be used to determine the directional dependence of that property. For a monocrystalline material, anisotropy is associated with the crystal symmetry in the sense that more symmetric crystal types have fewer independent coefficients in the tensor description of a given property. When a material is polycrystalline ,

1449-454: Is composed primarily of silica . Also used are wood cellulose and other inert porous solids such as the cheaper and safer perlite . Activated carbon is often used in industrial applications that require changes in the filtrate's properties, such as altering colour or odour. These filter aids can be used in two different ways. They can be used as a precoat before the slurry is filtered. This will prevent gelatinous-type solids from plugging

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1518-412: Is due to the fact that FDM is designed to extrude and print layers of thermoplastic materials. This creates materials that are strong when tensile stress is applied in parallel to the layers and weak when the material is perpendicular to the layers. Anisotropic etching techniques (such as deep reactive-ion etching ) are used in microfabrication processes to create well defined microscopic features with

1587-576: Is known as the Zener ratio , a r {\displaystyle a_{r}} , where C i j {\displaystyle C_{ij}} refers to elastic constants in Voigt (vector-matrix) notation . For an isotropic material, the ratio is one. Limitation of the Zener ratio to cubic materials is waived in the Tensorial anisotropy index A that takes into consideration all

1656-421: Is light coming through a polarizer . Another is wood , which is easier to split along its grain than across it because of the directional non-uniformity of the grain (the grain is the same in one direction, not all directions). In the field of computer graphics , an anisotropic surface changes in appearance as it rotates about its geometric normal , as is the case with velvet . Anisotropic filtering (AF)

1725-402: Is mainly used to separate solids from a hot solution. This is done to prevent crystal formation in the filter funnel and other apparatus that come in contact with the solution. As a result, the apparatus and the solution used are heated to prevent the rapid decrease in temperature which in turn, would lead to the crystallisation of the solids in the funnel and hinder the filtration process. One of

1794-445: Is of interest because, with knowledge of the anisotropy function as defined, a measurement of the BRDF from a single viewing direction (say, Ω v {\displaystyle \Omega _{v}} ) yields a measure of the total scene reflectance (planar albedo ) for that specific incident geometry (say, Ω i {\displaystyle \Omega _{i}} ). Filtration Filtration

1863-485: Is the shear modulus , E {\displaystyle E} is the Young's modulus , and ν {\displaystyle \nu } is the material's Poisson's ratio . Therefore, for cubic materials, we can think of anisotropy, a r {\displaystyle a_{r}} , as the ratio between the empirically determined shear modulus for the cubic material and its (isotropic) equivalent:

1932-416: Is the use of an ice bath to rapidly cool the solution to be crystallized rather than leaving it to cool slowly in the room atmosphere. This technique results in the formation of very small crystals as opposed to getting large crystals by cooling the solution at room temperature. Vacuum filtration technique is mostly preferred for small batches of solution to dry small crystals quickly. This method requires

2001-453: Is the variation of seismic wavespeed with direction. Seismic anisotropy is an indicator of long range order in a material, where features smaller than the seismic wavelength (e.g., crystals, cracks, pores, layers, or inclusions) have a dominant alignment. This alignment leads to a directional variation of elasticity wavespeed. Measuring the effects of anisotropy in seismic data can provide important information about processes and mineralogy in

2070-466: Is used, e.g., to determine the shape of a macromolecule. Anisotropy measurements reveal the average angular displacement of the fluorophore that occurs between absorption and subsequent emission of a photon. In NMR spectroscopy , the orientation of nuclei with respect to the applied magnetic field determines their chemical shift . In this context, anisotropic systems refer to the electron distribution of molecules with abnormally high electron density, like

2139-528: The Rotifera and the Ectoprocta . Many aquatic arthropods are filter feeders. Some use rhythmical beating of abdominal limbs to create a water current to the mouth whilst the hairs on the legs trap any particle. Others such as some caddis flies spin fine webs in the water flow to trap particles. Many filtration processes include more than one filtration mechanism, and particulates are often removed from

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2208-638: The glomerulus selectively removes undesirable constituents such as urea , followed by selective reabsorption of many substances essential for the body to maintain homeostasis. The complete process is termed excretion by urination . Similar but often less complex solutions are deployed in all animals, even the protozoa , where the contractile vacuole provides a similar function. Biofilms are often complex communities of bacteria, phages, yeasts and often more complex organisms including protozoa , rotifers and annelids which form dynamic and complex, frequently gelatinous films on wet substrates. Such biofilms coat

2277-486: The 27 components of the fully anisotropic stiffness tensor. It is composed of two major parts A I {\displaystyle A^{I}} and A A {\displaystyle A^{A}} , the former referring to components existing in cubic tensor and the latter in anisotropic tensor so that A T = A I + A A . {\displaystyle A^{T}=A^{I}+A^{A}.} This first component includes

2346-745: The Earth; significant seismic anisotropy has been detected in the Earth's crust , mantle , and inner core . Geological formations with distinct layers of sedimentary material can exhibit electrical anisotropy; electrical conductivity in one direction (e.g. parallel to a layer), is different from that in another (e.g. perpendicular to a layer). This property is used in the gas and oil exploration industry to identify hydrocarbon -bearing sands in sequences of sand and shale . Sand-bearing hydrocarbon assets have high resistivity (low conductivity), whereas shales have lower resistivity. Formation evaluation instruments measure this conductivity or resistivity, and

2415-472: The UV emission of the central stellar system. The Red Rectangle was the first nebula around an evolved star in which an equatorial disk in rotation was well identified (the existence of such disks has been demonstrated only in a few of these objects, only expansion is observed in most of them). However, the disk absorbs the stellar light and is practically not seen in the beautiful optical image, which mainly represents

2484-800: The X-like shape and the low velocity of the outflowing gas in the Red Rectangle are peculiar, probably because its origin (associated to a stable, extended disk) is different than for most protoplanetary nebulae. Anisotropic Anisotropy ( / ˌ æ n aɪ ˈ s ɒ t r ə p i , ˌ æ n ɪ -/ ) is the structural property of non-uniformity in different directions, as opposed to isotropy . An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical or mechanical properties when measured along different axes, e.g. absorbance , refractive index , conductivity , and tensile strength . An example of anisotropy

2553-546: The X-shaped nebular component, while the equatorial regions are known to contain silicate-rich dust grains and O-bearing molecules, was interpreted as due to a change of the O/C abundance ratio of the primary star during its late evolution. However, PAHs could also be formed as a result of the development of a central photodissociation region , a region in which a very active chemistry appears due to dissociation of stable molecules by

2622-409: The amount of equipment needed. Filter media are the materials used to do the separation of materials. Two main types of filter media are employed in laboratories: Surface filters allow the solid particles, i.e. the residue, to be collected intact; depth filters do not. However, the depth filter is less prone to clogging due to the greater surface area where the particles can be trapped. Also, when

2691-410: The biological component may be grown on a medium in the material being filtered. Removal of solids, emulsified components, organic chemicals and ions may be achieved by ingestion and digestion, adsorption or absorption. Because of the complexity of biological interactions, especially in multi-organism communities, it is often not possible to determine which processes are achieving the filtration result. At

2760-399: The cake is discarded or where the precipitate can be chemically separated from the filter. Filtration is a more efficient method for the separation of mixtures than decantation but is much more time-consuming. If very small amounts of solution are involved, most of the solution may be soaked up by the filter medium. An alternative to filtration is centrifugation . Instead of filtering

2829-548: The cosmic anisotropy in cosmic microwave background radiation in 1977. Their experiment demonstrated the Doppler shift caused by the movement of the earth with respect to the early Universe matter , the source of the radiation. Cosmic anisotropy has also been seen in the alignment of galaxies' rotation axes and polarization angles of quasars. Physicists use the term anisotropy to describe direction-dependent properties of materials. Magnetic anisotropy , for example, may occur in

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2898-410: The difference between horizontal and vertical permeability must be taken into account; otherwise the results may be subject to error. Most common rock-forming minerals are anisotropic, including quartz and feldspar . Anisotropy in minerals is most reliably seen in their optical properties . An example of an isotropic mineral is garnet . Igneous rock like granite also shows the anisotropy due to

2967-560: The direction of measurement. Fourth-rank tensor properties, like the elastic constants, are anisotropic, even for materials with cubic symmetry. The Young's modulus relates stress and strain when an isotropic material is elastically deformed; to describe elasticity in an anisotropic material, stiffness (or compliance) tensors are used instead. In metals, anisotropic elasticity behavior is present in all single crystals with three independent coefficients for cubic crystals, for example. For face-centered cubic materials such as nickel and copper,

3036-504: The directional dependence on properties is often related to the processing techniques it has undergone. A material with randomly oriented grains will be isotropic, whereas materials with texture will be often be anisotropic. Textured materials are often the result of processing techniques like cold rolling , wire drawing , and heat treatment . Mechanical properties of materials such as Young's modulus , ductility , yield strength , and high-temperature creep rate , are often dependent on

3105-571: The filter lattice, preventing the fluid phase from crossing the filter, known as blinding . The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size, filter thickness and biological activity). Filtration occurs both in nature and in engineered systems; there are biological , geological , and industrial forms. In everyday usage

3174-402: The filter medium and also give a clearer filtrate. They can also be added to the slurry before filtration. This increases the porosity of the cake and reduces the resistance of the cake during filtration. In a rotary filter, the filter aid may be applied as a precoat; subsequently, thin slices of this layer are sliced off with the cake. The use of filter aids is usually limited to cases where

3243-449: The filtration process faster, though this may lead to clogging or the passage of fine particles. Alternatively, the liquid may flow through the filter by the force exerted by a pump , a method commonly used in industry when a reduced filtration time is important. In this case, the filter need not be mounted vertically. Certain filter aids may be used to aid filtration. These are often incompressible diatomaceous earth , or kieselguhr, which

3312-466: The fluid first to prevent clogging of downstream elements. Particulate filtration includes: Adsorption filtration removes contaminants by adsorption of the contaminant by the filter medium. This requires intimate contact between the filter medium and the filtrate, and takes time for diffusion to bring the contaminant into direct contact with the medium while passing through it, referred to as dwell time . Slower flow also reduces pressure drop across

3381-428: The formation of biofilms on various filter media, and other factors have an impact on the growth structure and function of these biofilms. To conduct a thorough investigation of the composition, diversity, and dynamics of biofilms, it also takes on a variety of traditional and contemporary molecular approaches. Filter feeders are organisms that obtain their food by filtering their, generally aquatic, environment. Many of

3450-452: The heat source in electronics are often anisotropic. Many crystals are anisotropic to light ("optical anisotropy"), and exhibit properties such as birefringence . Crystal optics describes light propagation in these media. An "axis of anisotropy" is defined as the axis along which isotropy is broken (or an axis of symmetry, such as normal to crystalline layers). Some materials can have multiple such optical axes . Seismic anisotropy

3519-424: The location of the targeted material, i.e. whether it is dissolved in the fluid phase or suspended as a solid. There are several laboratory filtration techniques depending on the desired outcome namely, hot, cold and vacuum filtration . Some of the major purposes of obtaining the desired outcome are, for the removal of impurities from a mixture or, for the isolation of solids from a mixture. Hot filtration method

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3588-681: The material. Amorphous materials such as glass and polymers are typically isotropic. Due to the highly randomized orientation of macromolecules in polymeric materials, polymers are in general described as isotropic. However, mechanically gradient polymers can be engineered to have directionally dependent properties through processing techniques or introduction of anisotropy-inducing elements. Researchers have built composite materials with aligned fibers and voids to generate anisotropic hydrogels , in order to mimic hierarchically ordered biological soft matter. 3D printing, especially Fused Deposition Modeling, can introduce anisotropy into printed parts. This

3657-439: The mixture of solid and liquid particles, the mixture is centrifuged to force the (usually) denser solid to the bottom, where it often forms a firm cake . The liquid above can then be decanted. This method is especially useful for separating solids that do not filter well, such as gelatinous or fine particles. These solids can clog or pass through the filter, respectively. Biological filtration may take place inside an organism, or

3726-484: The modified Zener ratio and additionally accounts for directional differences in the material, which exist in orthotropic material, for instance. The second component of this index A A {\displaystyle A^{A}} covers the influence of stiffness coefficients that are nonzero only for non-cubic materials and remains zero otherwise. Fiber-reinforced or layered composite materials exhibit anisotropic mechanical properties, due to orientation of

3795-442: The molecular level, it may often be by individual catalytic enzyme actions within an individual organism. The waste products of some organisms may subsequently broken down by other organisms to extract as much energy as possible and in so doing reduce complex organic molecules to very simple inorganic species such as water, carbon dioxide and nitrogen. In mammals, reptiles, and birds, the kidneys function by renal filtration whereby

3864-410: The molecules. Liquid crystals are examples of anisotropic liquids. Some materials conduct heat in a way that is isotropic, that is independent of spatial orientation around the heat source. Heat conduction is more commonly anisotropic, which implies that detailed geometric modeling of typically diverse materials being thermally managed is required. The materials used to transfer and reject heat from

3933-446: The most important measures to prevent the formation of crystals in the funnel and to undergo effective hot filtration is the use stemless filter funnel. Due to the absence of a stem in the filter funnel, there is a decrease in the surface area of contact between the solution and the stem of the filter funnel, hence preventing re-crystallization of solid in the funnel, and adversely affecting the filtration process. Cold filtration method

4002-408: The orientation of the minerals during the solidification process. Anisotropy is also a well-known property in medical ultrasound imaging describing a different resulting echogenicity of soft tissues, such as tendons , when the angle of the transducer is changed. Tendon fibers appear hyperechoic (bright) when the transducer is perpendicular to the tendon, but can appear hypoechoic (darker) when

4071-475: The pi system of benzene . This abnormal electron density affects the applied magnetic field and causes the observed chemical shift to change. Images of a gravity-bound or man-made environment are particularly anisotropic in the orientation domain, with more image structure located at orientations parallel with or orthogonal to the direction of gravity (vertical and horizontal). Physicists from University of California, Berkeley reported about their detection of

4140-410: The protozoa are filter feeders using a range of adaptations including rigid spikes of protoplasm held in the water flow as in the suctoria to various arrangements of beating cillia to direct particles to the mouth including organisms such as Vorticella which have a complex ring of cilia which create a vortex in the flow drafting particles into the oral cavity. Similar feeding techniques are used by

4209-400: The reinforcement material. In many fiber-reinforced composites like carbon fiber or glass fiber based composites, the weave of the material (e.g. unidirectional or plain weave) can determine the extent of the anisotropy of the bulk material. The tunability of orientation of the fibers allows for application-based designs of composite materials, depending on the direction of stresses applied onto

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4278-430: The rest of the brain have less restricted movement and therefore display more isotropy. This difference in fractional anisotropy is exploited to create a map of the fiber tracts in the brains of the individual. Radiance fields (see Bidirectional reflectance distribution function (BRDF)) from a reflective surface are often not isotropic in nature. This makes calculations of the total energy being reflected from any scene

4347-434: The results are used to help find oil and gas in wells. The mechanical anisotropy measured for some of the sedimentary rocks like coal and shale can change with corresponding changes in their surface properties like sorption when gases are produced from the coal and shale reservoirs. The hydraulic conductivity of aquifers is often anisotropic for the same reason. When calculating groundwater flow to drains or to wells ,

4416-479: The rocks of most rivers and the sea and they provide the key filtration capability of the Schmutzdecke on the surface of slow sand filters and the film on the filter media of trickling filters which are used to create potable water and treat sewage respectively. An example of a biofilm is a biological slime, which may be found in lakes, rivers, rocks, etc. The utilization of single- or dual-species biofilms

4485-414: The screen without interrupting system flow. Fluids flow through a filter due to a pressure difference—fluid flows from the high-pressure side to the low-pressure side of the filter. The simplest method to achieve this is by gravity which can be seen in the coffeemaker example. In the laboratory, pressure in the form of compressed air on the feed side (or vacuum on the filtrate side) may be applied to make

4554-424: The solid particles are very fine, it is often cheaper and easier to discard the contaminated granules than to clean the solid sieve. Filter media can be cleaned by rinsing with solvents or detergents or backwashing. Alternatively, in engineering applications, such as swimming pool water treatment plants, they may be cleaned by backwashing . Self-cleaning screen filters utilize point-of-suction backwashing to clean

4623-508: The stiffness is highest along the <111> direction, normal to the close-packed planes, and smallest parallel to <100>. Tungsten is so nearly isotropic at room temperature that it can be considered to have only two stiffness coefficients; aluminium is another metal that is nearly isotropic. For an isotropic material, G = E / [ 2 ( 1 + ν ) ] , {\displaystyle G=E/[2(1+\nu )],} where G {\displaystyle G}

4692-412: The transducer is angled obliquely. This can be a source of interpretation error for inexperienced practitioners. Anisotropy, in materials science , is a material's directional dependence of a physical property . This is a critical consideration for materials selection in engineering applications. A material with physical properties that are symmetric about an axis that is normal to a plane of isotropy

4761-421: The verb "strain" is more often used; for example, using a colander to drain cooking water from cooked pasta . Filtration is also used to describe biological and physical systems that not only separate solids from a fluid stream but also remove chemical species and biological organisms by entrainment , phagocytosis , adsorption and absorption . Examples include slow sand filters and trickling filters . It

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