Eutectic temperature raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-12-25. Anything still debated is marked as such rather than presented as settled.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
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.
| Property | Value | Notes |
|---|---|---|
| Process name | Lyophilization or freeze-drying | Both terms appear in technical standards and literature. |
| Phase transition | Sublimation | Solid ice becomes vapor without a liquid step. |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product temperature and equipment. |
| Typical product temperature | -40 °C to -10 °C | Measured during primary drying; formulation sets limits. |
| Water content after drying | 0.5-3% w/w | Target varies by material and stability needs. |
== Procedure == The process for TLC is similar to paper chromatography but provides faster runs, better separations, and the choice between different stationary phases. Plates can be labelled before or after the chromatography process with a pencil or other implement that will not interfere with the process. There are four main stages to running a thin-layer chromatography plate: Plate preparation: Using a capillary tube, a small amount of a concentrated solution of the sample is deposited near the bottom edge of a TLC plate. The solvent is allowed to evaporate before the next step completely. A vacuum chamber may be necessary for non-volatile solvents. The spotting procedure can be repeated to ensure sufficient compound to obtain a visible result. Depending on the application, multiple samples may be placed in a row, the same distance from the bottom edge; each sample will move up the plate in its own "lane."
The body is continually exposed to many species of bacteria, including beneficial commensals, which grow on the skin and mucous membranes, and saprophytes, which grow mainly in the soil and in decaying matter. The blood and tissue fluids contain nutrients sufficient to sustain the growth of many bacteria. The body has defence mechanisms that enable it to resist microbial invasion of its tissues and give it a natural immunity or innate resistance against many microorganisms. Unlike some viruses, bacteria evolve relatively slowly so many bacterial diseases also occur in other animals. If bacteria form a parasitic association with other organisms, they are classed as pathogens. Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus (caused by Clostridium tetani), typhoid fever, diphtheria, syphilis, cholera, foodborne illness, leprosy (caused by Mycobacterium leprae) and tuberculosis (caused by Mycobacterium tuberculosis). A pathogenic cause for a known medical disease may only be discovered many years later, as was the case with Helicobacter pylori and peptic ulcer disease. Bacterial diseases are also important in agriculture, and bacteria cause leaf spot, fire blight and wilts in plants, as well as Johne's disease, mastitis, salmonella and anthrax in farm animals.
=== Polymer synthesis === SEC can be used as a measure of both the size and the polydispersity of a synthesized polymer, that is, the ability to find the distribution of the sizes of polymer molecules. If standards of a known size are run previously, then a calibration curve can be created to determine the sizes of polymer molecules of interest in the solvent chosen for analysis (often THF). In alternative fashion, techniques such as light scattering and/or viscometry can be used online with SEC to yield absolute molecular weights that do not rely on calibration with standards of known molecular weight. Due to the difference in size of two polymers with identical molecular weights, the absolute determination methods are, in general, more desirable. A typical SEC system can quickly (in about half an hour) give polymer chemists information on the size and polydispersity of the sample. The preparative SEC can be used for polymer fractionation on an analytical scale.
Stroganoff is also popular in Nordic countries. In Sweden, a common variant is Korv stroganoff (lit. 'sausage stroganoff'), which traditionally uses the local falukorv sausage as a substitute for the beef. In Finland, the dish is called makkarastroganoff (lit. 'sausage stroganoff'). Beef Stroganoff is, however, also a common dish in Finland. Diced brined pickles are also a normal ingredient in Finnish Stroganoff.
Thus, the molar mass of a substance X can be calculated as M(X) = Ar(X) ⋅ Mu, with the molar mass constant Mu equal to exactly 1 Da/ent, which (for all practical purposes) is equal to 1 g/mol, as the mole was historically defined such that the Avogadro number (the number of atomic-scale entities comprising one mole) was exactly equal to the number of daltons in a gram (g/Da). This means that (for all practical purposes): 1 mol = (g/Da) ent. The relationship between the molar mass of carbon-12, M(12C) = 12 g/mol, and its atomic mass, ma(12C) = 12 Da, can be expressed as M(12C) = ma(12C) · NA. Rearranging and substituting the given values into the equation yields the following expression for the Avogadro constant: NA = (g/Da) mol−1, making the Avogadro number equal to the number of daltons in a gram, and equivalently the number of atoms in 12 grams of carbon-12 (as in the 1971 definition of the mole). The mole was defined in such a way that the numerical value of the molar mass of a substance in g/mol, i.e. M(X)/(g/mol), was equal to the numerical value of the average mass of one entity (atom, molecule, formula unit) in Da, i.e. ma(X)/Da = Ar(X), so that M(X) = Ar(X) g/mol. The equivalence was exact before the redefinition of the mole in 2019, and is now only approximate, but equality may still be assumed with high accuracy. Thus, for example, the average mass of a molecule of water is about 18.0153 Da, and the molar mass of water is about 18.0153 g/mol.
Sources: en.wikipedia.org
== Antagonists == Growth hormone receptor antagonists such as pegvisomant (trade name Somavert) are used in the treatment of acromegaly. They are used if the tumor of the pituitary gland causing the acromegaly cannot be controlled with surgery or radiation, and the use of somatostatin analogues is unsuccessful. Pegvisomant is delivered as a powder that is mixed with sterilized water and injected under the skin.
== Synthesis == The easiest way of synthesizing PVDF is the radical polymerization of vinylidene fluoride (VF2), however, the polymerization is not completely regiospecific. The asymmetric structure of VF2 leads to the orientation isomers during the polymerization. The configuration of the monomer in the chain can be either "head to head" or "head to tail".
Katy Higginson, lately Deputy Head, Royal and Coronation Unit, Foreign, Commonwealth and Development Office. For services to British Foreign Policy, to International Development, and to the Coronation of Their Majesties The King and The Queen. Dr Andi Hoxhaj, Lecturer in Law (Assistant Professor of Law), University College London. For services to UK/Albania Relations. Professor Alan Jamieson, Director, Deep Sea Centre, University of Western Australia. For services to Marine Biology, Subsea Engineering and Exploration. Dipak Karadia, Team Leader, Foreign, Commonwealth and Development Office. For services to National Security. Haifa Al Kaylani, President and Founder, Arab International Women's Forum. For services to women, to young people, and to cultural relations between the UK and the countries of the Middle East and North Africa region. Moses Kirkconnell III, Member of Parliament for Cayman Brac West and Little Cayman, Cayman Islands. For services to the Caymanian People, to the Tourism Industry, and to District Administration in the Cayman Islands. Gabrielle Kirstein, Founder and Chief Executive Officer, Feeding Hong Kong. For services to the community and tackling food waste and food poverty in Hong Kong. Leona Lewis, Singer-Songwriter, Performer and Philanthropist. For services to Music and to Charity. Sarah Lingard, lately Head of Events, Royal and Coronation Unit, Foreign, Commonwealth and Development Office. For services to British Foreign Policy and to the Coronation of Their Majesties The King and The Queen.
Chemical pathology, also called clinical chemistry Hematopathology Blood banking - Transfusion medicine Clinical microbiology Cytogenetics Molecular genetics pathology. In some countries other sub specialities fall under certified Clinical Biologists responsibility:
Sources: en.wikipedia.org
==== Post-SSRI sexual dysfunction ==== Post-SSRI sexual dysfunction (PSSD) refers to a set of symptoms reported by some people who have taken SSRIs or other serotonin reuptake-inhibiting (SRI) drugs, in which sexual dysfunction symptoms persist for at least three months after ceasing to take the drug. The status of PSSD as a legitimate and distinct pathology is contentious; several researchers have proposed that it be recognized as a separate phenomenon from more common SSRI side effects. The reported symptoms of PSSD include reduced sexual desire or arousal, erectile dysfunction in males or loss of vaginal lubrication in females, persistent premature ejaculation (even in patients without a previous history of the condition), difficulty having an orgasm or loss of pleasurable sensation associated with orgasm, and a reduction or loss of sensitivity in the genitals or other erogenous zones. Additional non-sexual symptoms are also commonly described, including emotional numbing, anhedonia, depersonalization or derealization, and cognitive impairment. The duration of PSSD symptoms appears to vary among patients, with some cases resolving in months and others in years or decades; one analysis of patient reports submitted between 1992 and 2021 in the Netherlands listed a case which had reportedly persisted for 23 years.
Despite being raised as a communicant of the Catholic Church, on January 19, 2016, Duterte clarified that he had not attended Mass for quite some time already since he deemed it incompatible with his mayoral responsibilities: "If I listened to the Ten Commandments or to the priests," said Duterte, "I would not be able to do anything as a mayor." Duterte has described himself as Christian in 2016 and "spiritual" in 2018, expressing that he "can't accept" Catholicism or organized religion but also that he is neither an atheist nor an agnostic. He has referred to God as Allah and has been quoted as saying: "a part of me which is Islam". During his presidency, Duterte and the Catholic Church in the Philippines exchanged frequent criticisms. In response to the rising death toll in Duterte's war on drugs, the Catholic Bishops' Conference of the Philippines (CBCP) in February 2017 issued a strongly worded pastoral letter which was read in church services; the letter highlighted that "[killing] is considered as normal", and "to consent and keep silent in front of evil is to be an accomplice to it". Duterte later lambasted Catholic bishops, telling them "not use the pulpit", reviling them as "sons of bitches", remarking that some of them are gay, and urging street bums to rob and kill them. Notable among the bishops Duterte criticized was Caloocan Bishop Pablo Virgilio David, a vocal critic of the Duterte administration's war on drugs.
Bruising and bleeding can result from decreased production of blood clotting factors. Hepatic encephalopathy (HE) occurs when ammonia and related substances build up in the blood. This build-up affects brain function when they are not cleared from the blood by the liver. Symptoms can include unresponsiveness, forgetfulness, trouble concentrating, changes in sleep habits, or psychosis. One classic physical examination finding is asterixis. This is the asynchronous flapping of outstretched, dorsiflexed hands. Fetor hepaticus is a musty breath odor resulting from increased dimethyl sulfide and is a feature of HE. Increased sensitivity to medication can be caused by decreased metabolism of the active compounds. Acute kidney injury (particularly hepatorenal syndrome). Cachexia associated with muscle wasting and weakness.
== Synthesis == Fumaric acid is produced based on catalytic isomerisation of maleic acid in aqueous solutions at low pH. It precipitates from the reaction solution. Maleic acid is accessible in large volumes as a hydrolysis product of maleic anhydride, produced by catalytic oxidation of benzene or butane.
=== Randomized clinical trials === Randomized controlled trials have compared TOPS to lumbar fusion in patients with lumbar spinal stenosis and grade I degenerative spondylolisthesis. In a large multicenter trial, TOPS demonstrated significantly higher rates of clinical success compared with fusion at two years. Three-year results from the same randomized multicenter investigational device exemption study reported composite clinical success in 76.0% of patients treated with TOPS and 56.8% of patients treated with fusion.
Sources: en.wikipedia.org
Conventional drying uses heat to evaporate liquid water, often at temperatures that can degrade sensitive materials. Lyophilization freezes the material first and then removes water by sublimation under vacuum. This avoids prolonged exposure to liquid water and high heat.
Lowering pressure reduces the boiling point of water and allows ice to sublimate at temperatures below freezing. Vacuum also limits convective heat transfer, so heat is usually supplied by shelves or radiation. The pressure must stay below the vapor pressure of ice at the product temperature.
The cycle typically includes freezing, primary drying, and secondary drying. Freezing solidifies water and sets the pore structure; primary drying removes bulk ice; secondary drying removes bound water. Some cycles add annealing or pre-freezing steps.
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.