The short version of mass spectrometry fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-06. Anything still debated is marked as such rather than presented as settled.
Semax 是一种人工合成的七肽，氨基酸序列为 Met-Glu-His-Phe-Pro-Gly-Pro，单字母缩写记作 MEHFPGP。它被归类为促肾上腺皮质激素片段 ACTH(4-10) 的结构类似物，但并不天然存在于生物体内。母体片段 ACTH(4-10) 的序列为 Met-Glu-His-Phe-Arg-Trp-Gly，Semax 替换了中间两个残基，并在羧基端延长了 Pro-Gly-Pro 三肽。这种延长被普遍认为能提升分子对肽酶的耐受性。
该化合物于二十世纪八十年代在俄罗斯被开发，相关工作由俄罗斯科学院分子遗传学研究所的研究团队主导。开发目标并非复制 ACTH 的完整激素活性，而是寻找保留其神经作用方向、同时去除促肾上腺皮质激素释放效应的短肽片段。研究记录显示，这一方向促成了多个相关短肽的合成与筛选，而 Semax 是其中被研究最广泛的一个。当地文献常以 Семакс 这一名称指代它。
研究兴趣主要集中在神经营养因子相关的路径上，包括脑源性神经营养因子与神经生长因子的表达变化。部分实验报告称在特定条件下观察到这些因子的水平上升，但具体信号通路和剂量依赖关系仍未完全厘清。多数公开数据来自细胞模型和动物实验，人体对照研究数量有限。因此，该化合物的作用机制在文献中属于活跃讨论，而非已经确立的定论。
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.
| Property | Value | Notes |
|---|---|---|
| 化学类别 | 合成七肽 | ACTH(4-10) 结构类似物 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | 单字母写作 MEHFPGP |
| 分子量 | 约 813.9 Da | 随确切形式和盐型略有变化 |
| 常见同义词 | ACTH(4-10) 类似物 | 俄语文献称 Семакс |
| 开发来源 | 俄罗斯 | 二十世纪八十年代 |
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。
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.
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.
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.
== Chemistry == Omeprazole contains a tricoordinated sulfinyl sulfur in a pyramidal structure and therefore can exist as either the (S)- or (R)-enantiomers. Omeprazole is a racemate, an equal mixture of the two.
==== World War II ==== By World War II, rations had taken modern organized forms for both the Allies and the Axis. The United States Armed Forces revised their World War I-era ration organization system into an alphabetized system: A-rations of fresh food, B-rations of packaged unprepared food, C-rations of prepared canned food, D-rations of chocolate, and K-rations of three-course meals. The US military also issued the 10-in-1 food parcel, designed to supply ten soldiers. A-rations, designed for troops in garrison, included foods such as fresh meat, vegetables, fruits, coffee, and sugar. B-rations, intended for preparation by cooks in field kitchens, contained essentially the same types of foods as A-rations except canned for better preservation. C-rations, intended for troops in the field lacking access to fresh or packaged unprepared food, contained several variations of food combinations, among them meat and beans (including pork and beans), ham, eggs, and potatoes, and chicken and vegetables. D-rations consisted of chocolate bars designed to give needed calories in case soldiers in the field were isolated from any other food source. K-rations were issued to mobile soldiers such as paratroopers, tank crews, and motorcycle couriers. They contained foods such as canned meat, with some canned meat issued together with eggs, carrot or apple, sugar or malted milk tablets, fruit bars, oatmeal, cheese, biscuits, powdered fruit drinks, salt, and chewing gum.
Murphree developing centrifuges, and Arthur Compton responsible for theoretical studies and design. On 23 April 1942, Met Lab scientists discussed seven possible ways to extract plutonium from irradiated uranium, and decided to pursue investigation of all seven. On 17 June, the first batch of uranium nitrate hexahydrate (UNH) was undergoing neutron bombardment in the Washington University in St. Louis cyclotron. On 27 July, the irradiated UNH was ready for Glenn T. Seaborg's team. On 20 August, using ultramicrochemistry techniques, they successfully extracted plutonium. In May 1942, Gertrude Scharff Goldhaber at Brookhaven National Laboratory reports for the first the emission of multiple neutrons during spontaneous fission of uranium. Her research was kept a secret. In April 1939, creating a chain reaction in natural uranium became the goal of Fermi and Szilard, as opposed to isotope separation. Their first efforts involved five hundred pounds of uranium oxide from the Eldorado Radium Corporation. Packed into fifty-two cans two inches in diameter and two feet long in a tank of manganese solution, they were able to confirm more neutrons were emitted than absorbed. However, the hydrogen within the water absorbed the slow neutrons necessary for fission. Carbon in the form of graphite, was then considered, because of its smaller capture cross section. In April 1940, Fermi was able to confirm carbon's potential for a slow-neutron chain reaction, after receiving National Carbon Company's graphite bricks at their Pupin Laboratories.
Sources: en.wikipedia.org
The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. 107Pd versus 107Ag correlations observed in bodies, which have clearly been melted since the accretion of the Solar System, must reflect the presence of live short-lived nuclides in the early Solar System.
=== Transdermal === There are several methods for transdermal delivery of insulin. Pulsatile insulin uses microjets to pulse insulin into the person, mimicking the physiological secretions of insulin by the pancreas. Jet injection had different insulin delivery peaks and durations as compared to needle injection. Some diabetics may prefer jet injectors to hypodermic injection. Both electricity using iontophoresis and ultrasound have been found to make the skin temporarily porous. The insulin administration aspect remains experimental, but the blood glucose test aspect of "wrist appliances" is commercially available Researchers have produced a watch-like device that tests for blood glucose levels through the skin and administers corrective doses of insulin through pores in the skin. A similar device, but relying on skin-penetrating "microneedles", was in the animal testing stage in 2015. In the last couple of years, the use of chemical enhancers, electrical devices, and microneedle devices has shown tremendous promise for improving the penetration of insulin compared to passive transport via the skin. Transdermal insulin delivery shows a more patient-friendly and minimally invasive approach to daily diabetes care than the conventional hypodermic injection however, additional research is necessary to address issues such as long-term use, delivery efficiency, and reliability, as well as side effects involving inflammation and irritation.
==== Russian preparations and invasion of Georgia ==== The commission noted, "the sum of actions undertaken by Russia by mid-2008 amounted to a threat of force vis-à-vis Georgia", and that Georgia felt "a substantial risk of Russian military intervention". The commission noted that "Russian military operations in Georgia in August 2008 appear to most analysts to have been well-planned and well-executed." The commission noted that many international experts "also believe that the massive Russian military action in August 2008 caught the Georgians off guard and unprepared both strategically and tactically." The commission noted that Russian military base Ugardanta in the Dzau District and Russian military rehabilitation centre in the north-west Tskhinvali were constructed before the August 2008 conflict. As far as legality of use of force by Russia was concerned, the report took a "differentiated" approach, dividing "the Russian reaction to the Georgian attack" into two phases – the one, which was "the immediate reaction in order to defend Russian peacekeepers" in Tskhinvali and the second one, "the invasion of Georgia by Russian armed forces reaching far beyond the administrative boundary of South Ossetia", which was "beyond the reasonable limits of defence".
Sources: en.wikipedia.org
evaporation from oceans and other water bodies into the air and transpiration from land plants and animals into the air. precipitation, from water vapor condensing from the air and falling to the earth or ocean. runoff from the land usually reaching the sea. Most water vapors found mostly in the ocean returns to it, but winds carry water vapor over land at the same rate as runoff into the sea, about 47 Tt per year while evaporation and transpiration happening in land masses also contribute another 72 Tt per year. Precipitation, at a rate of 119 Tt per year over land, has several forms: most commonly rain, snow, and hail, with some contribution from fog and dew. Dew is small drops of water that are condensed when a high density of water vapor meets a cool surface. Dew usually forms in the morning when the temperature is the lowest, just before sunrise and when the temperature of the earth's surface starts to increase. Condensed water in the air may also refract sunlight to produce rainbows. Water runoff often collects over watersheds flowing into rivers. Through erosion, runoff shapes the environment creating river valleys and deltas which provide rich soil and level ground for the establishment of population centers. A flood occurs when an area of land, usually low-lying, is covered with water which occurs when a river overflows its banks or a storm surge happens. On the other hand, drought is an extended period of months or years when a region notes a deficiency in its water supply.
2003 First evidence that aging of nematodes is regulated via TOR signaling. 2003 The Methuselah Foundation is organized by Aubrey de Grey and David Gobel to create life extension technologies based on the Strategies for engineered negligible senescence (SENS) approaches and supporting related research in other organizations. 2003 Andrzej Bartke created a mouse that lived 1,819 days (8 days short of 5 years), while the maximum lifespan for this species is 1,030–1,070 days. By human standards, such longevity is equivalent to about 180 years. 2004 First evidence that aging of nematodes is regulated by AMP-Kinase. 2004 Aubrey de Grey coined the term "longevity escape velocity" (LEV). Though the concept per se has been present in the life extension community since at least the 1970s (for example, Robert Wilson, essay Next Stop, Immortality, 1978). 2004 As a result of the use of anti-aging therapy, a team of scientists led by Stephen Spindler managed to extend the life of a group of already adult mice to an average of 3.5 years. For this achievement, the first Methuselah Mouse Rejuvenation 'M Prize' was awarded. 2004 Creation of the first curated database of genes related to human ageing: GenAge. 2006 Creation of induced stem cells (iSC) from somatic cells by the simultaneous action of several factors. First produced by the Japanese scientist Shinya Yamanaka. In 2012, Shinya Yamanaka and John Gurdon received the Nobel Prize for their work on reprogramming mature cells into pluripotent cells. 2007 Extension of mouse lifespan via deletion of insulin receptor in the brain.
== Function == Vitamin D-binding protein belongs to the albumin gene family, together with human serum albumin and alpha-fetoprotein. It is a multifunctional protein found in plasma, ascitic fluid, cerebrospinal fluid (CSF), and on the surface of many cell types. It binds to various forms of vitamin D, including ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3), the 25-hydroxylated forms (calcifediol), and the active hormonal product, 1,25-dihydroxyvitamin D (calcitriol). The major proportion of vitamin D in blood is bound to this protein. Once bound, it transports vitamin D and its plasma metabolites between the skin, liver, and kidney, and then on to the various target tissues. The expression of GC, and therefore the production of GC Vitamin D binding protein, is restricted towards the liver; in an RNA-sequence (RNA-seq) study of tissues samples from 95 human individuals across 27 tissue representations analysed on December 19, 2024, GC was expressed primarily in the tissue of the liver, at a mean RPKM (reads per kilobase million) value of 1258.79 ± 214.721 across 3 samples. In comparison, the next highest RPKM means were in the anatomically nearby gallbladder, at a value of 235.12 ± 73.639 across 3 samples, followed by the stomach, at a value of 23.974 ± 19.053 across 3 samples, the duodenum, at a value of 22.508 ± 6.514 across 2 samples, and the kidney, at a value of 12.033 ± 12.168 across 4 samples. Other tissue samples held a negligible value in comparison to the liver, gallbladder, stomach, duodenum, and kidney.
High-CRI LED lighting – LED lighting source Hiroshi Amano – Japanese materials scientist (born 1960) Isamu Akasaki – Japanese materials scientist (1929–2021) LED Strip Light – Flexible strip of surface mounted light-emitting diodes LED tattoo – Theoretical body modification List of light sources – Devices and processes that produce light MicroLED – Emerging flat-panel display technology Perovskite light-emitting diode – Postulated lighting technology Shuji Nakamura – Japanese–American electronics engineer (born 1954) Superluminescent diode – Optoelectronics component
Sources: en.wikipedia.org
不是。Semax 是完全人工合成的七肽，自然界中没有对应的已知肽段。它的设计灵感来自促肾上腺皮质激素片段 ACTH(4-10)，但序列经过了替换和延长。
Semax 被描述为 ACTH(4-10) 的结构类似物，两者共享部分序列特征。它保留了该片段的部分神经相关活性方向，但去除了完整片段带来的激素释放效应。二者并非同一物质，也不能互相替代。
加入的 Pro-Gly-Pro 三肽被普遍认为能提升分子对蛋白水解酶的稳定性。这种设计让短肽在体内维持时间更长。具体延长的程度以及不同组织中是否一致，文献中仍存在不同报告。
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.