Everything below concerns Collapse temperature. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilisation is the British spelling; the process is not simple evaporation. |
| Primary drying pressure | 0.05–0.3 mbar | Pressure must remain below the vapor pressure of ice at the product temperature. |
| Sublimation temperature | Below 0 °C | Ice changes directly to vapor while the product remains frozen. |
| Typical shelf temperature | −40 to −10 °C | Exact setting depends on formulation critical temperature and equipment. |
| Cycle duration | 12–72 hours | Time varies with fill volume, formulation, and dryer performance. |
A formulation often contains excipients that protect the active ingredient during freezing and drying. Bulking agents provide structure, while lyoprotectants stabilize sensitive molecules. The freezing step can produce ice crystals whose size and distribution affect the drying rate, and cycle design includes freezing, annealing, and drying phases. If the product temperature rises above a critical value, the cake may collapse or lose its porous structure. Successful lyophilization therefore depends on the interaction between formulation, equipment, and cycle design.
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.
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.
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.
In practice, lyophilization is slower and more energy intensive than simple drying. Cycle times can range from hours to several days depending on load, container, and formulation. Amorphous materials may require excipients that help preserve structure during freezing and drying. The method is widely used for biological materials, pharmaceuticals, and foods where heat drying would cause unacceptable change. Open questions remain about scaling cycles between laboratory and production equipment, and this gap affects technology transfer.
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.
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 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.
Kava is conspecific with Piper wichmannii, indicating kava was domesticated from Piper wichmannii (syn. Piper subbullatum). Kava was spread by the Austronesian Lapita culture after contact eastward into the rest of Polynesia. It is endemic to Oceania and is not found in other Austronesian groups. Kava reached Hawaii, but it is absent in New Zealand, where it cannot grow. Consumption of kava is also believed to be the reason why betel nut chewing, ubiquitous elsewhere, was lost for Austronesians in Oceania. According to Lynch (2002), the reconstructed Proto-Polynesian term for the plant, *kava, was derived from the Proto-Oceanic term *kawaR in the sense of a "bitter root" or "potent root [used as fish poison]". It may have been related to reconstructed *wakaR (in Proto-Oceanic and Proto-Malayo-Polynesian) via metathesis. It originally referred to Zingiber zerumbet, used to make a similar mildly psychoactive bitter drink in Austronesian rituals. Cognates for *kava include Pohnpeian sa-kau; Tongan, Niue, Rapa Nui, Tuamotuan, and Rarotongan kava; Samoan, Tahitian, and Marquesan ʻava; and Hawaiian ʻawa. In some languages, most notably Māori kawa, the cognates have come to mean "bitter", "sour", or "acrid" to the taste. In the Cook Islands, the reduplicated forms of kawakawa or kavakava are also applied to the unrelated members of the genus Pittosporum. In other languages, such as Futunan, compound terms like kavakava atua refer to other species belonging to the genus Piper. The reduplication of the base form is indicative of falsehood or likeness, in the sense of "false kava".
Duterte considers his close friend, pastor Apollo Quiboloy of the Kingdom of Jesus Christ (KJC), as his spiritual adviser. Duterte would become estate administrator of the properties KJC in March 2024, following Senate inquiries launched against the church and Quiboloy. In his post-presidency in January 2024, Duterte visited the wake of CBCP president Fernando Capalla in Davao Cathedral, during which he stated he attends Masses thrice every Sunday; he further added "I am a very holy man. I'm a whole human being now".
=== AP Care Homes === Pickston is the Director of AP Care Homes, a company based in the North West of England which provided residential care for children. The home catered for the needs of children aged 12-16 with emotional and behavioural difficulties. It was a long term solution for vulnerable children. It employed a registered manager, deputy manager and seven full time key workers. Following an inspection on 16 and 17 November 2023, Ofsted concluded AP Care Homes Limited had "serious and/or widespread failures that mean children and young people are not protected or their welfare is not promoted or safeguarded and the care and experiences of children and young people are poor and they are not making progress". Ofsted inspectors said that Pickston had overseen the management of the home but "did not have the skills and experience" to run it in line with children's home regulations. It was also found that Pickston took one child to her home and, after an internal investigation found that “professional boundaries had been blurred”, she allegedly offered to do it again three weeks later. The home closed in December 2023 after Ofsted issued a notice suspending the registration of the home.
=== Blood clots === Whereas the combination of estrogen and a progestin is associated with increased risk of venous thromboembolism (VTE) relative to estrogen alone, there is no difference in risk of VTE with the combination of estrogen and oral progesterone relative to estrogen alone. Hence, in contrast to progestins, oral progesterone added to estrogen does not appear to increase coagulation or VTE risk. The reason for the differences between progesterone and progestins in terms of VTE risk are unclear. However, they may be due to very low progesterone levels and relatively weak progestogenic effects produced by oral progesterone. In contrast to oral progesterone, non-oral progesterone—which can achieve much higher progesterone levels—has not been assessed in terms of VTE risk.
Sources: en.wikipedia.org
== Clinical significance == Patients with mutations in the GSS gene develop glutathione synthetase (GSS) deficiency, an autosomal recessive disorder. Patients develop a wide range of symptoms depending on the severity of the mutations. Mildly affected patients experience a compensated haemolytic anaemia because mutations affect stability of the enzyme. Moderately and severely affected individuals have enzymes with dysfunctional catalytic sites, rendering it unable to participate in detoxification reactions. Physiological symptoms include metabolic acidosis, neurological defects, and increased susceptibility to pathogenic infections. Treatment of individuals with glutathione synthetase deficiency generally involve therapeutic treatments to address mild to severe symptoms and conditions. In order to treat metabolic acidosis, severely affected patients are given large amounts of bicarbonate and antioxidants such as vitamin E and vitamin C. In mild cases, ascorbate and N-acetylcysteine have been shown to increase glutathione levels and increase erythrocyte production. Bbecause glutathione synthetase deficiency is so rare, it is poorly understood. The disease also appears on a spectrum, so it is even more difficult to generalize among the few cases that occur.
==== MeSH E05.200.875 – microbiological techniques ==== MeSH E05.200.875.150 – bacteriological techniques MeSH E05.200.875.150.125 – bacterial typing techniques MeSH E05.200.875.150.125.150 – bacteriophage typing MeSH E05.200.875.150.125.765 – ribotyping MeSH E05.200.875.150.125.890 – serotyping MeSH E05.200.875.150.570 – limulus test MeSH E05.200.875.220 – colony count, microbial MeSH E05.200.875.595 – microbial sensitivity tests MeSH E05.200.875.595.800 – serum bactericidal test MeSH E05.200.875.610 – mycological typing techniques MeSH E05.200.875.837 – serial passage MeSH E05.200.875.950 – viral load MeSH E05.200.875.970 – virus cultivation MeSH E05.200.875.970.790 – plaque assay MeSH E05.200.875.977 – virus inactivation MeSH E05.200.875.985 – xenodiagnosis
=== Research profile and funding === Arizona is classified among "R1: Doctoral Universities – Very high research activity". The University of Arizona achieved $1.012 billion in research expenditures for fiscal year 2024, ranking 19th among public universities nationwide. The University of Arizona is the fourth most awarded public university by NASA for research. UA students have been selected as Truman, Rhodes, Goldwater, and Fulbright Scholars. According to The Chronicle of Higher Education, UA is among the top 25 producers of Fulbright awards in the U.S. UA is a member of the Association of Universities for Research in Astronomy, a consortium of institutions pursuing research in astronomy. The association operates observatories and telescopes, notably Kitt Peak National Observatory just outside Tucson. UA is a member of the Association of American Universities.
overdose) with sympathomimetics, for instance caused by amphetamine, methamphetamine, cocaine, or ephedrine. It has also specifically been found to block the sympathomimetic effects of MDMA. Dual α1 and beta blockers like carvedilol and labetalol may be more favorable for such purposes due to the possibility of "unopposed α-stimulation" with selective beta blockers.
Its beneficial effects are also questionable, since the increased bone density is partially caused by the increased density of strontium over the calcium which it replaces. Strontium also bioaccumulates in the body. Despite restrictions on strontium ranelate, strontium is still contained in some supplements. There is not much scientific evidence on risks of strontium chloride when taken by mouth. Those with a personal or family history of blood clotting disorders are advised to avoid strontium. Strontium has been shown to inhibit sensory irritation when applied topically to the skin. Topically applied, strontium has been shown to accelerate the recovery rate of the epidermal permeability barrier (skin barrier).
Sources: en.wikipedia.org
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.
Freezing determines ice crystal size, solute distribution, and the pore network left after drying. A slow or fast freezing rate can produce different cake structures and affect reconstitution. It also sets whether the formulation follows an amorphous or crystalline drying path.
It removes most free water during primary drying and part of the bound water during secondary drying. A small residual moisture content often remains and is specified for each product. Complete removal is generally neither practical nor desirable for stability.
Yes. Lyophilization and freeze-drying are synonyms for the same vacuum-assisted sublimation process. The term lyophilization is more common in pharmaceutical and laboratory settings, while freeze-drying is widely used in food and general contexts.