The short version of Sublimation fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-02-06. Anything still debated is marked as such rather than presented as settled.
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 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.
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.
| Property | Value | Notes |
|---|---|---|
| Physical state | Solid, porous cake or powder | Depends on formulation and container |
| Typical storage temperature | 2–25 °C, protected from moisture | Some materials require colder conditions |
| Solubility class | Usually readily soluble after reconstitution | Not an intrinsic chemical property |
| Common analytical method | Karl Fischer titration | Used for residual moisture |
| Common synonyms | Freeze-drying; lyophilisation | Lyophilisation is a spelling variant |
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.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and fixes the structure of the sample. After freezing, primary drying lowers pressure so ice changes directly to vapor without passing through a liquid phase. Secondary drying then removes bound water that remains after ice sublimation. The result is a dry, porous solid that often retains its original shape.
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.
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.
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.
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.
In non-small cell lung cancer, both mRNA and protein levels of TMPRSS11D are elevated in tumor tissue compared with adjacent normal tissue, and high protein expression is an independent predictor of poorer overall survival. Plasminogen (PLG), from which originates the mini-plasmin that can cleave the F-protein, is highly expressed in liver cancers. Its expression is also increased in a wide range of other malignant neoplasms. Factor X (F10) is frequently expressed in normal liver and in liver cancers. SeV constructs were created with a modified protease cleavage site. The modification allowed the recombinant virus to specifically infect cancer cells that expressed the corresponding proteases, which can cleave a modified protease cleavage site.
Perforated septum – The reconstruction of a saddle nose caused by a (collapsed) perforated septum, or by autoimmune problems such as granulomatosis with polyangiitis (GPA), sarcoidosis, eosinophilic granulomatosis with polyangiitis (EGPA), relapsing polychondritis, by intranasal drug use, and by excessive nasal aerosol use. The saddle nose deformity resulting from lost dorsum support is reconstructed using autologous bone grafts and rib cartilage grafts. Rhinophyma – The correction of late-stage Rosacea, wherein the nasal skin is infected with acne rosacea that reddens, thickens, and enlarges the nose tip; an exemplar case is the American actor W.C. Fields. Although antibiotic acne treatments (e.g. Acutane) can halt the progression of Rosacea, the thickened skin and the fleshy obscuring of the nasal tip can only be corrected with rhinoplasty. Laser excision of abnormally thickened skin is the best rhinoplastic treatment for Rhinophyma; the CO2 laser and the infrared Erbium: YAG laser are the most effective treatments.
Frozen vegetables are vegetables that have had their temperature reduced and maintained to below their freezing point for the purpose of storage and transportation (often for far longer than their natural shelf life would permit) until they are ready to be eaten. It is a type of frozen food, for food preservation. They may be commercially packaged or frozen at home. A wide range of frozen vegetables are sold in supermarkets. Examples of frozen vegetables which can be found in supermarkets include spinach, broccoli, cauliflower, peas, sweetcorn, yam (in Asia) either packaged as a single ingredient or as mixtures. There are occasions when frozen vegetables are mixed with other food types, such as pasta or cheese. Frozen fruits are produced using a very similar approach. Some popular brands include Birds Eye and Green Giant, as well as supermarkets' 'store brand' items. Frozen vegetables have some advantages over fresh ones, in that they are available when the fresh counterpart is out-of-season, they have a very long shelf life when kept in a freezer and that they often have been processed a step or more closer to eating (usually washed and cut, sometimes also seasoned). In many cases, they may be more economical to purchase than their fresh counterparts or are packaged while ripe. The history of frozen fruits can date back to the Liao Dynasty of China, with the "frozen" pear being a classic delicacy eaten by the Khitan tribes in the Northeastern region of China. Modern frozen vegetables with the flash freezing technique was popularized by Clarence Birdseye in 1929.
Dyson also did work in a variety of topics in mathematics, such as topology, analysis, number theory and random matrices. In 1973 the number theorist Hugh Lowell Montgomery was visiting the Institute for Advanced Study and had just made his pair correlation conjecture concerning the distribution of the zeros of the Riemann zeta function. He showed his formula to the mathematician Atle Selberg, who said that it looked like something in mathematical physics and that Montgomery should show it to Dyson, which he did. Dyson recognized the formula as the pair correlation function of the Gaussian unitary ensemble, which physicists have studied extensively. This suggested that there might be an unexpected connection between the distribution of primes (2, 3, 5, 7, 11, ...) and the energy levels in the nuclei of heavy elements such as uranium. Around 1979 Dyson worked with the Institute for Energy Analysis on climate studies. This group, under Alvin Weinberg's direction, pioneered multidisciplinary climate studies, including a strong biology group. Also during the 1970s, Dyson worked on climate studies conducted by the JASON defense advisory group. Dyson retired from the Institute for Advanced Study in 1994. In 1998 he joined the board of the Solar Electric Light Fund. In 2003 he was president of the Space Studies Institute, the space research organization founded by Gerard K. O'Neill; in 2013 he was on its board of trustees. Dyson was a longtime member of the JASON group. Dyson won numerous scientific awards, but never a Nobel Prize.
Sources: en.wikipedia.org
Beta hairpin Extremely common. Two antiparallel beta strands connected by a tight turn of a few amino acids between them. Greek key Four beta strands, three connected by hairpins, the fourth folded over the top. Omega loop A loop in which the residues that make up the beginning and end of the loop are very close together. Helix-loop-helix Consists of alpha helices bound by a looping stretch of amino acids. This motif is seen in transcription factors. Zinc finger Two beta strands with an alpha helix end folded over to bind a zinc ion. Important in DNA binding proteins. Helix-turn-helix Two α helices joined by a short strand of amino acids and found in many proteins that regulate gene expression. Nest Extremely common. Three consecutive amino acid residues form an anion-binding concavity. Niche Extremely common. Three or four consecutive amino acid residues form a cation-binding feature.
=== Overdose === Human tolerance to xylazine varies widely, with toxicity and fatality occurring between doses of 40–2,400 mg (0.62–37.04 gr). Non-fatal blood or plasma concentration ranges from 0.03 to 4.6 mg/L. In fatalities, the blood concentration of xylazine ranges from trace to 16 mg/L. It is reported that there is no defined safe or fatal concentration of xylazine because of the significant overlap between the non-fatal and postmortem blood concentrations of xylazine. Hemodialysis has been suggested as a form of treatment, but is usually unfavorable due to the large volume of distribution of xylazine. There are no standardized screenings to determine if an overdose has occurred. Detection of xylazine in humans involves various screening methods, such as urine screenings, thin layer chromatography (TLC), gas chromatography–mass spectrometry (GC-MS) and liquid chromatography–mass spectrometry (LC-MS). As of November 2022, detecting xylazine in a drug sample requires spectrophotometry. As of 1998, the α2-adrenergic receptor antagonist atipamezole was used to reverse the effects of xylazine or the related drug dexmedetomidine in veterinary medicine, but this is not an approved medical treatment for humans, despite Phase I clinical trials in 2005. As of 2001, the effects of xylazine in animals were also reversed by the analeptics 4-aminopyridine, doxapram, and caffeine, which are physiological antagonists to central nervous system depressants. The ways to accurately identify chronic xylazine use are unknown, and the effective treatments, if any, are not standardized.
Pemetrexed, sold under the brand name Alimta among others, is a chemotherapy medication for the treatment of pleural mesothelioma and non-small cell lung cancer (NSCLC). It is available as a generic medication.
== Oxford == Heseltine campaigned briefly as a volunteer in the October 1951 general election before going up to Pembroke College, Oxford. While there, in frustration at his inability to be elected to the committee of the Oxford University Conservative Association, he founded the breakaway Blue Ribbon Club. Along with undergraduates Guy Arnold, Julian Critchley and Martin Morton he canvassed workers at the gates of the Vickers Shipyard in Barrow-in-Furness. Julian Critchley recounted a story from his student days of how he plotted his future on the back of an envelope, a future that would culminate as prime minister in the 1990s. A more detailed apocryphal version has him writing down: 'millionaire 25, cabinet member 35, party leader 45, prime minister 55,' though Heseltine himself disputes this and instead recalls a lack of self-belief. He became a millionaire and was a member of the Cabinet from the age of 46, but narrowly failed to become Party Leader or prime minister. His biographers Michael Crick and Julian Critchley (who was a contemporary of Heseltine's at Brockhurst Prep School) recount how, despite not having an innate gift for public speaking, he became a strong orator through much effort, which included practising his speeches in front of a mirror, listening to tape recordings of speeches by television administrator Charles Hill, and taking voice-coaching lessons from a vicar's wife.
These kinases consist of extracellular domains, a transmembrane spanning alpha helix, and an intracellular tyrosine kinase domain protruding into the cytoplasm. They play important roles in regulating cell division, cellular differentiation, and morphogenesis. More than 50 receptor tyrosine kinases are known in mammals.
Sources: en.wikipedia.org
Freezing only converts liquid to solid. Lyophilization adds vacuum and controlled warming so frozen solvent sublimes, leaving a dry porous solid. The two steps are related but not interchangeable.
Reduced pressure keeps the solvent below its triple point, allowing ice to become vapor without melting. Vacuum also helps remove water vapor from the product chamber. The exact pressure is chosen with the formulation and equipment.
Residual moisture is water that remains in the dried solid after secondary drying. It is often measured by Karl Fischer titration, near-infrared spectroscopy, or thermogravimetry. Acceptable levels depend on the material and its stability profile.
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.