The short version of collapse temperature fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-11-05 and is reviewed periodically as new material appears.
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.
Freeze-drying is distinct from simple evaporation and from spray drying. Evaporation removes water at temperatures above freezing, while spray drying rapidly dries droplets in a heated gas stream. Lyophilization avoids high temperatures, which can be useful for heat-sensitive materials such as proteins, vaccines, and some foods. The porous cake produced by sublimation dissolves or rehydrates more quickly than a dense dried mass. Not all materials tolerate freezing or the pH shifts that can occur as solutes concentrate during ice formation.
Lyophilization removes water by freezing a material and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intermediate liquid state. Because the material remains frozen during primary drying, the structure often stays porous. This porous matrix can rehydrate quickly when water is added back. The low pressure also allows vapor to leave the solid matrix without boiling.
A typical cycle begins with freezing, which fixes the material into a solid and determines ice crystal size. Primary drying then raises heat under vacuum so ice sublimes, often near or below the collapse temperature of the formulation. Secondary drying removes bound water that remains after ice is gone, usually by gently warming the product. Each stage balances heat input against pressure to avoid melting or structural damage. Temperature probes and pressure sensors guide the transition between stages.
| 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, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
The process relies on the phase diagram of water, where the triple point marks the conditions at which ice, liquid water, and vapor coexist. By maintaining pressure below this point, typically around 0.01 to 0.1 millibar, sublimation becomes the dominant mechanism. Formulations often include excipients such as sugars or polymers that act as lyoprotectants and bulking agents. These additives help preserve the structure of the active ingredient and prevent collapse during drying. The choice of excipient and freezing rate influences the final cake morphology and stability.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
Lyophilization, also called freeze-drying, removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts free water into ice and may also produce a glassy phase. Primary drying then lowers chamber pressure so ice sublimes directly to vapor without passing through a liquid stage. Secondary drying raises the temperature modestly to remove bound water. The result is a porous, dry solid that usually reconstitutes quickly. Each stage influences pore structure, residual moisture, and stability.
The physics of lyophilization depends on phase boundaries and heat and mass transfer. During primary drying, heat supplied to the product must equal the latent heat of sublimation, while water vapor moves through the drying cake to the condenser. If shelf temperature or pressure is set too high, the ice front can exceed the collapse temperature, causing meltback or pore collapse. If conditions are too cold, drying slows and costs rise. Formulation excipients, vial geometry, and freezing rate alter these limits.
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.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
Gavin Christopher Newsom (born October 10, 1967) is an American politician and businessman serving since 2019 as the 40th governor of California. A member of the Democratic Party, he served from 2011 to 2019 as the 49th lieutenant governor of California and from 2004 to 2011 as the 42nd mayor of San Francisco. Born and raised in San Francisco, Newsom graduated from Santa Clara University in 1989 with a Bachelor of Science in political science. Afterward, he founded the boutique winery PlumpJack Group in Oakville, California, with billionaire heir and family friend Gordon Getty as an investor. The company grew to manage 23 businesses, including wineries, restaurants, and hotels. Newsom began his political career in 1996, when San Francisco mayor Willie Brown appointed him to the city's Parking and Traffic Commission. Brown then appointed Newsom to fill a vacancy on the Board of Supervisors the next year and Newsom was first elected to the board in 1998. Newsom was elected mayor of San Francisco in 2003 and reelected in 2007. He was elected lieutenant governor of California in 2010 and reelected in 2014. As lieutenant governor, Newsom hosted The Gavin Newsom Show from 2012 to 2013 and in 2013 wrote the book Citizenville, which focuses on using digital tools for democratic change. Newsom was elected governor in 2018 and reelected in 2022. He faced criticism for his personal behavior and leadership style during the COVID-19 pandemic, which contributed to an unsuccessful recall effort in 2021.
== Uses == There are three main uses of ribosome profiling: identifying translated mRNA regions, observing how nascent peptides are folded, and measuring the amount of specific proteins that are synthesized.
On January 26, 2016, Kennedy launched a third bid for a Senate seat. In seeking to succeed the retiring Vitter, he faced more than 20 opponents. Vitter had announced his forthcoming retirement from the Senate in 2015 after losing a bid for governor to John Bel Edwards. Kennedy's senatorial campaign was endorsed by the U.S. Chamber of Commerce, the National Federation of Independent Business, the NRA Political Victory Fund, the National Right to Life Committee, the American Conservative Union, Vice President-elect Mike Pence and President-elect Donald Trump. Kennedy, who had supported Vitter for governor the previous year, won the jungle primary and faced Democrat Foster Campbell in a December 10 runoff election. President-elect Donald Trump—who had received Kennedy's support in the 2016 presidential election—campaigned for Kennedy the day before the runoff. Kennedy defeated Campbell by 536,204 votes (61%) to 347,813 (39%). He lost the most-populated parishes of Orleans and East Baton Rouge, in which he had been reared, but was a runaway winner in Campbell's home parish of Bossier.
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== History == The tanning effect of dihydroxyacetone (DHA) was discovered in the 1950s by Eva Wittgenstein at Cincinnati Children's Hospital, who observed that DHA used in an oral treatment stained the skin brown on contact. The first commercial DHA self-tanner, Man-Tan, appeared in 1959, followed by Coppertone's "QT" (Quick Tan) in 1960; both produced an orange-toned result that gave early self-tanners a poor reputation. Reformulated products and, from the late 1990s, automated spray-tan booths broadened the market.
lethal mutation Any mutation that results in the premature death of the organism carrying it. Recessive lethal mutations are fatal only to homozygotes, whereas dominant lethals are fatal even in heterozygotes.
Sanger's reagent proved effective at labelling the N-terminal amino group at one end of the polypeptide chain. He then partially hydrolysed the insulin into short peptides, either with hydrochloric acid or using an enzyme such as trypsin. The mixture of peptides was fractionated in two dimensions on a sheet of filter paper, first by electrophoresis in one dimension and then, perpendicular to that, by chromatography in the other. The different peptide fragments of insulin, detected with ninhydrin, moved to different positions on the paper, creating a distinct pattern that Sanger called "fingerprints". The peptide from the N-terminus could be recognised by the yellow colour imparted by the FDNB label and the identity of the labelled amino acid at the end of the peptide determined by complete acid hydrolysis and discovering which dinitrophenyl-amino acid was there. By repeating this type of procedure Sanger was able to determine the sequences of the many peptides generated using different methods for the initial partial hydrolysis. These could then be assembled into the longer sequences to deduce the complete structure of insulin. Finally, because the A and B chains are physiologically inactive without the three linking disulfide bonds (two interchain, one intrachain on A), Sanger and coworkers determined their assignments in 1955. Sanger's principal conclusion was that the two polypeptide chains of the protein insulin had precise amino acid sequences and, by extension, that every protein had a unique sequence.
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=== Cartel affiliates and street gangs === Smaller drug cartels and localized street gangs operate across Mexico. These gangs can control retail drug markets, extortion rackets, and serve as enforcers of cartels. In Ciudad Juárez, for example, La Línea, historically allied with the Juárez Cartel, and Los Mexicles, aligned with the Sinaloa Cartel, have been responsible for major spikes of violence, and both groups maintain ties to U.S.-based gangs. In Jalisco and Michoacán, the Jalisco New Generation Cartel has recently allied with gangs such as Los Viagras (a former autodefensa group), to fight for territory and run oil theft operations, despite the two groups having been bitter rivals throughout the 2010s. While cartels are sometimes portrayed as centralized, hierarchical organizations, they often function more as loose networks of cells and affiliates that can shift loyalties or rebrand over time. This structure can make them resilient, but it also fuels infighting and fragmentation, contributing to persistent and unpredictable violence even when leaders are captured. Even long-standing cartels have experienced prolonged, violent internal disputes, such as the Sinaloa Cartel infighting in the 2020s.
For example, the α decay of 239Pu to 235U can be used as an example of this procedure. with the assumption of a perfect purification time T0 then there will be a linear relationship between the in-growth of 235U and time elapsed since purification. There are, however, various instances where the correlation is not as clear. This strategy may not apply when the parent-daughter pair achieve secular equilibrium very rapidly or when the half-life of the daughter nuclide is significantly shorter than the time that has elapsed since purification of the nuclear material, e.g. 237Np/233Pa. Another possible complication is if in environmental samples, non-equivalent metal/ion transport for parents and daughter species may complicate or invalidate the use of chronometric measurements. Special age-dating relationships exist, including the commonly employed 234U/230Th and 241Pu/241Am chronometers. In special circumstances, parent-granddaughter relationships can be used to elucidate the age of nuclear materials when the material is intentionally made to look older through the addition of daughter nuclides. Chronometry is based on the concept that the composition of the nuclear material changes as samples are prepared and analyzed. This barrier can be substantial for species that decay quickly or whose daughter products put forth spectral interferences. The decay of 233U, for example, has a t1/2~1.6×105years which is rapid in comparison to many species and yield 229Th, which emits an α particle that is isoenergetic, having the same energy, as the parent.
== Transport == Fish is transported widely in ships, and by land and air, and much fish is traded internationally. It is traded live, fresh, frozen, cured and canned. Live, fresh and frozen fish need special care.
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.
Primary drying removes ice by sublimation under vacuum. Secondary drying removes water that is bound to the material, often by warming the product after most ice has left. Both stages occur below temperatures that would cause unwanted melting.