sublimation is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-11-24. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
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.
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.
| 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 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.
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.
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.
DeepMind is known to have trained the program on over 170,000 protein structures from the Protein Data Bank, a public repository of protein sequences and structures. The program uses a form of attention network, a deep learning technique that focuses on having the AI identify parts of a larger problem, then piece it together to obtain the overall solution. The overall training was conducted on processing power between 100 and 200 GPUs.
IOM Research Report TM/05/03 A normative study of levels of uranium in the urine of personnel in the British Forces Archived 26 July 2011 at the Wayback Machine by B. G. Miller, A. P. Colvin, P. A. Hutchison, H. Tait, S. Dempsey, D. Lewis, C. A. Soutar. IOM Research Report TM/05/08 Opinion on the environmental and health risks posed by depleted uranium by the Scientific Committee on Health and Environmental Risks
==== Side effects and toxicity ==== The most common side effect is diarrhea and dyspepsia, occurring in up to 30% of patients. The most important and serious side effect is lactic acidosis, therefore metformin is contraindicated in advanced chronic kidney disease. Kidney function should be assessed before starting metformin. Phenformin and buformin are more prone to cause acidosis than metformin; therefore they have been practically replaced by it. However, when metformin is combined with other drugs (combination therapy), hypoglycemia and other side effects are possible.
In ruling on the 1986 Huanchaca case involving the slaying of a leading Bolivian scientist, his pilot, and a guide, the Third Criminal Court of Santa Cruz returned a guilty verdict in April 1988 against ten Brazilians and a Colombian, in addition to a Bolivian thought to be dead. The court, however, dismissed charges against five other Bolivian suspects, including several well-known drug traffickers. The freeing of two of the suspects by the Santa Cruz judges prompted the Supreme Court of Justice to demand the resignations of the entire Santa Cruz judiciary because of its leniency toward drug traffickers. Four Santa Cruz judges were dismissed because of irregularities in the Huanchaca case, which in early 1989 remained at an impasse, under advisement in the Supreme Court of Justice. Drug kingpin Roberto Suárez Gómez was arrested in 1988. Under the 1988 Antinarcotics Law, the Judicial Police must report antinarcotics operations to the closest Special Antinarcotics Force district within forty-eight hours. The law also called for the creation of three-judge Special NarcoticsControl Courts or tribunals (Juzgados Especiales de Narcotráfico) with broad responsibilities. In early 1989, the Supreme Court of Justice began appointing judges and lawyers to serve on the new tribunals, two of which began functioning as tribunals of first instance in narcotics-related cases, with jurisdiction for the judicial districts of La Paz, Cochabamba, Santa Cruz, and Beni.
Superficial burns may be managed with little more than simple pain medication, while major burns may require prolonged treatment in specialized burn centers. Cooling with tap water may help pain and decrease damage; however, prolonged cooling may result in low body temperature. Partial-thickness burns may require cleaning with soap and water, followed by dressings. It is not clear how to manage blisters, but it is probably reasonable to leave them intact if small and drain them if large. Full-thickness burns usually require surgical treatments, such as skin grafting. Extensive burns often require large amounts of intravenous fluid, due to capillary fluid leakage and tissue swelling. The most common complications of burns involve infection. Tetanus toxoid should be given if not up to date. In 2015, fire and heat resulted in 67 million injuries. This resulted in about 2.9 million hospitalizations and 176,000 deaths. Among women in much of the world, burns are most commonly related to the use of open cooking fires or unsafe cook stoves. Among men, they are more likely a result of unsafe workplace conditions. Most deaths due to burns occur in the developing world, particularly in Southeast Asia. While large burns can be fatal, treatments developed since 1960 have improved outcomes, especially in children and young adults. In the United States, approximately 96% of those admitted to a burn center survive their injuries. The long-term outcome is related to the size of burn and the age of the person affected.
Sources: en.wikipedia.org
Senescence-associated secretory phenotype (SASP) is a phenotype associated with senescent cells wherein those cells secrete high levels of inflammatory cytokines, immune modulators, growth factors, and proteases. SASP may also consist of exosomes and ectosomes containing enzymes, microRNA, DNA fragments, chemokines, and other bioactive factors. Soluble urokinase plasminogen activator surface receptor is part of SASP, and has been used to identify senescent cells for senolytic therapy. Initially, SASP is immunosuppressive (characterized by TGF-β1 and TGF-β3) and profibrotic, but progresses to become proinflammatory (characterized by IL-1β, IL-6 and IL-8) and fibrolytic. SASP is the primary cause of the detrimental effects of senescent cells. SASP is heterogenous, with the exact composition dependent upon the senescent-cell inducer and the cell type. Interleukin 12 (IL-12) and Interleukin 10 (IL-10) are increased more than 200-fold in replicative senescence in contrast to stress-induced senescence or proteosome-inhibited senescence where the increases are about 30-fold or less. Tumor necrosis factor (TNF) is increased 32-fold in stress-induced senescence, 8-fold in replicative senescence, and only slightly in proteosome-inhibited senescence. Interleukin 6 (IL-6) and interleukin 8 (IL-8) are the most conserved and robust features of SASP. But some SASP components are anti-inflammatory. Senescence and SASP can also occur in post-mitotic cells, notably neurons.
14. Item: If the groze darm [large intestine] or the magen [stomach] or the gederme [entrails] are injured, you can heal it thus: sew it together with a fine thread and sprinkle rot puluer [red powder] on it. The same powder is good for all wounds, and the best can be made thus. Take 9 parts of swartz win [black wine] that is the very reddest and 1 lot of hematite, 1 lot each of nutmeg and white frankincense, 3 lots of gum arabic, 1 lot each of sanguinem draconis [dragon’s blood, sap from the Dracaena cinnabari tree] and mumie [mummy]. Pound that all together, make a powder out of it, and keep it as needed. Despite these injuries, however, the Wound Man is still depicted as standing defiantly alive. This reaffirms the fact that the figure was not intended as a threatening one: instead it explained and glorified the cures and medical treatments available in the texts that he accompanied.
=== Reverence === In some pre-industrial societies, semen and other body fluids were revered because they were believed to be magical. Blood is an example of such a fluid, but semen was also widely believed to be of supernatural origin and effect and was, as a result, considered holy or sacred. The ancient Sumerians believed that semen was "a divine substance, endowed on humanity by Enki", the god of water. The semen of a god was believed to have magical generative powers. In Sumerian mythology, when Enki's seed was planted in the ground, it caused the spontaneous growth of eight previously nonexistent plants. Enki was believed to have created the Tigris and Euphrates rivers by masturbating and ejaculating into their empty riverbeds. The Sumerians believed that rain was the semen of the sky-god An, which fell from the heavens to inseminate his consort, the earth-goddess Ki, causing her to give birth to all the plants of the earth. The orchid's twin bulbs were thought to resemble the testicles, which is the etymology of the disease orchiditis. There was an ancient Roman belief that the flower sprang from the spilled semen of copulating satyrs. In a number of mythologies around the world, semen is often considered analogous to breast milk. In the traditions of Bali, it is considered to be the returning or refunding of the milk of the mother in an alimentary metaphor. The wife feeds her husband who returns to her his semen, the milk of human kindness.
== Further reading == Selassie CD (2003). "History of Quantitative Structure-Activity Relationships" (PDF). In Abraham DJ (ed.). Burger's medicinal Chemistry and Drug Discovery. Vol. 1 (6th ed.). New York: Wiley. pp. 1–48. ISBN 978-0-471-27401-8. Shityakov S, Puskás I, Roewer N, Förster C, Broscheit J (2014). "Three-dimensional quantitative structure-activity relationship and docking studies in a series of anthocyanin derivatives as cytochrome P450 3A4 inhibitors". Advances and Applications in Bioinformatics and Chemistry. 7: 11–21. doi:10.2147/AABC.S56478. PMC 3970920. PMID 24741320.
Sources: en.wikipedia.org
== External links == Official website Centers for Medicare and Medicaid Services in the Federal Register Centers for Medicare & Medicaid Services in the Code of Federal Regulations Centers for Medicare & Medicaid Services reports and recommendations from the Government Accountability Office Grants to States for Medicaid account on USAspending.gov Centers for Medicare and Medicaid Innovation account on USAspending.gov State Grants and Demonstration account on USAspending.gov Centers for Medicare and Medicaid Services apportionments on OpenOMB GitHub Repositories GitHub Repositories for Digital Service at CMS
=== Pain === The weak opioid codeine, in low doses and combined with one or more other drugs, is available in prescription medicines and, in some jurisdictions, without a prescription to treat mild pain. Other opioids are usually reserved for the relief of moderate to severe pain.
=== Animal welfare === Animal welfare groups claim that animal husbandry and urine collection methods used in the production of CEEs cause undue stress and suffering to the mares involved. Animal activists have made claims of abuses ranging from inadequate stall size, long periods of confinement, cumbersome urine collection, and continuous breeding cycles. After reaching advanced age, many of the mares are adopted for recreation use, while some are sent to feed lots for slaughter. Despite the controversy, the USDA called the CEEs HRT industry a model of self-regulation.
Many of the Culture novels in fact contain characters (from within or without the Culture) wondering how far-reaching the Minds' dominance of the Culture is, and how much of the democratic process within it might in fact be a sham: subtly but very powerfully influenced by the Minds in much the same ways Contact and Special Circumstances influence other societies. Refuting this perspective is a constant theme within the series. "Referrers" (humans of especially acute reasoning) are involved in high-level Culture decisions. Humanoid agents are given wide latitude to solve problems without AI oversight and support. Humanoids frequently directly contradict their AI colleagues in the process of 'saving the day'. The Culture can be seen as fundamentally hedonistic (one of the main objectives for any being, including Minds, is to have fun rather than to be "useful"). Minds are constructed, by convention, to care for and value human beings. While a General Contact Unit (GCU) does not strictly need a crew (and could construct artificial avatars when it did), a real human crew adds richness to its existence, and offers distraction during otherwise dull periods. In Consider Phlebas it is noted that Minds still find humans fascinating, especially their odd ability to sometimes achieve similarly advanced reasoning as their much more complex machine brains. To a large degree, the freedoms enjoyed by humans in the Culture are only available because Minds choose to provide them.
== Blood tests == Bilirubin is degraded by light. Blood collection tubes containing blood or (especially) serum to be used in bilirubin assays should be protected from illumination. For adults, blood is typically collected by needle from a vein in the arm. In newborns, blood is often collected from a heel stick, a technique that uses a small, sharp blade to cut the skin on the infant's heel and collect a few drops of blood into a small tube. Non-invasive technology is available in some health care facilities that will measure bilirubin by using a bilirubinometer which shines light onto the skin and calculates the amount of bilirubin by analysing how the light is absorbed or reflected. This device is also known as a transcutaneous bilirubin meter. Bilirubin (in blood) is found in two forms:
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.
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.