Everything below concerns primary drying. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
| Property | Value | Notes |
|---|---|---|
| Common name | Freeze-drying | Lyophilization is the technical synonym. |
| Typical chamber pressure | 0.01–0.1 mbar | Below the triple point of water. |
| Primary drying temperature | −40 to −10 °C | Depends on formulation and equipment. |
| Residual moisture | 1–5% | Target for many pharmaceutical products. |
| Typical equipment | Vacuum freeze-dryer | Includes drying chamber and condenser. |
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.
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.
With intrinsic aging, dermal atrophy results from a combination of collagen loss, degeneration of the elastic fiber network, and reduced hydration; chronic ultraviolet exposure further disorganizes both collagen and elastic fibers, a process associated with photoaging and solar elastosis. While collagen provides tensile strength, elastin is primarily responsible for the skin's ability to stretch and recoil, and age-related loss of skin elasticity is more closely linked to a decline in elastin than to collagen loss — making care for elastin an important part of addressing skin laxity and firmness. It strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form. It may be one of the most abundant proteins in the fossil record, given that it appears to fossilize frequently, even in bones from the Mesozoic and Paleozoic. Skin aging involves changes in the extracellular matrix rather than changes in collagen alone. Intrinsic aging is associated with dermal thinning, loss and alteration of collagen, degeneration of the elastic fiber network, and reduced hydration. Chronic ultraviolet exposure further alters the organization of dermal collagen and elastic fibers, producing characteristic changes associated with photoaging. Because collagen and elastin contribute different mechanical properties to the dermal extracellular matrix, preservation of both networks is important for maintaining skin structure and elasticity.
Though virtually unseen in nature, high-purity bismuth can form distinctive, colorful hopper crystals. It is relatively nontoxic and has a low melting point just above 271 °C (520 °F), so crystals may be grown using a household stove, although the resulting crystals tend to be of lower quality than laboratory-grown crystals. At ambient conditions, bismuth shares the same layered structure as the metallic forms of arsenic and antimony, crystallizing in the rhombohedral lattice. When compressed at room temperature, this Bi–I structure changes first to the monoclinic Bi-II at 2.55 GPa, then to the tetragonal Bi-III at 2.7 GPa, and finally to the body-centered cubic Bi-V at 7.7 GPa. The corresponding transitions can be monitored via changes in electrical conductivity; they are rather reproducible and abrupt, so are used for calibration of high-pressure equipment.
Dapagliflozin Canagliflozin Empagliflozin Remogliflozin The side effects of SGLT2 inhibitors are derived directly from their mechanism of action; these include an increased risk of: ketoacidosis, urinary tract infections, candidal vulvovaginitis, and hypoglycemia.
===== Iguania ===== Clade Acrodonta Family Agamidae Pogona vitticeps, Central bearded dragon, (2015) Clade Pleurodonta Family Dactyloidae Anolis carolinensis, Carolina anole, (2011) Family Phrynosomatidae Phrynosoma platyrhinos, Dessert horned lizard, (2021) Phrynosoma cornutum, Texas horned lizard, (2021) Sceloporus undulatus, Eastern fence lizard (2021)
Myiasis is prevalent in livestock, and especially in domestic sheep. Myiasis in sheep is often caused by blowflies (Lucilia sericata and L. cuprina in particular) and is commonly referred to as blowfly strike. Blowfly strike, and other flystrike, occurs worldwide but is most common in regions where hot and wet conditions are sustained, such as Sub-Saharan Africa, Southeast Asia, Latin America, Australia, and New Zealand. As of 2021, blowfly strike accounts for over A$280 million a year in losses for the Australian sheep industry. As mitigation, Australian sheep farmers may engage in mulesing, a procedure designed to remove strips of wool-producing skin that are the most common targets for flies. Farmers may also dock lambs' tails to reduce the likelihood of infestation. However, both mulesing and tail-docking have received criticism from animal welfare groups, who say the mitigative procedures are excessive and can have other negative effects. In addition to blowfly strike in sheep, myiasis from screwworm flies (Cochliomyia hominivorax in particular) regularly cause upwards of US$100 million in annual damages to domestic cows and goats. Screwworm-related myiasis is primarily mitigated through the sterile insect technique.
Sources: en.wikipedia.org
== Sources == This article incorporates text from a publication now in the public domain: Wiriath, Paul (1911). "France: History". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 10 (11th ed.). Cambridge University Press. pp. 867–869.
Prince Harry becomes the first senior member of the British royal family to give evidence in a court case in more than 130 years when he appears at the High Court to give evidence in his case against Mirror Group Newspapers. The Advertising Standards Authority bans a 2022 campaign by Shell plc for being "likely to mislead" consumers. 7 June Figures produced by Halifax Bank indicate house prices have dropped by 1% compared to 2022, the first such fall since 2012. It is announced that The Daily Telegraph and Sunday Telegraph, as well as The Spectator, are to be put up for sale to recover debts incurred by the publications' parent company. 8 June Prime Minister Rishi Sunak holds a joint press conference with US president Joe Biden at the White House to announce the Atlantic Declaration, an agreement to strengthen economic ties between the UK and US. Caroline Lucas, the Green Party's former leader and only MP, announces that she is stepping down from Parliament at the next election. 9 June The UK government announces that the planned windfall tax on oil and gas companies will be suspended if prices return to normal levels for a sustained period. Nadine Dorries announces she will stand down as Conservative MP for Mid Bedfordshire with immediate effect, triggering a by-election. On 14 June 2023 she said that she had submitted a subject access request to the House of Lords Appointments Commission (HOLAC) and was waiting to resign until she had received all unredacted "WhatsApps, text messages, all emails and minutes of meetings" related to why she was denied a peerage.
ATPases (EC 3.6.1.3, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, ATP hydrolase, adenosine triphosphatase) are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion or the inverse reaction. This dephosphorylation reaction releases energy, which the enzyme (in most cases) harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life. Some such enzymes are integral membrane proteins (anchored within biological membranes), and move solutes across the membrane, typically against their concentration gradient. These are called transmembrane ATPases.
=== tip-tis === tipapkinogene sovacivec (INN) tipelukast (USAN) tipentosin (INN) tipepidine (INN) tipetropium bromide (INN) tipifarnib (USAN) tipindole (INN) tiplasinin (USAN) tiplimotide (INN) tipredane (INN) tiprelestat (INN) tiprenolol (INN) tiprinast (INN) tiprolisant (USAN) tipropidil (INN) tiprostanide (INN) tiprotimod (INN) TipTapToe tiqueside (INN) tiquinamide (INN) tiquizium bromide (INN) tiracizine (INN) tirapazamine (INN) tiratricol (INN) tirilazad (INN) tirofiban (INN) tiropramide (INN) tirzepatide (INN) Tis-U-Sol tisagenlecleucel (USAN, INN) Tiseb Tisit tislelizumab (INN) tisocalcitate (USAN) tisocromide (INN) tisopurine (INN) tisoquone (INN) Tissueblue Titralac
Sources: en.wikipedia.org
Conventional drying uses heat to evaporate water from a material, while lyophilization freezes the material and removes water by sublimation under vacuum. This avoids the liquid phase and reduces thermal damage to sensitive substances. The result is a porous cake that reconstitutes quickly.
A vacuum lowers the pressure below the triple point of water, allowing ice to sublimate directly into vapor without melting. It also removes water vapor from the product chamber and speeds up the drying process. Without vacuum, the ice would melt rather than sublimate.
Not all substances are suitable for lyophilization. Materials must form a stable frozen matrix and tolerate freezing and low pressure. Some small molecules, oils, or volatile compounds may not form a proper cake or may be lost during processing.
Conventional drying uses heat to evaporate liquid water, often at temperatures that can degrade sensitive materials. Lyophilization freezes the material first and then removes water by sublimation under vacuum. This avoids prolonged exposure to liquid water and high heat.