Everything below concerns Primary drying. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-02-14. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | freeze-drying, lyophilisation, cryodesiccation | Lyophilization is common in pharmaceutical literature. |
| Typical chamber pressure during primary drying | 0.05–0.5 mbar (5–50 Pa) | Must remain below the triple point of water. |
| Typical shelf temperature during freezing | −40 to −20 °C | Lower temperatures may be used for eutectic systems. |
| Typical residual moisture after secondary drying | 0.5–3% w/w | Product-dependent; low moisture improves stability but can cause over-drying. |
| Typical analytical method for residual moisture | Karl Fischer titration or loss on drying | Thermogravimetric methods are also used. |
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.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
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.
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.
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.
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.
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.
Type XVIII collagen is a type of collagen which can be cleaved to form endostatin. The endostatin is from the c terminus end of the collagen XVIII, and is known to have an inhibitory effect on the growth of blood vessels. This is seen with tumors, where endostatin inhibits the growth of the blood vessels of the tumor as well as the overall growth of the tumor. The collagen XVIII is located within the basement membrane, and plays a major role in the integrity of the structure of the basement membrane for both endothelial and epithelial cells. The collagen XVIII has three different isoforms. While each of the isoforms has the same C-terminus end, they have a varying structure on the N-terminus end, which results in the formation of short, medium or long form Collagen XVIII.
=== Scarless wound healing === Scarless wound healing is a concept based on the healing or repair of the skin (or other tissue/organs) after injury with the aim of healing with subjectively and relatively less scar tissue than normally expected. Scarless healing is sometimes mixed up with the concept of scar free healing, which is wound healing that results in absolutely no scar (free of scarring) may occur naturally at some locations of the human body and research in 2025 has decoded molecular players that drive that scarless healing. However, they are different concepts. The opposite of scarless wound healing is scarification (wound healing to scar more). Historically, certain cultures consider scarification attractive; however, this is generally not the case in the modern western society, in which many patients are turning to plastic surgery clinics with unrealistic expectations. Depending on scar type, treatment may be invasive (intralesional steroid injections, surgery) and/or conservative (compression therapy, topical silicone gel, brachytherapy, photodynamic therapy). Clinical judgment is necessary to successfully balance the potential benefits of the various treatments available against the likelihood of a poor response and possible complications resulting from these treatments. Many of these treatments may only have a placebo effect, and the evidence base for the use of many current treatments is poor.
== Interface with other metabolic and salvage pathways == Protein catabolism produces amino acids that are used to form other proteins or oxidized to meet the energy needs of the cell. The amino acids that are produced by protein catabolism can then be further catabolized in amino acid catabolism. Among the several degradative processes for amino acids are Deamination (removal of an amino group), transamination (transfer of amino group), decarboxylation (removal of carboxyl group), and dehydrogenation (removal of hydrogen). Degradation of amino acids can function as part of a salvage pathway, whereby parts of degraded amino acids are used to create new amino acids, or as part of a metabolic pathway whereby the amino acid is broken down to release or recapture chemical energy. For example, the chemical energy that is released by oxidization in a dehydrogenation reaction can be used to reduce NAD+ to NADH, which can then be fed directly into the Krebs/Citric Acid (TCA) Cycle.
An Iranian ballistic missile strike damaged an Israeli drone factory in Petah Tikva. On the same day, Iran's army chief, Amir Hatami, stated that if US forces invade the country, "not a single person" among the invaders will survive.
Sources: en.wikipedia.org
Minerals are generally oxidized derivatives of metals. Iron is mined as ores such as magnetite (Fe3O4) and hematite (Fe2O3). Titanium is mined as its dioxide, usually in the form of rutile (TiO2). These oxides must be reduced to obtain the corresponding metals, often achieved by heating these oxides with carbon or carbon monoxide as reducing agents. Blast furnaces are the reactors where iron oxides and coke (a form of carbon) are combined to produce molten iron. The main chemical reaction producing the molten iron is:
In vivo, chymotrypsin is a proteolytic enzyme (serine protease) acting in the digestive systems of many organisms. It facilitates the cleavage of peptide bonds by a hydrolysis reaction, which despite being thermodynamically favorable, occurs extremely slowly in the absence of a catalyst. The main substrates of chymotrypsin are peptide bonds in which the amino acid N-terminal to the bond is a tryptophan, tyrosine, phenylalanine, or leucine. Like many proteases, chymotrypsin also hydrolyses amide bonds in vitro, a virtue that enabled the use of substrate analogs such as N-acetyl-L-phenylalanine p-nitrophenyl amide for enzyme assays. Chymotrypsin cleaves peptide bonds by attacking the unreactive carbonyl group with a powerful nucleophile, the serine 195 residue located in the active site of the enzyme, which briefly becomes covalently bonded to the substrate, forming an enzyme-substrate intermediate. Along with histidine 57 and aspartic acid 102, this serine residue constitutes the catalytic triad of the active site. These findings rely on inhibition assays and the study of the kinetics of cleavage of the aforementioned substrate, exploiting the fact that the enzyme-substrate intermediate p-nitrophenolate has a yellow colour, enabling measurement of its concentration by measuring light absorbance at 410 nm. Chymotrypsin catalysis of the hydrolysis of a protein substrate (in red) is performed in two steps.
In December 1987, John Philp Thompson Sr., the chairman and CEO of 7-Eleven, completed a $5.2 billion management buyout of the company. The buyout suffered from the effects of the 1987 stock market crash and after failing initially to raise high yield debt financing, the company was required to offer a portion of stock as an inducement to invest in the company's bonds. Various assets, such as the Chief Auto Parts chain, the ice division, and hundreds of store locations, were sold between 1987 and 1990 to relieve debt incurred during the buyout. This downsizing also resulted in numerous metropolitan areas losing 7-Eleven stores to rival convenience store operators. In October 1990, the heavily indebted Southland Corp. filed a pre-packaged Chapter 11 bankruptcy in order to transfer control of 70% of the company to Japanese affiliate Ito-Yokado. Southland exited bankruptcy in March 1991, after a cash infusion of $430 million from Ito-Yokado and Seven-Eleven Japan. These two Japanese entities now controlled 70% of the company, with the founding Thompson family retaining 5 percent. In 1999, Southland Corp. changed its name to 7-Eleven, Inc., citing the divestment of operations other than 7-Eleven. In 2005, Seven-Eleven Japan made a tender offer and 7-Eleven, Inc. became its wholly owned subsidiary. In 2007, Seven & I Holdings announced that it would be expanding its U.S. operations, with an additional 1,000 7-Eleven stores in the U.S. For the 2010 rankings, 7-Eleven climbed to the No.
In 1917, before the revolution, health conditions were significantly behind those of developed countries. As Lenin later noted, "Either the lice will defeat socialism, or socialism will defeat the lice". The Soviet health care system was conceived by the People's Commissariat for Health in 1918. Under the Semashko model, health care was to be controlled by the state and would be provided to its citizens free of charge, a revolutionary concept at the time. Article 42 of the 1977 Soviet Constitution gave all citizens the right to health protection and free access to any health institutions in the USSR. Before Leonid Brezhnev became general secretary, the Soviet healthcare system was held in high esteem by many foreign specialists. This changed, however, from Brezhnev's accession and Mikhail Gorbachev's tenure as leader, during which the health care system was heavily criticized for many basic faults, such as the quality of service and the unevenness in its provision. Minister of Health Yevgeniy Chazov, during the 19th Congress of the Communist Party of the Soviet Union, while highlighting such successes as having the most doctors and hospitals in the world, recognized the system's areas for improvement and felt that billions of rubles were squandered. After the revolution, life expectancy for all age groups went up. These improvements continued into the 1960s when statistics indicated that the life expectancy briefly surpassed that of the United States; life expectancy started to decline in the 1970s, possibly because of alcohol abuse.
Experimental gene therapy exists to treat hereditary spherocytosis in lab mice; however, this treatment has not yet been tried on humans due to all of the risks involved in human gene therapy. Bone marrow transplant. Paradoxical endurance-based athleticism associated with hereditary spherocytosis. Evolution of spherocytic erythrocyte adaptation in those of Northern European and Japanese descent. Increased ability to defend against viral infections in hereditary spherocytosis patients.
Sources: en.wikipedia.org
Sigma RBI produces specialized products for use in the field of cell signaling and neuroscience. Their offerings range from standard biochemical reagents to specialized research tools, including ligands for receptors and ion channels, enzyme inhibitors, phosphospecific antibodies, key signal transduction enzymes, and assay kits for cell signaling.
=== Size === The smallest bat, and one of the smallest mammals, is Kitti's hog-nosed bat (Craseonycteris thonglongyai), which is 29–33 mm (1+1⁄8–1+1⁄4 in) long with a 150-millimetre (6 in) forearm and weighs 2 oz (56+11⁄16 g). The largest species is the giant golden-crowned flying fox (Acerodon jubatus), which can weigh 1.5 kg (3+1⁄4 lb) with a wingspan of 1.6 m (5 ft 3 in). Larger bats tend to use lower frequencies and smaller bats higher for echolocation; high-frequency echolocation is better at detecting smaller prey. Small prey may be absent in the diets of large bats as they are unable to detect them.
=== Off-label promotion === Although some small, non-controlled studies in the 1990s—mostly sponsored by gabapentin's manufacturer—suggested that treatment for bipolar disorder with gabapentin may be promising, the preponderance of evidence suggests that it is not effective.
== Medical uses == Terlipressin is indicated to improve kidney function in adults with hepatorenal syndrome with rapid reduction in kidney function. Indications for use include norepinephrine-resistant septic shock although, 2021 Surviving Sepsis Guidelines recommend against its use for adults with septic shock and hepatorenal syndrome. In addition, it is used to treat bleeding esophageal varices.
A certain tendency of the press of the time to fall into anti-Peruvian positions has also been documented, as an example are newspapers that satire and mock the monarchist doctrines of the Royal Army of Peru while justifying the arbitrary annexation of Guayaquil, another case are the newspapers Ecuadorians who belittled the death of the Peruvian caudillo José de la Mar compared to that of the Venezuelan Simon Bolívar. Ecuador's territorial conflicts with Peru date back to the first days of independence, since the construction of the borders of the states through respect for the principle of Uti Possidetis Jure, that is, the borders imposed by the colonial administration on their respective legal-administrative entities (viceroyalties), had the problem of ambiguity for this area for the year 1810 and the existence of a royal decree of the year 1802 transferring these territories from Quito to Peru; Given this, they agreed to submit the matter to the arbitration of the King of Spain (even tripartite proposals with Colombia were considered). During the Peruvian-Ecuadorian War of 1858–1860, the figure of Gabriel García Moreno was accused of promoting, in his conception of Ecuadorian patriotism, anti-Peruvianism, Catholic fanaticism and rancor towards the soldiery. The development of a certain Ecuadorian anti-Peruvianism, something clearly known in Chile and in Peru itself, prompted Chile, through the diplomat Joaquín Godoy, to try to open a "second front" to Peru in the War of the Pacific.
Sources: en.wikipedia.org
Yes, the terms are generally interchangeable. Lyophilization is more common in pharmaceutical and laboratory contexts, while freeze-drying appears widely in food science and general writing. Both describe removal of solvent by sublimation under vacuum after freezing.
Reduced pressure keeps the process below the triple point of water, so ice can sublimate directly to vapor. It also lowers the temperature needed for drying, which helps preserve heat-sensitive materials. Without vacuum, melting or boiling could occur instead of controlled sublimation.
The rate depends on heat transfer to the product and mass transfer of vapor through the dried layer. A cold condenser, adequate vacuum, and suitable shelf temperature all influence speed. Formulation properties such as solid content and collapse temperature also set practical limits.
Lyophilization relies on sublimation, so water moves from solid ice to vapor without becoming liquid. The material is frozen, pressure is reduced, and controlled heat is supplied. Vapor is captured on a cold condenser, leaving a dry porous solid.