This is a working overview of sublimation, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-17. Anything still debated is marked as such rather than presented as settled.
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.
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.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen to convert liquid water into ice. Next, the pressure is reduced below the triple point of water so that ice changes directly into vapor without passing through a liquid phase. This step is called primary drying. The result is a porous solid or cake that retains the original shape of the frozen solution.
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.
| 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. |
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 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.
== Chemical composition == The chemical composition of soy sauce is affected by the proportions of raw materials, fermentation methodologies, fermenting molds and strains, and post-fermentation treatments. Although the formation mechanism of chemical composition in soy sauce is complex, it has been widely accepted that free amino acids, water-soluble peptides and Maillard reaction products in soy sauce are considered as essential chemical composition and to provide core sensory effects. The primary fermentation of lactic-acid-fermenting halophiles lowers the pH of the moromi, and this directly results in the acidic pH range (4.4–5.4) of soy sauce products. The secondary fermentation conducted by heterofermentative microbes provides soy sauce with a wide range of flavor and odorant compounds by breaking down macronutrients. Soy proteins and grain proteins are hydrolyzed into short peptide chains and free amino acids, which adds umami to the product. Based on the result of free amino acid analysis, the most abundant amino acids in Chinese soy sauce product are glutamic acid, aspartic acid, alanine and leucine. Starch is hydrolyzed into simple sugars which contribute to the sweet flavor in soy sauce. Legume fats may also be decomposed into short chain fatty acids, and the interactions among lipids and other macronutrients also result in a richer flavor in the final product. Non-enzymatic browning also contributes significantly to the development of the properties of soy sauce.
As part of decolonization, France established the French Union in 1946 and reorganized Indochina in 1949 as a confederation of associated states within it. In June 1949, they united French Cochinchina with the protectorates of Annam and Tonkin to form the State of Vietnam within the French Union, and installed former Emperor Bảo Đại as head of state. The Chinese Communist victory of 1949 changed the nature of the Indochina War. In 1950, the newly established People's Republic of China and the Soviet Union recognized the DRV while the United States recognized the State of Vietnam. The conflict largely resembled a conventional war between two armies equipped with modern weapons, although guerrilla warfare continued to occur in many areas. The United States provided assistance to France, while China assisted the Viet Minh. French Union forces included colonial troops from the empire – North Africans, Sub-Saharan Africans, Laotian, Cambodian and Vietnamese ethnic minorities – and professional French troops, European volunteers, and units of the Foreign Legion. The use of French metropolitan recruits was forbidden by the government to prevent the war from becoming more unpopular at home. It was called the "dirty war" (la sale guerre) by French leftists. In December 1950, France officially established an army for the State of Vietnam. In September 1951, the US began providing direct economic aid to the State of Vietnam. Segments of the population supported neither the communist Viet Minh nor the French colonialists, and were labeled attentistes.
=== Insertion devices === Some pump users prefer to use an insertion device to insert their sets, rather than pushing the needle in by hand. These are spring-loaded and are designed to push the needle into the skin quickly. The user simply loads the primed set into the insertion device, peels off the paper protecting the adhesive pad, places the device against the skin and presses a button. This may be an advantage for those with needle phobia.
=== Site selection and planting === Blackcurrants can grow well on sandy or heavy loams, or forest soils, as long as their nutrient requirements are met. They prefer damp, fertile but not waterlogged ground and are intolerant of drought. Although the bushes are winter hardy, frosts during the flowering period may adversely affect the yield and cold winds may restrict the number of flying insects visiting and pollinating the flowers. A soil pH of about 6 is ideal for blackcurrants and the ground can be limed if the soil is too acidic. Planting is usually done in the autumn or winter to allow the plants to become established before growth starts in the spring, but container-grown stock can be planted at any time of year. Two-year-old bushes are usually planted but strong one-year-old stock can also be used. Planting certified stock avoids the risk of introducing viruses. On a garden scale the plants can be set at intervals of 1.5 to 1.8 m (5 to 6 ft) or they can be set in rows with planting intervals of 1.2 m (4 ft) and row separations of 2.5 m (8 ft) or more. In the UK, young bushes are generally planted deeper than their initial growing level to encourage new stems to grow from the base.
== See also == Body image Eating recovery Evolutionary psychiatry Idée fixe Inedia List of people with anorexia nervosa List of deaths from anorexia nervosa National Association of Anorexia Nervosa and Associated Disorders Muscle dysmorphia Orthorexia nervosa Pro-ana
Sources: en.wikipedia.org
==== 9 April ==== The Israeli airstrikes in Southern Lebanon continued. Hezbollah fired rockets from Lebanon at northern Israel. At around 17:00 Israel Daylight Time, The Jerusalem Post reported that the 98th Division of the IDF had almost fully taken control of all of the town of Bint Jbeil in southern Lebanon. The clashes that ensued would later transform in a full-fledged battle for the city. US President Donald Trump told NBC News that Israel will be "scaling back" its attacks on Lebanon to help support upcoming negotiations between the Iran and the US. Israeli Prime Minister Benjamin Netanyahu instructed his cabinet to begin direct negotiations with Lebanon for peace agreement and demilitarization of Hezbollah. Iran continued to say Israeli attacks "blatantly violate" the ceasefire. A senior Israeli official told Channel 12 that Israel is open to negotiations, but they will take place without a ceasefire. Israel kept striking Hezbollah in Lebanon in a new wave of strikes during the night.
Blood for transfusion is obtained from human donors by blood donation and stored in a blood bank. There are many different blood types in humans, the ABO blood group system, and the Rhesus blood group system being the most important. Transfusion of blood of an incompatible blood group may cause severe, often fatal, complications, so crossmatching is done to ensure that a compatible blood product is transfused. Other blood products administered intravenously are platelets, blood plasma, cryoprecipitate, and specific coagulation factor concentrates.
1999: Established first quantifiable measurement of atractyloside in whole blood with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS); 2001: GC-MS method required derivitization to detect atractyloside fragments; 2004: LC-MS (EI) using Waters Thermabeam detector resulted in complete fragmentation of the molecule; gentler ionization technique (ESI) was successfully used to detect ATR after chromatographic separation; 2006: Further development of procedure with ESI, eluent composition, and other experimental conditions, though still lacking specificity for forensic science. The procedure by Carlier et al. uses high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (HPLC-HRMS/MS). After the extraction of ATR and CATR from the blood or urine sample, separation was performed by reverse-phase HPLC. The MS detection used a quadrupole-orbitrap high-resolution detector after heated electrospray in negative ionization mode. These extraction techniques yielded 71.1% and 48.3% of ATR and CATR, respectively, in which these results met acceptable international criteria for forensic science: precision (≤15% or ≤20% at the LLOQ) and accuracy (between 80 and 115% or 80-120% at the LLOQ). For reference, additional sources have fully characterized atractyloside in NMR, MS, IR, etc.
The incidents began in Jaramana at approximately 2:00 a.m. on 28 April 2025, when an unidentified group opened fire on a local militia checkpoint near the "Al-Naseem" intersection at the entrance of Jaramana. Gunfire continued and intensified around 4:00 a.m., leading to the deaths of at least two members of the security forces and six residents of the city. Over ten others were injured in the initial wave of violence. Local factions imposed heightened security measures, erecting checkpoints and restricting movement into and out of the city. On 29 April 2025, clashes expanded to the Druze-majority towns of Sahnaya and Ashrafiyat Sahnaya. Armed groups attacked multiple security checkpoints using machine guns and RPGs. The fighting briefly paused, but continued after reinforcements arrived from Daraa. Hussam Waruar, the head of the Sahnaya Municipality, was killed along with his son on 1 May by unidentified gunmen. The unidentified groups killed the Druze leader, Wajdi al-Hajj Ali, who was shot in the head and died on 30 April 2025 before reaching the hospital.
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 removes water by sublimation from a frozen material, while evaporation changes liquid water into vapor. The low-pressure freezing step avoids the liquid phase and can preserve heat-sensitive structures.