If you have been reading about Eutectic temperature and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-10-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common name | Freeze-drying | Process removes water by sublimation under vacuum. |
| Typical primary drying shelf temperature | -40 C to -10 C | Set below the formulation's collapse temperature. |
| Typical chamber pressure | 0.05-0.3 mbar | Low pressure allows ice to sublime below its triple point. |
| Water content after drying | 0.5-3% by weight | Higher values may reduce storage stability for some materials. |
| Key thermal parameter | Collapse temperature | Measured by freeze-drying microscopy or differential scanning calorimetry. |
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.
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.
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.
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.
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.
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.
Freezing determines ice crystal structure and pore size, which affect drying speed and product uniformity. Rapid freezing creates small crystals, while slow freezing creates larger crystals and often faster sublimation. During primary drying, chamber pressure is held below the vapor pressure of ice, and shelf temperature supplies heat for sublimation. The ice front recedes, leaving a porous matrix. Thermal limits such as collapse and eutectic temperatures set safe boundaries for formulation. These limits vary with solute composition and concentration.
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.
"Bad and Boujee" is a song by American hip-hop group Migos featuring American rapper Lil Uzi Vert. Written alongside producer Metro Boomin and co-producer G Koop, it was originally released to the Quality Control Music YouTube channel on August 27, 2016 before being officially released on October 28 by Quality Control Music, 300 Entertainment, and Atlantic Records as the lead single from the group's second studio album Culture (2017). In late December 2016, "Bad and Boujee" became an Internet phenomenon, spawning many memes with the lyrics "rain drop, drop top". This viral trend, combined with Donald Glover's shoutout at the 2017 Golden Globes, would help its commercial performance and cause the song to spike into the top ten and later peak at number one on the US Billboard Hot 100 for the week of January 21, 2017, making it the first number one single for both Migos and Lil Uzi Vert. There were also many memes about member Takeoff's omission from the song. The single received a nomination for Best Rap Performance at the 60th Annual Grammy Awards. The track has acquired over 1 billion Spotify plays as of August 2025.
Anoop's father, who was the Minister for Food and Civil Supplies, died on 30 October 2011. Following this, Anoop was nominated by the Kerala Congress (Jacob) and UDF to contest from the Piravom assembly seat previously represented by his father. His father had lost the sitting seat in 2006 elections and recaptured it in 2011 election by a margin of 157 votes. Against Anoop Jacob, CPI(M)–led LDF once again fielded M. J. Jacob, who had won against T. M. Jacob in 2006 and lost in 2011. Since the result of Piravom by-election mattered heavily to the ruling UDF who had a slender margin of 1 seat in the Legislative assembly over LDF, the constituency witnessed intense campaigning from both sides. Election was held on 17 March 2012 and results were announced on 21 March 2012. Anoop Jacob won the by-election by a significant margin of 12,071 votes. He was sworn in as an MLA on 22 March 2012. Anoop took oath as the Minister for Food & Civil Supplies on 12 April 2012 and occupied office in the North Block of the Kerala Secretariat; both portfolio & office last held by his departed father.
Albiglutide (trade names Eperzan in Europe and Tanzeum in the US) is a glucagon-like peptide-1 agonist (GLP-1 agonist) drug marketed by GlaxoSmithKline (GSK) for treatment of type 2 diabetes. In 2017 GSK announced Albiglutide's withdrawal from the worldwide market for economic reasons, and remaining stocks in the supply chain were effectively depleted by 2018. Albiglutide was used for the treatment of type 2 diabetes in adults. It can be used alone (if metformin therapy is ineffective or not tolerated) or in combination with other antidiabetic drugs, including insulins. According to a 2015 analysis, albiglutide is less effective than other GLP-1 agonists for lowering glycated hemoglobin (HbA1c, an indicator for long-term blood glucose control) and weight loss. It also seems to have fewer side effects than most other drugs of this class, except for reactions at the injection site which are more common under albiglutide than, for example, under liraglutide.
Aldo Carl Leopold (December 18, 1919 – November 18, 2009) was an American academic and plant physiologist, son of Aldo Leopold, a noted ecologist. He is known for his research on soybeans which led to techniques allowing insulin to be dried and later processed into an inhalable insulin. Aldo Carl Leopold was born to Aldo Leopold, a noted ecologist and employee of the United States Forest Service, and Estella Leopold in Albuquerque, New Mexico as the 4th of 5 children.
ALK-negative ALCL tumor cells show products made by chimeric genes: DUSP22-IRF4 (many of which are fused at particular site and termed DUSP22-FRA7H) in 30% of the cases; TP63-TBL1XR1 in 8% of cases; and NFKB2-ROS1, NCOR2-ROS1, NFKB2-TYK2, or PABPC4-TYK2 in rare cases. They also show mutations in the JAK1 and/or STAT3 genes in 18% of cases; the MSC gene in 15% of cases, and the NOTCH1 gene in 15% of cases. About 24% of cases have a truncated ERBB4 gene. DUSP22 gene rearrangements have been associated with favorable outcomes in ALK-negative ALCL while TP63 gene arrangements are often associated with a poorer prognosis in various cancers. ALK-negative ALCL cells overexpress overactive STAT3 in 47% of cases and JAK1 in many cases. Many of these gene abnormalities appear to contribute to the development of ALK-negative ALCL.
Sources: en.wikipedia.org
In 1955, a USAF surgeon who advised the US Surgeon General wrote an article on how to make cars safer for those riding in it. Aside from the usual safety features, such as seat belts and padded dashboards, bumper shocks were introduced. In 1956, Ford tried unsuccessfully to interest Americans in purchasing safer cars with their Lifeguard safety package. (Its attempt nevertheless earns Ford Motor Trend's "Car of the Year" award for 1956.) In 1958, the United Nations established the World Forum for Harmonization of Vehicle Regulations, an international standards body advancing auto safety. Many of the most life saving safety innovations, like seat belts and roll cage construction were brought to market under its auspices. That same year, Volvo engineer Nils Bohlin invented and patented the three-point lap and shoulder seat belt, which became standard equipment on all Volvo cars in 1959. Over the next several decades, three-point safety belts were gradually mandated in all vehicles by regulators throughout the industrialised world. In 1959, American Motors Corporation offered the first optional head rests for the front seat. Also in 1959, the Cadillac Cyclone concept by Harley Earl had "a radar-based crash-avoidance system" located on the nose cones of the vehicle that would make audible and visual signals to the driver if there were obstacles in the vehicle's path.
Biological precursors of most alkaloids are amino acids, such as ornithine, lysine, phenylalanine, tyrosine, tryptophan, histidine, aspartic acid, and anthranilic acid. Nicotinic acid can be synthesized from tryptophan or aspartic acid. Ways of alkaloid biosynthesis are too numerous and cannot be easily classified. However, there are a few typical reactions involved in the biosynthesis of various classes of alkaloids, including synthesis of Schiff bases and Mannich reaction. Schiff bases can be obtained by reacting amines with ketones or aldehydes. These reactions are a common method of producing C=N bonds. In the biosynthesis of alkaloids, such reactions may take place within a molecule, such as in the synthesis of piperidine: An integral component of the Mannich reaction, in addition to an amine and a carbonyl compound, is a carbanion, which plays the role of the nucleophile in the nucleophilic addition to the ion formed by the reaction of the amine and the carbonyl. The Mannich reaction can proceed both intermolecularly and intramolecularly:
Aberrant activation of Akt, either via PI3K or independently of PI3K, is often associated with malignancy. Studies have identified gene amplification of the Akt isoforms in many types of cancer, including glioblastoma, ovarian, pancreatic and breast cancers. Akt is also up-regulated in terms of mRNA production in breast and prostate cancer. Functional inactivation of PTEN, the major PI3K antagonist, can occur in cancer cells by point mutation, gene deletion or epigenetic mechanisms. Mutation in the pathway can also affect receptor tyrosine kinases, growth factors, Ras and the PI3K p110 subunit, leading to abnormal signaling activity. Therefore, many of the proteins in the pathway are targets for cancer therapeutics. In addition to its effects on cell survival and cell cycle progression, the PI3K-Akt pathway promotes other characteristics of cancer cells. Hyperactivity of the pathway promotes the epithelial-mesenchymal transition (EMT) and metastasis due to its effects on cell migration.
Binding of a ligand to a binding site on protein often triggers a change in conformation in the protein and results in altered cellular function. Hence binding site on protein are critical parts of signal transduction pathways. Types of ligands include neurotransmitters, toxins, neuropeptides, and steroid hormones. Binding sites incur functional changes in a number of contexts, including enzyme catalysis, molecular pathway signaling, homeostatic regulation, and physiological function. Electric charge, steric shape and geometry of the site selectively allow for highly specific ligands to bind, activating a particular cascade of cellular interactions the protein is responsible for.
Sources: en.wikipedia.org
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.
Freezing determines ice crystal size, pore structure, and the concentration of solutes in remaining liquid. Faster freezing generally creates smaller ice crystals and a denser dried matrix. These features affect drying rate and reconstitution behavior.
Lyophilization reduces water content but usually leaves a small amount of water in the dried material. Some water remains bound to solids or trapped in the dried matrix. Very low water targets can require extended secondary drying, which may alter product stability.
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.