Pro-Gly-Pro tail raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-03-18. Anything still debated is marked as such rather than presented as settled.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
and Afghan National Army soldiers led by SSG Robert James Miller was conducting a combat reconnaissance patrol through the Gowardesh Valley, Kunar Province, when they engaged a force of 15–20 insurgents occupying prepared fighting positions. After calling in close air support, Staff Sergeant Miller led a small squad forward to conduct battle damage assessment when over 100 insurgents ambushed the squad, Miller displayed extraordinary valor by drawing fire away from his squad, killing 10 insurgents in the process. His actions cost him his life, but he saved the lives of 7 members of his team and 15 Afghan National Army soldiers, he was awarded the Medal of Honor. In September 2008, a Green Beret ODA conducted a joint operation with 1 Troop 3 Squadron SASR in northwest Uruzgan Province, the operation was designed to lure insurgents into a trap using a ground convoy of five special forces GMV trucks as bait. SASR sniper teams, who inserted on foot the night before as part of two cut-off groups to overwatch the patrol. The plan worked, a small group of insurgents approached the vehicles, intent on ambushing the convoy, they were engaged by the SASR snipers. Minutes later a Toyota Hilux appeared carrying a number of armed insurgents, they were engaged and killed and a second vehicle, a van, arrived carrying 3 insurgents were engaged by the sniper teams until they spotted a female non-combatant who was used as a human shield by the surviving insurgent, the insurgent was eventually killed with no harm to the woman, a total of 13 insurgents were killed.
The competitor either withdraws or responds with a tail splash of its own. Usually, one or two splashes are exchanged per shark, though individuals will sometimes persist with more. The contest is "won" by the shark that compels the other to concede via the most tenacious splashing, which appears to signal strength and vigor. Larger body size does not always secure superior signal strength; on occasion, the smaller shark emerges victorious. White sharks have also been observed employing tail splashing to intimidate tiger sharks around a whale carcass and even against boats and shark cages, which were likely perceived as competitors.
The lower the barrier and the masses of the fragments, the greater the probability per unit time of a split. Protons in a nucleus are bound together by the strong force, which counterbalances the Coulomb repulsion between positively charged protons. In heavier nuclei, larger numbers of uncharged neutrons are needed to reduce repulsion and confer additional stability. Even so, as physicists started to synthesize elements that are not found in nature, they found the stability decreased as the nuclei became heavier. Thus, they speculated that the periodic table might come to an end. The discoverers of plutonium (element 94) considered naming it "ultimium", thinking it was the last. Following the discoveries of heavier elements, of which some decayed in microseconds, it then seemed that instability with respect to spontaneous fission would limit the existence of heavier elements. In 1939, an upper limit of potential element synthesis was estimated around element 104, and following the first discoveries of transactinide elements in the early 1960s, this upper limit prediction was extended to element 108.
Sindone.org – official site of the custodians of the shroud in Turin Professor Creates 3D Image From Shroud The Shroud of Turin Website – Shroud of Turin Education and Research Association, Inc. website Turin Shroud Center of Colorado – research center of John Jackson, a leading member of the STURP team Good Science, Bad Science, and the Shroud of Turin – 2014 NYUAD Chemistry lecture on YouTube Unwrapping the Shroud – 2009 Discovery channel documentary on YouTube Shroud of Turin Evidence – 2008 BBC documentary on YouTube Barrie Schwortz interview – EWTN interview with photographer Barrie Shwortz on YouTube
In the late 1970s and, particularly, during the early 1980s under U.S. President Ronald Reagan, the United States renewed its commitment to a more powerful military, which required a large increase in spending on U.S. military programs. These programs, which were originally part of the defense budget of U.S. President Jimmy Carter, included spending on conventional and nuclear weapons systems. Under Reagan, defensive systems like the Strategic Defense Initiative were emphasized as well. Another major shift in nuclear doctrine was the development and the improvement of the submarine-launched, nuclear-armed, ballistic missile, or SLBM. It was hailed by many military theorists as a weapon that would make nuclear war less likely. SLBMs—which can move with "stealth" (greatly lessened detectability) virtually anywhere in the world—give a nation a "second strike" capability (i.e., after absorbing a "first strike"). Before the advent of the SLBM, thinkers feared that a nation might be tempted to initiate a first strike if it felt confident that such a strike would incapacitate the nuclear arsenal of its enemy, making retaliation impossible. With the advent of SLBMs, no nation could be certain that a first strike would incapacitate its enemy's entire nuclear arsenal. To the contrary, it would have to fear a near-certain retaliatory second strike from SLBMs. Thus, a first strike was a much less feasible (or desirable) option, and a deliberately initiated nuclear war was thought to be less likely to start.
Sources: en.wikipedia.org
Some symptoms attributable to allergic diseases are mentioned in ancient sources. Particularly, three members of the Roman Julio-Claudian dynasty (Augustus, Claudius and Britannicus) are suspected to have a family history of atopy. The concept of "allergy" was originally introduced in 1906 by the Viennese pediatrician Clemens von Pirquet, after he noticed that patients who had received injections of horse serum or smallpox vaccine usually had quicker, more severe reactions to second injections. Pirquet called this phenomenon "allergy" from the Ancient Greek words ἄλλος allos meaning "other" and ἔργον ergon meaning "work". All forms of hypersensitivity were previously classified as allergies, and all were thought to be caused by an improper activation of the immune system. Later, it became clear that several disease mechanisms were implicated, with a common link to disordered immune system activation. In 1963, a new classification scheme was designed by Philip Gell and Robin Coombs that described four types of hypersensitivity reactions, known as Type I to Type IV hypersensitivity. With this new classification, the word allergy, sometimes clarified as a true allergy, was restricted to type I hypersensitivities (also called immediate hypersensitivity), which are characterized as rapidly developing reactions involving IgE antibodies. A breakthrough in understanding the mechanisms of allergy was the discovery of the antibody class labeled immunoglobulin E (IgE).
Quantitative studies of enzymatic reactions often found that the acceleration of chemical reaction speed cannot be fully explained by existing theories like the approximation, acid/base catalysis and electrophile/nucleophile catalysis. And there is an obvious paradox: in reversible enzymatic reaction if the active site perfectly fits the substrates then the backward reaction will be slowed since products cannot fit perfectly into the active site. So conformational distortion was introduced and argues that both active site and substrate can undergo conformational changes to fit with each other all the time.
Nickel-60 is the daughter product of the extinct radionuclide 60Fe (half-life 2.62 My). Because 60Fe has such a long half-life, its persistence in materials in the Solar System at high enough concentrations may have generated observable variations in the isotopic composition of 60Ni. Therefore, the abundance of 60Ni in extraterrestrial material may provide insight into the origin of the Solar System and its early history/very early history. Unfortunately, nickel isotopes appear to have been heterogeneously distributed in the early Solar System. Therefore, so far, no actual age information has been attained from 60Ni excesses. 60Ni is also the stable end-product of the decay of 60Zn, the last rung of the alpha ladder.
==== United States ==== The price of insulin in the United States dramatically increased from 1991 to 2019, prompting state governments to sue pharmaceutical companies over alleged price fixing. In 2019, the House Committee on Energy and Commerce questioned how the annual cost of insulin for treating Type 1 diabetes rose to $5,705 by 2019 ($7,184 in 2025), which was up to six times higher than prices in other countries. In 2020, President Donald Trump established the Part D Senior Savings Model for some Medicare Part D plans to offer insulin at $35 or less per month. In 2022, President Joe Biden signed the Inflation Reduction Act, requiring all Part D plans to adopt this price ceiling and cost sharing under Medicare Part B to follow the same threshold. In 2022, California allocated $100 million for the state to create its own insulin at a close-to-cost price.
Sources: en.wikipedia.org
The final withdrawal of the Mustang from USAF placed hundreds of P-51s onto the civilian market. The rights to the Mustang design were purchased from North American by the Cavalier Aircraft Corporation, which attempted to market the surplus Mustang aircraft in the US and overseas. In 1967 and again in 1972, the USAF procured batches of remanufactured Mustangs from Cavalier, most of them destined for air forces in South America and Asia that were participating in the Military Assistance Program (MAP). These aircraft were remanufactured from existing original F-51D airframes fitted with new V-1650-7 engines, a new radio, tall F-51H-type vertical tails, and a stronger wing that could carry six 12.7 mm (0.50 in) machine guns and a total of eight underwing hardpoints. Two 1,000-pound (450 kg) bombs and six 127 mm (5 in) rockets could be carried. They all had an original F-51D-type canopy but carried a second seat for an observer behind the pilot. One additional Mustang was a two-seat, dual-control TF-51D (67-14866) with an enlarged canopy and only four wing guns. Although these remanufactured Mustangs were intended for sale to South American and Asian nations through the MAP, they were delivered to the USAF with full USAF markings. They were, however, allocated new serial numbers (67-14862/14866, 67-22579/22582 and 72-1526/1541). The last US military use of the F-51 was in 1968 when the US Army employed a vintage F-51D (44-72990) as a chase aircraft for the Lockheed YAH-56 Cheyenne armed helicopter project.
Rhodium ores are a mixture with other metals such as palladium, silver, platinum, and gold. Few rhodium minerals are known. The separation of rhodium from the other metals poses significant challenges. Principal production is located in South Africa, at 75%, with much less production in Russia and Zimbabwe. The annual world production flucuates around 30 tonnes. The price of rhodium (per troy ounce) is highly variable, ranging from less than US$700.00 in 2016 to nearly US$30,000.00 in 2021.
=== Mechanism of action === Pazopanib is a multiple kinase inhibitor that limits tumor growth by targeting angiogenesis via inhibition of enzymes including vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), c-KIT and FGFR.
=== Investigations regarding tipping points === The ENSO is considered to be a potential tipping element in Earth's climate. Global warming can strengthen the ENSO teleconnection and resulting extreme weather events. For example, an increase in the frequency and magnitude of El Niño events have triggered warmer than usual temperatures over the Indian Ocean, by modulating the Walker circulation. This has resulted in a rapid warming of the Indian Ocean, and consequently a weakening of the Asian Monsoon.
A radionuclide (radioactive nuclide, radioisotope, radioactive isotope, or unstable isotope) is a nuclide that is unstable and known to undergo radioactive decay into a different nuclide, which may be another radionuclide (see decay chain) or be stable. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. For a collection of atoms of a single nuclide, their average decay rate can be measured, and its half-life (t1/2) calculated. Half-lives vary by 55 orders of magnitude and have no known limits. All chemical elements have radionuclides - even the lightest, hydrogen, has a well-known radionuclide, tritium (though helium, lithium, and boron have none with half-life over a second). Elements heavier than lead (Z > 82), and the elements technetium and promethium, have only radionuclides and do not exist in stable forms, though bismuth can be treated as stable with the half-life of its natural isotope being over a trillion times longer than the current age of the universe. Radiation emitted by radionuclides is almost always ionizing radiation and exposure above a certain level can cause damage to living organisms.
Sources: en.wikipedia.org
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.