reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | ACTH(4-7) analogue |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Free N terminus, unmodified side chains |
| Molecular weight | 813.9 Da | Free base; salt forms differ |
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility | Freely soluble in water | Hydrophilic; polar solvents preferred |
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
=== 2002–2005: Lilo & Stitch, The Ring, and television success === Chase's international profile expanded significantly in 2002. She was cast as the voice of Lilo Pelekai, a quirky and lonely Hawaiian girl who befriends a destructive alien fugitive, in the Walt Disney Animation Studios feature Lilo & Stitch. The film was a critical and commercial triumph, grossing over $273 million worldwide. Chase's voice performance was highly praised for its emotional authenticity and comedic timing; she was subsequently awarded the Outstanding Voice Acting in an Animated Feature at the 30th Annie Awards in 2003. She reprised the role of Lilo in the direct-to-video film Stitch! The Movie (2003) and the subsequent television series Lilo & Stitch: The Series, which aired on the Disney Channel from 2003 to 2006. Another voice acting role followed that year in Hayao Miyazaki's acclaimed animated fantasy film Spirited Away, that had a Disney-produced English-language dub where Chase provided the voice for protagonist Chihiro Ogino. Spirited Away later won the Academy Award for Best Animated Feature. Later in 2002, Chase starred as Samara Morgan in the supernatural horror film The Ring, a remake of the 1998 Japanese film Ring. Playing a malevolent, drowned child who curses a videotape, Chase required extensive prosthetic makeup and performed physically demanding stunt work in the role. Her portrayal gained wide notice in early 2000s pop culture, and the character of Samara became an iconic cinematic villain. At the 2003 MTV Movie Awards, Chase won the Best Villain award.
=== Miniature linear quadrupole mass filter === The linear quadrupole mass filter or quadrupole mass analyzer is one of the most popular mass analyzer. The mini-quadrupole has been used as a single analyzer or in arrays of identical mass analyzers. The quadrupole array has rods of 0.5mm radius and 10mm long while another one with rods of 1mm radius and 25mm long. These mini quadrupole were developed and characterized at a radio frequency (RF) higher than 11 MHz. Volatile organic compounds were ionized by electron ionization and were characterized with unit resolution. Micromachining was applied to produce a much smaller V-groove quadrupole.
=== Tertiary packaging === The outermost package, known as tertiary packaging, makes it easier to handle, store, and distribute both primary and secondary packages in bulk safely, providing further protection of the product while creating an easy way to transport large quantities of materials. The most familiar type of tertiary packaging comprises a wrapped pallet of corrugated cases.
In the Constituent Assembly of India debates between 1946 and 1949, India's founders strongly preferred birthplace citizenship, viewing it as more democratic than basing rights on race or descent. While India’s 1950 constitution originally offered palliative measures to those displaced by the Partition, the Citizenship Act of 1955 formally established birthplace as the foundation for Indian citizenship. More recently, India's new citizenship laws have shifted to favour bloodline over birthplace, creating legal obstacles for new or marginalised groups to experience substantive equality. The Lok Sabha, India’s lower house of parliament, has 543 members directly elected by citizens aged 18 and older, with specific seats reserved to ensure fair representation for Scheduled Castes and Scheduled Tribes. However, its legislative productivity has significantly declined over the decades, with the average number of working days dropping from 121 days per year in the 1950s to 68 days between 2000 and 2023. In addition, more meeting time is lost to disruptions. The Rajya Sabha, India’s upper house of parliament, serves as a federal chamber where state legislatures elect members through a system that balances state size with minimum representation for smaller regions. However, historical data shows that most members serve only a single term, suggesting that political party leaders sometimes use these seats to reward favourites.
Sources: en.wikipedia.org
== MrBayes software == MrBayes is a free software tool that performs Bayesian inference of phylogeny. It was originally written by John P. Huelsenbeck and Frederik Ronquist in 2001. As Bayesian methods increased in popularity, MrBayes became one of the software of choice for many molecular phylogeneticists. It is offered for Macintosh, Windows, and UNIX operating systems and it has a command-line interface. The program uses the standard MCMC algorithm as well as the Metropolis coupled MCMC variant. MrBayes reads aligned matrices of sequences (DNA or amino acids) in the standard NEXUS format. MrBayes uses MCMC to approximate the posterior probabilities of trees. The user can change assumptions of the substitution model, priors and the details of the MC³ analysis. It also allows the user to remove and add taxa and characters to the analysis. The program includes, among several nucleotide models, the most standard model of DNA substitution, the 4x4 also called JC69, which assumes that changes across nucleotides occur with equal probability. It also implements a number of 20x20 models of amino acid substitution, and codon models of DNA substitution. It offers different methods for relaxing the assumption of equal substitutions rates across nucleotide sites. MrBayes is also able to infer ancestral states accommodating uncertainty to the phylogenetic tree and model parameters. MrBayes 3 was a completely reorganized and restructured version of the original MrBayes. The main novelty was the ability of the software to accommodate heterogeneity of data sets.
As the strictest of vegetarian diets, a vegan diet excludes all animal products, and can be accompanied by the abstention from animal-derived products, such as leather shoes and silk clothes. Vegetarian diets pose some difficulties. For vitamin B12, depending on the presence or absence of eggs and dairy products in the diet or other reliable B12 sources, vegetarians or vegans may incur a nutritional deficiency. Packaged and processed foods may contain minor quantities of animal ingredients. While some vegetarians scrutinize product labels for such ingredients, others do not object to consuming them, or are unaware of their presence.
Pizza Hut, LLC is an American multinational pizza restaurant chain and international franchise founded in 1958 in Wichita, Kansas, by brothers Dan and Frank Carney. The chain, headquartered in Plano, Texas alongside KFC, operates 19,974 restaurants worldwide as of 2025. While studying at Wichita State University, the Carneys opened their first location, which quickly expanded to six outlets within a year. The brand began franchising in 1959, and its distinctive building style was designed by Chicagoan architect George Lindstrom in 1963. Pizza Hut experienced significant growth, including the acquisition by PepsiCo in 1977, followed by a spin-off into Tricon Global Restaurants, Inc., later renamed Yum! Brands in 2002, who are the former owners, and later, the acquisition by LongRange Capital and Yum China in 2026.
Methods to diagnose glycogen storage diseases include history and physical examination for associated symptoms, blood tests for associated metabolic disturbances, and genetic testing for suspected mutations. It may also include a non-ischemic forearm test, exercise stress test, or 12-minute walk test (12MWT). Advancements in genetic testing are slowly diminishing the need for biopsy; however, in the event of a VUS and inconclusive exercise tests, a biopsy would then be necessary to confirm diagnosis.
Sub-slab depressurization (soil suction) by increasing under-floor ventilation; Improving the ventilation of the house and avoiding the transport of radon from the basement into living rooms; Installing a radon sump system in the basement; Installing a positive pressurization or positive supply ventilation system. According to the EPA, the method to reduce radon "...primarily used is a vent pipe system and fan, which pulls radon from beneath the house and vents it to the outside", which is also called sub-slab depressurization, active soil depressurization, or soil suction. Generally indoor radon can be mitigated by sub-slab depressurization and exhausting such radon-laden air to the outdoors, away from windows and other building openings. "[The] EPA generally recommends methods which prevent the entry of radon. Soil suction, for example, prevents radon from entering your home by drawing the radon from below the home and venting it through a pipe, or pipes, to the air above the home where it is quickly diluted" and the "EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently". Positive-pressure ventilation systems can be combined with a heat exchanger to recover energy in the process of exchanging air with the outside, and simply exhausting basement air to the outside is not necessarily a viable solution as this can actually draw radon gas into a dwelling.
Sources: en.wikipedia.org
For given RTD, there is an upper limit on the amount of mixing that can occur, called the maximum mixedness, and this determines the achievable yield. A continuous stirred-tank reactor can be anywhere in the spectrum between completely segregated and perfect mixing. The RTD of chemical reactors can be obtained by CFD simulations. The very same procedure that is performed in experiments can be followed. A pulse of inert tracer particles (during a very short time) is injected into the reactor. The linear motion of tracer particles is governed by Newton's second law of motion and a one-way coupling is stablished between fluid and tracers. In one-way coupling, fluid affects tracer motion by drag force while tracer does not affect fluid. The size and density of tracers are chosen so small that the time constant of tracers becomes very small. In this way, tracer particles exactly follow the same path as the fluid does.
Soybeans have the smallest sample food that provide complete protein, smaller than for several animal foods. Food samples for nuts, seeds, beans, and peas are bigger than one of chicken, and in case of rice, the sample is simply unpractical - the known fact is that cereals are not the main source of proteins.
On July 15, 2014, Researchers from the University of Essex both captured and delivered its graduation ceremonies in 4K UHDTV over the internet using H.264 in realtime. The 4K video stream was published at 8 Mbit/s and 14 Mbit/s for all its 11 ceremonies, with people viewing in from countries such as Cyprus, Bulgaria, Germany, Australia, UK, and others. On 4 September 2014, Canon Inc. announced that a firmware upgrade would add Rec. 2020 color space support to their EOS C500 and EOS C500 PL camera models and their DP-V3010 4K display. On 4 September 2014, Microsoft announced a firmware update for the Microsoft Lumia 1020, 930, Icon, and 1520 phones that adds 4K video recording. The update was later released by the individual phone carriers over the following weeks and months after the announcement. On September 5, 2014, the Blu-ray Disc Association announced that the 4K Blu-ray Disc specification supports 4K video at 60 fps, High Efficiency Video Coding, the Rec. 2020 color space, high dynamic range, and 10 bpc color depth. 4K Blu-ray Disc will have a data rate of at least 50 Mbit/s and may include support for 66 GB and 100 GB discs. 4K Blu-ray Disc began licensing in 2015, with 4K Blu-ray Disc players released late that year. On September 5, 2014, DigitalEurope released an Ultra HD logo for companies that meet their technical requirements. On September 11, 2014, satellite operator SES announced the first Ultra HD conditional access-protected broadcast using DVB standards at the IBC show in Amsterdam.
=== Spin column === Spin column-based nucleic acid purification is a method of purifying DNA, RNA or plasmid from a sample using a spin column filter. The method is based on the principle of selectively binding nucleic acids to a solid matrix in the spin column, while other contaminants, such as proteins and salts, are washed away. The conditions are then changed to elute the purified nucleic acid off the column using a suitable elution buffer.
== Adsorption spillover == In the case catalytic or adsorbent systems where a metal species is dispersed upon a support (or carrier) material (often quasi-inert oxides, such as alumina or silica), it is possible for an adsorptive species to indirectly adsorb to the support surface under conditions where such adsorption is thermodynamically unfavorable. The presence of the metal serves as a lower-energy pathway for gaseous species to first adsorb to the metal and then diffuse on the support surface. This is possible because the adsorbed species attains a lower energy state once it has adsorbed to the metal, thus lowering the activation barrier between the gas phase species and the support-adsorbed species. Hydrogen spillover is the most common example of an adsorptive spillover. In the case of hydrogen, adsorption is most often accompanied with dissociation of molecular hydrogen (H2) to atomic hydrogen (H), followed by spillover of the hydrogen atoms present. The spillover effect has been used to explain many observations in heterogeneous catalysis and adsorption.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.
It contains the 4-7 fragment of adrenocorticotropic hormone extended at the C terminus. That truncation removes the region associated with steroidogenic activity. The design intent was to keep neurotrophic properties while avoiding full hormonal effects.
No natural source of the intact heptapeptide is known. It is produced by solid-phase peptide synthesis. Some related ACTH fragments arise as hormone processing products, but the Pro-Gly-Pro extension is a designed addition rather than a natural sequence.
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.