Everything below concerns lyophilization. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-12-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
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.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C37H51N9O10S | 游离碱形式 |
| 等电点 | 约 6.5 | 估算值，随缓冲体系变化 |
| 主要降解途径 | 水解与氧化 | 侧链氧化最为常见 |
| 溶液储存 | 2 至 8 摄氏度避光 | 避免反复冻融 |
| 常规分析手段 | 反相色谱与质谱联用 | 氨基酸分析辅助核对 |
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
溶液状态的稳定性明显低于冻干粉。肽类在水溶液中可能经历水解、氧化与聚集，其中甲硫氨酸和天冬酰胺等残基常是敏感位点。Semax 含有甲硫氨酸，因此氧化风险相对突出。工作液一般主张现配现用，或冷藏并在数日内用尽。缓冲液种类、pH 和离子强度都会影响降解速率，而关于最佳条件的公开数据并不统一。
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
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.
=== Addiction and dependence liability === LSD is widely considered to be non-addictive, despite its potential for abuse. Attempts to train laboratory animals to self-administer LSD have been largely unsuccessful. Although tolerance to LSD builds up rapidly, a withdrawal syndrome does not appear, suggesting that a potential syndrome does not necessarily relate to the possibility of acquiring rapid tolerance to a substance. A report examining substance use disorder for DSM-IV noted that almost no hallucinogens produced dependence, unlike psychoactive drugs of other classes such as stimulants and depressants.
=== Direct reaction of metal with carbon monoxide === Nickel tetracarbonyl and iron pentacarbonyl can be prepared according to the following equations by reaction of finely divided metal with carbon monoxide:
== Energy consumption == Due to the low temperature, ULT freezers consume high amounts of electric energy and hence are expensive to operate. In 2010, Stanford University had more than 2,000 ULT freezers, which used an estimated 40 billion BTUs of energy and cost the university $5.6 million annually. Newer ULT freezers consume less energy. Nonetheless, a comprehensive report published in 2015 by the Center for Energy Efficient Laboratories (funded by Pacific Gas & Electric, Southern California Edison, and San Diego Gas & Electric utility companies as part of their Emerging Technologies program) found that laboratories in California consumed an estimated 800 GWh/year, with ULT freezers being the greatest contributor to that total. At least as early as 2018, some scientists suggested that laboratories set freezers to –70 °C instead of –80 °C to conserve energy and decrease wear on the freezer's compressor. Depending on the volume of the freezer, the opening frequency of the users as well as the number of samples, the energy consumption starts from ca. 11 kWh/day and higher. The US government calculates 20 kWh/day. A study performed at the University of Edinburgh showed that the New Brunswick U570 HEF model consumed slightly under 10 kWh/day. Without any data, the University of Michigan claimed that "older model" ULT devices could consume "up to 30 kWh/day". A sales pitch written in 2023 quoted "16-22 KWh of electricity per day". To reduce the energy consumption, the insulation should be as efficient as possible.
May 20, 2009: Mexico Mexico becomes the first Latin American country to officially enter recession, having its GDP shrink 8.22% in the first quarter of 2009, after falling 1.6% in the final quarter of 2008. To this date, it is estimated that the Mexican domestic product will shrink 5.5% in 2009. Ministry of Finances Agustin Carstens declared the country in recession on May 7, 2009, based on estimates, which were confirmed when the actual, real data was released on May 20 by INEGI.
Sources: en.wikipedia.org
A crate is a large container, often made of wood, used to transport large, heavy or awkward items. A crate has a self-supporting structure, with or without sheathing. Reusable plastic versions include:
Murine respirovirus, now Respirovirus muris, formerly Sendai virus (SeV) and previously also known as murine parainfluenza virus type 1 or hemagglutinating virus of Japan (HVJ), is an enveloped, 150–200 nm diameter, negative sense, single-stranded RNA virus of the family Paramyxoviridae. It typically infects rodents and it is not pathogenic for humans or domestic animals. Respirovirus muris is a member of the genus Respirovirus. The virus was isolated in the city of Sendai in Japan in the early 1950s. Since then, it has been actively used in research as a model pathogen. The virus is infectious for many cancer cell lines (see below), and has oncolytic properties demonstrated in animal models and in naturally occurring cancers in animals. Its ability to fuse eukaryotic cells and to form syncytium was used to produce hybridoma cells capable of manufacturing monoclonal antibodies in large quantities. Recent applications of SeV-based vectors include the reprogramming of somatic cells into induced pluripotent stem cells and vaccine creation. For vaccination purpose the Sendai virus-based constructs could be delivered in a form of nasal drops, which may be beneficial in inducing a mucosal immune response. SeV has several features that are important in a vector for a successful vaccine: the virus does not integrate into the host genome, it does not undergo genetic recombination, it replicates only in the cytoplasm without DNA intermediates or a nuclear phase and it does not cause any disease in humans or domestic animals.
Scott in 1951 published a protocol described as "the advent of the modern blood culture set". Scott's method involved inoculating blood into two rubber-sealed glass bottles; one for aerobes and one for anaerobes. The aerobic bottle contained trypticase soy broth and an agar slant, and the anaerobic bottle contained thioglycollate broth. The lysis-centrifugation method was introduced in 1917 by Mildred Clough, but it was rarely used in clinical practice until commercial systems were developed in the mid-1970s. Automated blood culture systems first became available in the 1970s. The earliest of these—the BACTEC systems, produced by Johnston Laboratories (now Becton Dickinson)—used culture broths containing nutrients labelled with radioactive isotopes. Microbes that fed on these substrates would produce radioactive carbon dioxide, and growth could be detected by monitoring its concentration. Before this technique was applied to blood cultures, it had been proposed by NASA as a method for detecting life on Mars. Throughout the 1970s and 80s several manufacturers attempted to detect microbial growth by measuring changes in the electrical conductivity of the culture medium, but none of these methods were commercially successful. A major issue with the early BACTEC systems was that they produced radioactive waste, which required special disposal procedures, so in 1984 a new generation of BACTEC instruments was released that used spectrophotometry to detect CO2.
Sources: en.wikipedia.org
== Further reading == Cook, E.M, and DuMont, H.D. (1991) Process Drying Practice, McGraw-Hill, Inc., ISBN 0-07-012462-0 Keey, R.B., (1992). Drying of Loose and Particulate Materials 1st ed., Taylor & Francis, ISBN 0-89116-878-8 Nutritional evaluation of food processing second edition (1975), Robert S. Harris, Ph.D. and Endel Karmas Ph.D. (eds) Filková, I., & Mujumdar, A. S. (2020). Industrial spray drying systems. In Handbook of industrial drying (pp. 263-307). CRC Press. Jafari, S. M., Arpagaus, C., Cerqueira, M. A., & Samborska, K. (2021). Nano spray drying of food ingredients; materials, processing and applications. Trends in Food Science & Technology, 109, 632-646. Klimša, V., Ruphuy, G., Jonáš, J., Mašková, L., Kašpar, O., Žvátora, P., & Štěpánek, F. (2023). Spray drying robot for high-throughput combinatorial fabrication of multicomponent solid dispersions. Powder Technology, 428, 118872.
Similarly, maritime crossings across the Taiwan Strait require special permits from both the People's Republic of China and the Republic of China and are usually off-limits to foreign vessels. In India, foreign vessels engaging in the coasting trade require a licence that is generally only issued when no local vessel is available. Similarly, a foreign vessel may only be issued a licence to engage in cabotage in Brazil if there are no Brazilian flagged vessels available for the intended transport. As with maritime cabotage, most jurisdictions heavily restrict cabotage in passenger aviation, though rules regarding air cargo are typically more lax. Passenger cabotage is not usually granted under most open skies agreements. Air cabotage policies in the European Union are uniquely liberal insofar as carriers licensed by one member state are permitted to engage in cabotage in any EU member state, with few limitations. Chile has the most liberal air cabotage rules in the world, enacted in 1979, which allow foreign airlines to operate domestic flights, conditional upon reciprocal treatment for Chilean carriers in the foreign airline's country. Countries apply special provisions to the ability of foreign airlines to carry passengers between two domestic destinations through an offshore hub. Many countries implement air defence identification zones (ADIZs) requiring aircraft approaching within a specified distance of their airspace to contact or seek prior authorization from their military or transport authorities.
peripheral membrane protein Also extrinsic membrane protein. Any of a class of membrane proteins which attach only temporarily to the cell membrane, either by penetrating the lipid bilayer or by attaching to other proteins which are permanently embedded within the membrane. The ability to reversibly interact with membranes makes peripheral membrane proteins important in many different roles, commonly as regulatory subunits of channel proteins and cell surface receptors. Their domains often undergo rearrangement, dissociation, or conformational changes when they interact with the membrane, resulting in the activation of their biological activity. In protein purification, peripheral membrane proteins are typically more water-soluble and much easier to isolate from the membrane than integral membrane proteins.
Sources: en.wikipedia.org
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。
甲硫氨酸侧链含硫醚，在氧气、光照或金属离子存在时容易被氧化。氧化产物极性略增，常在色谱图上表现为主峰之前的肩峰或前伸峰。
通常建议冷藏避光，并在较短时间内使用。不存在适用于所有配方的统一期限，具体取决于浓度、缓冲体系与容器材质。
It consists mainly of animal experiments and small clinical reports, with much of the clinical material published in Russian-language journals. Large independent trials are scarce. Separating reliable effects from chance findings is consequently difficult.