Everything below concerns glass transition. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
Stability studies examine how temperature, humidity, and time influence a lyophilized product. Accelerated conditions provide early information about degradation pathways, while long-term studies support shelf-life claims. The glass transition temperature of the dried formulation can indicate its physical stability, and storage above this temperature may increase molecular mobility and lead to collapse or aggregation. Container closure integrity also matters because moisture or oxygen ingress can degrade the product, so vial stoppers and seals are part of the quality system.
Handling and storage practices aim to keep the cake intact and dry. Vials are typically stored upright at controlled temperatures, often between 2 °C and 8 °C or at -20 °C for longer-term use. Reconstitution involves adding a suitable diluent and gently mixing until the solid dissolves. Shaking or rapid injection of diluent can create foam or damage sensitive molecules. Once reconstituted, the product may require refrigeration and use within a defined period.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilisation is the British spelling; the process is not simple evaporation. |
| Primary drying pressure | 0.05–0.3 mbar | Pressure must remain below the vapor pressure of ice at the product temperature. |
| Sublimation temperature | Below 0 °C | Ice changes directly to vapor while the product remains frozen. |
| Typical shelf temperature | −40 to −10 °C | Exact setting depends on formulation critical temperature and equipment. |
| Cycle duration | 12–72 hours | Time varies with fill volume, formulation, and dryer performance. |
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.
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.
Analytical methods for lyophilized solids must account for the low moisture content and the fragile cake. Karl Fischer titration is widely used for water content, while near-infrared spectroscopy can measure moisture non-destructively in sealed containers. X-ray diffraction and modulated differential scanning calorimetry help identify crystalline or amorphous phases. Residual solvent analysis may be needed if organic solvents were used during formulation. The combination of these methods supports batch release and long-term stability assessment.
Lyophilized products are typically stored as sealed solids in vials or syringes. Moisture ingress is a major concern because many dried cakes are hygroscopic and can lose stability when exposed to humid air. Storage temperature depends on the formulation; some products are kept refrigerated, while others are stable at room temperature. Container closure integrity and headspace moisture are often monitored. Light protection may also be required for some photosensitive materials.
=== Types === The ABO blood group system was discovered in the year 1900 by Karl Landsteiner. Jan Janský is credited with the first classification of blood into the four types (A, B, AB, and O) in 1907, which remains in use today. In 1907 the first blood transfusion was performed that used the ABO system to predict compatibility. The first non-direct transfusion was performed on 27 March 1914. The Rhesus factor was discovered in 1937.
==== United States market (brands, formats, and recent changes) ==== The leading seller in the e-cigarette market in the US is the Juul e-cigarette, which was introduced in June 2015. As of August 2018, Juul accounts for over 72% of the US e-cigarette market monitored by Nielsen, and its closest competitor—RJ Reynolds' Vuse—makes up less than 10% of the market. Juul rose to popularity quickly, growing by 700% in 2016 alone. On 17 July 2018 Reynolds announced it will debut in August 2018 a pod mod type device similar Juul. The popularity of the Juul pod system has led to a flood of other pod devices hitting the market. Since 2018 the US e-cigarette market has shifted. During January 2020-December 2022, disposable cigarette unit share increased from 24.7% to 51.8%, while prefilled cartridge share decreased from 75.2% to 48.0%. For the four-week period ending December 25, 2022, the top-selling brands were Vuse, JUUL, Elf Bar, NJOY, and Breeze Smoke. In the 52 weeks ended June 15, 2024, Vuse Alto products represented approximately 40% of U.S. e-cigarette sales in stores tracked by NielsenIQ, according to an analyst cited by The Wall Street Journal. In the US the Federal Trade Commission reported that e-cigarette product sales for major reporting manufacturers rose to $2.703 billion in 2019 and then declined to $2.224 billion in 2020, with the FTC noting this may reflect a shift to other market participants. In US retail scanner data, the number of e-cigarette brands increased from 184 in January 2020 to 269 in December 2022.
In situ conservation Ex situ conservation List of colossal sculptures in situ List of Latin phrases Neoclassical compound – Compound words composed from Latin or ancient Greek All pages with titles beginning with In situ
=== DDM === Direct Drive Monitor (DDM) 1.0 standard was approved in December 2008. It allows for controller-less monitors where the display panel is directly driven by the DisplayPort signal, although the available resolutions and color depth are limited to two-lane operation.
Sources: en.wikipedia.org
The first Pan-Slavic convention was held in Prague on June 2 through 16, 1848. The delegates at the Congress were specifically both anti-Austrian and anti-Russian. Still "the Right"—the moderately liberal wing of the Congress—under the leadership of František Palacký (1798–1876), a Czech historian and politician, and Pavol Jozef Šafárik (1795–1861), a Slovak philologist, historian and archaeologist, favored autonomy of the Slav lands within the framework of Austrian (Habsburg) monarchy. In contrast "the Left"—the radical wing of the Congress—under the leadership of Karel Sabina (1813–1877), a Czech writer and journalist, Josef Václav Frič, a Czech nationalist, Karol Libelt (1817–1861), a Polish writer and politician, and others, pressed for a close alliance with the revolutionary-democratic movement going on in Germany and Hungary in 1848. A national rebirth in the Hungarian "Upper Land" (now Slovakia) awoke in a completely new light, both before the Slovak Uprising in 1848 and after. The driving force of this rebirth movement were Slovak writers and politicians who called themselves Štúrovci, the followers of Ľudovít Štúr. As the Slovak nobility was Magyarized and most Slovaks were merely farmers or priests, this movement failed to attract much attention. Nonetheless, the campaign was successful as brotherly cooperation between the Croats and the Slovaks brought its fruit throughout the war. Most of the battles between Slovaks and Hungarians however, did not turn out in favor for the Slovaks who were logistically supported by the Austrians, but not sufficiently.
== Adverse effects == Adverse effects of doxycycline are similar to those of other members of the tetracycline antibiotic group. Doxycycline can cause gastrointestinal upset. Oral doxycycline can cause pill esophagitis, particularly when it is swallowed without adequate fluid, or by persons with difficulty swallowing or reduced gastrointestinal motility. Doxycycline is less likely than other antibiotic drugs to cause Clostridioides difficile colitis. An erythematous (red) rash in sun-exposed parts of the body has been reported to occur in 7.3–21.2% of persons taking doxycycline as prophylaxis against malaria. The rash resolves upon discontinuation of the drug. One study examined the tolerability of various malaria prophylactic regimens and found doxycycline did not cause a significantly higher percentage of skin events (such as rash, itching, or photosensitivity) when compared with other antimalarials. Unlike some other members of the tetracycline group, doxycycline may be used in those with renal impairment, because it is primarily excreted via the feces rather than the kidneys, and does not accumulate to toxic levels when kidney function is reduced. Doxycycline use has been associated with increased risk of inflammatory bowel disease. In one large retrospective study, patients who were prescribed doxycycline for their acne had a 2.25-fold greater risk of developing Crohn's disease.
== Hormone receptor antagonists == Hormone receptor antagonists bind to the normal receptor for a given hormone and prevent its activation. The target receptor may be on the cell surface, as in the case of peptide and glycoprotein hormones, or it may be intracellular, as in the case of steroid hormone receptors.
The magnocellular cells in the PVN elaborate and secrete two peptide hormones: oxytocin and vasopressin. These hormones are packaged into large vesicles, which are then transported down the unmyelinated axons of the cells and released from neurosecretory nerve terminals residing in the posterior pituitary gland. Similar magnocellular neurons are found in the supraoptic nucleus which also secrete vasopressin and oxytocin.
Beak trimming (also spelled as beak-trimming; informally as debeaking), or beak conditioning, is the partial removal of the beak of poultry, especially layer hens and turkeys, although it is also performed on some quail and ducks. When multiple birds are confined in small spaces, they are more likely to hurt each other through pecking. Beak trimming aims to avoid damage done by pecking, although the practice is criticized by animal welfare organizations and banned in several European countries. Beak trimming is most common in egg-laying strains of chickens. In some countries, such as the United States, turkeys routinely have their beaks trimmed. In the UK, only 10% of turkeys are beak trimmed. In close confinement, cannibalism, feather pecking and aggression are common among turkeys, ducks, pheasants, quail, and chickens of many breeds (including both heritage breeds and modern hybrids) kept for eggs. The tendency to cannibalism and feather pecking varies among different strains of chickens, but does not manifest itself consistently. Some flocks of the same breed may be entirely free from cannibalism, while others, under the same management, may have a serious outbreak. Mortalities, mainly due to cannibalism, can be up to 15% in egg laying flocks housed in aviaries, straw yards, and free-range systems. Because egg laying strains of chickens can be kept in smaller group sizes in caged systems, cannibalism is reduced leading to a lowered trend in mortality as compared to non-cage systems.
Sources: en.wikipedia.org
=== Pesticides === Many pesticides are enzyme inhibitors. Acetylcholinesterase (AChE) is an enzyme found in animals, from insects to humans. It is essential to nerve cell function through its mechanism of breaking down the neurotransmitter acetylcholine into its constituents, acetate and choline. This is somewhat unusual among neurotransmitters as most, including serotonin, dopamine, and norepinephrine, are absorbed from the synaptic cleft rather than cleaved. A large number of AChE inhibitors are used in both medicine and agriculture. Reversible competitive inhibitors, such as edrophonium, physostigmine, and neostigmine, are used in the treatment of myasthenia gravis and in anaesthesia to reverse muscle blockade. The carbamate pesticides are also examples of reversible AChE inhibitors. The organophosphate pesticides such as malathion, parathion, and chlorpyrifos irreversibly inhibit acetylcholinesterase.
== Drug interactions == Smoking is known to increase levels of liver enzymes that break down drugs and toxins. That means that drugs cleared by these enzymes are cleared more quickly in smokers, which may result in the drugs not working. Specifically, levels of CYP1A2 and CYP2A6 are induced: substrates for 1A2 include caffeine and tricyclic antidepressants such as amitriptyline; substrates for 2A6 include the anticonvulsant valproic acid.
Prigozhin denied the allegations in a Telegram statement on 15 May, while the Kremlin described the report as a hoax. The Ukrainian air force said it destroyed 25 drones and three cruise missiles in another massive overnight attack by Russia. Seven people were killed and another 16 were injured in Russian shelling in Donetsk and Kherson oblasts. Russian-installed officials said mobile internet was temporarily suspended in occupied areas of Luhansk oblast due to increased shelling by Ukrainian troops.
=== Research === As detailed in the table below, the potential is great for the development of heparin-like structures as drugs to treat a wide range of diseases, in addition to their current use as anticoagulants.
This mechanism of the neonatal FcRn involves albumin binding to the FcRn in an acidic pH environment to divert it from degradation in the lysosomal compartment of the cell, and redirecting it to the plasma membrane, where it is released back into the blood plasma due to neutral pH. Lipidation is a further technique to use when improving peptide stability and half-life. Attaching a lipid chain to the peptide head group has been found to inhibit proteolytic attack due to the lipid chain non-covalently interacting with serum albumin to increase the molecular weight, thus reducing renal filtration. Studies on a lipidated analogue of insulin, detemir, revealed a prolonged action as a result of its affinity for human serum albumin. As well as this, lipidation has been shown to enhance the interaction of peptides with cell membranes, allowing them to be up taken into the cell more readily compared to the peptide lacking the lipid moiety. There are three types of lipidation, and they differ based on the bond formation methods between the lipid and the peptide: amidation, esterification (S- or O-) and S-bond (ether or disulphide) formation. Amidation and O-esterification form strong covalent bonds that are irreversible, whereas the other two methods are weak and reversible covalent bonds. The method used, as well as the alkyl/lipid chain, position of lipidation, and the spacer used, all have significant impacts on physiochemical properties and bioactivity.
Sources: en.wikipedia.org
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.
Freezing determines ice crystal size, solute distribution, and the pore network left after drying. A slow or fast freezing rate can produce different cake structures and affect reconstitution. It also sets whether the formulation follows an amorphous or crystalline drying path.
It removes most free water during primary drying and part of the bound water during secondary drying. A small residual moisture content often remains and is specified for each product. Complete removal is generally neither practical nor desirable for stability.
Residual moisture can influence chemical degradation, cake collapse, and long-term stability. Low moisture levels usually improve stability, but each product has an optimal range.