140 Sentences With "semipermeable" | Random Sentence Generator

These molecules are too large to pass through the semipermeable egg membrane.

The OLED layer is semipermeable, which makes it susceptible to moisture leaks.

We absorbed your politics by osmosis, across the semipermeable membrane of celluloid.

Reverse osmosis uses a semipermeable membrane as a filter to remove ions, molecules and large particles from water.

Reverse osmosis is a purification method that involves pushing salt water through a semipermeable membrane to remove the salt.

By applying pressure, saline water is forced through a semipermeable membrane–basically very thin plastic sheets with tiny holes in it.

Beyond the heliosphere's semipermeable boundary, known as the heliopause, particles originating from the sun become scarce ,and particles emanating from the rest of the galaxy dominate.

Now researchers have finally come up with a specially treated polymer that can serve as the semipermeable membrane needed to do reverse osmosis for chemicals manufacturing at room temperature.

This semipermeable filter acts like a cerebral nightclub bouncer, allowing helpful substances like water and glucose to flow from the bloodstream to the neurons, while denying access to potentially damaging molecules.

We need a politics of revisability; a politics that permits individuals to incorporate and embrace new thoughts and perspectives without bursting the semipermeable membrane that contains what's thinkable in the first place.

Desalination is usually achieved either by boiling salt water and collecting the steam, so that the salt is left behind, or reverse osmosis, which uses pressure to force saltwater through a semipermeable membrane that filters out salt and other particles.

"Our skin cells are meant to be plump and protected by their lipid barrier — an external, semipermeable wall that defends our cells from external elements while properly regulating the flow of nutrients and hydration to the cell," says Dr. Lancer.

A low concentration solution is created by adding a small amount of polymer to a solvent. This solution is separated from pure solvent by a semipermeable membrane. Solute cannot cross the semipermeable membrane but the solvent is able to cross the membrane. Solvent flows across the membrane to dilute the solution.

Although, liquid water will only move in response to such differences in osmotic potential if a semipermeable membrane exists between the zones of high and low osmotic potential. A semipermeable membrane is necessary because it allows water through its membrane while preventing solutes from moving through its membrane. If no membrane is present, movement of the solute, rather than of the water, largely equalizes concentrations. Since regions of soil are usually not divided by a semipermeable membrane, the osmotic potential typically has a negligible influence on the mass movement of water in soils.

How the membrane is constructed to be selective in its permeability will determine the rate and the permeability. Many natural and synthetic materials thicker than a membrane are also semipermeable. One example of this is the thin film on the inside of the egg. Note that a semipermeable membrane is not the same as a selectively permeable membrane.

The process of permeation involves the diffusion of molecules, called the permeant, through a membrane or interface. Permeation works through diffusion; the permeant will move from high concentration to low concentration across the interface. A material can be semipermeable, with the presence of a semipermeable membrane. Only molecules or ions with certain properties will be able to diffuse across such a membrane.

Semipermeable membrane describes a membrane that allows some particles to pass through (by size), whereas the selectively permeable membrane "chooses" what passes through (size is not a factor).

The osmotic pressure of the solvent across the semipermeable membrane is measured by the membrane osmometer. This osmotic pressure measurement is used to calculate M_n for the sample.

An alkali anion exchange membrane (AAEM) is a semipermeable membrane generally made from ionomers and designed to conduct anions while being impermeable to gases such as oxygen or hydrogen.

Other types of semipermeable membranes are cation exchange membrane (CEM), charge mosaic membrane (CMM), bipolar membrane (BPM), anion exchange membrane (AEM) alkali anion exchange membrane (AAEM) and proton exchange membrane (PEM).

In 1946 he develops tests of Reverse Osmosis, made with different types of semipermeable membranes. During this period he also develops patents relating to automatic changer, blood transfusion equipment, electrostatic toys.

The osmotic gradient is the difference in concentration between two solutions on either side of a semipermeable membrane, and is used to tell the difference in percentages of the concentration of a specific particle dissolved in a solution. Usually the osmotic gradient is used while comparing solutions that have a semipermeable membrane between them allowing water to diffuse between the two solutions, toward the hypertonic solution (the solution with the higher concentration). Eventually, the force of the column of water on the hypertonic side of the semipermeable membrane will equal the force of diffusion on the hypotonic (the side with a lesser concentration) side, creating equilibrium. When equilibrium is reached, water continues to flow, but it flows both ways in equal amounts as well as force, therefore stabilizing the solution.

Sweep gas, any gas used to flow through the hollow fiber, flows through RVOT catheter made up of hollow fiber with semipermeable walls to remove free, unbound water from ventricles in the form of water vapor.

Semipermeable membrane The principle of hemodialysis is the same as other methods of dialysis; it involves diffusion of solutes across a semipermeable membrane. Hemodialysis utilizes counter current flow, where the dialysate is flowing in the opposite direction to blood flow in the extracorporeal circuit. Counter-current flow maintains the concentration gradient across the membrane at a maximum and increases the efficiency of the dialysis. Fluid removal (ultrafiltration) is achieved by altering the hydrostatic pressure of the dialysate compartment, causing free water and some dissolved solutes to move across the membrane along a created pressure gradient.

This supports the assumption of a LUCA as a cellular organism, although primordial membranes may have been semipermeable and evolved later to the membranes of modern bacteria, and on a second path to those of modern archaea also.

The semipermeable membrane is pertinent to cellular communication. A cell membrane consists of proteins and phospholipids. Signaling molecules send chemical messages to the proteins in the cell membrane. The signaling molecules bind to proteins, which alters the protein structure.

Such a concentration gradient across a semipermeable membrane sets up an osmotic flow for the water. Osmosis, in biological systems involves a solvent, moving through a semipermeable membrane similarly to passive diffusion as the solvent still moves with the concentration gradient and requires no energy. While water is the most common solvent in cell, it can also be other liquids as well as supercritical liquids and gases. 2\. Transmembrane protein channels and transporters: Transmembrane proteins extend through the lipid bilayer of the membranes; they function on both sides of the membrane to transport molecules across it.

The Molecular Adsorbents Recirculation System (MARS) is the best known extracorporal liver dialysis system and has existed for approximately fifteen years. It consists of two separate dialysis circuits. The first circuit consists of human serum albumin, is in contact with the patient's blood through a semipermeable membrane and has two filters to clean the albumin after it has absorbed toxins from the patient's blood. The second circuit consists of a hemodialysis machine and is used to clean the albumin in the first circuit, before it is recirculated to the semipermeable membrane in contact with the patient's blood.

Osmosis in a U-shaped tube Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane. Osmosis occurs when two solutions containing different concentrations of solute are separated by a selectively permeable membrane.

As a result, the ionic groups in most ionomers will undergo microphase separation to form ionic-rich domains. Commercial applications for ionomers include golf ball covers, semipermeable membranes, sealing tape and thermoplastic elastomers. Common examples of ionomers include polystyrene sulfonate, Nafion and Hycar.

They hypothesized that this was due to a semipermeable membrane that protected the central nervous system from the passive diffusion of solutes in the bloodstream.Biedl, A; Kraus, R (1898). "Über eine bisher unbekannte toxische Wirkung der Gallensäure auf das Zentralnervensystem". Zentralbl. Inn.

The microdialysis technique requires the insertion of a small microdialysis catheter (also referred to as microdialysis probe) into the tissue of interest. The microdialysis probe is designed to mimic a blood capillary and consists of a shaft with a semipermeable hollow fiber membrane at its tip, which is connected to inlet and outlet tubing. The probe is continuously perfused with an aqueous solution (perfusate) that closely resembles the (ionic) composition of the surrounding tissue fluid at a low flow rate of approximately 0.1-5μL/min. Once inserted into the tissue or (body)fluid of interest, small solutes can cross the semipermeable membrane by passive diffusion.

Schematic of semipermeable membrane during hemodialysis, where blood is red, dialysing fluid is blue, and the membrane is yellow. Semipermeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by Osmosis—or occasionally by more specialized processes of facilitated diffusion, passive transport or active transport. The rate of passage depends on the pressure, concentration, and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute. Depending on the membrane and the solute, permeability may depend on solute size, solubility, properties, or chemistry.

In peritoneal dialysis, wastes and water are removed from the blood inside the body using the peritoneum as a natural semipermeable membrane. Wastes and excess water move from the blood, across the peritoneal membrane and into a special dialysis solution, called dialysate, in the abdominal cavity.

They function as a selective and semipermeable paracellular barrier between apical and basolateral compartments of the epithelial layer. They function to facilitate the passage of small ions and water-soluble solutes through the paracellular space while preventing the passage of luminal antigens, microorganisms and their toxins.

Van 't Hoff derived his analogy based on data from experiments that Wilhelm Pfeffer, a professor of botany, had published a decade earlier under the title "Osmotische Untersuchungen" -- an account of his endeavors to measure osmotic pressure by means of porous cells lined with a semipermeable membrane consisting of copper(II)-hexacyanoferrate(II). After van 't Hoff's theory was published, experimenters had trouble to replicate Pfeffer's measurements, mainly because they could not find or make clay cells of suitable quality to support the semipermeable membrane, a problem that had affected Pfeffer as well. Furthermore, Morse showed that Pfeffer's cells were leaky at high pressure. Morse's main experimental contribution was an electrolytic method of depositing semi-permeable membranes.

Many cells also have structures which exist wholly or partially outside the cell membrane. These structures are notable because they are not protected from the external environment by the semipermeable cell membrane. In order to assemble these structures, their components must be carried across the cell membrane by export processes.

The gastrointestinal tract is lined with epithelial cells. Drugs must pass or permeate through these cells in order to be absorbed into the circulatory system. One particular cellular barrier that may prevent absorption of a given drug is the cell membrane. Cell membranes are essentially lipid bilayers which form a semipermeable membrane.

The chemical garden relies on most transition metal silicates being insoluble in water and colored. When a metal salt, such as cobalt chloride, is added to a sodium silicate solution, it will start to dissolve. It will then form insoluble cobalt silicate by a double displacement reaction (anion metathesis). This cobalt silicate is a semipermeable membrane.

However, Mærsk emphasized that glass does not age well, so the façade was changed to a metal grid. The foyer floor is Sicilian Perlatino marble. The central foyer holds three spherical chandeliers created by the Icelandic artist Olafur Eliasson. Each chandelier consists of several pieces of glass, which are semipermeable allowing some light to pass, and some to reflect.

A process of osmosis through semipermeable membranes was first observed in 1748 by Jean-Antoine Nollet. For the following 200 years, osmosis was only a phenomenon observed in the laboratory. In 1950, the University of California at Los Angeles first investigated desalination of seawater using semipermeable membranes. Researchers from both University of California at Los Angeles and the University of Florida successfully produced fresh water from seawater in the mid-1950s, but the flux was too low to be commercially viable until the discovery at University of California at Los Angeles by Sidney Loeb and Srinivasa Sourirajan at the National Research Council of Canada, Ottawa, of techniques for making asymmetric membranes characterized by an effectively thin "skin" layer supported atop a highly porous and much thicker substrate region of the membrane.

Passive samplers were first developed in the early 1970s to monitor concentrations of airborne contaminants industrial workers might be exposed to, but by the 1990s researchers had developed and utilized passive samplers to monitor contaminants in the aqueous environment.Alvarez, D. 2013. Development of Semipermeable Membrane Devices (SPMDs) and Polar Organic Integrative Samplers (POCIS) for Environmental Monitoring. Environmental Toxicology and Chemistry.

23: 2179–2181. The first type of passive sampler made for use in the aqueous environment was the semipermeable membrane device (SPMD). SPMDs could be used to determine time-weighted average concentrations of hydrophobic organic contaminants, but until the early 2000s passive sampling devices for metal contaminants had not yet emerged. Metals in the environment can speciate into different forms.

An interface between the supplier and the embryo or fetus may be entirely artificial, e.g. by using one or more semipermeable membranes such as is used in extracorporeal membrane oxygenation (ECMO). There is also potential to grow a placenta using human endometrial cells. In 2002, it was announced that tissue samples from cultured endometrial cells removed from a human donor had successfully grown.

In the first part of the nephron, Bowman's capsule filters blood from the circulatory system into the tubules. Hydrostatic and osmotic pressure gradients facilitate filtration across a semipermeable membrane. The filtrate includes water, small molecules, and ions that easily pass through the filtration membrane. However larger molecules such as proteins and blood cells are prevented from passing through the filtration membrane.

Pore size is varied according to the size separation required with larger pore sizes allowing larger molecules to pass through the membrane. Solvents, ions and buffer can diffuse easily across the semipermeable membrane, but larger molecules are unable to pass through the pores. This can be used to purify proteins of interest from a complex mixture by removing smaller proteins and molecules.

The diffusion of water through a selectively permeable membrane is called osmosis. This allows only certain particles to go through including water and leaving behind the solutes including salt and other contaminants. In the process of reverse osmosis, thin film composite membranes (TFC or TFM) are used. These are semipermeable membranes manufactured principally for use in water purification or desalination systems.

Sally Blevins using her powers Sally Blevins is a mutant with power over a semipermeable personal protective deflection field. It provides nearly total protection from all attacks except those of insufficient force, like gas. Her force field disperses energy assaults, reflects kinetic impact off itself, and negates friction making it impossible to hold on to her. Skids cannot be grabbed or entangled when using her powers.

Unlike the EOP, the CPOP had no pre-formed hole in the outer shell for the drug to be expelled out of. Instead, the CPOP's semipermeable membrane was designed to form numerous small pores upon contact with water through which the drug would be expelled via osmotic pressure. The pores were formed via the use of a pH insensitive leachable or dissolvable additive such as sorbitol.

Liver cells obtained from an animal were used instead of developing a piece of equipment for each function of the liver. The structure and function of the first device also resembles that of today's BALs. Animal liver cells are suspended in a solution and a patient's blood is processed by a semipermeable membrane that allow toxins and blood proteins to pass but restricts an immunological response.

Mass-separating agents are other chemicals. They selectively dissolve or absorb one of the products; they are either a liquid (for sorption, extractive distillation or extraction) or a solid (for adsorption or ion exchange). The use of a barrier which restricts the movement of one compound but not of the other one (semipermeable membranes) is less common; external fields are used just in special applications.

Image:Hemodialysis-en.svg In hemodialysis, the patient's blood is pumped through the blood compartment of a dialyzer, exposing it to a partially permeable membrane. The dialyzer is composed of thousands of tiny hollow synthetic fibers. The fiber wall acts as the semipermeable membrane. Blood flows through the fibers, dialysis solution flows around the outside of the fibers, and water and wastes move between these two solutions.

Newts share many of the characteristics of their salamander kin, Caudata, including semipermeable glandular skin, four equal-sized limbs, and a distinct tail. The newt's skin, however, is not as smooth as that of other salamanders. Aquatic larvae have true teeth on both upper and lower jaws, and external gills. They have the ability to regenerate limbs, eyes, spinal cords, hearts, intestines, and upper and lower jaws.

Convenient pozzolanic materials to add to the mix may be, e.g., pozzolan, silica fume, fly ash, or metakaolin. These react preferentially with the cement alkalis without formation of an expansive pressure, because siliceous minerals in fine particles convert to alkali silicate and then to calcium silicate without formation of semipermeable reaction rims. #Another method to reduce the ASR is to limit the external alkalis that come in contact with the system.

Thin-film composite membranes (TFC or TFM) are semipermeable membranes manufactured principally for use in water purification or water desalination systems. They also have use in chemical applications such as batteries and fuel cells. A TFC membrane can be considered as a molecular sieve constructed in the form of a film from two or more layered materials. TFC membranes are commonly classified as nanofiltration (NF) and reverse osmosis (RO) membranes.

The increased demand for faster and easy-to-use protein separation tools has accelerated the evolution of IEF towards in-solution separations. In this context, a multi-junction IEF system was developed to perform fast and gel-free IEF separations. The multi-junction IEF system utilizes a series of vessels with a capillary passing through each vessel. Part of the capillary in each vessel is replaced by a semipermeable membrane.

The incoming flow starting at a low concentration has a semipermeable membrane with water passing to the buffer liquid via osmosis at a small gradient. There is a gradual buildup of concentration inside the loop until the loop tip where it reaches its maximum. Theoretically a similar system could exist or be constructed for heat exchange. In the example shown in the image, water enters at 299 mg/L (NaCl / H2O).

Differing salinity gradient power generations exist but one of the most commonly discussed is pressure-retarded osmosis (PRO). Within PRO seawater is pumped into a pressure chamber where the pressure is lower than the difference between fresh and salt water pressure. Fresh water moves in a semipermeable membrane and increases its volume in the chamber. As the pressure in the chamber is compensated a turbine spins to generate electricity.

The holes are filled with a culture medium that are then inoculated with soil diluted to deposit only one bacterium in each hole. After depositing the bacterium in the holes the iChip is covered on both sides by a semipermeable membrane and put into a box of the original soil. The permeable membranes allow nutrients and growth factors from the soil to diffuse in and allow growth of only one species. Ling et al.

Reverse osmosis is a water purification technology that uses a semipermeable membrane to remove ions, molecules, and larger particles from drinking water. Currently, reverse osmosis is the technology by which water reuse is made possible, in conjunction with filtering methods for larger solids (e.g., screens and settling tanks), other techniques for removing smaller particulates (e.g., aeration to allow bacteria to metabolize the suspended matter), and chlorination to kill any remaining harmful bacteria.

The leading process for desalination in terms of installed capacity and yearly growth is reverse osmosis (RO). The RO membrane processes use semipermeable membranes and applied pressure (on the membrane feed side) to preferentially induce water permeation through the membrane while rejecting salts. Reverse osmosis plant membrane systems typically use less energy than thermal desalination processes. Energy cost in desalination processes varies considerably depending on water salinity, plant size and process type.

Reverse osmosis uses an applied pressure gradient across a semipermeable membrane to overcome osmotic pressure and remove water molecules from the solution with hardness ions. The membrane has pores large enough to admit water molecules for passage; hardness ions such as Ca2+ and Mg2+ will not fit through the pores. The resulting soft water supply is free of hardness ions without any other ions being added. Membranes are a type of water filter requiring regular cleaning or replacement maintenance.

In thermodynamics, some extensive quantities measure amounts that are conserved in a thermodynamic process of transfer. They are transferred across a wall between two thermodynamic systems, or subsystems. For example, species of matter may be transferred through a semipermeable membrane. Likewise, volume may be thought of as transferred in a process in which there is a move of the wall between two systems, increasing the volume of one and decreasing that of the other by equal amounts.

The first artificial cells were developed by Thomas Chang at McGill University in the 1960s. These cells consisted of ultrathin membranes of nylon, collodion or crosslinked protein whose semipermeable properties allowed diffusion of small molecules in and out of the cell. These cells were micron-sized and contained cell, enzymes, hemoglobin, magnetic materials, adsorbents and proteins. Later artificial cells have ranged from hundred-micrometer to nanometer dimensions and can carry microorganisms, vaccines, genes, drugs, hormones and peptides.

One passive sampler, the semipermeable membrane device, or SPMD, is commonly used to measure organic contaminants in aquatic ecosystems. The SLMD was developed as a counterpart device for sampling metals. Passive sampling for trace metals is more complex than for organic toxicants as most dissolved metals can simultaneously exist in any of several ionic, complex-ion, and organically bound states. Metals can also bind with suspended or dissolved organic matter and exist as ultra-fine colloids, or lipophilic complexes.

In 1827, urea was first synthesized in the lab, confirming the composition of urea and making it the first biological substance synthesized. In 1856, urea was produced in vitro via oxidation of proteins. It was in 1850 that Thomas Dutrochet seeded the idea of dialysis with the discovery of separating smaller molecules from larger molecules through a semipermeable membrane. It was in 1829 and 1831 when convincing proof was obtained that in certain patients, blood urea was elevated.

Stainless steel rings, or other rigid inert material, are essential to prevent sorbent loss as the PES membranes are not able to be heat sealed. The POCIS array is then inserted and deployed within a protective canister. This canister is usually made of stainless steel or PVC and works to deflect debris that may displace the POCIS array during its deployment. The PES membrane acts as a semipermeable barrier between the sorbent and surrounding aquatic environment.

In cell biology, diffusion is a main form of transport for necessary materials such as amino acids within cells. Diffusion of solvents, such as water, through a semipermeable membrane is classified as osmosis. Metabolism and respiration rely in part upon diffusion in addition to bulk or active processes. For example, in the alveoli of mammalian lungs, due to differences in partial pressures across the alveolar-capillary membrane, oxygen diffuses into the blood and carbon dioxide diffuses out.

When a paint coating is applied on a metallic surface contaminated with soluble salts, an osmotic blistering process takes place (Figure 8.10). Osmosis is the spontaneous net movement of solvent molecules (water) through a semipermeable membrane (coating film) into a region of higher solute concentration (the salt contaminated substrate). The process drives to equalize the solute concentrations on the two sides, but because salt cannot pass through the membrane (coating) it can never equalize. Water continues to permeate into the region.

Another protocell model is the Jeewanu. First synthesized in 1963 from simple minerals and basic organics while exposed to sunlight, it is still reported to have some metabolic capabilities, the presence of semipermeable membrane, amino acids, phospholipids, carbohydrates and RNA-like molecules. However, the nature and properties of the Jeewanu remains to be clarified. Electrostatic interactions induced by short, positively charged, hydrophobic peptides containing 7 amino acids in length or fewer, can attach RNA to a vesicle membrane, the basic cell membrane.

Ultrafiltration (UF) is a variety of membrane filtration in which forces like 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.

An experimental demonstration may be considered. The two distinct gases, in a cylinder of constant total volume, are at first separated by two contiguous pistons made respectively of two suitably specific ideal semipermeable membranes. Ideally slowly and fictively reversibly, at constant temperature, the gases are allowed to mix in the volume between the separating membranes, forcing them apart, thereby supplying work to an external system. The energy for the work comes from the heat reservoir that keeps the temperature constant.

Osmosis is the movement of a solvent across a semipermeable membrane toward a higher concentration of solute (lower concentration of solvent). In biological systems, the solvent is typically water, but osmosis can occur in other liquids, supercritical liquids, and even gases. When a cell is submerged in water, the water molecules pass through the cell membrane from an area of low solute concentration to high solute concentration. For example, if the cell is submerged in saltwater, water molecules move out of the cell.

This system is not seen in animal cells, as the absence of a cell wall would cause the cell to lyse when under too much pressure. The pressure exerted by the osmotic flow of water is called turgidity. It is caused by the osmotic flow of water through a selectively permeable membrane. Osmotic flow of water through a semipermeable membrane is when the water travels from an area with a low-solute concentration, to one with a higher-solute concentration.

Turgor pressure within cells is regulated by osmosis and this also causes the cell wall to expand during growth. Along with size, rigidity of the cell is also caused by turgor pressure; a lower pressure results in a wilted cell or plant structure (i.e. leaf, stalk). One mechanism in plants that regulate turgor pressure is its semipermeable membrane, which only allows some solutes to travel in and out of the cell, which can also maintain a minimum amount of pressure.

Hemofiltration, also haemofiltration, is a renal replacement therapy which is used in the intensive care setting. It is usually used to treat acute kidney injury (AKI), but may be of benefit in multiple organ dysfunction syndrome or sepsis. During hemofiltration, a patient's blood is passed through a set of tubing (a filtration circuit) via a machine to a semipermeable membrane (the filter) where waste products and water (collectively called ultrafiltrate) are removed by convection. Replacement fluid is added and the blood is returned to the patient.

Nerve guidance channels, Nerve guidance conduit are innovative strategies focusing on larger defects that provide a conduit for sprouting axons directing growth and reducing growth inhibition from scar tissue. Nerve guidance channels must be readily formed into a conduit with the desired dimensions, sterilizable, tear resistant, and easy to handle and suture (Schmidt & Leach 2003). Ideally they would degrade over time with nerve regeneration, be pliable, semipermeable, maintain their shape, and have a smooth inner wall that mimics that of a real nerve (Schmidt & Leach 2003).

Diagram showing the basic physiologic mechanisms of the kidney In renal physiology, ultrafiltration occurs at the barrier between the blood and the filtrate in the glomerular capsule (Bowman's capsule) in the kidneys. As in nonbiological examples of ultrafiltration, pressure (in this case blood pressure) and concentration gradients lead to a separation through a semipermeable membrane (provided by the podocytes). The Bowman's capsule contains a dense capillary network called the glomerulus. Blood flows into these capillaries through the afferent arterioles and leaves through the efferent arterioles.

New York, NY; 2008:14–21 In Australia, Canada, the United Kingdom, and the United States, dialysis is paid for by the government for those who are eligible. In research laboratories, dialysis technique can also be used to separate molecules based on their size. Additionally, it can be used to balance buffer between a sample and the solution "dialysis bath" or "dialysate" that the sample is in. For dialysis in a laboratory, a tubular semipermeable membrane made of cellulose acetate or nitrocellulose is used.

First-use syndrome is a rare but severe anaphylactic reaction to the artificial kidney. Its symptoms include sneezing, wheezing, shortness of breath, back pain, chest pain, or sudden death. It can be caused by residual sterilant in the artificial kidney or the material of the membrane itself. In recent years, the incidence of first-use syndrome has decreased, due to an increased use of gamma irradiation, steam sterilization, or electron-beam radiation instead of chemical sterilants, and the development of new semipermeable membranes of higher biocompatibility.

Semipermeable membrane devices (SPMDs) passively sample nonpolar organic contaminants with a log octanol-water partition coefficient (Kow) value greater than 3. Examples of these types of chemicals include polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), chlorinated pesticides, dioxins, and furans. SPMDs are composed of sealed plastic tubing filled with triolein, in which nonpolar organics are very soluble and which serves as a representation of the fatty tissues of aquatic organisms. The tubing is then weaved between metal rods and enclosed in a metal cage.

"Diagram Illustrating the Malate-Aspartate Shuttle Pathway" The malate- aspartate shuttle (sometimes simply the malate shuttle) is a biochemical system for translocating electrons produced during glycolysis across the semipermeable inner membrane of the mitochondrion for oxidative phosphorylation in eukaryotes. These electrons enter the electron transport chain of the mitochondria via reduction equivalents to generate ATP. The shuttle system is required because the mitochondrial inner membrane is impermeable to NADH, the primary reducing equivalent of the electron transport chain. To circumvent this, malate carries the reducing equivalents across the membrane.

The water potential between fresh water (right) and sea water (left) corresponds to a hydraulic head of 270 metres Pressure retarded osmosis (PRO) is a technique to separate a solvent (for example, fresh water) from a solution that is more concentrated (e.g. sea water) and also pressurized. A semipermeable membrane allows the solvent to pass to the concentrated solution side by osmosis. The technique can be used to generate power from the salinity gradient energy resulting from the difference in the salt concentration between sea and river water.

A 54mg tablet of Concerta, which uses OROS technology. Osmotic controlled- release oral delivery systems (OROS) have the form of a rigid tablet with a semi-permeable outer membrane and one or more small laser drilled holes in it. As the tablet passes through the body, water is absorbed through the semipermeable membrane via osmosis, and the resulting osmotic pressure is used to push the active drug through the opening(s) in the tablet. OROS is a trademarked name owned by ALZA Corporation, which pioneered the use of osmotic pumps for oral drug delivery.

The barrel set behaves essentially as a device for vinegar concentration due to water loss through the staves. As widely known for the wine production, it is reasonable to suppose that the wood acts as a semipermeable filter for the transfer of small molecules towards the ambient while it retains important volatile compounds such as the acetic acid. However, when the opening is not hermetically closed, the volatile compounds are lost preferentially through the cocchiume itself.Giudici, P.; Solieri, L.; De Vero, L.; Landi, S.; Pulvirenti, A.; Rainieri, S. (2006).

Like all amphibians, the long-toed salamander has both an aquatic and terrestrial life transition and semipermeable skin. Since they serve different ecological functions in the water than they do in land, the loss of one amphibian species is equivalent to the loss of two ecological species. The second notion is that amphibians, such as long-toed salamanders, are more susceptible to the absorption of pollutants because they naturally absorb water and oxygen through their skin. The validity of this special sensitivity to environmental pollutants, however, has been called into question.

Gaseous diffusion uses semi-permeable membranes to separate enriched uranium Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride (UF6) through semipermeable membranes. This produces a slight separation between the molecules containing uranium-235 (235U) and uranium-238 (238U). By use of a large cascade of many stages, high separations can be achieved. It was the first process to be developed that was capable of producing enriched uranium in industrially useful quantities, but is nowadays considered obsolete, having been superseded by the more-efficient gas centrifuge process.

The granule is the defining characteristic of the endoplasm, as they are typically not present within the ectoplasm. These offshoots of the endomembrane system are enclosed by a phospholipid bilayer and can fuse with other organelles as well as the plasma membrane. Their membrane is only semipermeable and allows them to house substances that could be harmful to the cell if they were allowed to flow freely within the cytosol. These granules give the cell a large amount of regulation and control over the wide variety of metabolic activities that take place within the endoplasm.

Villi increase the internal surface area of the intestinal walls making available a greater surface area for absorption. An increased absorptive area is useful because digested nutrients (including monosaccharide and amino acids) pass into the semipermeable villi through diffusion, which is effective only at short distances. In other words, increased surface area (in contact with the fluid in the lumen) decreases the average distance travelled by nutrient molecules, so effectiveness of diffusion increases. The villi are connected to the blood vessels so the circulating blood then carries these nutrients away.

Three topologies of countercurrent exchange systems Countercurrent exchange along with cocurrent exchange and contra-current exchange comprise the mechanisms used to transfer some property of a fluid from one flowing current of fluid to another across a barrier allowing one way flow of the property between them. The property transferred could be heat, concentration of a chemical substance, or other properties of the flow. When heat is transferred, a thermally-conductive membrane is used between the two tubes, and when the concentration of a chemical substance is transferred a semipermeable membrane is used.

Eukaryotic cell membrane Comparison of Eukaryotes vs. Prokaryotes The cell membrane (also known as the plasma membrane, or cytoplasmic membrane, and historically referred to as the plasmalemma) is the semipermeable membrane of a cell that surrounds and encloses its contents of cytoplasm and nucleoplasm. The cell membrane separates the cell from the surrounding interstitial fluid, the main component of the extracellular fluid.Kimball's Biology pages , Cell Membranes The cell membrane consists of a lipid bilayer, including cholesterols (a lipid component) that sit between phospholipids to maintain their fluidity at various temperatures.

Osmosis diffusion ultrafiltration and dialysis The two main types of dialysis, hemodialysis and peritoneal dialysis, remove wastes and excess water from the blood in different ways. Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite. The counter-current flow of the blood and dialysate maximizes the concentration gradient of solutes between the blood and dialysate, which helps to remove more urea and creatinine from the blood.

In his time he was especially noted for his clarification of the role of nutrients in metabolism and his work with semipermeable membranes. The University of Halle-Wittenberg conferred an honorary doctorate of medicine on Traube in 1867 and he was elected a corresponding member of the Prussian Academy of Sciences in Berlin in 1886. Louis Pasteur called Traube an excellent physiologist and professor; extensive appreciations were written by August Wilhelm von Hofmann, Hermann Emil Fischer and Ferdinand Cohn. In 1875 Charles Darwin had asked Traube to send him his work on cell formation.

Many have played a role in developing dialysis as a practical treatment for renal failure, starting with Thomas Graham of Glasgow, who first presented the principles of solute transport across a semipermeable membrane in 1854.Graham T. The Bakerian lecture: on osmotic force. Philosophical Transactions of the Royal Society in London. 1854;144:177–228. The artificial kidney was first developed by Abel, Rountree, and Turner in 1913,Abel, J. J., Rountree, L. G., and Turner, B. B. The removal of diffusible substances from the circulating blood by means of dialysis.

An example of a biological semi- permeable membrane is the lipid bilayer, on which is based on the plasma membrane that surrounds all biological cells. A group of phospholipids (consisting of a phosphate head and two fatty acid tails) arranged into a double layer, the phospholipid bilayer is a semipermeable membrane that is very specific in its permeability. The hydrophilic phosphate heads are in the outside layer and exposed to the water content outside and within the cell. The hydrophobic tails are the layer hidden in the inside of the membrane.

Osmotic pressure is a colligative property, meaning that the osmotic pressure depends on the molar concentration of the solute but not on its identity. Osmosis is a vital process in biological systems, as biological membranes are semipermeable. In general, these membranes are impermeable to large and polar molecules, such as ions, proteins, and polysaccharides, while being permeable to non-polar or hydrophobic molecules like lipids as well as to small molecules like oxygen, carbon dioxide, nitrogen, and nitric oxide. Permeability depends on solubility, charge, or chemistry, as well as solute size.

At 11:44 a.m. on October 21, 2017, the small Maine town of Chester's Mill is abruptly and gruesomely separated from the outside world by an invisible, semipermeable barrier of unknown origin. The immediate appearance of the barrier causes a number of injuries and fatalities and traps former Army Captain Dale "Barbie" Barbara—who is trying to leave Chester's Mill because of a local dispute—inside the town. Police Chief Howard "Duke" Perkins is killed instantly when his pacemaker explodes when he gets too close to the Dome.

Since the invention of the microscope in the seventeenth century it has been known that plant and animal tissue is composed of cells : the cell was discovered by Robert Hooke. The plant cell wall was easily visible even with these early microscopes but no similar barrier was visible on animal cells, though it stood to reason that one must exist. By the mid 19th century, this question was being actively investigated and Moritz Traube noted that this outer layer must be semipermeable to allow transport of ions.Jacques Loeb, The Dynamics of Living Matter.

In this view, the membrane is not a pure lipid layer, but a mosaic of areas with lipid and areas with semipermeable gel. Ruhland refined the mosaic theory to include pores to allow additional passage of small molecules. Since membranes are generally less permeable to anions, Leonor Michaelis concluded that ions are adsorbed to the walls of the pores, changing the permeability of the pores to ions by electrostatic repulsion. Michaelis demonstrated the membrane potential (1926) and proposed that it was related to the distribution of ions across the membrane.

As support for the lipid bilayer membrane theory grew, this alternative concept was developed which denied the importance of the lipid bilayer membrane. Procter & Wilson (1916) demonstrated that gels, which do not have a semipermeable membrane, swelled in dilute solutions. Loeb (1920) also studied gelatin extensively, with and without a membrane, showing that more of the properties attributed to the plasma membrane could be duplicated in gels without a membrane. In particular, he found that an electrical potential difference between the gelatin and the outside medium could be developed, based on the H+ concentration.

Small-molecule dialysis using dialysis tubingIn biochemistry, dialysis is the process of separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane, such as dialysis tubing. Dialysis is a common laboratory technique that operates on the same principle as medical dialysis. In the context of life science research, the most common application of dialysis is for the removal of unwanted small molecules such as salts, reducing agents, or dyes from larger macromolecules such as proteins, DNA, or polysaccharides. Dialysis is also commonly used for buffer exchange and drug binding studies.

Once equilibrium is reached, the final concentration of molecules is dependent on the volumes of the solutions involved, and if the equilibrated dialysate is replaced (or exchanged) with fresh dialysate (see procedure below), diffusion will further reduce the concentration of the small molecules in the sample. Dialysis can be used to either introduce or remove small molecules from a sample, because small molecules move freely across the membrane in both directions. This makes dialysis a useful technique for a variety of applications. See dialysis tubing for additional information on the history, properties, and manufacturing of semipermeable membranes used for dialysis.

Vernix provides electrical isolation for the fetus, which is presumably an important aspect of developing fetal anatomy. Early scientific studies indicated increased evaporative heat loss in infants when vernix was removed soon after birth; but newer reports confirm that washing skin surface after birth reduces evaporative water losses compared to surface of newborns in which vernix is left in situ.Riesenfeld B, Stromberg B, Sedin G. The influence of vernix caseosa on water transport through semipermeable membranes and the skin of full-term infants. Neonatal Physiological Measurements: Proceedings of the Second International Conference on Fetal and Neonatal Physiological Measurements, 1984:3–6.

The osmotic-controlled release oral delivery system (OROS) is an advanced controlled release oral drug delivery system in the form of a rigid tablet with a semi-permeable outer membrane and one or more small laser drilled holes in it. As the tablet passes through the body, water is absorbed through the semipermeable membrane via osmosis, and the resulting osmotic pressure is used to push the active drug through the laser drilled opening(s) in the tablet and into the gastrointestinal tract. OROS is a trademarked name owned by ALZA Corporation, which pioneered the use of osmotic pumps for oral drug delivery.

Donnan potential appears as a result of Donnan equilibrium, named after Frederick G. Donnan, which refers to the distribution of ion species between two ionic solutions separated by a semipermeable membrane or boundary. The boundary layer maintains an unequal distribution of ionic solute concentration by acting as a selective barrier to ionic diffusion. Some species of ions may pass through the barrier while others may not. The solutions may be gels or colloids as well as ionic liquids, and as such the phase boundary between gels or a gel and a liquid can also act as a selective barrier.

Effect of different solutions on red blood cells Micrographs of osmotic pressure on red blood cells Tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a semipermeable cell membrane. In other words, tonicity is the relative concentration of solutes dissolved in solution which determine the direction and extent of diffusion. It is commonly used when describing the response of cells immersed in an external solution. Unlike osmotic pressure, tonicity is influenced only by solutes that cannot cross the membrane, as only these exert an effective osmotic pressure.

A proton-exchange membrane, or polymer-electrolyte membrane (PEM), is a semipermeable membrane generally made from ionomers and designed to conduct protons while acting as an electronic insulator and reactant barrier, e.g. to oxygen and hydrogen gas. This is their essential function when incorporated into a membrane electrode assembly (MEA) of a proton-exchange membrane fuel cell or of a proton-exchange membrane electrolyser: separation of reactants and transport of protons while blocking a direct electronic pathway through the membrane. PEMs can be made from either pure polymer membranes or from composite membranes, where other materials are embedded in a polymer matrix.

An anion exchange membrane (AEM) is a semipermeable membrane generally made from ionomers and designed to conduct anions while being impermeable to gases such as oxygen or hydrogen. Anion exchange membranes are used in electrolytic cells and fuel cells to separate reactants present around the two electrodes while transporting the anions essential for the cell operation. An important example is the hydroxide anion exchange membrane used to separate the electrodes of a direct methanol fuel cell (DMFC)Comparison of PVDF and FEP based radiation-grafted alkaline anionexchange membranes for use in low temperature portable DMFCs or direct-ethanol fuel cell (DEFC).

Surfactant molecules arranged on an air – water interface Jeewanu protocells are synthetic chemical particles that possess cell-like structure and seem to have some functional living properties. First synthesized in 1963 from simple minerals and basic organics while exposed to sunlight, it is still reported to have some metabolic capabilities, the presence of semipermeable membrane, amino acids, phospholipids, carbohydrates and RNA-like molecules. However, the nature and properties of the Jeewanu remains to be clarified. In a similar synthesis experiment a frozen mixture of water, methanol, ammonia and carbon monoxide was exposed to ultraviolet (UV) radiation.

St. Louis, MO; Mosby: 2006 Blood flows by one side of a semi-permeable membrane, and a dialysate, or special dialysis fluid, flows by the opposite side. A semipermeable membrane is a thin layer of material that contains holes of various sizes, or pores. Smaller solutes and fluid pass through the membrane, but the membrane blocks the passage of larger substances (for example, red blood cells and large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus.

In 1864 Traube was the first to produce artificial semipermeable membranes, recognizing them as molecular sieves and using them in developing the first physical-chemical theory of plant cell growth. The artificial cells were created by putting droplets of glue in tannic acid; these grew under infusion of water. (Other membranes were created with tannic acid plus verdigris or potassium ferrocyanide plus copper chloride). These membranes laid the foundation for research into osmotic pressure in solutions (Wilhelm Pfeffer and Jacobus Henricus van 't Hoff used them), and Traube himself did research on the manifestations of diffusion and osmosis.

Due to the constant perfusion of the microdialysis probe with fresh perfusate, a total equilibrium cannot be established. This results in dialysate concentrations that are lower than those measured at the distant sampling site. In order to correlate concentrations measured in the dialysate with those present at the distant sampling site, a calibration factor (recovery) is needed. The recovery can be determined at steady-state using the constant rate of analyte exchange across the microdialysis membrane. The rate at which an analyte is exchanged across the semipermeable membrane is generally expressed as the analyte’s extraction efficiency.

The major weakness of the lipid membrane was the lack of an explanation of the high permeability to water, so Nathansohn (1904) proposed the mosaic theory. In this view, the membrane is not a pure lipid layer, but a mosaic of areas with lipid and areas with semipermeable gel. Ruhland refined the mosaic theory to include pores to allow additional passage of small molecules. Since membranes are generally less permeable to anions, Leonor Michaelis concluded that ions are adsorbed to the walls of the pores, changing the permeability of the pores to ions by electrostatic repulsion.

The use of passive samplers greatly reduces the cost and the need of infrastructure on the sampling location. Passive samplers are semi-disposable and can be produced at a relatively low cost, thus they can be employed in great numbers, allowing for a better cover and more data being collected. Due to being small the passive sampler can also be hidden, and thereby lower the risk of vandalism. Examples of passive sampling devices are the diffusive gradients in thin films (DGT) sampler, Chemcatcher, Polar organic chemical integrative sampler (POCIS), semipermeable membrane devices (SPMDs), stabilized liquid membrane devices (SLMDs), and an air sampling pump.

Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An example of this would be the formation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H+) across a membrane during cellular respiration or photosynthesis. An ion gradient has potential energy and can be used to power chemical reactions when the ions pass through a channel (red). Hydrogen ions, or protons, will diffuse from an area of high proton concentration to an area of lower proton concentration, and an electrochemical concentration gradient of protons across a membrane can be harnessed to make ATP.

Jeewanu (Sanskrit for "particles of life") are synthetic chemical particles that possess cell-like structure and seem to have some functional properties; that is, they are a model of primitive cells, or protocells. It was first synthesised by Krishna Bahadur (20 January 1926 — 5 August 1994), an Indian chemist and his team in 1963. Using photochemical reaction, they produced coacervates, microscopic cell-like spheres from a mixture of simple organic and inorganic compounds. Bahadur named these particles 'Jeewanu' because they exhibit some of the basic properties of a cell, such as the presence of semipermeable membrane, amino acids, phospholipids and carbohydrates.

The lipid nature of the cell membrane was first correctly intuited by Quincke, who noted that a cell generally forms a spherical shape in water and, when broken in half, forms two smaller spheres. The only other known material to exhibit this behavior was oil. He also noted that a thin film of oil behaves as a semipermeable membrane, precisely as predicted. Based on these observations, Quincke asserted that the cell membrane comprised a fluid layer of fat less than 100 nm thick.O Hertwig, M Campbell, and H J Campbell, “The Cell: Outlines of General Anatomy and Physiology.” 1895.

Many other medical conditions have been targeted with encapsulation therapies, especially those involving a deficiency in some biologically derived protein. One of the most successful approaches is an external device that acts similarly to a dialysis machine, only with a reservoir of pig hepatocytes surrounding the semipermeable portion of the blood-infused tubing. This apparatus can remove toxins from the blood of patients suffering severe liver failure. Other applications that are still in development include cells that produce ciliary-derived neurotrophic factor for the treatment of ALS and Huntington's disease, glial-derived neurotrophic factor for Parkinson's disease, erythropoietin for anemia, and HGH for dwarfism.

In addition, passive samplers are often easy to use and deploy, have no pumps or moving parts, and do not require electricity, since they rely on the molecular diffusion of contaminants or binding of contaminants to agents within the samplers, unlike active sampling. They may also be inexpensive and simple to construct, such as SLMDs, which only require sealed plastic tubing and two chemical components. Passive sampling may also more accurately reflect metal concentrations that are bioavailable to organisms than other sampling methods. For example, the SPMD sampler uses a semipermeable membrane and triolein (a triglyceride), both of which mimic toxicant uptake by organism fatty tissue.

The reason why the precipitation temporarily or permanently stops in these regions is that the oblique, passive edges of the precipitate act as a semipermeable membrane, blocking the diffusion of the outer electrolyte . The mechanism behind the regression of the active front segments is not fully understood. It is believed that a diffusive intermediate compound forms at the active segments having reduced concentration at the sides, and a critical concentration is required for the precipitation to occur. When the outer electrolyte is poured onto the top of a gel column in a glass tube, the diffusion front takes roughly the form of a disk.

The chip is then enclosed in a semipermeable plastic membrane and buried back in the dirt to allow in nutrients not available in the lab. With this culturing method, about 50 to 60 percent of bacterial species are able to survive. Notably, the bacterial species Eleftheria terrae, which makes the antibiotic teixobactin that has shown promise against many drug-resistant strains like methicillin-resistant Staphylococcus aureus, was discovered using the ichip in 2015. In addition to antibiotics, it is argued that anti-cancer agents, anti-inflammatory and immunosuppressives (which have previously been discovered from bacteria) as well as potential energy sources could be discovered.

One of the main goals of nanoneuroscience is to gain a detailed understanding of how the nervous system operates and, thus, how neurons organize themselves in the brain. Consequently, creating drugs and devices that are able to cross the blood brain barrier (BBB) are essential to allow for detailed imaging and diagnoses. The blood brain barrier functions as a highly specialized semipermeable membrane surrounding the brain, preventing harmful molecules that may be dissolved in the circulation blood from entering the central nervous system. The main two hurdles for drug-delivering molecules to access the brain are size (must have a molecular weight < 400 Da) and lipid solubility.

A colloid being something between a solution and a suspension, where Brownian motion is sufficient to prevent sedimentation. The idea of a semipermeable membrane, a barrier that is permeable to solvent but impermeable to solute molecules was developed at about the same time. The term osmosis originated in 1827 and its importance to physiological phenomena realized, but it wasn’t until 1877, when the botanist Pfeffer proposed the membrane theory of cell physiology. In this view, the cell was seen to be enclosed by a thin surface, the plasma membrane, and cell water and solutes such as a potassium ion existed in a physical state like that of a dilute solution.

The idea of a semipermeable membrane, a barrier that is permeable to solvent but impermeable to solute molecules was developed at about the same time. The term osmosis originated in 1827 and its importance to physiological phenomena realized, but it was not until 1877 when the botanist Wilhelm Pfeffer proposed the membrane theory of cell physiology. In this view, the cell was seen to be enclosed by a thin surface, the plasma membrane, and cell water and solutes such as a potassium ion existed in a physical state like that of a dilute solution. In 1889, Hamburger used hemolysis of erythrocytes to determine the permeability of various solutes.

Lewandowsky coined the term "Blood–brain barrier" in 1900, referring to the hypothesized semipermeable membrane which separated the human central nervous system from the rest of the body's vasculature, and which prevented the entry of certain compounds from entering the brain when injected into the bloodstream. Two years earlier, researchers Arthur Biedl and R. Kraus had formed a similar hypothesis when low-concentration "bile salts" failed to affect behavior (and thus, in theory, had failed to enter the brain) when injected into the bloodstream of animals. Beginning in 1910 he, together with Alois Alzheimer, edited the journal Zeitschrift für die gesamte Neurologie und Psychiatrie. He was also editor of a handbook of neurology, Handbuch der Neurologie (1910–14).

In biomedicine and biotechnology, sensors which detect analytes thanks to a biological component, such as cells, protein, nucleic acid or biomimetic polymers, are called biosensors. Whereas a non-biological sensor, even organic (carbon chemistry), for biological analytes is referred to as sensor or nanosensor. This terminology applies for both in-vitro and in vivo applications. The encapsulation of the biological component in biosensors, presents a slightly different problem that ordinary sensors; this can either be done by means of a semipermeable barrier, such as a dialysis membrane or a hydrogel, or a 3D polymer matrix, which either physically constrains the sensing macromolecule or chemically constrains the macromolecule by bounding it to the scaffold.

A machinist on a lathe Tool and die makers are a class of machinists in the manufacturing industries. Variations on the name include tool maker, toolmaker, die maker, diemaker, mold maker, moldmaker or tool jig and die- maker, or Fitter, depend on which area of concentration or industry an individual works in. Tool and die makers work primarily in toolroom environments—sometimes literally in one room but more often in an environment with flexible, semipermeable boundaries from production work. They are skilled artisans (craftspeople) who typically learn their trade through a combination of academic coursework and hands-on instruction, with a substantial period of on-the-job training that is functionally an apprenticeship (although usually not nominally today).

Following this, estradiol is then taken up by local capillary blood vessels and delivered into the circulation. There is a depot effect in the skin with transdermal estradiol, which results in continuous delivery of transdermal estradiol into the circulation. This is because the skin functions as a semipermeable membrane and there is a concentration gradient between the application site of transdermal estradiol and capillary blood, with the rate of diffusion of estradiol across the stratum corneum being the specific rate- limiting factor in absorption. As a result, peaks and troughs in circulating estradiol levels are limited, and the skin and subcutaneous fat act as a reservoir of estradiol that maintains circulating estradiol levels between doses.

Osmotic concentration, formerly known as osmolarity,IUPAC goldbook is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). The osmolarity of a solution is usually expressed as Osm/L (pronounced "osmolar"), in the same way that the molarity of a solution is expressed as "M" (pronounced "molar"). Whereas molarity measures the number of moles of solute per unit volume of solution, osmolarity measures the number of osmoles of solute particles per unit volume of solution. This value allows the measurement of the osmotic pressure of a solution and the determination of how the solvent will diffuse across a semipermeable membrane (osmosis) separating two solutions of different osmotic concentration.

In 1942, at the outset of the Manhattan Project, three methods of uranium enrichment were under consideration: gaseous diffusion, thermal diffusion, and electromagnetic separation. The gaseous diffusion method involves passing uranium hexafluoride (UF6) gas through a series of semipermeable membranes to achieve the separation of the fissionable uranium-235 (235U) isotope from the more abundant but non-fissile isotope uranium-238 (238U). It was first necessary however to develop non-reactive chemical compounds that could be used as coatings, lubricants and gaskets for the surfaces which would come into contact with the UF6 gas, which is a highly reactive and corrosive substance. Because of Miller's expertise in organofluorine chemistry, he was recruited by scientists of the Manhattan Project to synthesize and develop such materials.

She is also able to make her shields opaque or translucent like milk glass to effectively block variations of light such as laser-beams, or make them semipermeable to filter oxygen from water though the latter is mentally taxing. She can generate solid force constructs as small as a marble or as large as in diameter, and her hollow projections such as domes can extend up to several miles in area. By generating additional force behind her psionic constructs, Sue can turn them into offensive weapons, ranging from massive invisible battering rams to small projectiles such as spheres and darts. By forming one of her force fields within an object and expanding the field, Sue can cause her target to explode.

Michaelis demonstrated the membrane potential (1926) and proposed that it was related to the distribution of ions across the membrane. Harvey and Danielli (1939) proposed a lipid bilayer membrane covered on each side with a layer of protein to account for measurements of surface tension. In 1941 Boyle & Conway showed that the membrane of frog muscle was permeable to both and , but apparently not to , so the idea of electrical charges in the pores was unnecessary since a single critical pore size would explain the permeability to , , and as well as the impermeability to , , and . Over the same time period, it was shown (Procter & Wilson, 1916) that gels, which do not have a semipermeable membrane, would swell in dilute solutions.

The osmotic pressure of a solution is the difference in pressure between the solution and the pure liquid solvent when the two are in equilibrium across a semipermeable membrane, which allows the passage of solvent molecules but not of solute particles. If the two phases are at the same initial pressure, there is a net transfer of solvent across the membrane into the solution known as osmosis. The process stops and equilibrium is attained when the pressure difference equals the osmotic pressure. Two laws governing the osmotic pressure of a dilute solution were discovered by the German botanist W. F. P. Pfeffer and the Dutch chemist J. H. van’t Hoff: # The osmotic pressure of a dilute solution at constant temperature is directly proportional to its concentration.

The microdialysis principle was first employed in the early 1960s, when push-pull canulas and dialysis sacs were implanted into animal tissues, especially into rodent brains, to directly study the tissues' biochemistry. While these techniques had a number of experimental drawbacks, such as the number of samples per animal or no/limited time resolution, the invention of continuously perfused dialytrodes in 1972 helped to overcome some of these limitations. Further improvement of the dialytrode concept resulted in the invention of the "hollow fiber", a tubular semipermeable membrane with a diameter of ~200-300μm, in 1974. Today's most prevalent shape, the needle probe, consists of a shaft with a hollow fiber at its tip and can be inserted by means of a guide cannula into the brain and other tissues.

In contrast to the established customary usage, "mixing" might be conducted reversibly at constant volume for each of two fixed masses of gases of equal volume, being mixed by gradually merging their initially separate volumes by use of two ideal semipermeable membranes, each permeable only to one of the respective gases, so that the respective volumes available to each gas remain constant during the merge. Either one of the common temperature or the common pressure is chosen to be independently controlled by the experimenter, the other being allowed to vary so as to maintain constant volume for each mass of gas. In this kind of "mixing", the final common volume is equal to each of the respective separate initial volumes, and each gas finally occupies the same volume as it did initially.Planck, M. (1897/1903).

Oxygen equivalent compares the relative amount of oxygen available for respiration at a variable pressure to that available at SATP. As external respiration depends on the exchange of gases due to partial pressures across a semipermeable membrane and normally occurs at SATP, an oxygen equivalent may aid in recognizing and managing variable oxygen availability during procedures such as hyperbaric oxygen therapy or medical air transport. It does so by expressing oxygen concentration as a ratio of the partial pressure of oxygen at a given altitude or pressure to Standard Atmospheric Pressure; rather than as a ratio of the PO2 at a given pressure to the total pressure of the gas mixture. The latter would generally be 0.2095, the atmospheric concentration by volume of O2, although FO2 and Patm vary for extraterrestrials.

SPMDs, or semipermeable membrane devices, are a passive sampling device used to monitor trace levels of organic compounds with a log Kow > 3. SPMDs are an effective way of monitoring the concentrations of chemicals from anthropogenic runoff and pollution in the marine environment because of their ability to detect minuscule levels of chemical. The data collected from a passive sampler is important for examining the amount of chemical in the environment and can therefore be used to formulate other scientific research about the effects of those chemicals on the organisms as well as the environment. Examples of commonly measured chemicals using SPMDs include: PAHs (Polycyclic aromatic hydrocarbons), PCBs (polychlorinated biphenyls), PBDEs (polybrominated diphenyl ethers), dioxins and furans as well as hydrophobic waste-water effluents like fragrances, triclosan and phthalates.

The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non- selectively crossing into the extracellular fluid of the central nervous system where neurons reside. The blood-brain barrier is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane. This system allows the passage of some molecules by passive diffusion, as well as the selective transport of various nutrients, ions, organic anions, and macromolecules such as glucose, water and amino acids that are crucial to neural function. The blood-brain barrier restricts the passage of pathogens, the diffusion of solutes in the blood, and large or hydrophilic molecules into the cerebrospinal fluid, while allowing the diffusion of hydrophobic molecules (O2, CO2, hormones) and small polar molecules.

Reverse osmosis production train, North Cape Coral Reverse Osmosis PlantIn 1977 Cape Coral, Florida became the first municipality in the United States to use the RO process on a large scale with an initial operating capacity of 11.35 million liters (3 million US gal) per day. By 1985, due to the rapid growth in population of Cape Coral, the city had the largest low-pressure reverse-osmosis plant in the world, capable of producing 56.8 million liters (15 million US gal) per day (MGD).2012 Annual Consumer Report on the Quality of Tap Water. City of Cape Coral Formally, reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a semipermeable membrane to a region of low-solute concentration by applying a pressure in excess of the osmotic pressure.

If the solvent outside the bubble is saturated or unsaturated, the partial pressure will be less than in the bubble, and the surface tension will be increasing the internal pressure in direct proportion to surface curvature, providing a pressure gradient to increase diffusion out of the bubble, effectively "squeezing the gas out of the bubble", and the smaller the bubble the faster it will get squeezed out. A gas bubble can only grow at constant pressure if the surrounding solvent is sufficiently supersaturated to overcome the surface tension or if the surface layer provides sufficient reaction to overcome surface tension. Clean bubbles that are sufficiently small will collapse due to surface tension if the supersaturation is low. Bubbles with semipermeable surfaces will either stabilise at a specific radius depending on the pressure, the composition of the surface layer, and the supersaturation, or continue to grow indefinitely, if larger than the critical radius.