The short version of HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-04 and is reviewed periodically as new material appears.
Identity and purity are usually assessed with complementary methods. Nuclear magnetic resonance spectroscopy can confirm the molecular structure and distinguish anomeric forms. High-performance liquid chromatography with ultraviolet detection or mass spectrometry is common for assay and related-substance testing. Mass spectrometry also supports trace quantification in biological samples, often with isotope-labeled internal standards. Because NMN lacks a strong chromophore, some ultraviolet methods require careful wavelength selection or derivatization, and laboratories may validate each approach for its intended matrix.
Commercial NMN is produced through enzymatic or chemical routes, and the resulting material can vary in purity, counterion, and residual solvent content. Buyers typically rely on certificates of analysis, but independent verification through third-party laboratories provides stronger assurance. Regulatory treatment differs by country; in the United States, NMN has been subject to shifting guidance about its status as a dietary supplement, while other markets permit sales under local rules. No universal pharmacopeial monograph exists for NMN, so specifications often come from suppliers, research protocols, or regional requirements.
Chemically, NMN is described by the molecular formula C11H15N2O8P and a molecular mass near 334.22 g/mol. The beta anomer has a CAS Registry Number of 1094-61-7. It is typically supplied as a white to off-white powder for laboratory use. The molecule carries a phosphate group and a positively charged nicotinamide ring, giving it polar and water-soluble character. These properties influence how it is detected, purified, and stored in research and analytical laboratories.
Nicotinamide mononucleotide, abbreviated NMN, is a nucleotide composed of nicotinamide, ribose, and phosphate. Its structure links nicotinamide to D-ribose 5-phosphate through a glycosidic bond, placing it in the pyridine nucleotide family. The compound exists in alpha and beta anomeric forms, and the beta form is the one used in NAD+ biosynthesis. NMN is not a protein or a hormone; it is a small water-soluble molecule that occurs in living cells as a metabolic intermediate.
Natural sources of NMN include mammals, plants, and microorganisms, where it functions as an intermediate in NAD+ salvage and biosynthesis pathways. In mammals, the enzyme nicotinamide phosphoribosyltransferase produces NMN from nicotinamide and phosphoribosyl pyrophosphate. NMN is then converted to NAD+ by nicotinamide mononucleotide adenylyltransferase. Some foods contain measurable NMN, but reported amounts vary widely by species, tissue, and analytical method. The extent to which dietary NMN contributes to cellular NAD+ pools remains an open research question.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | −20 °C or below | Dry, desiccated, protected from light |
| Aqueous solubility | High | Stability is pH- and temperature-dependent |
| Identity method | NMR spectroscopy | Confirms structure and anomeric form |
| Purity method | HPLC-UV or LC-MS | Measures assay and related substances |
| Common salt forms | Free acid; sodium salt | Counterion changes mass and hygroscopicity |
Friendly AI are machines that have been designed from the beginning to minimise risks and to make choices that benefit humans. Eliezer Yudkowsky, who coined the term, argues that developing friendly AI should be a higher research priority: it may require a large investment and it must be completed before AI becomes an existential risk. Machines with intelligence have the potential to use their intelligence to make ethical decisions. The field of machine ethics provides machines with ethical principles and procedures for resolving ethical dilemmas. The field of machine ethics is also called computational morality, and was founded at an AAAI symposium in 2005. Geoffrey Hinton has suggested researchers explore instilling human-aligned values, such as compassion, into AI systems as a safeguard, speculating about the possibility of building "maternal instincts" into AI models, so “they really care about people”. Other approaches include Wendell Wallach's "artificial moral agents" and Stuart J. Russell's three principles for developing provably beneficial machines.
(2026) study the visibility of fallow deer in broad-leaved woodland environment, and interpret purported hunting lesions on fossil bones of fallow deer as placed in areas that would be visible to Palaeolithic hunters in such environments. Evidence indicating that Aurignacian artifacts from cave sites in southwestern Germany were adorned with geometric sign sequences of comparable complexity to that of early proto-cuneiform is presented by Bentz & Dutkiewicz (2026). Conard, Janas & Zeidi (2026) report the discovery of two Aurignacian bird figurines made from mammoth ivory in the Hohle Fels cave (Germany). Isle de Beauchaine et al. (2026) study the morphology of teeth in the Aurignacian mandible Les Rois 2 from the Les Rois cave (Charente, France), interpreted as consistent with assignment of the specimen to an anatomically modern human. Röding et al. (2026) study the morphology of the Late Pleistocene frontal bone from Hahnöfersand (Germany) described by Bräuer (1980), interpret it as falling within the variability of Holocene Homo sapiens, and find no evidence of a morphology intermediate between those of Neanderthals and modern humans. Bossoms Mesa et al. (2026) report evidence of preservation of human DNA in pigment samples collected in and around Paleolithic rock art, including preservation of DNA resulting from deposition through direct human contact in the Escoural Cave (Portugal).
In the 1700s, a Swiss gynecologist, Peyer, published a description of a cystocele. He was able to describe and document both cystoceles and uterine prolapse. In 1730, Halder associated cystocele with childbirth. During this same time, efforts began to standardize the terminology that is still familiar today. In the 1800s, the surgical advancements of anesthesia, suturing, suturing materials, and acceptance of Joseph Lister's theories of antisepsis improved outcomes for women with cystocele. The first surgical techniques were practiced on female cadavers. In 1823, Geradin proposed that an incision and resection may provide treatment. In 1830, the first dissection of the vagina was performed by Dieffenbach on a living woman. In 1834, Mendé proposed that dissecting and repairing the edges of the tissues could be done. In 1859, Huguier proposed that the amputation of the cervix was going to solve the problem of elongation. In 1866, a method of correcting a cystocele was proposed that resembled current procedures. Sim subsequently developed another procedure that did not require the full-thickness dissection of the vaginal wall. In 1888, another method of treating anterior vaginal wall Manchester combined an anterior vaginal wall repair with an amputation of the cervix and a perineorrhaphy. In 1909, White noted the high rate of recurrence of cystocele repair. At this time it was proposed that reattaching the vagina to support structures was more successful and resulted in less recurrence.
=== Rest period === The rest period is defined as the time dedicated to recovery between sets and exercises. Exercise causes metabolic stress, such as the buildup of lactic acid and the depletion of adenosine triphosphate and phosphocreatine. Resting 3–5 minutes between sets allows for significantly greater repetitions in the next set versus resting 1–2 minutes. For untrained individuals (no previous resistance training experience), the effect of resting on muscular strength development is small and other factors such as volitional fatigue and discomfort, cardiac stress, and the time available for training may be more important. Moderate rest intervals (60-160s) are better than short (20-40 s), but long rest intervals (3–4 minutes) have no significant difference from moderate. For trained individuals, rest of 3–5 minutes is sufficient to maximize strength gain, compared to shorter intervals 20s-60s and longer intervals of 5 minutes. Intervals of greater than 5 minutes have not been studied. Starting at 2 minutes and progressively decreasing the rest interval over the course of a few weeks to 30s can produce similar strength gains to a constant 2 minutes. Regarding older individuals, a 1-minute rest is sufficient in females.
==== Albums ==== Butterfly Love (Boner Records, 1989) Lurch (Boner Records, 1990) Tulip (Boner Records, 1990) The Miracle of Sound in Motion (Boner Records, 1993) Your Choice Live Series 019 (Your Choice Records, 1993) Best of Steel Pole Bathtub (Sento, 1993) Scars from Falling Down (Slash/London, 1995) Unlistenable (Zero to One, 2002)
Sources: en.wikipedia.org
Sharpey's fibres (bone fibres, or perforating fibres) are a matrix of connective tissue consisting of bundles of strong predominantly type I collagen fibres connecting periosteum to bone. They are part of the outer fibrous layer of periosteum, entering into the outer circumferential and interstitial lamellae of bone tissue. Sharpey's fibres also attach muscle to the periosteum of bone by merging with the fibrous periosteum and underlying bone as well. A good example is the attachment of the rotator cuff muscles to the blade of the scapula. In the teeth, Sharpey's fibres are the terminal ends of principal fibres (of the periodontal ligament) that insert into the cementum and into the periosteum of the alveolar bone. A study on rats suggests that the three-dimensional structure of Sharpey's fibres intensifies the continuity between the periodontal ligament fibre and the alveolar bone (tooth socket), and acts as a buffer medium against stress. Sharpey's fibres in the primary acellular cementum are mineralized fully; those in cellular cementum and bone are mineralized only partially at their periphery. In the skull, the main function of Sharpey's fibres is to bind the cranial bones in a firm but moveable manner; they are most numerous in areas where the bones are subjected to the greatest forces of separation. In the spine, similar fibres join the intervertebral disc to the adjacent vertebrae. Each fibre is accompanied by an arteriole and one or more nerve fibres.
== Mode of action == It is believed that ω-grammotoxin SIA inhibits channel function by binding with high affinity to closed, resting states of the channel and that bound toxin makes it more difficult for channels to be opened by depolarization, so much larger depolarizations are required for channel activation.
Beginning in 1852 with a passing mention in Charles Dickens' Bleak House, dinosaurs have been featured in large numbers of fictional works. Jules Verne's 1864 novel Journey to the Center of the Earth, Sir Arthur Conan Doyle's 1912 book The Lost World, the 1914 animated film Gertie the Dinosaur (featuring the first animated dinosaur), the iconic 1933 film King Kong, the 1954 Godzilla and its many sequels, the best-selling 1990 novel Jurassic Park by Michael Crichton and its 1993 film adaptation are just a few notable examples of dinosaur appearances in fiction. Authors of general-interest non-fiction works about dinosaurs, including some prominent paleontologists, have often sought to use the animals as a way to educate readers about science in general. Dinosaurs are ubiquitous in advertising; numerous companies have referenced dinosaurs in printed or televised advertisements, either in order to sell their own products or in order to characterize their rivals as slow-moving, dim-witted, or obsolete.
== History == SCIEX was founded in 1974 by Canadian scientists Barry French, Neil Reid, Adele Buckley, and businessman William Breukelman, to develop a mass spectrometer system based on atmospheric pressure ionisation and direct air sampling. In 1981, SCIEX was acquired by MDS Inc., a Canadian medical services and equipment company. A joint venture was formed with PerkinElmer for sales and marketing of the inductively coupled plasma mass spectrometry (ICPMS) product line. In 1986, the joint venture was extended to include the liquid chromatography–mass spectrometry (LC/MS) business, managed through the Applied Biosystems division of Perkin Elmer. In 2008, Applied Biosystems merged with Invitrogen to form Life Technologies. In 2009, Danaher Corporation paid approximately $1.1 billion to buy SCIEX from MDS and the Applied Biosystems/MDS SCIEX joint venture business from Life Technologies. The business unit now operates as SCIEX within the Life Sciences Division of Danaher and is one of the major players in the global mass spectrometry market estimated (in 2018) at $5.5 billion worldwide.
=== Porosity === Porosity is defined as volume fraction of voids within the PS layer and can be determined easily by weight measurement. The porosity of PS may range from 4% for macroporous layers to 95% for mesoporous layers. A study by Canham in 1995 found that "a 1 μm thick layer of high porosity silicon completely dissolved within a day of in-vitro exposure to a simulated body fluid". It was also found that a silicon wafer with medium to low porosity displayed more stability. Hence, the porosity of PS is chosen according to its potential application areas. The porosity of PS is a macroscopic parameter and doesn't yield any information regarding the microstructure of the layer. It is proposed that the properties of a sample are more accurately predicted if the pore size and pore distribution within the sample can be obtained.
Sources: en.wikipedia.org
Purity is commonly measured by high-performance liquid chromatography with ultraviolet or mass spectrometric detection. Nuclear magnetic resonance can confirm identity and anomeric composition. Water content and residual solvents may be tested separately.
Dry NMN is typically stored refrigerated or frozen in a desiccated container. Solutions are less stable and should be kept cold and used promptly. Protection from light and moisture helps limit degradation.
Beta-NMN is the naturally occurring anomer involved in NAD+ production. Alpha-NMN can form during synthesis and is often tracked as an impurity. Analytical methods such as NMR or HPLC can distinguish the two forms.
NMN stands for nicotinamide mononucleotide. It is a naturally occurring nucleotide and an intermediate in NAD+ biosynthesis.