lyophilized 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 2026-01-12. Numbers and descriptions here follow the published literature rather than marketing material.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
The two substrates of this enzyme are estradiol and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are estrone, reduced NADH, and a proton. The enzyme can alternatively use nicotinamide adenine dinucleotide phosphate as its cofactor. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is estradiol-17beta:NAD(P)+ 17-oxidoreductase. Other names in common use include 20alpha-hydroxysteroid dehydrogenase, 17beta,20alpha-hydroxysteroid dehydrogenase, 17beta-estradiol dehydrogenase, estradiol dehydrogenase, estrogen 17-oxidoreductase, and 17beta-HSD. This enzyme participates in androgen and estrogen metabolism.
== External links == Media related to Romanian Revolution of 1989 at Wikimedia Commons Article on justice failing for 942 killed in Revolution on eve of 20th anniversary Video of Nicolae Ceaușescu's final speech in Republican Square Anonymous Photo Essay about the Romanian Revolution of 1989 TV broadcasts from 22 and 23 December 1989 Live TV Broadcast from 22 December 1989 on Hungarian TV (with English subtitles) The Romanian Revolution of December 1989 Academic Article on Feature Films about 1989 Academic Article on Documentaries about 1989
Polar is a 2019 neo-noir action thriller film directed by Jonas Åkerlund and written by Jayson Rothwell, based on Víctor Santos's 2013 graphic novel Polar: Came From the Cold. The film stars Mads Mikkelsen, Vanessa Hudgens, Katheryn Winnick, and Matt Lucas. It revolves around an aging assassin on the verge of retirement who becomes targeted by his employer wanting to cash in on his pension. Polar was released worldwide on Netflix on January 25, 2019. A second film, The Black Kaiser, is in development.
=== Development === In the course of his work on lysozyme, Chain read papers on the enzyme in the British Journal of Experimental Pathology by Alexander Fleming in volumes 3 and 8, and by Florey in volume 11. While doing so he came across Fleming's paper discussing the antibacterial effects of Penicillium notatum mould in volume 10. The erroneous impression given by Fleming that penicillin was a bactericidal enzyme led Chain to consider that it would be similar to lysozyme. Money was short at the time; the office had an overdraft of £500 (equivalent to £31,000 in 2025) and Florey had to forbid the purchase of any further equipment. Chain and Florey decided to create a large research project on antibacterial substances produced by micro-organisms that could attract long-term funding. Three sources were initially chosen for investigation: Bacillus subtilis, Trueperella pyogenes and penicillin mould. Florey later said:
=== Chemical === Darmstadtium is the eighth member of the 6d series of transition metals, and should be much like the platinum group metals. Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue platinum, thus implying that darmstadtium's basic properties will resemble those of the other group 10 elements, nickel, palladium, and platinum. Prediction of the probable chemical properties of darmstadtium has not received much attention recently. Darmstadtium should be a very noble metal. The predicted standard reduction potential for the Ds2+/Ds couple is 1.7 V. Based on the most stable oxidation states of the lighter group 10 elements, the most stable oxidation states of darmstadtium are predicted to be the +6, +4, and +2 states; however, the neutral state is predicted to be the most stable in aqueous solutions. In comparison, only platinum is known to show the maximum oxidation state in the group, +6, while the most stable state is +2 for both nickel and palladium. It is further expected that the maximum oxidation states of elements from bohrium (element 107) to darmstadtium (element 110) may be stable in the gas phase but not in aqueous solution. Darmstadtium hexafluoride (DsF6) is predicted to have very similar properties to its lighter homologue platinum hexafluoride (PtF6), having very similar electronic structures and ionization potentials. It is also expected to have the same octahedral molecular geometry as PtF6.
Sources: en.wikipedia.org
Zopiclone, sold under the brand name Imovane among others, is a benzodiazepine-like drug (Z-drug) used as a pharmaceutical treatment for insomnia. While molecularly distinct from benzodiazepine drugs, zopiclone's mechanism of action is similar: it increases the transmission of the neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system, via positive allosteric modulation at GABAA neurons. Zopiclone is considered a sedative and CNS depressant. Zopiclone and other benzodiazepine-like drugs like zaleplon and zolpidem are addictive. Within days to weeks, the body can become accustomed to the effects of zopiclone. The risk of developing tolerance with benzodiazepine-like drugs is comparable to benzodiazepines. When the dose is then reduced or the drug is abruptly stopped, withdrawal symptoms similar to those of benzodiazepine withdrawal may result. Benzodiazepine-like drugs decrease sleep latency by 10 to 20 minutes. However, no benzodiazepine-like drug has shown clinically significant increase in total sleep time. Zopiclone is recommended only to be taken at the lowest effective dose, with a duration of 2–3 weeks, for short-term insomnia. Use of zopiclone more than 4 weeks is not recommended. It is dangerous to take with benzodiazepines, sedatives, alcohol or other drugs affecting the central nervous system. In the United States, zopiclone is not commercially available, although its active stereoisomer, eszopiclone, is.
=== Activity === This enzyme participates in 8 metabolic pathways: alanine and aspartate metabolism, methionine metabolism, valine, leucine and isoleucine degradation, tyrosine metabolism, phenylalanine metabolism, tryptophan metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and alkaloid biosynthesis. It employs one cofactor, flavin adenine dinucleotide (FAD). The enzyme binds to FAD in the first step of the catalytic process, thereby reducing FAD to FADH2. The FAD is regenerated from FADH2 by oxidation as a result of O2 being reduced to H2O2. The mechanism proceeds via oxidative deamination of the L-amino acid, which affords an imino acid intermediate. Following hydrolysis of the intermediate, the enzyme successfully affords the 2-oxo acid, as shown in Scheme 1.
===== North America ===== The U.S. National Academy of Medicine (NAM), on behalf of both the U.S. and Canada, sets Dietary Reference Intakes, including Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs), or Adequate Intakes (AIs) for when there is not sufficient information to set EARs and RDAs. For both males and females under 9 years of age, the AIs for potassium are: 400 mg of potassium for 0 to 6-month-old infants, 860 mg of potassium for 7 to 12-month-old infants, 2,000 mg of potassium for 1 to 3-year-old children, and 2,300 mg of potassium for 4 to 8-year-old children. For males 9 years of age and older, the AIs for potassium are: 2,500 mg of potassium for 9 to 13-year-old males, 3,000 mg of potassium for 14 to 18-year-old males, and 3,400 mg for males that are 19 years of age and older. For females 9 years of age and older, the AIs for potassium are: 2,300 mg of potassium for 9 to 18-year-old females, and 2,600 mg of potassium for females that are 19 years of age and older. For pregnant and lactating females, the AIs for potassium are: 2,600 mg of potassium for 14 to 18-year-old pregnant females, 2,900 mg for pregnant females that are 19 years of age and older; furthermore, 2,500 mg of potassium for 14 to 18-year-old lactating females, and 2,800 mg for lactating females that are 19 years of age and older. As for safety, the NAM also sets tolerable upper intake levels (ULs) for vitamins and minerals, but for potassium the evidence was insufficient, so no UL was established. As of 2004, most Americans adults consume less than 3,000 mg.
Although the mechanism of action for β-lactam antibiotics is not completely known they are believed to exert their mechanism of action by mimicking the structure of the transition state of the chemical reaction when the transpeptidase is bound to the D-alanyl-D-alanine sequence. These proteins are often referred to as penicillin binding proteins (PBP). Opening of the β-lactam ring by a serine residue in the enzyme binding site leads to covalent binding of the antibiotic molecule with the active site of the enzyme. The result is an inactive irreversibly bound enzyme-complex which is incapable of further cell wall synthesis and the cell will die from osmotic-lysis.
Sources: en.wikipedia.org
== B == B3/B4 tRNA-binding domain - B5 protein domain - BAC - back mutation - bacteria - bacterial artificial chromosome - bacteriophage - bacteriophage lambda - bacteriophage scaffolding proteins - band shift assay - base - base pair - benzoyl-CoA 2,3-dioxygenase - benzyl benzoate/disulfiram - benzyl-2-methyl-hydroxybutyrate dehydrogenase - beta-carotene 3-hydroxylase - beta-cyclopiazonate dehydrogenase - beta-glucan-transporting ATPase - beta2-adaptin C-terminal domain - binding site - biological organisation - biological process - Biomolecular gradient - Biomolecule Stretching Database - biotin - birth defect - blotting - blunt end - bone marrow transplantation - box - BP - BRCA1 - BRCA2 - Brix (database) - BSD domain - BURP domain -
The sequence in which the subshells are filled is given in most cases by the Aufbau principle, also known as the Madelung or Klechkovsky rule (after Erwin Madelung and Vsevolod Klechkovsky respectively). This rule was first observed empirically by Madelung, and Klechkovsky and later authors gave it theoretical justification. The shells overlap in energies, and the Madelung rule specifies the sequence of filling according to:
==== Financial status ==== Poverty and an individual's financial status play a critical role in the challenges of mental health. Low-income individuals and families often experience physical barriers to accessing mental health treatments, significantly increasing the chances of mental health struggles. Job insecurity, shame surrounding financial resources, and inability to seek professional help stimulate external and internal stigma. Societal norms may lead to an expectation that if financially unsuccessful, unemployment results in personal failure and negative stereotypes. Unemployed individuals may be perceived as irresponsible, unmotivated, and lazy. Psychological stress surrounding financial stability causes internalized discrimination and societal judgment. A study emphasized that using interventions and professional treatments will reduce psychological stress, normalize needing accessible health care, and decrease stigma around mental health regardless of economic background.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.