The short version of HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
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.
=== Origins === The first investigative radiochemical measurements began in the early days of nuclear fission. In 1944, the US Air Force made the first attempts to detect fissiogenic 133Xe in the atmosphere in order to indicate the production of plutonium through the irradiation of uranium and chemical reprocessing in an effort to gather intelligence on the status of the German nuclear program. However, no 133Xe was detected.
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=== Music === TikTok has been noted by many media outlets as having a major influence in the music industry. American artist Lil Nas X notably rose to fame after his song "Old Town Road" went viral on TikTok in 2019. He acknowledged the platform's influence in popularizing the song, saying "[TikTok] really boosted the song ... I credit them a lot". Doja Cat has also been noted as an artist who achieved mainstream popularity thanks to her success on TikTok. Insider noted in 2020 that "one of the most popular, pervasive dances of all time" from TikTok was set to Say So, which became her first no.1 hit on the Billboard Hot 100. Pitchfork also noted Doja Cat's "astonishing, unprecedented TikTok reign", saying that before her fame on TikTok, "many people didn't fully register Doja Cat as a star". When it was launched, TikTok allowed users to upload videos that ranged from 3 seconds to 1 minute. The short video length limit led to users making sped-up versions of songs to use in their videos. This allowed them to fit more of the song in their video. Some artists, including SZA and Steve Lacy, released official sped-up versions of their songs after unofficial sped-up remixes of their songs went viral on the platform. TikTok has also helped popularize older songs. Fleetwood Mac's song Dreams re-entered the Billboard Hot 100 over 40 years after its release after a video that featured the song went viral on the platform. Dan Whateley from Insider noted that songs could "rise up organically on the app even if they've been outside the mainstream for decades".
Upregulation An increase in the number or sensitivity of receptors on a neuron, often in response to reduced stimulation or drug exposure. A mechanism of plasticity. Utricle A structure within the vestibular system that detects linear acceleration and head position relative to gravity. Works in tandem with the saccule. Uveitis Inflammation of the uveal tract (including the iris, ciliary body, and choroid), which can cause visual disturbances and is sometimes associated with autoimmune neurological disorders.
Sources: en.wikipedia.org
In February 2022, Carrey reprised his role as Ernie "Chip" Douglas, from the 1996 movie The Cable Guy, in a commercial for Verizon, which aired during the Super Bowl. In April 2022, Carrey announced that he was considering retirement, saying: "I have enough. I've done enough. I am enough." He said he would return to acting if "angels bring some sort of script that's written in gold ink that says to me that it's going to be really important for people to see". In February 2024, it was announced that Carrey would reprise his role as Dr. Ivo Robotnik in Sonic the Hedgehog 3. A copy of the script for Sonic the Hedgehog 3 was delivered to Carrey written in 24-carat ink in reference to his previous comments. Carrey also plays Ivo Robotnik's grandfather, Gerald Robotnik. Carrey reportedly told an Associated Press reporter that he agreed to return to the Sonic universe because "I need the money, frankly." He later clarified in interviews in December 2024 that he planned to "power rest" rather than retire, while also stating that he was open to continuing his role in the Sonic film series. In March 2026, Carrey was announced to return as Dr. Ivo Robotnik in Sonic the Hedgehog 4 (2027). In August 2026, Carrey was announced to star in the upcoming live-action film The Jetsons, but his role is yet to be confirmed.
== Deaths == 3 January – Derek Draper, 56, lobbyist and political adviser. 15 January – James Masih Shera, 77, Pakistani-born British politician and educationist. 17 January – Sir Tony Lloyd, 73, British politician, MP (1983–2012, since 2017) and mayor of Greater Manchester (2015–2017), leukemia. 19 January – Sir Graham Bright, 81, British politician, MP (1979–1997) and Cambridgeshire police and crime commissioner (2012–2016). 20 January – John Tomlinson, Baron Tomlinson, 84, British politician, MP (1974–1979) and MEP (1984–1999). 6 February – Shreela Flather, Baroness Flather, 89, British-Indian politician, Life peer (since 1990). 23 February – Ronnie Campbell, 80, British politician, MP (1987–2019). 25 February – Patrick Cormack, Baron Cormack, 84, British politician, MP (1970–2010) and member of the House of Lords (since 2010). (death announced on this date) 26 February – Jacob Rothschild, 4th Baron Rothschild, 87, British investment banker and peer, member of the House of Lords (1991–1999). 29 February – Ruth Henig, Baroness Henig, 80, historian and politician, member of the House of Lords (since 2004), Deputy Speaker of the House of Lords (since 2018). 8 March – Tommy McAvoy, Baron McAvoy, 80, British politician, MP (1987–2010) and member of the House of Lords (since 2010). (death announced on this date) 6 April – Doug Hoyle, Baron Hoyle, 98, British politician, MP (1974–1979, 1981–1983) and member of the House of Lords (1997–2023). 10 April – Richard Rosser, Baron Rosser, 79, British trade unionist and politician, member of the House of Lords (since 2004).
=== Typical interpretation of results === Previous treatment guidelines recommended that anyone with a viral load greater than 100,000 copies/mL of blood should begin treatment. It is now standard of care in the United States to begin anti-retroviral treatment upon discovery of HIV positive status. HIV is a retrovirus, an RNA virus that enters a host cell and uses the host DNA replication machinery and the enzyme reverse transcriptase to produce DNA from the viral RNA genome. HIV also produces an integrase enzyme which is used to integrate the newly produced viral DNA into the host's DNA. The virus is then replicated every time the host cell's DNA replicates. Due to the nature of the virus the drugs used to treat HIV are called antiretroviral medicines, and the course of treatment is called antiretroviral therapy (ART). These potent medicines cannot cure an individual; they can however manage the virus and slow the progression of the HIV infection. Strict compliance with the prescribed ART regimen is vital to controlling the disease. Highly active antiretroviral therapy (HAART) is the current recommended treatment for HIV. HAART entails taking a combination (regimen) of three or more ART medications from at least two different classes of drugs. There are six classes of ART medications:
Sources: en.wikipedia.org
Furazolidone is a nitrofuran antibacterial agent and monoamine oxidase inhibitor (MAOI). It is marketed by Roberts Laboratories under the brand name Furoxone and by GlaxoSmithKline as Dependal-M. Furazolidone has been used in human and veterinary medicine. It has a broad spectrum of activity, being active against: Gram-positive bacteria Clostridium perfringens Corynebacterium pyogenes Streptococci Staphylococci Gram-negative bacteria Escherichia coli Salmonella dublin Salmonella typhimurium Shigella Protozoa Giardia lamblia Eimeria species Histomonas meleagridis
=== Rutherfordium and dubnium === During the height of the Cold War, teams from the Soviet Union and the United States independently created rutherfordium and dubnium. The naming and credit for synthesis of these elements remained unresolved for many years, but eventually, shared credit was recognized by IUPAC/IUPAP in 1992. In 1997, IUPAC decided to give dubnium its current name, honoring the city of Dubna where the Russian team worked since American-chosen names had already been used for many existing synthetic elements, while the name rutherfordium (chosen by the American team) was accepted for element 104.
The report found that AI has significant negative impacts on land, water, and climate, as it uses large amounts of electricity, requires mining of minerals, and generates large amounts of electronic waste. In 2025, data centres consumed more electricity than Saudi Arabia, and ChatGPT alone consumed an amount of water equivalent to the needs of 500,000 people in Sub-Saharan Africa. The negative impacts are not distributed equally across the planet but are concentrated in some places. Data centres are often built in places already suffering from water deficit. For example, AI deployment has already led to an increase in water scarcity in Mexico and Uruguay. It created problems with energy supply in Ireland, which forbade construction of new data centres near Dublin until 2028. Measures can involve tradeoffs, for example, transitioning from coal to bioenergy reduces carbon footprint but increases the impact on land and water. Energy efficiency might not reduce environmental impact, because as AI becomes more efficient, it also becomes cheaper and more widely used.
When Inside Soap's Sarah Ellis asked Weir why Mac is so attracted to Tane when Ari is "the sensible brother, who would undoubtedly give Mackenzie a secure future and everything she needs", Weir replied that it was a case of what her character is normally attracted to versus what she actually needs. When a jealous Mac fights with Tane's love interest Amber Simmons (Maddy Jevic), she knows that it will likely get back to Ari, so she tells him how she feels about his brother. Weir described her character as "very moral" and stressed that she would never cheat on Ari, but when he started to pick up on the tension between her and Tane, she knows that she cannot lie to him. Weir also said that the whole incident makes Mac realise that she does have serious feelings for Ari. Mac eventually tells Ari that she wants more than a casual relationship and if he cannot give her more commitment, then she will walk away. Ari realises that he has not given his relationship with Mac a fair chance, so he takes her out on a fishing date. Ari opens up to Mac and tells her that he has "lost his way" when it comes to romance since his time in prison, but he hopes the date will teach her more about him. Kipa-Williams said "It was a life that landed him in prison for something he regrets dearly. He doesn't want to make any mistakes again." Mac admits to Ari that she used to go fishing as a child, making their trip "the perfect date" and the pair start afresh as a proper couple. In an interview with Daniel Kilkelly of Digital Spy, Weir believed Ari was "the best match" for Mac.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.