Lyophilization raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-04-13 and is reviewed periodically as new material appears.
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.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
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.
| 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 |
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.
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.
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.
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.
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.
Lyophilization removes water by freezing a material and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intermediate liquid state. Because the material remains frozen during primary drying, the structure often stays porous. This porous matrix can rehydrate quickly when water is added back. The low pressure also allows vapor to leave the solid matrix without boiling.
C-5 sterol desaturase (also known as sterol C-5 desaturase and C5SD) is an enzyme that is highly conserved among eukaryotes and catalyzes the dehydrogenation of a C-5(6) bond in a sterol intermediate compound as a step in the biosynthesis of major sterols. The precise structure of the enzyme's substrate varies by species. For example, the human C-5 sterol desaturase (also known as lathosterol oxidase) oxidizes lathosterol, while its ortholog ERG3 in the yeast Saccharomyces cerevisiae oxidizes episterol.
== Natural occurrence == The half-life of thorium-232 (14 billion years) is more than three times the age of the Earth; thorium-232 therefore occurs in nature as a primordial nuclide. Other thorium isotopes occur in nature in much smaller quantities as intermediate products in the decay chains of uranium-238, uranium-235, and thorium-232. Some minerals that contain thorium include apatite, sphene, zircon, allanite, monazite, pyrochlore, thorite, and xenotime.
=== No development reported === Atomoxetine/orexin antagonist (AD-182) – combination of atomoxetine (norepinephrine reuptake inhibitor) and an orexin receptor antagonist [24] Daridorexant (ACT-541468; nemorexant; Quviviq) – orexin OX1 and OX2 receptor antagonist [25] Lemborexant (Dayvigo; E-2006; LEM) – orexin OX1 and OX2 receptor antagonist [26] Research programme: AMPA receptor agonists - RespireRx (ampakines; CX compounds) – ampakines (AMPA receptor positive allosteric modulators) and brain-derived neurotrophic factor (BDNF) stimulants [27] Research programme: sleep apnoea therapeutics - Apnimed – undefined mechanism of action [28] Seltorexant (JNJ-42847922; JNJ-7922; MIN-202) – orexin OX2 receptor antagonist [29] Vornorexant (ORN-0829; TS-142) – orexin OX1 and OX2 receptor antagonist [30]
In 2013, Lieutenant colonel Riho Ühtegi wrote: "to this day it is relatively difficult to obtain information about what really happened at any given moment in 2008. [...] Nevertheless, even in June 2008 all the signs showed that even if war were to erupt, it would happen in Abkhazia. [...] The situation changed in June. [...] The Ossetians attacked the Georgian-populated villages in South Ossetia, which was met with Georgian mortar fire from behind the line of control. [...] Indeed, considering the complicated situation in South Caucasus in the summer of 2008, it is difficult to say exactly who started the war. In fact – we should first agree upon how we define starting a war. [...] As far as provocations are concerned, [...] the Russian side or rather the Ossetians with support from the Russian forces conducted a multitude of provocations during the summer of 2008, which led to the war. [...] The Russian analysts were obviously able to assess the international situation adequately and calculated that should Georgia send its regular forces to attack the newly independent South Ossetia and should Russia react to it with a military counterstrike, it would not cause a war between great powers, because first there will be a dispute as to who the aggressor is – Russia or Georgia itself."
Sources: en.wikipedia.org
=== Brand names === Nalbuphine is marketed primarily under the brand names Nubain, Nalpain, and Nalbuphin. It is also marketed under the brand name Nalufin in Egypt and Nalbun in Bangladesh by Incepta Pharma Limited, under the brand name Rubuphine in India by Rusan Healthcare Pvt Ltd, under the brand name Kinz and Nalbin in Pakistan by Sami and Global Pharmaceuticals, under the brand name Analin by Medicaids in Pakistan, and under the brand name Exnal by Indus Pharma in Pakistan, among many others.
In September 2023, SF Holding's sorting and transshipment center located in the Ezhou cargo hub officially began operations. In May 2024, SF Holding submitted a prospectus for a secondary listing in Hong Kong. In the same year, it passed the hearing of the Hong Kong Stock Exchange on November 10 and planned to be listed on the main board of Hong Kong on November 27. The joint sponsors were Goldman Sachs, Huatai International and JPMorgan Chase, making it the first "A+H" listed company in China's logistics industry. In December 2024, SF Holding's H shares were included in the Hong Kong Stock Connect. On March 3, 2025, Kerry Logistics, a subsidiary of SF Holding, announced rebranding in both English and Chinese to KLN Logistics Group Limited. On April 21, 2025, SF Holding's infrastructure public real estate investment trust fund, "China Southern SF Warehousing & Logistics Close-end Infrastructure Fund", was officially listed on the Shenzhen Stock Exchange. On June 25, 2025, SF Holding introduced a new H-shares through its wholly-owned overseas subsidiary on The Stock Exchange of Hong Kong Limited with convertible bonds of HKD 42.15 per share totaling HKD 2.95 billion; the transaction was completed on July 4, 2025, with a total of 70 million (29.2%) new H-shares issued.
Once this was finished, the riggers carefully made their way across the hanging cables, tying the foot-ropes together and connecting the handrails and the foot-ropes with the remainder of the thin grass ropes. Not all rope bridges were exactly alike in terms of design and build. Some riggers also wove pieces of wood into the foot-ropes. Modern-day rope bridge builders in Huinchiri, Peru make offerings to Pacha Mama, otherwise known as "Mother Earth," throughout their building process to ensure that the bridge will be strong and safe. This may have been a practice used by the Inca people since they too were religious. If all went smoothly and if tasks were performed in a timely fashion, a bridge had the potential of being constructed in three days.
The truce between South Africa and Angola survived only about fifteen months. Negotiations for completing the SADF withdrawal were stalled due to intransigence on both sides concerning the linkage policy, with the two governments clashing over timetables for the withdrawal of Cuban troops and Namibian independence, respectively. While the Soviet Union and Cuba did nothing to impede the dialogue, they feared that Luanda might sacrifice PLAN and MK by agreeing to expel them from the country. Castro confided to Soviet officials that he had no intention of authorising a withdrawal of Cuban forces if the Angolan government signed a non-aggression pact with South Africa similar to the Nkomati Accord. As a last resort, the Cuban presence in Angola would be maintained unilaterally for the purpose of aiding PLAN, with or without Luanda's approval. In October 1984, dos Santos blamed South Africa for stalling the implementation of the Lusaka Accords and called for the US to resolve the impasse by exerting pressure on Botha. On 17 November, dos Santos proposed a five-point peace plan on the following terms: a complete SADF withdrawal from Angola, a renewed ceasefire agreement, a formal pledge by the South African government to begin implementing Namibian independence under the terms of United Nations Security Council Resolution 435, a formal pledge by the Angolan government to begin implementing a three year phased withdrawal of all but 5,000 Cuban troops, and recognition of SWAPO and Cuba as an equal party in negotiations.
nucleoplasm Also karyoplasm. All of the material enclosed within the nucleus of a cell by the nuclear envelope, analogous to the cytoplasm enclosed by the main cell membrane. Like the cytoplasm, the nucleoplasm is composed of a gel-like substance (the nucleosol) in which various organelles, nuclear proteins, and other biomolecules are suspended, including nuclear DNA in the form of chromosomes, the nucleolus, nuclear bodies, and free nucleotides.
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.
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.