Spectrometry, X-Ray Emission: The spectrometric analysis of fluorescent X-RAYS, i.e. X-rays emitted after bombarding matter with high energy particles such as PROTONS; ELECTRONS; or higher energy X-rays. Identification of ELEMENTS by this technique is based on the specific type of X-rays that are emitted which are characteristic of the specific elements in the material being analyzed. The characteristic X-rays are distinguished and/or quantified by either wavelength dispersive or energy dispersive methods.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Spectrophotometry, Atomic: Spectrophotometric techniques by which the absorption or emmision spectra of radiation from atoms are produced and analyzed.Arsenates: Inorganic or organic salts and esters of arsenic acid.X-Rays: Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard X-rays are the higher energy, shorter wavelength X-rays. Soft x-rays or Grenz rays are less energetic and longer in wavelength. The short wavelength end of the X-ray spectrum overlaps the GAMMA RAYS wavelength range. The distinction between gamma rays and X-rays is based on their radiation source.Synchrotrons: Devices for accelerating protons or electrons in closed orbits where the accelerating voltage and magnetic field strength varies (the accelerating voltage is held constant for electrons) in order to keep the orbit radius constant.Mercury: A silver metallic element that exists as a liquid at room temperature. It has the atomic symbol Hg (from hydrargyrum, liquid silver), atomic number 80, and atomic weight 200.59. Mercury is used in many industrial applications and its salts have been employed therapeutically as purgatives, antisyphilitics, disinfectants, and astringents. It can be absorbed through the skin and mucous membranes which leads to MERCURY POISONING. Because of its toxicity, the clinical use of mercury and mercurials is diminishing.Fluorescence: The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.Lead: A soft, grayish metal with poisonous salts; atomic number 82, atomic weight 207.19, symbol Pb. (Dorland, 28th)X-Ray Absorption Spectroscopy: Analysis of the energy absorbed across a spectrum of x-ray energies/wavelengths to determine the chemical structure and electronic states of the absorbing medium.Fluorescence Polarization: Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction.Fluorescence Polarization Immunoassay: Fluoroimmunoassay where detection of the hapten-antibody reaction is based on measurement of the increased polarization of fluorescence-labeled hapten when it is combined with antibody. The assay is very useful for the measurement of small haptenic antigens such as drugs at low concentrations.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Chromatography, Liquid: Chromatographic techniques in which the mobile phase is a liquid.Tandem Mass Spectrometry: A mass spectrometry technique using two (MS/MS) or more mass analyzers. With two in tandem, the precursor ions are mass-selected by a first mass analyzer, and focused into a collision region where they are then fragmented into product ions which are then characterized by a second mass analyzer. A variety of techniques are used to separate the compounds, ionize them, and introduce them to the first mass analyzer. For example, for in GC-MS/MS, GAS CHROMATOGRAPHY-MASS SPECTROMETRY is involved in separating relatively small compounds by GAS CHROMATOGRAPHY prior to injecting them into an ionization chamber for the mass selection.Spectrometry, Mass, Electrospray Ionization: A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry.Diphenylhexatriene: A fluorescent compound that emits light only in specific configurations in certain lipid media. It is used as a tool in the study of membrane lipids.Gasoline: Volative flammable fuel (liquid hydrocarbons) derived from crude petroleum by processes such as distillation reforming, polymerization, etc.Petroleum: Naturally occurring complex liquid hydrocarbons which, after distillation, yield combustible fuels, petrochemicals, and lubricants.Kerosene: A refined petroleum fraction used as a fuel as well as a solvent.Lead PoisoningPica: The persistent eating of nonnutritive substances for a period of at least one month. (DSM-IV)Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.Biometric Identification: A method of differentiating individuals based on the analysis of qualitative or quantitative biological traits or patterns. This process which has applications in forensics and identity theft prevention includes DNA profiles or DNA fingerprints, hand fingerprints, automated facial recognition, iris scan, hand geometry, retinal scan, vascular patterns, automated voice pattern recognition, and ultrasound of fingers.BooksPortraits as Topic: Graphic representations, especially of the face, of real persons, usually posed, living or dead. (From Thesaurus for Graphic Materials II, p540, 1995)History, 17th Century: Time period from 1601 through 1700 of the common era.History of DentistrySocieties, Scientific: Societies whose membership is limited to scientists.Book SelectionHistory, 18th Century: Time period from 1701 through 1800 of the common era.Magic: Beliefs and practices concerned with producing desired results through supernatural forces or agents as with the manipulation of fetishes or rituals.Click Chemistry: Organic chemistry methodology that mimics the modular nature of various biosynthetic processes. It uses highly reliable and selective reactions designed to "click" i.e., rapidly join small modular units together in high yield, without offensive byproducts. In combination with COMBINATORIAL CHEMISTRY TECHNIQUES, it is used for the synthesis of new compounds and combinatorial libraries.History, 19th Century: Time period from 1801 through 1900 of the common era.Chemistry, Physical: The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.Molecular Dynamics Simulation: A computer simulation developed to study the motion of molecules over a period of time.Chemistry, Clinical: The specialty of ANALYTIC CHEMISTRY applied to assays of physiologically important substances found in blood, urine, tissues, and other biological fluids for the purpose of aiding the physician in making a diagnosis or following therapy.MinnesotaPhysicochemical Phenomena: The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.Natural Science Disciplines: The sciences dealing with processes observable in nature.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Interdisciplinary Studies: Programs of study which span the traditional boundaries of academic scholarship.Software: Sequential operating programs and data which instruct the functioning of a digital computer.