If you have been reading about Sublimation and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-11-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
| Property | Value | Notes |
|---|---|---|
| Common name | Freeze-drying | Lyophilization is the technical synonym. |
| Typical chamber pressure | 0.01–0.1 mbar | Below the triple point of water. |
| Primary drying temperature | −40 to −10 °C | Depends on formulation and equipment. |
| Residual moisture | 1–5% | Target for many pharmaceutical products. |
| Typical equipment | Vacuum freeze-dryer | Includes drying chamber and condenser. |
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.
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.
== Culinary uses == Sirloin steak has many culinary uses. It is typically cooked using dry-heat methods, such as grilling, broiling or pan-searing. The sirloin steak cut may be served as a steak, or as a component of dishes such as kebabs, stir-fries and sandwiches where it is cut into smaller portions.
An anaerobic organism or anaerobe is an organism that does not require molecular oxygen for growth or energy metabolism. Anaerobes produce adenosine triphosphate (ATP) by fermentation, anaerobic respiration, or both. During anaerobic respiration, substances other than oxygen serve as the terminal electron acceptor. Anaerobes are commonly classified according to their relationship with oxygen. Obligate anaerobes are harmed by it. Aerotolerant organisms do not use oxygen but can tolerate it, whereas facultative anaerobes can grow without oxygen but use it when available. Most anaerobes are microorganisms, including bacteria, archaea, protozoa, and fungi, although a small number of anaerobic multicellular animals are known. Anaerobes occur in oxygen-depleted environments and in symbiotic associations with other organisms. Culturing anaerobes often requires oxygen-free techniques.
A number of people, starting with Gerald Kulcinski in 1986, have proposed to explore the Moon, mine lunar regolith, and use the helium-3 for fusion. Liquid helium-4 can be cooled to about 1 K (−272.15 °C; −457.87 °F) using evaporative cooling in a 1-K pot. Similar cooling of helium-3, which has a lower boiling point, can achieve about 0.2 kelvin in a helium-3 refrigerator. Equal mixtures of liquid 3He and 4He below 0.8 K separate into two immiscible phases due to their dissimilarity (they follow different quantum statistics: helium-4 atoms are bosons while helium-3 atoms are fermions). Dilution refrigerators use this immiscibility to achieve temperatures of a few millikelvins. It is possible to produce exotic helium isotopes, which rapidly decay into other substances. The shortest-lived heavy helium isotope is the unbound helium-10 with a half-life of 2.6(4)×10−22 s. Helium-6 decays by emitting a beta particle and has a half-life of 0.8 seconds. Helium-7 and helium-8 are created in certain nuclear reactions. Helium-6 and helium-8 are known to exhibit a nuclear halo.
=== Nerve cell === Nerve cells comprise a small cell body and a very long segment called the axon. The cell body resides in the spinal cord and the axon extends all the way to the innervation target of the nerve. Peripheral nerve axons can be longer than 100 cm as they may need to travel along the full length of a limb to reach their innervation target, while the cell body is only 100 micrometers long. Nerves may be myelinated or unmyelinated. Myelinated nerves have the axon covered by segments of schwann cells, which are short and concentrically wrapped around the diameter of an axon to give the appearance of a sausage-like mass and called a myelin sheath. The schwann cells are arranged in pattern such all parts of the axon are wrapped in schwann cells and successive schwann cells are separated by a very small distance. This separation gap is called a node of Ranvier. Unmyelinated nerves are also surrounded by schwann cells but the schwann cells are not wrapped around the axon multiple times to form a myelin sheath.
== Clinical trials == Clinical trials for muscular dystrophy have not proven successful in generating functional improvements compared to placebo. Gains of muscle mass were small to non-existent in this population. Research is ongoing on the potential use of myostatin inhibitors for motor neuron diseases like spinal muscle atrophy and amyotrophic lateral sclerosis. Due to myostatin's effect as a negative regulator of bone, its inhibition has also been considered for orthopedic diseases such as rheumatoid arthritis. Myostatin inhibitors were generally able to increase lean body mass and reduce body fat in people with sarcopenia, but the extent to which this translated into functional improvements varied. Bimagrumab showed effectiveness in increasing lean mass and reducing fat mass in obese individuals in a clinical trial.
Sources: en.wikipedia.org
== External links == PDCD1+protein,+human at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Overview of all the structural information available in the PDB for UniProt: Q15116 (Programmed cell death protein 1) at the PDBe-KB. This article incorporates text from the United States National Library of Medicine, which is in the public domain.
==== Oily skin ==== Oily skin is caused by over-active sebaceous glands, that produce a substance called sebum, a naturally healthy skin lubricant. A high glycemic-index diet and dairy products (except for cheese) consumption increase IGF-1 generation, which in turn increases sebum production. Overwashing the skin does not cause sebum overproduction but may cause dryness. When the skin produces excessive sebum, it becomes heavy and thick in texture, known as oily skin. Oily skin is typified by shininess, blemishes and pimples. The oily-skin type is not necessarily bad, since such skin is less prone to wrinkling, or other signs of ageing, because the oil helps to keep needed moisture locked into the epidermis (outermost layer of skin). The negative aspect of the oily-skin type is that oily complexions are especially susceptible to clogged pores, blackheads, and buildup of dead skin cells on the surface of the skin. Oily skin can be sallow and rough in texture and tends to have large, clearly visible pores everywhere, except around the eyes and neck.
== Other mechanisms == In working skeletal muscles and the brain, phosphocreatine is stored as a readily available high-energy phosphate supply, and the enzyme creatine kinase transfers a phosphate from phosphocreatine to ADP to produce ATP. Then the ATP can be utilized for doing useful work by cellular processes. The creatine kinase reaction is sometimes erroneously considered to be substrate-level phosphorylation, although it is a transphosphorylation.
== Description == The mushrooms are orange, yellow or white, meaty and funnel-shaped. On the lower surface, underneath the smooth cap, most species have rounded, forked folds that run almost all the way down the stipe, which tapers down seamlessly from the cap. Many species emit a fruity aroma, reminiscent of apricots, and often have a mildly peppery taste. Cantharellus pallens has sometimes been defined as a species in its own right, but it is normally considered to be just a variety (C. cibarius var. pallens). Unlike "true" C. cibarius it yellows and then reddens when touched and has a weaker smell. Eyssartier and Roux classify it as a separate species but say that 90% of the chanterelles sold in French markets are this, not C. cibarius. Similarly, the very pale C. alborufescens, which reddens easily and is found in Mediterranean areas, and northern of Iran is sometimes distinguished as a separate variety or a separate species.
Sources: en.wikipedia.org
From 1975 to 1980, the Rhodesian government made several attempts to weaponise chemical and biological agents. Members of the security forces contaminated supplies before replacing them in guerrilla caches or planted them in rural stores to be stolen by the guerrillas during raids. They also poisoned water sources along known infiltration routes along the Rhodesian border, forcing their opponents to travel through more arid regions or carry more water during their treks. The chemical agents most used in the Rhodesian chemical and biological warfare (CBW) programme were parathion (an organophosphate insecticide) and thallium (a heavy metal commonly found in rodenticide). The weapons the Rhodesians selected for use also included Vibrio cholerae (causative agent of cholera) and possibly Bacillus anthracis (causative agent of anthrax). They also looked at using Rickettsia prowazekii (causative agent of epidemic typhus), and Salmonella typhi (causative agent of typhoid fever), and toxins such as ricin and botulinum toxin. Biological agents, namely Vibrio cholerae, had some impact on the fighting capability of ZANLA. Some former officers of the Rhodesian Security Forces alleged that anthrax was used covertly during the late 1970s, but this has been disputed. Use of anthracis, ricin, or botulinum toxin was favoured during assassination attempts of prominent guerrilla commanders.
==== MeSH D12.776.467.374.400 – growth substances ==== MeSH D12.776.467.374.400.442 – hematopoietic cell growth factors MeSH D12.776.467.374.400.442.240 – colony-stimulating factors MeSH D12.776.467.374.400.442.240.075 – colony-stimulating factors, recombinant MeSH D12.776.467.374.400.442.240.075.350 – granulocyte colony stimulating factor, recombinant MeSH D12.776.467.374.400.442.240.075.350.275 – filgrastim MeSH D12.776.467.374.400.442.240.075.375 – granulocyte macrophage colony-stimulating factors, recombinant MeSH D12.776.467.374.400.442.240.150 – erythropoietin MeSH D12.776.467.374.400.442.240.150.250 – erythropoietin, recombinant MeSH D12.776.467.374.400.442.240.150.250.250 – epoetin alfa MeSH D12.776.467.374.400.442.240.350 – granulocyte colony-stimulating factor MeSH D12.776.467.374.400.442.240.350.375 – granulocyte colony stimulating factor, recombinant MeSH D12.776.467.374.400.442.240.350.375.275 – filgrastim MeSH D12.776.467.374.400.442.240.375 – granulocyte-macrophage colony-stimulating factor MeSH D12.776.467.374.400.442.240.375.275 – granulocyte macrophage colony-stimulating factors, recombinant MeSH D12.776.467.374.400.442.240.400 – interleukin-3 MeSH D12.776.467.374.400.442.240.500 – macrophage colony-stimulating factor MeSH D12.776.467.374.400.442.240.750 – thrombopoietin MeSH D12.776.467.374.400.442.800 – stem cell factor MeSH D12.776.467.374.400.505 – interleukins MeSH D12.776.467.374.400.505.501 – interleukin-1 MeSH D12.776.467.374.400.505.502 – interleukin-2 MeSH D12.776.467.374.400.505.503 – interleukin-3 MeSH D12.776.467.374.400.505.504 – interleukin-4 MeSH D12.776.467.374.400.505.505 – interleukin-5 MeSH D12.776.467.374.400.505.506 – interleukin-6 MeSH D12.776.467.374.400.505.507 – interleukin-7 MeSH D12.776.467.374.400.505.508 – interleukin-8 MeSH D12.776.467.374.400.505.509 – interleukin-9 MeSH D12.776.467.374.400.505.510 – interleukin-10 MeSH D12.776.467.374.400.505.511 – interleukin-11 MeSH D12.776.467.374.400.505.512 – interleukin-12 MeSH D12.776.467.374.400.505.513 – interleukin-13 MeSH D12.776.467.374.400.505.514 – interleukin-14 MeSH D12.776.467.374.400.505.515 – interleukin-15 MeSH D12.776.467.374.400.505.516 – interleukin-16 MeSH D12.776.467.374.400.505.517 – interleukin-17 MeSH D12.776.467.374.400.505.518 – interleukin-18 MeSH D12.776.467.374.400.800 – transforming growth factor beta
The fentanyl supply chain in Mexico consists of a vast and elusive network, potentially involving hundreds of players. U.S. and Mexican anti-narcotics officials acknowledge that the exact number is unknown. Some brokers operate as specialists within major cartels, while others act independently. A major challenge in disrupting this trade lies in the global chemical industry. Many of the compounds used to manufacture fentanyl have legitimate industrial applications, classifying them as dual-use chemicals. These substances are often unregulated or only lightly controlled in key countries such as the United States, Mexico, and China. This regulatory gap enables brokers to evade detection, navigating between the legal chemical trade and the illicit drug market to acquire the necessary precursors. Several large quantities of illicitly produced fentanyl have been seized by U.S. law enforcement agencies. In November 2016, the DEA uncovered an operation making counterfeit oxycodone and Xanax from a home in Cottonwood Heights, Utah. They found about 70,000 pills in the appearance of oxycodone and more than 25,000 in the appearance of Xanax. The DEA reported that millions of pills could have been distributed from this location over the course of time. The accused owned a tablet press and ordered fentanyl in powder form from China. A seizure of a record amount of fentanyl occurred on 2 February 2019, by U.S. Customs and Border Protection in Nogales, Arizona.
=== Individual national championships === A number of notable individuals have also won national championships in the NCAA. Arizona's first NCAA Individual Champion in the sport of Men's Swimming came in 1981 when Doug Towne won the 500-yard freestyle at the NCAA championships. Another individual champion occurred in 1989 when Mariusz Podkoscielny won the 1650-yard (mile) at the NCAA National Championships held at the IUPUI Natatorium. Some other champion swimmers include Crissy Ahmann-Leighton, Ryk Neethling, Margo Geer, Kevin Cordes, and Amanda Beard. Annika Sörenstam won in 1991 in golf, and Brigetta Barrett won the women's high jump in 2013. The men's cross country has also produced two individual national titles in 1986 (Aaron Ramirez) and 1994 (Martin Keino) (NCAA Men's Cross Country Champions). The women's cross country also produced two individual national titles in 1996 (Amy Skieresz) and 2001 (Tara Chaplin) (NCAA Women's Cross Country Championship). Another notable individual was football standout Vance Johnson who won the NCAA long jump in 1982.
=== Chemistry === Catenation, the bonding of atoms of the same element in a series, or chain Polymer chain, structure of a polymer Chain reaction, a sequence of reactions where a reactive product or by-product causes additional reactions Ideal chain, a mathematical model of polymer folding Worm-like chain, a model in polymer physics used to describe the behavior of semi-flexible polymers
Sources: en.wikipedia.org
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.
A vacuum lowers the pressure below the triple point of water, allowing ice to sublimate directly into vapor without melting. It also removes water vapor from the product chamber and speeds up the drying process. Without vacuum, the ice would melt rather than sublimate.
Not all substances are suitable for lyophilization. Materials must form a stable frozen matrix and tolerate freezing and low pressure. Some small molecules, oils, or volatile compounds may not form a proper cake or may be lost during processing.
Yes. Lyophilization and freeze-drying are synonyms for the same vacuum-assisted sublimation process. The term lyophilization is more common in pharmaceutical and laboratory settings, while freeze-drying is widely used in food and general contexts.