A practical reference on freeze-thaw: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-06-13 and is reviewed periodically as new material appears.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
==== Partially competitive ==== The mechanism of partially competitive inhibition is similar to that of non-competitive, except that the EIS complex has catalytic activity, which may be lower or even higher (partially competitive activation) than that of the enzyme–substrate (ES) complex. This inhibition typically displays a lower Vmax, but an unaffected Km value.
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February 4: Abolition of slavery in French colonies (not applied in some later-acquired colonies; slavery reestablished in most colonies from 1802, except Saint-Domingue, independent in 1804). March 12: Possibility to annul religious vows made before age 18 for girls or 21 for boys. 1795
Sources: en.wikipedia.org
==== September ==== The Syrian Observatory for Human Rights reported that Firas Hamayel, a commander in the National Guard, was killed in an ambush in Suwayda. On 21 September, Ayoob Kara, former member of the Israeli Knesset, announced the independence of Suwayda, declaring "We proclaim September 21, 2025, as the historic day of Suwayda’s separation from Syria and from the terrorist government of Ahmed Al-Sharaa". On 26 September, the Syrian Druze militias established a local women's self-defense army as a response to the precarious security situation. More than 500 women are involved. Minors have been forcibly trained to use weapons. On 27 September, the Syrian transitional government bombed the city of Mecdel with a drone and also bombed the city of Kanaker.
having an acceptable treatment protocol in place that changes the outcome for patients diagnosed early with the disease an understanding of the condition's natural history an understanding about who will be treated as a patient a screening test that is reliable for both affected and unaffected patients and is acceptable to the public As diagnostic techniques have progressed, debates have arisen as to how screening programs should adapt. Tandem mass spectrometry has greatly expanded the potential number of diseases that can be detected, even without satisfying all of the other criteria used for making screening decisions. Duchenne muscular dystrophy is a disease that has been added to screening programs in several jurisdictions around the world, despite the lack of evidence as to whether early detection improves the clinical outcome for a patient.
== History and programs == GAVI was created in 2000 as a successor to the Children's Vaccine Initiative, which was launched in 1990. In August 2014, Gavi changed its name from "GAVI Alliance" and rebranded itself with a new logo deliberately reminiscent of UN organization logos, but using green as a mark of difference. As mentioned above, Gavi plans its operations in terms of five-year stretegies to make it easier to negotiate longer-term deals. Gavi 6.0 (2026–2030) was approved by the Gavi board in June 2024. One of the goals is to build country-led, sustainable vaccination programs.
== See also == List of actors with Academy Award nominations List of actors with more than one Academy Award nomination in the acting categories List of actors nominated for Academy Awards for non-English performances List of Golden Globe winners List of oldest and youngest Academy Award winners and nominees – Youngest nominees for Best Supporting Actor Species named after DiCaprio Grouvellinus leonardodicaprioi – Species of beetle Spintharus leonardodicaprioi – Species of spider
Sources: en.wikipedia.org
Vitamin B3, colloquially referred to as niacin, is a vitamin family that includes three forms, or vitamers: nicotinic acid (niacin), nicotinamide (niacinamide), and nicotinamide riboside. All three forms of vitamin B3 are converted within the body to nicotinamide adenine dinucleotide (NAD). NAD is required for human life and people are unable to make it within their bodies without either vitamin B3 or tryptophan. Nicotinamide riboside was identified as a form of vitamin B3 in 2004. Niacin (the nutrient) can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variety of whole and processed foods, with highest contents in fortified packaged foods, meat, poultry, red fish such as tuna and salmon, lesser amounts in nuts, legumes and seeds. Niacin as a dietary supplement is used to treat pellagra, a disease caused by niacin deficiency. Signs and symptoms of pellagra include skin and mouth lesions, anemia, headaches, and tiredness. Many countries mandate its addition to wheat flour or other food grains, thereby reducing the risk of pellagra. The amide nicotinamide is a component of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP+). Although nicotinic acid and nicotinamide are identical in their vitamin activity, nicotinamide does not have the same pharmacological, lipid-modifying effects or side effects as nicotinic acid, i.e., when nicotinic acid takes on the -amide group, it does not reduce cholesterol nor cause flushing.
Vegetarians, and vegetarian themes, have appeared in various TV shows, such as Buffy the Vampire Slayer, True Blood, The Simpsons, King of the Hill, and South Park. Mr. Spock of Star Trek has been called "television's first vegetarian." He and his fellow Vulcans do not eat meat due to a "philosophy of non-violence." He is identified as vegetarian following an episode where he was "transported back to pre-civilised times" and ate meat, and in Richard Marranca, in an issue of the Vegetarian Journal, said that for Spock, like Kwai Chang Caine in Kung Fu, "vegetarianism was something authentic and taken for granted; it was the right thing to do based on compassion and logic." In 1995, The Simpsons episode "Lisa the Vegetarian" aired. Before recording their lines for the episode, showrunner David Mirkin, who had recently stopped consuming meat, gave Linda and Paul McCartney "a container of his favorite turkey substitute," with both voicing characters in an episode which focused around vegetarianism. Critic Alan Siegel said that before the episode vegetarians had been portrayed as "rarely as anything but one-dimensional hippies" but that this episode was different as it was "told from the point of view of the person becoming a vegetarian." He said that the episode was one of the "first times on television that vegetarians saw an honest depiction of themselves" and of people's reaction to their dietary choices. The idea for the episode was originally proposed by David X.
A sausage roll is a savoury dish, popular in current and former Commonwealth nations, consisting of sausage meat wrapped in puff pastry. Although variations are known throughout Europe and in other regions, the sausage roll is most closely associated with British cuisine. The British bakery chain Greggs sells around 2.5 million sausage rolls per week, or around 140 million per year.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.