All articles starting with N
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Nuclear winter
Nuclear winter is the hypothesized severe cooling and darkness that would follow nuclear war, first modeled in a 1983 paper by Turco, Toon, and Sagan's colleagues.
Nuclear-powered aircraft
A nuclear-powered aircraft is a crewed aircraft carrying an onboard fission reactor to drive its engines, researched by the US and Soviet Union but never flown under reactor power.
Nuclear-powered icebreaker
A nuclear-powered icebreaker is a surface ship driven by nuclear reactors, giving it the power to break thick sea ice and years of operation without refueling.
Nuclear-weapon-free zone
A nuclear-weapon-free zone (NWFZ) is a region whose states pledge not to make, acquire, test, or hold nuclear weapons, with five treaty-based zones covering most of the Southern Hemisphere.
Nuclease
Nuclease (nucleases; e.g., Serratia marcescens nuclease, EC 3.1.30.2): enzymes that cleave phosphodiester bonds in DNA or RNA. Includes restriction enzymes, RNA-guided Cas9, RNases, and food-grade nuclease preparations such as GRN 1146.
Nuclease protection assay
The nuclease protection assay (NPA) is a molecular biology method that quantifies and maps specific RNA or DNA using a labeled antisense probe and nuclease digestion.
Nuclease SbcCD subunit C-like
Nuclease SbcCD subunit C-like (SbcC) proteins are bacterial Rad50 orthologs, the ATPase subunit of the SbcCD hairpin nuclease with SbcD (Mre11 ortholog), cleaving hairpins, processing convergent replication forks, and repairing crosslinks.
Nucleata
Nucleata (Quenstedt, 1868) is an extinct genus of terebratulid brachiopods, type species Nucleata nucleata (von Schlotheim, 1820), known from Jurassic and Early Cretaceous marine deposits in Europe and Indonesia.
Nucleate boiling
Nucleate boiling is a boiling mode in which vapor bubbles grow at nucleation sites on a heated surface and detach, the most efficient boiling regime for heat transfer.
Nucleate cell
Nucleate cell (CL:0002242), Cell Ontology class defined as a cell containing at least one nucleus; parent of single and multinucleate cell, leukocyte, and nucleate erythrocyte.
Nucleated red blood cell
Nucleated red blood cell (NRBC, normoblast, erythroblast): immature red cell precursor retaining a nucleus; absent from adult peripheral blood, normal in newborns, and counted by automated hematology analyzers.
Nucleated settlement
Nucleated settlement, also called clustered settlement, is a rural settlement pattern where buildings cluster around a center such as a church, green, or water source, with farmland outside; contrasted with dispersed and linear patterns.
Nucleation
Nucleation, or the nucleation point, is the first step of phase transformations such as condensation, solidification, and crystallization, where rare fluctuations overcome a surface-energy barrier.
Nucleation overpotential
Nucleation overpotential (ηn) is the extra electrode potential, beyond the thermodynamic deposition potential, required to form stable metal nuclei during electroplating, appearing as a voltage spike at the onset of lithium deposition.
Nucleic acid
Nucleic acid: DNA and RNA, nucleotide polymers storing and expressing genomic information in all cells and viruses; discovered by Miescher in 1869; 29 FDA-approved nucleic acid therapeutics as of 2025.
Nucleic acid amplification test
A nucleic acid amplification test (NAAT) is a diagnostic method that detects a pathogen by copying its DNA or RNA many times, most commonly using PCR, and reports a qualitative or quantitative result.
Nucleic acid binding NABP
NABP (nucleic acid binding protein): human NABP1/hSSB2 and NABP2/hSSB1, single OB-fold ssDNA/RNA binding proteins in the SOSS complex with INTS3 and INIP, acting in DNA repair, checkpoints, and R-loop regulation.
Nucleic acid double helix
The nucleic acid double helix, known as the DNA double helix or Watson-Crick structure, is the paired spiral of DNA or RNA strands, described by Watson and Crick in 1953.
Nucleic acid extraction
Nucleic acid extraction is the laboratory method for isolating DNA or RNA from cells or tissues, typically by lysing the sample and separating the nucleic acids from contaminants.
Nucleic acid hybridization
Nucleic acid hybridization, also called a hybridization assay, is a bench biology method where complementary single-stranded DNA or RNA pair, detecting, quantifying, or locating specific sequences.
Nucleic acid ligation
Nucleic acid ligation: enzyme-driven joining of 3′-OH and 5′-phosphate nucleic acid ends into phosphodiester bonds by DNA and RNA ligases (T4, E. coli LigA, thermostable ligases), via a three-step AMP-transfer mechanism used in cloning, diagnostics, and drug targeting.
Nucleic acid quantitation
Nucleic acid quantitation measures DNA or RNA concentration and purity, mainly by UV absorbance at 260 nm (NanoDrop, DeNovix) or by specific fluorescent dyes (Qubit, PicoGreen), which differ in sensitivity and accuracy.
Nucleic acid sequence
Nucleic acid sequence: the ordered bases (A, C, G, T/U) of DNA or RNA. Determined by Sanger, short-read NGS, and long-read methods; stored in GenBank; cost fell to ~$1,100 per genome.
Nucleic acid sequence-based amplification
Nucleic acid sequence-based amplification (NASBA) is an isothermal laboratory method that exponentially amplifies RNA at about 41 °C, widely used to detect RNA viruses and viable bacteria.
Nucleic acid sequencing
Nucleic acid sequencing determines the order of nucleotides in DNA or RNA, from Sanger chain termination to Illumina short reads and long-read single-molecule methods like PacBio and Oxford Nanopore.
Nucleic acid structure
Nucleic acid structure is the organization of DNA and RNA molecules across four levels, from nucleotide sequence and base pairing to 3D folding and interactions with proteins or other nucleic acids.
Nucleic acid-linked immuno-sandwich assay
A nucleic acid-linked immuno-sandwich assay detects proteins by combining an antibody sandwich immunoassay with an amplified nucleic acid label, giving 10- to 1,000-fold better sensitivity than ELISA.
Nucleix
Nucleix is an Israeli liquid-biopsy cancer diagnostics company founded in 2008, based in Rehovot, Israel and San Diego, that develops DNA methylation tests including Bladder EpiCheck and Lung EpiCheck.
Nucleobase cation symporter-1, NCS1
Nucleobase cation symporter-1 (NCS1) family: secondary active membrane transporters in bacteria, archaea, fungi, and plants that import nucleobases, hydantoins, and vitamins via proton or sodium symport; distinct from neuronal calcium sensor NCS1.
Nucleobindin
Nucleobindin (calnuc, NEFA): a calcium- and DNA-binding protein family, NUCB1 and NUCB2. NUCB1 is a Golgi calcium-storage protein regulating Gαi; NUCB2 encodes the satiety peptide nesfatin-1, whose receptor remains unidentified.