This is a working overview of Mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-20. Anything still debated is marked as such rather than presented as settled.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Freeze-dried solid |
| Solubility class | Freely soluble in water | Aqueous buffers also suitable |
| Typical storage temperature | Minus 20 degrees Celsius or colder | Desiccated and light protected |
| Typical analytical method | RP-HPLC with UV detection | 214 nm on C18 column |
| Identity confirmation | Electrospray mass spectrometry | Sequence verified separately |
Lidocaine/prilocaine is a topical anesthesia which can be used to numb the skin for medical or cosmetic purposes; it is a eutectic mixture of equal quantities (by weight) of lidocaine and prilocaine. A 5% emulsion preparation, containing 2.5% each of lidocaine/prilocaine, is marketed by APP Pharmaceuticals under the trade name EMLA (an abbreviation for Eutectic Mixture of Local Anesthetics). As a spray, it is marketed under the name Tempe (topical eutectic-like mixture for premature ejaculation) (PSD502) that can be used by men to help with premature ejaculation. The spray is manufactured by Plethora Solutions and branded as Fortacin in the UK and Recordati in the EU.
=== 1964 === January 12: the Arab-dominated government of the Zanzibar Sultanate is overthrown by John Okello, establishing the new people's republic. The new regime orders a massacre against minorities, resulting in the deaths of hundred to thousand Arabs and South Asians in Zanzibar. January 27: France recognizes the People's Republic of China. The Republic of China severs diplomatic relations with France on February 10. March 31–April 1: A military-led coup d'état overthrows president João Goulart in Brazil. Goulart's proposals, such as land reform and bigger control of the state in the economy, were seen as communist. April 20: U.S. President Lyndon Johnson in New York, and Soviet First Secretary Nikita Khrushchev in Moscow, announce simultaneously plans to cut back production of materials for making nuclear weapons. May 27: Jawaharlal Nehru dies. The Colombian conflict begins. July 4: The Rhodesian Bush War begins when African nationalist / Marxist insurgents rebel against colonial rule in Rhodesia (modern-day Zimbabwe). Nyasaland (renamed Malawi upon independence) becomes independent from the UK. August 4: U.S. President Lyndon B. Johnson claims that North Vietnamese naval vessels had fired on two American destroyers in the Gulf of Tonkin. Although there was a first attack, it was later shown that American vessels had entered North Vietnamese territory first, and that the claim of second attack had been unfounded. The Gulf of Tonkin incident leads to the open involvement of the United States in the Vietnam War, after the Gulf of Tonkin Resolution.
Camouflage does not always fool a predator. When caught out, snake species adopt different defensive tactics and use a complicated set of behaviors when attacked. Some species, like cobras or hognose snakes, first elevate their head and spread out the skin of their neck in an effort to look large and threatening. Failure of this strategy may lead to other measures practiced particularly by cobras, vipers, and closely related species, which use venom to attack. The venom is modified saliva, delivered through fangs from a venom gland. Some non-venomous snakes, such as American hognose snakes or European grass snake, play dead when in danger; some, including the grass snake, exude a foul-smelling liquid to deter attackers.
Banting's namesake, the Banting Research Foundation, was created in 1925 and provides funding to support health and biomedical research in Canada. Banting's name is immortalized in the yearly Banting Lectures, given by an expert in diabetes, and by the creation of the Banting and Best Department of Medical Research of the University of Toronto; Sir Frederick G Banting Research Centre located on Sir Frederick Banting Driveway in the Tunney's Pasture complex, Ottawa; Banting Memorial High School in Alliston Sir Frederick Banting Secondary School in London, Ontario; Sir Frederick Banting Alternative Program Site in Ottawa; Frederick Banting Elementary School in Montréal-Nord and École Banting Middle School in Coquitlam. The "Major Sir Frederick Banting, MC, RCAMC Award for Military Health Research", sponsored by the True Patriot Love Foundation, is awarded annually by the Surgeon General to the researcher whose work presented at the annual Military and Veterans Health Research Forum is deemed to contribute most to military health. It was first awarded in 2011 in the presence of several Banting descendants. The "Canadian Forces Major Sir Frederick Banting Term Chair in Military Trauma Research" at Sunnybrook Health Sciences Centre was established in 2012. The first Chair holder is Colonel Homer Tien, medical director of Sunnybrook's Tory Regional Trauma Centre and Senior Specialist and Trauma Adviser to the Surgeon General.
=== Modern corals === The currently ubiquitous stony corals, Scleractinia, appeared in the Middle Triassic to fill the niche vacated by the extinct rugose and tabulate orders and is not closely related to the earlier forms. Unlike the corals prevalent before the Permian extinction, which formed skeletons of a form of calcium carbonate known as calcite, modern stony corals form skeletons composed of aragonite. Their fossils are found in small numbers in rocks from the Triassic period, and become common in the Jurassic and later periods. Although they are geologically younger than the tabulate and rugose corals, the aragonite of their skeletons is less readily preserved, and their fossil record is accordingly less complete.
Sources: en.wikipedia.org
==== Sensitivity to erosion ==== Stream power has also been used as a criterion to determine whether a river is in a state of reshaping itself or whether it is stable. A value of unit stream power between 30 and 35 W m−2 in which this transition occurs has been found by multiple studies. Another technique gaining popularity is using a gradient of stream power by comparing the unit stream power upstream to the local unit stream power (
== Early life == Carlisle was selected by Essendon with pick 24 in the 2009 National Draft. Like fellow draftee Jake Melksham, he is a local to the Essendon area. He played with the Calder Cannons in the TAC Cup and Craigieburn in the EDFL. He represented Vic Metro in the 2009 AFL National Under 18 Championships and was part of the 2009 Premiership team.
== Uses == Blasticidin S is widely used in cell culture for selecting and maintaining genetically manipulated cells. Cells of interest express the blasticidin S resistance genes BSD or bsr, and can then survive blasticidin S being added to the culture media. Blasticidin S is typically used at 2–300 micrograms per milliliter of media, depending on the type of cell being grown.
Though the aggregate concentration may not be calculated with light scattering (an online concentration detector such as that used in SEC-MALS for molar mass measurement also determines aggregate concentration), the size of the aggregate can be measured, only limited by the maximum size eluting from the SEC columns. Limitations of ASEC with DLS detection include flow-rate, concentration, and precision. Because a correlation function requires anywhere from 3–7 seconds to properly build, a limited number of data points can be collected across the peak. ASEC with SLS detection is not limited by flow rate and measurement time is essentially instantaneous, and the range of concentration is several orders of magnitude larger than for DLS. However, molar mass analysis with SEC-MALS does require accurate concentration measurements. MALS and DLS detectors are often combined in a single instrument for more comprehensive absolute analysis following separation by SEC.
== People == Maxim (given name) Maxim (surname) Maxim (musician) Maxim., taxonomic author abbreviation of Karl Maximovich (1827–1891), Russian botanist Maksim, Metropolitan of all Rus, Metropolitan of Kiev (1283–1305) Maksim, Bulgarian Patriarch (1914–2012), Patriarch of the Bulgarian Orthodox Church Maksim, Serbian Patriarch (d. 1680), Patriarch of the Serbian Orthodox Church (1655-1674) Maksim Branković (d. 1516), Serbian Orthodox Metropolitan of Belgrade and Syrmia
Sources: en.wikipedia.org
This can happen, for example, when a recombinant DNA fragment containing an active promoter becomes located next to a previously silent host cell gene, or when a host cell gene that functions to restrain gene expression undergoes insertional inactivation by recombinant DNA.
The first 16 months of the MD program, the preclerkship phase, consists of fundamental scientific and medical coursework. Multi-semester courses include bioethics and service learning. This is followed by a 12-month clinical phase that includes clerkships and preparation for and completion of the United States Medical Licensing Examination (USMLE) Step 1. Clerkships are followed by completion of the USMLE Step 2 exam. The final 18 months of medical school include clinical electives, increased clinical duties, and a research capstone project. In addition to Jacobi and Montefiore hospitals, medical students can train in medical facilities such as the VA Bronx Healthcare System and Bronx Psychiatric Center. Students may also volunteer at the Einstein Community Health Outreach (ECHO) Free Clinic, which provides care to those without health insurance. Founded in 1999, ECHO was the first such clinic in New York City and one of the first in the United States.
Many of Pauling's critics, including scientists who appreciated the contributions that he had made in chemistry, disagreed with his political positions and saw him as a naïve spokesman for Soviet communism. In 1960, he was ordered to appear before the Senate Internal Security Subcommittee, which termed him "the number one scientific name in virtually every major activity of the Communist peace offensive in this country". A headline in Life magazine characterized his 1962 Nobel Prize as "A Weird Insult from Norway". Pauling was a frequent target of the National Review magazine. In an article entitled "The Collaborators" in the magazine's July 17, 1962, issue, Pauling was referred to not only as a collaborator, but as a "fellow traveler" of proponents of Soviet-style communism. In 1963, Pauling sued the magazine, its publisher William Rusher, and its editor William F. Buckley, Jr for $1 million. He lost both his libel suits and the 1968 appeal (unlike his earlier 1963 libel case against the Hearst Corporation), because in the meantime the landmark case New York Times Co. v. Sullivan had established the actual malice standard for libel lawsuits by public figures, requiring that not only falsehood but deliberate lying should be proved by the plaintiff in such cases. His peace activism, his frequent travels, and his enthusiastic expansion into chemical-biomedical research all aroused opposition at Caltech. In 1958, the Caltech Board of Trustees demanded that Pauling step down as chairman of the Chemistry and Chemical Engineering Division.
=== Astina/323F === A sporty, five-door liftback version was called the Familia Astina in Japan. In other markets, it was called 323F and 323 Astina. A luxury version was also sold in Japan as the Eunos 100. The car was produced from 1989 until 1994 before being replaced by the Lantis. A key feature of the Astina/323F is the front end with its pop-up headlights. Depending on the market, there were carbureted or fuel injected SOHC/DOHC versions available of the 1.5, 1.6 and 1.8 L petrol engines. Unlike the standard Familia saloons and three-door hatchback, the Astina never came from the factory with a turbo, diesel or all-wheel drive option. Taillight arrangement varies from market to market, the main difference being the third brake light in the spoiler and two brake lights per cluster (Japanese spec), rather than one. Compared to the Eunos 100, the Familia Astina has some differences, such as a different trunk garnish, a shorter spoiler, available with SOHC engine options, and lacked the optional digital speedometer. In the UK the 323F was launched with 1.6 L 16-valve in either LX, GLX or GLXi trim or as 1.8i 16v GT. In Indonesia it is called Astina GT and RX3 (a special model featured aero kits), it came standard with a 1.8 L DOHC BP engine and a digital speedometer from the JDM Eunos 100. The 323 Astina GLX was sold in South America as well, specifically in Colombia, Chile and Argentina, with 1.6 L SOHC engine, in carbureted version.
After Deadline's failure, Platt avoided work on television until he read a script for The West Wing and signed on for a guest role. He received an Emmy nomination for his portrayal of no-nonsense White House Counsel Oliver Babish, brought in during season two to compile a defense for President Bartlet and others who covered up his non-disclosure of multiple sclerosis. His role in the television series Huff as Russell Tupper from 2004 to 2006 was well-received, especially by creator Bob Lowry, who said, "Oliver plays an alcoholic, drug-addicted, sexaholic, workaholic, womanizing misogynist who is adorable. I don't know any actor who could do that. I originally saw Russell as a blond stud, but when I saw what Oliver could do, I realized how much better, richer, and less predictable he was than my idea of the character ... Oliver is very committed to the idea that story and dialogue be character-driven and unique". Platt's work was nominated for two Emmy awards and a Golden Globe. In 2005, Platt acted in Harold Ramis's film The Ice Harvest as an unhappy businessman with a trophy wife and two stepchildren who becomes involved with a friend who has stolen $2 million from a Mafia boss. He also played a lard merchant named Papprizzio in Lasse Hallström's Casanova, who competes with Casanova (Heath Ledger) for marriage to Francesca (Sienna Miller). Platt won the New York Film Critics Online Award for best supporting actor for his role in Casanova.
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.
Aspartate can cyclise into a succinimide intermediate that later hydrolyses back as isoaspartate. Both forms share the same molecular mass, so mass spectrometry alone cannot tell them apart. This shapes how purity data should be interpreted.
Freeze-dried material is normally kept desiccated below minus twenty degrees Celsius and shielded from light. Solutions are prepared shortly before use and held cold. Repeated thawing is avoided because it accelerates aggregation and degradation.
The molecule lacks aromatic residues, so it absorbs weakly near 280 nanometres, the wavelength applied to many other peptides. The peptide bond absorbs strongly below 220 nanometres, making 214 nanometres a practical compromise. Gradient methods must therefore use mobile phases with low ultraviolet absorbance to keep the baseline clean.