This is a working overview of Collapse temperature, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
The process relies on the phase diagram of water, where the triple point marks the conditions at which ice, liquid water, and vapor coexist. By maintaining pressure below this point, typically around 0.01 to 0.1 millibar, sublimation becomes the dominant mechanism. Formulations often include excipients such as sugars or polymers that act as lyoprotectants and bulking agents. These additives help preserve the structure of the active ingredient and prevent collapse during drying. The choice of excipient and freezing rate influences the final cake morphology and stability.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
| 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. |
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.
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.
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.
On January 6, 2021, following the U.S. Capitol attack, Bush denounced the violence and attack alongside the three other living former presidents, Obama, Clinton, and Carter, releasing a statement saying that "this is how election results are disputed in a banana republic, not our democratic republic", and that "it is a sickening and heartbreaking sight". He also echoed president-elect Biden's message saying that what occurred at the Capitol was an "insurrection". On January 20, Bush and his wife attended Biden's inauguration. Bush opposed President Biden's withdrawal of American troops from Afghanistan, saying that the withdrawal made him "concerned" and that it had the potential to "create a vacuum, and into that vacuum is likely to come people who treat women as second-class citizens". During an interview with Deutsche Welle on July 14, 2021, Bush reaffirmed his opposition to the troop withdrawal, calling the plan "a mistake". On September 11, 2021, the 20th anniversary of the September 11 attacks, Bush gave a speech at the Flight 93 National Memorial, praising the heroism of the people on Flight 93 and the spirit of America. He also said that he "saw millions of people instinctively grab for a neighbor's hand and rally to the cause of one another. That is the America I know." Bush condemned the assassination attempt on then-former president Trump, who was the presumptive Republican nominee, on July 13, 2024, calling it "cowardly" and applauding the Secret Service's response.
=== Opposition === Opponents of lethal injection have voiced concerns that abuse, misuse and even criminal conduct are possible when there is not a proper chain of command and authority for the acquisition of death-inducing drugs.
In February 2005, Bagwell and Biggio were jointly inducted into the Texas Sports Hall of Fame. Shortly after the 2005 season began, the chronic arthritic condition in his shoulder that had begun in 2001 finally sidelined him, rendering him inactive for three-quarters of the season. The former Gold Glove winner was now a defensive liability with a severely limited throwing arm; he had to "push" the ball instead of throwing it. Teams began taking advantage of his defensive weakness. Once possessing great ability to throw out the lead runner at third base ahead on bunt plays, Bagwell found it difficult to practice with the other infielders between innings. Concurrently, Bagwell's offensive production suffered, and pressure mounted on Astros management to bench the perennial All-Star; the club had started the season with a 15–30 won–loss record. He hit his last major league home run against Maddux on April 29, tying him for the most against any pitcher with seven. Bagwell continued to play through the pain until, after going 0-for-5 in a loss to the Pirates on May 4, it became so unbearable that he asked manager Phil Garner to remove him from the lineup the following day. He had hit just .250 with three home runs in 88 at-bats. The Astros placed him on the disabled list a few days later, and shoulder surgery followed. The Astros dramatically improved after their poor start to finish 74–43 over their final 117 games and capture the NL wild card.
Ketobemidone, sold under the brand name Ketogan (a mixture of ketobemidone and Spasmolytic A29) among others, is a powerful synthetic opioid painkiller. Its effectiveness against pain is in the same range as morphine, and it also has some NMDA-antagonist properties imparted, in part, by its metabolite norketobemidone. This may make it useful for some types of pain that do not respond well to other opioids. It is marketed in Denmark, Iceland, Norway. Until 2024 it was available in, but is now withdrawn in Sweden. It is used for severe pain.
Sources: en.wikipedia.org
== History == The phenomenon of prohormone conversion was discovered by Donald F. Steiner while examining the biosynthesis of insulin in 1967. At the same time, while conducting chemical sequencing of β-lipotrophic hormone (βLPH) with sheep pituitary glands Dr. Michel Chrétien determined the sequence of another hormone, melanocyte-stimulating hormone ( βMSH). This was the chemical evidence, at the level of primary protein sequence that peptide hormones could be found within larger protein molecules. The identity of the responsible enzymes was not clear for decades. In 1984, David Julius, working in the laboratory of Jeremy Thorner, identified the product of the Kex2 gene as responsible for processing of the alpha factor mating pheromone. Robert Fuller, working with Thorner, identified the partial sequence of the Kex2-homologous Furin gene in 1989. In 1990 human Kex2-homologous genes were cloned by the Steiner group, Nabil Seidah and co-workers, Wim J.M. van de Ven and co-workers, Yukio Ikehara and co-workers, Randal Kaufman and co-workers, Gary Thomas and co-workers, and Kazuhisa Nakayama and co-workers.
== History == The NAFBL was formed in January 1895 and in March 1895, the NAFBL began operation as the third significant U.S. soccer league. It drew its teams primarily from northern New Jersey and New York City. Few records exist for the league, but the teams and standings for four of the five seasons do exist. After its first spring-summer season in 1895, the NAFBL moved to a winter schedule in the fall of 1895. On December 16, 1895, the NAFBL opened its second season with a game pitting the Kearny Scottish-Americans and the International Athletic Club. In 1899, a deep recession, accompanied by the Spanish–American War led to the collapse of several athletic leagues and teams, among them the NAFBL. On August 14, 1906, the league was revived and continued in operation until 1921. That year, several of the top NAFBL teams, frustrated by the amateur/semi-professional nature of the league, joined with other top North Atlantic U.S. teams to form the first fully professional U.S. soccer league, the American Soccer League.
=== Drug delivery === Researchers at Monash University discovered that a sheet of graphene oxide can be transformed into liquid crystal droplets spontaneously—like a polymer—simply by placing the material in a solution and manipulating the pH. The graphene droplets change their structure in the presence of an external magnetic field. This finding raises the possibility of carrying a drug in graphene droplets and releasing the drug upon reaching the targeted tissue by making the droplets change shape in a magnetic field. Another possible application is in disease detection if graphene is found to change shape at the presence of certain disease markers such as toxins. A graphene 'flying carpet' was demonstrated to deliver two anti-cancer drugs sequentially to the lung tumor cells (A549 cell) in a mouse model. Doxorubicin (DOX) is embedded onto the graphene sheet, while the molecules of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) are linked to the nanostructure via short peptide chains. Injected intravenously, the graphene strips with the drug payload preferentially concentrate to the cancer cells due to common blood vessel leakage around the tumor. Receptors on the cancer cell membrane bind TRAIL and cell surface enzymes clip the peptide thus release the drug onto the cell surface. Without the bulky TRAIL, the graphene strips with the embedded DOX are swallowed into the cells. The intracellular acidic environment promotes DOX's release from graphene. TRAIL on the cell surface triggers the apoptosis while DOX attacks the nucleus.
The affinity, given as the dissociation constant (Kd), between a TCR and a pMHC was determined by surface plasmon resonance (SPR) to be in the range of 1–100 μM, with an association rate (kon) of 1000 -10000 M−1 s−1 and a dissociation rate (koff) of 0.01 -0.1 s−1. In comparison, cytokines have an affinity of KD = 10–600 pM to their receptor. It has been shown that even a single amino acid change in the presented peptide that affects the affinity of the pMHC to the TCR reduces the T-cell response and cannot be compensated by a higher pMHC concentration. A negative correlation between the dissociation rate of the pMHC-TCR complex and the strength of the T-cell response has been observed. That means, pMHC that bind the TCR for a longer time initiate a stronger activation of the T cell. Furthermore, T cells are highly sensitive; interaction with a single pMHC is enough to trigger activation. T cells move on quickly from antigens that do not trigger responses, rapidly scanning pMHC on an antigen-presenting cell (APC) to increase the chance of finding a specific pMHC. On average, a T cell encounters 20 APCs per hour. Different models for the molecular mechanisms that underlie this highly specific and highly sensitive process of antigen discrimination have been proposed. The occupational model simply suggests that the TCR response is proportional to the number of pMHC bound to the receptor. Given this model, a shorter lifetime of a peptide can be compensated by higher concentration such that the maximum response of the T cell stays the same.
The letter stated, "Our organizations deplore the use of chlorine in this manner. The indiscriminate attacks, possibly carried out by a member state of the Chemical Weapons Convention (CWC), are of concern to chemical scientists and engineers around the globe and we stand ready to support your mission of implementing the CWC." According to the CWC, "the use, stockpiling, distribution, development or storage of any chemical weapons is forbidden by any of the 192 state party signatories."
Sources: en.wikipedia.org
Nearer Secret of Life." The news reached readers of The New York Times the next day; Victor K. McElheny, in researching his biography, "Watson and DNA: Making a Scientific Revolution", found a clipping of a six-paragraph New York Times article written from London and dated 16 May 1953 with the headline "Form of 'Life Unit' in Cell Is Scanned". The article ran in an early edition and was then pulled to make space for news deemed more important. (The New York Times subsequently ran a longer article on 12 June 1953). The university's undergraduate newspaper Varsity also ran its own short article on the discovery on Saturday 30 May 1953. Bragg's original announcement of the discovery at a Solvay conference on proteins in Belgium on 8 April 1953 went unreported by the British press. In a seven-page, handwritten letter to his son at a British boarding school on 19 March 1953 Crick explained his discovery, beginning the letter "My Dear Michael, Jim Watson and I have probably made a most important discovery". The letter was put up for auction at Christie's New York on 10 April 2013 with an estimate of $1 to $2 million, eventually selling for $6,059,750, the largest amount ever paid for a letter at auction. Sydney Brenner, Jack Dunitz, Dorothy Hodgkin, Leslie Orgel, and Beryl M Oughton, were some of the first people in April 1953 to see the model of the structure of DNA, constructed by Crick and Watson; at the time they were working at Oxford University's Chemistry Department.
== Reception == Lost Coast was generally well received by video game critics. 1UP.com enjoyed the amount of detail, including the graphics, puzzles, and intelligent enemies, saying, "Valve just packed more atmosphere into a tiny snippet than most shooters muster, period." The review also praised the level's commentary system, calling it an informative addition, and enjoyed the interesting and insightful comments made by some of its creators. The level satisfied UGO because "it would be harder not to enjoy this level in all its beautifully rendered glory—even after you've broken all the windows and spattered the walls with Combine blood," and GameSpot commented that "the textures in Lost Coast are noticeably more detailed and numerous than in the retail game." The review concluded hoping that the features introduced in Lost Coast would be included in Valve's future releases. Negative reaction to the game focused on its length and gameplay. 1UP.com and UGO both considered it short; Shawn Elliott of 1UP.com described it as "a lickety-split run through postcard-pretty tide pools, up cliffs, and into a church turned Combine outpost". UGO's Nigel Grammer stated that Lost Coast's gameplay seemed secondary to the graphics. The gameplay also disappointed Brad Shoemaker of GameSpot, who found it too similar to Half-Life 2 and so "isn't going to set the world on fire".
=== Development === In Nicotiana attenuata HypSys is known to not be involved in defence against insect herbivores. Silencing and over-expression of HypSys does not affect the feeding performance of larvae compared to normal plants. Berger silenced HypSys and found that it caused changes in flower morphology which reduced the efficiency of self-pollination. The flowers had pistils that protruded beyond their anthers, a similar phenotype to CORONATINE-INSENSITIVE1-silenced plants which lack a jasmonate receptor. Measurement of jasmonate levels in the flowers revealed that they were lower than in normal plants. The authors suggested that HypSys peptides in N. attenuata have diversified from their function as defence related peptides to being involved in controlling flower morphology. The signalling processes remain similar however, being mediated through jasmonates. Systemin also increases root growth in Solanum pimpinellifolium suggesting that it may also play some role in plant development.
== Ecological relevance == Numerous studies and published data comparing Microtox results with toxicity values for fish, crustaceans and algae have found a positive correlation. However, others have pointed out that the effect of luminosity on the survival of organisms is unknown. Concerns have also been expressed regarding the use of sediment extracts and not the sediment itself. It is possible that only water-soluble contaminants will be tested for, and therefore may not be representative of the full range of contaminants present in the sediment. Extracts may also remove contaminants that are not bioavailable. This could lead to an over or under estimation of contaminants and their biological effects.
== Pathogenicity == The disease is characterized by epididymitis and orchitis in male dogs, endometritis, placentitis, and abortions in females, and often presents as infertility in both sexes. Other symptoms such as inflammation in the eyes and axial and appendicular skeleton; lymphadenopathy and splenomegaly, are less common. Although there has been an increase in the international movement of dogs, Brucella canis is still very uncommon. Signs of this disease are different in both genders of dogs; females that have B. canis infections face an abortion of their developed fetuses. Males face the chance of infertility, because they develop an antibody against their spermatozoa. This may be followed by inflammation of the testes which generally settles down a while after. Another symptom is the infection of the spinal plates or vertebrae, which is called diskospondylitis. It is generally spotted in the animal's reproductive organs. This infection usually causes the animal to spontaneously abort a fetus and can also cause an animal to become sterile.
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.
Conventional drying uses heat to evaporate water from a material, while lyophilization freezes the material and removes water by sublimation under vacuum. This avoids the liquid phase and reduces thermal damage to sensitive substances. The result is a porous cake that reconstitutes quickly.