freeze-thaw cycling is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-05-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
市售的胸腺素α1通常以冻干粉形式提供，溶解后用于注射。其氨基酸组成包括多个酸性残基，因此在中性pH下带负电荷。该肽可溶于水和生理盐水，但在有机溶剂中溶解度有限。储存条件通常为冻干状态下负20摄氏度，溶解后需冷藏并避免反复冻融。常见的同义词包括胸腺肽α1、thymalfasin和Tα1。
胸腺素α1（thymosin alpha 1，Tα1）是一种由28个氨基酸组成的酸性肽，N端被乙酰化，分子量约为3108道尔顿。该肽最早从牛胸腺组织提取物中分离，属于胸腺素组分5的一个成分。其序列在不同哺乳动物中高度保守，提示其具有基本的生物学功能。名称中的“α1”指其在电泳中的迁移位置，并非表示亚型编号。它既存在于胸腺，也存在于脾脏和淋巴结等免疫组织。
Immunological studies connect the peptide to multiple parts of the immune response. It has been reported to engage Toll-like receptor signaling, to promote dendritic cell maturation, and to influence the balance of T helper cell subsets. Changes in natural killer cell activity and in cytokine release appear in cell culture and animal models. These observations describe broad immunomodulatory behavior rather than a single defined receptor target, and the primary molecular interaction has not been settled.
Thymosin alpha-1 is a synthetic 28-amino-acid peptide whose sequence was first identified in extracts of bovine thymus tissue during the 1970s. The chain carries an acetyl group on its N-terminal serine. Its acidic residue content is high, which produces strong water solubility and an isoelectric point well below neutrality. Material supplied for laboratory and clinical use is manufactured by solid-phase peptide synthesis rather than purified from animal tissue. Different salt forms, such as the acetate, alter the counter-ion content without changing the peptide backbone.
Whether the free 28-residue peptide circulates in human tissue remains debated. The best-documented human source is prothymosin alpha, a larger acidic protein that carries the sequence at its N-terminus. Reports of measurable peptide levels in serum and lymphoid tissue exist, yet some of that signal may come from cross-reacting fragments or from the parent protein. Most reviews therefore treat prothymosin alpha as the established human molecule and describe independent circulation of the small peptide as an unresolved question.
| Property | Value | Notes |
|---|---|---|
| 化学分类 | 线性肽 | 由28个氨基酸组成 |
| 分子量 | 约3108 Da | 合成版本一致 |
| 外观 | 白色至类白色粉末 | 冻干品 |
| 溶解度 | 易溶于水 | 微溶于有机溶剂 |
| 储存温度 | -20°C（冻干） | 溶解后2-8°C |
Within the immune system, the peptide acts on several cell types rather than a single target. Reported activities include promotion of T-cell maturation, enhancement of natural killer cell activity, and modulation of cytokine production by dendritic cells and macrophages. Some of these effects appear to operate through toll-like receptor signaling, though the precise receptor-level mechanism remains debated. Whether the observed immune changes translate into clinical benefit is a separate question and depends on the indication studied.
The peptide was described in the 1970s as a component of thymic extracts, and early research focused on restoring immune function in immunodeficiency states. A synthetic version entered clinical development in the 1980s and is approved as a drug in several countries for conditions such as chronic hepatitis B and certain immunodeficiencies. Approval status varies widely by jurisdiction, and in the United States it is not an approved therapeutic. Regulatory and clinical positions differ, so statements about efficacy should be tied to specific indications and studies.
Thymosin alpha-1 is a synthetic peptide of 28 amino acids, corresponding to the N-terminal fragment of prothymosin alpha. Its sequence begins with acetylation at the N-terminus, a modification that affects stability and receptor interaction. The peptide is acidic, with a calculated isoelectric point near 4.2, and carries no disulfide bonds, so its secondary structure is largely flexible in solution. Molecular mass is approximately 3108 daltons. The native form was first isolated from bovine thymus tissue, while pharmaceutical material is produced by solid-phase peptide synthesis.
Thymosin alpha-1 is a synthetic peptide of 28 amino acid residues that corresponds to a naturally occurring fragment first isolated from thymus tissue. Its chain is acetylated at the amino terminus, a modification that shields the peptide from rapid cleavage by aminopeptidases. The molecule carries a net negative charge at physiological pH and dissolves freely in water. Researchers classify it as an immune-modulating agent rather than a classical hormone, because it acts on several cell types of both the innate and the adaptive immune system.
The peptide was identified during work in the 1970s on thymosin fraction 5, a partially purified extract of calf thymus. Investigators separated that mixture and characterized individual components, one of which they named thymosin alpha-1. The same compound later received the international nonproprietary name thymalfasin. Commercial material is produced by solid-phase peptide synthesis rather than by extraction, so synthetic and natural forms share an identical sequence. Naming conventions vary across the literature, and readers should distinguish the alpha-1 peptide from other thymosins that have unrelated sequences and functions.
Stability depends on temperature, pH, and the number of freeze-thaw events the sample has experienced. Freeze-dried material is commonly held at -20 °C or colder, while reconstituted liquid is kept cold and used within a short window. Extreme pH and prolonged light exposure can promote deamidation, oxidation, or aggregation, particularly at asparagine and methionine positions. Adsorption to container walls can lower the measured concentration of a dilute solution even when the peptide molecules themselves remain intact.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or chemically modified byproducts. Mass spectrometry confirms the expected molecular mass and can indicate acetylation state or sequence errors. Amino acid analysis and peptide mapping supply complementary sequence-level information, while endotoxin testing is relevant for preparations intended for cell or animal work. Purity figures reported by suppliers refer to the method used and are not directly comparable across laboratories unless conditions are stated.
Lyophilized material is typically treated as a hygroscopic solid that should be brought to room temperature before the container is opened, which limits condensation on the powder. Reconstitution is commonly done with sterile water or a buffered diluent, and gentle mixing is preferred over vigorous agitation to reduce foaming and surface adsorption. Because peptides can bind to plastic and glass, diluents containing a small amount of carrier protein are sometimes used in laboratory work. Working solutions are generally aliquoted and prepared fresh rather than subjected to repeated freezing and thawing.
The purpose of using the vacuum is to eliminate background signal and avoid intermolecular collision events, therefore, providing a long mean free path for the ions. The vacuum system, including the vacuum pumps and the vacuum manifold with its various interfaces, is often the heaviest part and consumes the most power in a mass spectrometer. In the case of TOF, if the length of drift region is decreased, the pressure inside region can be operated at higher value because the free collision region is still maintained for a short traveling distance of the ions. As a result, the vacuum system requires less power to run the system. For a trap-type mass analyzer, because the ions are trapped in the device for long periods and the accumulated trajectory length is much longer than the size of the mass analyzer, the size reduction of the mass analyzer may not directly affect the adequate operating pressure. Miniature rough-turbo pump configurations similar to lab-scale instruments have been developed to be compatible with MMS. For high-vacuum pumping, turbomolecular pumps are also upgraded. A Thermo Fisher Orbitrap used three turbo pumps in LC-MS modes to achieve a vacuum below 10−10 torr. Recently, a turbo pump from Creare, Inc.TM weighs only 500g and needs below 18 W power to run. The pump can provide the ultimate vacuum below 10−8 torr, which is much lower than the operating pressure necessary for a MMS.
Packages can be made with improved tamper resistance to deter tampering, and can also have tamper-evident features to help indicate tampering. Packages can be engineered to help reduce the risk of package pilferage; some package constructions are more resistant to pilferage, and some have pilfer-indicating seals. Packages may include authentication seals to help indicate that the package and contents are not counterfeit. Packages also can include anti-theft devices, such as dye packs, RFID tags, or electronic article surveillance tags, that can be activated or detected by devices at exit points and require specialized tools to deactivate. Using packaging in this way is a means of retail loss prevention. Convenience - Packages can have features which add convenience in distribution, handling, stacking, display, sale, opening, reclosing, use, and reuse. Portion control - Single-serving packaging has a precise amount of contents to control usage. Bulk commodities (such as salt) can be divided into packages that are a more suitable size for individual households. It also aids the control of inventory: selling sealed one-liter bottles of milk, rather than having people bring their own bottles to fill themselves.
India had a large, consumption-driven middle class and witnessed a communications boom. However, India's economic growth has been accompanied by widening income gaps, gender inequality, and degradation of the environment. In recent years, India has witnessed a shift toward majoritarianism and Hindu nationalism, which has led to democratic erosion.
== Prognosis == Urbach–Wiethe disease is typically not a life-threatening condition. The life expectancy of these patients is normal as long as the potential side effects of thickening mucosa, such as respiratory obstruction, are properly addressed. Although this may require a tracheostomy or carbon dioxide laser surgery, such steps can help ensure that individuals with Urbach–Wiethe disease are able to live a full life. Oral dimethyl sulfoxide (DMSO) has been shown to reduce skin lesions, helping to minimize discomfort for these individuals.
Seafood is any form of sea life regarded as food by humans, prominently including fish and shellfish. Shellfish include various species of molluscs (e.g., bivalve molluscs such as clams, oysters, and mussels, and cephalopods such as octopus and squid), crustaceans (e.g. shrimp, crabs, and lobster), and echinoderms (e.g. sea cucumbers and sea urchins). Historically, marine mammals such as cetaceans (whales and dolphins) as well as seals have been eaten as food, though that happens to a lesser extent in modern times. Edible sea plants such as some seaweeds and microalgae are widely eaten as sea vegetables around the world, especially in Asia. Seafood is an important source of (animal) protein in many diets around the world, especially in coastal areas. Semi-vegetarians who consume seafood as the only source of meat are said to adhere to pescetarianism. The harvesting of wild seafood is usually known as fishing or hunting, while the cultivation and farming of seafood is known as aquaculture and fish farming (in the case of fish). Most of the seafood harvest is consumed by humans, but a significant proportion is used as fish food to farm other fish or rear farm animals. Some seafoods (i.e. kelp) are used as food for other plants (a fertilizer). In these ways, seafoods are used to produce further food for human consumption. Also, products such as fish oil, spirulina tablets, fish collagen, and chitin are made from seafoods. Some seafood is fed to aquarium fish, or used to feed domestic pets such as cats.
Sources: en.wikipedia.org
==== Vertebrates ==== For the wood frog (Rana sylvatica), in the winter, as much as 45% of its body may freeze and turn to ice. "Ice crystals form beneath the skin and become interspersed among the body's skeletal muscles. During the freeze, the frog's breathing, blood flow, and heartbeat cease. Freezing is made possible by specialized proteins and glucose, which prevent intracellular freezing and dehydration." The wood frog can survive up to 11 days frozen at -4 °C. Other vertebrates that survive at body temperatures below 0 °C include painted turtles (Chrysemys picta), gray tree frogs (Hyla versicolor), moor frogs (Rana arvalis), box turtles (Terrapene carolina - 48 hours at -2 °C), spring peeper (Pseudacris crucifer), garter snakes (Thamnophis sirtalis- 24 hours at -1.5 °C), the chorus frog (Pseudacris triseriata), Siberian salamander (Salamandrella keyserlingii - 24 hours at -15.3 °C), European common lizard (Lacerta vivipara) and Antarctic fish such as Pagothenia borchgrevinki. Antifreeze proteins cloned from such fish have been used to confer frost-resistance on transgenic plants. Hibernating Arctic ground squirrels may have abdominal temperatures as low as −2.9 °C (26.8 °F), maintaining subzero abdominal temperatures for more than three weeks at a time, although the temperatures at the head and neck remain at 0 °C or above.
== Structure and properties == The molecular weight of lactate racemase differs in the various organisms in which it has been found, ranging from 25,000 to 82,400 g/mol. The structure of the enzyme from L. plantarum was solved by Jian Hu and Robert P. Hausinger of Michigan State University and co-workers there and elsewhere. The protein contains a previously unknown covalently-linked nickel-pincer nucleotide (NPN) cofactor (pyridinium 3-thioamide-5-thiocarboxylic acid mononucleotide), where the nickel atom is bound to C4 of the pyridinium ring and two sulfur atoms. This cofactor participates in a proton-coupled hydride-transfer mechanism. There have been a number of recent studies on NPN cofactor synthesis by the LarB, LarE, and LarC proteins. LarB is a carboxylase/hydrolase of nicotinamide adenine dinucleotide (NAD), providing pyridinium-3,5-dicarboxylic acid mononucleotide and adenosine monophosphate (AMP). LarE is an ATP-dependent sulfur transferase that converts the two substrate carboxyl groups into thioacids by sacrificing the sulfur atoms of a cysteine residue in the protein. Finally, LarC inserts nickel into the organic ligand by a CTP-dependent process to complete synthesis of the NPN cofactor.
=== Maxim Alonso === Maxim Alonso (Nicholas Bishop) is a hedge fund manager and old family friend of Yasmin's, placed in charge of overseeing her father Charles' assets. Maxim has a tense, quasi-brotherly relationship with Yasmin throughout series 1, especially after a client meeting with him is derailed by the misbehavior of Yasmin's abusive boss Kenny. In series 2, Maxim's fund goes bankrupt, prompting him to throw an excessive, drug-fueled party where and Yasmin end up having sex. While initially continuing their tryst, Yasmin grows distant from Maxim after becoming privy to Charles' numerous extramarital affairs and subsequent NDA settlements, which she is angry at Maxim for not telling her about. Maxim later drunkenly tries to force himself on Yasmin in bed, causing her to cut ties with him. In series 3, Maxim reaches out to Yasmin while camping in Northern California to tell her that Hanani Publishing was complicit in Charles' sexual misconduct, providing several of his victims with sham jobs in exchange for their silence. He explains that the company wants to make Yasmin the face of the scandal to hide their own involvement.
The design of baby bottles and particularly the ease of cleaning them had potentially serious consequences for the health of the children using them. Estimates of infant mortality suggest that 20-30% of infants died in the first year of life during the late Victorian era. During the 1890s, at a time when England's childhood mortality rates (ages 1–5) were declining, infant mortality rates actually rose. A bottle with a long Indian rubber tube ending in a teat remained popular until the 1920s because even very young babies could feed independently. The feeding tubes could be bought separately and were sometimes used with empty whiskey or medicine bottles. Almost impossible to keep clean, this type has been nicknamed the "murder bottle".
Sources: en.wikipedia.org
42 BC to at least early 5th century, Mark Antony (emblem: capricorn) Legio V Macedonica (Macedonian): 43 BC – AD 637, Octavian (emblem: bull) Legio V Alaudae (Larks): 52 BC – AD 70 or 86 (destroyed either during the Batavian rebellion or by the Dacians in first Battle of Tapae), Julius Caesar (emblem: elephant) Legio VI Ferrata (Ironclad): 52 BC – after AD 250, Julius Caesar (emblem: bull, she-wolf and Romulus and Remus); twin legion of Legio VI Victrix Legio VI Victrix (Victorious): 41 BC – after AD 402, Octavian (emblem: bull) Legio VII Claudia Pia Fidelis (loyal and faithful to Claudius): before 58 BC – 44 BC, Julius Caesar; disbanded and re-formed by Octavian Legio VIII Augusta: 59 BC – 46 BC, Julius Caesar, originally named Gallica, disbanded and re-enlisted by Octavian as Legio VIII Augusta, 44 BC – AD 420 Legio IX Hispana (Hispanian): before 58 BC – AD 120-161 Legio X Equestris (Equestrian): before 58 BC – 45 BC, Julius Caesar's personal legion, later renamed as Legio X Gemina Legio X Fretensis (of the sea strait): levied by Octavian in 41/40 BC, recorded to have existed at least until the 410s Legio XI Claudia: 58 BC – 45 BC, Julius Caesar (emblem: Neptune), disbanded, reconstituted by Octavian Legio XII Fulminata (Thunderbolt): 57 BC – AD 45, Julius Caesar, first reconstituted by Lepidus in 43 BC, named by Mark Antony as Legio XII Antiqua (Ancient) Legio XIII Gemina (Twin): 57 BC – 45 BC: Julius Caesar, later (41 BC) reconstituted by Octavian. The legion that crossed the Rubicon with Caesar on his assault on Rome.
Potassium alum, potash alum, or potassium aluminium sulfate is a chemical compound defined as the double sulfate of potassium and aluminium, with chemical formula KAl(SO4)2. It is commonly encountered as the dodecahydrate, KAl(SO4)2·12H2O. It crystallizes in an octahedral structure in neutral solution and cubic structure in an alkali solution with space group Pa3 and lattice parameter of 12.18 Å. The compound is the most important member of the generic class of compounds called alums, and is often called simply alum. Potassium alum is commonly used in water purification, leather tanning, dyeing, fireproof textiles, and baking powder as E number E522. It also has cosmetic uses as a deodorant, as an aftershave treatment and as a styptic for minor bleeding from shaving.
These included French pharmacist Alexandre Rouhier's Le Peyotl: La Plante Qui Fait les Yeux Émerveillés (Peyote: The Plant That Fills the Eyes with Marvels) in 1927, the German psychiatrist Kurt Beringer's Der Meskalinrausch, seine Geschichte und Erscheinungsweise (Mescaline Intoxication, its History and Manifestation) in 1927, and German–American psychologist Heinrich Klüver's Mescal: The Divine Plant and Its Psychological Effects in 1928. Studies of the potential therapeutic effects of mescaline started in the 1950s. It was studied as part of psychedelic-assisted psychotherapy by Walter Frederking by 1953. Aldous Huxley's book The Doors of Perception, about his experience with mescaline, was published in 1954. In 1955, English politician Christopher Mayhew took part in an experiment for BBC's Panorama, in which he ingested 400 mg of mescaline under the supervision of psychiatrist Humphry Osmond. Though the recording was deemed too controversial and ultimately omitted from the show, Mayhew praised the experience, calling it "the most interesting thing I ever did" and saying that it was "profoundly thought-provoking". The mechanism of action of mescaline, activation of the serotonin 5-HT2A receptors, became fully known in the 1990s. A serotonin 5-HT2A receptor antagonist, specifically ketanserin, was first clearly shown to block the psychedelic effects of mescaline in humans by Matthias Liechti and colleagues in 2024. The history of mescaline was reviewed in the 2019 book Mescaline: A Global History of the First Psychedelic by cultural historian Mike Jay.
Sources: en.wikipedia.org
它不是经典的内分泌激素，而是一种免疫调节肽。其作用主要通过局部免疫细胞间的信号传递实现，而非经血液循环作用于远隔器官。
天然胸腺素α1主要从胸腺组织提取，也可在脾脏和淋巴结中检出。目前研究和临床使用的多为化学合成版本，不再依赖动物组织。
胸腺素组分5是牛胸腺提取物的粗组分，包含多种肽。胸腺素α1是其中一种被纯化和表征的单一肽，具有明确的28个氨基酸序列。
It is usually described as an immunomodulatory peptide rather than a classic circulating hormone. No endocrine gland is known to release it as a primary secretory product, and its measured presence in blood is not firmly established.