A practical reference on Collapse temperature: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-12-24 and is reviewed periodically as new material appears.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and fixes the structure of the sample. After freezing, primary drying lowers pressure so ice changes directly to vapor without passing through a liquid phase. Secondary drying then removes bound water that remains after ice sublimation. The result is a dry, porous solid that often retains its original shape.
The low pressure used during drying allows water vapor to move from the ice surface to a cold condenser. Energy supplied as heat drives sublimation but must stay below the collapse temperature of the frozen matrix. If the product becomes too warm, the frozen structure may soften or melt, reducing pore formation and slowing drying. Formulations often include bulking agents, stabilizers, or buffers to support a rigid cake. The final moisture content depends on formulation, freezing rate, and the length of secondary drying.
Lyophilization is a drying process in which a solvent, usually water, is removed from a frozen material by sublimation under reduced pressure. The material is first solidified, then placed under vacuum so that ice transitions directly to vapor without a bulk liquid phase. This approach suits heat-sensitive substances that would degrade during conventional evaporation. Primary drying removes unbound ice, while secondary drying reduces water that remains adsorbed to the solid matrix. The result is a porous, lightweight solid that can be reconstituted later.
A typical cycle begins with freezing, sometimes including an annealing step to control ice crystal size. Freezing conditions influence the pore network that later allows vapor escape. During primary drying, shelf temperature and chamber pressure are set so heat enters the product while its temperature stays below the collapse or eutectic point. Secondary drying then raises the shelf temperature to desorb bound water and lower residual moisture. Cycle design depends on formulation, fill volume, container type, and equipment capability.
| Property | Value | Notes |
|---|---|---|
| Primary phase change | Sublimation | Ice changes directly to vapor under reduced pressure |
| Typical chamber pressure | 0.01–0.5 mbar (1–50 Pa) | Below the triple point of water; product-specific |
| Typical product temperature during primary drying | −40 °C to −10 °C | Kept below collapse temperature |
| Typical residual moisture | 0.5–3% w/w | Target range varies by formulation and use |
| Common synonyms | Freeze-drying; lyophilisation | Lyophilization is the US spelling |
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen to convert liquid water into ice. Next, the pressure is reduced below the triple point of water so that ice changes directly into vapor without passing through a liquid phase. This step is called primary drying. The result is a porous solid or cake that retains the original shape of the frozen solution.
After primary drying, secondary drying removes water that remains bound to the material. This stage raises the shelf temperature while maintaining low pressure, which encourages desorption of unfrozen water. Residual moisture can be reduced to a low percentage, improving stability for many products. The process parameters, including freezing rate, shelf temperature, and chamber pressure, influence the final pore structure and reconstitution behavior. Control of these variables helps prevent collapse or meltback during drying.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
Freezing determines ice crystal structure and pore size, which affect drying speed and product uniformity. Rapid freezing creates small crystals, while slow freezing creates larger crystals and often faster sublimation. During primary drying, chamber pressure is held below the vapor pressure of ice, and shelf temperature supplies heat for sublimation. The ice front recedes, leaving a porous matrix. Thermal limits such as collapse and eutectic temperatures set safe boundaries for formulation. These limits vary with solute composition and concentration.
=== Insulin glargine === Insulin glargine is a long-acting modified form of medical insulin used in the management of type 1 and type 2 diabetes. It is administered through subcutaneous injection. Its effects typically begin within an hour of injection. Common side effects include (hypoglycemia, issues at the injection site, itchiness, and weight gain. NPH insulin is generally preferred over insulin glargine during pregnancy. After injection, microcrystals gradually release insulin over a period of approximately 24 hours. This insulin works by facilitating the absorption of glucose by body tissues and reducing glucose production by the liver. Insulin glargine was patented, although the patent expired in most countries in 2014. It was approved for medical use in the United States in 2000. It is listed on the World Health Organization's List of Essential Medicines. In 2022, it ranked as the 28th most commonly prescribed medication in the United States, with more than 18 million prescriptions. In July 2021, the US Food and Drug Administration (FDA) approved an interchangeable biosimilar insulin product, Semglee (insulin glargine-yfgn), for the treatment of diabetes. Unbranded versions of insulin glargine and insulin glargine-yfgn are sold by Sanofi and Viatris.
==== Zwitterionic surfactants ==== Zwitterionic (ampholytic) surfactants have both cationic and anionic centers attached to the same molecule. The cationic part is based on primary, secondary, or tertiary amines or quaternary ammonium cations. The anionic part can be more variable and include sulfonates, as in the sultaines CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) and cocamidopropyl hydroxysultaine. Betaines such as cocamidopropyl betaine have a carboxylate with the ammonium. The most common biological zwitterionic surfactants have a phosphate anion with an amine or ammonium, such as the phospholipids phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine, and sphingomyelins. Lauryldimethylamine oxide and myristamine oxide are two commonly used zwitterionic surfactants of the tertiary amine oxides structural type.
There are also the testimonies of Raymond Queneau (1903–1976), born in Le Havre, the city served as a framework for his novel Un rude hiver (A harsh winter) (1939). The plot of Une maison soufflée aux vents (A house blown to the winds) by Émile Danoën, winner of the Popular Novel Prize in 1951, and its sequel Idylle dans un quartier muré (Idyll in a walled neighbourhood) were located in Le Havre during the Second World War. Under the name Port de Brume Le Havre is the setting for three other novels by this author: Cerfs-volants (Kites), L'Aventure de Noël (The Adventure at Christmas), and La Queue à la pègre (Queue to the underworld). Michel Leiris wrote De la littérature considérée comme une tauromachie (Of literature considered like a bullfight) in December 1945. Diana Gabaldon set the second novel in her Outlander series, Dragonfly in Amber (1992), partly in Le Havre. Two mystery novels take place in Le Havre: Le Bilan Maletras (The Maletras Balance) by Georges Simenon and Le Crime de Rouletabille (Crime at the Roulette table) by Gaston Leroux. In Rouge Brésil (Red Brazil), winner of the Goncourt Prize in 2001, Jean-Christophe Rufin describes Le Havre in the 16th century as the port of departure of French expeditions to the New World: the hero Villegagnon leaves of the port to conquer new lands for the French crown which become Brazil. Martine–Marie Muller tells the saga of a clan of Stevedores from Le Havre in the 1950s to the 1970s in Quai des Amériques (Quay of the Americas).
Sources: en.wikipedia.org
While chloral hydrate was converted to a different metabolite than chloroform, it was found that it was converted into the more lipophilic molecule 2,2,2-trichloroethanol. This metabolite fit much better with the Meyer–Overton correlation than chloral had. Prior to this, it had not been demonstrated that general anesthetics could undergo chemical changes to exert their action in the body. Chloral hydrate was the first hypnotic to be used intravenously as a general anesthetic. In 1871, Pierre-Cyprien Oré began experiments on animals, followed by humans. While a state of general anesthesia could be achieved, the technique never caught on because its administration was more complex and less safe than the oral administration of chloral hydrate, and less safe for intravenous use than later general anesthetics were found to be.
87Rb, 187Re, 176Lu, 232Th, and 238U have half-lives long enough that their decay is limited over geological time scales; 40K and 235U have shorter half-lives and are hence severely depleted, but are still long-lived enough to remain present in significant amount on Earth. The longest-lived isotope not proven to be primordial is 146Sm, which has a half-life of 9.20×107 years, followed by 244Pu (8.13×107 years) and 92Nb (3.47×107 years). 244Pu was reported to exist in nature as a primordial nuclide in 1971, but this detection could not be confirmed by further studies in 2012 and 2022. Taking into account that all these nuclides must exist for at least 4.58×109 years, 146Sm must survive 50 half-lives (and hence be reduced by 250 ≈ 1×1015), 244Pu must survive 57 (and be reduced by a factor of 257 ≈ 1×1017), and 92Nb must survive 130 (and be reduced by 2130 ≈ 1×1039). Mathematically, considering the likely initial abundances of these nuclides, primordial 146Sm and 244Pu should persist somewhere within the Earth today, even if they are not identifiable in the relatively minor portion of the Earth's crust available to human assays, while 92Nb and all shorter-lived nuclides should not. Nuclides such as 92Nb that were present in the primordial solar nebula but have long since decayed away completely are termed extinct radionuclides if they have no other means of being regenerated. As for 244Pu, calculations suggest that as of 2022, sensitivity limits were about one order of magnitude away from detecting it as a primordial nuclide.
Extraction of lithium, nickel, and cobalt, manufacture of solvents, and mining byproducts present significant environmental and health hazards. Lithium extraction can be fatal to aquatic life due to water pollution. It is known to cause surface water contamination, drinking water contamination, respiratory problems, ecosystem degradation and landscape damage. It also leads to unsustainable water consumption in arid regions (1.9 million liters per ton of lithium). Massive byproduct generation of lithium extraction also presents unsolved problems, such as large amounts of magnesium and lime waste. Lithium mining takes place in North and South America, Asia, South Africa, Australia, and China. Cobalt for Li-ion batteries is largely mined in the Congo (see also Mining industry of the Democratic Republic of the Congo). Open-pit cobalt mining has led to deforestation and habitat destruction in the Democratic Republic of Congo. Open-pit nickel mining has led to environmental degradation and pollution in developing countries such as the Philippines and Indonesia. In 2024, nickel mining and processing was one of the main causes of deforestation in Indonesia. Manufacturing a kg of Li-ion battery takes about 67 megajoules (MJ) of energy. The global warming potential of lithium-ion batteries manufacturing strongly depends on the energy source used in mining and manufacturing operations, and is difficult to estimate, but one 2019 study estimated 73 kg CO2e/kWh. Effective recycling can reduce the carbon footprint of the production significantly.
Sources: en.wikipedia.org
The two known blockers which are specific to P-type calcium channels are peptides derived from the spider venom of Agelenopsis aperta. The toxins from this venom which show selectivity for P-type channels are ω-agatoxin IVA and ω-agatoxin IVB. Each of these peptide toxins are made of 48 amino acids which are bound by four disulfide bonds. Although ω-agatoxin IVA and ω-agatoxin IVB have the same affinity and selectivity for P-type channels, their kinetics are different. The ω-agatoxin IVA effects the gating mechanism of the P-type channel. When there is a strong depolarization to activate the channel, ω-agatoxin IVA can no longer block the channel. Therefore, ω-agatoxin IVA has a very low affinity for the channel when it is open. It binds to the α1A subunit on the outside of the pore. The ω-agatoxin IVA receptor on the P-type channel is located at the S3-S4 linker. On the other hand, channel blocking by ω-agatoxin IVB occurs much more slowly. Yet, similar to ω-agatoxin IVA, ω-agatoxin IVB cannot bind to the channel upon a strong depolarization.
Electrical and pharmacological stimulation of the Vagus nerve increases secretion of glucagon and insulin in most mammalian species, including humans. This suggests that the role of parasympathetic control is to maintain normal blood glucose concentration under normal conditions.
== Ecological relevance == Numerous studies and published data comparing Microtox results with toxicity values for fish, crustaceans and algae have found a positive correlation. However, others have pointed out that the effect of luminosity on the survival of organisms is unknown. Concerns have also been expressed regarding the use of sediment extracts and not the sediment itself. It is possible that only water-soluble contaminants will be tested for, and therefore may not be representative of the full range of contaminants present in the sediment. Extracts may also remove contaminants that are not bioavailable. This could lead to an over or under estimation of contaminants and their biological effects.
Sources: en.wikipedia.org
Lyophilization relies on sublimation, so water moves from solid ice to vapor without becoming liquid. The material is frozen, pressure is reduced, and controlled heat is supplied. Vapor is captured on a cold condenser, leaving a dry porous solid.
The process has three main stages: freezing, primary drying, and secondary drying. Freezing sets the ice structure, primary drying removes free ice, and secondary drying removes bound water. Each stage uses specific temperature, pressure, and time settings.
No, it is a drying method rather than a sterilization method. Removing water can limit microbial growth, but it does not reliably kill microorganisms. Sterility must come from separate steps such as filtration, heat treatment, or aseptic processing.
Freezing only converts liquid to solid. Lyophilization adds vacuum and controlled warming so frozen solvent sublimes, leaving a dry porous solid. The two steps are related but not interchangeable.