If you have been reading about counterion 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.
Updated 2025-11-26. Numbers and descriptions here follow the published literature rather than marketing material.
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.
Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
| Property | Value | Notes |
|---|---|---|
| Typical purity | ≥95% by HPLC | Research-grade material |
| Detection wavelength | 214 nm | Peptide bond absorbance |
| Reconstitution medium | Sterile water or saline | Prepare fresh or aliquot immediately |
| Storage (solution) | -80 °C, single-use aliquots | Avoid repeated freeze-thaw cycles |
| Common salt form | Acetate or trifluoroacetate | Affects mass and solubility |
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.
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.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
Verification of a supplied batch generally combines a certificate of analysis with independent testing, because certificates are self-reported documents. A typical package includes a chromatographic trace, a mass spectrum, and a stated water or counter-ion content. Batch-to-batch consistency matters more than a single purity figure when results are compared across experiments. No single mandatory standard governs research-grade peptide release, so laboratories are expected to define their own acceptance criteria. Residual trifluoroacetate from purification is a frequently overlooked counter-ion.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
Levobunolol (trade names AKBeta, Betagan, Vistagan, among others) is a non-selective beta blocker. It is used topically in the form of eye drops to manage ocular hypertension (high pressure in the eye) and open-angle glaucoma.
=== October === 1 October – Prime Minister Rishi Sunak announces £20m of levelling up funding to help regenerate seven Scottish towns that are described as having been overlooked. 2 October – ScotRail begins a six months trial during which peak time train fares are scrapped. 3 October – Aberdeen City Council says that reinforced autoclaved aerated concrete (RAAC) is likely to have been used in hundreds of properties in the city. 4 October – Police Scotland pays £60,000 compensation to four traffic officers told to shave off their beards before the force implemented its delayed proposals for a clean shaven policy. 5 October – Labour's Michael Shanks wins the Rutherglen and Hamilton West by-election. 6 October – Police Scotland scraps plans to recruit an extra 200 officers in January 2024 as it attempts to save costs following a projected overspend of £19m. 7 October – The Met Office issues an amber weather alert for heavy rain in Scotland, while roads and train services are disrupted by flooding. Ten people are airlifted to safety after heavy rain causes landslides on two roads in Argyll. 9 October – Bernard Cowan, a grandfather who grew up in the Glasgow area, is confirmed as one of the people killed during a series of attacks launched by Hamas against Israel on 7 October. Humza Yousaf, the First Minister of Scotland, condemns the attacks and expresses concern for his in-laws, who are "trapped" in Gaza after travelling there to visit relatives. The Scottish Medicines Consortium (SMC) approves the weight loss drug semaglutide for use by NHS Scotland.
=== Need for stoichiometric control === There are two important aspects with regard to the control of molecular weight in polymerization. In the synthesis of polymers, one is usually interested in obtaining a product of very specific molecular weight, since the properties of the polymer will usually be highly dependent on molecular weight. Molecular weights higher or lower than the desired weight are equally undesirable. Since the degree of polymerization is a function of reaction time, the desired molecular weight can be obtained by quenching the reaction at the appropriate time. However, the polymer obtained in this manner is unstable, in that it leads to changes in molecular weight because the ends of the polymer molecule contain functional groups that can react further with each other. This situation is avoided by adjusting the concentrations of the two monomers so that they are slightly nonstoichiometric. One of the reactants is present in slight excess. The polymerization then proceeds to a point at which one reactant is completely used up and all the chain ends possess the same functional group of the group that is in excess. Further polymerization is not possible, and the polymer is stable to subsequent molecular-weight changes. Another method of achieving the desired molecular weight is by addition of a small amount of monofunctional monomer, a monomer with only one functional group.
=== October === 1 October The price of an average energy bill rises by £149 per year to £1,717. Buckingham Palace announces that Princess Beatrice of York is expecting her second child. A new law requires hospitality sector workers in England, Wales and Scotland to receive all money from tips left by customers. 2 October – The first flight chartered by the UK government to evacuate British nationals from Lebanon following the increase in tension between Hezbollah and Israel arrives in the UK with 150 people on board. 3 October – The UK announces that it will give up sovereignty of the Chagos Islands to Mauritius, subject to finalisation of a treaty. 4 October A Royal Navy investigation finds that women in the Submarine Service have faced misogyny, bullying and other unacceptable behaviour. First Sea Lord Admiral Sir Ben Key, who heads the Royal Navy, apologises and describes such behaviour as "intolerable". The UK government pledges £22bn in investment over the next 25 years for projects to capture and store carbon emissions from energy, industry and hydrogen production. Data published by the Independent Schools Council, the body representing private schools in the UK, indicates a 4.6% fall in the number of private students starting in private sector secondary education in September 2024. 395 migrants cross the English Channel in small boats from France to the UK. 5 October A large pro-Palestinian protest, involving tens of thousands of marchers, takes place in central London, coinciding with the first anniversary of the 7 October attacks.
Bruker develops and delivers a wide variety of professional and scientific analysis devices including mass spectrometers, single-Crystal and powder X-ray diffractometers, X-ray tomography devices, NMR spectroscopy devices, fluorescence microscopes, raman spectroscopes, atomic-force microscopes, and profilometers.
Sources: en.wikipedia.org
Her two manuscripts on form A DNA reached Acta Crystallographica in Copenhagen on 6 March 1953, one day before Crick and Watson had completed their model. The X-ray diffraction images collected by Gosling and Franklin provided the best evidence for the helical nature of DNA. Before this, both Linus Pauling, Watson, and Crick had generated erroneous models with the chains inside and the bases pointing outwards. Her experimental results provided estimates of the water content of DNA crystals, and these results were most consistent with the three sugar-phosphate backbones being on the outside of the molecule. Franklin's X-Ray photograph showed that the backbones had to be on the outside. Although she at first insisted vehemently that her data did not force one to conclude that DNA has a helical structure, in the drafts she submitted in 1953 she argues for a double helical DNA backbone. Building on her manuscripts, she discovered that form A DNA had antiparallel backbones, which supported the double helical structure of DNA. She did this through identification of the space group for DNA crystals. This would go to help Watson and Crick decide to look for DNA models with two antiparallel polynucleotide strands. In summary, Watson and Crick had three sources for Franklin's unpublished data: 1) her 1951 seminar, attended by Watson, 2) discussions with Wilkins, who worked in the same laboratory with Franklin, 3) a research progress report that was intended to promote coordination of Medical Research Council–supported laboratories.
=== Pregnancy and breastfeeding === Ixazomib and lenalidomide are teratogenic in animal studies. The latter is contraindicated in pregnant women, making this therapy regimen unsuitable for this group. It is not known whether ixazomib or its metabolites pass into the breast milk.
They built on the character of the Aperture Science facility, providing a deeper story for GLaDOS and Aperture's CEO Cave Johnson, as well as developing several concepts for "personality cores" that ultimately led to the creation of Wheatley. Portal 2 received similar acclaim to its predecessor at launch, garnering a Metacritic score of 95 out of 100. Valve has continued to support the game through the release of two separate downloadable content packages, one introducing a new co-operative campaign, and a second that incorporated an easy-to-learn level editor that allowed players to make their own test chambers and share these through the Steam Workshop to others. An alternate version of Portal 2 designed for educational use was developed for Valve's Steam for Schools program, and was made available for free. While experimenting with VR systems in 2017, Valve attempted to implement Portal-like gameplay, but early playtesters found the game's titular mechanic disorienting in VR. Valve instead returned to the Half-Life series and released Half-Life: Alyx in 2020. In April 2022, Erik Wolpaw urged Valve to make Portal 3, saying, "I am... not getting any younger. We are reaching the point where – it's crazy to think – [we're] literally going to be too old to work on Portal 3. So we should just do it." In September, Ellen McLain also called for Portal 3, stating that she was willing to star in it, and asked fans to "write in. Email Valve. You've got my blessing".
18 Poems, The Sunday Referee; Parton Bookshop, 1934 Portrait of the Artist as a Young Dog, London: Dent, 1940 Deaths and Entrances, London: Dent, 1946 A Child's Christmas in Wales, New Directions, 1955 The Collected Poems of Dylan Thomas: The New Centenary Edition. Ed. with Introduction and annotations by John Goodby. London: Weidenfeld & Nicolson, 2014 The Notebook Poems 1930–34, ed. Ralph Maud. London: Dent, 1989 Dylan Thomas: The Broadcasts, ed. Ralph Maud. London: Dent, 1991 Dylan Thomas: The Filmscripts, ed. John Ackerman. London: Dent, 1995 Dylan Thomas: Early Prose Writings, ed. Walford Davies. London: Dent, 1971 Collected Stories, ed. Walford Davies. London: Dent, 1983 Under Milk Wood: A Play for Voices, ed. Walford Davies and Ralph Maud. London: Dent, 1995 On the Air with Dylan Thomas: The Broadcasts, ed. R. Maud. New York: New Directions, 1991
Holyhead's arts centre, the Ucheldre Centre, is located in the chapel of an old convent belonging to the order of the Bon Sauveur. It holds regular art exhibitions, performances, workshops and film screenings. Holyhead Library is located in the old market hall. The Holyhead Maritime Museum is housed in what is claimed to be Wales's oldest lifeboat house. The lifeboat station was established in 1828. The 1927 National Eisteddfod was held in the town. Holyhead High School (previously County Secondary school) was the first comprehensive school in the UK. According to the United Kingdom Census 2001, 47% of the residents in the town can speak Welsh. The highest percentage of speakers is in the 15-year-old age group, of whom 66% can speak the language. According to the 2011 Census, of those in the community who were born in Wales, 52.2% of the population could speak Welsh. The town's main football team is called Holyhead Hotspur, and they play in the Cymru North, the second tier of Welsh football, with their reserves playing in the Gwynedd League. Caergybi F.C. plays in the sixth tier Anglesey League. Holyhead Sailing Club provides members with facilities for sailing and kayaking with swinging moorings, a dinghy park and a clubhouse with a restaurant and bar. It is on Newry Beach in the historic port of Holyhead. Holyhead & Anglesey Amateur Boxing Club was founded on 1 April 2012, located in Vicarage Lane, Holyhead. The club is open to anyone over the age of 10, having a class for male and female trainees.
Sources: en.wikipedia.org
In 2013, researchers demonstrated graphene's high mobility in a detector that allows broad band frequency selectivity ranging from the THz to IR region (0.76–33 THz) A separate group created a terahertz-speed transistor with bistable characteristics, which means that the device can spontaneously switch between two electronic states. The device consists of two layers of graphene separated by an insulating layer of boron nitride a few atomic layers thick. Electrons move through this barrier by quantum tunneling. These new transistors exhibit negative differential conductance, whereby the same electric current flows at two different applied voltages. In June, an 8 transistor 1.28 GHz ring oscillator circuit was described. The negative differential resistance experimentally observed in graphene field-effect transistors of conventional design allows for construction of viable non-Boolean computational architectures. The negative differential resistance—observed under certain biasing schemes—is an intrinsic property of graphene resulting from its symmetric band structure. The results present a conceptual change in graphene research and indicate an alternative route for graphene applications in information processing. In 2013 researchers created transistors printed on flexible plastic that operate at 25 gigahertz, sufficient for communications circuits and that can be fabricated at scale. The researchers first fabricated non-graphene-containing structures—the electrodes and gates—on plastic sheets.
Bacterial Inclusion Bodies Contain Amyloid-Like Structure at SciVee Amyloid Cascade Hypothesis Amyloid: Journal of Protein Folding Disorders web page Role of anesthetics in Alzheimer's disease: Molecular details revealed
But Geoffrey Pullum, the coiner of the term snowclone, considers that it is only a "lexical word-formation analog". Martha Brockenbrough, the founder of The Society for the Promotion of Good Grammar, said that no one should aspire to write with cliches and that although they do help to get a lot of complicated things across in few words, they are not a good way to get people to keep reading what you're writing.
== Mechanism == A CI experiment involves the use of gas phase acid-base reactions in the chamber. Some common reagent gases include: methane, ammonia, water and isobutane. Inside the ion source, the reagent gas is present in large excess compared to the analyte. Electrons entering the source will mainly ionize the reagent gas because it is in large excess compared to the analyte. The primary reagent ions then undergo secondary ion/molecule reactions (as below) to produce more stable reagent ions which ultimately collide and react with the lower concentration analyte molecules to form product ions. The collisions between reagent ions and analyte molecules occur at close to thermal energies, so that the energy available to fragment the analyte ions is limited to the exothermicity of the ion-molecule reaction. For a proton transfer reaction, this is just the difference in proton affinity between the neutral reagent molecule and the neutral analyte molecule. This results in significantly less fragmentation than does 70 eV electron ionization (EI). The following reactions are possible with methane as the reagent gas.
Sources: en.wikipedia.org
Solid peptide is best kept frozen at about minus 20 degrees Celsius in a sealed container with desiccant. It should be allowed to reach room temperature before opening to prevent condensation. Repeated warming and cooling of the same vial is discouraged.
Reversed-phase liquid chromatography establishes purity, while mass spectrometry confirms molecular mass. The two techniques are normally used together. Retention time alone is not sufficient evidence of identity.
Different counterions change the mass per unit of peptide and can shift chromatographic behavior. Two samples of equal stated purity may therefore not be directly comparable. Reports should specify the counterion whenever quantitative comparisons are made.
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.