Everything below concerns sublimation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-04-02. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Process name | Lyophilization or freeze-drying | Both terms appear in technical standards and literature. |
| Phase transition | Sublimation | Solid ice becomes vapor without a liquid step. |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product temperature and equipment. |
| Typical product temperature | -40 °C to -10 °C | Measured during primary drying; formulation sets limits. |
| Water content after drying | 0.5-3% w/w | Target varies by material and stability needs. |
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.
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.
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.
== History == One of the first scientific reports is the colloidal gold particles synthesized by Michael Faraday as early as 1857. By the early 1940's, precipitated and fumed silica nanoparticles were being manufactured and sold in USA and Germany as substitutes for ultrafine carbon black for rubber reinforcements.
=== Names === It is often sold as a salt in the form of either codeine sulfate or codeine phosphate in the United States, United Kingdom, and Australia. Codeine hydrochloride is more common worldwide and the citrate, hydroiodide, hydrobromide, tartrate, and other salts are also seen. The chemical name for codeine is morphinan-6-ol, 7,8-didehydro-4,5-epoxy-3-methoxy-17-methyl-, (5α,6α)-
== History == B-cell activating factor is a naturally occurring protein that was discovered by researchers from National Jewish Health (previously the National Jewish Medical and Research Center) and the University of Colorado, who jointly published a paper detailing their findings in May 1999 and named the protein TALL-1. The same protein was named BAFF in another paper published in June 1999, and in a paper published in July of that year, Human Genome Sciences (HGS) referred to it as BLyS (short for B lymphocyte stimulator). Six years later, research showing the key role of BLyS in B cell differentiation, survival, and activation was published. In October 2000, HGS and Cambridge Antibody Technology (CAT) agreed to co-develop monoclonal antibodies targeted at BLyS. Under this agreement, CAT would identify antibodies and HGS would select appropriate ones to take into clinical trials. In 2003, CAT researchers reported that, by using phage display technology, they had elicited an array of more than 1,000 distinct antibodies, half of which inhibited binding of BLyS to its receptor. Later that year, one of these antibodies was isolated and characterized. It was named LymphoStat-B and subsequently called belimumab. In August 2006, HGS and GlaxoSmithKline (GSK) entered into a co-development and commercialization agreement under which HGS would conduct Phase III trials for belimumab with assistance from GSK. The companies would share equally in Phase III/IV development costs, sales and marketing expenses, and profits of any product commercialized under the agreement.
Ken Levine and other members of Looking Glass Studios founded Irrational Games in 1997. Their first game was System Shock 2, a sequel to Looking Glass's System Shock, and was a critical, but not commercial, success. Levine had attempted to pitch a sequel to System Shock 2 to Electronic Arts, but the publisher rejected the idea based on System Shock 2's disappointing sales. Irrational developed other games, including Freedom Force, Tribes: Vengeance, the canceled title Deep Cover, and The Lost which was never released due to legal complications. The wanted to return to a more free-form game with strong narrative in the same style as System Shock 2, feeling there was more to do with some of the concept of that game. At the same time, they were mindful of making a successor that was more accessible to a wider variety of players. "We recognized that there were things in System Shock 2 that were holding it back, that were excessively complicated, that were opaque or hard for people to understand or that they simply didn't like," Irrational co-founder Jonathan Chey recalled. By 2002, the team had come up with a core gameplay mechanic based on three groups: drones that would carry a desirable resource, protectors that would guard the drones, and harvesters that would attempt to take the resource from the drones. These groups would eventually become the Little Sisters, Big Daddies, and Splicers in the final game. They began working on a setting to pitch the idea to publishers. A 2002 demonstration version was based on the Unreal Engine 2 for the Xbox.
Sources: en.wikipedia.org
Several receptor binding studies have shown that antalarmin and CP-154,526 have high affinity for CRH1 receptors, with very similar profiles. Table 2 shows the binding affinities of each compound in various cell lines.
In 1903, entrepreneur Ernest Woodruff merged three cold storage warehouses to form Atlanta Ice and Coal Company and in 1909 renamed the company Atlantic Ice and Coal as part of a large consolidation of ice and coal companies throughout the eastern states. In 1919, Woodruff bought the Coca-Cola Company from Asa Candler's children for $25,000,000. In 1935, Atlantic Ice & Coal Company changed names to Atlantic Company and began to expand into a variety of different businesses, including cold storage and beer production, the latter contributing up to 50% of the company's revenues at its peak. Atlantic Company diversified into ice convenience store development under the name EZ stores, before household refrigerators were commonplace. It also ran a fast food operation called Wishbone Fried Chicken. Atlantic Company merged with Munford Do it Yourself stores and became Atlantic-Munford, rapidly developing its convenience store growth. The company then merged with Jackson Minit Market and Handy Andy, and was renamed Jackson Atlantic, growing to 40 warehouses in the USA. It was one of the largest warehouse networks at that time. The company went public in 1968 and a few years later merged with United Refrigerated Services. The company then set out to develop the USA's most comprehensive cold storage network. Atlanta became the company's home again in the early 1980s. Acquisitions and mergers continued during the 1980s and 1990s with the company's current name, Americold, appearing in 1997.
In a previous research study, the researchers found that the representation of the "outcast" character with mental illness in a movie tends to get negative evaluations from the children. Regarding this, the study found that it could make the children stick with the significant levels of stigmatization in negatively labeling individuals with mental illness even when they grow up. Other research specifically focused on a particular film, Joker, found that the depiction of individuals with mental illness appears to be negative towards the audience. Regarding this, the researchers demonstrated the concerns that the film Joker could aggravate the self-stigma of individuals with mental illness with an emphasis on negative depictions. Another troubling effect is that stereotypical imagery, coupled with the lack of alternative viewpoints, further dissuades mentally ill people from seeking help or treatment. Due to the generally negative view of mental illnesses, regardless of whether or not it is based on truth, those who experience mental illness often feel dejected, embarrassed, or shameful about their diagnoses. These feelings may lead people with mental illnesses to distance themselves from loved ones and often avoid seeking help or treatment due to fear of rejection.
== Lorch Foundation == ELGA founded the Lorch Foundation in 1979, which subsequently established the School of Water Sciences. Now known as the Cranfield Water Science Institute at Cranfield University, England, it aims to support, encourage and maintain the studies of students interested in water treatment sciences. The aim of the Foundation is to "fund the furtherance of scientific research and education to the benefit of water treatment technology".
Enzymes are crucial to metabolism because they allow organisms to drive reactions that require energy and will not occur by themselves, by coupling them to spontaneous reactions that release energy. Enzymes act as catalysts—they allow a reaction to proceed more rapidly—and they also allow the regulation of the rate of a metabolic reaction, for example, in response to changes in the cell's environment or to signals from other cells. The metabolic system of a particular organism determines which substances it will find nutritious and which poisonous. For example, some prokaryotes use hydrogen sulfide (H₂S) as a nutrient, yet this gas is poisonous to some animals. Since hydrogen sulfide is a gasotransmitter, certain mammals including humans produce H₂S naturally in very small concentrations where it serves vital signaling and regulatory functions. The basal metabolic rate of an organism is the measure of the amount of energy consumed by all of these chemical reactions. A notable feature of metabolism is the similarity of the basic metabolic pathways among vastly different species. For example, the set of carboxylic acids that are best known as the intermediates in the citric acid cycle are present in all known organisms, being found in species as diverse as the unicellular bacterium Escherichia coli (E. coli) and huge multicellular organisms like elephants. These similarities in metabolic pathways are likely due to their early appearance in evolutionary history, and their retention is likely due to their efficacy.
Sources: en.wikipedia.org
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.
Lowering pressure reduces the boiling point of water and allows ice to sublimate at temperatures below freezing. Vacuum also limits convective heat transfer, so heat is usually supplied by shelves or radiation. The pressure must stay below the vapor pressure of ice at the product temperature.
The cycle typically includes freezing, primary drying, and secondary drying. Freezing solidifies water and sets the pore structure; primary drying removes bulk ice; secondary drying removes bound water. Some cycles add annealing or pre-freezing steps.
Lyophilization relies on sublimation, so water moves from solid ice to vapor without becoming liquid. The material is frozen, pressure is reduced, and controlled heat is supplied. Vapor is captured on a cold condenser, leaving a dry porous solid.