Everything below concerns 反相色谱. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-02-26. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
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。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Contains one methionine sulfur atom |
| Molecular mass | Approximately 814 Da | Consistent with a seven-residue peptide |
| Appearance | White to off-white powder | Typical lyophilized form |
| Solubility | Freely soluble in water | Also soluble in dimethyl sulfoxide |
| Typical storage | -20 °C, desiccated | Limits methionine oxidation |
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
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.
Comfort temperature is interchangeable with neutral temperature in the scientific literature, which can be calculated through regression analysis between thermal sensation votes and indoor temperature. The neutral temperature is the solution of the resulting regression model by setting the thermal sensation vote as zero. The American Heritage Dictionary of the English Language identifies room temperature as around 20–22 °C (68–72 °F; 293–295 K), while the Oxford English Dictionary states that it is "conventionally taken as about 20 °C (68 °F; 293 K)". Ideal room temperature varies vastly depending on the surrounding climate . Studies from Indonesia have shown that the range of comfortable temperature is 24–29 °C (75–84 °F) for local residents. Studies from Nigeria show a comfortable temperature range of 26–28 °C (79–82 °F), comfortably cool 24–26 °C (75–79 °F) and comfortably warm 28–30 °C (82–86 °F). A field study conducted in Hyderabad, India returned a comfort band of 26–32.45 °C (79–90 °F) with a mean of 29.23 °C (85 °F). A study conducted in Jaipur, India among healthy young men showed that the neutral thermal comfort temperature was analyzed to be 30.15 °C (86 °F), although a range of 25.9–33.8 °C (79–93 °F) was found. People are highly sensitive to even small differences in environmental temperature. At 24 °C (75 °F), a difference of 0.38 °C (0.68 °F) can be detected between the temperature of two rooms.
In 1947, the British Indian Empire was partitioned into the independent dominions of a Hindu-majority India and a Muslim-majority Pakistan. The partition brought large-scale loss of life and unprecedented migration. The Constitution of India was adopted in 1950 and declared India to be a federal republic governed through a democratic parliamentary system; it guarantees freedom of speech, freedom of press, and religious pluralism. Amendments enacted from 1951 onwards strengthened affirmative action programmes to reduce caste inequality. The reorganization of states in 1956 along linguistic lines institutionalised regional language pride and led to the growth of regional literature and cinema. During the 1970s, India reversed agricultural stagnation through the Green Revolution, achieving national food security. The country also altered the regional power balance through support for Bangladesh and enacted constitutional reform to end princely privileges. India's population grew from 361 million in 1951 to approximately 1.464 billion in 2025. Economic reforms of the 1990s integrated India's economy with the world's. By the 2010s, the Indian economy had a stably high rate of growth. A large middle class and a communications boom gained momentum. However, challenges remain, including widening income gaps, gender inequality and environmental degradation. In recent years, India has seen a political shift toward majoritarianism.
Crocodile oil is extracted from the fatty tissues of crocodiles. Crocodile fat is a product of commercial farming, evident in Thailand. Historically, for centuries crocodile oil has been used by traditional practitioners across the globe, including Chinese traditional medicine, Southeast Asia, Ancient Egypt. Crocodile oil has been used since the nineteenth century for different purposes in different cultures. Due to the oil's components, its richness in monounsaturated and polyunsaturated fats, it is sold as ointment for treatment of skin conditions, skin structure enhancement, collagen deposition, and medicine for illnesses. In recent times, the use of crocodile oil has invited criticism from the use of crocodile oil as there is an increased demand for cruelty-free and vegan-friendly beauty products in consumers of today's society.
Dermatitis (characteristic "broad collar" rash known as casal collar) Hair loss Swelling Smooth, beefy red glossitis (tongue inflammation) Trouble sleeping Weakness Mental confusion or aggression Ataxia (lack of coordination), paralysis of extremities, peripheral neuritis (nerve damage) Diarrhea Dilated cardiomyopathy (enlarged, weakened heart) Sensitivity to radiation Eventually dementia J. Frostigs and Tom Spies—according to Cleary and Cleary—described more specific psychological symptoms of pellagra as:
Sources: en.wikipedia.org
is the dimensionality of the system. Examples include charge-charge interactions between ions and dipole-dipole interactions between molecules. Modelling these forces presents quite a challenge as they are significant over a distance which may be larger than half the box length with simulations of many thousands of particles. Though one solution would be to significantly increase the size of the box length, this brute force approach is less than ideal as the simulation would become computationally very expensive. Spherically truncating the potential is also out of the question as unrealistic behaviour may be observed when the distance is close to the cut off distance. The most important long-range interactions are electrostatic interactions between two (partly) charge atoms. At present, the most used method is Particle Mesh Ewald (PME). PME uses Ewald summations to split the calculations into a short- and long range part. The short-range part calculates all interactions within a cut-off range, the long-range part is solved in reciprocal space, using fast Fourier transforms (FFTs). The high accuracy and high calculation speed made PME the gold standard for many years. However the increase use of parallelization, PME runs into a communication bottleneck because the FFTs require an all-to-all communication. A attractive PME alternative are the fast multipole methods (FMM), which are not affected by an increase in parallelization.
== Annual events == Fellows in American Letters of the Library of Congress Gershwin Prize for Popular Song Library of Congress Prize for American Fiction Founder's Day Celebration Mostly Lost Film Identification Workshop National Book Festival
Submarine springs found along the coast of Mexico's Yucatán Peninsula produce water with a naturally low pH (relatively high acidity) providing conditions similar to those expected to become widespread as the oceans absorb carbon dioxide. Surveys discovered multiple species of live coral that appeared to tolerate the acidity. The colonies were small and patchily distributed and had not formed structurally complex reefs such as those that compose the nearby Mesoamerican Barrier Reef System.
=== Sagan's finer classification === In 1973, Carl Sagan discovered Kardashev's work on the classification of civilizations. He found that the differences between the types Kardashev identified were so great that they did not allow for the best possible modeling of the evolution of civilizations. Consequently, Sagan proposed a more refined classification, still based on Kardashev's types, but integrating intermediate levels using the following logarithmic interpolation formula:
Chemical fixatives are used to preserve and maintain the structure of tissues and cells; fixation also hardens tissues which aids in cutting the thin sections of tissue needed for observation under the microscope. Fixatives generally preserve tissues (and cells) by irreversibly cross-linking proteins. The most widely used fixative for light microscopy is 10% neutral buffered formalin, or NBF (4% formaldehyde in phosphate buffered saline). For electron microscopy, the most commonly used fixative is glutaraldehyde, usually as a 2.5% solution in phosphate buffered saline. Other fixatives used for electron microscopy are osmium tetroxide or uranyl acetate. The main action of these aldehyde fixatives is to cross-link amino groups in proteins through the formation of methylene bridges (−CH2−), in the case of formaldehyde, or by C5H10 cross-links in the case of glutaraldehyde. This process, while preserving the structural integrity of the cells and tissue can damage the biological functionality of proteins, particularly enzymes. Formalin fixation leads to degradation of mRNA, miRNA, and DNA as well as denaturation and modification of proteins in tissues. However, extraction and analysis of nucleic acids and proteins from formalin-fixed, paraffin-embedded tissues is possible using appropriate protocols.
Sources: en.wikipedia.org
== Ownership == In 2002, Laboratory Corporation of America Holdings (LabCorp), a clinical lab provider based in the United States, acquired Dynacare Laboratories. LabCorp purchased all of Dynacare's outstanding shares for US$480 million and assumed Dynacare's debt of US$205 million. At the time of purchase, Dynacare medical laboratories provided services in Canada and in 21 American states. The Globe and Mail reported that the takeover would not have an effect on "Dynacare's operational partnerships with Gamma NorthPeel and Bio-Science Laboratory in Ontario and with Kasper Medical Laboratories and MDS Laboratories in Alberta".
Prince August Wilhelm Heinrich Günther Viktor of Prussia (29 January 1887 – 25 March 1949), nicknamed "Auwi", was the fourth son of German Emperor Wilhelm II by his first wife, Augusta Victoria of Schleswig-Holstein. A vocal supporter of Nazism and of Adolf Hitler, he joined the Nazi party in 1930 and rose to the rank of SA-Obergruppenführer.
An MRI artifact is a visual artifact, that is, an anomaly during visual representation. Many different artifacts can occur during magnetic resonance imaging (MRI), some affecting the diagnostic quality, while others may be confused with pathology. Artifacts can be classified as patient-related, signal processing-dependent and hardware (machine)-related.
=== Cancer === While Aβ has been implicated in cancer development, prompting studies on a variety of cancers to elucidate the nature of its possible effects, results are largely inconclusive. Aβ levels have been assessed in relation to a number of cancers, including esophageal, colorectal, lung, and hepatic, in response to observed reductions in risk for developing Alzheimer's disease in survivors of these cancers. All cancers were shown to be associated positively with increased Aβ levels, particularly hepatic cancers. This direction of association however has not yet been established. Studies focusing on human breast cancer cell lines have further demonstrated that these cancerous cells display an increased level of expression of amyloid precursor protein.
Medical schools began to be set up in the United States towards the end of the 18th century. Classes in anatomy needed a continual stream of cadavers for dissection, and these were difficult to obtain. Philadelphia, Baltimore, and New York were all renowned for body snatching activity as criminals raided graveyards at night, removing newly buried corpses from their coffins. A similar problem existed in Britain where demand for bodies became so great that grave-raiding and even anatomy murder were practised to obtain cadavers. Some graveyards were, in consequence, protected with watchtowers. The practice was halted in Britain by the Anatomy Act of 1832, while in the United States, similar legislation was enacted after the physician William S. Forbes of Jefferson Medical College was found guilty in 1882 of "complicity with resurrectionists in the despoliation of graves in Lebanon Cemetery".The teaching of anatomy in Britain was transformed by Sir John Struthers, Regius Professor of Anatomy at the University of Aberdeen from 1863 to 1889. He was responsible for setting up the system of three years of "pre-clinical" academic teaching in the sciences underlying medicine, including especially anatomy. This system lasted until the reform of medical training in 1993 and 2003. As well as teaching, he collected many vertebrate skeletons for his museum of comparative anatomy, published over 70 research papers, and became famous for his public dissection of the Tay Whale. From 1822 the Royal College of Surgeons regulated the teaching of anatomy in medical schools.
Sources: en.wikipedia.org
It is registered as a pharmaceutical product in Russia, where it is typically supplied as a nasal solution. In most other countries it is not an approved drug and is traded as a research chemical instead. Approval status depends entirely on the jurisdiction involved.
Most published work uses intranasal administration, matching the route of the registered Russian formulation. Some animal experiments use intravenous or intraperitoneal injection. The route matters because the intact peptide is cleared rapidly from blood, so exposure differs between methods.
A purity value describes the share of the powder accounted for by the target peptide, usually by high-performance liquid chromatography. It does not confirm that the sequence is correct, which requires mass spectrometry or amino acid analysis. Purity and identity are separate checks.
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。