Hydrogen-Ion Concentration: 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)Gastric Acidity Determination: Gastric analysis for determination of free acid or total acid.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Acid-Base Equilibrium: The balance between acids and bases in the BODY FLUIDS. The pH (HYDROGEN-ION CONCENTRATION) of the arterial BLOOD provides an index for the total body acid-base balance.Hydrogen: The first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic weight [1.00784; 1.00811]. It exists, under normal conditions, as a colorless, odorless, tasteless, diatomic gas. Hydrogen ions are PROTONS. Besides the common H1 isotope, hydrogen exists as the stable isotope DEUTERIUM and the unstable, radioactive isotope TRITIUM.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Bicarbonates: Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the pH of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity.Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Potentiometry: Solution titration in which the end point is read from the electrode-potential variations with the concentrations of potential determining ions. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Oxidation-Reduction: A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Hydrogen Bonding: A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.Hydrogen Peroxide: A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.Ferredoxins: Iron-containing proteins that transfer electrons, usually at a low potential, to flavoproteins; the iron is not present as in heme. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Hydrogen Sulfide: A flammable, poisonous gas with a characteristic odor of rotten eggs. It is used in the manufacture of chemicals, in metallurgy, and as an analytical reagent. (From Merck Index, 11th ed)Electron Spin Resonance Spectroscopy: A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.Electrodes, Implanted: Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.Spectrophotometry: The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.Potassium: 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.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Protons: 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.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Buffers: A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.Ion-Selective Electrodes: Electrodes which can be used to measure the concentration of particular ions in cells, tissues, or solutions.Acidosis: A pathologic condition of acid accumulation or depletion of base in the body. The two main types are RESPIRATORY ACIDOSIS and metabolic acidosis, due to metabolic acid build up.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Ions: 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.Kinetics: The rate dynamics in chemical or physical systems.Ion Channels: 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.Hydrochloric Acid: A strong corrosive acid that is commonly used as a laboratory reagent. It is formed by dissolving hydrogen chloride in water. GASTRIC ACID is the hydrochloric acid component of GASTRIC JUICE.Osmolar Concentration: 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.Membrane Potentials: 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).Acidosis, Respiratory: Respiratory retention of carbon dioxide. It may be chronic or acute.Gastric Juice: The liquid secretion of the stomach mucosa consisting of hydrochloric acid (GASTRIC ACID); PEPSINOGENS; INTRINSIC FACTOR; GASTRIN; MUCUS; and the bicarbonate ion (BICARBONATES). (From Best & Taylor's Physiological Basis of Medical Practice, 12th ed, p651)Magnesium: A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.Water: 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)Acetazolamide: One of the CARBONIC ANHYDRASE INHIBITORS that is sometimes effective against absence seizures. It is sometimes useful also as an adjunct in the treatment of tonic-clonic, myoclonic, and atonic seizures, particularly in women whose seizures occur or are exacerbated at specific times in the menstrual cycle. However, its usefulness is transient often because of rapid development of tolerance. Its antiepileptic effect may be due to its inhibitory effect on brain carbonic anhydrase, which leads to an increased transneuronal chloride gradient, increased chloride current, and increased inhibition. (From Smith and Reynard, Textbook of Pharmacology, 1991, p337)Partial Pressure: The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Acidosis, Renal Tubular: A group of genetic disorders of the KIDNEY TUBULES characterized by the accumulation of metabolically produced acids with elevated plasma chloride, hyperchloremic metabolic ACIDOSIS. Defective renal acidification of URINE (proximal tubules) or low renal acid excretion (distal tubules) can lead to complications such as HYPOKALEMIA, hypercalcinuria with NEPHROLITHIASIS and NEPHROCALCINOSIS, and RICKETS.Ion Transport: 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.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Alkalosis, Respiratory: A state due to excess loss of carbon dioxide from the body. (Dorland, 27th ed)Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Biological Transport, Active: The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.Ammonium Chloride: An acidifying agent that has expectorant and diuretic effects. Also used in etching and batteries and as a flux in electroplating.Electrophysiology: 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.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Microelectrodes: 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)Extracellular Space: 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.Oxygen: An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.Temperature: 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.Secretory Rate: The amount of a substance secreted by cells or by a specific organ or organism over a given period of time; usually applies to those substances which are formed by glandular tissues and are released by them into biological fluids, e.g., secretory rate of corticosteroids by the adrenal cortex, secretory rate of gastric acid by the gastric mucosa.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Electrochemical Techniques: The utilization of an electrical current to measure, analyze, or alter chemicals or chemical reactions in solution, cells, or tissues.Hydrogen Cyanide: Hydrogen cyanide (HCN); A toxic liquid or colorless gas. It is found in the smoke of various tobacco products and released by combustion of nitrogen-containing organic materials.Sodium Chloride: A ubiquitous sodium salt that is commonly used to season food.Potassium Chloride: A white crystal or crystalline powder used in BUFFERS; FERTILIZERS; and EXPLOSIVES. It can be used to replenish ELECTROLYTES and restore WATER-ELECTROLYTE BALANCE in treating HYPOKALEMIA.TurtlesHelix (Snails): A genus of chiefly Eurasian and African land snails including the principal edible snails as well as several pests of cultivated plants.Models, Biological: 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.Metals: Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed)Sodium Bicarbonate: A white, crystalline powder that is commonly used as a pH buffering agent, an electrolyte replenisher, systemic alkalizer and in topical cleansing solutions.Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Phosphates: Inorganic salts of phosphoric acid.Cations, Monovalent: Positively charged atoms, radicals or group of atoms with a valence of plus 1, which travel to the cathode or negative pole during electrolysis.Ion Channel Gating: The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.Acids: Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. (Grant & Hackh's Chemical Dictionary, 5th ed)Cations: Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.Thermodynamics: A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Electric Stimulation: Use of electric potential or currents to elicit biological responses.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Solutions: 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)Catalase: An oxidoreductase that catalyzes the conversion of HYDROGEN PEROXIDE to water and oxygen. It is present in many animal cells. A deficiency of this enzyme results in ACATALASIA.Oxidants: Electron-accepting molecules in chemical reactions in which electrons are transferred from one molecule to another (OXIDATION-REDUCTION).Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Cobalt: A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.Deuterium Exchange Measurement: A research technique to measure solvent exposed regions of molecules that is used to provide insight about PROTEIN CONFORMATION.Lactates: Salts or esters of LACTIC ACID containing the general formula CH3CHOHCOOR.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Hypercapnia: A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood.Sodium-Hydrogen Antiporter: A plasma membrane exchange glycoprotein transporter that functions in intracellular pH regulation, cell volume regulation, and cellular response to many different hormones and mitogens.Biosensing Techniques: 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.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Cations, Divalent: Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Amiloride: A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)Catalysis: The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.Mathematics: The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Graphite: 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.Gastric Mucosa: Lining of the STOMACH, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. The surface cells produce MUCUS that protects the stomach from attack by digestive acid and enzymes. When the epithelium invaginates into the LAMINA PROPRIA at various region of the stomach (CARDIA; GASTRIC FUNDUS; and PYLORUS), different tubular gastric glands are formed. These glands consist of cells that secrete mucus, enzymes, HYDROCHLORIC ACID, or hormones.Sulfates: Inorganic salts of sulfuric acid.Fluorocarbon PolymersIonophores: Chemical agents that increase the permeability of biological or artificial lipid membranes to specific ions. Most ionophores are relatively small organic molecules that act as mobile carriers within membranes or coalesce to form ion permeable channels across membranes. Many are antibiotics, and many act as uncoupling agents by short-circuiting the proton gradient across mitochondrial membranes.Aequorin: A photoprotein isolated from the bioluminescent jellyfish Aequorea. It emits visible light by an intramolecular reaction when a trace amount of calcium ion is added. The light-emitting moiety in the bioluminescence reaction is believed to be 2-amino-3-benzyl-5-(p-hydroxyphenyl)pyrazine (AF-350).Dinitrophenols: Organic compounds that contain two nitro groups attached to a phenol.Membranes, Artificial: 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.Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Manganese: A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)Glucose Oxidase: An enzyme of the oxidoreductase class that catalyzes the conversion of beta-D-glucose and oxygen to D-glucono-1,5-lactone and peroxide. It is a flavoprotein, highly specific for beta-D-glucose. The enzyme is produced by Penicillium notatum and other fungi and has antibacterial activity in the presence of glucose and oxygen. It is used to estimate glucose concentration in blood or urine samples through the formation of colored dyes by the hydrogen peroxide produced in the reaction. (From Enzyme Nomenclature, 1992) EC 1.1.3.4.Quaternary Ammonium Compounds: 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.Biological Transport: 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.Equipment Design: Methods of creating machines and devices.Static Electricity: The accumulation of an electric charge on a objectCopper: A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.Pentagastrin: A synthetic pentapeptide that has effects like gastrin when given parenterally. It stimulates the secretion of gastric acid, pepsin, and intrinsic factor, and has been used as a diagnostic aid.Zinc: A metallic element of atomic number 30 and atomic weight 65.38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with ANEMIA, short stature, HYPOGONADISM, impaired WOUND HEALING, and geophagia. It is known by the symbol Zn.Cystathionine gamma-Lyase: A multifunctional pyridoxal phosphate enzyme. In the final step in the biosynthesis of cysteine it catalyzes the cleavage of cystathionine to yield cysteine, ammonia, and 2-ketobutyrate. EC 4.4.1.1.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Enzymes: Biological molecules that possess catalytic activity. They may occur naturally or be synthetically created. Enzymes are usually proteins, however CATALYTIC RNA and CATALYTIC DNA molecules have also been identified.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Gastric Acid: Hydrochloric acid present in GASTRIC JUICE.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Gramicidin: 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.Nucleic Acid Conformation: The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.Hydrogenase: An enzyme found in bacteria. It catalyzes the reduction of FERREDOXIN and other substances in the presence of molecular hydrogen and is involved in the electron transport of bacterial photosynthesis.Gold: 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.Chromium: A trace element that plays a role in glucose metabolism. It has the atomic symbol Cr, atomic number 24, and atomic weight 52. According to the Fourth Annual Report on Carcinogens (NTP85-002,1985), chromium and some of its compounds have been listed as known carcinogens.Enzymes, Immobilized: Enzymes which are immobilized on or in a variety of water-soluble or water-insoluble matrices with little or no loss of their catalytic activity. Since they can be reused continuously, immobilized enzymes have found wide application in the industrial, medical and research fields.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Endolymph: The lymph fluid found in the membranous labyrinth of the ear. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Electrolytes: 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)Depression, Chemical: The decrease in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Absorption: The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.Nickel: A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Chelating Agents: Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.PeroxidasesLasalocid: Cationic ionophore antibiotic obtained from Streptomyces lasaliensis that, among other effects, dissociates the calcium fluxes in muscle fibers. It is used as a coccidiostat, especially in poultry.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Conductometry: 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)Strontium: An element of the alkaline earth family of metals. It has the atomic symbol Sr, atomic number 38, and atomic weight 87.62.Body Fluids: Liquid components of living organisms.Osmosis: Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.Calibration: Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output.Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Calcium Chloride: A salt used to replenish calcium levels, as an acid-producing diuretic, and as an antidote for magnesium poisoning.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Gases: The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)Urinary Bladder: A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Permeability: Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.Physicochemical Phenomena: The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.Anura: An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.Intracellular Fluid: The fluid inside CELLS.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Sulfides: Chemical groups containing the covalent sulfur bonds -S-. The sulfur atom can be bound to inorganic or organic moieties.Chemistry, Physical: The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.Electric Impedance: The resistance to the flow of either alternating or direct electrical current.Potassium Isotopes: Stable potassium atoms that have the same atomic number as the element potassium, but differ in atomic weight. K-41 is a stable potassium isotope.Egtazic Acid: A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.Muscles: Contractile tissue that produces movement in animals.Air Ionization: The dissociation of molecules in the air into positive and negative ions under the influence of an electric field.Electrolysis: Destruction by passage of a galvanic electric current, as in disintegration of a chemical compound in solution.Heavy Ions: Positively-charged atomic nuclei that have been stripped of their electrons. These particles have one or more units of electric charge and a mass exceeding that of the Helium-4 nucleus (alpha particle).Adenosine Triphosphate: An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.Electricity: The physical effects involving the presence of electric charges at rest and in motion.Ouabain: A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Cochlear Implants: 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.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Bacterial Proteins: Proteins found in any species of bacterium.Salts: 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)Biophysical Phenomena: The physical characteristics and processes of biological systems.Molecular Conformation: The characteristic three-dimensional shape of a molecule.Cochlear Implantation: Surgical insertion of an electronic hearing device (COCHLEAR IMPLANTS) with electrodes to the COCHLEAR NERVE in the inner ear to create sound sensation in patients with residual nerve fibers.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Fura-2: A fluorescent calcium chelating agent which is used to study intracellular calcium in tissues.Hot Temperature: Presence of warmth or heat or a temperature notably higher than an accustomed norm.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Iron: A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.Salinity: Degree of saltiness, which is largely the OSMOLAR CONCENTRATION of SODIUM CHLORIDE plus any other SALTS present. It is an ecological factor of considerable importance, influencing the types of organisms that live in an ENVIRONMENT.Ammonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Cadmium: An element with atomic symbol Cd, atomic number 48, and atomic weight 114. It is a metal and ingestion will lead to CADMIUM POISONING.Carbonates: Salts or ions of the theoretical carbonic acid, containing the radical CO2(3-). Carbonates are readily decomposed by acids. The carbonates of the alkali metals are water-soluble; all others are insoluble. (From Grant & Hackh's Chemical Dictionary, 5th ed)Free Radicals: Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.Diffusion: 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.Barium: An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.Lithium: An element in the alkali metals family. It has the atomic symbol Li, atomic number 3, and atomic weight [6.938; 6.997]. Salts of lithium are used in treating BIPOLAR DISORDER.DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).Protein Structure, Secondary: The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.Hydroxyl Radical: The univalent radical OH. Hydroxyl radical is a potent oxidizing agent.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Cesium: A member of the alkali metals. It has an atomic symbol Cs, atomic number 50, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.Anions: Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Chemistry: A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Decapodiformes: A superorder of CEPHALOPODS comprised of squid, cuttlefish, and their relatives. Their distinguishing feature is the modification of their fourth pair of arms into tentacles, resulting in 10 limbs.Reactive Oxygen Species: Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of signal transduction and gene expression, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Chemical Phenomena: The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.
McClendon J. F. New hydrogen electrodes and rapid methods of determining hydrogen ion concentrations. - Amer. J. Physoil., 1915 ...
1924 The Electrical Charge on a Clay Colloid as Influenced by Hydrogen-Ion Concentration and by Different Salts. With W. C. ... 1916 Acidity and Adsorption in Soils as Measured by Hydrogen Electrode. With L. T. Sharp. J. Agr. Res., 7:3. 1917 The Effect of ... Hydrogen-Ion Effects and the Accumulation of Salt by Barley Roots as Influenced by Metabolism. With T. C. Broyer. Am. J. Bot., ... Hydrogen and Hydroxyl Ion Concentration on the Growth of Barley Seedlings. Soil Sci., 3(6) 547-560. 1918 Relation of Carbon ...
McClendon J. F. New hydrogen electrodes and rapid methods of determining hydrogen ion concentrations. Amer. J. Physiol., 1915, ... The hydrogen ion concentrations of the contents of the small intestine. J. of Biological Chemistry, Feb 19, 1918. XXXIV, No 1. ... McClendon J. F. A direct reading potenciometer for measuring hydrogen ion concentration. Amer. J. Physiol., 1915, 38, 2, 186. ... stomachs and duodenums of adults and infants plotted with the acid of imported methods of measuring hydrogen ion concentration ...
The concentration, or activity, of the hydrogen ion is monitored by means of a glass electrode. The data set used for the ... In water the concentration of hydroxide is related to the concentration of hydrogen ions by the self-ionization constant, Kw. ... The two equilibria are H + L ⇌ HL M + L ⇌ ML Hence by following the hydrogen ion concentration during a titration of a mixture ... method was the use of the then recently developed glass electrode and pH meter to determine the concentration of hydrogen ions ...
Chemist Glen Joseph at Sunkist was attempting to measure the hydrogen-ion concentration in lemon juice electrochemically, but ... sulfur dioxide damaged hydrogen electrodes, and non-reactive glass electrodes produced weak signals and were fragile. Joseph ... The glass electrode used to measure pH was placed in a grid circuit in the vacuum tube, producing an amplified signal which ... The earliest meter had a design glitch, in that the pH readings changed with the depth of immersion of the electrodes, but ...
... and the activity of hydrogen ions in the solution is unity. The activity of hydrogen ions is their effective concentration, ... electrode potentials Reversible hydrogen electrode Palladium-hydrogen electrode Reference electrode Dynamic hydrogen electrode ... Potentials of any other electrodes are compared with that of the standard hydrogen electrode at the same temperature. Hydrogen ... The scheme of the standard hydrogen electrode: platinized platinum electrode hydrogen blow solution of the acid with activity ...
The hydrogen ion concentration is therefore not 1, but corresponds to that of the electrolyte solution; in this way we can ... Dynamic hydrogen electrode Palladium-hydrogen electrode Cai, Yu; Anderson, Alfred B. (2004). "The reversible hydrogen electrode ... A reversible hydrogen electrode (RHE) is a reference electrode, more specifically a subtype of the standard hydrogen electrodes ... The reversible hydrogen electrode is a fairly practical and reproducible electrode "standard." The term refers to a hydrogen ...
The quinhydrone electrode is a type of redox electrode which can be used to measure the hydrogen ion concentration (pH) of a ... Because the electrode half-reaction involves hydrogen ions, the electrode potential depends on the activity of hydrogen ions. ... the hydrogen electrode, the antimony - antimony oxide electrode, and the ion-sensitive field effect transistor ISFET electrode ... and also the hydrogen ion concentration. The electrode half-reaction is: Hydroquinone ↔ Quinone + 2H+ +2e− ...
If the electrode is calibrated in terms of known hydrogen ion concentrations it would be better to write p[H] rather than pH, ... In aqueous solution the concentration of the hydroxide ion is related to the concentration of the hydrogen ion by K W = [ H ... pH is defined in terms of the activity of the hydrogen ion pH = −log10 {H+} In the approximation of ideal behaviour, activity ... H3O+ the concentration of water may be taken as being constant and the formation of the hydronium ion is implicit. AH ⇋ {\ ...
... it is possible to measure the concentration of hydrogen ions directly, if the electrode is calibrated in terms of hydrogen ion ... The reference electrode may be a silver chloride electrode or a calomel electrode. The hydrogen-ion selective electrode is a ... The concentration of hydroxide ions in water is related to the concentration of hydrogen ions by [ O H − ] = K W [ H + ] {\ ... Since addition of hydroxide reduces the hydrogen ion concentration, and the hydroxide ion concentration is constrained by the ...
Potassium ions usually cause less error than sodium ions. Acidic error range - at very high concentration of hydrogen ions (low ... The pH electrode is an example of a glass electrode that is sensitive to hydrogen ions. Glass electrodes play an important part ... A glass electrode is a type of ion-selective electrode made of a doped glass membrane that is sensitive to a specific ion. The ... Potentiometry Ion-selective electrodes ISFET pH electrode Chalcogenide glass Quinhydrone electrode Bates, Roger G. (1954). " ...
If the electrode is calibrated in terms of known hydrogen ion concentrations it would be better to write p[H] rather than pH, ... In aqueous solution the concentration of the hydroxide ion is related to the concentration of the hydrogen ion by ... The concentration quotient K. c. {\displaystyle K^{c}}. has the dimension 1/concentration, but the thermodynamic equilibrium ... Replace each concentration term [. X. ]. {\displaystyle [X]}. by the dimensionless quotient [. X. ]. [. X. 0. ]. {\displaystyle ...
... chloride electrode on the activity or effective concentration of chloride-ions: E = E 0 − R T F ln ⁡ a Cl − {\displaystyle E=E ... Reference electrode Saturated calomel electrode Standard hydrogen electrode Copper-copper(II) sulfate electrode Cathodic ... The potential of a silver:silver chloride reference electrode with respect to the standard hydrogen electrode depends on the ... 0}-{\frac {RT}{F}}\ln a_{\ce {Cl-}}} The standard electrode potential E0 against standard hydrogen electrode (SHE) is 0.230V ± ...
... molar concentration) of hydrogen or hydronium ion, and [OH−] is the concentration of hydroxide ion. When the equilibrium ... Water portal Chemical equilibrium Acid-base reaction Standard hydrogen electrode "Release on the Ionization Constant of H2O" ( ... If an impurity is an acid or base, this will affect the concentrations of hydronium ion and hydroxide ion. Water samples that ... the hydrogen nucleus of the hydronium ion travels along water molecules by the Grotthuss mechanism and a change in the hydrogen ...
... sulfate electrode on the activity or concentration copper-ions: E = 0.337 + R T 2 F ln ⁡ a C u 2 + {\displaystyle E=0.337+{\ ... The potential of a copper copper sulfate electrode is +0.314 volt with respect to the standard hydrogen electrode.[citation ... The copper-copper(II) sulfate electrode is a reference electrode of the first kind, based on the redox reaction with ... It is used for measuring electrode potential and is the most commonly used reference electrode for testing cathodic protection ...
A cation with a greater standard electrode potential than a hydrogen ion will be reduced in its stead, and no hydrogen gas will ... This can cause a concentration overpotential at both electrodes. Pure water is a fairly good insulator since it has a low ... Oxygen will collect at the positively charged electrode (anode) and hydrogen will collect at the negatively charged electrode ( ... With the correct electrodes and correct electrolyte, such as baking soda (sodium bicarbonate), hydrogen and oxygen gases will ...
This development allowed for testing the solubility of salts and hydrogen ion concentration, as well as acid/base and redox ... Conductometry was further improved with the development of the glass electrode, which began in 1909. Conductometric titration ... are associated with the changing concentrations of the two most highly conducting ions-the hydrogen and hydroxyl ions. The ... For each amount of NaOH added equivalent amount of hydrogen ions is removed. Effectively, the mobile H+ cation is replaced by ...
... molecular hydrogen. Two phases can coexist in palladium when hydrogen is absorbed: alpha-phase at hydrogen concentration less ... of a palladium electrode in equilibrium with H3O+ ions in solution parallels the behaviour of palladium with molecular hydrogen ... Dynamic hydrogen electrode Reversible hydrogen electrode Operation principle of Pd/H2 reference electrode A palladium-hydrogen ... The palladium-hydrogen electrode (abbreviation: Pd/H2) is one of the common reference electrodes used in electrochemical study ...
The standard reduction potential is defined relative to a standard hydrogen electrode (SHE) reference electrode, which is ... Just as the transfer of hydrogen ions between chemical species determines the pH of an aqueous solution, the transfer of ... In fact, it is possible to define pE, the negative logarithm of electron concentration (-log[e]) in a solution, which will be ... See also: Standard hydrogen electrode. The standard reduction potential (. E. 0. {\displaystyle E_{0}}. ) is measured under ...
Alkali anion exchange membrane Concentration cell Electrode potential Glossary of fuel cell terms Ion transport number Liquid ... GDEs are used in fuel cells, where oxygen and hydrogen react at the gas diffusion electrodes, to form water, while converting ... At first solid electrodes were used in the Grove cell, Francis Thomas Bacon was the first to use gas diffusion electrodes for ... Gas diffusion electrodes (GDE) are electrodes with a conjunction of a solid, liquid and gaseous interface, and an electrical ...
Potentiometry The most widely used electrode is the glass electrode, which is selective for the hydrogen ion. This is suitable ... A free concentration [A] or activity {A} of a species A is measured by means of an ion selective electrode such as the glass ... When the pH (or equivalent e.m.f., E).is measured, the free concentration of hydrogen ions, [H], is obtained from the measured ... Constant-boiling hydrochloric acid may also be used as a primary standard for hydrogen ion concentration. It is assumed that ...
After the plasma stream leaves the arc region, the ions recombine quickly, leaving the hot gas having high concentrations of ... Otherwise, the high voltage electrodes may spark to the ground. Depending on the polarity of the high voltage electrode one ... ions, atoms and molecules - which then would produce large quantities of chemical compounds of hydrogen, nitrogen and oxygen, ... Deposition of functional chemical groups. Short-lived chemical species, produced within the plasma volume, as well as the ions ...
Today, the concentration of potassium is determined by a number of methods such as ion-selective electrodes, flame photometry, ... Mukund P. Sibi,"Hydrogen Hexachloroplatinate(IV)" Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons. doi: ... Determinations were done in 85% (v/v) alcohol solutions with excess platinate ions, and the precipitated product was weighed. ... Rudnick, Paul; Cooke, R. D. (1917). "The Preparation of Hydrochloroplatinic Acid by means of Hydrogen Peroxide". J. Am. Chem. ...
Due to the high concentration of chloride ions, the concentration of mercury ions ( [ Hg 2 2 + ] {\displaystyle {\ce {[Hg2^2+ ... Cyclic voltammetry information Standard Hydrogen Electrode Table of standard electrode potentials Reference electrode Sawyer, ... In both electrodes, the activity of the metal ion is fixed by the solubility of the metal salt. The calomel electrode contains ... The electrode is normally linked via a porous frit to the solution in which the other electrode is immersed. This porous frit ...
... the analytical concentration of the hydrogen ion is obtained from the initial concentration of acid, Ci and the amount of ... E0 is a standard electrode potential, s is the slope, ideally equal to RT/nF, and {H+} is the activity of the hydrogen ion. The ... depending on whether the electrode is calibrated in millivolts or pH. For convenience the concentration, [H+], is used in place ... Other types of concentration measures, such as spectrophotometric absorbances or NMR chemical shifts, can in principle be ...
When some strong acid is added to an equilibrium mixture of the weak acid and its conjugate base, the equilibrium is shifted to the left, in accordance with Le Châtelier's principle. Because of this, the hydrogen ion concentration increases by less than the amount expected for the quantity of strong acid added. Similarly, if strong alkali is added to the mixture the hydrogen ion concentration decreases by less than the amount expected for the quantity of alkali added. The effect is illustrated by the simulated titration of a weak acid with pKa = 4.7. The relative concentration of undissociated acid is shown in blue and of its conjugate base in red. The pH changes relatively slowly in the buffer region, pH = pKa ± 1, centered at pH = 4.7 where [HA] = [A−]. The hydrogen ion ...
Most acidophile organisms have evolved extremely efficient mechanisms to pump protons out of the intracellular space in order to keep the cytoplasm at or near neutral pH. Therefore, intracellular proteins do not need to develop acid stability through evolution. However, other acidophiles, such as Acetobacter aceti, have an acidified cytoplasm which forces nearly all proteins in the genome to evolve acid stability.[7] For this reason, Acetobacter aceti has become a valuable resource for understanding the mechanisms by which proteins can attain acid stability. Studies of proteins adapted to low pH have revealed a few general mechanisms by which proteins can achieve acid stability. In most acid stable proteins (such as pepsin and the soxF protein from Sulfolobus acidocaldarius), there is an overabundance of acidic residues which minimizes low pH destabilization induced by a buildup of positive charge. Other mechanisms include minimization of solvent ...
A calpain (/ˈkælpeɪn/; EC 3.4.22.52, EC 3.4.22.53) is a protein belonging to the family of calcium-dependent, non-lysosomal cysteine proteases (proteolytic enzymes) expressed ubiquitously in mammals and many other organisms. Calpains constitute the C2 family of protease clan CA in the MEROPS database. The calpain proteolytic system includes the calpain proteases, the small regulatory subunit CAPNS1, also known as CAPN4, and the endogenous calpain-specific inhibitor, calpastatin. The history of calpain originates in 1964, when calcium-dependent proteolytic activities caused by a "calcium-activated neutral protease" (CANP) were detected in brain, lens of the eye and other tissues. In the late 1960s the enzymes were isolated and characterised independently in both rat brain and skeletal muscle. These activities were caused by an intracellular cysteine protease not associated with the lysosome and having an optimum activity at neutral pH, which clearly distinguished it from the cathepsin family ...
Most NONOates are stable in alkaline solution above pH 8.0 (e. g. 10 mM NaOH) and can be stored at −20 °C in this way for the short term. To generate NO from NONOates, the pH is lowered accordingly. Typically, a dilution of the stock NONOate solution is made in a phosphate buffer (pH 7.4; tris buffers can also be used) and incubated at room temperature for the desired time to allow NO to accumulate in solution. This is often visible as bubbles at high NONOate concentrations. Incubation time is important, since the different NONOates have different half-lives (t½) in phosphate buffer at pH 7.4. For example, the half-life of MAHMA NONOate under these conditions is ~3.5 minutes, whilst the t½ of DPTA NONOate is 300 minutes. This is often useful in biological systems, where a combination of different NONOates can be used to give a sustained release of nitric oxide. At pH 5.0, ...
The experimental determination of pKa values is commonly performed by means of titrations, in a medium of high ionic strength and at constant temperature.[54] A typical procedure would be as follows. A solution of the compound in the medium is acidified with a strong acid to the point where the compound is fully protonated. The solution is then titrated with a strong base until all the protons have been removed. At each point in the titration pH is measured using a glass electrode and a pH meter. The equilibrium constants are found by fitting calculated pH values to the observed values, using the method of least squares.[55]. The total volume of added strong base should be small compared to the initial volume of titrand solution in order to keep the ionic strength nearly constant. This will ensure that pKa remains invariant during the ...
NADH is oxidized into NAD+, H+ ions, and electrons by an enzyme. FADH2 is also oxidized into H+ ions, electrons, and FAD. As those electrons travel farther through the electron transport chain in the inner membrane, energy is gradually released and used to pump the hydrogen ions from the splitting of NADH and FADH2 into the space between the inner membrane and the outer membrane (called the intermembrane space), creating an electrochemical gradient.. This electrochemical gradient creates potential energy (see potential energy § chemical potential energy) across the inner mitochondrial membrane known as the proton-motive force. As a result, chemiosmosis occurs, and the enzyme ATP synthase produces ATP from ADP and a phosphate group. This harnesses the potential energy from the concentration gradient formed by the amount of H+ ions. H+ ions passively pass into the ...
Comparatively simple devices are often used to apply counterions of increasing gradient to a chromatography column. Counterions such as copper (II) are chosen most often for effectively separating peptides and amino acids through complex formation.[19] A simple device can be used to create a salt gradient. Elution buffer is consistently being drawn from the chamber into the mixing chamber, thereby altering its buffer concentration. Generally, the buffer placed into the chamber is usually of high initial concentration, whereas the buffer placed into the stirred chamber is usually of low concentration. As the high concentration buffer from the left chamber is mixed and drawn into the column, the buffer concentration of the stirred column gradually increase. Altering the shapes of the stirred chamber, as well as of the limit buffer, allows for the ...
The main use of litmus is to test whether a solution is acidic or basic. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5-8.3 at 25 °C (77 °F). Neutral litmus paper is purple.[1] Litmus can also be prepared as an aqueous solution that functions similarly. Under acidic conditions, the solution is red, and under alkaline conditions, the solution is blue. Wet litmus paper can also be used to test for water-soluble gases that affect acidity or alkalinity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, turn the red litmus paper blue. ...
... is a fundamental chemical reaction and is a step in many stoichiometric and catalytic processes. Some ions and molecules can undergo more than one protonation and are labeled polybasic, which is true of many biological macromolecules. Protonation and deprotonation (removal of a proton) occur in most acid-base reactions; they are the core of most acid-base reaction theories. A Brønsted-Lowry acid is defined as a chemical substance that protonates another substance. Upon protonating a substrate, the mass and the charge of the species each increase by one unit, making it an essential step in certain analytical procedures such as electrospray mass spectrometry. Protonating or deprotonating a molecule or ion can change many other chemical properties, not just the charge and mass, for example hydrophilicity, reduction potential, and optical properties can ...
Harper, J.P (1936). Antipov, Evgeny; Bismayer, Ulrich; Huppertz, Hubert; Petrícek, Václav; Pöttgen, Rainer; Schmahl, Wolfgang; Tiekink, E.R.T.; Zou, Xiaodong, eds. "Crystal Structure of Sodium Carbonate Monohydrate, Na2CO3. H2O". Zeitschrift für Kristallographie - Crystalline Materials. De Gruyter. 95 (1): 266-273. doi:10.1524/zkri.1936.95.1.266. ISSN 2196-7105. Retrieved 2014-07-25 ...
Cyfansoddyn cemegol halocromig ("halochromic chemical compound") a ychwanegir bob yn dipyn i hydoddiant yw dangosydd pH er mwyn penderfynu beth yw ei pH: asid ynteu alcali. Detector neu ganfodydd cemegol ydyw, felly, sy'n dangos bodolaeth ionau Hydrogen (H+) yn y model Arrhenius. Fel arfer, mae'r dangosydd yn newid lliw'r hydoddiant, yn dibynnu ar y pH. Mae sylwedd gyda gwerth o 7.0 neu ragor yn alcali, a pH o 7.0 neu fwy yn asidig. Mae hydoddiant o 7.0 yn cael ei gyfri yn niwtral. ...
இம்முறையில் சுமார் 15 மில்லியன் கிலோகிராம் கிளைசின் ஒரு வருடத்திற்கு உற்பத்திச் செய்யப்படுகிறது[6].. இதனுடையக் காடித்தன்மை எண்கள்: 2.35 மற்றும் 9.78. எனவே, அமிலக்காரக் குறியீடு (pH) 9.78 -ட்டிற்கு மேல் பெரும்பாலான கிளைசின் அமைன் எதிரயனிகளாக உள்ளது, H2NCH2CO2-. அமிலக்காரக் குறியீடு (pH) 2.35 -க்கு கீழே கிளைசின் கரைசல்கள் பெரும்பாலும் கார்பாக்சிலிக் அமில நேரயனிகளாகவே உள்ளது, H3N+CH2CO2H. இதனுடையச் ...
பாஸ்பீன் C3v மூலக்கூறு சமச்சீருடன் கூடிய ஒரு முக்கோணப் பிரமீடு அமைப்பு மூலக்கூறு ஆகும். இதிலுள்ள P-H பிணைப்பின் நீளம் 1.42 Å, H-P-H ன் பிணைப்புக் கோணம் 93.5° மற்றும் இருமுனைவுத்திருப்புதிறன் 0.58 D. இத்திருப்புத்திறன் மீத்தைல் தொகுதி வரிசைச் சேர்மங்களுடன் பதிலீடு செய்யப்படும்போது படிப்படியாக அதிகரிக்கிறது : உதாரணமாக CH3PH2, 1.10 D; (CH3)2PH, 1.23 D; ஆனால் அமைன்கள் பதிலீட்டின் போது இத்திருப்புத்திறன் ...
... hydrogen electrode explanation free. What is hydrogen electrode? Meaning of hydrogen electrode medical term. What does hydrogen ... Looking for online definition of hydrogen electrode in the Medical Dictionary? ... used in determination of hydrogen ion concentration.. indifferent electrode one larger than a therapeutic electrode, dispersing ... Related to hydrogen electrode: calomel electrode, Standard hydrogen electrode. electrode. [e-lek´trōd] either of two terminals ...
The hydrogen-ion concentration wasmeasured with a glass electrode. The bentonite-clay suspensions were preparedin the ...
... hydrogen ion concentration). The pH electrode is at the end of a flexible lead which may be inserted into the esophagus or ... 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and ... When necessary, the electrode may be removed by the user. (b) Classification. Class II, subject to the following special ... The electrode is held against the stone in a water-filled bladder and repeated electrical discharges between the two poles of ...
McClendon J. F. New hydrogen electrodes and rapid methods of determining hydrogen ion concentrations. - Amer. J. Physoil., 1915 ...
1924 The Electrical Charge on a Clay Colloid as Influenced by Hydrogen-Ion Concentration and by Different Salts. With W. C. ... 1916 Acidity and Adsorption in Soils as Measured by Hydrogen Electrode. With L. T. Sharp. J. Agr. Res., 7:3. 1917 The Effect of ... Hydrogen-Ion Effects and the Accumulation of Salt by Barley Roots as Influenced by Metabolism. With T. C. Broyer. Am. J. Bot., ... Hydrogen and Hydroxyl Ion Concentration on the Growth of Barley Seedlings. Soil Sci., 3(6) 547-560. 1918 Relation of Carbon ...
What is esophageal electrode? Meaning of esophageal electrode medical term. What does esophageal electrode mean? ... Looking for online definition of esophageal electrode in the Medical Dictionary? esophageal electrode explanation free. ... used in determination of hydrogen ion concentration.. indifferent electrode one larger than a therapeutic electrode, dispersing ... active electrode therapeutic electrode.. calomel electrode one capable of both collecting and giving up chloride ions in ...
McClendon J. F. New hydrogen electrodes and rapid methods of determining hydrogen ion concentrations. Amer. J. Physiol., 1915, ... The hydrogen ion concentrations of the contents of the small intestine. J. of Biological Chemistry, Feb 19, 1918. XXXIV, No 1. ... McClendon J. F. A direct reading potenciometer for measuring hydrogen ion concentration. Amer. J. Physiol., 1915, 38, 2, 186. ... stomachs and duodenums of adults and infants plotted with the acid of imported methods of measuring hydrogen ion concentration ...
... are one of the most prominent clean energy technologies to achieve the hydrogen utilization, to solve the low efficiency and ... are one of the most prominent clean energy technologies to achieve the hydrogen utilization, to solve the low efficiency and ... ΔGU = -eU, in which U is the potential related to the standard hydrogen electrode. ΔGpH = -kTln10 x pH, which is the corrected ... ions depending on the concentration. According to the previous works, pH is set as 0 in acid medium and 14 in alkaline medium. ...
Later he devised a glass electrode to measure hydrogen ion concentration through the electric potential across a piece of thin ... did not emphasize the application to the measurement of hydrogen ion concentration. ... He studied the nature and rate of the electrode process for the quinine-quinol system and, interested in the nature and rate of ... He found the carbon-to-carbon linkage in hydrocarbons to have a greater thermal stability than the carbon-to-hydrogen linkage ...
If the electrode is calibrated in terms of known hydrogen ion concentrations it would be better to write p[H] rather than pH, ... In aqueous solution the concentration of the hydroxide ion is related to the concentration of the hydrogen ion by ... The concentration quotient K. c. {\displaystyle K^{c}}. has the dimension 1/concentration, but the thermodynamic equilibrium ... Replace each concentration term [. X. ]. {\displaystyle [X]}. by the dimensionless quotient [. X. ]. [. X. 0. ]. {\displaystyle ...
A Description of the Glass Electrode and Its Use in Measuring Hydrogen Ion Concentration," in Journal of Biological Chemistry ... and state of aggregation are markedly affected by the response of their ionizable groups to the hydrogen ion concentration (pH ... Mirsky began his work in Cohns laboratory with studies of pH in the blood of developing chicks, using a glass electrode ... Their major approach was the differential use of neutral sodium chloride solutions of varying concentrations: physiological ...
Further it could be correlated to any other measure of hydrogen ion concentration, typically using a glass electrode, but other ... methods including ion selective field effect transistor electrodes could be used. As the increasing pH in meat is correlated ...
F-23 type glass electrodehydrogen ion concentration manufactured by Horiba, Ltd.-style hydrogen-ion concentration instructions ... When the Mg ion exists alone, the effect of the luminescent stabilization isremarkable in a concentration of more than 0.5 mM ... Forexample, a Mg ion is effective for the stabilization of the luminescence in the firefly bioluminescent system. When Mg ion ... of Mg ion in the luminescent system and it is enhanced according to increase of the concentration. For example, the ...
... it is possible to measure the concentration of hydrogen ions directly, if the electrode is calibrated in terms of hydrogen ion ... The concentration of hydroxide ions in water is related to the concentration of hydrogen ions by ... between an electrode sensitive to the hydrogen ion activity and a reference electrode, such as a calomel electrode or a silver ... so in neutral solution of a salt both the hydrogen ion concentration and hydroxide ion concentration are about 10-7 mol dm-3. ...
... in which hydrogen gas is bubbled over a platinum electrode immersed in a solution having a known concentration of hydrogen ions ... one must use unit activity rather than concentration of hydrogen ions and unit fugacity rather than unit pressure of hydrogen ... This historically important reference electrode is called the standard hydrogen electrode (SHE) if a standard solution of acid ... is designated as the standard electrode or standard reference electrode with which other electrodes can be compared. ...
Potassium ions usually cause less error than sodium ions. *Acidic error range - at very high concentration of hydrogen ions ( ... The pH electrode is an example of a glass electrode that is sensitive to hydrogen ions. Glass electrodes play an important part ... A glass electrode is a type of ion-selective electrode made of a doped glass membrane that is sensitive to a specific ion. The ... located on opposite sides of the glass membrane is proportional to the concentration of acid (hydrogen ion concentration).[1] ...
72452S03-I This project will develop and commercialize ion-conducting thermally stable polymers for use as high-temperature ... allowing control of both their location and concentration. The new materials will be much less costly than fluoropolymers, and ... they require a cumbersome pressurized vessel for hydrogen storage. In comparison, DMFCs would need simply a liquid storage ... High Temperature-Stable Membrane Electrode Assemblies for Fuel Cells Fabricated via Ink Jet Deposition. Printer-friendly ...
... permits selective passage of ions and the electrode can be used as an ions sensor for measuring the concentration of ions in ... the given solution of an unknown hydrogen ion concentration and the reference solution of a constant hydrogen ion concentration ... the hydrogen electrode and the quinhydrone electrode have been known as electrodes available for measuring the concentration of ... 1. A system for measuring the concentration of hydrogen ions in a test solution by electrode potential response or current ...
Changes in pH were monitored with a glass electrode calibrated daily in hydrogen ions concentrations. The titration data within ... 3 NaCl and at different metal ion concentrations. ... Gallium(III) Ion Hydrolysis under Physiological Conditions ...
... that depends upon the hydrogen ion concentration of the reaction medium and the benzoquinone and hydroquinone concentrations. ... The so-called quinhydrone electrode, containing equivalent amounts of p-benzoquinone and hydroquinone, is used to determine ... The quinone returns the electron back across the membrane but takes a hydrogen ion (H+) along with it. This transport of H+ ... hydrogen ion concentrations of unknown solutions. Hydroquinone is used principally as a photographic developing agent. ...
Avdeef A, Bucher JJ (1978) Accurate measurements of the concentration of hydrogen ions with a glass electrode: calibrations ... Avdeef A, Comer JE, Thomson SJ (1993) pH-Metric log P. 3. Glass electrode calibration in methanol-water, applied to pKa ... Marechal Y (2006) The Hydrogen Bond and the Water Molecule: The Physics and Chemistry of Water, Aqueous and Bio-Media. Elsevier ...
Hydrogen ion concentration (pH) in blood is usually determined by means of which of the following electrodes? ... The measurement of the amount of electricity passing between two electrodes in an electro-chemical cell is the principle of:. * ... The different water content of erythrocytes and plasma makes true glucose concentrations in whole blood a function of the? ... Which of the following is the formula for calculating the unknown concentration based on Beers Law (A= absorbance, C= ...
Susceptibility to chloride ion attack was determined as a function of time in solution, chloride ion concentrations, and open ... Samples prepassivated in oxygen saturated 1n H2SO4 at 0.6 V normal hydrogen electrode and then released to open circuit and ... were subsequently exposed to chloride ion concentrations ranging from 5 to 44 parts per thousand. ... the Bureau of Mines has characterized the effect of aggressive ions on the corrosion and passive behavior of two stainless ...
where (aH) is the hydrogen ion activity and [H+] the hydrogen ion concentration. ... As measured with the glass electrode, pH is equal to the negative logarithm of the hydrogen ion activity. Activity is ... As with hydrogen ion concentrations and pH, the range of values taken by Ka is very large so that a logarithmic scale of pKa is ... and 1000-fold differences in the hydrogen ion concentration. The acidity or alkalinity of an environment has a profound effect ...
Ion sensitive based electrodes are one of the most commonly used methods to measure concentrations of H2S in plasma with a ... A typical three-electrode configuration, consisting of a working electrode, a reference electrode, and a counter electrode, is ... This review details up-to-date research on the electrochemical detection of hydrogen sulfide (ion selective electrodes, ... made a full detailed procedure to rapidly estimate H2S concentration in blood using a sulfide ion electrode (Model 94-16A).52 ...
  • Because of the ion-exchange nature of the glass membrane, it is possible for some other ions to concurrently interact with ion-exchange centers of the glass and to distort the linear dependence of the measured electrode potential on pH or other electrode function. (wikipedia.org)
  • This is 100th anniversary of the glass pH electrode yet we still do not know much about what affects their life. (modelingandcontrol.com)
  • While the fundamentals of the glass pH electrode have not changed in a hundred years, there have been significant improvements in the glass formulation and construction so that it can handle high pH and high temperature fluids and repeated sterilizations. (modelingandcontrol.com)
  • where E is a measured potential , E 0 is the standard electrode potential, that is, the electode potential for the standard state in which the activity is one. (thefullwiki.org)
  • The potential difference across a reversible cell made up of any electrode and a SHE is called the reversible potential of that electrode, E. If this other electrode is also being operated under standard conditions of pressure and concentration, then the reversible potential difference across the cell is the standard electrode potential E 0 of that electrode. (corrosion-doctors.org)
  • Yutaka TSUJIMURA, Masataka YAMANE, Shin-ichi WAKIDA Analytical Sciences 17 (4), Cited by: A considerable interest in development surfactant- sensitive electrodes has aroused in among A which those of liquid ion-exchange, polymer membrane types are of great importance. (desi.pw)
  • These types of electrodes have been used industrially for years, but we do not understand why they actually work," explains Wolfgang Schuhmann, Head of the Department of Analytical Chemistry and CES. (phys.org)
  • His investigations can be divided into four classes: synthesis of amino acids, analytical studies, work on hydrogen ion concentration, and studies on proteins. (encyclopedia.com)
  • Nevertheless, these steps tend to complicate the experimental procedure, and added to the delicate handling of mercury electrodes, these methods become less suited for real analytical applications. (hindawi.com)
  • The purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, and/or monitoring fluorides, hydrogen fluoride, and fluorine, its metabolites, and other biomarkers of exposure and effect to fluorides, hydrogen fluoride, and fluorine. (cdc.gov)
  • A gate insulating film, and a gate electrode are then formed, and an impurity is implanted in a self-alignment manner. (patents.com)
  • Further, a gate insulating film and a gate electrode are formed. (google.ca)
  • A nurober of new based for example on mixtures of metal chalcogenides, as weil as enzyme electrodes and coated wire electrodes, are described. (desi.pw)
  • Simultaneous assay of glucose, lactate, L-glutamate and hypoxanthine levels in a rat striatum using enzyme electrodes based on neutral red-doped si. (nih.gov)
  • Simultaneous assay of glucose, lactate, L-glutamate and hypoxanthine levels in a rat striatum using enzyme electrodes based on neutral red-doped silica nanoparticles. (nih.gov)
  • The high sensitivity of the NRDS modified enzyme electrode system enables the simultaneous monitoring of trace levels of glucose, L-glutamate, lactate and hypoxanthine in diluted dialysate samples from a rat striatum. (nih.gov)
  • The enzyme electrodes showed interesting kinetic data. (naver.com)