Collapse temperature comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-08-25. 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.
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.
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.
| 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.
Work by scientists such as Anton Yuryev has contributed to understanding mitochondrial-associated proteins and their interactions. During his postdoctoral research, Yuryev demonstrated that the A-RAF kinase, a signaling protein, can localize to mitochondria, providing insight into how cellular signaling pathways intersect with mitochondrial function. His broader work in molecular biology and bioinformatics has also explored gene regulation, protein interactions, and biological networks, helping to contextualize mitochondrial processes within larger cellular systems.
The word yeast comes from Old English gist, gyst, and from the Indo-European root *yes-, meaning "boil", "foam", or "bubble". Yeast microbes are probably one of the earliest domesticated organisms. Archaeologists digging in Egyptian ruins found early grinding stones and baking chambers for yeast-raised bread, as well as drawings of 4,000-year-old bakeries and breweries. Vessels studied from several archaeological sites in Israel (dating to around 5,000, 3,000 and 2,500 years ago), which were believed to have contained alcoholic beverages (beer and mead), were found to contain yeast colonies that had survived over the millennia, providing the first direct biological evidence of yeast use in early cultures. In 1680, Dutch naturalist Anton van Leeuwenhoek first microscopically observed yeast, but at the time did not consider them to be living organisms, but rather globular structures as researchers were doubtful whether yeasts were algae or fungi. Theodor Schwann recognized them as fungi in 1837.
Sisters went on to achieve critical recognition, being considered among the best American films of the decade by critic Robin Wood, as well as one of the most important films in Kidder's career by film critic G. Allen Johnson. In 1974, she starred in the slasher film Black Christmas, for which she won a Canadian Film Award for Best Actress, followed by a role as a prostitute in the Terrence Malick–scripted The Gravy Train (1974). She received another Canadian Film Award for Best Actress for her performance in the war drama A Quiet Day in Belfast (1974). Also in 1974, Kidder made her directorial debut with a 50-minute short film produced for the American Film Institute, titled Again. The film follows a woman who pastes photographs of her former lovers on her wall, continuously searching for "Mr. Right".
Forty-six Israeli civilians, 28 soldiers and one security officer were killed in Hezbollah's attacks on Israel. An additional three soldiers were killed in non-combat incidents; one by malfunctioning ammunition and the other two in a tank accident. Forty-seven soldiers, including a civilian researcher posthumously recognized as a soldier, were killed during combat in southern Lebanon. Hezbollah's attacks resulted in the evacuation of over 90,000 people—60,000 forced and 30,000 voluntary—from northern Israel. As of July 2024, the Israeli government issued orders for the evacuation of 43 settlements located within 3 miles (4.8 km) of the border with Lebanon. At least eight Israeli UAVs were shot down over Lebanon: four Hermes 450 and four Hermes 900 models. According to the Israeli Army Radio, 2,874 buildings have been reported damaged by Hezbollah, including 841 in need of rebuilding. Property damage was estimated to be around ₪1 billion (US$273 million). As of November 2024, over 60% of the buildings in Metula were destroyed by Hezbollah attacks since the start of the conflict. Three-fourths of the buildings in Manara, 382 buildings in Kiryat Shmona, and 55,000 acres of nature in northern Israel and the Golan Heights have been damaged or destroyed by Hezbollah's attacks, while major damage also took place in Nahariya and Shlomi.
This method has been described as the most viable means of disposing of radioactive waste, and as the state-of-the-art as of 2001 in nuclear waste disposal technology. Another approach termed Remix & Return would blend high-level waste with uranium mine and mill tailings down to the level of the original radioactivity of the uranium ore, then replace it in inactive uranium mines. This approach has the merits of providing jobs for miners who would double as disposal staff, and of facilitating a cradle-to-grave cycle for radioactive materials, but would be inappropriate for spent reactor fuel in the absence of reprocessing, due to the presence of highly toxic radioactive elements such as plutonium within it. Deep borehole disposal is the concept of disposing of high-level radioactive waste from nuclear reactors in extremely deep boreholes. Deep borehole disposal seeks to place the waste as much as 5 kilometres (3.1 mi) beneath the surface of the Earth and relies primarily on the immense natural geological barrier to confine the waste safely and permanently so that it should never pose a threat to the environment. The Earth's crust contains 120 trillion tons of thorium and 40 trillion tons of uranium (primarily at relatively trace concentrations of parts per million each adding up over the crust's 3 × 1019 ton mass), among other natural radioisotopes.
Sources: en.wikipedia.org
== History == The safety and effectiveness of donislecel was evaluated in two non-randomized, single-arm studies in which a total of 30 participants with type 1 diabetes and hypoglycemic unawareness received at least one infusion and a maximum of three infusions. Overall, 21 participants did not need to take insulin for a year or more, with eleven participants not needing insulin for one to five years and ten participants not needing insulin for more than five years. Five participants did not achieve any days of insulin independence. The FDA granted marketing approval of Lantidra to CellTrans, Inc.
Nicotine was originally isolated from the tobacco plant in 1828 by chemists Wilhelm Heinrich Posselt and Karl Ludwig Reimann from Germany, who believed it was a poison. Its chemical empirical formula was described by Melsens in 1843, its structure was discovered by Adolf Pinner and Richard Wolffenstein in 1893, and it was first synthesized by Amé Pictet and A. Rotschy in 1904. Nicotine is named after the tobacco plant Nicotiana tabacum, which in turn is named after the French ambassador in Portugal, Jean Nicot de Villemain, who sent tobacco and seeds to Paris in 1560, presented to the French King, and who promoted their medicinal use. Smoking was believed to protect against illness, particularly the plague. However, the "holy herb", tobacco, had first reached Europe by the early 1530s, brought by Spanish explorers. Following its introduction, tobacco rapidly gained popularity in Europe for its stimulating effects, fueled by nicotine's addictive and pharmacological properties and tobacco's widespread embrace as a cure-all. By the early 17th century, this allure fueled its mercilessly laborious cultivation as a cash crop in the Virginia colonies, where John Rolfe's introduction in 1612 rescued Jamestown from economic collapse and famine, transforming it into a prosperous export hub with over 20,000 pounds shipped by 1619 and laying the groundwork for transatlantic trade.
== Financial information == From the founding of the company in 1976 to 1988, the revenue of KCI grew to US$153.2 million. The growth in revenue allowed KCI to go public and trade on the New York Stock Exchange (NYSE) in 1988. KCI stock was traded on the NYSE until 1997, when the company went private. In February 2004, KCI became a publicly listed company for the second time and was listed on the NYSE under the ticker symbol KCI. By the late 2000s, the company's revenue was over $1 billion and reported an increase of 17 percent in 2007 to $1.61 billion. Revenue for 2008 was $1.88 billion, increasing to $1.99 billion in 2009 and in 2010 increased to $2.02 billion. On November 4, 2011, the company went private again at a price of $68.50 per share.
== Tissue development == Haptotaxis plays a role in organizing cells to form tissues and specific regions of those tissues. Fibronectin and laminin both play a role in adrenocyte mutation into distinctive distribution in the adrenal gland. The adrenocytes migrate centripetally as they mature towards the medulla of the adrenal gland, and this movement may be a result of haptotactic forces mediated by fibronectin and laminin. In nerve cells, axonal growth is mediated by nerve growth factor in a haptotactic manner, where the axon of nerve cells grows along the gradient. This information could be used to possibly develop methods to promote nerve regeneration in patients that have nerve damage. Another regenerative strategy is the use of mesenchymal stem cells, which can differentiate into different kinds of connective tissue in the wound healing process. The haptotaxis is mediated by fibronectin, vitronectin, and type I collagen. A recent study has tentatively proposed the idea that the structures on cells responsible for sensing the membrane protein gradients are attenuated filopodia. Also, the more amount of filopodia present on the leading edge of the migrating cell, the more responsive the cell is to the haptotactic gradient. This is important because there is the possibility that all motile cells that display filopodia may be responding to haptotactic gradients. Further research is required in the subject, but it is clear that more and more kinds of cell undergo haptotaxis than originally believed.
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.