sublimation 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.
Last reviewed on 2026-01-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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 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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying; lyophilisation; cryodesiccation | Regional spelling and historical terms. |
| Primary drying pressure | 0.05-0.5 mbar (5-50 Pa) | Kept below the triple point of water; product-specific. |
| Shelf temperature range | -40 to +40 °C | Freezing, primary, and secondary stages use different set points. |
| Cycle duration | 12-72 hours | Depends on fill volume, formulation, and equipment. |
| Condenser temperature | -50 to -80 °C | Must remain below the product's ice temperature. |
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.
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.
Dialkylbiaryl phosphine ligands are air-stable solids. Many are available commercially. They often can be synthesized in from inexpensive starting materials. One pot protocols have been conducted on >10 kilograms (22 lb) scales.
== Metabolism and derivatives == 14-Hydroxycaryophyllene oxide (C15H24O2) was isolated from the urine of rabbits treated with (−)-caryophyllene (C15H24). The X-ray crystal structure of 14-hydroxycaryophyllene (as its acetate derivative) has been reported. The metabolism of caryophyllene progresses through (−)-caryophyllene oxide (C15H24O) since the latter compound also afforded 14-hydroxycaryophyllene (C15H24O) as a metabolite.
Going hitless in 16 at bats during the World Series that fall, in addition to his feud with manager Dick Williams over lack of playing time, resulted in the Athletics fulfilling his trade demand by sending him to the Texas Rangers for Horacio Piña on December 1, 1972. Additionally, the A's wanted to free up the first base position for Gene Tenace who was the star of that same Fall Classic. Opening 1973 batting .188 with one homer and six RBIs, he was dealt along with Rich Hand and Rick Stelmaszek from the Rangers to the California Angels for Jim Spencer and Lloyd Allen on May 20. In 1973, he was seventh in the league in hit by pitches (8). On May 4, 1974, he was released by the Angels. In 907 games over nine seasons, Epstein posted a .244 batting average (695-for-2,854) with 362 runs, 130 home runs, 380 RBIs, 448 bases on balls, .358 on-base percentage and .424 slugging percentage. He finished his career with a .991 fielding percentage playing every inning at first base. In 13 postseason games, he hit only .108 (4-for-37) with two runs scored, one home run, one RBI, and nine walks. In 1991 he was inducted into the Southern California Jewish Sports Hall of Fame. He was inducted as a member of the United States National Jewish Sports Hall of Fame in 2004. Through 2010, he was sixth all-time in career home runs (behind Mike Lieberthal) among Jewish major league baseball players.
Sources: en.wikipedia.org
In this process, rare-earth ions are adsorbed onto suitable ion-exchange resin by exchange with hydrogen, ammonium or cupric ions present in the resin. Lutetium salts are then selectively washed out by suitable complexing agent. Lutetium metal is then obtained by reduction of anhydrous LuCl3 or LuF3 by either an alkali metal or alkaline earth metal.
The following is a list of episodes from the series CID aired from 2010 to 2014. For episodes aired from 1998 to 2009, see the List of CID episodes: 1998–2009. For episodes aired from 2015 to 2018, see the List of CID episodes: 2015–2018.
The lists of Merriam-Webster's Words of the Year (for each year) are ten-word lists published annually by the American dictionary-publishing company Merriam-Webster, Inc., which feature the ten words of the year from the English language. These word lists started in 2003 and have been published at the end of each year. At first, Merriam-Webster determined its contents by analyzing page hits and popular searches on its website. Since 2006, the list has been determined by an online poll and by suggestions from visitors to the website. The following is the list of words that became Merriam-Webster's Word of the Year since 2003:
Sources: en.wikipedia.org
== Biosynthesis == OPH is created using the precursor 2-aminobutyric acid through consecutive reactions of the same enzymes that create GSH, namely Glutamate–cysteine ligase and glutathione synthetase. Major regulators of OPH biosynthesis are local (relative) concentrations of cysteine and 2-aminobutyric acid, as well as their γ-glutamyl intermediate products.
=== Secondary neoplasm === Development of secondary neoplasia after successful chemotherapy or radiotherapy treatment can occur. The most common secondary neoplasm is secondary acute myeloid leukemia, which develops primarily after treatment with alkylating agents or topoisomerase inhibitors. Survivors of childhood cancer are more than 13 times as likely to get a secondary neoplasm during the 30 years after treatment than the general population. Not all of this increase can be attributed to chemotherapy.
== External links == Pathway at biocarta.com Nosek, Thomas M. "Section 6/6ch2/s6ch2_34". Essentials of Human Physiology. Archived from the original on 2016-03-24. Overview of all the structural information available in the PDB for UniProt: P01282 (VIP peptides) at the PDBe-KB.
Sources: en.wikipedia.org
Simple drying usually removes water by evaporation from a liquid or solid, often with heat. Lyophilization first freezes the material and then removes ice by sublimation under vacuum. This avoids prolonged exposure to liquid water and high temperatures.
Reduced pressure lowers the boiling point of water and allows ice to sublime at temperatures below freezing. It also helps remove water vapor from the product toward the condenser. The exact pressure is chosen to stay below the triple point of water.
No. Materials with low solids content or high volatile solvents may form weak or collapsed cakes. Some proteins and cells require stabilizers to survive freezing and drying stresses. Feasibility depends on formulation and process design.
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.