This is a working overview of primary drying, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-01-24. Anything still debated is marked as such rather than presented as settled.
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 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.
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.
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; cryodesiccation | Regional spelling and historical terms. |
| Primary drying pressure | 0.05-0.5 mbar (5-50 Pa) | Kept below the triple point of water; product-specific. |
| Shelf temperature range | -40 to +40 °C | Freezing, primary, and secondary stages use different set points. |
| Cycle duration | 12-72 hours | Depends on fill volume, formulation, and equipment. |
| Condenser temperature | -50 to -80 °C | Must remain below the product's ice temperature. |
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.
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.
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 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.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
== Research == (R)-MDMA is under development separately by AtaiBeckley, Empath Biosciences (EmpathBio) and Definium Therapeutics (formerly MindMed). It is being developed by AtaiBeckley for social anxiety disorder, by Empath Biosciences for the treatment of PTSD and social phobia and it is being developed by Definium Therapeutics for the treatment of PDDs or autism. As of February 2026, the drug is in phase 2 clinical trials for social phobia and autistic spectrum disorders, whereas no recent development has been reported for PTSD. The results of AtaiBeckley's phase 2a trial for treatment of social phobia have been released, with the drug showing moderate effectiveness and a generally favorable safety profile for this indication.
=== Interfering with receptor signaling and inactivating signaling ligands === The growth of tumor cells can be stimulated or modulated by receptor tyrosine kinase (RTKs), including members of the Her family or insulin-like growth factor (IGF). The RTKs are therefore preferred targets in cancer therapy. Although monospecific RTK-targeting IgGs have already been available in the market, such as cetuximab (Erbitux) and panitumumab (Vectibix), both of which are directed against HER1. However, cancer cells can switch to a different pathway to escape the growth inhibition generated by blocking one signaling pathway. To improve the therapeutic efficacy, simultaneously interfering/blocking of two (or more) RTK signaling pathways, achieved through the mediation of BsAb to inactivate either the RTKs or their ligand, reduces the possibility of the escape mechanisms adopted by the tumor cells. In addition, in working with Ebolavirus vaccines, a study has shown that a DVD-Ig antibody can be used to prevent viral escape from the endosome. Ebolaviruses infect cells by receptor-mediated endocytosis. Researchers developed DVD-Igs where the outer variable regions bind to the surface glycoproteins of the viral coat and enter the cell with the virus. These outer regions are cleaved in the viral endosome, revealing the inner variable regions that then bind to both the virus and internal receptors in the endosome. Blocking the interaction between the virus and endosomal proteins prevents viral escape from the endosome and further infection.
Hunger has been a perennial human problem. However, until the early 20th century, there was relatively little awareness of the qualitative aspects of malnutrition. Throughout history, various peoples have known the importance of eating certain foods to prevent symptoms now associated with malnutrition. Yet such knowledge appears to have been repeatedly lost and then re-discovered. For example, the ancient Egyptians reportedly knew the symptoms of scurvy. Much later, in the 14th century, Crusaders sometimes used anti-scurvy measures – for example, ensuring that citrus fruits were planted on Mediterranean islands, for use on sea journeys. However, for several centuries, Europeans appear to have forgotten the importance of these measures. They rediscovered this knowledge in the 18th century, and by the early 19th century, the Royal Navy was issuing frequent rations of lemon juice to every crewman on their ships. This massively reduced scurvy deaths among British sailors, which in turn gave the British a significant advantage in the Napoleonic Wars. Later on in the 19th century, the Royal Navy replaced lemons with limes (unaware at the time that lemons are far more effective at preventing scurvy).
The French Wars of Religion in the 16th century and the French Revolution in the 18th successively destroyed much of what existed in the way of the architectural and artistic remnant of this Norman creativity. The former, with their violence, caused the wanton destruction of many Norman edifices; the latter, with its assault on religion, caused the purposeful destruction of religious objects of any type, and its destabilisation of society resulted in rampant pillaging. By far the most famous work of Norman art is the Bayeux Tapestry, which is not a tapestry but a work of embroidery. It was commissioned by Odo, the Bishop of Bayeux and first Earl of Kent, employing natives from Kent who were learned in the Nordic traditions imported in the previous half century by the Danish Vikings. In Britain, Norman art primarily survives as stonework or metalwork, such as capitals and baptismal fonts. In southern Italy, however, Norman artwork survives plentifully in forms strongly influenced by its Greek, Lombard, and Arab forebears. Of the royal regalia preserved in Palermo, the crown is Germanic and Byzantine in style and the coronation cloak is of Arab craftsmanship with Arabic inscriptions. Many churches preserve sculptured fonts, capitals, and more importantly mosaics, which were common in Norman Italy and drew heavily on the Greek heritage. Lombard Salerno was a centre of ivorywork in the 11th century and this continued under Norman domination.
Sources: en.wikipedia.org
The study of venom evolution has been a high priority for scientists in terms of scientific research, due to the medical relevance of snake venom, in terms of making antivenom and cancer research. Knowing more about the composition of venom and the ways it can potentially evolve is very beneficial. Three main factors that affect venom evolution have been closely studied: predators of the snake that are resistant to snake venom, prey that are in an evolutionary arms race with snakes, and the specific diets that affect the intraspecific evolution of venom. Venoms continue to evolve as specific toxins and are modified to target a specific prey, and toxins are found to vary according to diet in some species. Rapid venom evolution can also be explained by the arms race between venom-targeted molecules in resistant predators, such as the opossum, and the snake venom that targets the molecules. Scientists performed experiments on the opossums and found that multiple trials showed replacement to silent substitutions in the von Willebrand factor (vWf) gene that encodes for a venom-targeted hemostatic blood protein. These substitutions are thought to weaken the connection between vWf and a toxic snake venom ligand (botrocetin), which changes the net charge and hydrophobicity. These results are significant to the venom evolution because it's the first citation of rapid evolution in a venom-targeted molecule. This shows that an evolutionary arms race may be occurring in terms of defensive purposes.
Saffron contains some 28 volatile and aroma-yielding compounds, dominated by ketones and aldehydes. Its main aroma-active compounds are safranal – the main compound responsible for saffron aroma – 4-ketoisophorone, and dihydrooxophorone. Saffron also contains nonvolatile phytochemicals, including the carotenoids zeaxanthin, lycopene, various α- and β-carotenes, as well as crocetin and its glycoside crocein, which are the most biologically active components. Because crocetin is smaller and more water-soluble than the other carotenoids, it is more rapidly absorbed. The yellow-orange colour of saffron is primarily the result of α-crocin. This crocin is trans-crocetin di-(β-D-gentiobiosyl) ester; it bears the systematic (IUPAC) name 8,8-diapo-8,8-carotenoic acid. This means that the crocin underlying saffron's aroma is a digentiobiose ester of the carotenoid crocetin. Crocins themselves are a series of hydrophilic carotenoids that are either monoglycosyl or diglycosyl polyene esters of crocetin. Crocetin is a conjugated polyene dicarboxylic acid that is hydrophobic, and thus oil-soluble. When crocetin is esterified with two water-soluble gentiobioses, which are sugars, a product results that is itself water-soluble. The resultant α-crocin is a carotenoid pigment that may make up more than 10% of dry saffron's mass. The two esterified gentiobioses make α-crocin ideal for colouring water-based and non-fatty foods such as rice dishes. The bitter glucoside picrocrocin is responsible for saffron's pungent flavour.
== Plot == In early 2016, one to two months after the events of the "Cold War" operation, The Hong Kong Police Force holds a funeral for two Senior Assistant Commissioners killed previously. Shortly after, Commissioner Sean Lau receives a call from one of the culprits behind the theft of the police van. He is told that his wife has been kidnapped and that he must release Joe Lee for her to survive. Lau overrides standard procedure to transfer Joe out of prison, and is told by the kidnapper to bring Joe to the metro station. There, Joe is able to escape with the aid of several accomplices, one of whom sets off a bomb. The culprits leave Lau's wife alive at their hideout. Lau's actions are criticized by the media and by numerous politicians, leading to a public inquiry. Fearing that the police have been infiltrated, Lau privately requests Billy Cheung, an ICAC Principal Investigator who assisted him previously, to form a separate squad independent of the police in order to track the culprits. Meanwhile, MB Lee, the deputy police commissioner approaching retirement, is confronted by his fugitive son along with Peter Choi, a former police commissioner and Lee's former mentor who is now manipulating politics behind the scenes. Choi is revealed as the mastermind behind the troubles of the EU police van disappearance, and his current goal is to remove Lau, who is not a member of his ring, and to place his own followers into positions of power during the next election.
=== Anorexia === Interactions between MCH and chemokines/cytokines that lead to an overall decrease in MCH release and neuron excitability has been linked with infection-induced anorexia. Chemokines and cytokines often appear as the result of inflammation or infection, and they can then damage MCH neurons, which can lead to anorexia in an individual.
To import or export, sell or offer for sale, supply—even gratuitously—transport, carry, keep in storage, store, administer, or in any way deliver for consumption any narcotic substance, without authorization or in violation of legal or regulatory provisions. This article rendered these drugs illegal and thus authorized police powers and regulatory bodies to impose sanctions on users and traffickers of illicit drugs. Even before their legal prohibition, narcotic drugs were already shrouded in prejudice—particularly racial prejudice, such as in the case of marijuana, which was nicknamed "Angola weed", because it was mainly used by adherents of Afro-Brazilian religions in their rituals. In 1973, when Brazil acceded to the Convention on Psychotropic Substances, the "war on drugs" shifted its approach; the new drug policies clearly defined the penalties and consequences associated with possessing, purchasing, or selling these substances. It was in the Brazilian state's interest to marginalize and prohibit narcotics, given that during the 1968 student marches against the military dictatorship, drugs had been used as a symbol of resistance against the regime—and, due to the lack of clear penalties, users faced neither prosecution nor punishment.
Sources: en.wikipedia.org
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.
Reduced pressure lowers the boiling point of water and allows ice to sublime at temperatures below freezing. It also helps remove water vapor from the product toward the condenser. The exact pressure is chosen to stay below the triple point of water.
No. Materials with low solids content or high volatile solvents may form weak or collapsed cakes. Some proteins and cells require stabilizers to survive freezing and drying stresses. Feasibility depends on formulation and process design.
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.