certificate of analysis comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-10-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For lyophilized powder, long term |
| Common analytical method | Reverse-phase HPLC | Usually paired with mass spectrometry |
| Typical reported purity | At or above 95 percent by area | Research-grade material |
| Aqueous solubility | High | Solutions used in laboratory assays |
| Moisture sensitivity | Hydrolyzes in solution | Aseptic handling reduces degradation |
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
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.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
=== Other benefits === Against the background of the overwhelmingly negative effects of smoking on health, some observational studies have suggested that smoking might have specific beneficial effects, including in the field of cardiovascular disease. Interest in this epidemiological phenomenon has also been aroused by COVID-19. Systematic review of reports that suggested smokers respond better to treatment for ischemic stroke provided no support for such claims. Claims of surprising benefits of smoking, based on observational data, have also been made for Parkinson's disease, as well as a variety of other conditions, including basal-cell carcinoma, melanoma, acute mountain sickness, pemphigus, celiac disease, and ulcerative colitis, among others. Tobacco smoke has many bioactive substances, including nicotine, that are capable of exerting a variety of systemic effects. Surprising correlations may also stem from non-biological factors such as residual confounding (that is to say, the methodological difficulties in completely adjusting for every confounding factor that can affect outcomes in observational studies). For example, in his book Probably Overthinking It, the author Allen B. Downey dissects how a misinterpretation of data on low birth weight of babies born to smoking mothers delayed public-health recommendations against smoking during pregnancy by almost a decade.
A transaminase converts the oxaloacetate to aspartate for transport back across the membrane and into the intermembrane space. In oxidative phosphorylation, the passage of electrons from NADH and FADH2 through the electron transport chain releases the energy to pump protons out of the mitochondrial matrix and into the intermembrane space. This pumping generates a proton motive force that is the net effect of a pH gradient and an electric potential gradient across the inner mitochondrial membrane. Flow of protons down this potential gradient – that is, from the intermembrane space to the matrix – yields ATP by ATP synthase. Three ATP are produced per turn. Although oxygen consumption appears fundamental for the maintenance of the proton motive force, in the event of oxygen shortage (hypoxia), intracellular acidosis (mediated by enhanced glycolytic rates and ATP hydrolysis), contributes to mitochondrial membrane potential and directly drives ATP synthesis. Most of the ATP synthesized in the mitochondria will be used for cellular processes in the cytosol; thus it must be exported from its site of synthesis in the mitochondrial matrix. ATP outward movement is favored by the inner mitochondrial membrane's electrochemical potential because the cytosol has a relatively positive charge compared to the relatively negative matrix. For every ATP transported out, it costs 1 H+. Producing one ATP costs about 3 H+. Therefore, making and exporting one ATP requires 4H+.
=== GLC (1981–1985) === The equivalent American Mazda GLC (Great Little Car) appeared in the 1981 model year, although the rear-wheel drive wagon also continued to be offered. It was only offered with a single engine – the twin-barrel 1.5-litre with 68 hp (51 kW)—and lasted through 1985, after which it was replaced by the next-generation Mazda 323. With this, the GLC nameplate was retired. The BD was the only front-wheel drive Mazda vehicle using the GLC name. Originally it was offered with three- or five-door bodywork, in standard, Custom, Custom L, or Sport equipment levels. The five-door only came as a Custom and was sold only in Hawaii and Puerto Rico. All cars received exposed rectangular sealed-beam units. The later four-door saloon, introduced for 1983, was available in Custom, Custom L, and Sport models. The Sport received blacked out trim, a steering wheel borrowed from the RX-7, full instrumentation, and a special rear interior which closely integrates the side trim with the rear seat design – an early iteration of a design philosophy taken to its extreme with the 1988 Persona and the 1990 Eunos Cosmo. Unlike the sporting 323s in other markets, the Sport only received special hubcaps, rather than alloy wheels. For 1982, the Sport was made to live up to its name a little bit more, with the installation of a front anti-roll bar and cast aluminum wheels. The five-door GLC gained a fully carpeted trunk for 1982.
== O == Severo Ochoa (1905–1993). Spanish and American biochemist at New York University, major contributor to elucidating the genetic code. Nobel Prize in Physiology or Medicine (1959). Member Natl. Acad. Sci. USA. Alexander George Ogston FRS (1911–1996). British biochemist at Oxford University, known for the three-point attachment explanation of how an achiral substance can have a chiral product in the tricarboxylate cycle. Reiji Okazaki (1930–1975). Japanese molecular biologist at Nagoya University, known for discovering Okazaki fragments, an essential step for understanding DNA replication. Tsuneko Okazaki (b. 1933). Japanese molecular biologist at Nagoya University, known for discovering Okazaki fragments, an essential step for understanding DNA replication. L'Oréal-UNESCO Award for Women in Science. Joan Oró (1923–2004). Spanish biochemist at the University of Houston. Prominent for studies of the origin of life. Muriel Wheldale Onslow (1880–1932). British biochemist at Cambridge University, pioneer in biochemical genetics who worked on petal colour in flowers. Alexander Oparin, (1894–1980). Soviet biochemist at Moscow State University, known for his theory on the origin of life in coacervates. Full Member of the USSR Academy of Sciences. Mary Osborn (b. 1940). English cell biologist at the University of Göttingen known for developing techniques for determining protein molecular masses. Mary Jane Osborn (1927–2019). American biochemist at the University of Connecticut, who worked on lipopolysaccharides, and discovered the mechanism of action of methotrexate.
=== Foe === A foe is a unit of energy equal to 1044 joules (≈9.478×1040 BTU) that was invented by physicist Gerry Brown of Stony Brook University. To measure the staggeringly immense amount of energy produced by a supernova, specialists occasionally use the "foe", an acronym derived from the phrase [ten to the power of] fifty-one ergs, or 1051 ergs. This unit of measure is convenient because a supernova typically releases about one foe of observable energy in a very short period of time (which can be measured in seconds).
Sources: en.wikipedia.org
==== Potential path: sludge to food ==== PFOA and PFOS were detected in "very high" (low parts per million) levels in agricultural fields for grazing beef cattle and crops around Decatur, Alabama. The approximately 5000 acres of land were fertilized with "treated municipal sewage sludge, or biosolids". PFOA was also detected in fodder grass grown in these soils and the blood of the cattle feeding on this grass. The water treatment plant received process wastewater from a nearby perfluorochemical manufacturing plant. 3M says they managed their own wastes, but Daikin America "discharged process wastewater to the municipal waste treatment plant". If traced to meat, it would be the first time perfluorochemicals were traced from sludge to food. However, the USDA reported—with a detection limits of 20 parts per billion—non-detectable levels for both PFOA and PFOS in cattle muscle tissue.
The substances were more effective than placebo in the two studies included but the authors state that "the evidence was of insufficient quality to be conclusive" and note that "because alternative antidepressants exist which have been proven to be effective and safe, the clinical usefulness of 5-HTP and tryptophan is limited at present". The use of tryptophan as an adjunctive therapy in addition to standard treatment for mood and anxiety disorders is not supported by the scientific evidence.
He arranged for the bosses of the leading banks and building societies to tour the area in a coach (they were reluctant until Heseltine's PPS Tim Sainsbury persuaded Robin Leigh-Pemberton of NatWest to come), and asked them to each second a bright young manager to the DOE for a year. Heseltine circulated a 21-page minute to Cabinet on his return, entitled It Took a Riot. He proposed a regional office and a review of the status of the Metropolitan Counties, as well as greater government emphasis on Merseyside in future. He had prepared the ground with a small dinner for Whitehall mandarins including Robert Armstrong (Cabinet Secretary) and Ian Bancroft (Head of the Civil Service). However, Thatcher was not impressed, although she agreed to his appointment as Minister for Merseyside for twelve months. Neither was Keith Joseph (Secretary of State for Industry) nor Howe (Chancellor of the Exchequer), who favoured enterprise zones where businesses would be given favourable tax treatment. Shortly after his appointment as Minister for Merseyside, Heseltine gave his annual party conference speech, in which he condemned talk of repatriation and called for more public spending on inner cities. Although he felt he had taken a risk – the speech was in marked contrast to Norman Tebbit's "On Your Bike" speech a few hours later – he received his usual standing ovation and later recorded that it was the one of his speeches of which he was most proud.
== Production == The manufacturing process of pea protein concentrates and isolates consists of protein extraction, purification, and drying. The industrial production of pea protein begins with the steps of cleaning and splitting the pea crop and then processing them further. The cleaning process: Cleaning uses equipment such as indent cleaners, which are used to remove impurities. This process ensures that any allergens, such as wheat, barley and other seeds are removed, as these products contain gluten. If not removed, it would affect its classification as a gluten-free product. The splitting process: Following cleaning, the pea is split and "dehulled" using a dehuller. The dehullers are a device that splits the pea seed and extracts the part of the whole seed which is the hull. Further processing: Following the splitting process, the split peas are further processed either into starch, protein, and flour fractions. Pea protein can be produced using two methods:
Strassman argues that the more positive of the "external entities" encountered in DMT experiences should be understood as analogous to certain forms of angels: The medieval Jewish philosophers whom I rely upon for understanding the Hebrew Bible text and its concept of prophecy portray angels as God's intermediaries. That is, they perform a certain function for God. Within the context of my DMT research, I believe that the beings that volunteers see could be conceived of as angelic – that is, previously invisible, incorporeal spiritual forces that are engarbed or enclothed in a particular form – determined by the psychological and spiritual development of the volunteers – bringing a particular message or experience to that volunteer. Strassman's experimental participants also note that some other entities can subjectively resemble creatures more like insects and aliens. As a result, Strassman writes these experiences among his experimental participants "also left me feeling confused and concerned about where the spirit molecule was leading us. It was at this point that I began to wonder if I was getting in over my head with this research." Hallucinations of strange creatures had been reported by Stephen Szára in a 1958 study in psychotic patients, in which he described how one of his subjects under the influence of DMT had experienced "strange creatures, dwarves or something" at the beginning of a DMT trip.
Sources: en.wikipedia.org
29 September Last Neanderthal?, the unanswered question of the Neanderthal extinction, with Sir Paul Mellars of the University of Cambridge; Pat Shipman of Penn State University; science writer James Shreeve; anthropologist Randall White of New York University; the first complete skeleton was found in 1908 and given to Marcellin Boule; Milford H.
=== Biomedical applications === Quantitative proteomics has distinct applications in the medical field. Especially in the fields of drug and biomarker discovery. LC-MS/MS techniques have started to over take more traditional methods like the western blot and ELISA due to the cumbersome nature of labeling different and separating proteins using these methods and the more global analysis of protein quantification. Mass spectrometry methods are more sensitive to difference in protein structure like post-translational modification and thus can quantify differing modifications to proteins. Quantitative proteomics can circumvent these issues, only needing sequence information to be performed. It can be applied on a global proteome level, or on specifically isolating binding partners in pull-down or affinity purification experiments. Disadvantages, however, in sensitivity and analysis time must be kept in consideration.
models the transition rate from the compartment of susceptible individuals to the compartment of infectious individuals, so that it is called the force of infection. However, for large classes of communicable diseases it is more realistic to consider a force of infection that does not depend on the absolute number of infectious subjects, but on their fraction (with respect to the total constant population
4 September: Immigration Minister Erica Stanford confirms that the Government will introduce legislation to make it easier to deport criminals holding permanent residency visas. Carter Holt Harvey confirms plans to close down its Eves Valley sawmill in Tasman District by late November 2025, affecting over 140 jobs. Mayor of Tasman Tim King and Mayor of Nelson Nick Smith had appealed to the forestry company to delay the closure in order to clear fallen trees and vegetation caused by the Winter 2025 New Zealand floods. The New Zealand Police drop sexual misconduct criminal charges against former Deputy Police Commissioner Jevon McSkimming after an independent barrister deemed the evidence as insufficient to meeting the prosecution threshold. He still faces charges of possession of objectionable material. 5 September: Green Party MP Benjamin Doyle announces they would be resigning from Parliament effective 3 October, citing safety concerns. The Sealord Group proposes closing its coated fish factory in Nelson, New Zealand, potentially affecting 79 jobs. The Association of Salaried Medical Specialists rejects Health Minister Simeon Brown's request that the union enter into binding arbitration with Te Whatu Ora (Health New Zealand). Māori Queen Nga wai hono i te po announces two economic initiatives: namely a summit to develop economic opportunities for Māori and a seed investment fund supported by Māori entities. Thunderstorms and strong winds disrupt 28 flights at Wellington International Airport and lead to the closure of New Zealand State Highway 2.
Taking up his duties in 1920, Robertson was immediately identifying himself as "Professor of Physiology and Biochemistry"; thus, in Robertson, the University of Adelaide had the first-ever Australian Chair in Biochemistry — almost two decades before the 1938 appointments of William John Young at the University of Melbourne and Henry Priestley at the University of Sydney.
Sources: en.wikipedia.org
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.
Lyophilized powder is usually kept frozen and protected from moisture. Solutions are less stable and are often used promptly or divided into aliquots to avoid repeated freeze-thaw cycles. Exact shelf-life values depend on purity and handling.
No. A purity figure derived from chromatographic area does not prove the amino acid sequence. Identity requires an orthogonal method such as mass spectrometry or sequencing. Truncated or isomerized peptides can co-elute with the target compound.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.