Lyophilization comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-12-08. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
| 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 |
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.
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.
Algicidal bacteria are a diverse group of bacteria that either directly or indirectly inhibit the growth of algae. They play a key role in maintaining ecological stability in fresh water and marine environments by mitigating the negative effects of harmful algal blooms (HAB). Algicidal bacteria interactions with algal cells can be broadly split into two categories: direct and indirect. Direct methods typically involve the algicidal bacteria physically attacking the algal cell to induce cell lysis. Indirect methods of attack by algicidal bacteria typically involve releasing algae inhibiting chemicals into the surrounding water. Algicidal bacteria can detect targeted algal cells via chemotaxis and quorum sensing. Different species of algicidal bacteria can have varying degrees of specificity and many have co-evolved along their target algae. Algicidal bacteria have been used as a biological control method against HABs. They tend to be more environmentally friendly than traditional algicides.
==== Japan ==== In Japanese cuisine, they are called harusame (春雨), literally "spring rain". Unlike Chinese glass noodles, they are usually made from potato starch. They are commonly used to make salads, or as an ingredient in hot pot dishes. They are also often used to make Japanese adaptations of Chinese and Korean dishes. Shirataki noodles are translucent, traditional Japanese noodles made from the konjac yam and sometimes tofu.
== Epidemiology == Kwashiorkor is rare in high-income countries. It is mostly observed in low-income and middle-income nations and regions such as Southeast Asia, Central America, Congo, Ethiopia, Puerto Rico, Jamaica, South Africa, and Uganda, where poverty is prominent. Occurrences of severe malnutrition also tend to trend higher under conditions of food insecurity, higher prevalence of infectious diseases, lack of access to appropriate care, and poor living situations with inadequate sanitation. Communities experiencing famine are affected the most, especially during the rainy season. Prevalence varies, but it affects children of either sex commonly under five years old. "Globally, kwashiorkor indirected accounted for 53% of deaths among children under five between 2000 and 2003 when associated with other common childhood diseases like acute respiratory infections, malaria, measles, HIV/AIDS and other causes of perinatal deaths." When compared to marasmus in developing countries, kwashiorkor typically has a lower prevalence, "0.2%-1.6% for kwashiorkor and 1.2%-6.8% for marasmus." Factors such as "diet, geographical locations, climate, and aflatoxin exposure" have been invoked as potential causes for observed differences in the prevalence of kwashiorkor and marasmus. In general, in areas where Severe Acute Malnutrition (SAM) is prevalent, marasmus is more often the dominant SAM condition. However, in certain areas, kwashiorkor may be more common than marasmus.
Enzymes that use a metal in the active site are called "metallo-carboxypeptidases" (EC number 3.4.17). Other carboxypeptidases that use active site serine residues are called "serine carboxypeptidases" (EC number 3.4.16). Those that use an active site cysteine are called "cysteine carboxypeptidase" (or "thiol carboxypeptidases")(EC number 3.4.18). These names do not refer to the selectivity of the amino acid that is cleaved.
Sources: en.wikipedia.org
Sick benefits were administered by the subordinate lodges. In 1899 it was limited to the United States and had 3,000 men and 2,500 women members. The orders seal was a spread eagle with a shield holding an American flag and the words "Liberty, Equality, Fraternity" emblazoned on it. Independent Order of B'nai B'rith Independent Order of B'rith Sholom - Founded in 1905 to assist Jewish immigrants to the US. As Jewish immigration increased, it became more of a human rights organization. Membership open to Jews and gentiles over 16. Female auxiliary named B'rith Sholom Women. Had 52,596 members in 1917. Had 20,000 members in 1979. 6,000 members in 1988. Headquarters in 1917 was at 510-512 5th Street, Philadelphia. Headquarters still at Philadelphia in 1979, when the order had 130 lodges and three statewide organizations. They had a secret ritual, but it was only used by a few lodges. Offers scholarships. Did not have an insurance fund, per se, but offered death and burial benefits and financial aid when members were in need; also taught English language and Americanization. The group saved 50 children aged 5 to 14 during the Holocaust; these were housed at a Camp Sholom. Operates a retirement home in Philadelphia that housed 500. Sponsors Albert Einstein College of Medicine at Yeshiva University and a recuperation center for Israeli soldiers in Haifa. Contributed a 65-acre (26 ha) tract of land for Eagleville Sanatorium.
=== Chemoresistance === In some cases, the characteristics of CAF provide therapeutic resistance. Soluble factor resistance occurs when CAF either directly secrete signals (cytokines or growth factors) or influence the cells around them to give off similar signals, which reduce the efficacy of therapeutic drugs. For instance, this can either be done by an increased secretion of antiapoptotic factors or by altering the cell environment (e.g. pH) to counteract the actions of the drug. Another form is cell adhesion- mediated drug resistance. This involves the tight attachment of neoplastic cells to the extracellular matrix or stromal cells. For example, secretion of TGF-beta allows cancerous cells to bind more successfully to the extracellular matrix thus evading the action of some cancer drugs.
Because so many chloroplast genes have been moved to the nucleus, many proteins that would originally have been translated in the chloroplast are now synthesized in the cytoplasm of the plant cell. These proteins must be directed back to the chloroplast, and imported through at least two chloroplast membranes. Curiously, around half of the protein products of transferred genes aren't even targeted back to the chloroplast. Many became exaptations, taking on new functions like participating in cell division, protein routing, and even disease resistance. A few chloroplast genes found new homes in the mitochondrial genome—most became nonfunctional pseudogenes, though a few tRNA genes still work in the mitochondrion. Some transferred chloroplast DNA protein products get directed to the secretory pathway, though many secondary plastids are bounded by an outermost membrane derived from the host's cell membrane, and therefore topologically outside of the cell because to reach the chloroplast from the cytosol, the cell membrane must be crossed, which signifies entrance into the extracellular space. In those cases, chloroplast-targeted proteins do initially travel along the secretory pathway. Because the cell acquiring a chloroplast already had mitochondria (and peroxisomes, and a cell membrane for secretion), the new chloroplast host had to develop a unique protein targeting system to avoid having chloroplast proteins being sent to the wrong organelle.
The term "Arch" is derived from Greek ἀρχή (archē, 'authority') that is to say it means "chief". 'Purple' comes from one of the colours, mentioned in the Bible, which were used to make the curtains of the tabernacle (the others being Blue/Indigo and Scarlet). Some claim it is of Masonic origin; The "Diamond Boys" from North Armagh - Sloan, Winter and Wilson from the neighbouring Dyan in County Tyrone were all Freemasons. Wilson had asked his own Masonic lodge to give active help in repelling the Defenders (Ireland) and they refused, almost certainly saying that that would be against Masonic principles. As a result of that refusal and left without any alternative after the Battle of the Diamond the four men formed the Orange Order. They had no other template on which to base the proposed ritual and procedure but that of Freemasonry. That is why Orange ritual and most particularly Arch Purple ritual somewhat resembles that of Freemasonry. In fact it is so close that the Arch Purple can be considered to be a Protestant form of Freemasonry. although this has been repeatedly disputed, with overwhelming evidence proving the degree to be descended from the Orange Boys of the Dyan (prevalent around the early 1790s), which in turn based their degrees on the early Boyne Societies which dated from the late 17th century. The Royal Arch Purple Degree itself is constructed along Christian lines, with Christian faith, hope and charity being commended to the new brother.
==== Other milestones (2002–03) ==== For the first three months of the 2002 season, Bagwell labored greatly with throwing; he still had not fully recovered from offseason shoulder surgery. Even after the shoulder improved, it was noticeably weaker than two years prior. In July, he batted .349 with six home runs and 23 RBI. Before a game against the San Diego Padres on August 27, he met with an 11-year-old bone cancer patient named Stephen Rael who asked him to hit a home run for him. Bagwell replied, "I'm going to try, but I'm not Babe Ruth." In the fifth inning, he hit a pitch from Mike Bynum over the left field wall and pointed to the child in the stands as he rounded third base. He later said, "I hit the home run, and he felt it was for him. I'm glad for that. It made it special." From August 10–24, Bagwell produced a season-high 15-game hitting streak, marking the 12th consecutive season with at least one double-digit hit streak, a club record, and second to Roberto Alomar with 14 among all then-active players. In September, he batted .343 with 11 multiple-hit games. During a 3–2 loss to the Montreal Expos on April 26, 2003, Bagwell's infield single gave him 2,000 hits for his career, joining Biggio as the only Astro to achieve this mark. Bagwell collected the assist for the final out of a combined no-hitter and 8–0 win over the Yankees on June 11. He scooped a ground ball batted from Hideki Matsui and relayed it to Billy Wagner covering first base, the final of a record six pitchers participating in the feat.
Sources: en.wikipedia.org
Around 1980, Geneviève Meurgues conserved the hull of the Roman boat found under the construction site of the Stock Exchange shopping center in Marseille, using freeze-drying and resinous injection techniques. The conserved boat is on display at the Marseille History Museum.In 1985 she was awarded the Prix Jean-Perrin for her work to popularise science. From 1988, she devoted herself to the development of grande galerie de l'évolution du Muséum national d'histoire naturelle at the National Museum of Natural History. She worked on the choice of specimens, the interpretation and writing of scientific texts and the synopses and screen plays for documentary films, as well as designing games for the gallery. Meurgues was promoted to professor of the Museum in 1992. The grande galerie de l'évolution was opened on 21 June 1994, the day of the summer solstice, by President François Mitterrand. Meurgues escorted him through the gallery. Geneviève Meurgues worked as the deputy director of the Grande Galerie de l'Évolution until her retirement in 1998.
In botany, apical dominance is the phenomenon whereby the main, central stem of the plant is dominant over (i.e., grows more strongly than) other side stems; on a branch the main stem of the branch is further dominant over its own side twigs. Plant physiology describes apical dominance as the control exerted by the terminal bud (and shoot apex) over the outgrowth of lateral buds.
Actinides easily react with halogens forming salts with the formulas MX3 and MX4 (X = halogen). So the first berkelium compound, BkCl3, was synthesized in 1962 with an amount of 3 nanograms. Like the halogens of rare earth elements, actinide chlorides, bromides, and iodides are water-soluble, and fluorides are insoluble. Uranium easily yields a colorless hexafluoride, which sublimates at a temperature of 56.5 °C; because of its volatility, it is used in the separation of uranium isotopes with gas centrifuge or gaseous diffusion. Actinide hexafluorides have properties close to anhydrides. They are very sensitive to moisture and hydrolyze forming AnO2F2. The pentachloride and black hexachloride of uranium were synthesized, but they are both unstable. Action of acids on actinides yields salts, and if the acids are non-oxidizing then the actinide in the salt is in low-valence state:
=== Mechanism of action === Albiglutide acts as an agonist at the GLP-1 receptor, which makes it a type of incretin mimetic. This causes an increase of insulin secretion, predominantly in the presence of high blood glucose, and also slows down gastric emptying. Unlike other GLP-1 agonists, due to its structure it has difficulty in crossing the blood-brain barrier. This means that it does not affect the central nervous system as much as other GLP-1 agonists and may be responsible for the limited weight loss seen in the drug.
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 water from a material, while lyophilization freezes the material and removes water by sublimation under vacuum. This avoids the liquid phase and reduces thermal damage to sensitive substances. The result is a porous cake that reconstitutes quickly.