This is a working overview of mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-26 and is reviewed periodically as new material appears.
Claims about enhanced focus, memory, or mood in healthy people rest mostly on anecdotal reports and community discussion rather than on controlled data. It remains unclear whether any cognitive benefit observed in patients recovering from brain injury would extend to uninjured users. Dose-response relationships, long-term safety, and interactions with other drugs are not well characterized in the peer-reviewed literature. Questions about optimal route of administration and treatment duration likewise remain open.
Semax binds to melanocortin receptors and is thought to influence neuronal survival and plasticity rather than to act through the adrenal axis. Laboratory work has shown increased expression of brain-derived neurotrophic factor and nerve growth factor in treated tissue. Changes in c-Fos, a marker of neuronal activation, have also been reported. Because the peptide is rapidly degraded by peptidases, its effects are generally attributed to downstream signaling cascades rather than to sustained receptor occupancy.
Published studies are dominated by animal models of stroke, ischemia, and cognitive impairment, with a smaller number of human trials conducted in Russia. Many of the human reports are small, single-center, and published in Russian-language journals, which limits independent scrutiny. Outcome measures vary between studies and often rely on clinician-rated scales rather than objective biomarkers. Systematic reviews have noted the methodological weaknesses and called for larger, preregistered trials before firm conclusions can be drawn.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White lyophilized powder | Typical for synthetic peptides |
| Solubility | Freely soluble in water | Also soluble in saline |
| Storage temperature | -20 C or below | Protect from repeated freeze-thaw |
| Analytical method | Reverse-phase HPLC | Confirms purity and identity |
| Common synonym | ACTH(4-10) analog | Reflects structural origin |
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.
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
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.
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.
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
Chick-fil-A, Inc. ( CHIK-fil-AY, a play on the American English pronunciation of "filet") is an American fast food restaurant chain and the largest chain specializing in chicken sandwiches. Headquartered in College Park, Georgia, Chick-fil-A operates restaurants across 48 states, as well as in the District of Columbia and Puerto Rico. The company also has operations in Canada, the United Kingdom, and Singapore, and previously had restaurants in South Africa. The restaurant has a breakfast, a lunch, and a dinner menu. The chain also provides catering services. Chick-fil-A calls its specialty the "original chicken sandwich". It is a piece of deep-fried breaded boneless chicken breast served on a toasted bun with two slices of dill pickle, or with lettuce, tomato, and cheese. Many of the company's values are influenced by the Christian religious beliefs of its late founder, S. Truett Cathy (1921–2014), a devout Southern Baptist. Reflecting a commitment to Sunday Sabbatarianism, all Chick-fil-A restaurants are closed for business on Sundays, and Christmas Day, as well as Thanksgiving for US and Canadian locations. The company's conservative opposition to same-sex marriage has caused controversy; the company began to loosen its stance on this issue from 2019. Even among numerous controversies and boycott attempts, the 2022 American Customer Satisfaction Index found that Chick-fil-A remained the country's favorite fast food chain for the eighth consecutive year, and it has the highest per store sales of any fast food chain in the nation.
Germany was particularly important in the early modernist movement: it is the home of Werkbund initiated by Hermann Muthesius (New Objectivity), and of the Bauhaus movement founded by Walter Gropius. Ludwig Mies van der Rohe became one of the world's most renowned architects in the second half of the 20th century; he conceived of the glass façade skyscraper. Renowned contemporary German architects and offices include Pritzker Prize winners Gottfried Böhm and Frei Otto.
Adolescent medicine Adult congenital heart disease Advanced heart failure and transplant cardiology Cardiovascular disease, dealing with disorders of the heart and blood vessels* Clinical cardiac electrophysiology Critical care medicine, is dealing with life-threatening conditions requiring intensive monitoring and treatment. Endocrinology, diabetes & metabolism, dealing with disorders of the endocrine system and its specific secretions called hormones Gastroenterology, concerned with the field of digestive diseases Geriatric medicine Hematology, concerned with blood, the blood-forming organs and its disorders. Hospice & palliative medicine Infectious disease, concerned with disease caused by a biological agent such as by a virus, bacterium or parasite Interventional cardiology Medical oncology, dealing with the chemotherapeutic (chemical) and/or immunotherapeutic (immunological) treatment of cancer Nephrology, dealing with the study of the function and diseases of the kidney Neurocritical care Pulmonary disease, dealing with diseases of the lungs and the respiratory tract Rheumatology, devoted to the diagnosis and therapy of rheumatic diseases Sleep medicine Sports medicine Transplant hepatology
Pyrolysis is the basis of several methods for producing fuel from biomass, i.e. lignocellulosic biomass. Crops studied as biomass feedstock for pyrolysis include native North American prairie grasses such as switchgrass and bred versions of other grasses such as Miscantheus giganteus. Other sources of organic matter as feedstock for pyrolysis include greenwaste, sawdust, waste wood, leaves, vegetables, nut shells, straw, cotton trash, rice hulls, and orange peels. Animal waste including poultry litter, dairy manure, and potentially other manures are also under evaluation. Some industrial byproducts are also suitable feedstock including paper sludge, distillers grain, and sewage sludge. In the biomass components, the pyrolysis of hemicellulose happens between 210 and 310 °C. The pyrolysis of cellulose starts from 300 to 315 °C and ends at 360–380 °C, with a peak at 342–354 °C. Lignin starts to decompose at about 200 °C and continues until 1000 °C. Synthetic diesel fuel by pyrolysis of organic materials is not yet economically competitive. Higher efficiency is sometimes achieved by flash pyrolysis, in which finely divided feedstock is quickly heated to between 350 and 500 °C (660 and 930 °F) for less than two seconds. Syngas is usually produced by pyrolysis. The low quality of oils produced through pyrolysis can be improved by physical and chemical processes, which might drive up production costs, but may make sense economically as circumstances change.
Sources: en.wikipedia.org
Solution concentration Drying gas flow Inlet temperature Spraying gas flow Feed rate From the following input parameters comes a series of pathways a particle can take towards its yielded shape and size. Certain parameters like spraying gas flow, feed rate, and the solution concentration heavily influence the yielded particle size, whereas the inlet temperature plays a significant role into the shape of the particle at the end. Particle size has a great correlation with the original size of the solution droplet from the atomizer, so the greatest way to control particle size can be done by heavily saturating the solution and making the initial droplet larger or smaller. Once the initial droplet enters the drying chamber, the droplet can continue to crust formation, or no particle will be formed. From the crust formation, the temperature of the drying process and duration of the particle in the drying process can lead the particle toward a dry shell or a deformed particle. The dry shell can proceed into a solid particle or a shattered particle. The crust formation can also forgo the dry shell or deformed particle if the drying conditions are not correct and undergo an internal bubble nucleation with another series of pathways.
== Namibian independence == The initial terms of the Geneva Protocol and Security Council Resolution 435 provided the foundation from which a political settlement in South West Africa could proceed: holding of elections for a constitutional assembly, confinement of both PLAN and the SADF to their respective bases, the subsequent phased withdrawal of all but 1,500 SADF troops, demobilisation of all paramilitary forces that belonged to neither the SADF nor to the police, and the return of refugees via designated entry points to participate in elections. Responsibility for implementing these terms rested with UNTAG, which would assist in the SADF withdrawal, monitor the borders, and supervise the demobilisation of paramilitary units.
nucleotidase Any of a class of phosphoric monoester hydrolase enzymes which catalyze the hydrolysis of a nucleotide into a nucleoside and orthophosphate. Such enzymes may or may not distinguish ribonucleotides from deoxyribonucleotides, i.e. their function may not be sugar-specific.
Sources: en.wikipedia.org
where j is the James–Martin pressure drop correction, m is the sample mass, F is the carrier gas flow rate at standard temperature and pressure, tR is the gross retention time for the injected probe, to is the retention time for a non-interaction probe (i.e. dead-time), and T is the absolute temperature.
The symbol of the registering organization (in the diagram above this is the US Government); the last two digits of the animal's year of birth (estimated from teeth), stacked vertically; the registration number, a unique sequence of angles arranged horizontally. The first two numerals of the registration number indicate the BLM facility at which the horse was processed (this is not always in the same state where the horse was captured). The next four numerals compose the horse's tag number and are randomly assigned during processing. Finally, a horizontal line beneath the registration number. This line acts as an orientation mark for the angle numerals. This is done in case the horse's skin shifts as it grows, if it loses weight or becomes cresty (an overabundance of fat deposition at the crest of the neck). Such distortions can appear to change one numeral into another. Angles are always interpreted with reference to the horizontal line. If a mustang has been offered for adoption three times and has not settled at any of its new locations the horse is referred to as "Sale Authority." This means that BLM is legally authorized to sell the horse to anyone willing to buy it. The BLM is prohibited by law from controlling wild horse populations through culling, but Sale Authority sometimes amounts to the same thing as intractable horses are often sold to slaughterhouses or their agents. Sale Authority is indicated with a large ᑌ shape after the registration number. If a horse is neither adopted nor deemed Sale Authority it is often housed at a long-term BLM pasture.
He sponsored Proposition B to require Muni and other city departments to develop detailed customer service plans. The measure passed with 56.6% of the vote. Newsom sponsored a ballot measure from Rescue Muni; a version of the measure was approved by voters in November 1999. Newsom also supported allowing restaurants to serve alcohol at their outdoor tables, banning tobacco advertisements visible from the streets, stiffer penalties for landlords who run afoul of rent-control laws, and a resolution, which was defeated, to commend Colin Powell for raising money for youth programs. Newsom's support for business interests at times strained his relationship with labor leaders. During Newsom's time as supervisor, he supported housing projects through public-private partnerships to increase homeownership and affordable housing in San Francisco. He supported HOPE, a failed local-ballot measure that would have allowed an increased condo-conversion rate if a certain percentage of tenants within a building were buying their units. As a candidate for mayor, he supported building 10,000 new housing units to create 15,000 new construction jobs. Newsom's signature achievement as a supervisor was a voter initiative called Care Not Cash (Measure N), which offered care, supportive housing, drug treatment, and help from behavioral health specialists for the homeless in lieu of direct cash aid from the state's general assistance program. Many homeless rights advocates protested against the initiative.
==== Apoptosis ==== Caspases are an important group of proteases involved in apoptosis or programmed cell death. The precursors of caspase, procaspase, may be activated by proteolysis through its association with a protein complex that forms apoptosome, or by granzyme B, or via the death receptor pathways.
Sources: en.wikipedia.org
It is associated with the melanocortin receptor family, particularly subtypes found in the central nervous system. This interaction is separate from the adrenal pathway activated by full-length ACTH.
Peptidases degrade the compound within minutes in circulation. This short half-life is one reason nasal delivery is used, placing the substance close to the olfactory and trigeminal pathways.
No large multicenter trials have been published in English-language journals. The existing human evidence consists mainly of smaller studies conducted in Russia, which limits generalization.
Semax is based on the ACTH(4-10) fragment, a seven-amino-acid segment of adrenocorticotropic hormone. The synthetic peptide retains the core sequence while removing regions associated with endocrine activity. This modification is intended to isolate effects on the nervous system.