Everything below concerns sublimation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-11-28. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilization is the American spelling; lyophilisation is British |
| Primary drying mechanism | Sublimation of ice | Occurs under vacuum below the triple point |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product and equipment |
| Typical shelf temperature during freezing | -40 to -20 °C | Lower temperatures may be used for labile products |
| Resulting product form | Porous cake or powder | Appearance depends on formulation and cycle |
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.
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.
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.
=== Biology === In modern biological analysis, various kinds of organic dyes are used. However, as technology advances, greater flexibility in these dyes is sought. To this end, quantum dots have quickly filled in the role, being found to be superior to traditional organic dyes on several counts, one of the most immediately obvious being brightness (owing to the high extinction coefficient combined with a comparable quantum yield to fluorescent dyes) as well as their stability (allowing much less photobleaching). It has been estimated that quantum dots are 20 times brighter and 100 times more stable than traditional fluorescent reporters. For single-particle tracking, the irregular blinking of quantum dots is a minor drawback. However, there have been groups which have developed quantum dots which are essentially nonblinking and demonstrated their utility in single-molecule tracking experiments. The use of quantum dots for highly sensitive cellular imaging has seen major advances. The improved photostability of quantum dots, for example, allows the acquisition of many consecutive focal-plane images that can be reconstructed into a high-resolution three-dimensional image. Another application that takes advantage of the extraordinary photostability of quantum dot probes is the real-time tracking of molecules and cells over extended periods of time. Antibodies, streptavidin, peptides, DNA, nucleic acid aptamers, or small-molecule ligands can be used to target quantum dots to specific proteins on cells.
Brandenburg was created out of the major part of the Prussian province of that name Mecklenburg-Vorpommern was created out of the state of Mecklenburg (reunited out of Mecklenburg-Schwerin and Mecklenburg-Strelitz only in 1934) and the Western parts of the Prussian province of Pomerania Saxony (Sachsen) was augmented by the westernmost parts of the Prussian province of Lower Silesia. Also, the town of Reichenau was ceded to Poland. Saxony-Anhalt (Sachsen-Anhalt) was created out of most of the Prussian Province of Saxony and the Free State of Anhalt Thuringia (Thüringen) was augmented by neighbouring parts from the Prussian provinces of Saxony and Hesse-Nassau. In 1949, the Soviet occupation zone was transformed into the German Democratic Republic. The five Länder (and East Berlin, though the latter only with consultative votes) participated in the legislative branch through the Länderkammer ('Chamber of States'), which was elected by the Landtage (state parliaments). However, the Länder were not constituting entities forming a federal republic (as in West Germany) but rather decentralised administrative entities of a quasi-unitary state. As a nod to the legal fiction that East Berlin was still occupied territory, it was counted neither as part of Brandenburg, nor as a state in its own right. East Germany claimed Berlin as its capital, a status recognised by virtually all Eastern Bloc countries, and exercised de facto control over East Berlin.
ACTC1 encodes cardiac muscle alpha actin. This isoform differs from the alpha actin that is expressed in skeletal muscle, ACTA1. Alpha cardiac actin is the major protein of the thin filament in cardiac sarcomeres, which are responsible for muscle contraction and generation of force to support the pump function of the heart.
=== Therapeutic effects === Pain relief: Primarily, fentanyl provides the relief of pain by acting on the brain and spinal μ-receptors. Sedation: Fentanyl produces sleep and drowsiness, as the dosage is increased, and can produce the δ-waves often seen in natural sleep on electroencephalogram. Suppression of the cough reflex: Fentanyl can decrease the struggle against an endotracheal tube and excessive coughing by decreasing the cough reflex, becoming useful when intubating people who are awake and have compromised airways. After receiving a bolus dose of fentanyl, people can also experience paradoxical coughing, which is a phenomenon that is not well understood.
=== Chemoenzymatic labeling === Chemoenzymatic labeling provides an alternative strategy to incorporate handles for click chemistry. The Click-IT O-GlcNAc Enzymatic Labeling System, developed by the Hsieh-Wilson group and subsequently commercialized by Invitrogen, utilizes a mutant GalT Y289L enzyme that is able to transfer azidogalactose (GalNAz) onto O-GlcNAc. The presence of GalNAz (and therefore also O-GlcNAc) can be detected with various alkyne-containing probes with identifiable tags such as biotin, dye molecules, and PEG.
Sources: en.wikipedia.org
== Interactions == Few pharmacokinetic drug interactions have been demonstrated in vivo. The manufacturer notes potential pharmacological interactions with opioids, benzodiazepines, barbiturates, ethanol (alcohol), and other central nervous system depressants. Concurrent use of ACE inhibitors and pregabalin may increase the risk of angioedema. Pregabalin may also enhance the fluid-retaining effects of certain antidiabetic agents, such as thiazolidinediones. Pregabalin may independently increase the risk of angioedema, and this risk is further elevated when used in combination with other drugs known to increase the likelihood of angioedema. These drugs include, but are not limited to, certain L-type calcium channel blockers, ACE inhibitors, angiotensin II receptor blockers, and other agents that inhibit the renin–angiotensin–aldosterone system. The combination of pregabalin with opioids is associated with an increased risk of respiratory depression. This interaction reflects both pharmacodynamic and pharmacokinetic mechanisms: pharmacodynamically, pregabalin and opioids produce additive CNS depression, while pharmacokinetically, opioids reduce gastrointenstinal motility, which may prolong gabapentin absorption and raise its plasma concentrations, with a 2017 study finding that use of gabapentin alongside opioids carries an increased risk of opioid-related death. As pregabalin and gabapentin share the same mechanism of action (binding to the α2δ subunit of voltage-gated calcium channels), findings regarding gabapentin are considered likely applicable to pregabalin.
==== Nonhospitalized outpatients ==== In January 2022, a study indicated that nonhospitalized people who were at high risk for COVID‑19 progression had an 87% lower risk of hospitalization or death after a 3-day course of intravenous remdesivir.
The sector is composed of both "dedicated" AI companies, those for which AI is the primary revenue source, and "diversified" companies, which offer AI products and services as part of a broader commercial offering. In 2024, 56% of identified firms were dedicated and 44% were diversified, with the share of diversified companies continuing to grow year-on-year, reflecting the increasing integration of AI across the wider economy. The vast majority (95%) of all identified AI companies are small and medium-sized enterprises (SMEs), with micro-businesses (fewer than 10 employees) accounting for 70% of the sector.
Nd:YAG (Neodymium: Yttrium Aluminium Garnet) laser CO2 laser Diode laser It has been suggested that lasers can give a substantial reduction in bacteria such as Actinobacillus actinomycetemcomitans (Aa) which will reduce inflammation and facilitate the healing process. Laser treatment seems to also have good patient acceptance as patients report minimal pain. Nd:YAG lasers used for curettage of pocket epithelium cause little or no damage to the underlying tissues. Periodontal health and reattachment of gingival tissues to previously infected root surfaces is the goal of periodontal therapy and this is typically achieved through conventional treatment by scaling, root surface instrumentation and ultrasonic instrumentation. Conventional treatment however does not completely remove plaque and calculus and a laser has been suggested as an effective tool for periodontal treatment because:
Sources: en.wikipedia.org
Water is an inorganic compound with the chemical formula H2O. It is a transparent, tasteless, odorless, and nearly colorless chemical substance. It is the main constituent of Earth's streams, lakes, and oceans. Water is also the fluid of all known living organisms, in which it acts as a solvent. Water, being a polar molecule, undergoes strong intermolecular hydrogen bonding which is a large contributor to its physical and chemical properties. It is vital for all known forms of life, despite not providing food energy or being an organic micronutrient. Due to its presence in all organisms, its chemical stability, its worldwide abundance, and its strong polarity relative to its small molecular size, water is often referred to as the "universal solvent". Because Earth's surface temperature and pressure is relatively close to water's triple point, water exists on Earth as a solid, a liquid, and a gas. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor. Water covers about 71% of the Earth's surface, with seas and oceans making up most of the water volume (about 96.5%). Small portions of water occur as groundwater (1.7%), in the glaciers and the ice caps of Antarctica and Greenland (1.7%), and in the air as vapor, clouds (consisting of ice and liquid water suspended in air), and precipitation (0.001%).
Family studies show that T1D has a relatively high heritability, with siblings of affected individuals having about a 6–10% risk of developing the disease, compared to a 0.3% risk in the general population. The risk of T1D is also influenced by the presence of affected first-degree relatives. For instance, children of fathers with T1D have a higher risk of developing the disease compared to children of mothers with T1D. Monozygotic (identical) twins have a concordance rate of about 30–50%, highlighting the importance of both genetic and environmental factors in disease onset. Recent research has also focused on the role of epigenetics and gene-environment interactions in T1D development. Environmental factors such as viral infections, early childhood diet, and gut microbiome composition are thought to trigger the autoimmune process in genetically susceptible individuals. Epigenetic modifications, such as DNA methylation and histone modifications, may influence gene expression in response to these environmental triggers, further modulating the risk of developing T1D. While much progress has been made in understanding the genetic basis of T1D, ongoing research aims to unravel the complex interplay between genetic susceptibility, immune regulation, and environmental influences that contribute to disease pathogenesis.
A prolonged-release 2 mg oral formulation of melatonin sold under the brand name Circadin is approved for use in the European Union in the short-term treatment of insomnia in people aged 55 years of age or older. Melatonin is also available as an over-the-counter dietary supplement in many countries. It is available in both immediate-release and less commonly prolonged-release forms. The compound is available in supplements at doses ranging from 0.3 mg to 10 mg or more. It is also possible to buy raw melatonin powder by weight. Immediate-release formulations of melatonin cause blood levels of melatonin to reach their peak in about an hour. The hormone may be administered orally, as capsules, gummies, tablets, oral films, or as a liquid. It is also available for use sublingually, or as transdermal patches. Several inhalation-based melatonin products with a wide range of doses are available but their safety remains to be evaluated.
The United States military began executing airstrikes on vessels in the Caribbean Sea in September 2025, described by the administration of President Donald Trump as part of an effort to fight the flow of illicit drugs from Latin America to the US. In October, the strikes expanded to include vessels in the Eastern Pacific Ocean. The Trump administration has alleged, without producing public evidence, that the vessels were operated by groups it designated as narcoterrorists, including the Venezuelan organization Tren de Aragua and the Colombian far-left guerilla group National Liberation Army. As part of what was later unveiled as Operation Southern Spear, the US began deploying Navy warships and personnel to the Caribbean in mid-August. Trump announced on 2 September that the US Navy had carried out the first airstrike in the Caribbean on a boat from Venezuela, killing all 11 people aboard; he released a video of the incident, which Venezuelan sources said had occurred on 1 September. US officials said that this was a military operation against drug cartels in Latin America and that these military operations would continue. As of 19 September 2026, at least 234 people had been killed (including 17 who are missing and presumed dead) in at least 78 strikes on over 79 vessels and the US had made its first strike on a land target within Venezuela. On 12 June, Niño Guerrero, leader of Tren de Aragua, was killed in joint operation with the post-Maduro Venezuelan government.
In addition to expanding the tandem mass spectrometry database, METLIN is designed to search tandem mass spectrometry data, precursor mass, chemical formulas, compound names among other search capabilities. METLIN has also been implemented with cognitive computing applications. The tandem MS high-resolution ESI-QTOF MS/MS data on now over 960,000 distinct chemical entities, includes mass spectral collision-induced dissociation data at four different collision energies, in both positive and negative ionization modes.
Sources: en.wikipedia.org
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.
Vacuum lowers the pressure below the triple point of water, allowing ice to sublimate directly into vapor. It also helps remove water vapor from the product chamber and shortens primary drying.
Many aqueous solutions and suspensions can be freeze-dried, but some formulations collapse or do not form a stable cake. The process requires careful formulation and cycle development.
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.