The short version of sublimation fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-14. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonym | Freeze-drying | Same dehydration operation |
| Typical vacuum | 10-100 Pa | Pressure during primary drying |
| Primary drying temperature | -40 to -10 °C | Below collapse temperature for many formulations |
| Cycle duration | 12-72 hours | Varies with load, container, and formulation |
| Key phase change | Sublimation | Solid ice to water vapor |
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 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.
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.
=== Ground transportation === The passenger terminal can be accessed from Interstate 240 via Plough Boulevard and Jim McGehee Parkway. It can also be reached via Winchester Road. The airport is served by the Memphis Area Transit Authority route 28 bus, which offers service to Hudson Transit Center in downtown Memphis, as well as Airways Transit Center. The Ground Transportation Center, completed in March 2013, contains the airport's economy parking and parking for all car rental companies. It is seven stories tall and features 4,500 economy parking spaces and 1,200 rental car spaces.
Particle size after micronization is most commonly measured by laser diffraction under USP general chapter <429> and the harmonized ISO 13320 standard, and reported as the volume-weighted D10, D50 and D90 statistics. High-energy mechanical micronization can introduce surface amorphization, polymorphic conversion and triboelectric charging, all of which affect downstream stability and processability and often require post-milling conditioning to control.
== Signs and symptoms == Hypoglycemic symptoms are divided into two main categories. The first category is symptoms caused by low glucose in the brain, called neuroglycopenic symptoms. The second category of symptoms is caused by the body's reaction to low glucose in the blood, called adrenergic symptoms.
=== All Stars game === The biennial All Star game played in the Northern Territory, featuring an AFL team and the Indigenous All Stars team, made up of some of the best Indigenous players in the game, returned for the 2013 pre-season. Richmond were selected as the AFL team to partake in the game, which was played at Traeger Park in Alice Springs.
=== Target identification by chromatographic co-elution (TICC) === Target identification by chromatographic co-elution does not rely on differences in protein stability after drug treatment. Instead, it rests on the assumption that drugs form stable complexes with their target proteins, and that those complexes are robust enough to survive a chromatographic separation. In a typical workflow, a cell lysate is incubated with a drug, then the lysate is injected onto an ion-exchange chromatography system and fractionated. Lysate proteins are eluted along an ionic strength gradient and fractions are collected over short time intervals. Each fraction is analyzed by LC-MS/MS for both protein and drug content. Individual proteins elute with characteristic profiles, and pre-incubated drugs should mirror the elution profiles of the targets they complex with. Correlation of drug and protein elution profiles allows for targets to be narrowed down and inferred.
Sources: en.wikipedia.org
In May–June 1897, Thomson investigated whether or not the rays could be deflected by an electric field. Previous experimenters had failed to observe this, but Thomson believed their experiments were flawed because their tubes contained too much gas. Thomson constructed a Crookes tube with a better vacuum. At the start of the tube was the cathode from which the rays projected. The rays were sharpened to a beam by two metal slits – the first of these slits doubled as the anode, the second was connected to the earth. The beam then passed between two parallel aluminium plates, which produced an electric field between them when they were connected to a battery. The end of the tube was a large sphere where the beam would impact on the glass, created a glowing patch. Thomson pasted a scale to the surface of this sphere to measure the deflection of the beam. Any electron beam would collide with some residual gas atoms within the Crookes tube, thereby ionizing them and producing electrons and ions in the tube (space charge); in previous experiments this space charge electrically screened the externally applied electric field. However, in Thomson's Crookes tube the density of residual atoms was so low that the space charge from the electrons and ions was insufficient to electrically screen the externally applied electric field, which permitted Thomson to successfully observe electrical deflection.
== History == The brewery started as a small, casual pub in the alleyways of Gyeongnidan in Seoul. The idea to start the pub was inspired by Tudor's article in The Economist, which claimed: "brewing remains just about the only useful activity at which North Korea beats the South." The pub began selling Bill's Pale Ale, The Booth's first brew, along with a small selection of pizza. After realizing how crucial the cold chain transportation system was to maintaining the quality and flavor of beer, the owners established the first cold chain import and distribution system, The Booth Cold Chain. This was soon importing beers from Mikkeller, Evil Twin, To Øl, and 8 Wired. Two crowdfunding campaigns titled Equity for Booth were launched, in September 2015 and February 2017.
Freshly made, raw tempeh remains edible for a few days at room temperature. It is neither acidic nor does it contain significant amounts of alcohol. It, however, shows greater resistance to spoilage processes such as lipid peroxidation than unfermented soybeans due to its antioxidant contents. Cooking methods such as tempe kering, the deep-fried and seasoned bits of tempeh allows Tempeh to last for a month or more and still be good to consume, if cooked correctly and stored properly in an air-tight jar. The deep-frying process removes the moisture, preventing further fermentation and deterioration, thus prolonging its shelf life.
There will probably never be another Test match like this. The tension generated by the closeness and importance of the game, combined with the efforts of the protestors inside, outside and above the ground, made for an exhilarating and yet terrifying afternoon. The role of the NZ police also became more controversial as a result of the tour. The NZRFU constitution contained much high-minded wording about promoting the image of rugby and New Zealand, and generally being a benefit to society. In 1985 the NZRFU proposed an All Black tour of South Africa that remobilised New Zealand protesters. Two lawyers successfully sued it, claiming such a tour would breach its constitution. The High Court stopped the tour.
Sources: en.wikipedia.org
== Louisiana Secretary of Revenue (1996–1999) == Following his first stint in state government, Kennedy returned to private law practice until 1996. That year, he was appointed secretary of the state Department of Revenue in the cabinet of Governor Mike Foster. Despite having political differences with Kennedy during his time in Roemer's administration, Foster selected Kennedy for the position and later endorsed him for the U.S. Senate. Kennedy stepped down as secretary in April 1999 and was replaced by Brett Crawford.
They drove into the camp past FRELIMO guards to the parade ground where many were assembled before the attack commenced. The head of the Selous Scouts, Ronald Francis Reid-Daly, claimed that captured ZANLA documents showed that the people killed in the raid were either trained guerrillas or were undergoing guerrilla instruction and training. Paul L. Moorcraft and Peter McLaughlin wrote in 1982, that "although the camp did contain trained guerrillas and young recruits, many of its inhabitants were old people, women and young children who had fled from Rhodesia as refugees". They further wrote in 2010, that "although nearly all the personnel in the camp were unarmed, many were trained guerillas or undergoing instruction" and that documents captured from ZANLA, revealed more than 1,028 were killed in the operation. A 1994 Amnesty International publication described the operation as a massacre and stated that the camp at Nyadzonya housed refugees, and that a soldier who participated in the raid later stated: "We were told that Nyadzonia was a camp containing several thousand unarmed refugees who could be recruited to join the guerrillas. It would be easier if we went in and wiped them out while they were unarmed and before they were trained rather than waiting for the possibility of them being trained and sent back armed into Rhodesia". According to Amnesty International, 1,000 people were killed and the operation was "a gross human rights violation and a war crime".
== Pollution == Selenium pollution might impact some aquatic systems and may be caused by anthropogenic factors such as farming runoff and industrial processes. People who eat more fish are generally healthier than those who eat less, which suggests no major human health concern from selenium pollution, although selenium has a potential effect on humans. Selenium poisoning of water systems may result whenever new agricultural run-off courses through dry lands. This process leaches natural soluble selenium compounds (such as selenates) into the water, which may then be concentrated in wetlands as the water evaporates. Selenium pollution of waterways also occurs when selenium is leached from coal flue ash, mining and metal smelting, crude oil processing, and landfill. High selenium levels in waterways were found to cause congenital disorders in oviparous species, including wetland birds and fish. Elevated dietary methylmercury levels can amplify the harm of selenium toxicity in oviparous species. Selenium is bioaccumulated in aquatic habitats, which results in higher concentrations in organisms than the surrounding water. Organoselenium compounds can be concentrated over 200,000 times by zooplankton when water concentrations are in the 0.5 to 0.8 μg Se/L range. Inorganic selenium bioaccumulates more readily in phytoplankton than zooplankton. Phytoplankton can concentrate inorganic selenium by a factor of 3000. Further concentration through bioaccumulation occurs along the food chain, as predators consume selenium-rich prey.
== Adverse events == In 2005, the FDA announced that they were investigating reports of death and other serious adverse events related to narcotic overdose in patients using Duragesic, the fentanyl transdermal patch for pain control. The Duragesic product label was subsequently updated to add safety information in June 2005. In 2007, Shire and Noven Pharmaceuticals, manufacturers of the Daytrana ADHD patch, announced a voluntary recall of several lots of the patch due to problems with separating the patch from its protective release liner. Since then, no further problems with either the patch or its protective packaging have been reported. In 2008, two manufacturers of the fentanyl patch, ALZA Pharmaceuticals (a division of major medical manufacturer Johnson & Johnson) and Sandoz, subsequently issued a recall of their versions of the patch due to a manufacturing defect that allowed the gel containing the medication to leak out of its pouch too quickly, which could result in overdose and death. As of March 2009, Sandoz—now manufactured by ALZA—no longer uses gel in its transdermal fentanyl patch; instead, Sandoz-branded fentanyl patches use a matrix/adhesive suspension (where the medication is blended with the adhesive instead of held in a separate pouch with a porous membrane), similar to other fentanyl patch manufacturers such as Mylan and Janssen. In 2009, the FDA announced a public health advisory warning of the risk of burns during MRI scans from transdermal drug patches with metallic backings.
After tobacco is harvested, it is cured (dried), and then aged to improve its flavor. There are four common methods of curing tobacco: air curing, fire curing, flue curing, and sun curing. The curing method used depends on the type of tobacco and its intended use. Air-cured tobacco is sheltered from wind and sun in a well-ventilated barn, where it air-dries for six to eight weeks. Air-cured tobacco is low in sugar, which gives the tobacco smoke a light, sweet flavour, and high in nicotine. Cigar and burley tobaccos are air-cured. In fire curing, smoke from a low-burning fire on the barn floor permeates the leaves. This gives the leaves a distinctive smoky aroma and flavor. Fire curing takes three-to-ten weeks and produces a tobacco low in sugar and high in nicotine. Pipe tobacco, chewing tobacco, and snuff are fire-cured. Flue-cured tobacco is kept in an enclosed barn heated by flues (pipes) of hot air, but the tobacco is not directly exposed to smoke. This method produces cigarette tobacco that is high in sugar and has medium-to-high levels of nicotine. It is the fastest method of curing, requiring about a week. Virginia tobacco that has been flue-cured is also called bright tobacco, because flue curing turns its leaves gold, orange, or yellow. Sun-cured tobacco dries uncovered in the sun. This method is used in Greece, Turkey, and other Mediterranean countries to produce oriental tobacco. Sun-cured tobacco is low in sugar and nicotine and is used in cigarettes.
Sources: en.wikipedia.org
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.
Sublimation requires the solvent to remain solid so vapor leaves without passing through a liquid phase. If the product melts, the porous structure can collapse and drying becomes uneven. Maintaining frozen conditions preserves the intended physical form.
No, freeze-drying is a dehydration method, not a sterilization step. It can reduce water activity and limit microbial growth during storage, but it does not reliably kill microbes or remove endotoxins. Sterility must come from separate validated processes.
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.