Everything below concerns Lyophilization. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-08-08. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Lyophilization is a dehydration technique in which a product is frozen and the solvent is removed under reduced pressure. The low pressure allows ice to sublimate directly into vapor without passing through a bulk liquid phase. This differs from conventional drying, where heat drives evaporation and can damage heat-sensitive structures. The process is used for biological materials, pharmaceutical formulations, and some foods. Its main advantage is preservation of porous structure and rapid reconstitution.
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, cryodesiccation | Lyophilization is common in pharmaceutical literature. |
| Typical chamber pressure during primary drying | 0.05–0.5 mbar (5–50 Pa) | Must remain below the triple point of water. |
| Typical shelf temperature during freezing | −40 to −20 °C | Lower temperatures may be used for eutectic systems. |
| Typical residual moisture after secondary drying | 0.5–3% w/w | Product-dependent; low moisture improves stability but can cause over-drying. |
| Typical analytical method for residual moisture | Karl Fischer titration or loss on drying | Thermogravimetric methods are also used. |
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.
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.
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.
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.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
=== Biosynthesis === Met-enkephalin is synthesized from proenkephalin via proteolytic cleavage in two metabolic steps. Proenkephalin A is first reduced by either one of two trypsin-like endopeptidase enzymes, proprotein convertase 1 (PC1) or prohormone convertase 2 (PC2); then, the resulting intermediates are further reduced by the enzyme carboxypeptidase E (CPE; previously known as enkephalin convertase (EC)). Proenkephalin A contains four sequences of met-enkephalin (at the following positions: 100–104; 107–111; 136–140; 210–214), and as a result, its cleavage generates four copies of met-enkephalin peptides at once. In addition, anabolism of proenkephalin A results in the production of one copy each of two C-terminal-extended met-enkephalin derivatives, the heptapeptide met-enkephalin-arg-phe (261–267), and the octapeptide met-enkephalin-arg-gly-leu (186–193), though whether they affect the opioid receptors in a similar manner as met-enkephalin is not entirely clear.
=== Media === In France, the French syndicate of non-alcoholic beverages "Boissons Rafraîchissantes de France" (that included soft drink producers such as Coca-Cola France, Orangina, PepsiCo France) was denounced by the French journal fr:Canard Enchainé for misleading consumers using a communication on their website titled "Better understanding the NASH pathology", explaining that "NASH pathology is sometimes called the soda illness by language abuse or an unfortunate semantic shortcut, as it is not directly linked to the consumption of non-alcoholic beverages". This page and others on the same website, such as one titled "Say no to disinformation," were removed since then.
=== Priapism === A relatively rare side effect associated with trazodone is priapism, likely due to its antagonism at α-adrenergic receptors. More than 200 cases have been reported, and the manufacturer estimated that the incidence of any abnormal erectile function is about one in 6,000 male patients treated with trazodone. The risk for this side effect appears to be greatest during the first month of treatment at low dosages (i.e. <150 mg/day). Early recognition of any abnormal erectile function is important, including prolonged or inappropriate erections, and should prompt discontinuation of trazodone treatment. Spontaneous orgasms have also been reported with trazodone in men. Clinical reports have described trazodone-associated psychosexual side effects in women as well, including increased libido, priapism of the clitoris, and spontaneous orgasms.
=== Levinthal's paradox === In 1969, Cyrus Levinthal noted that, because of the very large number of degrees of freedom in an unfolded polypeptide chain, the molecule has an astronomical number of possible conformations. An estimate of 3300 or 10143 was made in one of his papers. Levinthal's paradox is a thought experiment based on the observation that if a protein were folded by sequential sampling of all possible conformations, it would take an astronomical amount of time to do so, even if the conformations were sampled at a rapid rate (on the nanosecond or picosecond scale). Based upon the observation that proteins fold much faster than this, Levinthal then proposed that a random conformational search does not occur, and the protein must, therefore, fold through a series of meta-stable intermediate states.
7-Eleven has been established in Norway since 13 September 1986, when the first store opened in Oslo. In 2004, Reitan Convenience, a branch of the Norwegian Reitan Group bought the rights to use the 7-Eleven brand in Norway, Sweden and Denmark and since then has massively grown the number of operating shops in Scandinavia.
Sources: en.wikipedia.org
The final allocation of output was achieved through relatively decentralized, unplanned contracting. Although in theory prices were legally set from above, in practice they were often negotiated, and informal horizontal links (e.g. between producer factories) were widespread. A number of basic services were state-funded, such as education and health care. In the manufacturing sector, heavy industry and defence were prioritized over consumer goods. Consumer goods, particularly outside large cities, were often scarce, of poor quality and limited variety. Under the command economy, consumers had almost no influence on production, and the changing demands of a population with growing incomes could not be satisfied by supplies at rigidly fixed prices. A massive unplanned second economy grew up at low levels alongside the planned one, providing some of the goods and services that the planners could not. The legalization of some elements of the decentralized economy was attempted with the reform of 1965.
== Institutions with hypobaric chambers == terraXcube, Eurac Research, accredited laboratory for environmental testing with large climatic chambers and medical clinic Centro de Medicina Aeroespacial de la Fuerza Aerea Colombiana, Aviation medicine, physiological, and hypobaric services Royal New Zealand Air Force Aviation Medicine Unit , Aviation medicine training and hypobaric services U.S. Army Institute of Environmental Medicine, Natick, MA, 33 years experience with its Hypobaric Chamber Facility Sheppard Air Force Base in Wichita Falls, Texas University of North Dakota's John D. Odegard School of Aerospace Sciences, Aviation Training Naval Operational Medicine Institute, Operational medical and survival training and consultative services to military forces worldwide Arizona State University Polytechnic Campus, Aircrew training, research, and other uses National AeroSpace Training And Research (NASTAR) Center South, Air and space training, research, and education RAF Centre of Aviation Medicine Center for Man in Aviation, Royal Netherlands Air Force, Aircrew training, physiology, research and certification of equipment University Hospitals Cleveland Medical Center in Cleveland, Ohio, aerospace physiology research AXA Training Center, Training ground of Liverpool F.C.
=== OpenTag === DASH7 Mode 2 developers benefit from the open-source firmware library called OpenTag, which provides developers with a "C"-based environment in which to develop DASH7 applications quickly. So in addition to DASH7 (ISO 18000-7) being an open source, ISO standard, OpenTag is an open-source stack that is quite unlike other wireless sensor networking (e.g. ZigBee) and active RFID (e.g. proprietary) options elsewhere in the marketplace today. Even though OpenTag is an open-source project, people may not be able to use it free of charge. As of August 2015, there is no evidence to suggest that OpenTag bears a royalty, although current versions of OpenTag license Archived 2013-12-31 at the Wayback Machine do include a provision permitting RAND licensing.
Organized crime groups also do a range of business and labor racketeering activities, such as skimming casinos, insider trading, setting up monopolies in industries such as garbage collecting, construction and cement pouring, bid rigging, getting "no-show" and "no-work" jobs, political corruption and bullying.
Sources: en.wikipedia.org
=== Chipper teeth === Chipper chain invented by Joseph Cox improved dramatically on the performance of scratcher chain. Chipper used a tooth that was curled over the top of the chain, with alternate teeth pointing left and right. Ahead of the tooth was a depth gauge, which allowed for good clearance around the tooth for chip clearing while limiting the depth of cut and preventing grabbing or overloading. Chipper chains are sometimes used for dirty work, since their very large working corner allows the cutter to retain its effective sharpness for a long time in abrasive conditions.
Powdered alcohol is made by a process called micro-encapsulation. An auxiliary material for a capsule may be any readily water-soluble substance (e.g. carbohydrate such as dextrins (starch hydrolyzate), protein such as gelatin). For powdered alcohol, maltodextrin (a type of dextrin) was chosen. For the process to encapsulate, a method called spray drying was selected. In this process, a mixture of dextrin and the alcoholic drink is subjected to simultaneous spraying and heating. The spraying converts the liquid to small drops (up to several hundred μm (micrometers) in diameter), and the heat causes the hydrous dextrin to form a film. When the film dries, the drop becomes a microcapsule containing a dehydrated alcoholic drink and dextrin. Drying removes about 90% of the water and 10% of the ethanol from the initial liquid. An explanation for this preferential loss of water over volatile organics like ethanol is called "selective diffusion": a carbohydrate (in this case, maltodextrin) film forms during spray-drying on each droplet. The film allows smaller molecules like water to go through, but not larger ones like ethanol. As a result, more water is lost. The film is formed in about 0.1 second from the creation of the droplet by spraying. There is no time for the internal convection in each drop or capsule to occur. The end result of spray-drying is large amounts of microcapsules with the appearance of a powder. This is powdered alcohol. According to Sato's web page, powdered alcohol contains 30.5% ethyl alcohol by volume in the state of powder.
2007 The book Ending Aging written by Aubrey de Grey and his research assistant Michael Rae. 2007 First evidence that a pharmacological agent (namely, metformin) at a certain dosage is capable to increase the lifespan of mice. 2008 Foundation of the Max Planck Institute for Biology of Ageing. 2008 (approximately) It was observed that different variants of FOXO3 gene are associated with human longevity. Since then, research has been conducted to better understand its functions and the mechanism of action. 2009 Association of genetic variants in insulin/IGF1 signaling with human longevity. 2009 A second pharmacological agent (namely, rapamycin) was shown to be capable to increase the lifespan of mice. For this discovery Dave Sharp receive a special prize from the Methuselah Foundation. 2009 The SENS Research Foundation, a research institute dedicated to studying the aging process and ways to reverse it based on the strategies for engineered negligible senescence approach, was established by Aubrey de Grey. 2010s first half The appearance of small political parties in different countries that make the promotion of anti-aging technologies part of their political platforms (for example, Science Party of Australia, U.S. Transhumanist Party, Party for Rejuvenation Research). 2010 Harvard University scientists at the Dana–Farber Cancer Institute partially reversed age-related degeneration in mice by engineering an improved telomerase gene. 2012 It was discovered that protein Sirtuin 6 (SIRT6) regulates the lifespan of male mice (but not female mice).
=== Calcium and calmodulin dependence === The sensitivity of the CaMKII enzyme to calcium and calmodulin is governed by the variable and self-associative domains. This sensitivity level of CaMKII will also modulate the different states of activation for the enzyme. Initially, the enzyme is activated; however, autophosphorylation does not occur because there is not enough calcium or calmodulin present to bind to neighboring subunits. As greater amounts of calcium and calmodulin accumulate, autophosphorylation occurs leading to persistent activation of the CaMKII enzyme for a short period of time. However, the Threonine 286 residue eventually becomes dephosphorylated, leading to inactivation of CaMKII.
Dinoflagellates are the primary source of dinosteral. Dinoflagellates are unicellular, aquatic organisms that live in both marine and inland environments and are a prominent constituent of phytoplankton. Dinoflagellates are often characterized by their uncommon sterol distribution, dominated by 4α-methyl sterols derived from lanosterol rather than cycloartenol. In many cases, the most abundant sterol in dinoflagellates is dinosterol. Dinosterol is often used a biomarker in geochemical research because it is produced almost exclusively by dinoflagellates and is found in many environments. In addition to several species of dinoflagellates, dinosterol has also been isolated from the diatom Nivicula sp. (CS-46c) collected from Port Hacking, New South Wales, Australia.
Sources: en.wikipedia.org
Yes, the terms are generally interchangeable. Lyophilization is more common in pharmaceutical and laboratory contexts, while freeze-drying appears widely in food science and general writing. Both describe removal of solvent by sublimation under vacuum after freezing.
Reduced pressure keeps the process below the triple point of water, so ice can sublimate directly to vapor. It also lowers the temperature needed for drying, which helps preserve heat-sensitive materials. Without vacuum, melting or boiling could occur instead of controlled sublimation.
The rate depends on heat transfer to the product and mass transfer of vapor through the dried layer. A cold condenser, adequate vacuum, and suitable shelf temperature all influence speed. Formulation properties such as solid content and collapse temperature also set practical limits.
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.