A practical reference on Electrospray ionization: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-07-17. Anything still debated is marked as such rather than presented as settled.
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。
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.
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
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.
=== Hoogsteen base pairing === A thymine (T) nucleobase can bind to a Watson–Crick base-pairing of T-A by forming a Hoogsteen hydrogen bond. The thymine hydrogen bonds with the adenosine (A) of the original double-stranded DNA to create a T-A*T base-triplet.
== Etymology, usage, and history of -gate == The suffix -gate derives from the Watergate scandal in the United States in the early 1970s, which resulted in the resignation of US President Richard Nixon. The scandal was named after the Watergate complex in Washington, D.C., where the burglary giving rise to the scandal took place; the complex itself was named after the "Water Gate" area where symphony orchestra concerts were staged on the Potomac River between 1935 and 1965. The suffix has become productive as a libfix and is used to embellish a noun or name to suggest the existence of a far-reaching scandal, particularly in politics and government. As a CBC News column noted in 2001, the term may "suggest unethical behavior and a cover-up". The use of “—gate” served well in an era of sound bites politics. Because they were short and memorable, these phrases caught the attention of the public — and because of its origin [Watergate] it carried a stigma around it, making lesser-known scenarios seem more important. Such usage has been criticized by some commentators as clichéd and misleading. James Stanyer comments that "revelations are given the 'gate' suffix to add a thin veil of credibility, following 'Watergate', but most bear no resemblance to the painstaking investigation of that particular piece of presidential corruption". Stanyer links the widespread use of -gate to what the sociologist John Thompson calls "scandal syndrome":
Since 2023 the European Commission Regulation 2023/915 states that processing contaminants of food though PAHs are not allowed to exceed a sum of 4 PAHs for BaP in order to protect public health. BaP is discharged in wastewater by industries such as smelters, particularly iron and steel mills and aluminium smelters.
Sources: en.wikipedia.org
=== Disinfection === Secretions from maggots believed to have broad-spectrum antimicrobial activity include allantoin, urea, phenylacetic acid, phenylacetaldehyde, calcium carbonate, proteolytic enzymes, and many others. In vitro studies have shown that maggots inhibit and destroy a wide range of pathogenic bacteria including methicillin-resistant Staphylococcus aureus (MRSA), group A and B streptococci, and Gram-positive aerobic and anaerobic strains. Other bacteria like Pseudomonas aeruginosa, E. coli or Proteus spp. are not attacked by maggots, and in case of Pseudomonas even the maggots are in danger.
The government claims modern retail will create 4 million new jobs. This cannot be true because Walmart, with over 9000 stores worldwide, has only 2.1 million employees. By allowing modern retail there could be more stores in total than Walmart has over the world, it's not unfeasible for 20,000 stores in India which would indeed create more than 4 million jobs. Let's not forget that India has ~3 times the population of the United States. The Democratic staff of the U.S. House Committee on Education and the Workforce Report- Wal-Mart's low wages and their effect on taxpayers and economic growth. Supporters claim none of these objections has merit. They claim:
Unlike aerated chocolates produced with large bubbles, micro-aerated chocolate has nitrogen beaten into the mixture. The resulting chocolate, different not only in bubble size but also flavour and texture. This is theorised to arise from the gas having a different solubility. Aerated chocolates containing long tubes of air are also created using this technique, but their distinction comes from how the aerated chocolate is extruded rather than set in a moulded shell. The final type, those held together by a skeleton of solid particles, are produced using water evaporation methods. In the first of these, sugar is dissolved in water. This solution is emulsified with cocoa liquor and milk solids, which is evaporated and then dried using industrial machinery, until the product contains less than 2% water. In the second, water is emulsified with liquid chocolate and set and then freeze dried, removing the water.
Sources: en.wikipedia.org
==== Surfactants ==== The purpose of surfactants is to mobilize various components of NAPLs by lowering their viscosity and interfacial tension. Solubilizing agents increase the solubility of NAPLs and transfer it to the aqueous phase, allowing it to then be extracted and treated. Mobilizing agents target the residually saturated component of NAPL, allowing it to be displaced by continuous flooding. While surfactants are highly effective, resulting in recovery of 94% of the original DNAPL in case studies, they are also expensive and cost-prohibitive, also potentially adversely affecting the pH of the subsurface environment.
A parallelized version of pyrosequencing was developed by 454 Life Sciences, which has since been acquired by Roche Diagnostics. The method amplifies DNA inside water droplets in an oil solution (emulsion PCR), with each droplet containing a single DNA template attached to a single primer-coated bead that then forms a clonal colony. The sequencing machine contains many picoliter-volume wells each containing a single bead and sequencing enzymes. Pyrosequencing uses luciferase to generate light for detection of the individual nucleotides added to the nascent DNA, and the combined data are used to generate sequence reads. This technology provides intermediate read length and price per base compared to Sanger sequencing on one end and Solexa and SOLiD on the other.
Knoxville's Greek community is perhaps best known for its restaurateurs, namely the Regas family, who operated a restaurant on North Gay Street from 1919 to 2010, and the Paskalis family, who founded the Gold Sun Cafe on Market Square around 1909. Notable members of Knoxville's Jewish community included jeweler Max Friedman and department store owner Max Arnstein. One of Knoxville's largest migrant groups consisted of rural people who moved to the city from the surrounding rural counties, often seeking wage-paying jobs in mills. Many of Knoxville's political and business leaders throughout the 20th century hailed from rural areas of Southern Appalachia.
Sources: en.wikipedia.org
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
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.