A practical reference on glass transition: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-02-24. Anything still debated is marked as such rather than presented as settled.
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.
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.
Misconceptions about lyophilization include the idea that dried products are indefinitely stable or that vacuum sealing eliminates all degradation. Chemical reactions can continue in the solid state, and some proteins lose activity even at low moisture. Another misconception is that any freeze-dryer cycle can be scaled by time alone; heat and mass transfer differ with equipment and load. Open questions remain about predicting long-term stability from short accelerated studies, particularly for amorphous formulations. Real-time stability data remain the standard for shelf-life assignment.
After lyophilization, the dried product is often sealed under vacuum or an inert gas to limit moisture and oxygen exposure. Vials, stoppers, and seals must maintain their barrier throughout shelf life. Storage temperature depends on product sensitivity: some cakes tolerate controlled room temperature, while labile biologics require refrigeration. Humidity is a critical variable because dried cakes are hygroscopic and can absorb water when exposed to air. Handling procedures therefore limit open-vial time and use desiccated environments for sampling.
Quality control for lyophilized materials examines appearance, reconstitution time, residual moisture, and mechanical integrity. An acceptable cake is usually uniform and porous, though appearance alone does not prove stability. Karl Fischer titration is a common method for water content, while differential scanning calorimetry can reveal glass transition events. Stability studies track potency, aggregation, and moisture over time under defined temperature and humidity conditions. Specifications are product-specific and may include sterility and endotoxin tests for sterile preparations.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | freeze-drying, lyophilisation, cryodesiccation | Lyophilization is common in pharmaceutical literature. |
| Typical chamber pressure during primary drying | 0.05–0.5 mbar (5–50 Pa) | Must remain below the triple point of water. |
| Typical shelf temperature during freezing | −40 to −20 °C | Lower temperatures may be used for eutectic systems. |
| Typical residual moisture after secondary drying | 0.5–3% w/w | Product-dependent; low moisture improves stability but can cause over-drying. |
| Typical analytical method for residual moisture | Karl Fischer titration or loss on drying | Thermogravimetric methods are also used. |
A typical cycle begins with freezing, which fixes the material into a solid and determines ice crystal size. Primary drying then raises heat under vacuum so ice sublimes, often near or below the collapse temperature of the formulation. Secondary drying removes bound water that remains after ice is gone, usually by gently warming the product. Each stage balances heat input against pressure to avoid melting or structural damage. Temperature probes and pressure sensors guide the transition between stages.
In practice, lyophilization is slower and more energy intensive than simple drying. Cycle times can range from hours to several days depending on load, container, and formulation. Amorphous materials may require excipients that help preserve structure during freezing and drying. The method is widely used for biological materials, pharmaceuticals, and foods where heat drying would cause unacceptable change. Open questions remain about scaling cycles between laboratory and production equipment, and this gap affects technology transfer.
Lyophilization removes water by freezing a material and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intermediate liquid state. Because the material remains frozen during primary drying, the structure often stays porous. This porous matrix can rehydrate quickly when water is added back. The low pressure also allows vapor to leave the solid matrix without boiling.
After drying, a lyophilized product is usually sealed under vacuum or an inert gas to limit moisture and oxygen exposure. The container closure system matters because stoppers and seals can allow moisture ingress over time. Storage conditions are selected from stability studies that track potency, cake appearance, and reconstitution behavior. Many freeze-dried materials are kept at controlled room temperature, while some require refrigeration or protection from light.
Quality control for freeze-dried forms includes visual inspection, water content measurement, and reconstitution time. A satisfactory cake is typically uniform, porous, and intact, although minor shrinkage or cracking may be acceptable if specifications allow. Karl Fischer titration, thermal gravimetric analysis, and near-infrared spectroscopy are used to measure water content. Reconstitution is assessed by adding a specified diluent and recording the time and ease of dissolution. Microbiological and particulate tests are added when the product is sterile or intended for injection.
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.
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.
Lyophilized products are typically hygroscopic and require protection from moisture during storage. Manufacturers seal them in glass vials, often under vacuum or an inert gas such as nitrogen. The container closure system, including the stopper and crimp seal, must prevent water vapor ingress. Storage temperature varies from controlled room temperature to refrigerated or frozen conditions, depending on the formulation. Humidity-controlled environments are essential because even brief exposure to ambient air can degrade the product.
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.
Campbeltown, a small western coastal town, was once home to over 30 distilleries but now has only three in operation: Glen Scotia, Glengyle, and Springbank. Characteristics vary, but in general, the whiskies are described as "fruity, peaty, sweet, smoky" by the national tourist board; another source published by a marketing company also mentions the "flavor of wet dog, also called wet wool". The Highlands: The Highlands is by far the largest region in Scotland both in area and in whisky production. This massive area has over 30 distilleries on the mainland. Region characteristics: "fruity, sweet, spicy, malty", according to the national tourist board. When the Islands sub-region is included, the total number of distilleries is 47. Some Highland distilleries: Fettercairn, Aberfeldy, Edradour, Balblair, Ben Nevis, Dalmore, Glen Ord, Glenmorangie, Oban, Glendronach, Old Pulteney, Tullibardine and Tomatin. The Islands, an unrecognised sub-region of the Highlands, includes all of the whisky-producing islands other than Islay: Arran, Jura, Mull, Orkney, Raasay and Skye: with their respective distilleries: Arran, Jura, Highland Park, Scapa, Raasay, Talisker and Tobermory. Islay : has nine producing distilleries: Ardbeg, Ardnahoe (the most recent), Bowmore (the oldest, having opened in 1779), Bruichladdich, Bunnahabhain, Caol Ila, Kilchoman, Lagavulin, and Laphroaig. Region Characteristics: distilleries in the south make whisky which is "medium-bodied ... saturated with peat-smoke, brine and iodine" because they use malt that is heavy with peat as well as peaty water.
=== Source Dedicated Server === The Source Dedicated Server (SRCDS) is a standalone launcher for the Source engine that runs multiplayer game sessions without requiring a client. It can be launched through Windows or Linux and can allow for custom levels and assets. Most third-party servers additionally run Metamod:Source and SourceMod, which together provide a framework on top of SRCDS for custom modification of gameplay on existing titles.
To determine this percentage of isotopic exchange, which varies according to local humidity levels, standards of metabolically inert tissue from the species of interest can be constructed and equilibriated to local conditions. This allows measured δD from different regions to be compared against each other.
== Mutations == Mutations in genes encoding uniporters lead to dysfunctional transporter proteins being formed. This loss of function in uniporters causes disruption in cellular function which leads to various diseases and disorders.
Many metering pumps are piston-driven. Piston pumps are positive displacement pumps which can be designed to pump at practically constant flow rates (averaged over time) against a wide range of discharge pressure, including high discharge pressures of thousands of psi. Piston-driven metering pumps commonly work as follows: There is a piston (sometimes called plunger), typically cylindrical, which can go in and out of a correspondingly shaped chamber in the pump head. The inlet and outlet lines are joined to the piston chamber. There are two check valves, often ball check valves, attached to the pump head, one at the inlet line and the other at the outlet line. The inlet valve allows flow from the inlet line to the piston chamber, but not in the reverse direction. The outlet valve allows flow from the chamber to the outlet line, but not in reverse. The motor repeatedly moves the piston into and out of the piston chamber, causing the volume of the chamber to repeatedly become smaller and larger. When the piston moves out, a vacuum is created. Low pressure in the chamber causes liquid to enter and fill the chamber through the inlet check valve, but higher pressure at the outlet causes the outlet valve to shut. Then when the piston moves in, it pressurizes the liquid in the chamber. High pressure in the chamber causes the inlet valve to shut and forces the outlet valve to open, forcing liquid out at the outlet. These alternating suction and discharge strokes are repeated over and over to meter the liquid.
Sources: en.wikipedia.org
Patrick Ryder (born 14 March 1988) is a former Australian rules footballer who played for the Essendon, Port Adelaide and St Kilda Football Clubs in the Australian Football League (AFL). Ryder was noted for his speed, agility and leap for someone of his size and it was these attributes that had his first AFL coach in Kevin Sheedy comparing him to Indigenous Australian rules football star Graham "Polly" Farmer. Ryder's father, Revis Ryder, played football for East Fremantle.
=== Europe === The U.S. market is being eclipsed by booming demand for cocaine in Europe, where users now pay twice the going U.S. rate. In 2008, U.S. Attorney General Michael Mukasey announced that an international drug interdiction operation, Project Reckoning, involving law enforcement in the United States, Italy, Canada, Mexico and Guatemala had netted more than 500 organized crime members involved in the cocaine trade. The announcement highlighted the Italian-Mexican cocaine connection. Concerns about European security and the trafficking of drugs through the European continent have grown in recent years, and, in December 2022, Europol and the DEA released a joint report on the situation involving Mexican drug trafficking through the EU. In December 2011, the government of Spain remarked that Mexican cartels had multiplied their operations in that country, becoming the main entry point of cocaine into Europe. In 2012, it was reported that Mexican cartels had joined forces with the Sicilian Mafia, when Italian officials unearthed information that Palermo's black market, along with other Italian ports, was used by Mexico's drug cartels as a conduit to bring drugs to the European market, in which they had been trafficking drugs, particularly cocaine, throughout the Atlantic Ocean for over ten years to Europe.
Since lithium-ion batteries are intercalation batteries, information on the chemistry and electronic structure going on in the bulk during operation are of interest. For this, soft x-ray information can be obtained using hard X-ray Raman scattering. Fixed energy methods (FEXRAV) have been developed and applied to the study of the catalytic cycle for the oxygen evolution reaction on iridium oxide. FEXRAV consists of recording the absorption coefficient at a fixed energy while varying at will the electrode potential in an electrochemical cell during the course of an electrochemical reaction. It allows to obtain a rapid screening of several systems under different experimental conditions (e.g., nature of the electrolyte, potential window), preliminary to deeper XAS experiments. The soft X-Ray regime (i.e. with photon energy < 1000 eV) can be profitably used for investigating heterogeneous solid-gas reaction. In this case, it is proved that XAS can be sensitive both to the gas phase and to the solid surface states.
Cryogenic cooling of devices and material is usually achieved via the use of liquid nitrogen, liquid helium, or a mechanical cryocooler (which uses high-pressure helium lines). Gifford-McMahon cryocoolers, pulse tube cryocoolers and Stirling cryocoolers are in wide use with selection based on required base temperature and cooling capacity. The most recent development in cryogenics is the use of magnets as regenerators as well as refrigerators. These devices work on the principle known as the magnetocaloric effect.
Sources: en.wikipedia.org
Sericin is a protein created by Bombyx mori (silkworms) in the production of silk. Silk is a fibre produced by the silkworm in production of its cocoon. It consists mainly of two proteins, fibroin and sericin. Silk consists of 70–80% fibroin and 20–30% sericin; fibroin being the structural center of the silk, and sericin being the gum coating the fibres and allowing them to stick to each other.
The Crossbell arc consists of two games. They are set in Crossbell, a city-state located between the great powers of Erebonia and Calvard. It follows rookie police investigator Lloyd Bannings and the Special Support Section, consisting of himself, Elie McDowell, Randy Orlando, and Tio Plato, as they protect the city from criminal activity and the geopolitical situation that looms over it. The first game, Trails from Zero, was released in Japan for the PSP in 2010. The second, Trails to Azure, was released in Japan for the PSP in 2011. The duology did not see official English release for over a decade until NIS America took over rights to the series' English localization in 2019. They released Trails from Zero in 2022 and Trails to Azure in 2023 for PlayStation 4, Nintendo Switch, and Windows. Unlike other English language releases in the Trails series, the Crossbell arc lacks English audio and only includes English subtitles with Japanese audio.
=== Positions on trans identity, accusations of transphobia and connections to the far-right === On January 22, 2020, after a collage was posted in the city of Montpellier calling for the inclusion of trans women in the feminist movement with the slogan "sisters not cisTERF" (a pun on "cis", i.e. not trans, and "TERF", meaning "transgender-exclusionary radical feminist"), she commented she felt trans activism had become too important in the collage movement and within feminism on Twitter. She stated in particular that being a woman is a question of biology and that the activism of trans women was insulting and reduced women to a set of patriarchal stereotypes such as makeup and clothes. She denied trans women's womanhood, stating: "Throughout time, men have tried to silence women by silencing their revolts. Today, they do it from the inside by infiltrating our struggles". She refuses trans-inclusive language such as "people with vulvas". Her positions have led to her being considered a "TERF" by intersectional feminists. Following these statements, the Instagram account Collages Féminicides Paris distanced itself from her comments: "Discrimination has always been condemned […]. We're talking about the exclusion of a part of women from the struggle; transphobia is not a debate." She became increasingly marginalized in the collage movement, months after leaving its leadership. She was the subject of numerous insults on social networks, so much so that the collective reacted and specified that it repudiates any "killing rhetoric".
Sources: en.wikipedia.org
Yes, the terms are generally interchangeable. Lyophilization is more common in pharmaceutical and laboratory contexts, while freeze-drying appears widely in food science and general writing. Both describe removal of solvent by sublimation under vacuum after freezing.
Reduced pressure keeps the process below the triple point of water, so ice can sublimate directly to vapor. It also lowers the temperature needed for drying, which helps preserve heat-sensitive materials. Without vacuum, melting or boiling could occur instead of controlled sublimation.
The rate depends on heat transfer to the product and mass transfer of vapor through the dried layer. A cold condenser, adequate vacuum, and suitable shelf temperature all influence speed. Formulation properties such as solid content and collapse temperature also set practical limits.
No. Freeze-drying removes water but does not reliably kill microorganisms. Sterile lyophilized products are typically prepared aseptically before freezing or are sterilized by a validated method. Microbial control depends on the entire manufacturing process.