This is a working overview of sublimation, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-06. Anything still debated is marked as such rather than presented as settled.
Misconceptions about lyophilization include the idea that dried products are indefinitely stable or that vacuum sealing eliminates all degradation. Chemical reactions can continue in the solid state, and some proteins lose activity even at low moisture. Another misconception is that any freeze-dryer cycle can be scaled by time alone; heat and mass transfer differ with equipment and load. Open questions remain about predicting long-term stability from short accelerated studies, particularly for amorphous formulations. Real-time stability data remain the standard for shelf-life assignment.
After lyophilization, the dried product is often sealed under vacuum or an inert gas to limit moisture and oxygen exposure. Vials, stoppers, and seals must maintain their barrier throughout shelf life. Storage temperature depends on product sensitivity: some cakes tolerate controlled room temperature, while labile biologics require refrigeration. Humidity is a critical variable because dried cakes are hygroscopic and can absorb water when exposed to air. Handling procedures therefore limit open-vial time and use desiccated environments for sampling.
Quality control for lyophilized materials examines appearance, reconstitution time, residual moisture, and mechanical integrity. An acceptable cake is usually uniform and porous, though appearance alone does not prove stability. Karl Fischer titration is a common method for water content, while differential scanning calorimetry can reveal glass transition events. Stability studies track potency, aggregation, and moisture over time under defined temperature and humidity conditions. Specifications are product-specific and may include sterility and endotoxin tests for sterile preparations.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | Porous, uniform cake or powder | Collapsed or shrunken cakes indicate process issues. |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity, excipients, and diluent. |
| Residual moisture | 0.5-3% w/w | Product-specific; measured by Karl Fischer titration. |
| Typical storage temperature | 2-25 °C | Some biologics require 2-8 °C. |
| Container closure | Glass vial with elastomeric stopper | Sealed under vacuum or inert gas. |
Stability programs monitor lyophilized products under defined temperature and humidity conditions over time. Real-time studies at recommended storage conditions are the reference, while accelerated studies provide early signals of degradation pathways. Because a dry cake can still undergo oxidation, hydrolysis, or aggregation, stability depends on residual moisture, excipients, and container headspace. Open questions include how best to predict long-term stability from short accelerated runs and how vial-to-vial variability affects shelf life. Current guidance treats these predictions as product-specific rather than universally generalizable.
Freeze-dried materials are hygroscopic to varying degrees and can take up moisture after drying. Storage therefore often uses sealed glass vials, rubber stoppers, and crimp seals to limit contact with ambient humidity. A desiccant may be included for moisture-sensitive products, although it is not universal. Controlled room temperature is sufficient for many lyophilizates, while others require refrigeration or freezing. Moisture ingress remains a primary cause of cake collapse, chemical degradation, and loss of reconstitution performance.
Quality assessment of a lyophilized product includes cake appearance, residual moisture, reconstitution time, and container closure integrity. A uniform, porous cake suggests that freezing and drying stayed within the formulation's design space. Cracks, shrinkage, meltback, or a glassy film can indicate thermal abuse or a formulation problem. Analysts also test for subvisible particles and sterility when the product requires those specifications. Visual inspection alone cannot confirm biological activity or chemical stability, so it is combined with analytical methods.
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.
Storage conditions depend on the formulation and the intended shelf life. Many pharmaceutical and biological freeze-dried products are kept at 2–8 °C, while some stable foods and reagents tolerate room temperature. Others require −20 °C or colder to slow chemical degradation or aggregation. Protection from light and oxygen is common because oxidation can continue in the dry state. Stability studies usually monitor potency, appearance, moisture, and reconstitution time over months or years. Predictions from accelerated studies are useful but may not fully capture real-time changes.
Quality control for freeze-dried lots combines visual inspection with instrumental tests. Cake appearance, color, and shrinkage are recorded against a reference, while residual moisture is measured by Karl Fischer titration or loss on drying. Thermal analysis can reveal phase transitions and crystallization events, and X-ray diffraction distinguishes amorphous from crystalline solids. Microbiological tests and container closure integrity checks are also routine for sterile products. Analytical methods must be validated for the matrix, because excipients and low moisture can affect accuracy. Open questions include how best to predict long-term stability from short-term data.
Lyophilized solids are often hygroscopic, so handling occurs in controlled low-humidity areas or glove boxes when the material is exposed. Vials remain sealed with elastomeric stoppers and aluminum crimps until use, because airborne moisture can raise residual water and shorten shelf life. The porous cake is fragile and may crack, shrink, or powder during transport. Personnel typically avoid repeated warming and cooling of sealed units, which can draw moisture through closures. These practices aim to preserve the low water content achieved during drying.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
There are production and distribution bottlenecks, plan failures, consumer scarcities, criminal abuses of power, suppression of dissidents, and expressions of alienation among some of the population." Parenti further argued that the economies of Eastern European countries and the Soviet Union suffered from "fatal distortions in their development" because of "embargo[s], invasion, devastating wars, and costly arms buildup; excessive bureaucratization and poor incentive systems; lack of administrative initiative and technological innovation; and a repressive political rule that allowed little critical expression and feedback while fostering stagnation and elitism." In Western Europe, communist parties, which were still committed to Marxism–Leninism through more democratic means, were part of the initial post-war governments, and even when the Cold War forced many of those countries to remove them from government, such as in Italy, they remained part of the liberal-democratic process. By the 1960s and 1970s, many Western Marxist–Leninists had criticised many of the actions of Communist states, distanced from them, and developed a democratic road to socialism, which became known as Eurocommunism. This development was criticised by both non-Marxist–Leninists and other Marxist–Leninists in the East as amounting to social democracy.
== Proteolytic processing == Catechol oxidase is nuclear-encoded, and its N-terminal end contains a signal peptide that directs the protein to the chloroplast thylakoid lumen, where it can either be soluble or loosely associated with the thylakoid membrane. Initially transcribed as a pro-enzyme, the catechol oxidase precursor undergoes two rounds of proteolytic processing and transport before it enters the thylakoid lumen. Utilizing a [35S] methionine-labeled precursor protein, Sommer et al. elucidated a proteolytic processing pathway common to a variety of plants including pea (Pisum sativum), tomato (Lycopersicon esculentum), and maize (Zea mays). The 67 kD precursor was imported into the stroma in an ATP-dependent manner where a stromal peptidase processes the precursor into a 62 kD intermediate. The translocation of this intermediate into the thylakoid lumen was light-dependent and results in the generation of the mature 59 kD enzyme. Based on analysis of the precursor and mature catechol oxidase purified from Ipomoea batatas, proteolytic processing removes both the N-terminal transit peptide as well as a C-terminal domain that covers the enzyme active site.
The Marxist–Leninist worldview is atheist, wherein all human activity results from human volition and not the will of supernatural beings (gods, goddesses and demons) who have direct agency in the public and private affairs of human society. The tenets of the Soviet Union's national policy of Marxist–Leninist atheism originated from the philosophies of Georg Wilhelm Friedrich Hegel (1770–1831) and Ludwig Feuerbach (1804–1872) as well as that of Karl Marx (1818–1883) and Vladimir Lenin (1870–1924). As a basis of Marxism–Leninism, the philosophy of materialism (the physical universe exists independently of human consciousness) is applied as dialectical materialism (considered by its proponents a philosophy of science, history and nature) to examine the socio-economic relations among people and things as parts of a dynamic, material world that is unlike the immaterial world of metaphysics. Soviet astrophysicist Vitaly Ginzburg said that ideologically the "Bolshevik communists were not merely atheists, but, according to Lenin's terminology, militant atheists" in excluding religion from the social mainstream, from education and from government.
== Protein structure == Galactose oxidase contains 639 amino acids. It is a single peptide monomer that has three β-structural domains. Domain 1 (residues 1-155) is a β-sandwich consisting of eight antiparallel β-strands. It contains a possible binding site for Na+ or Ca2+, which may serve structural roles in the protein. Another feature of Domain 1 is the presence of a carbohydrate binding site that direct the enzyme to bind to extracellular carbohydrates. Domain 2 (residues 156-552) contains the copper binding site. The β-strands in Domain 2 are organized as a seven-fold propeller, and each of the seven structural units is a subdomain consisting of four antiparallel β-strands. Domain 3 (residues 553-639) consists of seven anti-parallel β-strands and forms a “cap” over Domain 2. One histidine (His581) of Domain 3 serves as the ligand for copper, contributing to the metal-containing active site of the enzyme.
Silicon (Si) is the second most common element in the Earth's crust after oxygen. The compound silica, also known as silicon dioxide (SiO2), is formed from silicon and oxygen atoms. Since oxygen and silicon make up about 75% of the Earth's crust, the compound silica is quite common. It is found in many rocks, such as granite, sandstone, gneiss and slate, and in some metallic ores. Silica can be a main component of sand. It can also be in soil, mortar, plaster, and shingles. The cutting, breaking, crushing, drilling, grinding, or abrasive blasting of these materials may produce fine to ultra-fine airborne silica dust. Silica occurs in three forms: crystalline, microcrystalline (or cryptocrystalline) and amorphous (non-crystalline). "Free" silica is composed of pure silicon dioxide, not combined with other elements, whereas silicates (e.g., talc, asbestos, and mica) are SiO2 combined with an appreciable portion of cations.
Sources: en.wikipedia.org
== SU == su – (s) Sundanese language (ISO 639-1 code) SU (s) Soviet Union (ISO 3166 digram; obsolete 1992) Sudan (FIPS 10-4 country code) SUB – (i) Student Union Building SuD – (a) Subject under Discussion SUDC – Swedish United Dawah Center, a salafist Islamic organisation in Sweden SUI (a) Sonic user interface (s) Switzerland (IOC and FIFA trigram, but not ISO 3166) SUK – Start Up Kit sun – (s) Sundanese language (ISO 639-2 code) SUN – (s) Soviet Union (ISO 3166 trigram; obsolete 1992) Stanford University Network that led to Sun Microsystems SUNY – (a) State University of New York (usually pronounced "sue-knee") SUR – (s) Suriname (ISO 3166 trigram) SURTASS – (p) Surveillance Towed Array Sensor System SUSAT – (a) Sight Unit Small Arms, Trilux SUV – (i) Sport Utility Vehicle
Denys performed another transfusion into a labourer, who also survived. Both instances were likely due to the small amount of blood that was actually transfused into these people. This allowed them to withstand the allergic reaction. Denys's third patient to undergo a blood transfusion was Swedish Baron Gustaf Bonde. He received two transfusions. After the second transfusion Bonde died. In the winter of 1667, Denys performed several transfusions on Antoine Mauroy with calf's blood. On the third account Mauroy died. Six months later in London, Lower performed the first human transfusion of animal blood in Britain, where he "superintended the introduction in [a patient's] arm at various times of some ounces of sheep's blood at a meeting of the Royal Society, and without any inconvenience to him." The recipient was Arthur Coga, "the subject of a harmless form of insanity." Sheep's blood was used because of speculation about the value of blood exchange between species; it had been suggested that blood from a gentle lamb might quiet the tempestuous spirit of an agitated person and that the shy might be made outgoing by blood from more sociable creatures. Coga received 20 shillings (equivalent to £206 in 2025) to participate in the experiment. Lower went on to pioneer new devices for the precise control of blood flow and the transfusion of blood; his designs were substantially the same as modern syringes and catheters. Shortly after, Lower moved to London, where his growing practice soon led him to abandon research.
=== Treatment === Early administration (within 2–6 hours of bite) of antivenom and intubation for respiratory paralysis are keystones of management, but a chance of a hypersensivity reaction exists following antivenom administration. Neurotoxic symptoms may be irreversible once established due to the presynaptic nature of their pathology. The first taipan-specific antivenom was developed in 1954. Before this, tiger snake antivenom was used, though it was of little benefit in taipan envenomation.
The fish is beheaded, eviscerated and cut flat by removing the spine, often on board the boat or ship (this is feasible with whitefish, whereas it would not be with oily fish). It is then salted and dried ashore. Traditionally the fish was sun-dried on rocks or wooden frames, but modern commercial production is mainly dried indoors with electrical heating. It is sold whole or in portions, with or without bones.
== Pathophysiology == Since envenomation is completely voluntary, all venomous snakes are capable of biting without injecting venom into a person. Snakes may deliver such a "dry bite" rather than waste their venom on a creature too large for them to eat, a behaviour called venom metering. However, the percentage of dry bites varies among species: 80 percent of bites inflicted by sea snakes, which are normally timid, do not result in envenomation, whereas for pit viper bites the number is closer to 25 percent. Furthermore, some snake genera, such as rattlesnakes, can internally regulate the amount of venom they inject. There is a wide variance in the composition of venoms from one species of venomous snake to another. Some venoms may have their greatest effect on a victim's respiration or circulatory system. Others may damage or destroy tissues. This variance has imparted to the venom of each species a distinct chemistry. Sometimes antivenins have to be developed for individual species. For this reason, standard therapeutic measures will not work in all cases. Some dry bites may also be the result of imprecise timing on the snake's part, as venom may be prematurely released before the fangs have penetrated the person. Even without venom, some snakes, particularly large constrictors such as those belonging to the Boidae and Pythonidae families, can deliver damaging bites; large specimens often cause severe lacerations, or the snake itself pulls away, causing the flesh to be torn by the needle-sharp recurved teeth embedded in the person.
Sources: en.wikipedia.org
The Gaza Strip, now a part of the State of Palestine, has previously been under Ottoman, British, and Egyptian control. Israel directly occupied the entirety of Gaza from 1967 to 1993, when the Palestinian Authority assumed civil control of most of the region. In 2005, Israel disengaged from the Gaza Strip, the same year the militant group Hamas won parliamentary elections in the region. Decades-long US diplomacy on Israel and the Palestinians have not produced successful resolutions in the conflict. The Gaza Strip has seen a major scale of destruction since the beginning of the Gaza war in October 2023. Civilians who were internally displaced have been able to return to their homes since the ceasefire which began on 15 January 2025. The cost of rebuilding Gaza has been estimated to be in the tens of billions of dollars. Calls to displace Palestinians from Gaza mirror demands made by those in the Israeli far-right who have often called for ethnically cleansing Palestinian land to open it up to foreign settlement.
Iron uptake is tightly regulated by the human body, which has no regulated physiological means of excreting iron. Only small amounts of iron are lost daily due to mucosal and skin epithelial cell sloughing, so control of iron levels is primarily accomplished by regulating uptake. Regulation of iron uptake is impaired in some people as a result of a genetic defect that maps to the HLA-H gene region on chromosome 6 and leads to abnormally low levels of hepcidin, a key regulator of the entry of iron into the circulatory system in mammals. In these people, excessive iron intake can result in iron overload disorders, known medically as hemochromatosis. Many people have an undiagnosed genetic susceptibility to iron overload, and are not aware of a family history of the problem. For this reason, people should not take iron supplements unless they suffer from iron deficiency and have consulted a doctor. Hemochromatosis is estimated to be the cause of 0.3–0.8% of all metabolic diseases of Caucasians. Overdoses of ingested iron can cause excessive levels of free iron in the blood. High blood levels of free ferrous iron react with peroxides to produce highly reactive free radicals that can damage DNA, proteins, lipids, and other cellular components. Iron toxicity occurs when the cell contains free iron, which generally occurs when iron levels exceed the availability of transferrin to bind the iron. Damage to the cells of the gastrointestinal tract can also prevent them from regulating iron absorption, leading to further increases in blood levels.
Eliminate the streptococcus – a course of penicillin is usually given at diagnosis to definitively clear any remaining streptococci (and avoid spread of a rheumatogenic clone), but there is no evidence that it makes any difference to the course of the illness. Treat the movement disorder Immunosuppression Prevention of relapses and further cardiac damage Manage the disability - Occupational therapy and physiotherapy are useful for maintaining function and muscle tone.
Helianthus tuberosus – Plants for a Future database Jerusalem artichoke – Ohio Perennial & Biennial Weed Guide NutritionData, Complete nutritional info. Purdue University Alternative Field Crops Manual: Jerusalem Artichoke
A number of Eastern European countries (notably without Poland) were covered by Stalin's secret agreement with Winston Churchill concluded at the 4th Moscow Conference in 1944 and called the Percentages Agreement. This only became known about in 1953 when Churchill published his memoirs. Resis' research illustrates that Roosevelt was well aware of this agreement but only gave conditional support to Churchill after receiving updated information regarding the talks; however, prior to the meeting Roosevelt had informed Stalin that "in this global war, there is no question, political or military, that the United States is not interested" and as such, the 4th October 1944 is arguably the day the Cold War started. The immediate post-1945 period may have been the historical high point for the popularity of communist ideology. The burdens the Red Army and the Soviet Union endured had earned it massive respect which, had it been fully exploited by Joseph Stalin, had a good chance of resulting in a communist Europe. Communist parties achieved a significant popularity in Greece, France and Italy, as well as in some nations outside of Europe such as China, Iran or the Republic of Mahabad. Communist parties had already come to power in Romania, Bulgaria, Albania, and Yugoslavia. The United Kingdom and the United States were concerned that electoral victories by communist parties in any of these countries could lead to sweeping economic and political change in Western Europe.
Sources: en.wikipedia.org
No. Freeze-drying removes water but does not reliably kill microorganisms. Sterile lyophilized products are typically prepared aseptically before freezing or are sterilized by a validated method. Microbial control depends on the entire manufacturing process.
Storage temperature is set by the least stable component in the formulation. Proteins, vaccines, and some small molecules can degrade faster at higher temperatures. Refrigeration slows these changes but does not stop them completely.
Collapse occurs when the product exceeds its collapse or glass transition temperature during drying. The ice structure then loses support, and the cake may shrink, melt back, or become dense. Formulation and cycle adjustments are used to keep the product below that threshold.
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.