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 2025-09-11. 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.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
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.
| 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. |
After primary drying, secondary drying removes water that remains bound to the material. This stage raises the shelf temperature while maintaining low pressure, which encourages desorption of unfrozen water. Residual moisture can be reduced to a low percentage, improving stability for many products. The process parameters, including freezing rate, shelf temperature, and chamber pressure, influence the final pore structure and reconstitution behavior. Control of these variables helps prevent collapse or meltback during drying.
A formulation often contains excipients that protect the active ingredient during freezing and drying. Bulking agents provide structure, while lyoprotectants stabilize sensitive molecules. The freezing step can produce ice crystals whose size and distribution affect the drying rate, and cycle design includes freezing, annealing, and drying phases. If the product temperature rises above a critical value, the cake may collapse or lose its porous structure. Successful lyophilization therefore depends on the interaction between formulation, equipment, and cycle design.
Reconstitution involves adding a suitable diluent, often sterile water or a buffer, to the dried cake. Gentle swirling or inversion helps dissolve the material without creating excessive foam. The time required for complete dissolution can range from seconds to several minutes and depends on the cake structure and the diluent. Improper reconstitution, such as vigorous shaking or using the wrong diluent, can cause protein aggregation or loss of activity. After reconstitution, the product may have a limited shelf life and should be used according to its labeling.
Lyophilized products are typically hygroscopic and require protection from moisture during storage. Manufacturers seal them in glass vials, often under vacuum or an inert gas such as nitrogen. The container closure system, including the stopper and crimp seal, must prevent water vapor ingress. Storage temperature varies from controlled room temperature to refrigerated or frozen conditions, depending on the formulation. Humidity-controlled environments are essential because even brief exposure to ambient air can degrade the product.
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.
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.
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.
Residual moisture is a key quality attribute for lyophilized products. Water that remains after secondary drying can affect chemical stability, cake structure, and shelf life. Karl Fischer titration is a common method for measuring water content in the dried solid. The target range varies by product, but many biologics are dried to between 0.5% and 3% water by weight. Acceptable limits are set during development and confirmed by stability studies.
Most of the diets associated with the reports of non-hereditary DCM have legume seed ingredients, also called "pulses" (e.g., peas, lentils, etc.), high in their ingredient lists ... these include both "grain-free" and grain-containing formulations. Legumes, including pulse ingredients, have been used in pet foods for many years, with no evidence to indicate they are inherently dangerous, but analysis of data reported to the Center for Veterinary Medicine indicates that pulse ingredients are used in many "grain-free" diets in greater proportion than in most grain-containing formulas. FDA has asked pet food manufacturers to provide diet formulations so we can further understand the proportions of ingredients in commercially-available diets and possible relationships with non-hereditary DCM. The FDA does not know the specific connection between these diets and cases of non-hereditary DCM and is continuing to explore the role of genetics, underlying medical conditions, and/or other factors.
β-Carotene (beta-carotene) is an organic, strongly colored red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 carbons. Dietary β-carotene is a provitamin compound, converting in the body to retinol (vitamin A). In foods, it has rich content in carrots, pumpkin, spinach, and sweet potato. It is used as a dietary supplement and may be prescribed to treat erythropoietic protoporphyria, an inherited condition of sunlight sensitivity. β-carotene is the most common carotenoid in plants. When used as a food coloring, it has the E number E160a. The structure was deduced in 1930. Isolation of β-carotene from fruits abundant in carotenoids is commonly done using column chromatography. It is industrially extracted from richer sources such as the algae Dunaliella salina. The separation of β-carotene from the mixture of other carotenoids is based on the polarity of a compound. β-Carotene is a non-polar compound, so it is separated with a non-polar solvent such as hexane. Being highly conjugated, it is deeply colored, and as a hydrocarbon lacking functional groups, it is lipophilic.
=== Natural burial === Natural burial—also called "green burial"—is the process by which a body is returned to the earth to decompose naturally in soil, and in some cases even protect native and endangered wildlife. Natural burial became popularized in the UK in the early 1990s by Ken West, a professional cremator operator for the city of Carlisle, responding to the U.K's call for changes in government that aligned with the United Nations' Environmental Program Local Agenda 21. In addition, there are multiple green burial sites in the U.S. Green burials are developing in Canada (Victoria, BC, and Cobourg, Ontario), as well as in Australia and Ireland. The increase in popularity of alternative burials can be seen as a direct choice of the individual's want to distance themselves from religious practices and spiritual locations as well as an opportunity to exercise their act of choice. The desire to live through nature as well as concern for the environment have been the backbone of the green burial movement. The use of coffins made from alternative materials such as wicker and biodegradable materials as well as trees and other flora are being used in place of headstones. Both practices provide sustainable alternatives to traditional burial practices. Natural burials have been attracting people for reasons outside of environmental and sustainability factors as well. With the expansion of urban centres, ecological corridors gradually disappear. Cemeteries for burial plots preclude alternative uses of the land for a long time.
== Contraindications == Apomorphine is contraindicated when used concomitantly with serotonin 5-HT3 receptor antagonists, including ondansetron, granisetron, and palonosetron, as this combination has been associated with profound hypotension and loss of consciousness. It is also contraindicated with allergies to the drug or its excipients, including sulfites. Intravenous administration of apomorphine is associated with blood clots and pulmonary embolism due to crystallization in the vein and is not recommended.
=== 2003–2005: G-Unit, Shady, Aftermath vs. Murder Inc. === During most of 2002, 50 Cent would leak several mixtapes during his brief residence in Canada following his rejection by countless major labels across New York City. One of these mixtapes Guess Who's Back? had found its way to Eminem's attorney Paul Rosenberg. The single "Wanksta" was a subliminal diss aimed at Ja Rule, which ultimately managed to impress Eminem into including the song on the soundtrack to his film 8 Mile later that same year. The success of Wanksta, and Eminem's admiration for 50 Cent's output would culminate in him being signed to Shady/Aftermath for $1 million by both Eminem and Dr. Dre in late 2002. During this time; Murder Inc. Co-founder Irv Gotti further ignited tensions following the publicity around 50 Cent's record deal with Aftermath. Gotti alleged that Jackson had placed an order of police protection against various Murder Inc. affiliates in the wake of the brawl in March 2000. Public attention began to shift as it was discovered that the New York City Police Department had temporarily authorized a restraining order during Black Child's not guilty plea in due to his charges in connection with the stabbing incident. The verbal attack by Gotti and Ja Rule was widely believed to be a stunt to promote his upcoming album The Last Temptation, which was due for release in November 2002. 50 Cent would later capitalize on the incident; leaking the G-Unit diss track I Smell Pussy shortly afterwards. Murder Inc.
Sources: en.wikipedia.org
== Water source == Lake Afdera is fed by numerous hot springs around the lake and, possibly, by underwater springs. The waters of lake Afdera are saline but do not come from the sea. The continental waters gained their salinity by hydrothermal reactions with evaporites and basalts in the underground. The lake level varied significantly in the last tens of thousands of years. During the African Humid Period, the lake level was 50m higher than today and covered much larger area. Since the 1960s' the lake level constantly fluctuated, but these variations were probably less than one meter in amplitude. This suggest that the lake level is controlled by climate and precipitations on the Ethiopian plateau or in the Danakil Alps.
==== Xbox reception ==== The Xbox edition received mixed reviews from critics in comparison to the original game. On the topic of graphics, Matthew Kato from Game Informer wrote that there were "graphical updates here and there" and mentioned the game's inclusion of weather. Greg Kasavin of GameSpot felt that the visuals weren't extraordinary and not enough to make the game "good-looking". IGN's Aaron Boulding mentioned that they were "the biggest disappointment". He commented that the environments were noteworthy in design, but "not in their overall look and level of detail". The AI technology was a surplus for the Xbox edition, because of critics praising for its human-like behavior. Kato mentioned that the bot AI contained some "human-esque traits" and that it would start to understand the map after some rounds. Kasavin found it surprising that the bots weren't following real-life tactics of terrorists or counter-terrorists, but rather mimic the actions of a player. He pointed out that they would camp at a certain place and follow the orders of a player, such as following them or holding a position. Many critics also highlighted Xbox Live as one of the main reasons to purchase the game. Kasavin noted that it runs properly, with hosted matches able to hold 10 players. Boulding expressed that "online play over Xbox Live is going to be the greatest reason to buy this game" and that it's convenient.
Many local effects can influence ice δD in addition to temperature. These effects include moisture origin and transport pathways, evaporation conditions and precipitation seasonality, which can be accounted for in more complicated models. Nevertheless, the Vostok ice core record shows some very important results: (1) A consistent δD depletion of ~70‰ during the last four glacial periods compared to interglacial times, corresponding to a cooling of 8°C in Antarctica; (2) A consistent drop of atmospheric CO2 concentration by 100 ppmv and CH4 drop by ~300 ppbv during glacial times relative to interglacials, suggesting a role of greenhouse gases in regulating global climate; (3) Antarctic air temperature and greenhouse gas concentration changes precede global ice volume and Greenland air temperature changes during glacial terminations, and greenhouse gases may be an amplifier of insolation forcing during glacial-interglacial cycles. Greenland ice core isotope records, in addition to showing glacial-interglacial cycles, also shows millennial-scale climate oscillations that may reflect reorganization in ocean circulation caused by ice melt charges. There have also been ice core records generated in alpine glacials on different continents. A record from the Andes Mountains in Peru shows a temperature decrease of 5-6°C in the tropics during the last ice age. A record from the Tibetan plateau shows a similar isotope shift and cooling during the last ice age.
==== Aspartic acid ==== Aspartic acid (aspartate) is one of the most common amino acids in the typical diet. As with methanol and phenylalanine, intake of aspartic acid from aspartame is less than would be expected from other dietary sources. At the 90th percentile of intake, aspartame provides only between 1% and 2% of the daily intake of aspartic acid.
Sources: en.wikipedia.org
Rhodium (from Greek: ῥόδον rhodon, meaning 'rose') was discovered in 1803 by William Hyde Wollaston, soon after he discovered palladium. He used crude platinum ore presumably obtained from South America. His procedure started by dissolving the ore in aqua regia, precipitating the platinum as ammonium chloroplatinate by adding ammonium chloride (NH4Cl). Adding zinc precipitated a mixture of copper, lead, palladium, and rhodium. Dilute nitric acid dissolved the copper and lead. Dissolving the remainder in aqua regia again and adding sodium chloride, the solution was evaporated to yield rose-red Na3[RhCl6]·nH2O. After extraction with hot ethanol, additional zinc displaced the rhodium in the ionic compound, releasing the rhodium as free metal. For decades, the rare element had only minor applications; for example, by the turn of the century, rhodium-containing thermocouples were used to measure temperatures up to 1800 °C. They have exceptionally good stability in the temperature range of 1300 to 1800 °C. The first major application was electroplating for decorative uses and as corrosion-resistant coating. The introduction of the three-way catalytic converter by Volvo in 1976 increased the demand for rhodium. The previous catalytic converters used platinum or palladium, while the three-way catalytic converter used rhodium to reduce the amount of NOx in the exhaust.
Methods similar to those first developed by Roselius have continued to dominate, and are sometimes known as the direct organic solvent method. However, because of health concerns regarding benzene (which is recognized today as a carcinogen), other solvents, such as dichloromethane or ethyl acetate, are now used. The unroasted (green) beans are first steamed and then rinsed with the solvent which extracts the caffeine, while leaving other constituents largely unaffected. The process is repeated between 8 and 12 times until the caffeine content meets the required standard (97% of caffeine removed according to the US standard, or 99.9% caffeine-free by mass per the EU standard).
Cardiovascular agents are drugs used to treat diseases associated with the heart or blood vessels. These medications are available for purchase only with a physician's prescription. They include, but are not limited to, drugs that target hypertension (antihypertensives), hyperlipidemia (antihyperlipidemics) and blood clotting (blood-thinners) to reduce the risk of cardiovascular diseases. Antihypertensive agents are classified according to their mechanism of actions. The most common classes prescribed are diuretics, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), calcium channel blockers (CCBs) and beta-blockers. Antihyperlipidemic agents most often prescribed are statins, ezetimibe and fibrates. They either lower low-density lipoprotein cholesterol (LDL-C) or triglyceride (TG) levels in blood to manage hypercholesterolaemia. Blood-thinning agents, particularly antiplatelets and anticoagulants, maintain smooth blood flow by preventing blood clot formation in blood vessels. Two main categories of antiplatelets are COX-1 inhibitors and ADP receptor inhibitors, while anticoagulants include vitamin K antagonists, direct oral anticoagulants (DOACs) and indirect thrombin inhibitors. Since cardiovascular agents have narrow therapeutic windows, a slight rise in dose may result in severe toxicity. Hence, monitoring at baseline and during therapy is needed. For drug overdose, stabilisation and antidotes help lower drug concentrations.
The Hassuna culture is a Neolithic archaeological culture in northern Mesopotamia dating to the early sixth millennium BC. It is named after the type site of Tell Hassuna in Iraq. Other sites where Hassuna material has been found include Tell Shemshara.
=== Trivehexin precursor === Like most precursors used for radiolabeling with radioactive metal cations, Trivehexin is composed of a dedicated complex ligand (a so-called chelator) for kinetically inert binding of the 68GaIII ion, and the bioligand(s) for binding to αvβ6-integrin. The chelator comprised in Trivehexin is a triazacycloalkane with 3 phosphinic acid substituents, with the basic structure 1,4,7-triazacyclononane-1,4,7-triphosphinate (frequently abbreviated TRAP). The αvβ6-integrin binding molecular unit is a cyclic nonapeptide with the amino acid sequence cyclo(YRGDLAYp(NMe)K) (INN: relitegatide). In the Trivehexin molecule, three of these cyclopeptides are attached by covalent bonds to a single TRAP chelator core. Since TRAP possesses three equivalent carboxylic acids for conjugation of other molecular units via amide formation, Trivehexin is a C3-symmetrical molecule with its three peptide bioligands being fully equivalent. The peptides are attached to the chelator core via the terminal amine group of the side chains of N-methyl lysine. Actually, the conjugation is not done by amide bonding directly, but involves prior functionalization of the peptide with a short molecular extension (a linker) bearing a terminal alkyne, and of TRAP with three linkers bearing terminal azides. These components are assembled by means of copper(I) catalyzed alkyne-azide cycloaddition (CuAAC, also known as Huisgen reaction, a Click chemistry reaction), giving rise to the three 1,3-triazole linkages in the 68Ga-Trivehexin structure.
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.
Most lyophilized products are stored in sealed containers at controlled temperature and humidity. Some require refrigeration, while others are stable at room temperature. Protection from light and moisture is often necessary.