Everything below concerns sublimation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-01-02. Numbers and descriptions here follow the published literature rather than marketing material.
A typical cycle begins with freezing, sometimes including an annealing step to control ice crystal size. Freezing conditions influence the pore network that later allows vapor escape. During primary drying, shelf temperature and chamber pressure are set so heat enters the product while its temperature stays below the collapse or eutectic point. Secondary drying then raises the shelf temperature to desorb bound water and lower residual moisture. Cycle design depends on formulation, fill volume, container type, and equipment capability.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Physical state | Solid, porous cake or powder | Depends on formulation and container |
| Typical storage temperature | 2–25 °C, protected from moisture | Some materials require colder conditions |
| Solubility class | Usually readily soluble after reconstitution | Not an intrinsic chemical property |
| Common analytical method | Karl Fischer titration | Used for residual moisture |
| Common synonyms | Freeze-drying; lyophilisation | Lyophilisation is a spelling variant |
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.
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.
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.
Certain crystals alter the polarization plane of transmitted light, and when rotated between crossed polarizers, they alternate between bright and dark every 90°. The extinction angle is the angle between a specific crystal axis and the filter's polarization plane when the crystal appears dark (in extinction). For instance, this method can be employed to distinguish between perlatolic acid and imbricaric acid, which both form long, straight crystals in the GE solvent system but exhibit extinction angles of 0° and 45°, respectively, in relation to their long axis.
== History == Operations began in the early 1920s at a market stall in Hackney, London, with Maurice and Alfred Matlow selling jellied sweets. They built a small factory in east London in 1928 and became known as Matlow Brothers, producing jellies and chews. In 1933 the firm merged with a rival factory owner, David Dee, who specialised in fizzy compressed tablet sweets (although the company officially became Swizzels Matlow Ltd only in 1975). In 1940 the Blitz forced their business to relocate northwards to a disused wick factory in New Mills, Derbyshire, where it remains. Parma Violets were introduced in 1946. Love Hearts were introduced in 1954. Drumsticks were introduced in 1957. Hydrogenated fats were phased out in 2004. Artificial flavourings were discontinued in 2009. The company had revenues of £47 million in 2010/11 and employs around 600 people. Swizzels Matlow exports 20 per cent of its production, to more than 20 countries, mostly in Europe. Its biggest sales period is Halloween.
Molecular formaldehyde. A colorless gas with a characteristic sweetish-pungent irritating odor. It is stable at about 150 °C, but polymerizes when condensed to a liquid. 1,3,5-Trioxane, with the formula (CH2O)3. It is a white solid that dissolves without degrading in organic solvents. It is a trimer of molecular formaldehyde. Paraformaldehyde, with the formula HO(CH2O)nH. It is a white solid that is insoluble in most solvents. It slowly releases monomeric formaldehyde at room temperature. Methanediol, with the formula CH2(OH)2. This compound also exists in equilibrium with various oligomers (short polymers), depending on the concentration and temperature. A saturated water solution, of about 40% formaldehyde by volume or 37% by mass, is called "100% formalin". A small amount of stabilizer, such as methanol, is usually added to suppress oxidation and polymerization. A typical commercial-grade formalin may contain 10–12% methanol as well as metallic impurities. "Formaldehyde" was first used as a generic trademark in 1893 following a previous trade name, "formalin".
Soy flour refers to soybeans ground finely enough to pass through a 100-mesh or smaller screen where special care was taken during desolventizing (not toasted) to minimize denaturation of the protein to retain a high protein dispersibility index, for uses such as food extrusion of textured vegetable protein. It is the starting material for soy concentrate and protein isolate production. Soy flour can also be made by roasting the soybean, removing the coat (hull), and grinding it into flour. Soy flour is manufactured with different fat levels. Alternatively, raw soy flour omits the roasting step.
carbonization 1. The conversion of organic compounds, such as those found in biological organisms, into other forms of carbon or carbonic residues by heating or burning, or during fossilization. 2. The process of coating a substance with carbon residues such as charcoal, or of causing a substance to become scorched, blackened, or charred.
Sources: en.wikipedia.org
Sortase refers to a group of prokaryotic peptidases that modify surface proteins by recognizing and cleaving a carboxyl-terminal sorting signal. For most substrates of sortase enzymes, the recognition signal consists of the motif LPXTG (Leu-Pro-any-Thr-Gly), then a highly hydrophobic transmembrane sequence, followed by a cluster of basic residues such as arginine. Cleavage occurs between the Thr and Gly, with transient attachment through the Thr residue to the active site Cys residue, followed by transpeptidation that attaches the protein covalently to cell wall components. Sortases occur in almost all Gram-positive bacteria and the occasional Gram-negative bacterium (e.g. Shewanella putrefaciens) or Archaea (e.g. Methanobacterium thermoautotrophicum), where cell wall LPXTG-mediated decoration has not been reported. Although sortase A, the "housekeeping" sortase, typically acts on many protein targets, other forms of sortases recognize variant forms of the cleavage motif, or catalyze the assembly of pilins into pili.
The opposite property to ionisation energy is the electron affinity, which is the energy released when adding an electron to the atom. A passing electron will be more readily attracted to an atom if it feels the pull of the nucleus more strongly, and especially if there is an available partially filled outer orbital that can accommodate it. Therefore, electron affinity tends to increase down to up and left to right. The exception is the last column, the noble gases, which have a full shell and have no room for another electron. This gives the halogens in the next-to-last column the highest electron affinities. Some atoms, like the noble gases, have no electron affinity: they cannot form stable gas-phase anions. (They can form metastable resonances if the incoming electron arrives with enough kinetic energy, but these inevitably and rapidly autodetach: for example, the lifetime of the most long-lived He− level is about 359 microseconds.) The noble gases, having high ionisation energies and no electron affinity, have little inclination towards gaining or losing electrons and are generally unreactive. Some exceptions to the trends occur: oxygen and fluorine have lower electron affinities than their heavier homologues sulfur and chlorine, because they are small atoms and hence the newly added electron would experience significant repulsion from the already present ones. For the nonmetallic elements, electron affinity likewise somewhat correlates with reactivity, but not perfectly since other factors are involved.
== Stigma == A 2016 report on stigma concluded "there is no country, society or culture where people with mental illness have the same societal value as people without mental illness". It is also important to comprehend that there are different types of stigmas: the most commonly understood is public stigma, which involves the negative or discriminatory attitudes that others may have about mental illness; it often leads to a more structural stigma, which involves policies of government and private organizations that intentionally or unintentionally limit opportunities for people with mental illness (examples include lower budgets for mental illness research or fewer mental health services in comparison to other types health care); finally, it is unavoidable to not talk about self-stigma, which refers to the negative attitudes, including internalized shame, that people with mental illness may have about their own condition. And stigma about mental illnesses seems to be widely endorsed as well as many misconceptions, the more common being: people with mental illness are homicidal maniacs who need to be feared; they have childlike perceptions of the world that should be marveled; or they are responsible for their illness because they have weak character. Indeed, the public seems to disapprove of people with psychiatric disabilities significantly more than people with related conditions such as physical illness. Severe mental illness has been likened to drug addiction, prostitution, and criminality.
Some have raised ethical objections specifically with respect to pharmaceutical patents and the high prices for drugs that they enable their proprietors to charge, which poor people around the world, cannot afford. Critics also question the rationale that exclusive patent rights and the resulting high prices are required for pharmaceutical companies to recoup the large investments needed for research and development. One study concluded that marketing expenditures for new drugs often doubled the amount that was allocated for research and development. Other critics claim that patent settlements would be costly for consumers, the health care system, and state and federal governments because it would result in delaying access to lower cost generic medicines. Novartis fought a protracted battle with the government of India over the patenting of its drug, Gleevec, in India, which ended up in a Supreme Court in a case known as Novartis v. Union of India & Others. The Supreme Court ruled narrowly against Novartis, but opponents of patenting drugs claimed it as a major victory.
Sources: en.wikipedia.org
=== Less common === Central nervous system: drowsiness, confusion, lethargy, anxiety, fear, unease, dependence, mood changes, impairment of mental and physical performance Gastrointestinal system: constipation Genitourinary system: inability to urinate, bladder spasms Respiratory depression: decreased rate and effort of breathing Hearing impairment, permanent hearing loss Dermatological: rash, itching
=== Economics === Initial pricing (AWP) is $58,000 per reversal (800 mg bolus + 960 mg infusion, $3,300 per 100 mg vial) which is higher than reversal agents for other DOAC agents (idarucizumab for use in dabigatran reversal is $4,200 per reversal).
=== Animals cannot resynthesize carbohydrates from fatty acids === The main fuel stored in the bodies of animals is fat. A young adult human's fat stores average between about 15–20 kg (33–44 lb), but varies greatly depending on age, sex, and individual disposition. In contrast, the human body stores only about 400 g (0.9 lb) of glycogen, of which 300 g (0.7 lb) is locked inside the skeletal muscles and is unavailable to the body as a whole. The 100 g (0.2 lb) or so of glycogen stored in the liver is depleted within one day of starvation. Thereafter the glucose that is released into the blood by the liver for general use by the body tissues, has to be synthesized from the glucogenic amino acids and a few other gluconeogenic substrates, which do not include fatty acids. Fatty acids are broken down to acetyl-CoA by means of beta oxidation inside the mitochondria, whereas fatty acids are synthesized from acetyl-CoA outside the mitochondrion, in the cytosol. The two pathways are distinct, not only in where they occur, but also in the reactions that occur, and the substrates that are used. The two pathways are mutually inhibitory, preventing the acetyl-CoA produced by beta-oxidation from entering the synthetic pathway via the acetyl-CoA carboxylase reaction. It can also not be converted to pyruvate as the pyruvate decarboxylation reaction is irreversible. Instead it condenses with oxaloacetate, to enter the citric acid cycle.
Sources: en.wikipedia.org
Freezing only converts liquid to solid. Lyophilization adds vacuum and controlled warming so frozen solvent sublimes, leaving a dry porous solid. The two steps are related but not interchangeable.
Reduced pressure keeps the solvent below its triple point, allowing ice to become vapor without melting. Vacuum also helps remove water vapor from the product chamber. The exact pressure is chosen with the formulation and equipment.
Residual moisture is water that remains in the dried solid after secondary drying. It is often measured by Karl Fischer titration, near-infrared spectroscopy, or thermogravimetry. Acceptable levels depend on the material and its stability profile.
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.