moisture content is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-07-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Stability of a lyophilized product depends on its glass transition temperature, the temperature at which the amorphous cake transitions from a glassy to a rubbery state. Storage below this temperature minimizes molecular mobility and slows chemical degradation. If the storage temperature exceeds the glass transition temperature, the cake may collapse, shrink, or become sticky. Accelerated stability studies at elevated temperatures and humidity help predict shelf life, but they do not always reflect real-time behavior. Residual moisture content also plays a critical role in long-term stability.
Reconstitution involves adding a suitable diluent, often sterile water or a buffer, to the dried cake. Gentle swirling or inversion helps dissolve the material without creating excessive foam. The time required for complete dissolution can range from seconds to several minutes and depends on the cake structure and the diluent. Improper reconstitution, such as vigorous shaking or using the wrong diluent, can cause protein aggregation or loss of activity. After reconstitution, the product may have a limited shelf life and should be used according to its labeling.
| 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. |
=== Chromatography === Internal standards are used in GC/MS and LC/MS to control for variability introduced by injection, sample preparation and other matrix effects. The ratio of peak areas between the internal standard and analyte is calculated to determine analyte concentration. A common type of internal standard is an isotopically labeled analogue of the analyte, which incorporates one or more atoms of 2H, 13C, 15N and 18O into its structure.
== Preparation and manufacturing == The simplest method for preparing ceramic superconductors is a solid-state thermochemical reaction involving mixing, calcination and sintering. The appropriate amounts of precursor powders, usually oxides and carbonates, are mixed thoroughly using a Ball mill. Solution chemistry processes such as coprecipitation, freeze-drying and sol–gel methods are alternative ways for preparing a homogeneous mixture. These powders are calcined in the temperature range from 1,070 to 1,220 K (800 to 950 °C) for several hours. The powders are cooled, reground and calcined again. This process is repeated several times to get homogeneous material. The powders are subsequently compacted to pellets and sintered. The sintering environment such as temperature, annealing time, atmosphere and cooling rate play a very important role in getting good high-Tc superconducting materials. The YBa2Cu3O7−x compound is prepared by calcination and sintering of a homogeneous mixture of Y2O3, BaCO3 and CuO in the appropriate atomic ratio. Calcination is done at 1,070 to 1,220 K (800 to 950 °C), whereas sintering is done at 1,220 K (950 °C) in an oxygen atmosphere. The oxygen stoichiometry in this material is very crucial for obtaining a superconducting YBa2Cu3O7−x compound. At the time of sintering, the semiconducting tetragonal YBa2Cu3O6 compound is formed, which, on slow cooling in oxygen atmosphere, turns into superconducting YBa2Cu3O7−x. The uptake and loss of oxygen are reversible in YBa2Cu3O7−x.
=== Function of glucagon === While insulin is secreted by the pancreas to lower blood glucose levels, glucagon is secreted to raise blood glucose levels. This is why glucagon has been known for decades as a counter-regulatory hormone. When blood glucose levels are low, the pancreas secretes glucagon, which in turn causes the liver to convert stored glycogen polymers into glucose monomers, which is then released into the blood. This process is called glycogenolysis. Liver cells, or hepatocytes, have glucagon receptors which allow for glucagon to attach to them and thus stimulate glycogenolysis. Contrary to insulin, which is produced by pancreatic β-cells, glucagon is produced by pancreatic α-cells. It is also known that an increase in insulin suppresses glucagon secretion, and a decrease in insulin, along with low glucose levels, stimulates the secretion of glucagon.
=== Veterinary use === The use of progesterone tests in dog breeding to pinpoint ovulation is becoming more widely used. There are several tests available, the most reliable being a blood test with the blood sample drawn by a veterinarian and sent to a lab for processing. Results can usually be obtained within 24 to 72 hours. The rationale for using progesterone tests is that increased numbers begin close to the preovulatory surge in gonadotrophins and continue through ovulation and estrus. When progesterone levels reach certain levels they can signal the stage of estrus the female is. Prediction of birth date of the pending litter can be accurate if ovulation date is known. Puppies deliver within a day or two of nine weeks gestation in most cases. Determining pregnancy using progesterone tests once a breeding has taken place is not possible, however. This limitation is due to the fact that, in dogs, progesterone levels remain elevated throughout the estrus period.
Sources: en.wikipedia.org
== History == Colonies of B. cereus were originally isolated by Percy F. Frankland from a gelatine plate left exposed to the air in a cow shed in 1887. In the 2010s, examination of warning letters issued by the US Food and Drug Administration issued to pharmaceutical manufacturing facilities addressing facility microbial contamination revealed that the most common contaminant was B. cereus. Several new enzymes have been discovered in B. cereus, such as AlkC and AlkD, both of which are involved in DNA repair.
In December 2018, Collins took part in a one-off celebrity special of All Together Now. Collins first performed "Big Spender" by Shirley Bassey where she received a score of 88 after impressing the judges with her vocal ability, which secured her a place in the top 3. She then sang "This Is Me" by Keala Settle and The Greatest Showman ensemble and subsequently finished in third place with a score of 39. Between January and February 2019, Collins took part in the eleventh series of the ITV skating competition Dancing on Ice, alongside professional partner Matt Evers. Her debut performance saw her skate to "Crazy in Love" by Beyoncé, in which she performed the splits on ice and attempted to lift her partner Evers at the end of the routine. She scored 16.0 out of 40.0 points, ultimately receiving the most votes from the public and got through to the next week, with 28.23% of the vote. Following her performance to "Diamonds Are a Girl's Best Friend" in Musicals Week, in which Collins was dressed as Marilyn Monroe and concluded with her being suspended in the air on a giant diamond ring, saw the couple receive 13.0 out of 40.0, the lowest marks of that year's series. Collins subsequently had an on-screen argument with judge Jason Gardiner, who made comments about her weight and lack of commitment to the series, and accused him of selling stories about her to the press.
=== How does dentinal bonding occur? === Dentin bonding refers to process of bonding a resin to conditioned dentin, where mineral component is replaced with resin monomers to form a biocomposite comprising dentin collagen and cured resin. The adhesive-dentin interface forms a tight and permanent bond between dentin and composite resins. It can be accomplished by either etch-and-rinse (total etch) or self-etch adhesives. In etch-and rinse, acid will dissolve the minerals to a certain depth and leaves the highly porous dentinal collagen network suspended in water. Then, the collagen network is infiltrated with resin monomers. After chemical polymerization of these monomers happen, activated by light cure, it will result in a polymer-collagen biocomposite, commonly known as the hybrid layer:
Replacing the methyl ester on the long chain with a tert-butyl ester makes the remifentanil analogue 150,000 times more potent than morphine and 210 times more potent than remifentanil itself, which makes it one of the most potent fentanyl analogues known. The tert-butyl group also makes it more resistant to hydrolysis and extends its half-life in the body.
=== Pets === In 1979, the Van Houweling Research Laboratory of the Silliman University Medical Center in Dumaguete in the Philippines developed and produced a dog vaccine that gave a three-year immunity from rabies. The development of the vaccine resulted in the elimination of rabies in many parts of the Visayas and Mindanao Islands. The successful program in the Philippines was later used as a model by other countries, such as Ecuador and the Mexican state of Yucatán, in their fight against rabies conducted in collaboration with the World Health Organization. In Tunisia, a rabies control program was initiated to give dog owners free of charge vaccination to promote mass vaccination which was sponsored by their government. The vaccine is known as Rabisin (Mérial), which is a cell based rabies vaccine only used countrywide. Vaccinations are often administered when owners take in their dogs for check-ups and visits at the vet. Oral rabies vaccines (see below for details) have been trialled on feral/stray dogs in some areas with high rabies incidence, as it could potentially be more efficient than catching and injecting them. However these have not been deployed for dogs at large scale yet.
Sources: en.wikipedia.org
Liu Wenhui's role in the Long March is described differently by various sources. According to one account, during the fight with Communist forces while the Long March was in process, Chiang Kai-shek repeatedly ordered Liu to bring his troops against the Communists, but Liu made excuses, while secretly allowing safe passage for the Chinese Red Army in a non-aggression pact. Thus, the engagements around Xiakou Village in 1934 did not involve Liu's 24th Army, but the 21st Army of KMT troops garrisoned just across the Sichuan border in Mingshan. However, a contradictory account of his engagement with the Communists is given by the communist-aligned Guangming Daily, which states that during May 1935 Liu Wenhui was supposedly forced by Chiang Kai-shek to oversee the battle with the Red Army at Hanyuan. Liu's 24th Army suffered heavy losses during the battles of Dadu River and Luding Bridge. Another report in his 1990 biography, also written in mainland China by the communist revolutionaries Peng and Shu, instead states that in May 1935 Chiang ordered Liu, as well as general Li Yunheng (李韞珩) of the 16th Army, to block the communist advance. Li's army had stationed at Kangding, and Li supposedly had ambitions to replace Liu's role as head of Xikang. To avoid expending his forces, Liu had his army stage a battle with the communists, firing into the air when necessary and faking reports to Chiang, letting the Red Army pass through Luding Bridge with minimal engagement.
=== American Cancer Society === Inhorn's ongoing interest in cervical cancer was the reason that he joined the American Cancer Society, Wisconsin Division, in 1967. He was Chair of the State Cancer Prevention Study II, and in 1986, he headed a demonstration project with a number of Wisconsin hospitals to determine the acceptance of offering low-cost mammography as a screening test for breast cancer. Inhorn served as President of the Wisconsin Division from 1970 to 1972, continuing on the board until 2010. He also served on the national American Cancer Society Board from 1982 to 1990.
The localisation of the vestibular binding site, as the primary SSRI binding site in SERT is, is however controversial since some research has shown that the SSRIs work in competitive manner by binding to the drugs binding site, not to the second binding site.
== Tailored vaccination strategies == During a pandemic wave, rapid vaccination of those driving virus dissemination (the socially active) and vaccination of those at highest risk (the elderly, often socially less active) are two desirable goals that are at odds in the setting of limited vaccine supply. However, the recent study (published in 2022) on the national COVID-19 vaccination schedules in 29 countries (EU, UK, and Israel) shows that all researched schedules prioritized criteria referring to higher risk (being over 65 years old and/or having coexisting health conditions) over the criteria referring to virus dissemination (occupation and/or housing conditions). Postponing a second vaccine dose (the first is more important for avoiding a severe disease course) to allow faster access to the first dose for more persons has been chosen as deployment strategies in some countries. Using a reduced mRNA vaccine dose in the younger, who have a lower disease risk, a stronger immune response to the vaccination but are key drivers of pandemic waves, may allow reaching more persons faster, with vaccination strategy models predicting a significant reduction of nation-wide case load and deaths. On the other side, protection of some groups, e.g. the elderly or the immunosuppressed may require additional booster doses.
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.
Lyophilized products should be stored in airtight containers, protected from moisture and light, at the temperature specified by the manufacturer. Many require refrigeration at 2–8 °C, while some need frozen storage. Always check the product label for specific conditions.