A practical reference on Sublimation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-09-18 and is reviewed periodically as new material appears.
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.
After primary drying, secondary drying removes water that remains bound to the material. This stage raises the shelf temperature while maintaining low pressure, which encourages desorption of unfrozen water. Residual moisture can be reduced to a low percentage, improving stability for many products. The process parameters, including freezing rate, shelf temperature, and chamber pressure, influence the final pore structure and reconstitution behavior. Control of these variables helps prevent collapse or meltback during drying.
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.
| 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. |
The physics of lyophilization couples heat transfer, mass transfer, and phase behavior. Sublimation requires a vapor pressure difference between the ice front and the chamber, and the dried layer adds resistance to vapor flow. Amorphous formulations are characterized by a glass transition temperature of the maximally freeze-concentrated solute, often denoted Tg'. Crystalline bulking agents can provide structure, while amorphous excipients stabilize labile components. Open questions remain about spatial heterogeneity, edge effects, and how laboratory cycles scale to production.
Lyophilization is a drying process in which a solvent, usually water, is removed from a frozen material by sublimation under reduced pressure. The material is first solidified, then placed under vacuum so that ice transitions directly to vapor without a bulk liquid phase. This approach suits heat-sensitive substances that would degrade during conventional evaporation. Primary drying removes unbound ice, while secondary drying reduces water that remains adsorbed to the solid matrix. The result is a porous, lightweight solid that can be reconstituted later.
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.
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.
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.
Numerous beetles in the Nicrophorus genus are obligately necrophagous, for example Nicrophorus americanus and N. vespilloides. Many other beetles are facultative necrophages including checkered beetles, dermestid beetles, diving beetles, scarab beetles, silphine beetles and water scavenger beetles. Types of carrion eaten include wildlife, livestock and poultry carcasses, livestock viscera and human bodies.
=== Other types === RIT 4385 is a newer strain derived from the Jeryl Lynn strain by Maurice Hilleman, Jeryl Lynn's father. Leningrad-3 strain was developed by Smrodintsev and Klyachko in guinea pig kidney cell culture and has been used since 1950 in former Soviet countries. This vaccine is routinely used in Russia. L-Zagreb strain used in Croatia and India was derived from the Leningrad-3 strain by further passaging. Urabe strain was introduced in Japan, and later licensed in Belgium, France and Italy. It has been associated with a higher incidence of meningitis (1/143 000 versus 1/227 000 for J-L), and abandoned in several countries. It was formulated as MMR in the UK. Rubini strain used mainly in Switzerland was attenuated by a higher number of passes through chicken embryos, and later proved to have low potency. It was introduced in 1985.
While teens may dislike certain aspects of Facebook, such as excessive sharing, they continue to use it because participation is important in terms of socializing with peers. Teens typically keep their Facebook accounts private and make their Twitter accounts public, partly because of the number of adults on the former. Speed and reliability are important factors in choice of social networking platform. This need for quick communication is apparent in the popularity of apps like Vine or Snapchat and the prevalent use of emojis. By the early 2020s, TikTok has become one of the most popular social networks among teenagers and young adults, who frequently use it as a news source and a search engine. Young Americans are willing to ignore their own government's concerns over issues of user privacy and national security, as well as a possible nationwide ban. A notable number of people from Generation Z are the subject of their parents' social media posts. As they grow older, they have opinions about pictures or videos of them being posted online. While some parents do ask for their children's permission before posting, at least some of the time, others simply disregard what their children think. A 2010 report by cybersecurity firm AVG stated that an absolute majority of American children under the age of two had a digital footprint and one in three had their information and photographs posted online within weeks after they were born.
=== Other external data === Analysis of clinical trial data may be carried out by laboratories, image processing specialists or other third parties. The clinical data manager liaises with such data providers and agree data formats and transfer schedules. Data may be reconciled against the CRF to ensure consistency.
Sources: en.wikipedia.org
=== Pharmacokinetics === The metabolism and metabolites of SDMA have been studied. It showed more rapid clearance than MDMA in rodents and hence may have a shorter elimination half-life and/or duration.
== Career == LeBlanc began his academic career in 1989 at North Carolina State University, where he became a professor of Toxicology and Environmental Health. He also served as an adjunct professor from 2012 to 2016 in the Department of Biological Sciences at Clemson University in South Carolina.
Furthermore, various formal and legal issues were found in multiple restaurants, such as dirty waste buckets too close to fresh food, parts of operations done under the company ID of the parent company instead of the actual restaurant as registered with food safety authorities, and incomplete paperwork on deliveries. In September 2025, Czech journalist Jan Tuna reported that the practices of artificially extending the shelf life of meat that led to the closure of all KFC outlets in Denmark may also be used by some branches in the Czech Republic. He cited the testimony of a former employee from the Jablonec nad Nisou branch. The State Agricultural and Food Inspection Authority later revealed that similar practices were used by the KFC outlet in Liberec. The inspection subsequently decided to carry out mass inspections of KFC restaurants throughout the country. In November the spokesperson of the State Agricultural and Food Inspection Authority revealed that employees of the KFC outlet in Prague-Dejvice defrosted chicken meat in standing water, which increases microbiological risks.
== Difference between channels and carriers == A carrier is not open simultaneously to both the extracellular and intracellular environments. Either its inner gate is closed, or its outer gate is closed. That is, its inner and outer gates are never open at the same time. In contrast, a channel can be open to both environments at the same time, allowing the molecules to diffuse without interruption. Carriers have binding sites, but pores and channels do not. When a channel is opened, millions of ions can pass through the membrane per second, but only 100 to 1000 molecules typically pass through a carrier molecule in the same time. Each carrier protein is designed to recognize only one substance or one group of very similar substances. Research has correlated defects in specific carrier proteins with specific diseases.
alpha-decay -> strong interaction, beta-decay -> weak interaction, gamma-decay -> electromagnetism. In alpha decay, a particle containing two protons and two neutrons, equivalent to a He nucleus, breaks out of the parent nucleus. The process represents a competition between the electromagnetic repulsion between the protons in the nucleus and attractive nuclear force, a residual of the strong interaction. The alpha particle is an especially strongly bound nucleus, helping it win the competition more often. However some nuclei break up or fission into larger particles and artificial nuclei decay with the emission of single protons, double protons, and other combinations. Beta decay transforms a neutron into proton or vice versa. When a neutron inside a parent nuclide decays to a proton, an electron, an anti-neutrino, and nuclide with higher atomic number results. When a proton in a parent nuclide transforms to a neutron, a positron, a neutrino, and nuclide with a lower atomic number results. These changes are a direct manifestation of the weak interaction. Gamma decay resembles other kinds of electromagnetic emission: it corresponds to transitions between an excited quantum state and lower energy state. Any of the particle decay mechanisms often leave the daughter in an excited state, which then decays via gamma emission. Other forms of decay include neutron emission, electron capture, internal conversion, cluster decay.
Sources: en.wikipedia.org
Due to its risks, the use of flutamide in cisgender and transgender women is now limited and discouraged. Flutamide and nilutamide have largely been superseded by bicalutamide in clinical practice, with bicalutamide accounting for almost 90% of nonsteroidal antiandrogen prescriptions in the United States by the mid-2000s. Bicalutamide is said to have excellent tolerability and safety relative to flutamide and nilutamide, as well as in comparison to cyproterone acetate. It has few to no side effects in women. Despite its greatly improved tolerability and safety profile however, bicalutamide does still have a small risk of elevated liver enzymes and association with rare cases of serious liver damage and lung disease. Nonsteroidal antiandrogens like bicalutamide may be a particularly favorable option for transgender women who wish to preserve sex drive, sexual function, and/or fertility, relative to antiandrogens that suppress testosterone levels and can greatly disrupt these functions such as cyproterone acetate and GnRH modulators. However, estrogens suppress testosterone levels and at high doses can markedly disrupt sex drive and function and fertility on their own. Moreover, disruption of gonadal function and fertility by estrogens may be permanent after extended exposure.
=== H. G. Wells === Author H. G. Wells was born in Bromley on 21 September 1866, to Sarah and Joseph Wells; his father was the founder of the Bromley Cricket Club and the proprietor of a shop that sold cricket equipment. Wells spent the first 13 years of his life in Bromley. From 1874 to 1879 he attended Tomas Morley's Bromley Academy, at 74 High Street. There was a 'H. G. Wells Centre' in Masons Hill near the southern end of the High Street which housed the Bromley Labour Club (the building was demolished in 2017). In August 2005, the wall honouring Wells in Market Square was repainted; the current wall painting features a rich green background with the same Wells reference and the evolutionary sequence of Homo sapiens featured in Origin of Species by Charles Darwin, a former resident of nearby Downe Village. Wells wrote about Bromley in an early unsigned article in the Pall Mall Gazette in which he expressed satisfaction that he had been born in an earlier, more rural Bromley. A blue plaque marks Wells' birthplace in Market Square, on the wall of what is now a Primark store. A marble plaque appears above the door of 8 South Street, the location of Mrs Knott's Dame school where "Bertie", as he was called as a child, learned to read and write. H. G. Wells featured Bromley in two of his novels: The War in the Air (which refers to Bromley as Bunhill) and The New Machiavelli (in which Bromley is referred to as Bromstead). However, H. G.
== Uses == Along with pharmaceutical applications, it can find utility as food additives, antioxidant, colorant and many other sectors of food industries. Potential pharmaceutical uses of prodigiosin, or its use as a dyestuff, have led to studies of its production from Serratia marcescens, possibly after genetic modification.
In his 1961 return to Kranichstein, Adorno called for what he termed "musique informelle," which would possess the ability "really and truly to be what it is, without the ideological pretense of being something else." Or rather, to admit frankly the fact of non-identity and to follow through its logic to the end."
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 removes water by sublimation from a frozen material, while evaporation changes liquid water into vapor. The low-pressure freezing step avoids the liquid phase and can preserve heat-sensitive structures.