Reversed-phase HPLC 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.
Last reviewed on 2026-06-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
| 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 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。
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
It is possible that it may be related to Cirroteuthis, and in that case the two posterior stumps, looking like arms, may be the remains of the lateral fins, for they seem too far back for the arms, unless pulled out of position. On the other hand, they seem to be too far forward for fins. So that they are probably arms twisted out of their true position. However, having examined samples of the mass sent to him by Webb, Verrill concluded that "the creature cannot be an Octopus, but is of cetacean nature." He suggested that "the whole mass represents the upper part of the head of [a sperm whale], detached from the skull and jaw." Webb decided the carcass should be moved further inland so that it would not be lost to the sea forever. With the help of "six horses and strong tackle", it was moved several miles closer to St. Augustine, "to the terminus of a railroad," where it was protected from the tide and drifting sand. Its final resting place was South Beach, Anastasia Island, near the hotel of Dr. George Grant. The St. Augustine carcass became somewhat of a tourist attraction and was visited by large numbers of people. It is unknown what happened to the carcass afterwards. Photographs of the St. Augustine carcass were for a long time thought to be lost, and drawings remained the only pictorial evidence of the event. They were finally rediscovered in 1993 by Marjorie Blakoner of California, who recognised them in an old album. Van Lockwood, one of the original photographers of the St. Augustine carcass, kept an album of photos he had taken between 1885 and 1899.
Cry Freedom is a 1987 epic biographical drama film directed and produced by Richard Attenborough, set in apartheid-era South Africa in 1977. The screenplay was written by John Briley based on a pair of books by journalist Donald Woods. The film centres on the real-life events involving South African activist Steve Biko and his friend Woods, who initially finds him too radical, and attempts to understand his way of life. Denzel Washington stars as Biko, while Kevin Kline portrays Woods. Penelope Wilton co-stars as Woods's wife Wendy. Cry Freedom delves into the ideas of racism, segregation, disenfranchisement, socioeconomic inequality, political corruption, and the repercussions of violence. A joint collective effort to commit to the film's production was made by Universal Pictures and Marble Arch Productions and the film was primarily shot on location in Zimbabwe due to not being allowed to film in South Africa at the time of production. It was commercially distributed by Universal Pictures, opening in the United States on 6 November 1987. South African authorities unexpectedly allowed the film to be screened in cinemas without cuts or restrictions, despite the publication of Biko's writings being banned at the time of its release. The film was generally met with favourable reviews and earned theatrical rentals of $15 million worldwide. The film was nominated for multiple awards, including Academy Award nominations for Best Supporting Actor (for Washington), Best Original Score, and Best Original Song.
This means they can metabolize synthesis gas, a gas mixture of CO, H2 and CO2 that can be made by gasification of residual intractable biowastes such as lignocellulose. Some bacteria are diazotrophic, i.e. they can fix N2 from the air and are thus independent of chemical N-fertilizer, whose production, utilization and degradation causes tremendous harm to the environment, deteriorates public health, and fosters climate change. Many bacteria can utilize H2 for energy supply, using enzymes called hydrogenases. Whereas hydrogenases are normally highly O2-sensitive, some bacteria are capable of performing O2-dependent respiration of H2. This feature allows autotrophic bacteria to grow on CO2 without light at a fast growth rate. Since H2 can be made efficiently by water electrolysis, in a manner of speaking, those bacteria can be "powered by electricity". Microbial biomass production is independent of seasonal and climatic variations, and can easily be shielded from extreme weather events that are expected to cause crop failures with the ongoing climate-change. Light-independent microorganisms such as yeasts can continue to grow at night. Cultivation of microorganisms generally has a much lower water footprint than agricultural food production. Whereas the global average blue-green water footprint (irrigation, surface, ground and rain water) of crops reaches about 1800 liters per kg crop due to evaporation, transpiration, drainage and runoff, closed bioreactors producing SCP exhibits none of these causes.
Sources: en.wikipedia.org
== Microbiology == The environment of the gingival sulcus is unlike any other location within the mouth. The ecosystem of the gingival sulcus is more anaerobic, and the site is filled with Gingival Crevicular Fluid (GCF). In the presence of periodontal disease, the gingival sulcus becomes a periodontal pocket and the oxidation reduction potential will decrease to low levels as the site is very anaerobic. At the same time, the gingival crevicular fluid would have increased by 147% when gingivitis is present and would have increased by up to 30-fold where periodontitis is present. While gingival crevicular fluid provides for the cellular defence and humoral factors to combat against the microbial insult, the gingival crevicular fluid also deliver novel substrates, in the form of proteins and glycoproteins, for bacterial metabolism. These include haeme containing molecules and iron, such as haemoglobin and transferrin. Dissimilarly to dental caries, many bacteria associated to periodontal disease cannot metabolise carbohydrates for energy (they are asaccharolytic) and are proteolytic too. One effect of proteolysis is that the pH of the gingival pocket with periodontal disease will increase and becomes slightly alkaline at around a pH level of 7.4 – 7.8 as compared to relatively neutral pH values, around a pH level of 6.9, when the gingival is healthy. In alkaline growth conditions, the enzyme activity and growth activity of periodontal pathogens, like Porphyromonas gingivalis.
== Food and Drug Administration == The FDA has minimal control when regulating dietary supplements like pre-workout. Product manufacturers are responsible to verify that dietary supplements are safe for consumption. Financial limitations prevent the FDA from testing dietary supplements before they enter the marketplace. Once a supplement is available for sale, the FDA is responsible to document and monitor manufacturer reports of adverse effects. Manufacturers are obligated to report documented adverse effects to the FDA. The FDA recommends speaking with a healthcare professional before using dietary supplements. Ingredients in pre-workout can have negative side effects or contraindications with other medications. Taking dietary supplements may have life-threatening consequences if taken with pre-existing health conditions. Federal laws state that a supplement does not have to be declared safe by FDA standards when labeled. Most supplement businesses hire third-party companies to identify the contents of their supplement to ensure it enhances athletic performance. This also aids in assuring that a product's labeled ingredients are free from illegal substances.
A number of cancer immunotherapy agents that target the PD-1 receptor have been developed. One such anti-PD-1 antibody drug, nivolumab, (Opdivo - Bristol Myers Squibb), produced complete or partial responses in non-small-cell lung cancer, melanoma, and renal-cell cancer, in a clinical trial with a total of 296 patients. Colon and pancreatic cancer did not have a response. Nivolumab (Opdivo, Bristol-Myers Squibb) was approved in Japan in July 2014 and by the US FDA in December 2014 to treat metastatic melanoma. Pembrolizumab (Keytruda, MK-3475, Merck), which also targets PD-1 receptors, was approved by the FDA in Sept 2014 to treat metastatic melanoma. Pembrolizumab has been made accessible to advanced melanoma patients in the UK via UK Early Access to Medicines Scheme (EAMS) in March 2015. It is being used in clinical trials in the US for lung cancer, lymphoma, and mesothelioma. It has had measured success, with little side effects. It is up to the manufacturer of the drug to submit application to the FDA for approval for use in these diseases. On October 2, 2015, Pembrolizumab was approved by FDA for advanced (metastatic) non-small cell lung cancer (NSCLC) patients whose disease has progressed after other treatments. Toripalimab is a humanized IgG4 monoclonal antibody against PD-1 which was approved in China in 2018 and in the United States in 2023. Drugs in early stage development targeting PD-1 receptors (checkpoint inhibitors) include pidilizumab (CT-011, Cure Tech) and BMS-936559 (Bristol Myers Squibb).
Sources: en.wikipedia.org
Southeast of the city centre stands San Salvario district, which extends from Corso Vittorio Emanuele II to Corso Bramante and is delimited by the Turin-Genoa railway on the west side and by the River Po on the east side. Home to an increasing immigrants' community, the district is an example of integration among different cultures; it also features an incremented nightlife after the opening of several low-cost bars and restaurants. San Salvario is crossed by two main roads, Via Nizza and Via Madama Cristina, and just as the city centre it is characterised by the grid plan typical of Turin's old neighbourhoods. The hub of the district is Piazza Madama Cristina which hosts a big open market, while several commercial activities flourish around it. The celebrated Parco del Valentino is situated in the east side of San Salvario and, albeit not in downtown, it represents a type of central park of Turin. Thanks to the vicinity to the city centre, the park is very popular among the local people, during the day but also at night, because of the several bars and nightclubs placed here. From the terraces of Parco del Valentino, many sights of the hills on the other side of the river can be appreciated. In the centre of the park stands the Castello del Valentino, built in the 17th century. This castle has a horseshoe shape, with four rectangular towers, one at each angle, and a wide inner court with a marble pavement. The ceilings of the false upper floors are in transalpino (i.e. French) style. The façade sports the huge coat of arms of the House of Savoy.
=== 30 December === The Ukrainian army claimed to have shot down 16 drones launched by Russian forces at Kyiv and other cities. The Mayor of Kyiv, Vitali Klitschko, stated that two were shot down outside Kyiv while five were shot down "over" Kyiv. President Putin and Chinese President Xi Jinping held talks via video link in which the latter reassured the former that he would maintain an "objective and fair stance" regarding the situation, according to CCTV.
== Dangers == Scarification produces harm and trauma to the skin. Infection is common when tools are not sterilised properly. Scarification has been linked to the spread of HIV/AIDS and Hepatitis C when tools are shared between people. Body modification artists may have less experience with scarification, perhaps due to lower demand. When not desired, keloid scars may be an additional complication, although there are emerging treatment strategies for them.
== History == The Dutch introduced cold brew coffee to Japan, where it has been a traditional method of coffee brewing for centuries. Slow-drip Cold brew refers to a process in which water is dripped through coffee grounds at room temperature over the course of many hours. It has been called "Kyoto-style", or in East Asia "Dutch coffee".
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.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.