The ability of a substrate to allow the passage of ELECTRONS.

The heat flow across a surface per unit area per unit time, divided by the negative of the rate of change of temperature with distance in a direction perpendicular to the surface. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

In about 250 species of electric fishes, modified muscle fibers forming disklike multinucleate plates arranged in stacks like batteries in series and embedded in a gelatinous matrix. A large torpedo ray may have half a million plates. Muscles in different parts of the body may be modified, i.e., the trunk and tail in the electric eel, the hyobranchial apparatus in the electric ray, and extrinsic eye muscles in the stargazers. Powerful electric organs emit pulses in brief bursts several times a second. They serve to stun prey and ward off predators. A large torpedo ray can produce of shock of more than 200 volts, capable of stunning a human. (Storer et al., General Zoology, 6th ed, p672)

Fields representing the joint interplay of electric and magnetic forces.

The resistance to the flow of either alternating or direct electrical current.

An order of neotropical electric fish found chiefly in the waters of South America. They continually emit weak electric discharges, which they use in object location and communication. A most popular species of research interest is the electric eel, ELECTROPHORUS electricus.

Use of electric potential or currents to elicit biological responses.

Recording changes in electrical impedance between electrodes placed on opposite sides of a part of the body, as a measure of volume changes in the path of the current. (Stedman, 25th ed)

Injuries caused by electric currents. The concept excludes electric burns (BURNS, ELECTRIC), but includes accidental electrocution and electric shock.

Imaging methods that result in sharp images of objects located on a chosen plane and blurred images located above or below the plane.

A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

A technique of measuring the dielectric properties of materials, which vary over a range of frequencies depending on the physical properties of the material. The technique involves measuring, over a range of frequencies, ELECTRICAL IMPEDANCE and phase shift of an electric field as it passes through the material.

A technique in which electric pulses of intensity in kilovolts per centimeter and of microsecond-to-millisecond duration cause a temporary loss of the semipermeability of CELL MEMBRANES, thus leading to ion leakage, escape of metabolites, and increased uptake by cells of drugs, molecular probes, and DNA.

An arrangement of wires distributing electricity.

Devices that control the supply of electric current for running electrical equipment.

The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.

Plant tissue that carries water up the root and stem. Xylem cell walls derive most of their strength from LIGNIN. The vessels are similar to PHLOEM sieve tubes but lack companion cells and do not have perforated sides and pores.

An allotropic form of carbon that is used in pencils, as a lubricant, and in matches and explosives. It is obtained by mining and its dust can cause lung irritation.

Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.

A genus of the Torpedinidae family consisting of several species. Members of this family have powerful electric organs and are commonly called electric rays.

Characteristics of ELECTRICITY and magnetism such as charged particles and the properties and behavior of charged particles, and other phenomena related to or associated with electromagnetism.

The physical effects involving the presence of electric charges at rest and in motion.

A computer based method of simulating or analyzing the behavior of structures or components.

The loss of water vapor by plants to the atmosphere. It occurs mainly from the leaves through pores (stomata) whose primary function is gas exchange. The water is replaced by a continuous column of water moving upwards from the roots within the xylem vessels. (Concise Dictionary of Biology, 1990)

Magnesium oxide (MgO). An inorganic compound that occurs in nature as the mineral periclase. In aqueous media combines quickly with water to form magnesium hydroxide. It is used as an antacid and mild laxative and has many nonmedicinal uses.

A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.

Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)

Nanometer-sized tubes composed mainly of CARBON. Such nanotubes are used as probes for high-resolution structural and chemical imaging of biomolecules with ATOMIC FORCE MICROSCOPY.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

Computer-based representation of physical systems and phenomena such as chemical processes.

The fluid excreted by the SWEAT GLANDS. It consists of water containing sodium chloride, phosphate, urea, ammonia, and other waste products.

Burns produced by contact with electric current or from a sudden discharge of electricity.

The pressure due to the weight of fluid.

The study, control, and application of the conduction of ELECTRICITY through gases or vacuum, or through semiconducting or conducting materials. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

A treatment modality that uses pulsed electrical currents to permeabilize cell membranes (ELECTROPORATION) and thereby enhance the uptake of chemotherapeutic agents, vaccines, or genes into the body's cells.

The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.

A genus of fish, in the family GYMNOTIFORMES, capable of producing an electric shock that immobilizes fish and other prey. The species Electrophorus electricus is also known as the electric eel, though it is not a true eel.

An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.

The physical characteristics and processes of biological systems.

The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.

The study of MAGNETIC PHENOMENA.

Application of electric current in treatment without the generation of perceptible heat. It includes electric stimulation of nerves or muscles, passage of current into the body, or use of interrupted current of low intensity to raise the threshold of the skin to pain.

An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current.

The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).

The ability of a substrate to retain an electrical charge.

Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.

Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.

Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.

The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.

The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.

Fluids composed mainly of water found within the body.

High molecular weight, insoluble polymers which contain functional groups that are capable of undergoing exchange reactions (ION EXCHANGE) with either cations or anions.

A type of scanning probe microscopy in which a very sharp conducting needle is swept just a few angstroms above the surface of a sample. The tiny tunneling current that flows between the sample and the needle tip is measured, and from this are produced three-dimensional topographs. Due to the poor electron conductivity of most biological samples, thin metal coatings are deposited on the sample.

The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)

Methods of creating machines and devices.

Planet that is the third in order from the sun. It is one of the four inner or terrestrial planets of the SOLAR SYSTEM.

A physical property showing different values in relation to the direction in or along which the measurement is made. The physical property may be with regard to thermal or electric conductivity or light refraction. In crystallography, it describes crystals whose index of refraction varies with the direction of the incident light. It is also called acolotropy and colotropy. The opposite of anisotropy is isotropy wherein the same values characterize the object when measured along axes in all directions.

Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.

Communication between animals involving the giving off by one individual of some chemical or physical signal, that, on being received by another, influences its behavior.

Salts that melt below 100 C. Their low VOLATILIZATION can be an advantage over volatile organic solvents.

The property of blood capillary ENDOTHELIUM that allows for the selective exchange of substances between the blood and surrounding tissues and through membranous barriers such as the BLOOD-AIR BARRIER; BLOOD-AQUEOUS BARRIER; BLOOD-BRAIN BARRIER; BLOOD-NERVE BARRIER; BLOOD-RETINAL BARRIER; and BLOOD-TESTIS BARRIER. Small lipid-soluble molecules such as carbon dioxide and oxygen move freely by diffusion. Water and water-soluble molecules cannot pass through the endothelial walls and are dependent on microscopic pores. These pores show narrow areas (TIGHT JUNCTIONS) which may limit large molecule movement.

The development and use of techniques to study physical phenomena and construct structures in the nanoscale size range or smaller.

Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990)

The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.

The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.

Nanometer-scale composite structures composed of organic molecules intimately incorporated with inorganic molecules. (Glossary of Biotechnology and Nanobiotechology Terms, 4th ed)

That portion of the electromagnetic spectrum from the UHF (ultrahigh frequency) radio waves and extending into the INFRARED RAYS frequencies.

A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

The resistance that a gaseous or liquid system offers to flow when it is subjected to shear stress. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Elements of limited time intervals, contributing to particular results or situations.

The pressure required to prevent the passage of solvent through a semipermeable membrane that separates a pure solvent from a solution of the solvent and solute or that separates different concentrations of a solution. It is proportional to the osmolality of the solution.

Method to determine the occurrence of OVULATION by direct or indirect means. Indirect methods examine the effects of PROGESTERONE on cervical mucus (CERVIX MUCUS), or basal body temperature. Direct ovulation detection, generally used in fertility treatment, involves analyses of circulating hormones in blood and ULTRASONOGRAPHY.

Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)

A layer of the peritoneum which attaches the abdominal viscera to the ABDOMINAL WALL and conveys their blood vessels and nerves.

Nanometer-scale wires made of materials that conduct electricity. They can be coated with molecules such as antibodies that will bind to proteins and other substances.

Characteristics or attributes of the outer boundaries of objects, including molecules.

The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)

The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.

The utilization of an electrical current to measure, analyze, or alter chemicals or chemical reactions in solution, cells, or tissues.

The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

The accumulation of an electric charge on a object

A plant genus of the family ANNONACEAE. Members contain DITERPENES.

A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES.

Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.

A product of hard secondary xylem composed of CELLULOSE, hemicellulose, and LIGNANS, that is under the bark of trees and shrubs. It is used in construction and as a source of CHARCOAL and many other products.

The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)

The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.

Units that convert some other form of energy into electrical energy.

The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.

Removal of tissue by vaporization, abrasion, or destruction. Methods used include heating tissue by hot liquids or microwave thermal heating, freezing (CRYOABLATION), chemical ablation, and photoablation with LASERS.

Materials which have structured components with at least one dimension in the range of 1 to 100 nanometers. These include NANOCOMPOSITES; NANOPARTICLES; NANOTUBES; and NANOWIRES.

A rating of a body of water based on measurable physical, chemical, and biological characteristics.

A process of separating particulate matter from a fluid, such as air or a liquid, by passing the fluid carrier through a medium that will not pass the particulates. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.

The upper part of the human body, or the front or upper part of the body of an animal, typically separated from the rest of the body by a neck, and containing the brain, mouth, and sense organs.

The carbohydrate-rich zone on the cell surface. This zone can be visualized by a variety of stains as well as by its affinity for lectins. Although most of the carbohydrate is attached to intrinsic plasma membrane molecules, the glycocalyx usually also contains both glycoproteins and proteoglycans that have been secreted into the extracellular space and then adsorbed onto the cell surface. (Alberts et al., Molecular Biology of the Cell, 3d ed, p502)

A plant division of GYMNOSPERMS consisting of cone-bearing trees and shrubs.

Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.

Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.

Large natural streams of FRESH WATER formed by converging tributaries and which empty into a body of water (lake or ocean).

The rate dynamics in chemical or physical systems.

The evaluation of incidents involving the loss of function of a device. These evaluations are used for a variety of purposes such as to determine the failure rates, the causes of failures, costs of failures, and the reliability and maintainability of devices.

The functions and activities of living organisms or their parts involved in generating and responding to electrical charges .

Methods utilizing the principles of MICROFLUIDICS for sample handling, reagent mixing, and separation and detection of specific components in fluids.

Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.

An order of fish with 26 families and over 3,000 species. This order includes the families CYPRINIDAE (minnows and CARPS), Cobitidae (loaches), and Catostomidae (suckers).

Water containing no significant amounts of salts, such as water from RIVERS and LAKES.

A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.

The study of the deformation and flow of matter, usually liquids or fluids, and of the plastic flow of solids. The concept covers consistency, dilatancy, liquefaction, resistance to flow, shearing, thixotrophy, and VISCOSITY.

The minute vessels that collect blood from the capillary plexuses and join together to form veins.

Characteristics, properties, and effects of magnetic substances and magnetic fields.

Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.

Microdevices that combine microfluidics technology with electrical and/or mechanical functions for analyzing very small fluid volumes. They consist of microchannels etched into substrates made of silicon, glass, or polymer using processes similar to photolithography. The test fluids in the channels can then interact with different elements such as electrodes, photodetectors, chemical sensors, pumps, and valves.

A plant species of the genus CHRYSANTHEMUM, family ASTERACEAE. The flowers contain PYRETHRINS, cinerolones, and chrysanthemines which are powerful contact insecticides. Most in the old Pyrethrum genus are reclassified to TANACETUM; some to other ASTERACEAE genera.

Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.

Water-soluble low-molecular-weight polymers of acrylic or methacrylic acid that form solid, insoluble products when mixed with specially prepared ZnO powder. The resulting cement adheres to dental enamel and is also used as a luting agent.

The quantity of volume or surface area of CELLS.

An anionic compound that is used as a reagent for determination of potassium, ammonium, rubidium, and cesium ions. It also uncouples oxidative phosphorylation and forms complexes with biological materials, and is used in biological assays.

The common name for all members of the Rajidae family. Skates and rays are members of the same order (Rajiformes). Skates have weak electric organs.

A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.

Ongoing collection, analysis, and interpretation of ecological data that is used to assess changes in the components, processes, and overall condition and functioning of an ECOSYSTEM.

A plant genus in the family PINACEAE, order Pinales, class Pinopsida, division Coniferophyta. They are evergreen, pyramidal trees with whorled branches and thin, scaly bark. Each of the linear, spirally arranged leaves is jointed near the stem on a separate woody base.

A ubiquitous sodium salt that is commonly used to season food.

Induction of a stress reaction in experimental subjects by means of an electrical shock; applies to either convulsive or non-convulsive states.

A technique for growing plants in culture solutions rather than in soil. The roots are immersed in an aerated solution containing the correct proportions of essential mineral salts. (From Concise Dictionary of Biology, 1990)

The flow of water in enviromental bodies of water such as rivers, oceans, water supplies, aquariums, etc. It includes currents, tides, and waves.

A yellow metallic element with the atomic symbol Au, atomic number 79, and atomic weight 197. It is used in jewelry, goldplating of other metals, as currency, and in dental restoration. Many of its clinical applications, such as ANTIRHEUMATIC AGENTS, are in the form of its salts.

Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.

Chemical compounds which pollute the water of rivers, streams, lakes, the sea, reservoirs, or other bodies of water.

Determination of the quantity of a material present in a mixture by measurement of its effect on the electrical conductivity of the mixture. (Webster, 3d ed)

Mercury chloride (HgCl2). A highly toxic compound that volatizes slightly at ordinary temperature and appreciably at 100 degrees C. It is corrosive to mucous membranes and used as a topical antiseptic and disinfectant.

Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behavior of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.

The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.

Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.

Electronic hearing devices typically used for patients with normal outer and middle ear function, but defective inner ear function. In the COCHLEA, the hair cells (HAIR CELLS, VESTIBULAR) may be absent or damaged but there are residual nerve fibers. The device electrically stimulates the COCHLEAR NERVE to create sound sensation.

Substances that dissociate into two or more ions, to some extent, in water. Solutions of electrolytes thus conduct an electric current and can be decomposed by it (ELECTROLYSIS). (Grant & Hackh's Chemical Dictionary, 5th ed)

Nanometer-sized tubes composed of various substances including carbon (CARBON NANOTUBES), boron nitride, or nickel vanadate.

Any of a variety of procedures which use biomolecular probes to measure the presence or concentration of biological molecules, biological structures, microorganisms, etc., by translating a biochemical interaction at the probe surface into a quantifiable physical signal.

Cetyltrimethylammonium compounds that have cationic detergent, antiseptic, and disinfectant activities. They are used in pharmaceuticals, foods, and cosmetics as preservatives; on skin, mucous membranes, etc., as antiseptics or cleansers, and also as emulsifiers. These compounds are toxic when used orally due to neuromuscular blockade.

Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.

Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.

A class of devices combining electrical and mechanical components that have at least one of the dimensions in the micrometer range (between 1 micron and 1 millimeter). They include sensors, actuators, microducts, and micropumps.

Presence of warmth or heat or a temperature notably higher than an accustomed norm.

A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.

Solutions prepared for hemodialysis. The composition of the pre-dialysis solution may be varied in order to determine the effect of solvated metabolites on anoxia, malnutrition, acid-base balance, etc. Of principal interest are the effect of the choice of buffers (e.g., acetate or carbonate), the addition of cations (Na+, K+, Ca2+), and addition of carbohydrates (glucose).

A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.

Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)

Three-dimensional representation to show anatomic structures. Models may be used in place of intact animals or organisms for teaching, practice, and study.

The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.

The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.

The motion of a liquid through a membrane (or plug or capillary) consequent upon the application of an electric field across the membrane. (Oxford Dictionary of Biochemistry and Molecular Biology, 2001)

Physical forces and actions in living things.

Liquid components of living organisms.

Technique whereby the weight of a sample can be followed over a period of time while its temperature is being changed (usually increased at a constant rate).

Materials that have a limited and usually variable electrical conductivity. They are particularly useful for the production of solid-state electronic devices.

A milky, product excreted from the latex canals of a variety of plant species that contain cauotchouc. Latex is composed of 25-35% caoutchouc, 60-75% water, 2% protein, 2% resin, 1.5% sugar & 1% ash. RUBBER is made by the removal of water from latex.(From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed). Hevein proteins are responsible for LATEX HYPERSENSITIVITY. Latexes are used as inert vehicles to carry antibodies or antigens in LATEX FIXATION TESTS.

Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.

Zeolites. A group of crystalline, hydrated alkali-aluminum silicates. They occur naturally in sedimentary and volcanic rocks, altered basalts, ores, and clay deposits. Some 40 known zeolite minerals and a great number of synthetic zeolites are available commercially. (From Merck Index, 11th ed)

An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.

Substances that provide protection against the harmful effects of freezing temperatures.

An electrical current applied to the HEART to terminate a disturbance of its rhythm, ARRHYTHMIAS, CARDIAC. (Stedman, 25th ed)

Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.

Metals that constitute the group 2 (formerly group IIa) of the periodic table.

Relating to the size of solids.

Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).

An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.

A plant genus in the LAURACEAE family. Laurus nobilis L. leaves are known for use in SPICES, having a similar flavor as UMBELLULARIA.

The outer covering of the calvaria. It is composed of several layers: SKIN; subcutaneous connective tissue; the occipitofrontal muscle which includes the tendinous galea aponeurotica; loose connective tissue; and the pericranium (the PERIOSTEUM of the SKULL).

Agents that modify interfacial tension of water; usually substances that have one lipophilic and one hydrophilic group in the molecule; includes soaps, detergents, emulsifiers, dispersing and wetting agents, and several groups of antiseptics.

A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.

A group of peptide antibiotics from BACILLUS brevis. Gramicidin C or S is a cyclic, ten-amino acid polypeptide and gramicidins A, B, D are linear. Gramicidin is one of the two principal components of TYROTHRICIN.

Common name for an order (Anguilliformes) of voracious, elongate, snakelike teleost fishes.

Inorganic compounds that contain tungsten as an integral part of the molecule.

Electrical devices that are composed of semiconductor material, with at least three connections to an external electronic circuit. They are used to amplify electrical signals, detect signals, or as switches.

Stable elementary particles having the smallest known negative charge, present in all elements; also called negatrons. Positively charged electrons are called positrons. The numbers, energies and arrangement of electrons around atomic nuclei determine the chemical identities of elements. Beams of electrons are called CATHODE RAYS.

Computer systems utilized as adjuncts in the treatment of disease.

Substances released by PLANTS such as PLANT GUMS and PLANT RESINS.

Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.

The research and development of ELECTRICAL EQUIPMENT AND SUPPLIES for such medical applications as diagnosis, therapy, research, anesthesia control, cardiac control, and surgery. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

A dye used as a reagent in the determination of vitamin C.

The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.

Application of computer programs designed to assist the physician in solving a diagnostic problem.

The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.

Procedures using an electrically heated wire or scalpel to treat hemorrhage (e.g., bleeding ulcers) and to ablate tumors, mucosal lesions, and refractory arrhythmias. It is different from ELECTROSURGERY which is used more for cutting tissue than destroying and in which the patient is part of the electric circuit.

Any of the numerous types of clay which contain varying proportions of Al2O3 and SiO2. They are made synthetically by heating aluminum fluoride at 1000-2000 degrees C with silica and water vapor. (From Hawley's Condensed Chemical Dictionary, 11th ed)

The generic term for salts derived from silica or the silicic acids. They contain silicon, oxygen, and one or more metals, and may contain hydrogen. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th Ed)

A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.

Treatment process involving the injection of fluid into an organ or tissue.

Substances produced from the reaction between acids and bases; compounds consisting of a metal (positive) and nonmetal (negative) radical. (Grant & Hackh's Chemical Dictionary, 5th ed)

A plant genus of the family ACERACEAE, best known for trees with palmately lobed leaves.

The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Cellular processes, properties, and characteristics.

The branch of physics that deals with sound and sound waves. In medicine it is often applied in procedures in speech and hearing studies. With regard to the environment, it refers to the characteristics of a room, auditorium, theatre, building, etc. that determines the audibility or fidelity of sounds in it. (From Random House Unabridged Dictionary, 2d ed)

That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.

Coating with a metal or alloy by electrolysis.

An insecticide and herbicide that has also been used as a wood preservative. Pentachlorphenol is a widespread environmental pollutant. Both chronic and acute pentachlorophenol poisoning are medical concerns. The range of its biological actions is still being actively explored, but it is clearly a potent enzyme inhibitor and has been used as such as an experimental tool.

The inner layer of CHOROID, also called the lamina basalis choroideae, located adjacent to the RETINAL PIGMENT EPITHELIUM; (RPE) of the EYE. It is a membrane composed of the basement membranes of the choriocapillaris ENDOTHELIUM and that of the RPE. The membrane stops at the OPTIC NERVE, as does the RPE.

The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.

The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.

Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.