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 2026-03-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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. |
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.
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.
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.
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.
=== University of Sheffield === There was little prospect for promotion at Cambridge; Florey hoped that a chair of experimental medicine would be created, but this did not occur until 1945. He collaborated with biochemist Marjory Stephenson on his lysozyme project, but she did not have enough time to spare for a researcher in another department, and their results were not published. He yearned to have an interdisciplinary team and funds for work other than his own. The death of James Sholto Cameron Douglas on 30 October 1931 created a vacancy in the Joseph Hunter chair of pathology at the University of Sheffield, and Florey decided to apply.
=== Halides === Protactinium(V) fluoride is a white compound that forms tetragonal crystals, isomorphic to β-UF5. Protactinium(V) chloride forms yellow crystals where protactinium ions are arranged in pentagonal bipyramids and coordinated by 7 other ions. The coordination changes to octahedral in the brown protactinium(V) bromide, but is unknown for protactinium(V) iodide. The protactinium coordination in all its tetrahalides is 8, but the arrangement is square antiprismatic in protactinium(IV) fluoride and dodecahedral in the chloride and bromide. Brown-colored protactinium(III) iodide has been reported, where protactinium ions are 8-coordinated in a bicapped trigonal prismatic arrangement.
The number of actions needed to get the drug increases every time, so it becomes harder and harder to get the drug. The highest number of actions that the animal or human is willing to do to get the drug is called the break point. The higher the break point, the more the animal or human wants the drug. In contrast to the classical stimulants such as amphetamine, the effects of modafinil depend on what the animals or humans have to do after getting the drug. If they have to do a performance task, like solving a puzzle or remembering something, modafinil makes them work harder for it than placebo, and the subjects wanted to self-administer modafinil. But if they had to do a relaxation task, like listening to music or watching a video, the subjects did not want to self-administer modafinil. This suggests that modafinil is more rewarding when it helps the animals or humans do something better or faster, especially considering that modafinil is not commonly abused or depended on by people, unlike other stimulants.
When their bone density is low, there is a higher risk of microfractures in the vertebrae causing the spine to curve and bend. These curves and bends cause pressure onto the vertebra which could cause progression of scoliosis. When the spine is in this shape, it makes it very difficult for the children to play and exercise. This will also improve the severity of the scoliosis.
=== Charterism === In line with Seekings's latter point, some historians have assigned a central role to the rise of what was known by 1984 as Charterism: adherence to the Freedom Charter, the anti-apartheid political manifesto adopted at the 1955 Congress of the People (and subsequently banned by the apartheid state). After a period of dormancy inside the country while Black Consciousness ideology predominated, Charterism had been revived from around 1979. On some accounts, this revival was partly the result of the interest of young people, and COSAS, certainly, was fiercely Charterist. Although the UDF had not yet formally adopted the Freedom Charter, many of its affiliates and leaders, while usually identifying implicitly with the ANC, identified explicitly with the Charter; and the growth of the UDF contributed to the spread of Charterism. According to Raymond Suttner:A whole generation had grown up without access to literature about the Congress movement. This is not to say that the memory was wiped out, but there was a rupture, organisationally, in terms of symbols and also in the free and widespread diffusion of values. The UDF reconnected people to that tradition...Widespread subscription to the principles of the Freedom Charter, in turn, may have partly inspired the uprising, particularly insofar as the Freedom Charter provided a framework for "linking everyday grievances to aspirations for a new society" or, in other words, for the identification of "the intersection between localised grievances and the strategies and ideology of the ANC".
Sources: en.wikipedia.org
=== Protease === OGT cleaves Host Cell Factor C1, at one or more of 6 repeating 26 amino acid sequences. The TPR domain of OGT binds to the carboxyl terminal portion of an HCF1 proteolytic repeat so that the cleavage region is in the glycosyltransferase active site above uridine-diphosphate-GlcNAc The large proportion of OGT complexed with HCF1 is necessary for HCF1 cleavage, and HCFC1 is required for OGT stabilization in the nucleus. HCF1 regulates OGT stability using a post-transcriptional mechanism, however the mechanism of the interaction with HCFC1 is still unknown.
=== Water treatment === Several destructive and non-destructive technologies can be applied to drinking water supplies, groundwater, industrial wastewater, surface water, and other applications such as landfill leachate, including: Non-destructive methods
Russia claimed to have taken the villages of Hatyshche, Krasne, Morokhovets, and Oliinykove in Kharkiv Oblast. In Russia, the governor of Volgograd Oblast, Andrey Bocharov, claimed that a Ukrainian drone started a fire at an oil refinery, which was put out without any casualties. In Belgorod, officials claimed that 16 people were killed and 27 others were injured when a fragment of a Tochka-U struck an apartment building, according to the Russian Defence Ministry, which also claimed to have shot down several missiles over Belgorod Oblast. Ukrainian media later reported that the HUR carried out drone strikes in Volgograd, Lipetsk and Kaluga Oblasts. One person was killed by Russian shelling in Sumy Oblast. Officials reported that Ukraine's seaborne grain exports had recovered to close to their prewar level. The Kremlin announced the appointment of economist and Deputy Prime Minister Andrey Belousov as Defence Minister, replacing Sergei Shoigu who was transferred to become secretary of the Security Council of Russia.
Therefore, the Royal College of Pathologists and Royal College of Physicians have developed combined infection training, that medical trainees gain a much more patient focused experience, and undertake physician examinations in addition to pathology training. The result of this is that several regional medical deaneries no longer permit medical doctors to train in microbiology or virology as single disciplines, and instead advocate dual-specialisation as infectious disease/microbiology or infectious disease/virology. Simultaneously, the expansion of higher specialist scientist trainees in microbiology means that many of the laboratory and scientific responsibilities of medical doctors may be taken on by clinical scientists, and medical doctors will instead be expected to perform a much more patient facing role. The exception in microbiology is the sub-discipline of virology, which is well suited to the expertise of clinical scientists due to reliance on cutting-edge scientific methods, increasing use of specialised genetic technologies, and a technical understanding of virus biology, with a reduced emphasis on patient management compared with microbiology as a whole.
Sources: en.wikipedia.org
== Etymology == The historical origin of the term is unclear as the definition of the word has changed throughout the past few decades. The term first appeared in a 1984 publication that described the organization of an endothelium-like membrane on the surface of a long-implanted, synthetic ophthalmic prosthesis. The first modern use of the term as recognized today was in 1985 by the researcher, physiologist and bioengineer Yuan-Cheng Fung of the Engineering Research Center. He proposed the joining of the terms tissue (in reference to the fundamental relationship between cells and organs) and engineering (in reference to the field of modification of said tissues). The term was officially adopted in 1987.
== Mold == Mold is a generic term for a specific type of fungi. Mildew may also refer to types of mold. Since there are so many species of mold, their appearance varies in color and growth habit. In general, active mold has a musty odor and appears fuzzy, slimy, or damp. Inactive mold looks dry and powdery. Mold propagates via spores, which are always present in the environment. Mold spores can be transferred to an object by mechanical instruments or air circulation. When spores attach to another organism, and the environment is favorable, they begin to germinate. Mold produce mycelium which growth pattern resembles cobwebs. Mycelium allows the mold to obtain food and nutrients through the host. Inevitably, the mycelium produces spore sacs and release new spores into the air. Eventually the spores land on new material, and the reproductive cycle begins again. Identifying mold can be a challenge, because some species resemble dust, dirt, or spiderwebs. In addition, staining caused by mold can be confused with water damage. Ultraviolet light and magnification are two tools to aid in identifying mold on library collections. Poor air circulation, moisture, high temperatures, and environmental humidity are the main causes of mold outbreaks in library collections. When the temperature is above 70 °F (21 °C) and the relative humidity is above 55 percent, mold begins to develop. Collections kept in basements or environments with uncontrolled temperature and humidity are most likely to be impacted by a mold outbreak.
== Adverse effects == Although ayahuasca is generally safe in traditional use, adverse effects can occur. In the short term, ingesting ayahuasca can cause nausea, vomiting, and diarrhea. These three effects, known as purging, are traditionally recognized to be a part of the spiritual experience of ayahuasca. Physiologically, vomiting may be related to increased serotonergic signaling in the gut, which directly stimulates the vagus nerve. Other short-term side effects include increased blood pressure and tachycardia. Additionally, increased secretion of hormones like prolactin, cortisone, and growth hormone has been correlated with ayahuasca consumption. Rarer side effects include shortness of breath, seizures and serotonin syndrome. Ayahuasca is suspected of triggering psychosis and schizophrenia in people with a predisposition to the condition, and there is a lack of safety information for ayahuasca's possible effects on pregnancy and breastfeeding. A 2024 review found that traditional ayahuasca use is generally safe, but higher doses of ayahuasca or higher doses of isolated harmala alkaloids like harmaline may pose risks.
In a passage describing the challenges of "boiling an egg", for instance, the reader is not given any clue that the original Japanese text discussed a speciality of Kyoto-style cuisine called koya dofu (高野豆腐), a freeze dried tofu dish named after the Koyasan region from which it originates. In contrast to the symbolism of Kyoto-style cuisine as authentic Japanese fare, Tanizaki disparages Kobe as "foreign" including items like liver sausage from a German butcher. Of Tanazaki's characters, Louise, a prostitute involved with Kaname, is the most strongly associated with Kobe fare. Though Misako's consumption of the Kobe style food is alluded to from time to time, Misako herself is more clearly associated with the eastern Japanese fare of Tokyo.
Giant, a subsidiary of Cold Storage, is one of the largest players of the retail industry in Singapore as well as in Malaysia, having over 85 branches spread throughout the country. It was founded by the Teng family in 1944. Prices at Giant are significantly cheaper than at Cold Storage.
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.