If you have been reading about mass spectrometry and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-27. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
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.
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.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
=== Future developments === Several medications designed to address the root cause are under development, including gene therapy and antisense drugs. Other medications used include corticosteroids to slow muscle degeneration. Physical therapy, orthopedic braces, and corrective surgery may help with some symptoms while assisted ventilation may be required in those with weakness of breathing muscles. Outcomes depend on the specific type of disorder. In February 2024, the results of a 48-week trial with Vamorolone in patients with Duchenne muscular dystrophy (The VISION-DMD study) were published. Patients showed improvements in motor outcomes seen with 6 mg/kg/d of Vamorolone at 24 weeks of treatment and were maintained for 48 weeks of treatment. As well, bone morbidities of prednisone (stunting of growth and declines in serum bone biomarkers) were reversed when treatment transitioned to Vamorolone.
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=== Radio wave absorption === Stacked graphene layers on a quartz substrate increased the absorption of millimeter (radio) waves by 90 per cent over 125–165 GHz bandwidth, extensible to microwave and low-terahertz frequencies, while remaining transparent to visible light. For example, graphene could be used as a coating for buildings or windows to block radio waves. Absorption is a result of mutually coupled Fabry–Perot resonators represented by each graphene-quartz substrate. A repeated transfer-and-etch process was used to control surface resistivity.
9 February – Donald Cameron, a Conservative list MSP for the Highlands and Islands, announces he is standing down from the Scottish Parliament to take up a seat in the House of Lords and a junior ministerial post in the Scottish Office. 10 February – Police Scotland are investigating 22 deaths that occurred at the Fullarton Care Home in Irvine, North Ayrshire during the COVID-19 pandemic. The home was one of the worst affected during the early days of the pandemic. 11 February – Canadian woman Claire Leveque, aged 24, dies following a disturbance in Sandness, Shetland. Aren Pearson is subsequently charged with her murder. 12 February – Actor and writer Simon Fanshawe is named the new Rector of the University of Edinburgh, succeeding Debora Kayembe. A man is arrested and charged over several acts of vandalism in Glasgow, including graffiti relating to the Gaza conflict daubed on the city's cenotaph. 13 February – Former NHS worker Tracy Menhinick, who gave a young boy "industrial amounts" of the laxative lactulose, is found guilty of poisoning the child following a 19-day trial at the High Court in Aberdeen. 14 February – Jordan Mitchell, who spoke about his desire to commit mass murder in Falkirk during a hospital visit, and who said he had killed animals, is given an Order for Lifelong Restriction by the Court of Criminal Appeal. 15 February – Glasgow City Council and North Lanarkshire Council vote to freeze council tax for the 2024–25 financial year.
==== Environmental remediation ==== Nanoremediation is the use of nanoparticles for environmental remediation. Nanoremediation has been most widely used for groundwater treatment, with additional extensive research in wastewater treatment. Nanoremediation has also been tested for soil and sediment cleanup. Even more preliminary research is exploring the use of nanoparticles to remove toxic materials from gases. Some nanoremediation methods, particularly the use of nano zerovalent iron for groundwater cleanup, have been deployed at full-scale cleanup sites. Nanoremediation is an emerging industry; by 2009, nanoremediation technologies had been documented in at least 44 cleanup sites around the world, predominantly in the United States. During nanoremediation, a nanoparticle agent must be brought into contact with the target contaminant under conditions that allow a detoxifying or immobilizing reaction. This process typically involves a pump-and-treat process or in situ application. Other methods remain in research phases. Scientists have been researching the capabilities of buckminsterfullerene in controlling pollution, as it may be able to control certain chemical reactions. Buckminsterfullerene has been demonstrated as having the ability of inducing the protection of reactive oxygen species and causing lipid peroxidation. This material may allow for hydrogen fuel to be more accessible to consumers.
Sources: en.wikipedia.org
The female lays three to seven eggs, which both sexes help to incubate. Its breeding range extends from central and western Alaska across northern Canada to Nova Scotia, and south throughout North America, into central Mexico and the Caribbean. It is a local breeder in Central America and is widely distributed throughout South America. Most birds breeding in Canada and the northern United States migrate south in the winter. It is an occasional vagrant to Western Europe. The American kestrel is often used in falconry, especially by beginners. Though not as strong a flyer as many other, larger falcons, proper training and weight control by the falconer can allow captive American kestrels to become effective hunters of birds in the size range of sparrows and starlings, with occasional success against birds up to approximately twice their own weight.
The lone star tick (Amblyomma americanum), which is found throughout the Southeastern United States as far west as Texas, is unlikely to transmit Lyme disease spirochetes, though it may be implicated in a related syndrome called southern tick-associated rash illness, which resembles a mild form of Lyme disease.
=== Contamination === Any addition of carbon to a sample of a different age will cause the measured date to be inaccurate. Contamination with modern carbon causes a sample to appear to be younger than it really is: the effect is greater for older samples. If a sample that is 17,000 years old is contaminated so that 1% of the sample is modern carbon, it will appear to be 600 years younger; for a sample that is 34,000 years old, the same amount of contamination would cause an error of 4,000 years. Contamination with old carbon, with no remaining 14C, causes an error in the other direction independent of age – a sample contaminated with 1% old carbon will appear to be about 80 years older than it truly is, regardless of the date of the sample.
== Side effects == The most common side effect in all insulin analogues is low blood sugar, while in more serious cases, side effects may include low blood potassium. Insulin allergies are also a concern, although they are not prevalent, affecting only about 2% of people in some form. Insulin analogues are generally considered safe during pregnancy, and many are used in the treatment of gestational diabetes.
==== On Unnatural Amino Acids ==== Pd-mediated Sonogashira, Heck, and Suzuki-Miyaura cross-coupling reactions have been applied widely to modify peptides and proteins, where diverse Pd reagents have been developed for the application in aqueous solutions. Those reactions require the protein or peptide substrate bearing unnatural functional groups such as alkyne, aryl halides, and aryl boronic acids, which can be achieved through genetic code expansion or post-translational modifications.
Sources: en.wikipedia.org
== Semiconductor == The total current flow in the semiconductor consists of drift current and diffusion current of both the electrons in the conduction band and holes in the valence band. General form for electrons in one-dimension:
Promoting absorption of dietary calcium from the gastrointestinal tract. Increasing renal tubular reabsorption of calcium, thus reducing the loss of calcium in the urine. Stimulating release of calcium from bone. For this it acts on the specific type of bone cells referred to as osteoblasts, causing them to release RANKL, which in turn activates osteoclasts. Calcitriol acts in concert with parathyroid hormone (PTH) in all three of these roles. For instance, PTH also indirectly stimulates osteoclasts. However, the main effect of PTH is to increase the rate at which the kidneys excrete inorganic phosphate (Pi), the counterion of Ca2+. The resulting decrease in serum phosphate causes hydroxyapatite (Ca5(PO4)3OH) to dissolve out of bone, thus increasing serum calcium. PTH also stimulates the production of calcitriol (see below). Many of the effects of calcitriol are mediated by its interaction with the calcitriol receptor, also called the vitamin D receptor or VDR. For instance, the unbound inactive form of the calcitriol receptor in intestinal epithelial cells resides in the cytoplasm. When calcitriol binds to the receptor, the ligand-receptor complex translocates to the cell nucleus, where it acts as a transcription factor promoting the expression of a gene encoding a calcium binding protein. The levels of the calcium binding protein increase enabling the cells to actively transport more calcium (Ca2+) from the intestine across the intestinal mucosa into the blood. Alternative, non-genomic pathways may be mediated through either PDIA3 or VDR.
Prescriber education guidelines as well as patient education, prescription drug monitoring programs and regulation of pain clinics are regulatory tactics which have been used to curtail opioid use and misuse.
Sporulation is stimulated by amino acids (except L-valine) when grown in light, while in darkness only L-tryptophan and L-methionine effect stimulation of growth. The columellae are globose, subglobose, or oval in shape. The wall is usually smooth and the colour is pale brown. The average diameter growth ranges from 30-110 μm. Sporangiospores are elliptical, globose, or polygonal, they are striated and grow 5-8 μm in length. Dormant and germinated sporangiospores show deep furrows and prominent ridges with a pattern that makes it distinguishable from that of R. stolonifer. The germination of sporangiospores can be induced by the combined action of L-proline and phosphate ions. L-ornithine, L-arginine, D-glucose and D-mannose are also effective. Optimal germination occurs on media containing D-glucose and mineral salts.R. oryzae has abundant, root-shaped rhizoids. Zygospores are produced by diploid cells when sexual reproduction occurs under nutrient poor conditions. They have colors that range from red to brown, they are spherical or laterally flattened, and ranges from 60-140μm in size. In high nutrient levels, R. oryzae reproduces asexually, producing azygospores. The stolons found in R. oryzae are smooth or slightly rough, almost colorless or pale brown, 5-18 μm in diameter. The chlamydospores are abundant, globose ranging in 10-24 μm in diameter, elliptical, and cylindrical. Colonies of R. oryzae are white initially, becoming brownish with age and can grow to about 1 cm thick.
== Public listing, financials and governance == TCI is listed on Taiwan's OTC market (stock code 8436). Regulatory and investor pages report the company's registration details, public offering timeline (public offering 25 August 2011; OTC listing 12 September 2013), paid-in capital and disclosure contacts. Quarterly and annual reports are published on the company's investor relations pages.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.