Effervescent or carbon tablets are tablets which are designed to dissolve in water, release carbon dioxide. They are products of compression of component ingredients in the form of powders into a dense mass, packaged in blister pack, or with a hermetically sealed package with incorporated desiccant in the cap. To use them, they are dropped into water to make a solution; the powdered ingredients are packaged and sold as effervescent powders or may be granulated and sold as effervescent granules. Powdered ingredients are first granularized before being made into tablets. Effervescent medicinal beverages date back to the late 1800s and arose to mask the taste of bitter waters taken as curatives, during the water cure craze of that era. In the 17th and 18th centuries, scientists began uncovering the chemical make-up and physiological benefits of various salts such as Glauber's salt and Epsom salts; these salts were found in mineral springs, since the Roman Empire, had been used as health spas, where people would go to bathe in, drink, mineral-rich waters for their health.
These developments led to attempts to replicate the salt mixtures found in these occurring mineral waters using off-the-shelf ingredients. Mixing these kinds of salts — carbonates and tartrates — with flavorings like lemon into an effervescent compound with citric or tartaric acid proved popular and set off a craze for the new "fruit salts". Effervescent tablets have been used as products of the pharmaceutical and dietary industries for over two centuries. Vitamin tablets may be sold as effervescent tablets. Alka-selzer is an pain reliever sold as an effervescent powder. There are several categories of active ingredients that may be best administered in the form of effervescent preparations: Those that are difficult to digest or disruptive to the stomach or esophagus Those that are pH–sensitive, such as amino acids and antibiotics; those requiring a large dose. Those that are susceptible to oxygen, or moisture. Other Cleaning tablets may be filled tubs of water; some tablets used for dying eggs for Easter are effervescent.
Baynes, T. S. ed. "Baden", Encyclopædia Britannica, 3, New York: Charles Scribner's Sons, pp. 226–227 Chisholm, Hugh, ed. "Baden", Encyclopædia Britannica, 3, Cambridge University Press, p. 184 "Baden-Baden", Encyclopædia Britannica Online, 2015, retrieved 8 October 2015
The intercostal space is the anatomic space between two ribs. Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it. Several kinds of intercostal muscle intercostal arteries and intercostal veins intercostal lymph nodes intercostal nerves Comprehensive insight in the anatomy of the intercostal spaces is mandatory for everyone who practices medicine. One particular concept is that the neurovascular bundle has a strict order: V-A-N, or vein-artery-nerve, from top to bottom; this neurovascular bundle runs high in the intercostal space, the collateral neurovascular bundle runs just superior to the inferior rib of the space. Invasive procedures such as thoracentesis are thus performed with oblique entry of the instrument, directly above the upper margin of the relevant rib. In reference to the muscles of the thoracic wall, the intercostal nerves and vessels run just behind the internal intercostal muscles: therefore, they are covered on the inside by the parietal pleura, except when they are covered by the innermost intercostal muscles, innermost intercostal membrane, subcostal muscles or the transversus thoracis muscle.
Anatomy figure: 18:04-00 at Human Anatomy Online, SUNY Downstate Medical Center - "Structural organization within an intercostal space." Anatomy photo:18:01-0108 at the SUNY Downstate Medical Center - "Thoracic Wall: The Anterior Thoracic Wall"
Molecular encapsulation in supramolecular chemistry is the confinement of a guest molecule inside the cavity of a supramolecular host molecule. Examples of supramolecular host molecule include endohedral fullerenes. An important implication of encapsulating a molecule at this level is that the guest is prevented from contacting other molecules that it might otherwise react with, thus the encapsulated molecule behaves differently from the way it would when in solution. The guest molecule tends to be unreactive and has much different spectroscopic signatures. Compounds highly unstable in solution, such as arynes or cycloheptatetraene, have been isolated at room temperature when molecularly encapsulated. One of the first examples of encapsulating a structure at the molecular level was demonstrated by Cram and coworkers. Isolation of cyclobutadiene allowed chemists to experimentally confirm one of the most fundamental predictions of the rules of aromaticity. In another example the cage consists of a gallium tetrahedral cluster compound stabilized by 6 bidentate catechol amide ligands residing at the tetrahedron edges.
The guest is a 16 electron and thus reactive ruthenium metallocene with a cyclopentadienyl ligand and a 1,3,7-octatriene ligand. The total charge for this anion is 11 and the counterions are 5 tetramethyl ammonium cations and 6 potassium cations; the ruthenium compound decomposes in water within minutes but encapsulated it survives in water for weeks. Large metalla-assemblies, known as metallaprisms, contain a conformationally flexible cavity that allows them to host a variety of guest molecules; these assemblies have shown promise as agents of drug delivery to cancer cells. An application of encapsulation is controlling reactivity and structure. For instance, excited state reactivity of free 1-phenyl-3-tolyl-2-proponanone yields products A-A, B-B, AB, which result from decarbonylation followed by random recombination of radicals A• and B•. Whereas, the same substrate upon encapsulation reacts to yield the controlled recombination product A-B, rearranged products. Other applications: the encapsulation of filaments of a self-assembling bi-copper complex in polymer nanowires.
According to food chemist Udo Pollmer of the European Institute of Food and Nutrition Sciences in Munich, alcohol can be molecularly encapsulated in cyclodextrines, a sugar derivate. In this way, encapsuled in small capsules, the fluid can be handled as a powder; the cyclodextrines can absorb an estimated 60 percent of their own weight in alcohol. A US patent has been registered for the process as early as 1974. Cryptophane ^ Cram, D. J.. The taming of Cyclobutadiene Angewandte Chemie International Edition Volume 30, Issue 8, Pages 1024 - 1027 1991 Abstract ^ Stabilization of Reactive Organometallic Intermediates Inside a Self-Assembled Nanoscale Host Dorothea Fiedler, Robert G. Bergman, Kenneth N. Raymond Angewandte Chemie International Edition Volume 45, Issue 5, Pages 745 - 748 2006 Abstract Fraser Hof. "Molecular Encapsulation". Angewandte Chemie International Edition. 41: 1488–1508. Doi:10.1002/1521-377341:9<1488::AID-ANIE1488>3.0. CO.
Enteral administration is food or drug administration via the human gastrointestinal tract. This contrasts with parenteral nutrition or drug administration, which occurs from routes outside the GI tract, such as intravenous routes. Enteral administration involves the esophagus and small and large intestines. Methods of administration include oral and rectal. Parenteral administration is via a central vein. In pharmacology, the route of drug administration is important because it affects drug metabolism, drug clearance, thus dosage; the term is from Greek enteros, "intestine". Enteral administration may be divided into three different categories, depending on the entrance point into the GI tract: oral and rectal; the mechanism for drug absorption from the intestine is for most drugs passive transfer, a few exceptions include levodopa and fluorouracil, which are both absorbed through carrier-mediated transport. For passive transfer to occur, the drug has to diffuse through the lipid cell membrane of the epithelial cells lining the inside of the intestines.
The rate at which this happens is determined by two factors: Ionization and lipid solubility. Factors influencing gastrointestinal absorption: Gastrointestinal motility. Splanchnic blood flow. Particle size and formulation. Physicochemical factors. Drugs given by enteral administration may be subjected to significant first pass metabolism, therefore, the amount of drug entering the systemic circulation following administration may vary for different individuals and drugs. Rectal administration is not subject to extensive first pass metabolism. Enteric Feeding tube
OCLC Online Computer Library Center, Incorporated d/b/a OCLC is an American nonprofit cooperative organization "dedicated to the public purposes of furthering access to the world's information and reducing information costs". It was founded in 1967 as the Ohio College Library Center. OCLC and its member libraries cooperatively produce and maintain WorldCat, the largest online public access catalog in the world. OCLC is funded by the fees that libraries have to pay for its services. OCLC maintains the Dewey Decimal Classification system. OCLC began in 1967, as the Ohio College Library Center, through a collaboration of university presidents, vice presidents, library directors who wanted to create a cooperative computerized network for libraries in the state of Ohio; the group first met on July 5, 1967 on the campus of the Ohio State University to sign the articles of incorporation for the nonprofit organization, hired Frederick G. Kilgour, a former Yale University medical school librarian, to design the shared cataloging system.
Kilgour wished to merge the latest information storage and retrieval system of the time, the computer, with the oldest, the library. The plan was to merge the catalogs of Ohio libraries electronically through a computer network and database to streamline operations, control costs, increase efficiency in library management, bringing libraries together to cooperatively keep track of the world's information in order to best serve researchers and scholars; the first library to do online cataloging through OCLC was the Alden Library at Ohio University on August 26, 1971. This was the first online cataloging by any library worldwide. Membership in OCLC is based on use of services and contribution of data. Between 1967 and 1977, OCLC membership was limited to institutions in Ohio, but in 1978, a new governance structure was established that allowed institutions from other states to join. In 2002, the governance structure was again modified to accommodate participation from outside the United States.
As OCLC expanded services in the United States outside Ohio, it relied on establishing strategic partnerships with "networks", organizations that provided training and marketing services. By 2008, there were 15 independent United States regional service providers. OCLC networks played a key role in OCLC governance, with networks electing delegates to serve on the OCLC Members Council. During 2008, OCLC commissioned two studies to look at distribution channels. In early 2009, OCLC negotiated new contracts with the former networks and opened a centralized support center. OCLC provides bibliographic and full-text information to anyone. OCLC and its member libraries cooperatively produce and maintain WorldCat—the OCLC Online Union Catalog, the largest online public access catalog in the world. WorldCat has holding records from private libraries worldwide; the Open WorldCat program, launched in late 2003, exposed a subset of WorldCat records to Web users via popular Internet search and bookselling sites.
In October 2005, the OCLC technical staff began a wiki project, WikiD, allowing readers to add commentary and structured-field information associated with any WorldCat record. WikiD was phased out; the Online Computer Library Center acquired the trademark and copyrights associated with the Dewey Decimal Classification System when it bought Forest Press in 1988. A browser for books with their Dewey Decimal Classifications was available until July 2013; until August 2009, when it was sold to Backstage Library Works, OCLC owned a preservation microfilm and digitization operation called the OCLC Preservation Service Center, with its principal office in Bethlehem, Pennsylvania. The reference management service QuestionPoint provides libraries with tools to communicate with users; this around-the-clock reference service is provided by a cooperative of participating global libraries. Starting in 1971, OCLC produced catalog cards for members alongside its shared online catalog. OCLC commercially sells software, such as CONTENTdm for managing digital collections.
It offers the bibliographic discovery system WorldCat Discovery, which allows for library patrons to use a single search interface to access an institution's catalog, database subscriptions and more. OCLC has been conducting research for the library community for more than 30 years. In accordance with its mission, OCLC makes its research outcomes known through various publications; these publications, including journal articles, reports and presentations, are available through the organization's website. OCLC Publications – Research articles from various journals including Code4Lib Journal, OCLC Research, Reference & User Services Quarterly, College & Research Libraries News, Art Libraries Journal, National Education Association Newsletter; the most recent publications are displayed first, all archived resources, starting in 1970, are available. Membership Reports – A number of significant reports on topics ranging from virtual reference in libraries to perceptions about library funding. Newsletters – Current and archived newsletters for the library and archive community.
Presentations – Presentations from both guest speakers and OCLC research from conferences and other events. The presentations are organized into five categories: Conference presentations, Dewey presentations, Distinguished Seminar Series, Guest presentations, Research staff
A drop or droplet is a small column of liquid, bounded or completely by free surfaces. A drop may form when liquid accumulates at the lower end of a tube or other surface boundary, producing a hanging drop called a pendant drop. Drops may be formed by the condensation of a vapor or by atomization of a larger mass of liquid. Liquid forms drops. A simple way to form a drop is to allow liquid to flow from the lower end of a vertical tube of small diameter; the surface tension of the liquid causes the liquid to hang from the tube. When the drop exceeds a certain size it detaches itself; the falling liquid is a drop held together by surface tension. Some substances that appear to be solid, can be shown to instead be viscous liquids, because they form drops and display droplet behavior. In the famous pitch drop experiments, pitch – a substance somewhat like solid bitumen – is shown to be a liquid in this way. Pitch in a funnel forms droplets, each droplet taking about 10 years to form and break off. In the pendant drop test, a drop of liquid is suspended from the end of a tube by surface tension.
The force due to surface tension is proportional to the length of the boundary between the liquid and the tube, with the proportionality constant denoted γ. Since the length of this boundary is the circumference of the tube, the force due to surface tension is given by F γ = π d γ where d is the tube diameter; the mass m of the drop hanging from the end of the tube can be found by equating the force due to gravity with the component of the surface tension in the vertical direction giving the formula m g = π d γ sin α where α is the angle of contact with the tube, g is the acceleration due to gravity. The limit of this formula, as α goes to 90°, gives the maximum weight of a pendant drop for a liquid with a given surface tension, γ. M g = π d γ This relationship is the basis of a convenient method of measuring surface tension used in the petroleum industry. More sophisticated methods are available to take account of the developing shape of the pendant as the drop grows; these methods are used.
The drop adhesion to a solid can be divided into two categories: lateral adhesion and normal adhesion. Lateral adhesion resembles friction and refers to the force required to slide a drop on the surface, namely the force to detach the drop from its position on the surface only to translate it to another position on the surface. Normal adhesion is the adhesion required to detach a drop from the surface in the normal direction, namely the force to cause the drop to fly off from the surface; the measurement of both adhesion forms can be done with the Centrifugal Adhesion Balance. The CAB uses a combination of centrifugal and gravitational forces to obtain any ratio of lateral and normal forces. For example, it can apply a normal force at zero lateral force for the drop to fly off away from the surface in the normal direction or it can induce a lateral force at zero normal force; the term droplet is a diminutive form of'drop' – and as a guide is used for liquid particles of less than 500 µm diameter.
In spray application, droplets are described by their perceived size whereas the dose is a function of their volume. This increases by a cubic function relative to diameter. A droplet with a diameter of 3 mm has a terminal velocity of 8 m/s. Drops smaller than 1 mm in diameter will attain 95% of their terminal velocity within 2 m, but above this size the distance to get to terminal velocity increases sharply. An example is a drop with a diameter of 2 mm. Due to the different refractive index of water and air and reflection occur on the surfaces of raindrops, leading to rainbow formation; the major source of sound when a droplet hits a liquid surface is the resonance of excited bubbles trapped underwater. These oscillating bubbles are responsible for most liquid sounds, such as running water or splashes, as they consist of many drop-liquid collisions. Reducing the surface tension of a body of liquid makes possible to reduce or prevent noise due to droplets falling into it; this would involve adding detergent or a similar substance to water.
The reduced surface tension reduces the noise from dripping. The classic shape associated with a drop comes from the observation of a droplet clinging to a surface; the shape of a drop falling through a gas is more or less spherical for drops less than 2 mm in diameter. Larger drops tend to be flatter on the bottom part due to the pressure of the gas; as a result, as drops get larger, a concave depression forms which leads to the eventual breakup of the drop. The capillary length is a length scaling factor that relates gravity and surface tension, is directly responsible for
A gel is a solid jelly-like soft material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a dilute cross-linked system, which exhibits no flow when in the steady-state. By weight, gels are liquid, yet they behave like solids due to a three-dimensional cross-linked network within the liquid, it is the crosslinking within the fluid that gives a gel its structure and contributes to the adhesive stick. In this way gels are a dispersion of molecules of a liquid within a solid in which liquid particles are dispersed in the solid medium; the word gel was coined by 19th-century Scottish chemist Thomas Graham by clipping from gelatine. Gels consist of a solid three-dimensional network that spans the volume of a liquid medium and ensnares it through surface tension effects; this internal network structure may result from physical bonds or chemical bonds, as well as crystallites or other junctions that remain intact within the extending fluid. Any fluid can be used as an extender including water and air.
Both by weight and volume, gels are fluid in composition and thus exhibit densities similar to those of their constituent liquids. Edible jelly is a common example of a hydrogel and has the density of water. Polyionic polymers are polymers with an ionic functional group; the ionic charges prevent the formation of coiled polymer chains. This allows them to contribute more to viscosity in their stretched state, because the stretched-out polymer takes up more space; this is the reason gel hardens. See polyelectrolyte for more information. A hydrogel is a network of polymer chains that are hydrophilic, sometimes found as a colloidal gel in which water is the dispersion medium. A three-dimensional solid results from the hydrophilic polymer chains being held together by cross-links; because of the inherent cross-links, the structural integrity of the hydrogel network does not dissolve from the high concentration of water. Hydrogels are absorbent natural or synthetic polymeric networks. Hydrogels possess a degree of flexibility similar to natural tissue, due to their significant water content.
As responsive "smart materials," hydrogels can encapsulate chemical systems which upon stimulation by external factors such as a change of pH may cause specific compounds such as glucose to be liberated to the environment, in most cases by a gel-sol transition to the liquid state. Chemomechanical polymers are also hydrogels, which upon stimulation change their volume and can serve as actuators or sensors; the first appearance of the term'hydrogel' in the literature was in 1894. Common uses for hydrogels include: Scaffolds in tissue engineering; when used as scaffolds, hydrogels may contain human cells to repair tissue. They mimic 3D microenvironment of cells. Hydrogel-coated wells have been used for cell culture Environmentally sensitive hydrogels; these hydrogels have the ability to sense changes of pH, temperature, or the concentration of metabolite and release their load as result of such a change. Sustained-release drug delivery systems Providing absorption and debriding of necrotic and fibrotic tissue Hydrogels that are responsive to specific molecules, such as glucose or antigens, can be used as biosensors, as well as in DDS.
Disposable diapers where they absorb urine, or in sanitary napkins Contact lenses EEG and ECG medical electrodes using hydrogels composed of cross-linked polymers Water gel explosives Rectal drug delivery and diagnosis Encapsulation of quantum dots Breast implants Glue Granules for holding soil moisture in arid areas Dressings for healing of burn or other hard-to-heal wounds. Wound gels are excellent for helping to maintain a moist environment. Reservoirs in topical drug delivery. Materials mimicking animal mucosal tissues to be used for testing mucoadhesive properties of drug delivery systemsCommon ingredients include polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers with an abundance of hydrophilic groups. Natural hydrogel materials are being investigated for tissue engineering. Hydrogels show promise for use in agriculture, as they can release agrochemicals including pesticides and phosphate fertiliser increasing efficacy and reducing runoff, at the same time improve the water retention of drier soils such as sandy loams.
An organogel is a non-crystalline, non-glassy thermoreversible solid material composed of a liquid organic phase entrapped in a three-dimensionally cross-linked network. The liquid can be, for an organic solvent, mineral oil, or vegetable oil; the solubility and particle dimensions of the structurant are important characteristics for the elastic properties and firmness of the organogel. These systems are based on self-assembly of the structurant molecules. Organogels have potential for use in a number of applications, such as in pharmaceuticals, art conservation, food. A xerogel is a solid formed from a gel by drying with unhindered shrinkage. Xerogels retain high porosity and enormous surface area, along with small pore size; when solvent removal occurs under supercritical conditions, the network doe