Research chemical 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.
Updated 2025-09-13. Numbers and descriptions here follow the published literature rather than marketing material.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
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.
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.
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.
In this study, phospholipid membrane is comparable to the model membrane which consists of POPC, ethanol, water and in some cases the addition of monovalent ions (Na+, K+, and Cl−) that are transported throughout the membrane in the presence of ethanol. The concentration of ethanol varies ranging from 2.5 to 30 mol% in an aqueous solution but there is no addition of any sterol compound. The atomic-scale molecular dynamics simulations are used to monitor the changes in the phospholipid membrane. All the simulations are carried out using GROMACS simulation suite software along with other methods that are essential to perform the simulations. The temperature and pressure are controlled at 310K and 1bar. The simulations are measured at various time frames which include ficoseconds (fs), picoseconds (ps), and nanoseconds (ns). A typical simulation is composed of approximately 128 POPC lipids and 8000 solvent molecules which include water and ethanol. In each simulation ethanol molecules, water molecules, head group regions, acyl chains, and the monovalent ions are all color-coded which aids in interpreting the results of the simulations. The concentrations of ethanol are 2.5, 5.0, 15.0 and 30 mol%. The amount of ethanol molecules depend on the concentration of ethanol present in the phospholipid membrane. Force field parameters are measured for the POPC lipids and monovalent ions (Na+, K+, and Cl−), which are very important.
==== 2012 Jalisco massacres ==== The dismembered remains of 18 bodies were found inside a Toyota Sienna and Ford EcoSport near the U.S. retiree communities in Chapala, Jalisco, just south of the city of Guadalajara. Eighteen heads were found along the dismembered bodies; some had been frozen, others were covered in lime, and the rest were found in an advanced state of decomposition. An anonymous call alerted the police to the abandoned vehicles, which were found by the side of a highway early in the morning on 9 May 2012. They were consequently towed to government offices to unload the bodies. The authorities confirmed that a message was left behind by the killers, presumably from Los Zetas and the Milenio Cartel. The attorney general of the state of Jalisco, Tomás Coronado Olmos, stated that this massacre was a revenge attack for the 23 killed in the 2012 Nuevo Laredo massacres. In addition, 25 people were rescued after being kidnapped in Tala, Jalisco on 8 May 2012; the killers had plans to kill and "throw" them for public display. Another 10 people managed to escape their capture by members of Los Zetas that same day, and alerted the local media of the situation. Upon the arrest of the four alleged killers, one of the cartel members confessed that they had plans to "repeat" what had happened in the 2011 Guadalajara massacre, where 26 bodies were dumped in a major avenue for public display. According to Proceso magazine, Los Zetas were planning to kill 50 people on 9 May 2012, a day before Mother's Day.
=== Grafting techniques === Grafting copolymers to a surface can be envisioned as fixing polymeric chains to a structurally different polymer substrate with the intention of changing surface functionality while preserving bulk mechanical properties. The nature and degree of surface functionalization is determined by both the choice of copolymer and the type and extent of grafting.
Sources: en.wikipedia.org
Rather than having players go through convoluted interface menus to modify their weapons, upgrade their plasmids, or buy items, these functions were split into vending machines scattered around the game world. Early in level development, the levels were roughly blocked out, but no one was happy with the art department's attempts to decorate them. A critical junction was a short experiment performed by level designer Jean Paul LeBreton and artist Hoagy de la Plante, setting themselves aside to co-develop a level that became part of the "Tea Garden" area in the released game, which Levine used as a prime example of a "great BioShock space", emphasizing the need for departments to work together. BioShock uses a heavily modified Unreal Engine 2.5 with some of the advanced technologies from Unreal Engine 3. Irrational had previous experience with modifying and expanding on the Unreal Engine in SWAT 4, and continued this advancement of the engine within BioShock. Given the game's setting, one significant improvement was made in the water systems, hiring a programmer and artist to focus on the water effects. Finley recalled that the team's deep familiarity with Unreal Engine was a blessing and curse, as it made prototyping the game very quick, but they were also more willing to accept fast-to-implement but inefficient solutions that ultimately cost more development time. BioShock also uses the Havok Physics engine that allows for the integration of ragdoll physics, and allows for more lifelike movement by elements of the environment.
=== Occupational therapy === Occupational therapy—often abbreviated OT—is the "use of productive or creative activity in the treatment or rehabilitation of physically, cognitively, or emotionally disabled people." Most commonly, occupational therapists work with people with disabilities to enable them to maximize their skills and abilities. Occupational therapy practitioners are skilled professionals whose education includes the study of human growth and development with specific emphasis on the physical, emotional, psychological, sociocultural, cognitive and environmental components of illness and injury. They commonly work alongside clinical psychologists in settings such as inpatient and outpatient mental health, pain management clinics, eating disorder clinics, and child development services. OT's use support groups, individual counseling sessions, and activity-based approaches to address psychiatric symptoms and maximize functioning in life activities.
== Employment == Biochemists are typically employed in the life sciences, where they work in the pharmaceutical or biotechnology industry in a research role. They are also employed in academic institutes, where in addition to pursuing their research, they may also be involved with teaching undergraduates, training graduate students, and collaborating with post-doctoral fellows. Because of a biochemists' background in both biology and chemistry, they may also be employed in the medical, industrial, governmental, and environmental fields. Slightly more than half of the biological scientists are employed by the Federal State and local governments. The field of medicine includes nutrition, genetics, biophysics, and pharmacology; industry includes beverage and food technology, toxicology, and vaccine production; while the governmental and environmental fields includes forensic science, wildlife management, marine biology, and viticulture. The average income of a biochemist was $82,150 in 2017. The range of the salaries begin around 44,640 to 153,810, reported in 2017. The United States Federal Government in 2005 reported the average salaries in different fields associated with biochemistry and being a biochemist. General biological scientists in nonsupervisory, supervisory, and managerial positions earned an average salary of $69,908; microbiologists, $80,798; ecologists, $72,021; physiologists, $93,208; geneticists, $85,170; zoologists, $101,601; and botanists, $62,207.
The differences between laudanum and paregoric are important and should be kept in mind when administering either of these drugs. Care and caution should always be taken in administering doses of tincture of opium, such as the use of a dosage syringe or other suitable measurement device, and by pharmacists in preparing paregoric from laudanum, and to note that the dosages noted here refer to apothecaries weight and fluid measure. In particular, "the difference between a minim and a drop should be borne in mind when figuring doses. A minim is always a sixtieth part of a fluid drachm regardless of the character of the substance, while a drop varies from a forty-fifth to a two-hundred-and-fiftieth part, according to the surface tension of the fluid." Laudanum and paregoric each have 50.9 drops per gram; 50.0 drops per cc; 185.0 drops per fluid drachm; and 3.10 drops per minim." The importance of these distinctions is evident in view of the dangers of erroneously relying upon more general descriptions of apothecaries' fluid measures, which typically list 60 minims per fluid dram, and 8 fluid drams per fluid ounce (480 minims).
Sources: en.wikipedia.org
Singapore has a generally efficient healthcare system, having achieved high quality of care while also keeping expenditures low. The World Health Organisation ranks Singapore's healthcare system as 6th overall in the world in its World Health Report. Singapore has had the lowest infant mortality rates in the world for the past two decades. In 2019, Singaporeans had the longest life expectancy of any country at 84.8 years. Women can expect to live an average of 87.6 years with 75.8 years in good health. The averages are lower for men. Singapore is ranked 1st on the Global Food Security Index. As of December 2011 and January 2013, 8,800 foreigners and 5,400 Singaporeans were respectively diagnosed with HIV, but there are fewer than 10 annual deaths from HIV per 100,000 people. Adult obesity is below 10%. There is a high level of immunisation. In 2013, the Economist Intelligence Unit ranked Singapore as having the best quality of life in Asia and sixth overall in the world. The government's healthcare system is based upon the "3M" framework. This has three components: Medifund, which provides a safety net for those not able to otherwise afford healthcare; Medisave, a compulsory national medical savings account system covering about 85% of the population; and Medishield, a government-funded health insurance programme. Public hospitals in Singapore have considerable autonomy in their management decisions, and notionally compete for patients, but remain in government ownership. A subsidy scheme exists for those on low income.
=== Side-effects === Although patients at high risk of bleeding were excluded from the phase III clinical study (PROWESS), 25% of patients treated with drotrecogin and 18% of those receiving placebo experienced at least one bleeding event (principally ecchymoses or GI bleeding) during the 28-day study period. During treatment, serious bleeding events (e.g., intracranial hemorrhage, any life-threatening bleeding event, any bleeding event requiring administration of at least 3 units of packed red blood cells daily for 2 consecutive days) occurred in 2.4% of patients treated with drotrecogin and in 1% of those receiving placebo. No significant differences between geriatric patients and younger patients regarding bleeding events in the drotrecogin group were found. No non-bleeding side-effects were observed. A second study, encompassing approximately 1700 adult patients, was completed in 2011 and showed a comparable side-effect profile.
The Kuril Islands form part of the ring of tectonic instability encircling the Pacific Ocean referred to as the Ring of Fire. The islands themselves are summits of stratovolcanoes that are a direct result of the subduction of the Pacific Plate under the Okhotsk Plate, which forms the Kuril Trench some 200 kilometres (124 mi) east of the islands. The chain has around 100 volcanoes, some 40 of which are active, and many hot springs and fumaroles. There is frequent seismic activity, including a magnitude 8.5 earthquake in 1963 and one of magnitude 8.3 recorded on 15 November 2006, which resulted in tsunami waves up to 1.5 metres (5 ft) reaching the California coast. Raikoke Island, near the centre of the archipelago, has an active volcano which erupted again in June 2019, with emissions reaching 13,000 m (42,651 ft). The climate on the islands is generally severe, with long, cold, stormy winters and short and notoriously foggy summers. The average annual precipitation is 40 to 50 inches (1,020 to 1,270 mm), a large portion of which falls as snow. The Köppen climate classification of most of the Kurils is subarctic (Dfc), although Kunashir is humid continental (Dfb). However, the Kuril Islands' climate resembles the subpolar oceanic climate of southwest Alaska much more than the hypercontinental climate of Manchuria and interior Siberia, as precipitation is heavy and permafrost completely absent.
The International System of Units (SI) unit of radioactive activity is the becquerel (Bq), named in honor of the scientist Henri Becquerel. One Bq is defined as one transformation (or decay or disintegration) per second. An older unit of radioactivity is the curie, Ci, which was originally defined as "the quantity or mass of radium emanation in equilibrium with one gram of radium (element)". Today, the curie is defined as 3.7×1010 disintegrations per second, so that 1 curie (Ci) = 3.7×1010 Bq. For radiological protection purposes, although the United States Nuclear Regulatory Commission permits the use of the unit curie alongside SI units, the European Union European units of measurement directives required that its use for "public health ... purposes" be phased out by 31 December 1985. Absorbed dose is measured in grays (Gy), while equivalent and effective doses are expressed in sieverts (Sv).
The most commonly used synthetic membrane devices (modules) are flat sheets/plates, spiral wounds, and hollow fibers. Flat membranes used in filtration and separation processes can be enhanced with surface patterning, where microscopic structures are introduced to improve performance. These patterns increase surface area, optimize water flow, and reduce fouling, leading to higher permeability and longer membrane lifespan. Research has shown that such modifications can significantly enhance efficiency in water purification, energy applications, and industrial separations. Flat plates are usually constructed as circular thin flat membrane surfaces to be used in dead-end geometry modules. Spiral wounds are constructed from similar flat membranes but in the form of a "pocket" containing two membrane sheets separated by a highly porous support plate. Several such pockets are then wound around a tube to create a tangential flow geometry and to reduce membrane fouling. Hollow fiber modules consist of an assembly of self-supporting fibers with dense skin separation layers, and a more open matrix helping to withstand pressure gradients and maintain structural integrity. The hollow fiber modules can contain up to 10,000 fibers ranging from 200 to 2500 μm in diameter; The main advantage of hollow fiber modules is the very large surface area within an enclosed volume, increasing the efficiency of the separation process.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
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.