This is a working overview of freeze-thaw, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-07-04 and is reviewed periodically as new material appears.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Analog of an ACTH fragment |
| Amino acid length | Seven residues | Met-Glu-His-Phe-Pro-Gly-Pro |
| Origin | Moscow, 1980s | Institute of Molecular Genetics |
| Approved regions | Russia and some neighboring states | Not cleared in Western markets |
| Common trade names | Multiple national brands | Sold as a nasal formulation |
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
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.
==== 8 April ==== In Iran, the Lavan Oil Refinery, located on Lavan Island was struck at around 10 a.m.; a fire ignited. The Iranian authorities denounced the event and stated that it was an act of "cowardice" by the "enemies". Israel denied being involved in the attack. The debris of a drone shot down by Iranian forces killed a 7-year-old child and injured another six members of the child's family in the town of Shushtar in Khuzestan province.
Blood pH is regulated to stay within the narrow range of 7.35 to 7.45, making it slightly basic (compensation). Extra-cellular fluid in blood that has a pH below 7.35 is too acidic, whereas blood pH above 7.45 is too basic. A pH below 6.9 or above 7.8 is usually lethal. Blood pH, partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), and bicarbonate (HCO3−) are carefully regulated by a number of homeostatic mechanisms, which exert their influence principally through the respiratory system and the urinary system to control the acid–base balance and respiration, which is called compensation. An arterial blood gas test measures these. Plasma also circulates hormones transmitting their messages to various tissues. The list of normal reference ranges for various blood electrolytes is extensive.
However, others experience the term "borderline personality disorder" as a pejorative label rather than an informative diagnosis. They report concerns that their self-destructive behavior is incorrectly perceived as manipulative and that the stigma surrounding this disorder limits their access to health care.
Sources: en.wikipedia.org
The Moderna COVID-19 vaccine, manufactured by Moderna since 2020, is a lipid nanoparticle (LNP) encapsulated mRNA-based vaccine that encodes for a full-length, prefusion stabilized spike(S)-2P antigen of SARS-CoV-2 with a transmembrane anchor.
=== Mammography === Molybdenum targets are used in mammography because they produce X-rays in the energy range of 17–20 keV, which is optimal for imaging soft tissues like the breast. The characteristic X-rays emitted from molybdenum provide high contrast between different types of tissues, allowing for the effective visualization of microcalcifications and other subtle abnormalities in breast tissue. This energy range also minimizes radiation dose while maximizing image quality, making molybdenum targets particularly suitable for breast cancer screening.
== Digestibility == Hemp protein, when untreated, is more digestible compared to soy protein. Heat pre-treatment at temperatures above 80 °C may improve the digestibility of both hemp and soy protein, but in untreated (unheated) form hemp protein is more readily digested than the soy one. Dehulled hemp seeds (also known as hemp nuts, hemp kernels or hemp hearts) have a protein digestibility corrected amino acid score (PDCAAS) of 0.66, with lysine being the limiting amino acid (digestibility of 92.1%). With its gluten content as low as 4.78 ppm, hemp is attracting attention as a gluten-free (<20 ppm) food material. Hemp protein is sold in bulk as a powder, in various forms, such as hempseed meal, hemp protein concentrates, and hemp protein isolates. It generally has greenish hue due to the natural pigments in the hemp plant, but the color can vary depending on the specific processing methods used. Unflavored hemp protein powder is commonly available, that is, no additional flavoring is added to the hemp protein, which is usually described as earthy or nutty.
Sources: en.wikipedia.org
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.
It is registered as a medicine in Russia and has been used clinically there for decades. No regulatory agency in Western Europe or North America has approved it for any indication.
Semax corresponds to the four-to-ten fragment of adrenocorticotropic hormone. Because it omits the first three residues, it lacks the adrenal-stimulating action of the full hormone.
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.