The short version of lyophilization fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-08-27. Anything still debated is marked as such rather than presented as settled.
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 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 |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilization is the American spelling; lyophilisation is British |
| Primary drying mechanism | Sublimation of ice | Occurs under vacuum below the triple point |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product and equipment |
| Typical shelf temperature during freezing | -40 to -20 °C | Lower temperatures may be used for labile products |
| Resulting product form | Porous cake or powder | Appearance depends on formulation and cycle |
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.
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.
The membership of the PSC was reduced from nine to seven, with Xi and Li Keqiang retaining their seats; the other five members were new. In December 2012, Xi visited Guangdong in his first trip outside Beijing since taking the general secretaryship. The overarching theme of the trip was to call for further economic reform and a strengthened military. Xi was elected president on 14 March 2013, in a confirmation vote during the first session of the 12th National People's Congress in Beijing. He received 2,952 for, one vote against, and three abstentions. He replaced Hu Jintao, who retired after serving two terms. Xi was also elected as the chairman of the state CMC. He subsequently nominated Li Keqiang to be the premier, who was then appointed by the NPC.
Previously, there had been no detailed descriptions of their spectral properties in peer-reviewed general scientific literature. A small amount of agent A-230 was also claimed to have been synthesised in the Czech Republic in 2017 for the purpose of obtaining analytical data to help defend against these novel toxic compounds. The Soviet Union and Russia reportedly developed extremely potent fourth-generation chemical weapons from the 1970s until the early 1990s, according to a publication by two chemists, Lev Fyodorov and Vil Mirzayanov, in Moskovskiye Novosti weekly in 1992. The publication appeared just on the eve of Russia's signing of the Chemical Weapons Convention. According to Mirzayanov, the Russian Military Chemical Complex (MCC) was using defence conversion money received from the West for development of a chemical warfare facility. Mirzayanov made his disclosure out of environmental concerns. He was the head of a counter-intelligence department and performed measurements outside the chemical weapons facilities to make sure that foreign spies could not detect any traces of production. To his horror, the levels of deadly substances were eighty times greater than the maximum safe concentration. The Prosecutor-General of Russia effectively admitted the existence of Novichok agents when he brought a treason case against Mirzayanov. According to expert witness testimonies that three scientists prepared for the KGB, Novichok and other related chemical agents had indeed been produced and therefore Mirzayanov's disclosure represented high treason.
== History == 4-HO-DPT was first described in the scientific literature by David Repke and colleagues in 1977. Subsequently, it was described in further detail by Alexander Shulgin in his 1997 book TiHKAL (Tryptamines I Have Known and Loved). The drug was encountered as a novel designer drug in Europe in 2012.
Sources: en.wikipedia.org
== Diagnosis == Skin changes, abnormal growth, and loss of hair occur. These symptoms normally start appearing by one year of age. A genetic test for LMNA mutations can confirm the diagnosis of progeria. Prior to the advent of the genetic test, misdiagnosis was common.
Pirbuterol (trade name Maxair) is a short-acting β2 adrenoreceptor agonist with bronchodilating action used in the treatment of asthma, available (as pirbuterol acetate) as a breath-activated metered-dose inhaler. It was patented in 1971 and came into medical use in 1983.
=== Procedure in the United States === In the United States, the typical lethal injection begins with the condemned person being strapped onto a gurney; two IV cannulas are then inserted, one in each arm. Only one is necessary to carry out the execution; the other is reserved as a backup in the event the primary line fails. A line leading from the IV line in an adjacent room is attached to the prisoner's IV and secured so that the line does not snap during the injections. The arm of the condemned person is swabbed with alcohol before the cannula is inserted. The needles and equipment used are sterilized. Although the person is not expected to survive the injection, there are nonetheless reasons to use measures against infection. First, sterile equipment is mass-produced and readily available from medical suppliers. Secondly, the prisoner could receive a stay of execution after the cannulae have been inserted, as in the case of James Autry in October 1983. Third, the use of unsterilized equipment would be a hazard to the prison personnel in case of an accidental needle stick injury. Following the connection of the lines, saline drips are started in both arms. This, too, is standard medical procedure: it must be ascertained that the IV lines are clear, ensuring the chemicals have not precipitated in them and blocked the needle, preventing the drugs from reaching the subject. A heart monitor is attached to the inmate.
Sources: en.wikipedia.org
Before the arrival of viticulture, Ningxia's 6.8 million people, 36 per cent of whom are Muslims from the Hui ethnic group, relied largely on animal grazing, subsistence agriculture and the cultivation of wolfberries used in traditional Chinese medicine. Since then, winemaking has become the premier specialty of Ningxia, and the province devotes almost 40,000 hectares to vineyards and producing 120 million bottles of wine in 2017 – a quarter of the entire nation's production.
By using QDs, only the necessary colors for ideal images are contained in the screen. The first commercial application of quantum dots was the Sony XBR X900A series of flat panel televisions released in 2013. In June 2006, QD Vision announced technical success in making a proof-of-concept quantum dot display and show a bright emission in the visible and near infrared region of the spectrum. A QD-LED integrated at a scanning microscopy tip was used to demonstrate fluorescence near-field scanning optical microscopy (NSOM) imaging.
== Research examples == In 2012 research was published where genes and proteins were found in a model organism that could not have been found without GFS because they had not been previously annotated. The planarian Schmidtea mediterranea has been used in research for over 100 years. This planarian is capable of regenerating missing body parts and is therefore emerging as potential model organism for stem cell research. Planarians are covered in mucus which aids in locomotion, in protecting them from predation, and in helping their immune system. The genome of Schmidtea mediterranea is sequenced but mostly un-annotated making it a prime candidate for genome-based peptide fingerprint scanning. When the proteins were analyzed with GFS 1,604 proteins were identified. These proteins had mostly not been annotated before they were found with GFS They were also able to find the mucous subproteome (all the genes associated with mucus production). They found that this proteome was conserved in the sister species Schmidtea mansoni. The mucous subproteome is so conserved that 119 orthologs of planarians are found in humans. Due to the similarity in these genes the planarian can now be used as a model to study mucous protein function in humans. This is relevant for infections and diseases related to mucous aberrancies such as cystic fibrosis, asthma, and other lung diseases. These genes could not have been found without GFS because they had not been previously annotated.
Sources: en.wikipedia.org
Lyophilization removes water by sublimation from a frozen material, while evaporation changes liquid water into vapor. The low-pressure freezing step avoids the liquid phase and can preserve heat-sensitive structures.
Vacuum lowers the pressure below the triple point of water, allowing ice to sublimate directly into vapor. It also helps remove water vapor from the product chamber and shortens primary drying.
Many aqueous solutions and suspensions can be freeze-dried, but some formulations collapse or do not form a stable cake. The process requires careful formulation and cycle development.
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.