This is a working overview of Stability, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-14 and is reviewed periodically as new material appears.
Nicotinamide mononucleotide, commonly abbreviated NMN, is a naturally occurring nucleotide found in the cells of many organisms. Its structure consists of a nicotinamide group linked to a ribose sugar that carries a phosphate group. NMN is an intermediate in the biosynthesis of nicotinamide adenine dinucleotide, or NAD+, a coenzyme involved in many metabolic reactions. The abbreviation usually refers to the beta anomer, though related forms can exist. In scientific literature, NMN is distinct from nicotinamide riboside, another NAD+ precursor.
In the NAD+ salvage pathway, the enzyme NAMPT converts nicotinamide and a phosphate-donor molecule into NMN. A second enzyme, NMNAT, then converts NMN into NAD+. Nicotinamide riboside can also enter this route after being converted to NMN by nicotinamide riboside kinases. Because NMN sits at a junction between precursor uptake and NAD+ formation, its cellular concentration is tightly linked to enzyme activity and tissue type. NAD+ participates in redox reactions, signaling, and DNA repair, and its levels decline with age in some animal models, though human evidence remains more limited and context-dependent.
Research interest in NMN increased after animal studies reported that oral or injected NMN can raise NAD+ levels in some tissues. How NMN is absorbed and distributed in humans is not fully established. Some evidence suggests extracellular NMN may be dephosphorylated to nicotinamide riboside before cellular uptake, while other studies propose specific transport routes. Direct human data on these mechanisms remain limited. Regulatory status also varies: in some countries NMN is treated as a dietary supplement, while elsewhere it is restricted or requires approval, and these differences affect labeling, sale, and research.
Analytical laboratories identify and quantify NMN using several complementary techniques. High-performance liquid chromatography with ultraviolet detection is widely used for purity and assay work. Liquid chromatography coupled to mass spectrometry provides greater sensitivity and is common for biological matrices. Nuclear magnetic resonance spectroscopy supports structural confirmation and can distinguish related nucleotides. Accurate measurement depends on reference standards, validated methods, and careful sample preparation, especially because NMN can convert to related compounds under some conditions.
Regulatory treatment of NMN varies by jurisdiction and has changed over time. Some countries allow it in dietary supplements, while others treat it as a novel food ingredient requiring safety review. In the United States, the Food and Drug Administration has questioned whether NMN can be lawfully marketed as a dietary supplement because of drug preclusion provisions. Sports organizations have separate rules, and NMN is not currently on the World Anti-Doping Agency prohibited list. These differences create uncertainty for manufacturers, retailers, and researchers seeking consistent legal pathways.
Nicotinamide mononucleotide is usually handled as a dry powder because moisture can promote hydrolysis and shorten shelf life. Recommended storage conditions often include a desiccated container at minus twenty degrees Celsius or colder, with protection from light. Aqueous solutions are less stable than solid material and may degrade faster at ambient temperature or neutral pH. Repeated freeze-thaw cycles can introduce variability, so aliquoting is common in laboratory settings. These practices reflect general nucleotide chemistry rather than a single universal protocol.
| Property | Value | Notes |
|---|---|---|
| Chemical name | Nicotinamide mononucleotide | Common name; beta form often denoted beta-NMN |
| Chemical formula | C11H15N2O8P | As free acid; salt forms differ |
| Molar mass | 334.22 g/mol | Calculated for the free acid |
| CAS Registry Number | 1094-61-7 | For beta-nicotinamide mononucleotide |
| Biochemical role | NAD+ intermediate | Participates in the salvage biosynthesis pathway |
Research on NMN has expanded because NAD+ concentrations decline with age in some tissues and because NAD+ participates in energy metabolism, DNA repair, and signaling. Animal studies have reported changes in NAD+ levels after NMN administration, but human data are more limited and often focus on safety, pharmacokinetics, and biomarker changes. Questions remain about oral absorption, tissue distribution, and whether changes in blood NAD+ reflect changes inside specific organs. NMN is not an approved drug, and claims about its clinical effects should be distinguished from established biochemical findings.
Nicotinamide mononucleotide, abbreviated NMN, is a naturally occurring nucleotide. Its structure combines a nicotinamide ring, a ribose sugar, and a phosphate group. The compound exists in cells as an intermediate in the production of nicotinamide adenine dinucleotide, a central redox cofactor. NMN is distinct from nicotinamide riboside, another related pyridine nucleotide, although the two compounds can converge in metabolic pathways. Its chemical formula is C11H15N2O8P, and it carries a net negative charge at physiological pH.
In the salvage pathway, NMN is generated from nicotinamide and 5-phosphoribosyl-1-pyrophosphate by the enzyme nicotinamide phosphoribosyltransferase. A second route produces NMN from nicotinamide riboside through phosphorylation by nicotinamide riboside kinases. NMN is then converted to NAD+ by nicotinamide mononucleotide adenylyltransferases, often called NMNAT enzymes. This stepwise route allows cells to recycle nicotinamide and maintain NAD+ levels under changing metabolic conditions. The relative contribution of each route varies by tissue, species, and physiological state, and it remains an active area of research.
Stability of NMN depends on physical form, temperature, moisture, light, and pH. The solid compound is generally more stable than aqueous solutions, which can degrade over time, especially when warm or exposed to extreme pH. Recommended laboratory storage is typically desiccated at −20 °C or below, protected from light, with containers sealed to limit moisture uptake. In solution, degradation products may include nicotinamide and related ribosides, and the rate varies with buffer composition and concentration. Analytical laboratories often prepare fresh solutions and validate stability for each method.
Quality control for NMN materials usually covers identity, assay purity, residual solvents, heavy metals, microbial limits, and moisture content. Certificates of analysis from suppliers may report high-performance liquid chromatography purity, mass spectrometry identity, and elemental impurity testing. Regulatory treatment differs by country: NMN is not an approved drug, and its status as a dietary supplement ingredient or novel food has been debated. Some authorities have restricted sales pending safety and regulatory review, while others allow it under specific categories. Buyers should verify documentation rather than rely on label claims.
Rendered unable to throw from his surgery, Bagwell was activated in September as a pinch hitter, and he played a symbolic role in the successful drive to capture their first-ever National League pennant and World Series appearance. Moreover, the Astros secured the pennant against their division rival St. Louis Cardinals in the NLCS, reversing the outcome from the year prior against the same club. After having played 4,714 games and their entire major league careers together in Houston, Bagwell and Biggio appeared in their first World Series in 2005. Bagwell was the Astros' designated hitter in the first two games against the White Sox at U.S. Cellular Field, and was a pinch hitter in the two games played in Houston at Minute Maid Park. His last official major league plate appearance was in the seventh inning of Game 4, when he pinch-hit for pitcher Brandon Backe and grounded out. The White Sox won this contest to sweep the Astros and secure the championship. The White Sox outscored the Astros by a combined six runs, the lowest scoring differential in World Series history. Together with Biggio, and longtime Astros executive Tal Smith, Bagwell received Baseball America's Lifetime Achievement Award after the 2005 season.
Most navies prohibited women from serving on submarines, even after they had been permitted to serve on surface warships. The Royal Norwegian Navy became the first navy to allow women on its submarine crews in 1985. The Royal Danish Navy allowed female submariners in 1988. Others followed suit including the Swedish Navy (1989), the Royal Australian Navy (1998), the Spanish Navy (1999), the German Navy (2001) and the Canadian Navy (2002). In 1995, Solveig Krey of the Royal Norwegian Navy became the first female officer to assume command on a military submarine, HNoMS Kobben. On 8 December 2011, British Defence Secretary Philip Hammond announced that the UK's ban on women in submarines was to be lifted from 2013. Previously there were fears that women were more at risk from a build-up of carbon dioxide in the submarine. But a study showed no medical reason to exclude women, though pregnant women would still be excluded. Similar dangers to the pregnant woman and her fetus barred women from submarine service in Sweden in 1983, when all other positions were made available for them in the Swedish Navy. Today, pregnant women are still not allowed to serve on submarines in Sweden. However, the policymakers thought that it was discriminatory with a general ban and demanded that women should be tried on their individual merits and have their suitability evaluated and compared to other candidates. Further, they noted that a woman complying with such high demands is unlikely to become pregnant. In May 2014, three women became the RN's first female submariners.
== External links == Fragrant Orchid: The Story of My Early Life - University of Hawaii Press Fragrant Orchid: The Story of My Early Life - University of British Columbia Press Copy of the book (DOI 10.1515/9780824854041) at DeGruyter Copy of the book at Project MUSE Copy of the book at JSTOR Book profile (of the English version) at CiNii
==== Role in cardiac hypertrophy and fibrosis ==== Intracrine Ang II has been implicated in the development of cardiac hypertrophy, a process characterized by the enlargement of cardiac myocytes in response to increased workload or stress. Experimental models have shown that overexpression of non-secreted Ang II in cardiac cells leads to rapid hypertrophy independent of extracellular Ang II signaling. This suggests that intracellular Ang II plays a direct role in cardiomyocyte growth and structural remodeling. Similarly, intracrine Ang II contributes to myocardial fibrosis by upregulating profibrotic cytokines and growth factors, such as transforming growth factor-beta (TGF-β) and platelet-derived growth factor (PDGF). This promotes the excessive deposition of extracellular matrix proteins, leading to stiffening of the cardiac tissue and impaired cardiac function.
Sources: en.wikipedia.org
== Formal oxidation states for pyrite, marcasite, molybdenite and arsenopyrite == From the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite and marcasite are probably best described as Fe2+[S2]2−. This formalism recognizes that the sulfur atoms in pyrite occur in pairs with clear S−S bonds. These persulfide [−S−S−] units can be viewed as derived from hydrogen disulfide, H2S2. Thus pyrite would be more descriptively called iron persulfide, not iron disulfide. In contrast, molybdenite, MoS2, features isolated sulfide S2− centers and the oxidation state of molybdenum is Mo4+. The mineral arsenopyrite has the formula FeAsS. Whereas pyrite has [S2]2− units, arsenopyrite has [AsS]3− units, formally derived from deprotonation of arsenothiol (H2AsSH). Analysis of classical oxidation states would recommend the description of arsenopyrite as Fe3+[AsS]3−.
Gone with the Wind—first released in 1939—is generally considered to be the most successful film, with Guinness World Records in 2014 estimating its adjusted global gross at $3.4 billion. Estimates for Gone with the Wind's adjusted gross have varied substantially: its owner, Turner Entertainment, estimated its adjusted earnings at $3.3 billion in 2007, a few years earlier than the Guinness estimate; other estimates fall either side of this amount, with one putting its gross just under $3 billion in 2010, while another provided an alternative figure of $3.8 billion in 2006. Which film is Gone with the Wind's nearest rival depends on the set of figures used: Guinness had Avatar in second place with $3 billion, while other estimates saw Titanic in the runner-up spot with first-run worldwide earnings of almost $2.9 billion at 2010 prices.
For example, if it is predicted that the transition state structure has a build-up of negative charge relative to the ground state structure, then electron-donating groups would be expected to increase the rate of the reaction. Other LFER scales have been developed. Steric and polar effects are analyzed through Taft Parameters. Changing the solvent instead of the reactant can provide insight into changes in charge during the reaction. The Grunwald-Winstein Plot provides quantitative insight into these effects.
==== Federal and large-scale ==== Several different organizations exist to mitigate and respond to food distribution crises in the United States. Prominent contributors to large-scale food distribution effort in the US include the Federal Emergency Management Agency (FEMA), United States Department of Agriculture (USDA), and Salvation Army. FEMA and the USDA work together during food distribution crises to coordinate the procurement and transportation of nonperishable food, water, and other resources to afflicted areas. The Salvation Army receives federal supplies from FEMA and the USDA, and then works on the local level to distribute necessary goods. All food given to civilians during a crisis is typically distributed at mass emergency feeding stations.
=== Water === Snow and ice sublime gradually at temperatures below the solid–liquid boundary (melting point) (generally 0 °C), and at partial pressures below the triple point pressure of 612 Pa (0.00604 atm), at a low rate. In freeze-drying, the material to be dehydrated is frozen and its water is allowed to sublime under reduced pressure or vacuum. The loss of snow from a snowfield during a cold spell is often caused by sunshine acting directly on the upper layers of the snow. Sublimation of ice is a factor to the erosive wear of glacier ice, known as ablation in glaciology.
Sources: en.wikipedia.org
Television broadcasting is the transmission of moving images along with a synchronized audio (sound) channel by radio. The sequence of still images is displayed on a screen on a television receiver (a "television" or TV), which includes a loudspeaker. Television (video) signals occupy a wider bandwidth than broadcast radio (audio) signals. Analog television, the original television technology, required 6 MHz, so the television frequency bands are divided into 6 MHz channels, now called "RF channels". Designations for television and FM radio broadcast frequencies vary between countries, see Television channel frequencies and FM broadcast band. Since VHF and UHF frequencies are desirable for many uses in urban areas, in North America some parts of the former television broadcasting band have been reassigned to cellular phone and various land mobile communications systems. Even within the allocation still dedicated to television, TV-band devices use channels without local broadcasters. The Apex band in the United States was a pre-WWII allocation for VHF audio broadcasting; it was made obsolete after the introduction of FM broadcasting. The current television standard, introduced beginning in 1998, is a digital format called high-definition television (HDTV), which transmits pictures at higher resolution, typically 1080 pixels high by 1920 pixels wide, at a rate of 50 or 60 interlaced fields/progressive frames per second.
There are biocompatible microalgae hybrid microrobots for active drug-delivery in the lungs and the gastrointestinal tract. The microrobots proved effective in tests with mice. In the two studies, "Fluorescent dye or cell membrane–coated nanoparticle functionalized algae motors were further embedded inside a pH-sensitive capsule" and "antibiotic-loaded neutrophil membrane-coated polymeric nanoparticles [were attached] to natural microalgae".
== Career == After completing his postdoctoral fellowship in France, in 1969, Watson returned the United States and held a position as an Assistant Professor in the Department of Pharmacology at Vanderbilt University, in Nashville Tennessee. Jack was promoted to Associate Professor with tenure in 1974. While at Vanderbilt, Watson published the first edition of Introduction to Mass Spectrometry: Biomedical, Environmental, and Forensic Applications in 1976. It was the first book to include journal titles as part of the cited literature. Harold G. (Harry) Walsh had just joined the ACS as director of the Short Course program. Walsh approached Watson and asked him to teach a course. Walsh also asked that Watson select someone from the mass spectrometry industry to co-teach the course. Watson had met O. David Sparkman, an American working for the French Gas Chromatography/Mass Spectrometry company, Riber, in Paris, a few months earlier. Watson asked Sparkman to contribute to the data systems part of the course. They taught the first session at the annual Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy in the Spring of 1978. They taught the course two more times that year at the annual ACS meetings and continued teaching into the first decade of the next millennium. In 1980 Watson accepted a joint appointment in the Departments of Biochemistry and Chemistry at Michigan State University, East Lansing Michigan. He also became the director (Principal Investigator) of the National Institutes of Health (NIH) P41 Regional Resource in Mass Spectrometry at MSU.
Molecular studies have revealed an unexpectedly large number of cryptic lichen species. Cryptic species are genetically distinct yet morphologically similar to other species. Because many lichens differ only subtly in form or chemistry, they harbour extensive cryptic diversity. Lumbsch and Leavitt (2011) termed this a paradigm shift: morphology alone often fails to delimit species. They reviewed numerous examples across lichenology. In the large foliose lichen genus Xanthoparmelia, eight morphospecies were merged after DNA showed they formed a single lineage. Conversely, lookalike Xanthoparmelia thalli fell into several distinct lineages, increasing species counts. Genetic work on the pantropical Cladia aggregata complex uncovered at least 11 distinct species within what had been treated as one. A phylogenomic survey of the cosmopolitan granite‑dweller Lecanora polytropa pushed this pattern to the extreme, recovering up to 75 evolutionarily independent lineages within what had long been treated as a single species—about a seventy‑fold jump in recognized diversity. Such cases show that traditional concepts both lumped and split species incorrectly. Characters like growth form, colour, or the presence/absence of sexual structures (such as whether a lichen reproduces by spores or is sterile and reproduces only asexually by fragments) were often over-weighted and do not always track evolutionary lineages.
Sources: en.wikipedia.org
Nicotinamide mononucleotide is a nucleotide intermediate in the biosynthesis of NAD+. It consists of nicotinamide attached to a ribose phosphate unit. NMN occurs naturally in cells and is present at low levels in some foods.
NMN is a direct precursor in the NAD+ salvage pathway. Enzymes called NMNAT convert NMN into NAD+, a coenzyme used in metabolism and cell signaling. Raising NMN may increase NAD+ in some experimental settings, but the effect depends on tissue and organism.
No. Nicotinamide riboside is a related compound that lacks the phosphate group present in NMN. Cells can convert nicotinamide riboside into NMN, and both compounds feed into NAD+ production through overlapping routes.
Solid NMN is often kept cool, dry, and protected from light. Long-term storage may use temperatures at or below minus twenty degrees Celsius. Moisture and repeated temperature changes should be avoided.