collapse temperature raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-03-21. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonym | Freeze-drying | Same dehydration operation |
| Typical vacuum | 10-100 Pa | Pressure during primary drying |
| Primary drying temperature | -40 to -10 °C | Below collapse temperature for many formulations |
| Cycle duration | 12-72 hours | Varies with load, container, and formulation |
| Key phase change | Sublimation | Solid ice to water vapor |
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.
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.
== Epidemiology == Until the 1990s, little was known regarding the frequency of OSA. A recent meta-analysis of 24 epidemiological studies on the prevalence of OSA in the general population aged 18 and older revealed that for ≥ 5 apnea events per hour, OSA prevalence ranged from 9% to 38%, specifically ranging from 13% to 33% in men and 6% to 19% in women, while in the population aged 65 and older, OSA prevalence was as high as 84%, including 90% in men and 78% in women. Nevertheless, for ≥ 15 apnea events per hour, OSA prevalence ranged from 6% to 17%, and almost 49% prevalence in the older population aged 65 and older. Moreover, a higher BMI is also linked to a higher prevalence of OSA, where a 10% increase in body weight led to a 6-fold risk of OSA in obese men and women. However, OSA is underdiagnosed as it is not always accompanied by daytime sleepiness which can leave the sleep-disordered breathing unnoticed. The prevalence of OSA with daytime sleepiness is thus estimated to affect 3% to 7% of men and 2% to 5% of women, and the disease is common in both developed and developing countries. OSA prevalence increases with age and is most commonly diagnosed in individuals over 65 years old, with estimations ranging from 22.1% to 83.6%. The prevalence has drastically increased in recent decades due to the incidence of obesity. Men are more affected by OSA than women, but the phenomenology differs between the genders. Snoring and witnessed apnea are more frequent among men but insomnia for example is more frequent among women.
== Modern experimental pathology == As new research techniques, such as electron microscopy, immunohistochemistry, and molecular biology have expanded the means by which biomedical scientists can study disease, the definition and boundaries of investigative pathology have become less distinct. In the broadest sense, nearly all research which links manifestations of disease to identifiable processes in cells, tissues, or organs can be considered experimental pathology.
The company's first customers were educational institutions and life-sciences companies that were building supercomputers for purposes of drug discovery, computational fluid dynamics, genetic and genomic research, to predict response to drugs, and for COVID-19 research. Early customers included GlaxoSmithKline, AstraZeneca, the National Energy Technology Laboratory, Lawrence Livermore National Laboratory, the Pittsburgh Supercomputing Center, and Edinburgh Parallel Computing Centre. In September 2020, the company opened an office in Japan and partnered with Tokyo Electron. In April 2021, the company released its CS-2 system, based on the company's Wafer Scale Engine Two (WSE-2), which has 850,000 cores. The CS-2 is manufactured by the 7 nm process of TSMC. It is 26 inches (660 mm) tall and fits in one-third of a standard data center rack. The WSE-2 has 850,000 cores and 2.6 trillion transistors. It enables a single system to support AI models with more than 120 trillion parameters. The WSE-2 expanded on-chip SRAM to 40 gigabytes, memory bandwidth to 20 petabytes per second, and total fabric bandwidth to 220 petabits per second. Customers included TotalEnergies, nference, the National Center for Supercomputing Applications (NCSA), and the Leibniz Supercomputing Centre. In August 2021, Cerebras announced a partnership with Peptilogics on the development of AI for peptide therapeutics. In June 2022, Cerebras set a record for the largest AI models ever trained on one device—a single CS-2 system with one Cerebras wafer trained models with up to 20 billion parameters.
=== Notable cases === As of April 2016, six hyperthymesia cases have been confirmed in peer-reviewed articles, the first being that of Jill Price (initially anonymised as "AJ") in 2006. More cases had been identified by 2012, but are yet to be published. Price's case was originally reported by researchers from the University of California, Irvine, Elizabeth Parker, Larry Cahill and James McGaugh, and is credited as being the first documented case of hyperthymesia. Price can apparently recall every day of her life from when she was 14 years old: "Starting on February 5, 1980, I remember everything. That was a Tuesday." In March 2009, Price was interviewed for an article in Wired magazine by Gary Marcus, a cognitive psychologist at New York University. Price's brain had been subject to a brain scan and the hippocampus and prefrontal cortex had been reportedly normal. Marcus claimed, however, that her brain resembled "those of people with obsessive-compulsive disorder" and suggested that her remarkable memory might be "the byproduct of obsession", claiming also that "the memory woman clings tightly to her past". Price strongly disputed this and McGaugh has also challenged the explanation. Price gave her first interview in over a year for the UK's Channel 4 documentary The Boy Who Can't Forget, and spoke of the challenges of living with the condition. K.
Sources: en.wikipedia.org
It has been suggested that snakes evolved the mechanisms necessary for venom formation and delivery sometime during the Miocene epoch. During the mid-Tertiary, most snakes were large ambush predators belonging to the superfamily Henophidia, which use constriction to kill their prey. As open grasslands replaced forested areas in parts of the world, some snake families evolved to become smaller and thus more agile. However, subduing and killing prey became more difficult for the smaller snakes, leading to the evolution of snake venom. The most likely hypothesis holds that venom glands evolved from specialized salivary glands. The venom itself evolved through the process of natural selection; it retained and emphasized the qualities that made it useful in killing or subduing prey. Today we can find various snake species in stages of this hypothesized development. There are the highly efficient envenoming machines - like the rattlesnakes - with large capacity venom storage, hollow fangs that swing into position immediately before the snake bites, and spare fangs ready to replace those damaged or lost. Other research on Toxicofera, a hypothetical clade thought to be ancestral to most living reptiles, suggests an earlier time frame for the evolution of snake venom, possibly to the order of tens of millions of years, during the Late Cretaceous. Snake venom is produced in modified parotid glands normally responsible for secreting saliva. It is stored in structures called alveoli behind the animal's eyes and ejected voluntarily through its hollow tubular fangs.
On 15 May 2025, during his presidential visit to Qatar, Trump reiterated his desire for the United States to take over the Gaza Strip and "make it a freedom zone". According to "three sources familiar with the effort", Israel and the United States were interested in resettling Gazans to either Syria, Sudan, Morocco, or the separatist Somali regions of Puntland and Somaliland. Somalia and Sudan rejected the proposal, while Puntland and Somaliland expressed willingness to enter discussions on the matter in exchange for diplomatic recognition. In May 2025, reports emerged that the Trump administration was working on a plan to permanently relocate 1 million Gazans to Libya, while offering the release of around $30 billion in funds frozen by the US since the toppling of the regime of Muammar Gaddafi in exchange for Libyan authorities agreeing to the deal. In July, Netanyahu met with Trump and reiterated support for the plan of relocating Palestinians, saying it was "free choice" if Palestinians wanted to stay or leave. The US and Israel were working to identify countries for this plan.
Examples of iron-containing proteins in higher organisms include hemoglobin, cytochrome (see high-valent iron), and catalase. The average adult human contains about 0.005% body weight of iron, or about four grams, of which three quarters is in hemoglobin—a level that remains constant despite only about one milligram of iron being absorbed each day, because the human body recycles its hemoglobin for the iron content. Microbial growth may be assisted by oxidation of iron(II) or by reduction of iron(III).
== Molecular mechanisms == Muscle fatigue may be due to precise molecular changes that occur in vivo with sustained exercise. It has been found that the ryanodine receptor present in skeletal muscle undergoes a conformational change during exercise, resulting in "leaky" channels that are deficient in calcium release. These "leaky" channels may be a contributor to muscle fatigue and decreased exercise capacity.
== Challenges and future outlook == The commercial viability of Pakistan’s oil potential remains uncertain, constrained by geopolitical volatility, investor hesitation, and logistical hurdles. Governance remains a concern—including equitable integration of provincial stakeholders and transparency in licensing. There is anticipation for the first shipment of U.S. crude oil to Pakistan, likely in October 2025 via Cnergyico and Vitol, symbolizing the deal's early implementation. The potential of exports to India remains speculative, heavily contingent on regional diplomacy and stability.
Sources: en.wikipedia.org
It can be argued that in the play Euripides portrays Medea as an enraged woman who kills her children to get revenge on her husband Jason because of his betrayal of their marriage. Medea is often cited as an example of the "madwoman in the attic" trope, in which women who defy societal norms are portrayed as mentally unstable. A competing interpretation is that Medea kills her children because she cares for them and worries about their well-being; once she commits to her plan to kill Creon and Jason's new bride, she knows her children are in danger of being murdered. This is not a paranoid fantasy; at this time in myth and history, helping one's friends and hurting one's enemies was considered a virtue. Thus, by their code of ethics, the Corinthians would do right to avenge their king and princess. (In another version of the myth, the people of Corinth kill her children to avenge the deaths of Creon and his daughter Glauce.) Conversely, a focus on Medea's rage leads to the interpretation that "Medea becomes the personification of vengeance, with her humanity 'mortified' and 'sloughed off'" (Cowherd, 129). Medea's heritage places her in a position more typically reserved for males. Hers is the power of the sun, appropriately symbolized by her great radiance, tremendous heat and boundless passion. In this view Medea is inhuman and her suffering is self-inflicted, just as Jason argues in his debate with her. And yet, if we see events through Medea's eyes, we view a wife intent on vengeance, and a mother concerned about her children's safety and quality of life.
==== January 2024 ==== On 2 January, Israel conducted an airstrike in the Dahieh neighborhood of Beirut, resulting in the assassination of Saleh al-Arouri, the deputy chairman of the Hamas political bureau, and the death of six other members. Al-Arouri was also responsible for the expansion of Hamas's activities in the Israeli-occupied West Bank, including attacks on Israelis. The assassination occurred one day before Hezbollah commemorated the fourth anniversary of the assassination of senior Iranian military commander Qasem Soleimani. On 6 January, Hezbollah launched approximately 40 rockets into northern Israel, describing it as an "initial response" to al-Arouri's killing. According to Israel, the rockets targeted a Air traffic Control Base near Mount Meron, causing significant damage to it. On 8 January, Israel assassinated Wissam al-Tawil, the deputy commander of Hezbollah's Redwan Force, whom it accused of carrying out the attack on Meron airbase two days earlier. In response to al-Tawil's killing, Hezbollah launched a drone attack on Israel's Northern Command headquarters in Safed on the following day, situated approximately 20 kilometres (12 mi) from the border. Ali Hussein Barji, the commander of Hezbollah's aerial forces in southern Lebanon who was reportedly responsible for the attack, was killed by an airstrike, according to Israel, alongside three other Hezbollah members, in Khirbet Selm shortly before al-Tawil's funeral began. However, Hezbollah denied that Barji was killed.
From 1946 through 1993, thirteen countries used ocean disposal or ocean dumping as a method to dispose of nuclear/radioactive waste with an approximation of 200,000 tons sourcing mainly from the medical, research and nuclear industry. Ocean floor disposal of radioactive waste has been suggested by the finding that deep waters in the North Atlantic Ocean do not present an exchange with shallow waters for about 140 years based on oxygen content data recorded over a period of 25 years. They include burial beneath a stable abyssal plain, burial in a subduction zone that would slowly carry the waste downward into the Earth's mantle, and burial beneath a remote natural or human-made island. While these approaches all have merit and would facilitate an international solution to the problem of disposal of radioactive waste, they would require an amendment of the Law of the Sea. Nuclear submarines have been lost and these vessels reactors must also be counted in the amount of radioactive waste deposited at sea. Article 1 (Definitions), 7., of the 1996 Protocol to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, (the London Dumping Convention) states:
In the second half of 1945, Thomas began reading for the BBC Radio programme, Book of Verse, broadcast weekly to the Far East. This provided Thomas with a regular income and brought him into contact with Louis MacNeice, a congenial drinking companion whose advice Thomas cherished. On 29 September 1946, the BBC began transmitting the Third Programme, a high-culture network which provided opportunities for Thomas. He appeared in the play Comus for the Third Programme, the day after the network launched, and his rich, sonorous voice led to character parts, including the lead in Aeschylus's Agamemnon and Satan in an adaptation of Paradise Lost. Thomas remained a popular guest on radio talk shows for the BBC, who regarded him as "useful should a younger generation poet be needed". He had an uneasy relationship with BBC management and a staff job was never an option, with drinking cited as the problem. Despite this, Thomas became a familiar radio voice and within Britain was "in every sense a celebrity". The publication of Deaths and Entrances in February 1946 was a major turning point for Thomas. Poet and critic Walter J. Turner commented in The Spectator, "This book alone, in my opinion, ranks him as a major poet".
=== Evermont: The Royal Rumble === First aired: 2 December 2010 Meet Evermont, a wannabe rapper who says he can "smell the bitch" in his victims. He calls himself "the king" and makes life miserable for Jesse and Colton. Mayhem Miller brings in professional MMA Brazilian jiu-jitsu fighter Bobby "King" Green who has a record of 14 wins and 3 losses to put Evermont in his place. In the first round, Bobby Green made him tap out five times. In the second round, Evermont got scared and didn't continue into the second round. He was the second bully to withdraw from the second round, the first being Emil. Jesse and Colton won $10,000.
Sources: en.wikipedia.org
Primary drying removes ice by sublimation under vacuum. Secondary drying removes water that is bound to the material, often by warming the product after most ice has left. Both stages occur below temperatures that would cause unwanted melting.
Sublimation requires the solvent to remain solid so vapor leaves without passing through a liquid phase. If the product melts, the porous structure can collapse and drying becomes uneven. Maintaining frozen conditions preserves the intended physical form.
No, freeze-drying is a dehydration method, not a sterilization step. It can reduce water activity and limit microbial growth during storage, but it does not reliably kill microbes or remove endotoxins. Sterility must come from separate validated processes.
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.