freeze-thaw raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-09-09 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Purity assay | RP-HPLC, UV 214 nm | Typical research grade 95 percent or higher |
| Mass confirmation | ESI-MS or MALDI-TOF | Compared with theoretical value |
| Main degradation route | Methionine oxidation | Sulfoxide formation in solution |
| Powder storage | -20 °C, desiccated | Amber vial, minimal headspace |
| Working solution | Sterile water or saline | Prepare fresh; avoid repeated thawing |
Solid material is normally kept at minus 20 degrees Celsius in a sealed, desiccated container. Reconstituted solutions are less stable and are usually divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of activity. Light exposure is minimized by using amber glassware or foil wrapping. Published stability data for this peptide are sparse, so recommended storage conditions rest mainly on general practice for short synthetic peptides rather than on dedicated study.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
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.
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.
=== Literature === The medal for the Nobel Prize in Literature is given by the Swedish Academy. The reverse of the medal depicts a ' ... young man sitting under a laurel tree who, enchanted, listens to and writes down the song of the Muse'. The 1923 recipient of the literature medal, W. B. Yeats wrote in his 1925 book The Bounty of Sweden that the medal was " ... charming, decorative, academic design, French in manner, a work of the nineties. It shows a young man listening to a Muse, who stands young and beautiful with a great lyre in her hand, and I think as I examine it, 'I was good-looking once like that young man, but my unpractised verse was full of infirmity, my Muse old as it were; and now I am old and rheumatic, and nothing to look at, but my Muse is young". It is inscribed "Inventas vitam iuvat excoluisse per artes" ("It is beneficial to have improved (human) life through discovered arts") an adaptation of "inventas aut qui vitam excoluere per artes" from line 663 from book 6 of the Aeneid by the Roman poet Virgil. A plate below the figures is inscribed with the name of the recipient. The text "ACAD. SUEC." denoting the Swedish Academy is also inscribed on the reverse. It was designed by Erik Lindberg and is manufactured by Svenska Medalj in Eskilstuna.
Peppermint was first identified in Hertfordshire, England, by a Dr. Eales, a discovery which John Ray published 1696 in the second edition of his book Synopsis Methodica Stirpium Britannicarum. He initially gave it the name Mentha spicis brevioribus et habitioribus, foliis Mentha fusca, sapore fervido piperis and later in his 1704 volume Historia Plantarum he called it Mentha palustris or Peper–Mint. The plant was then added to the London Pharmacopoeia under the name Mentha piperitis sapore in 1721. It was given the name Mentha piperita in 1753 by Carl Linnaeus in his Species Plantarum Volume 2. Linnaeus treated peppermint as a species, but it is now agreed to be a hybrid between Mentha aquatica and Mentha spicata, with M. spicata itself also being considered by some authors to be a hybrid between Mentha longifolia and Mentha suaveolens. Peppermint is a herbaceous, rhizomatous, perennial plant that grows to be 30–90 cm (12–35 in) tall, with smooth stems, square in cross section. The rhizomes are wide-spreading and fleshy, and bear fibrous roots. The leaves can be 4–9 cm (1.6–3.5 in) long and 1.5–4 cm (0.59–1.57 in) broad. They are dark green with reddish veins, with an acute apex and coarsely toothed margins. The leaves and stems are usually slightly fuzzy. The flowers are purple, 6–8 mm (0.24–0.31 in) long, with a four-lobed corolla about 5 mm (0.20 in) diameter; they are produced in whorls (verticillasters) around the stem, forming thick, blunt spikes. Flowering season lasts from mid- to late summer.
Shānghán Zábìng Lùn (傷寒雜病論), or The Treatise on Cold Damage and Miscellaneous Diseases, is the first Chinese monograph on diseases by Zhang Zhongjing. The original work is lost, but most of its contents are preserved in two extant works called Shānghán Lùn (傷寒論; "The Treatise on Cold Damage") and Jīnguì Yàolüè (金匱要略; "Essential Prescriptions from the Golden Chamber"). The first work primarily addresses externally triggered conditions while the latter work describes internally generated conditions. Zhang's specialized chapter on xiāo kě is found in Shānghán Lùn and Jīnguì Yàolüè. Nine subsections and nine formulae (herbal remedies) on wasting-thirst were recorded. The text proposed a theory of "three wasting-thirsts": upper- (associated with the lungs), middle- (associated with the stomach), and lower- (associated with the kidneys), all three of which shared excessive urine and thirst as symptoms. This theory was later expanded through the works of Liu Wansu (1120–1200 AD) and Wang Kentang (1549–1613 AD). According to Liu, "lower wasting-thirst" attributed to "kidney-yin deficiency" was associated with sweet urine (glycosuria). This may indicate differentiation akin to modern-day differentiation of diabetes mellitus and diabetes insipidus.
=== Measurement === As almost all DHEA is derived from the adrenal glands, blood measurements of DHEA-S/DHEA are useful to detect excess adrenal activity as seen in adrenal cancer or hyperplasia, including certain forms of congenital adrenal hyperplasia. Women with polycystic ovary syndrome tend to have elevated levels of DHEA-S.
=== Hair loss === Minoxidil is used for the treatment of hair loss. It is mainly used topically, but in more recent years, it also being used at low doses orally and to a lesser extent sublingually. The drug is effective in helping promote hair growth in both men and women with androgenic alopecia (androgen-dependent pattern hair loss). It works by increasing hair counts as well as by thickening individual hair follicles. Minoxidil is less effective when the area of hair loss is large. In addition, its effectiveness has largely been demonstrated in younger men who have experienced hair loss for less than 5 years. Minoxidil use is indicated for central (vertex) hair loss only. Minoxidil must be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth. Its benefits are tangible but fully reversible, with discontinuation following long-term treatment resulting in rapid hair loss and similar hair density as placebo at 24 weeks post-discontinuation. As such, minoxidil does not appear to prevent hair loss long term. Low-dose oral minoxidil (LDOM) is used off-label against hair loss and to promote hair regrowth. Oral minoxidil is an effective and well-tolerated treatment alternative for patients having difficulty with topical formulations. It is notable in this regard that topical minoxidil for hair loss has very low compliance rates, with almost all users discontinuing it after 1 year of use. Consensus statements provide guidance on use of low-dose oral minoxidil for hair loss.
Sources: en.wikipedia.org
Vitamin D: insufficiency is common in diabetics. Observational studies show that serum vitamin D is inversely associated with biomarkers of diabetes; impaired insulin secretion, insulin resistance, and glucose intolerance. It has been suggested that vitamin D may induce beneficial effects on diabetic complications by modulating differentiation and growth of pancreatic β-cells and protecting these cells from apoptosis, thus improving β-cells functions and survival. In particular, vitamin D supplementation has been shown to have positive effects on people with type 1 diabetes. Vitamin D has also been suggested to act on immune system and modulate inflammatory responses by influencing proliferation and differentiation of different immune cells., Moreover, deficiency of vitamin D may contribute to diabetic complications by inducing hyperparathyroidism, since elevated parathyroid hormone levels are associated with reduced β-cells function, impaired insulin sensitivity, and glucose intolerance. Finally, vitamin D may reduce the risk of vascular complications by modulating lipid profile. Antioxidants may have beneficial effects on diabetic complications by reducing blood pressure, attenuating oxidative stress and inflammatory biomarkers, improving lipid metabolism, insulin-mediated glucose disposal, and by enhancing endothelial function. Vitamin C has been proposed to induce beneficial effects by two other mechanisms.
Using any part of a living organism Protein purification involves the isolation of a specific protein of interest from a complex mixture of proteins, often obtained from homogenized cells or tissues. Using parts derived from multicellular organisms (cell culture, tissue culture, and more) In vitro fertilization is used to allow spermatozoa to fertilize eggs in a culture dish before implanting the resulting embryo or embryos into the uterus of the prospective mother. In vitro diagnostics refers to a wide range of medical and veterinary laboratory tests that are used to diagnose diseases and monitor the clinical status of patients using samples of blood, cells, or other tissues obtained from a patient. In vitro pharmacological testing has been used to characterize specific adsorption, distribution, metabolism, and excretion processes of drugs or general chemicals inside a living organism; for example, Caco-2 cell experiments can be performed to estimate the absorption of compounds through the lining of the gastrointestinal tract; The partitioning of the compounds between organs can be determined to study distribution mechanisms; Suspension or plated cultures of primary hepatocytes or hepatocyte-like cell lines (Hep G2, HepaRG) can be used to study and quantify metabolism of chemicals. These ADME process parameters can then be integrated into so called "physiologically based pharmacokinetic models" or PBPK. Cellular models of neurodegenerative diseases allow different ways to probe the health of the mitochondria in the cell. Using cellular or subcellular extracts (e.g.
Tolerance to psilocybin appears after a single dose and dissipates dissipates after a few days. A cross-tolerance can develop between psilocybin and other classical psychedelics such as LSD, mescaline and DOM. Repeated use of psilocybin does not lead to physical dependence or drug withdrawal. Despite the rapid onset of tolerance, rates of self-administration in Rhesus macaques are low, which usually indicates a low abuse potential. A 2008 study concluded that, based on U.S. data from 2000 to 2002, adolescent-onset usage of hallucinogenic drugsdid not increase the risk of drug dependence in adulthood; this was in contrast to adolescent usage of cannabis, cocaine, inhalants, anxiolytic medicines, and stimulants, all of which were associated with "an excess risk of developing clinical features associated with drug dependence". Multiple studies in 2010 ranked the relative harm of psilocybin mushrooms below all other drugs in a selection of 19 recreational drugs, including alcohol, cannabis, cocaine, ecstasy, heroin, and tobacco.
Braun's lipoprotein (BLP, Lpp, murein lipoprotein, or major outer membrane lipoprotein) was first identified by V. Braun and K. Rehn in 1969, it was the first Lipoprotein identified prompting much further study in this area. It is found in some gram-negative cell walls, is one of the most abundant membrane proteins; its molecular weight is about 7.2 kDa. It is bound at its C-terminal end (a lysine) by a covalent bond to the peptidoglycan layer (specifically to diaminopimelic acid molecules) and is embedded in the outer membrane by its hydrophobic head (a cysteine with lipids attached). BLP tightly links the two layers and provides structural integrity to the outer membrane.
Flicker noise is electronic noise with a 1/ƒ frequency spectrum; as f increases, the noise decreases. Flicker noise arises from a variety of sources, such as impurities in a conductive channel, generation, and recombination noise in a transistor due to base current, and so on. This noise can be avoided by modulation of the signal at a higher frequency, for example, through the use of a lock-in amplifier.
Sources: en.wikipedia.org
Field ration – a field ration, combat ration or ration pack is a canned or pre-packaged meal, easily prepared and eaten, transported by military troops on the battlefield. Humanitarian daily ration Individual Meal Pack Meal, Ready-to-Eat Military rations
== Atmospheric occurrence == In atmospheric sciences, O4 usually refers to the collision-induced complex arising from interactions between two O2 molecules. Also called O2-O2 dimers, these unstable dimers exhibit distinct collision-induced absorption (CIA) bands in the UV and visible ranges. Because molecular oxygen is well-mixed and the distribution is well known, the concentration of O2-O2 dimers is predictable and primarily dependent on air density. Since clouds change how light passes through the atmosphere, the strength of the O2-O2 absorption can be used to detect their presence and height. Therefore, satellite measurements of spectral radiance within the O2-O2 absorption bands can be used to calculate cloud properties such as cloud-top pressure and cloud fraction globally. The same absorption features, including bands at 360, 477 and 577 nm, are used to derive aerosol profiles in atmospheric optical spectroscopy, where the predictable distribution of O2 provides useful constraint in aerosol inversion techniques and radiative transfer models.
=== The Major Intrinsic Protein Family (TC# 1.A.8) === The MIP family is large and diverse, possessing thousands of members that form transmembrane channels. These channel proteins function in transporting water, small carbohydrates (e.g., glycerol), urea, NH3, CO2, H2O2 and ions by energy-independent mechanisms. For example, the glycerol channel, FPS1p of Saccharomyces cerevisiae mediates uptake of arsenite and antimonite. Ion permeability appears to occur through a pathway different than that used for water/glycerol transport and may involve a channel at the 4 subunit interface rather than the channels through the subunits. MIP family members are found ubiquitously in bacteria, archaea and eukaryotes. Phylogenetic clustering of the proteins is primarily based according to phylum of the organisms of origin, but one or more clusters are observed for each phylogenetic kingdom (plants, animals, yeast, bacteria and archaea). MIPs are classified into five subfamilies in higher plants, including plasma membrane (PIPs), tonoplast (TIPs), NOD26-like (NIPs), small basic (SIPs) and unclassified X (XIPs) intrinsic proteins. One of the plant clusters includes only tonoplast (TIP) proteins, while another includes plasma membrane (PIP) proteins.
An application of the Wittig-Still rearrangement in the context of natural product synthesis can be seen in Still's 1979 formal synthesis of the Cecropia juvenile hormone. The organotin-substituted ether that serves as the substrate for the rearrangement was readily prepared by bis-alkylation of the corresponding diol with iodomethyltributyltin. Treatment of this compound with two equivalents of n-butyllithium at low temperature resulted in transmetalation, initiating a double 2,3-sigmatropic rearrangement to give the bis-homoallylic alcohol product in 79% yield. Notably, this rearrangement is highly stereoselective with regard to the geometry of the trisubstituted olefins, giving exclusively the (Z,Z)-isomer shown.
For voluntary and charitable services to the community in Limavady, County Londonderry. David Gregory Snook. Reading Volunteer, Hampton Primary School, Herne Bay, Kent. For services to Education. Versha Sood-Mahindra. Lately Dementia Lead, BUPA. For services to Community Cohesion and to People with Dementia in Cardiff. Zoe Donna Sookun. Project Manager, Network Rail. For services to the Railway and to Rail Aid for Ukraine. Denise Speight. Chargehand Cleaner, Newcastle City Council. For services to Local Government. Charlotte Jessica Stacey. On Call Firefighter, Oxfordshire Fire and Rescue Service. For services to the community in Oxfordshire. Margaret Pearl Sterling. Teaching Associate, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast. For services to Higher Education in Northern Ireland. Eileen Linda Stewart. Manager, Armagh Business Centre. For services to Entrepreneurship, to Economic Regeneration and to the community in Armagh, Northern Ireland. Gloria Ann Stewart. For services to the community in Sheffield, South Yorkshire. Sheena Stewart. Lately Warden, Chalmers Court Sheltered Housing Complex, Inverarary. For services to the community in Mid-Argyll. Allan Stokoe. For services to the community in Eldon, North Yorkshire. Dr Jill Mary Stoner. Chair, Cromarty Care Project. For services to the community in Cromarty, Ross and Cromarty. Jan Tallis. Founding Chair, Community Schools Trust. For services to Children and Families in the London Borough of Newham. Robert Sherwin Taylor. For services to the community in Shipbourne, Kent.
Sources: en.wikipedia.org
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.
The main chemical risks are methionine oxidation and backbone hydrolysis in solution. Moisture and repeated temperature cycling accelerate both processes. Dry powder held cold and desiccated is considerably more stable than any reconstituted preparation.
It holds a medicine registration in Russia, where it has been used clinically for decades. In most other countries it is treated as a research chemical. That split explains the uneven distribution of clinical literature.
Registered medical products are most often 0.1% nasal drops. Research suppliers ship lyophilized powder, usually in milligram quantities, which is dissolved before use. The active peptide is the same in both cases; presentation and excipients differ.