This is a working overview of sublimation, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-27 and is reviewed periodically as new material appears.
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 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.
| 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 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.
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.
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.
ISBN 0-921991-50-9. Spaeter, Helmuth (1990). Panzerkorps Grossdeutschland: A Pictorial History. Atglen, Pennsylvania: Schiffer Books. ISBN 0-88740-245-3. Ziemke, Earl F. (2002). Stalingrad to Berlin: The German Defeat in the East. Washington, D.C.: Center of Military History. ISBN 978-1-78039-287-5.
Doxycycline, sold under the brand names Vibramycin and Doryx, among others, is a broad-spectrum antibiotic of the tetracycline class used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, and syphilis, and is sometimes used to prevent malaria. Doxycycline may be taken by mouth or intravenously. Common side effects include diarrhea, nausea, vomiting, abdominal pain, and an increased risk of sunburn. Use during pregnancy is not recommended. Doxycycline can be used in children of all ages, including for Lyme disease and rickettsial infections. Like other agents of the tetracycline class, it slows or kills bacteria by inhibiting protein production. It kills Plasmodium—microorganisms associated with malaria—by targeting a plastid organelle, the apicoplast. Doxycycline post-exposure prophylaxis (doxyPEP) is also used to prevent sexually transmitted infections, particularly when skin or fluid contact has occurred, such as if protection was not used in men who have sex with men, and is supported by CDC guidelines.
In the development of the embryo, at 3–4 weeks gestational age, the thyroid gland appears as an epithelial proliferation in the floor of the pharynx at the base of the tongue between the tuberculum impar and the copula linguae. The copula soon becomes covered over by the hypopharyngeal eminence at a point later indicated by the foramen cecum. The thyroid then descends in front of the pharyngeal gut as a bilobed diverticulum through the thyroglossal duct. Over the next few weeks, it migrates to the base of the neck, passing in front of the hyoid bone. During migration, the thyroid remains connected to the tongue by a narrow canal, the thyroglossal duct. At the end of the fifth week the thyroglossal duct degenerates, and over the following two weeks the detached thyroid migrates to its final position. The fetal hypothalamus and pituitary start to secrete thyrotropin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH). TSH is first measurable at 11 weeks. By 18–20 weeks, the production of thyroxine (T4) reaches a clinically significant and self-sufficient level. Fetal triiodothyronine (T3) remains low, less than 15 ng/dL until 30 weeks, and increases to 50 ng/dL at full-term. The fetus needs to be self-sufficient in thyroid hormones in order to guard against neurodevelopmental disorders that would arise from maternal hypothyroidism. The presence of sufficient iodine is essential for healthy neurodevelopment. The neuroendocrine parafollicular cells, also known as C cells, responsible for the production of calcitonin, are derived from foregut endoderm.
This article incorporates text from this source, which is in the public domain. Japan: A Country Study. Federal Research Division. Benesch, Oleg (2018). "Castles and the Militarisation of Urban Society in Imperial Japan" (PDF). Transactions of the Royal Historical Society. 28: 107–134. doi:10.1017/S0080440118000063. S2CID 158403519. Archived from the original (PDF) on November 20, 2018. Retrieved November 25, 2018. Earle, Joe (1999). Splendors of Meiji : treasures of imperial Japan : masterpieces from the Khalili Collection. St. Petersburg, Fla.: Broughton International Inc. ISBN 1874780137. OCLC 42476594. Guth, Christine M. E. (2015). "The Meiji era: the ambiguities of modernization". In Jackson, Anna (ed.). Kimono: the art and evolution of Japanese fashion. London: Thames & Hudson. pp. 106–111. ISBN 9780500518021. OCLC 990574229. Iwao, Nagasaki (2015). "Clad in the aesthetics of tradition: from kosode to kimono". In Jackson, Anna (ed.). Kimono: the art and evolution of Japanese fashion. London: Thames & Hudson. pp. 8–11. ISBN 9780500518021. OCLC 990574229. Kublin, Hyman (November 1949). "The "modern" army of early meiji Japan". The Far Eastern Quarterly. 9 (1): 20–41. doi:10.2307/2049123. JSTOR 2049123. S2CID 162485953. Jackson, Anna (2015). "Dress in the Meiji period: change and continuity". In Jackson, Anna (ed.). Kimono: the art and evolution of Japanese fashion. London: Thames & Hudson. pp. 112–151. ISBN 9780500518021. OCLC 990574229. National Diet Library (n.d.). Osaka army arsenal (osaka hohei kosho). Retrieved August 5, 2008.
Sources: en.wikipedia.org
Tachykinin peptides are also involved in inflammation, and tachykinin receptor antagonists have been researched for use in treating inflammatory conditions such as asthma and irritable bowel syndrome. The main use for which these antagonist drugs have been applied so far, however, is as antiemetics, in both human and veterinary medicine. Examples of tachykinin antagonists include:
Some of the most striking advances in early anatomy and physiology took place in Hellenistic Alexandria. Two of the most famous anatomists and physiologists of the third century BC were Herophilus and Erasistratus. These two physicians helped pioneer human dissection for medical research, using the cadavers of condemned criminals, which was considered taboo until the Renaissance—Herophilus was recognized as the first person to perform systematic dissections. Herophilus became known for his anatomical works, making impressive contributions to many branches of anatomy and many other aspects of medicine. Some of the works included classifying the system of the pulse, the discovery that human arteries had thicker walls than veins, and that the atria were parts of the heart. Herophilus's knowledge of the human body has provided vital input towards understanding the brain, eye, liver, reproductive organs, and nervous system and characterizing the course of the disease. Erasistratus accurately described the structure of the brain, including the cavities and membranes, and made a distinction between its cerebrum and cerebellum.During his study in Alexandria, Erasistratus was particularly concerned with studies of the circulatory and nervous systems. He could distinguish the human body's sensory and motor nerves and believed air entered the lungs and heart, which was then carried throughout the body. His distinction between the arteries and veins—the arteries carrying the air through the body, while the veins carry the blood from the heart was a great anatomical discovery.
Early in the 21st century, roughly two-thirds of the world's cocoa was produced in West Africa, with 43% sourced from Ivory Coast, which commonly used child labor. That year some 50 million people around the world depended on cocoa as a source of livelihood. As of 2007 in the UK, most chocolatiers purchase their chocolate from them, to melt, mold and package to their own design. The two main jobs associated with creating chocolate candy are chocolate makers and chocolatiers. Chocolate makers use harvested cocoa beans and other ingredients to produce couverture chocolate (covering). Chocolatiers use the finished couverture to make chocolate candies (bars and truffles). Production costs can be decreased by reducing cocoa content, usually by substituting cocoa butter with another fat. Cocoa growers object to allowing the resulting food to be called "chocolate", due to the risk of lower demand for their crops.
=== Soldiers === For Army Reserve soldiers, recruit training is structured into two phases: Phase 1, also known as the Common Military Syllabus (Recruit) (CMS(R)), and Phase 2, specialist training. Phase 1 In Phase 1, recruits cover the Common Military Syllabus (Reserve)14 (CMS(R)14). Phase 1 A is a series of 5 training weekends at regional Army Training Units (ATUs), or the recruit could attend a consolidated Phase 1 A 9-day long course. Phase 1 training concludes with a 16-day long Phase 1 B training course normally held at the Army Training Centre Pirbright or the Army Training Regiment, Winchester, or Grantham. Recruits to the 4th Battalion, The Parachute Regiment and the Honourable Artillery Company complete their equivalent of CMS(R) within their own units. Phase 2 Phase 1 is followed by Phase 2, a further period of specialist training specific to the type of unit the recruit is joining. This is normally conducted by the Arm or Service that the recruit is joining; for example, for infantry units, Phase 2 consists of the two-week Combat Infantryman's Course (TA) (CIC (TA)) held at the Infantry Training Centre, Catterick.
=== CPT-II deficiency === Carnitine palmitoyltransferase II deficiency (also known as CPT-II deficiency) leads to an excess long chain fatty acids, as the body lacks the ability to transport fatty acids into the mitochondria to be processed as a fuel source. The disease is caused by a defect in the gene CPT2. This deficiency will present in patients in one of three ways: lethal neonatal, severe infantile hepatocardiomuscular, and myopathic form. The myopathic is the least severe form of the deficiency and can manifest at any point in the lifespan of the patient. The other two forms appear in infancy. Common symptoms of the lethal neonatal form and the severe infantile forms are liver failure, heart problems, seizures and death. The myopathic form is characterized by muscle pain and weakness following vigorous exercise. Treatment generally includes dietary modifications and carnitine supplements.
Sources: en.wikipedia.org
=== Based on evolutionary phylogeny === An up-to-date classification of protease evolutionary superfamilies is found in the MEROPS database. In this database, proteases are classified firstly by 'clan' (superfamily) based on structure, mechanism and catalytic residue order (e.g. the PA clan where P indicates a mixture of nucleophile families). Within each 'clan', proteases are classified into families based on sequence similarity (e.g. the S1 and C3 families within the PA clan). Each family may contain many hundreds of related proteases (e.g. trypsin, elastase, thrombin and streptogrisin within the S1 family). Currently more than 50 clans are known, each indicating an independent evolutionary origin of proteolysis.
== Exocrine cell type == Morphology is what identifies ductal cells. However, there is barely anything to differentiate pancreatic ductal cells from other bodily ductal cells. There is still a lot unknown about these ductal cells. Their molecular identity still needs to be improved; more knowledge is necessary regarding stage-specific markers and the regulators of ductal cell development. It recently was discovered that the ducts start as separate microlumens in a stratified epithelium that expand, attach, and resolve to form the pancreatic ducts. These cells work with intercalating ducts that link to distinct acini and are within the larger ducts in the two core pancreatic ducts (dorsal and ventral duct) that drain into the intestine. Ductal cells are exocrine, but they are more like endocrine cells when developing. A recent lineage analysis showed that ductal cells came directly from bipotent precursor cells and have the possibility of creating either ductal or endocrine cells. Meanwhile, mature ducts have a restricted ability to transdifferentiate to other types of cells, even when the pancreas is injured.
== Economy == The Cherokee Nation controls Cherokee Nation Businesses, a holding company which owns companies in gaming, construction, aerospace and defense, manufacturing, technology, real estate, and healthcare industries. The Nation also operates its own housing authority and issues Tribal vehicle and boat tags. The Cherokee Nation's estimated annual economic impact is $1.06 billion on the state's economy, $401 million in salaries, and supports 13,527 Cherokee and non-Cherokee jobs.
== Sources of exposure == Aflatoxin B1 is mostly found in contaminated food and humans are exposed to aflatoxin B1 almost entirely through their diet. Occupational exposure to aflatoxin B1 has also been reported in swine and poultry production. While aflatoxin B1 contamination is common in many staple foods, its production is maximized in foods stored in hot, humid climates. Exposure is therefore most common in Southeast Asia, South America, and Sub-Saharan Africa.
Glycogen storage disease type II (GSD-II), also called Pompe disease, and formerly known as GSD-IIa or Limb–girdle muscular dystrophy 2V, is an autosomal recessive metabolic disorder which damages muscle and nerve cells throughout the body. It is caused by an accumulation of glycogen in the lysosome due to a deficiency of the lysosomal acid alpha-glucosidase enzyme (GAA). The inability to break down glycogen within the lysosomes of cells leads to progressive muscle weakness throughout the body and affects various body tissues, particularly in the heart, skeletal muscles, liver, and the nervous system. GSD-II and Danon disease are the only glycogen storage diseases characterised by a defect in lysosomal metabolism. It was first identified in 1932 by Dutch pathologist Joannes Cassianus Pompe, making it the first glycogen storage disease to be discovered.
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.
Conventional drying uses heat to evaporate water from a material, while lyophilization freezes the material and removes water by sublimation under vacuum. This avoids the liquid phase and reduces thermal damage to sensitive substances. The result is a porous cake that reconstitutes quickly.