If you have been reading about Collapse temperature and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-09-30. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Equipment for lyophilization includes a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. A refrigeration system cools the shelves and condenser below the product's freezing point. Process monitoring often uses Pirani and capacitance manometers, thermocouples, and resistance sensors. Cycle development balances product quality with time and energy use. Some products are annealed during freezing to improve crystallization of bulking agents. Open questions remain about scaling cycles between laboratory, pilot, and production freeze-dryers.
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 couples heat transfer, mass transfer, and phase behavior. Sublimation requires a vapor pressure difference between the ice front and the chamber, and the dried layer adds resistance to vapor flow. Amorphous formulations are characterized by a glass transition temperature of the maximally freeze-concentrated solute, often denoted Tg'. Crystalline bulking agents can provide structure, while amorphous excipients stabilize labile components. Open questions remain about spatial heterogeneity, edge effects, and how laboratory cycles scale to production.
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 |
|---|---|---|
| Common synonyms | Freeze-drying; lyophilisation; cryodesiccation | Regional spelling and historical terms. |
| Primary drying pressure | 0.05-0.5 mbar (5-50 Pa) | Kept below the triple point of water; product-specific. |
| Shelf temperature range | -40 to +40 °C | Freezing, primary, and secondary stages use different set points. |
| Cycle duration | 12-72 hours | Depends on fill volume, formulation, and equipment. |
| Condenser temperature | -50 to -80 °C | Must remain below the product's ice temperature. |
Freezing is the first stage and sets the ice structure that later becomes the pore network. The formulation is cooled below its freezing point, often with a controlled ramp, and solutes concentrate as ice forms. Primary drying then lowers chamber pressure and supplies heat to sublime the ice. The product temperature must stay below its collapse or eutectic temperature to prevent structural loss. Secondary drying raises the temperature modestly to remove bound water and achieve a low residual moisture.
A freeze-dryer consists of a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. Vials, ampoules, or bulk trays hold the product during the cycle. The condenser traps water vapor as ice at a temperature lower than the product. Cycle development balances shelf temperature, chamber pressure, and time. Scale-up can be difficult because heat and mass transfer change with equipment size, so process analytical tools and conservative validation are often used.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
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 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.
According to the online portal Box Office Mojo and the review aggregate site Rotten Tomatoes, DiCaprio's most critically and commercially successful films include What's Eating Gilbert Grape (1993), Romeo + Juliet (1996), Titanic (1997), Catch Me If You Can (2002), Gangs of New York (2002), The Aviator (2004), The Departed (2006), Blood Diamond (2006), Revolutionary Road (2008), Shutter Island (2010), Inception (2010), Django Unchained (2012), The Great Gatsby (2013), The Wolf of Wall Street (2013), The Revenant (2015), Once Upon a Time in Hollywood (2019), Don't Look Up (2021), Killers of the Flower Moon (2023), and One Battle After Another (2025). His films have grossed $7.2 billion worldwide. DiCaprio has been recognized with seven nominations, including one win, by the Academy of Motion Picture Arts and Sciences for the following:
=== Electronic cross-matching === Electronic cross-matching is a computer-assisted analysis using data, from the donor unit (where a donor's blood is tested prior to donation) and testing done on blood samples from the intended recipient. This includes ABO/Rh typing of the unit and of the recipient, and an antibody screen of the recipient. Electronic cross-matching can only be used if a patient has a negative antibody screen, which means that they do not have any active red blood cell atypical antibodies, or they are below the detectable level of current testing methods. If all of the data entered is compatible, the computer will print a compatibility label stating that the unit is safe to transfuse.
In mass spectrometry, fragmentation is the dissociation of energetically unstable molecular ions formed from passing the molecules mass spectrum. These reactions are well documented over the decades and fragmentation patterns are useful to determine the molar weight and structural information of unknown molecules. Fragmentation that occurs in tandem mass spectrometry experiments has been a recent focus of research, because this data helps facilitate the identification of molecules.
== Impact on settlement patterns in the United States of America == The development of refrigerated transportation changed the geography of food production and distribution in the United States by allowing perishable agricultural products to be transported over greater distances. This contributed to the development of agricultural regions farther from major eastern markets and established transport routes.
=== Freeze drying === Freeze drying is accomplished by lowering the pressure in a chamber containing the wood to a few millibars, while lowering the temperature of the chamber to below the eutectic point of the material. Heat is typically added slowly to the material to allow the water contained in the wood to sublimate directly into vapor, and be deposited on the sides of the vacuum chamber or in the cold trap through which the chamber is evacuated. Freeze drying through sublimation typically takes about 10 times the energy that is taken through evaporation of water by heat. In practice, freeze drying of wood can be accomplished by placing room temperature wood in a vacuum chamber that can be chilled to -30 degrees C or lower, evacuating the chamber to a few millibars, and at the same time cooling the chamber to a freezing temperature. The latent heat of the ice in the wood will come out through the water vapor, which will condense as ice on the inside of the chamber. After a few hours under vacuum and freezing conditions, the chamber is returned to normal pressure, the wood removed and bagged in plastic to keep water from condensing on it, and allowed to return to room temperature over a few hours to a day. The cycle is then repeated, each time the latent heat in the wood is removed through the water content in the wood sublimating and/or evaporating and condensing on the sides of the container and in the cold trap. The cycles are repeated until the moisture content of the wood is at a pre-determined acceptable level.
Sources: en.wikipedia.org
South Africa claimed 152 security-related incidents involving PLAN occurred in South West Africa that year, and acknowledged the combat deaths of 77 SADF and SWATF personnel. In July 1983 PLAN carried out its first major act of urban sabotage, detonating a bomb in the centre of Windhoek, which caused extensive property damage but no civilian injuries. Infiltration of Ovamboland and Kavangoland increased dramatically at around the same time, with 700 insurgents entering both regions. The SADF claimed to have killed or captured just under half the insurgents by May, but was unable to prevent the others from making their way further south. These developments indicated that PLAN had not lost its will to persevere despite the enormous materiel losses sustained during Protea, and the infiltration of men and supplies into South West Africa continued apace. Their confidence buoyed by the previous successful incursions into FAPLA-held territory, which had achieved marked success at only minimal cost in lives and materiel, Botha and his defence chiefs scheduled Operation Askari for December 1983. Like Protea, Askari was a major combined arms assault on PLAN base areas and supply lines in Angola; it also targeted nearby FAPLA air-defence installations and brigade headquarters. According to General Georg Meiring, commander of the SADF in South West Africa, Askari would serve the purpose of a preemptive strike aimed at eliminating the large numbers of PLAN insurgents and stockpiles of weapons being amassed for the annual rainy season infiltration.
Vaccinations given to children, adolescents, or adults are generally safe. Adverse effects, if any, are generally mild. The rate of side effects depends on the vaccine in question. Some common side effects include fever, pain around the injection site, and muscle aches. Additionally, some individuals may be allergic to ingredients in the vaccine. The MMR vaccine is rarely associated with febrile seizures. Host-("vaccinee")-related determinants that render a person susceptible to infection, such as genetics, health status (underlying disease, nutrition, pregnancy, sensitivities or allergies), immune competence, age, and economic impact or cultural environment can be primary or secondary factors affecting the severity of infection and response to a vaccine. Elderly (above age 60), allergen-hypersensitive, and obese people have susceptibility to compromised immunogenicity, which prevents or inhibits vaccine effectiveness, possibly requiring separate vaccine technologies for these specific populations or repetitive booster vaccinations to limit virus transmission. Severe side effects are extremely rare. Varicella vaccine is rarely associated with complications in immunodeficient individuals, and rotavirus vaccines are moderately associated with intussusception. At least 19 countries have no-fault compensation programs to provide compensation for those with severe adverse effects of vaccination. The United States' program is known as the National Childhood Vaccine Injury Act, and the United Kingdom employs the Vaccine Damage Payment.
==== Extracellular phenoloxidases ==== Phenols are an important group of ecotoxins due to their toxicity and persistence. Many microorganisms can degrade aromatic pollutants and use them as a source of energy, and the ability of microalgae to degrade a multitude of aromatic compounds including phenolic compounds is increasingly recognized. Some microalgae including Chlamydomonas sp., Chlorella sp., Scenedesmus sp. and Anabaena sp. are able to degrade various phenols such as pentachlorophenol, p-nitrophenol, and naphthalenesulfonic acids. Though the metabolic degradation pathways are not fully understood, enzymes including phenoloxidase laccase (EC 1.10.3.2) and laccase-like enzymes are involved in the oxidation of aromatic substrates. These exoenzymes can be potentially applied in the environmental degradation of phenolic pollutants.
== Retirement == Meurgues retired to Saint-Germain-de-Modéon, continuing to write articles in specialist magazines, sharing her knowledge in museology and scriptwriting, as well as restoring the family farm and creating an animal rescue refuge. She donated her scientific library to the Muséum d'Autun and is preparing a book Inventions et bricolages de la nature. She published Du jardin de Buffon à l'Afghanistan: mémoires d'une naturaliste in 2019. Geneviève Meurgues died on 21 December 2021, in her 91st year. According to her last wishes, her cremation was private and her ashes will be spread in the "Les Grands Bouchons" wood, where her vocation as a naturalist was born.
Sources: en.wikipedia.org
Severe renal impairment (estimated glomerular filtration rate (eGFR) below 30 mL/min/1.73 m2) Known hypersensitivity to metformin Acute or chronic metabolic acidosis, including diabetic ketoacidosis (from uncontrolled diabetes), with or without coma
The use of fermentation, particularly for beverages, has existed since the Neolithic and has been documented dating from 7000 to 6600 BCE in Jiahu, China, 6000 BCE in Georgia, 3150 BCE in ancient Egypt, 3000 BCE in Babylon, 2000 BCE in pre-Hispanic Mexico, and 1500 BC in Sudan. Fermented foods have a religious significance in Judaism and Christianity. The Baltic god Rugutis was worshiped as the agent of fermentation.
Listed below are the athletes who have achieved a 1,000 pounds (453.6 kilograms) or more deadlift, a feat which has been accomplished by only 40 men in history. It includes both strongman and powerlifting deadlifts performed using only the conventional stance. Sanctioned lifts during competitions and exhibitions, as well as unsanctioned lifts during training (with video proof) are included.
==== Organorhodium compounds ==== Rhodium is known for its many organometallic derivatives. Rhodium(I) complexes are commonly used as catalysis, with a few being BINAP-Rh(I), DIPAMP-Rh(I), and BDPP-Rh(I). Cyclopentadienyl complexes of rhodium have been investigated as analogues of ferrocene. The parent is rhodocene, which participates in an unusual monomer-dimer equilibrium: Related cyclopentadienyl compounds include the Rh(I) and Rh(III) half-sandwich complexes (C5H5)Rh(CO)2 and Pentamethylcyclopentadienyl rhodium dichloride dimer (C5(CH3)5RhCl2)2. The latter compound is prepared by the reaction of rhodium trichloride trihydrate and pentamethylcyclopentadiene in hot methanol. A related but cationic family of hydrogenation catalysts arise from cyclooctadiene rhodium chloride dimer, Rh2Cl2(C8H12)2. The cyclooctadiene (C8H12) ligands are easily displaced, and this allows the easy introduction of chiral ligands, leading to asymmetric hydrogenations, including the Nobel Prize-winning route to the chiral drug L-DOPA. When treated with sodium borohydride and carbon monoxide, RhCl(P(C6H5)3)3 converts to the pentacoordinate complex RhH(CO)(P(C6H5)3)3, which is used commercially for the hydroformylation of alkenes. Despite its much higher cost, tris(triphenylphosphine)rhodium carbonyl hydride has displaced cheaper cobalt-based catalysts for this application.
However the quality and yield of these varieties are poor as compared to non-resistant strains and only Consort is reliably self-fertile. Back-crossing these varieties to a parent have produced new strains such as 'Titania' that have a higher yield, better disease resistance, are more tolerant of adverse weather conditions and are suitable for machine harvesting. Two new releases from a black currant breeding program in British Columbia, Canada, 'Blackcomb' and 'Tahsis', were selected for their immunity to white pine blister rust and their frost tolerance.
Sources: en.wikipedia.org
Simple drying usually removes water by evaporation from a liquid or solid, often with heat. Lyophilization first freezes the material and then removes ice by sublimation under vacuum. This avoids prolonged exposure to liquid water and high temperatures.
Reduced pressure lowers the boiling point of water and allows ice to sublime at temperatures below freezing. It also helps remove water vapor from the product toward the condenser. The exact pressure is chosen to stay below the triple point of water.
No. Materials with low solids content or high volatile solvents may form weak or collapsed cakes. Some proteins and cells require stabilizers to survive freezing and drying stresses. Feasibility depends on formulation and process design.
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.