Chemistry terminology · MLC-0109

Chemistry terms: U (101)

• µ-A prefix used in coordination chemistry to denote a bridging ligand that connects two or more metal centers...
• UbiquitinA small, highly conserved regulatory protein found in eukaryotic cells that tags other proteins for...
• UlcerA localized defect or excavation of the surface of an organ or tissue, resulting from the shedding of...
• Ultimate biodegradationThe complete breakdown of an organic compound by microorganisms in the presence of oxygen, resulting in its...
• Ultimate capacityThe maximum amount of a solute that can be extracted from a given volume of aqueous phase by a specific...
• UltrafiltrateThe liquid that passes through a semipermeable membrane during ultrafiltration, a process that separates...
• UltrafiltrationA membrane separation process that uses hydrostatic pressure to force liquids through a semi-permeable...
• Ultrafine particleA particulate matter with a diameter less than 100 nanometers (0.1 micrometer). These particles are of...
• Ultra-high throughputA screening methodology characterized by the rapid testing of an extremely large number of samples, often...
• UltramicroelectrodeAn electrode with at least one characteristic dimension, such as its radius or width, in the micrometer or...
• Ultra-shallow depth profileA measurement of the elemental or molecular composition as a function of depth, extending only a few...
• Ultrasonic detectorA device that measures the concentration of a substance by detecting changes in the speed of sound through a...
• Ultrasonic nebulizersDevices that generate a fine aerosol from a liquid sample by using high-frequency ultrasonic vibrations. A...
• UltrasonographyA medical imaging technique that uses high-frequency sound waves to create real-time images of internal body...
• UltrasoundSound waves with frequencies higher than the upper audible limit of human hearing, typically above 20...
• Ultrasound-assisted extractionA method that uses high-frequency sound waves to enhance the transfer of target compounds from a solid or...
• UltravioletElectromagnetic radiation with wavelengths shorter than visible light but longer than X-rays, typically...
• Ultraviolet doseThe total amount of ultraviolet (UV) radiation energy absorbed by a substance or system over a specific...
• Ultraviolet stabilizerA chemical additive incorporated into materials, particularly polymers, to protect them from degradation...
• Umbilical arteryA pair of arteries present in the fetus that carry deoxygenated blood and waste products from the fetal...
• Umbilical cordA flexible, tube-like structure that connects a developing fetus to the placenta, facilitating the exchange...
• Umbilical herniaA protrusion of abdominal contents, such as intestine or omentum, through a weakness in the abdominal wall at...
• Umbilical veinA single vein present in the fetus that carries oxygenated, nutrient-rich blood from the placenta to the...
• UmbilicusThe scar on the abdomen that marks the former attachment point of the umbilical cord in a fetus. This...
• Umpire sampleA portion of a material reserved for independent analysis in case of a dispute regarding the initial...
• UmpolungThe chemical modification of a functional group to reverse its inherent polarity. This synthetic strategy...
• Unactivated adsorption processAn adsorption process that occurs without an activation energy barrier. The rate of adsorption is not limited...
• Unary systemA thermodynamic system composed of a single chemical component, meaning only one type of chemical substance...
• Unbiased stereologyA set of quantitative morphological methods for estimating three-dimensional structural parameters, such as...
• UncertaintyA parameter associated with the result of a measurement that characterizes the dispersion of the values that...
• Uncertainty factorA numerical value used in risk assessment to account for limitations in the available data when extrapolating...
• Uncertainty of measurementA parameter associated with the result of a measurement that characterizes the dispersion of the values that...
• Unconditioned stimulusA stimulus that naturally and automatically triggers a reflexive or innate response without any prior...
• UnconsciousA state of being unaware of one's surroundings, thoughts, or feelings, often due to injury, illness, or the...
• UncusA hook-shaped anterior extremity of the parahippocampal gyrus in the temporal lobe of the brain. This region...
• Underdetermined systemA system of equations or a model where the number of unknown variables exceeds the number of independent...
• UnderfittingA condition in statistical modeling or machine learning where a model is too simple to capture the underlying...
• UndersamplingThe process of acquiring data at a sampling rate lower than twice the highest frequency component present in...
• Undescended testisA developmental condition in males where one or both testes fail to descend from the abdominal cavity into...
• Uniaxial pressingA method of compacting powdered materials, such as polymer or ceramic powders, by applying pressure in a...
• Uniaxial sampleA material in which the constituent molecules or structural units are preferentially oriented along a single...
• Unified atomic mass unitA standard unit of mass for expressing the masses of atoms, molecules, and subatomic particles, symbolized as...
• Uniform corrosionA form of corrosion that occurs evenly over the entire exposed surface of a material, resulting in a...
• Uniform dispersionA system in which the components, such as particles in a matrix or comonomer units along a polymer chain, are...
• Uniform polymerA polymer composed of molecules that are identical in terms of their constitution, configuration, and degree...
• Uniformly labelledDescribing a chemical compound in which a specific isotope is distributed statistically evenly among all...
• Uniformly labelled tracerA chemical compound in which a specific isotope, such as a radioisotope, is distributed evenly throughout all...
• UnimerA single, non-aggregated macromolecule in a solution that is capable of self-assembly into a micelle or other...
• UnimolecularDescribing a reaction or process involving a single molecule as the reactant in the rate-determining step...
• Unimolecular dissociationA process in mass spectrometry where a single excited ion breaks apart into smaller fragment ions and neutral...
• UnitA specific magnitude of a physical quantity that is defined and adopted by convention or by law, used as a...
• Unit cellThe smallest repeating unit in a crystal lattice that, when translated in three dimensions, generates the...
• Unit mass resolutionA characteristic of a mass spectrometer indicating its ability to distinguish between ions that differ in...
• Unit riskThe estimated excess lifetime cancer risk per unit of exposure to a carcinogen, typically expressed as the...
• Unit systemA collection of units of measurement and rules relating them to each other, used to quantify physical...
• Unitary quantityA quantity that represents a single, indivisible entity or event, often used in counting or enumeration. It...
• Universal calibrationA method used in size-exclusion chromatography (SEC) to determine the molar mass of a polymer sample...
• Universal detectorA device in chromatography that responds to nearly all components eluting from the separation column, rather...
• Universal indicatorA mixture of several different pH indicators that exhibits multiple color changes over a broad range of pH...
• Unmet medical needA medical condition for which there is currently no satisfactory diagnostic, preventive, or therapeutic...
• Unperturbed conformational stateThe average conformation of a polymer chain in a theta solvent, where long-range interactions between...
• Unperturbed dimensionsThe characteristic dimensions of a polymer chain in a theta solvent, where excluded volume effects are absent...
• Unperturbed end-to-end distanceThe average distance between the two ends of a polymer chain when it is in an unperturbed conformational...
• Unperturbed end-to-end vectorA vector connecting the two ends of a polymer chain when it is in an unperturbed conformational state, such...
• Unperturbed radius of gyrationThe radius of gyration of a polymer chain when it is in an unperturbed conformational state, typically in a...
• UnreactiveDescribing a chemical species that exhibits low chemical reactivity under specified conditions. Such species...
• UnresponsivenessA state in which the immune system fails to mount a protective or damaging response to an antigen, despite...
• Unsaturated solutionA solution that contains a concentration of solute lower than its solubility limit at a given temperature and...
• UnsaturationThe presence of double or triple bonds between carbon atoms in an organic molecule, or between carbon and...
• UnstableDescribing a chemical species that possesses a higher molar Gibbs energy compared to a specific reference...
• Unstable ionAn ion that possesses excess internal energy, leading to its fragmentation or rearrangement into more stable...
• Unsupervised classificationA chemometric method for grouping data points into clusters based on their inherent similarities without...
• Unweighted pair group method with arithmetic meanA hierarchical clustering algorithm that constructs a dendrogram by iteratively merging the two closest...
• UpconversionA photophysical process in which the sequential or simultaneous absorption of two or more photons leads to...
• Uphill transportThe movement of a substance across a membrane or barrier against its concentration gradient, from a region of...
• Upper boundaryThe highest value within a specified range or distribution of a measured quantity. This limit defines the...
• Upper critical solution temperatureThe maximum temperature above which two components, such as a polymer and a solvent, are completely miscible...
• Upper limit of measurementThe highest value of a quantity that a measuring instrument or method can reliably determine while...
• Upper motor neuronA neuron that originates in the cerebral cortex or brainstem and carries motor information down to the spinal...
• UpstreamThe region or side of a membrane from which the feed solution is introduced in a separation process. It is...
• Upstream waterThe body of water located at a point in a river or stream that is closer to the source and has not yet been...
• UptakeThe process by which a substance is absorbed into a cell, tissue, or organism from its surrounding...
• Uptake rate constantA proportionality constant that describes the rate at which a substance is absorbed by an organism or a...
• UreidesOrganic compounds containing the functional group R-NH-CO-NH-CO-R', which are N-substituted derivatives of...
• UrethanesOrganic compounds containing a carbamate functional group, which consists of an amino group and an ester...
• UrethraA tube that carries urine from the bladder to the outside of the body. In males, it also serves as the...
• UrineA biological fluid produced by the kidneys through the filtration of blood to remove metabolic waste products...
• UrogenitalRelating to both the urinary and genital organs, which are closely associated in their development and...
• Urogenital sinusAn embryonic structure that forms during development and gives rise to parts of the urinary and reproductive...
• Uronic acidsA class of sugar acids containing both a carboxyl group and an aldehyde group. They are formally derived from...
• Uronium saltsCationic derivatives of urea, formally obtained by the N-protonation or N-substitution of urea with a...
• UrticariaA skin reaction, also known as hives, characterized by the sudden appearance of raised, itchy welts or wheals...
• Useful ion yieldThe ratio of the number of detected ions of a specific species to the total number of atoms of that species...
• Useful spatial resolutionThe smallest distance between two features on a sample surface that can be distinguished as separate entities...
• Uterine cryptAn invagination or pocket within the uterine lining (endometrium) where the embryo implants and begins its...
• Uterine cycleThe series of cyclic changes that occur in the endometrium, the inner lining of the uterus, in response to...
• UterotrophicDescribing a substance or effect that causes an increase in the size or weight of the uterus. This change is...
• Uterotrophic assayA standardized biological test used to detect substances that have estrogenic or antiestrogenic activity by...
• UterusA hollow, muscular organ in female mammals that is part of the reproductive system. It serves as the site for...
• UV photochemical digestionA sample preparation technique that uses ultraviolet radiation to break down organic matrices into simpler...
• UvulaA conical projection of soft tissue that hangs from the posterior margin of the soft palate, positioned at...

101 of 13,678 terms in Chemistry terminology (MLC-0109). Request the full dataset.