Everything below concerns mass spectrometry. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-11-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
| 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 |
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Homology modeling is based on the reasonable assumption that two homologous proteins will share very similar structures. Because a protein's fold is more evolutionarily conserved than its amino acid sequence, a target sequence can be modeled with reasonable accuracy on a very distantly related template, provided that the relationship between target and template can be discerned through sequence alignment. It has been suggested that the primary bottleneck in comparative modelling arises from difficulties in alignment rather than from errors in structure prediction given a known-good alignment. Unsurprisingly, homology modelling is most accurate when the target and template have similar sequences. Protein threading scans the amino acid sequence of an unknown structure against a database of solved structures. In each case, a scoring function is used to assess the compatibility of the sequence to the structure, thus yielding possible three-dimensional models. This type of method is also known as 3D-1D fold recognition due to its compatibility analysis between three-dimensional structures and linear protein sequences. This method has also given rise to methods performing an inverse folding search by evaluating the compatibility of a given structure with a large database of sequences, thus predicting which sequences have the potential to produce a given fold.
Normally, Hagen–Poiseuille flow implies not just the relation for the pressure drop, above, but also the full solution for the laminar flow profile, which is parabolic. However, the result for the pressure drop can be extended to turbulent flow by inferring an effective turbulent viscosity in the case of turbulent flow, even though the flow profile in turbulent flow is strictly speaking not actually parabolic. In both cases, laminar or turbulent, the pressure drop is related to the stress at the wall, which determines the so-called friction factor. The wall stress can be determined phenomenologically by the Darcy–Weisbach equation in the field of hydraulics, given a relationship for the friction factor in terms of the Reynolds number. In the case of laminar flow, for a circular cross section:
It was not until the beginning of the 19th century that it became clear that reptiles and amphibians are, in fact, quite different animals, and P.A. Latreille erected the class Batracia (1825) for the latter, dividing the tetrapods into the four familiar classes of reptiles, amphibians, birds, and mammals. The British anatomist T.H. Huxley made Latreille's definition popular and, together with Richard Owen, expanded Reptilia to include the various fossil "antediluvian monsters", including dinosaurs and the mammal-like (synapsid) Dicynodon he helped describe. This was not the only possible classification scheme: In the Hunterian lectures delivered at the Royal College of Surgeons in 1863, Huxley grouped the vertebrates into mammals, sauroids, and ichthyoids (the latter containing the fishes and amphibians). He subsequently proposed the names of Sauropsida and Ichthyopsida for the latter two groups. In 1866, Haeckel demonstrated that vertebrates could be divided based on their reproductive strategies, and that reptiles, birds, and mammals were united by the amniotic egg. The terms Sauropsida ("lizard faces") and Theropsida ("beast faces") were used again in 1916 by E.S. Goodrich to distinguish between lizards, birds, and their relatives on the one hand (Sauropsida) and mammals and their extinct relatives (Theropsida) on the other. Goodrich supported this division by the nature of the hearts and blood vessels in each group, and other features, such as the structure of the forebrain.
Beverly Gail Allitt (born 4 October 1968) is an English serial killer who was convicted of murdering three infants and an 11-year-old boy, attempting to murder three others, and causing grievous bodily harm to six more at Grantham and Kesteven Hospital, Lincolnshire, between February and April 1991. She committed the murders as a state enrolled nurse on the hospital's children's ward. Allitt administered large doses of insulin to at least two of her victims and a large air bubble was found in the body of another, but police were initially unable to establish how all of the attacks were carried out. In May 1993, Allitt received 13 life sentences at Nottingham Crown Court. The sentencing judge, Mr Justice David Latham, told Allitt that she was "a serious danger" to others and was unlikely ever to be considered safe enough to be released. Allitt is currently detained at Rampton Secure Hospital in Nottinghamshire. She became eligible for release on parole after her minimum tariff of 30 years' imprisonment expired in November 2021.
=== 2010–2012: Early career === Melksham was recruited by the Essendon Football Club with their first selection and tenth overall in the 2009 national draft. The Age journalist, Will Brodie, predicted he would debut and play in the midfield early in the season and he made his debut in the twenty point win against Carlton at the Melbourne Cricket Ground in round three. He played the next two matches before he was omitted for the round six match against Hawthorn at the Melbourne Cricket Ground; he returned the next week for the three-point loss against Port Adelaide at Etihad Stadium where he kicked his first AFL goal. He was rewarded with the round eight nomination in the AFL Rising Star after he recorded fourteen possessions, three clearances, three tackles and a goal in the twelve point win against St Kilda at Etihad Stadium. He missed the round ten match against the Western Bulldogs after he sprained his ankle during the thirty-five-point win against Richmond the week before, he returned the next week for the nine-point loss against Sydney at the Sydney Cricket Ground. He played the next four out of five matches, missing the round fifteen match against Melbourne due to being rested, before he was dropped for the round seventeen match against North Melbourne at Etihad Stadium.
Sources: en.wikipedia.org
More recently, the initiative focused on improving security around Mexico's southern border and countering the production and trafficking of heroin and fentanyl. Until March 2017, more than $1.6bn has been invested in the Merida initiative, of which almost $900,000 was spent on protective equipment necessary for the secured demolishing of narcotic labs. In Mexico, the DEA combats operations of DTOs by conducting bilateral investigations with foreign counterparts, providing investigative assistance and leads to DEA domestic offices and other agencies, providing training and technical equipment to 'host nation participants to initiate and carry out complex criminal investigations, providing assistance in developing drug control laws and regulations, and providing training and material support to foreign law enforcement counterparts'.
A sector instrument is a general term for a class of mass spectrometer that uses a static electric (E) or magnetic (B) sector or some combination of the two (separately in space) as a mass analyzer. Popular combinations of these sectors have been the EB, BE (of so-called reverse geometry), three-sector BEB and four-sector EBEB (electric-magnetic-electric-magnetic) instruments. Most modern sector instruments are double-focusing instruments (first developed by Francis William Aston, Arthur Jeffrey Dempster, Kenneth Bainbridge and Josef Mattauch in 1936) in that they focus the ion beams both in direction and velocity.
Doxylamine is an antihistamine medication used to treat insomnia and allergies, and—in combination with pyridoxine (vitamin B6)—to treat morning sickness in pregnant women. It is available over-the-counter and is sold under such brand names as Unisom, among others; and it is used in nighttime cold medicines (e.g., NyQuil) and pain medications containing paracetamol (acetaminophen) or codeine to help with sleep. The medication is delivered chemically by the salt doxylamine succinate and is taken by mouth. Doxylamine and other first-generation antihistamines are the most widely used sleep medications in the world. Typical side effects of doxylamine include dizziness, drowsiness, grogginess, and dry mouth, among others. As an antihistamine, doxylamine is an inverse agonist of the histamine H1 receptor. As a first-generation antihistamine, it typically crosses the blood–brain barrier into the brain, thereby producing a suite of sedative and hypnotic effects that are mediated by the central nervous system. Doxylamine is also a potent anticholinergic, meaning that it causes delirium at high doses (i.e., at much higher doses than recommended). Specifically, it is an antagonist of the muscarinic acetylcholine receptors M1 through M5. These sedative and deliriant effects have in some cases led to the drug being used recreationally. Doxylamine was first described in 1948 or 1949.
2 December – Neville Callaghan, 77, racehorse trainer. 5 December – Rosemary Smith, 86, rally driver. 7 December – Thomas Kilroy, 89, playwright and novelist. 10 December Jonathan Irwin, 82, blood stock agent, auctioneer, stud owner, publisher and founder of the Jack and Jill Foundation. Syd Millar, 89, rugby union player (Ballymena, national team), coach (British & Irish Lions) and International Rugby Board chairman (2003–2007). Born in Northern Ireland. Bill McCarthy, 87, hurler (St Brendan's, Ardfert, Kerry junior team, Munster). 11 December – Frank Twomey, 68, children's television entertainer and comedian (Bosco, Bull Island). 16 December – Joseph Finnegan, 81, judge. 17 December – Maureen Flavin Sweeney, 100, postmistress and formerly a weather forecaster notable for advising on the D-Day landings. 20 December – Johnny Flaherty, 76, hurler (Kinnitty, Offaly senior team, Leinster). 21 December – Martin Feeley, 73, Olympic rower (1976) and surgeon. 27 December – Éamonn Draper, 83, actor and director. 28 December – Patrick Walsh, 92, Roman Catholic prelate, bishop of Down and Connor (1991–2008). 30 December – Paddy Murphy, 89, Gaelic footballer (Dromtarriffe, Duhallow, Cork senior team.
=== Top-down methods === Top-down methods adopt some 'force' (e. g. mechanical force, laser) to break bulk materials into nanoparticles. A popular method involves mechanical break apart bulk materials into nanomaterials is 'ball milling'. Besides that, nanoparticles can also be made by laser ablation which apply short pulse lasers (e. g. femtosecond laser) to ablate a target (solid).
Sources: en.wikipedia.org
=== Genetics === From 2005 to 2007, Curis and Procter & Gamble collaborated on developing a topical hedgehog agonist for hair loss; the agent did not meet safety standards, and the program was terminated. In 2008, researchers at the University of Bonn announced they have found the genetic basis of two distinct forms of inherited hair loss. They found the gene P2RY5 causes a rare, inherited form of hair loss called hypotrichosis simplex. It is the first receptor in humans known to play a role in hair growth. Researchers found that disruption of the gene SOX21 in mice caused cyclical hair loss. Research has suggested SOX21 as a master regulator of hair shaft cuticle differentiation, with its disruption causing cyclical alopecia in mice models. Deletion of SOX21 dramatically affects hair lipids.
In dental anatomy, the gingival sulcus is an area of potential space between a tooth and the surrounding gingival tissue and is lined by sulcular epithelium. The depth of the sulcus (Latin for groove) is bounded by two entities: apically by the gingival fibers of the connective tissue attachment and coronally by the free gingival margin. A healthy sulcular depth is three millimeters or less, which is readily self-cleansable with a properly used toothbrush or the supplemental use of other oral hygiene aids.
== Life and work == Lundsgaard was born in Copenhagen where his father was a physician who came from the Gundelach family of lawyers and civil servants His father received a gold medal for his work on prostatic hypertrophy from the University of Copenhagen. At school he played guitar as a hobby. In 1917 he completed school and entered medical studies. He completed studies in 1923 and worked at the institute of medical physiology under Valdemar Henriques. He received a doctorate in 1929. His major finding was on muscle contraction when glycolysis was blocked by mono-iodoacetate. He found that energy was drawn from the phosphate bond energy and he published the findings in 1930. Until then it was believed that glycolysis was the main source of energy. Creatine phosphate was independently identified in muscle by the Eggletons and by Cyrus H. Fiske and Subbarow in 1926. From 1934 he began to work on phlorizin and its metabolic effects. This was continued with insulin in studies of perfused livers. In 1938 he examined the metabolism of alcohol and its conversion to acetic acid by the liver. He received the Thunberg medal in 1960 and the Anders Jahre prize for 1964. Herman Kalckar was among his students. He retired in 1967 and died from renal cancer the next year.
Turquoise may also pseudomorphously replace feldspar, apatite, other minerals, or even fossils. Odontolite is fossil bone or ivory that has historically been thought to have been altered by turquoise or similar phosphate minerals such as the iron phosphate vivianite. Intergrowth with other secondary copper minerals such as chrysocolla is also common. Turquoise is distinguished from chrysocolla, the only common mineral with similar properties, by its greater hardness. Turquoise forms a complete solid solution series with chalcosiderite, CuFe6(PO4)4(OH)8·4H2O, in which ferric iron replaces aluminium.
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.
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。