sublimation raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-07-05. Anything still debated is marked as such rather than presented as settled.
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.
Lyophilization is a dehydration technique in which a product is frozen and the solvent is removed under reduced pressure. The low pressure allows ice to sublimate directly into vapor without passing through a bulk liquid phase. This differs from conventional drying, where heat drives evaporation and can damage heat-sensitive structures. The process is used for biological materials, pharmaceutical formulations, and some foods. Its main advantage is preservation of porous structure and rapid reconstitution.
Quality control for lyophilized materials includes visual inspection, residual moisture measurement, and reconstitution testing. Cake appearance can reveal process problems such as collapse, shrinkage, or meltback, although appearance alone does not prove potency. Residual moisture is commonly measured by Karl Fischer titration or by loss on drying. Reconstitution time is checked because a slow or incomplete dissolve can indicate a change in pore structure. Stability studies track these attributes over time under defined temperature and humidity conditions.
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.
| 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 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.
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.
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.
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.
Quality control also examines cake structure, color, and reconstitution behavior. A collapsed or shrunken cake can indicate a thermal excursion during drying. Analytical methods such as X-ray diffraction, differential scanning calorimetry, and near-infrared spectroscopy can detect crystallinity or moisture distribution. Regulatory expectations focus on validated assays and lot-to-lot consistency. Questions remain about how well accelerated stability tests predict long-term behavior for every formulation. Visual inspection remains common but is subjective without trained reviewers and reference images.
After lyophilization, a product's quality depends on residual moisture, cake appearance, and reconstitution time. Residual moisture is often measured by Karl Fischer titration or thermogravimetric analysis. A low moisture content can slow chemical degradation, but overly dry cakes may be brittle or slow to dissolve. Stability studies track these attributes over months under defined temperature and humidity conditions. Batch records link these measurements to specific process runs and help identify trends before a product fails specification.
Storage conditions for dried products usually aim to exclude moisture and oxygen. Vials are sealed under vacuum or with an inert gas, and stoppers must maintain a barrier during transport. Temperature recommendations vary; some materials remain stable at room temperature, while others need refrigeration or frozen storage. Humidity control is critical because dried cakes can absorb water rapidly once a container is opened. Desiccant packs and moisture-barrier bags add further protection during shipping.
Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire- and tube-drawing machines, printing presses, cars, motorcycles, and bicycles. It consists of a series of short cylindrical rollers held together by side links. It is driven by a toothed wheel called a sprocket. It is a simple, reliable, and efficient means of power transmission. Sketches by Leonardo da Vinci in the 16th century show a chain with a roller bearing. In 1800, James Fussell patented a roller chain on development of his balance lock and in 1880 Hans Renold patented a bush roller chain.
The United States Armed Forces' Meal, Ready-to-Eat (MRE) is packaged similarly to the Canadian ration. Each sealed plastic bag contains one entire precooked meal, with a number of supplements and accessories. The original 12 menus have been expanded to 24 and now contain a variety of ethnic and special request items as well. Kosher/Halal and Vegetarian menus are also provided. Each meal bag contains an 8-ounce (230 g) main course (packaged in a four-layer plastic and foil laminate retort pouch), 8 hardtack crackers, some form of spread (cheese, peanut butter, or jelly), a fruit-based beverage powder, some form of dessert (cake, candy, cookies, or fruit), and an accessory packet containing coffee or tea, creamer, sugar, salt, matches, a plastic spoon, and toilet paper. A chemical heater is packed with every meal. The First Strike Ration (FSR) is a compact, eat-on-the-move ration to be used for no more than three days during initial periods of highly intense, highly mobile combat assaults. A single FSR (24 hours food) is about 50% of the size and weight of three MREs. Each FSR provides 2,900 kcal (12,000 kJ) (15% protein, 53% carbohydrates, 34% fat), versus the 3,800 kcal (16,000 kJ) in three MREs, and has a two-year shelf life when stored at 80 °F (27 °C).
== 1960s == Foreign complaints about South Africa's segregated sports brought more isolation. In 1960, Verwoerd barred a Māori rugby player from touring South Africa with New Zealand, and the tour was cancelled. New Zealand made a decision not to send an authorised rugby team to South Africa again. In 1961, South Africa left the Commonwealth, having been forced out at the 1961 Commonwealth Prime Ministers' Conference. In 1963, Lloyd McDermott, the first Australian aborigine on the Australia team refused to go on a tour of South Africa, and switched to rugby league as a result. B. J. Vorster took Verwoerd's place as PM in 1966 and declared that South Africa would no longer dictate to other countries what their teams should look like. Although this reopened the gate for sporting competition, it did not signal the end of South Africa's racist sporting policies. In 1968, Vorster went against his policy by refusing to permit Basil D'Oliveira, a Coloured South African-born cricketer, to join the English cricket team on its tour to South Africa. Vorster said that the side had been chosen only to prove a point, and not on merit. After protests, however, "Dolly" was eventually included in the team. Protests against certain tours brought about the cancellation of a number of other visits, like that of an England rugby team in 1969/70.
sequence logo In bioinformatics, a graphical representation of the conservation of nucleobases or amino acids at each position within a nucleic acid or protein sequence. Sequence logos are created by aligning many sequences and used to depict consensus sequences as well as the degree of variability within the pool of aligned sequences.
Sources: en.wikipedia.org
One person was killed in a Russian attack in Kherson. Ukraine established a national registry to document sexual violence by Russian forces in the country. North Korean dictator Kim Jong Un pledged to “unconditionally support” Russia with its invasion of Ukraine during a visit by Putin to Pyongyang. Russian opposition media claimed that, during 2024, Russian aircraft accidentally dropped 103 bombs on Russian soil and Russian occupied territories.
After secondary (10+), education is called DMLT; it is two years offered by vocational boards of respective states. After post-secondary education (12+), it is also called the DMLT of two years offered by vocational boards of respective states. The undergraduate degree in MLT is three or four years offered by universities. State boards of technical education (i.e., MSBTE) offer an Advanced Diploma of two years equivalent to the PGDMLT (postgraduate diploma in medical laboratory technology) offered by universities. A postgraduate degree in MLS is two years offered by universities.
To avoid epimerization through the O-acylisourea intermediate formed when using a carbodiimide reagent, an amidinium- or phosphonium-reagent can be employed These reagents have two parts: an electrophilic moiety which deoxygenates the carboxylic acid (blue) and masked nucleophilic moiety (red). Nucleophilic attack of the carboxylic acid on the electrophilic amidinium or phosphonium moiety leads to a short lived intermediate which is rapidly trapped by the unmasked nucleophile to form the activated ester intermediate and either a urea or phosphoramide by-product. These cationic reagents have non-coordinating counteranions such as a hexafluorophosphate or a tetrafluoroborate. The identity of this anion is typically indicated by the first letter in the reagent's acronym, although the nomenclature can be inconsistent. For example HBTU is a hexafluorophosphate salt while TBTU is a tetrafluoroborate salt. In addition to HBTU and HATU other common reagents include HCTU (6-ClHOBt), TCFH (chloride) and COMU (ethyl cyano(hydroxyimino)acetate). Amidinium reagents incorporating hydroxybenzotriazole moieties can exist in an N-form (guanadinium) or an O-form (uronium), but the N-form is generally more stable. Phosphonium reagents include BOP (HOBt), PyBOP (HOBt) and PyAOP (HOAt). Although these reagents can lead to the same activated ester intermediates as a carbodiimide reagent, the rate of activation is higher due to the high electrophilicity of these cationic reagents.
Beginning in the 1960s, there was renewed interest in Tyrannosaurus, resulting in the recovery of 42 skeletons (5–80% complete by bone count) from western North America. In 1967, Dr. William MacMannis located and recovered the skeleton named "MOR 008", which is 15% complete by bone count and has a reconstructed skull displayed at the Museum of the Rockies. The 1990s saw numerous discoveries, with nearly twice as many finds as in all previous years, including two of the most complete skeletons found to date: Sue and Stan. Sue Hendrickson discovered the most complete (approximately 85%) and largest Tyrannosaurus skeleton in the Hell Creek Formation on August 12, 1990. The specimen Sue, named after the discoverer, was the object of a legal battle over its ownership. In 1997, the litigation was settled in favor of Maurice Williams, the original land owner. The fossil collection was purchased by the Field Museum of Natural History at auction for $7.6 million, making it the most expensive dinosaur skeleton until the sale of Stan for $31.8 million in 2020. The mounted skeleton opened to the public on May 17, 2000. A study of this specimen's fossilized bones showed that Sue reached full size at age 19 and died at the age of 28, the longest estimated life of any tyrannosaur known.
TIM is the protein transport machinery of the mitochondrial inner membrane that contains three essential TIM proteins: Tim17 and Tim23 are thought to build a preprotein translocation channel while Tim44 interacts transiently with the matrix heat-shock protein Hsp70 to form an ATP-driven import motor. ATP + H2O + mitochondrial protein [side 1] = ADP + phosphate + mitochondrial protein [side 2] 7.4.2.4 ABC-type chloroplast protein-transporting ATPase The enzyme appears in viruses and cellular organisms. Involved in the transport of proteins or preproteins into chloroplast stroma (several ATPases may participate in this process). ATP + H2O + chloroplast protein [side 1] = ADP + phosphate + chloroplast protein [side 2] 7.4.2.5 ABC-type protein transporter The expected taxonomic range for this enzyme is: Eukaryota, Bacteria. This entry stands for a family of bacterial enzymes that are dedicated to the secretion of one or several closely related proteins belonging to the toxin, protease and lipase families. Examples from Gram-negative bacteria include α-hemolysin, cyclolysin, colicin V and siderophores, while examples from Gram-positive bacteria include bacteriocin, subtilin, competence factor and pediocin. ATP + H2O + protein [side 1] = ADP + phosphate + protein [side 2] 7.4.2.6 ABC-type oligopeptide transporter A bacterial enzyme that interacts with an extracytoplasmic substrate binding protein and mediates the import of oligopeptides of varying nature. The binding protein determines the specificity of the system. Does not undergo phosphorylation during the transport process.
Sources: en.wikipedia.org
Hosokawa Micron Powder Systems is an American company located in Summit, New Jersey, which designs and manufactures equipment for size reduction, classification and mixing of chemical, pharmaceutical and food materials. The company was started in 1923 by Louis Ruprecht named Pulverizing Company and was later bought by the Hosokawa Micron Group in 1985.
== Capital crimes == In addition to the Penal Code, there are four Acts of Parliament that prescribe death as punishment for offences. According to the Think Centre, a Singaporean civil rights group, 70% of hangings are for drug-related offences. All eight hangings in 2017 were for drug-related offences that year, and 11 of 13 hangings in 2018 were also for drug-related offences.
==== Analysis ==== Analysis of FISH specimens is done by fluorescence microscopy by a clinical laboratory specialist in cytogenetics. For oncology, generally, a large number of interphase cells are scored in order to rule out low-level residual disease, generally between 200 and 1,000 cells are counted and scored. For congenital problems usually 20 metaphase cells are scored.
=== Nervous system === People with amyloidosis may have central nervous system involvement, along with peripheral involvement which causes sensory and autonomic neuropathies. Sensory neuropathy develops in a symmetrical pattern and progresses in a distal to proximal manner. Autonomic neuropathy can present as orthostatic hypotension but may manifest more gradually with nonspecific gastrointestinal symptoms like constipation, nausea, or early satiety. Amyloidosis of the central nervous system can have more severe and systemic presentations that may include life-threatening arrhythmias, cardiac failure, malnutrition, infection, or death. Neuropathic presentation can depend on the etiology of amyloidosis. People with amyloidosis may experience dysfunction in various organ systems depending on the location and extent of nervous system involvement. For example, peripheral neuropathy can cause erectile dysfunction, incontinence and constipation, pupillary dysfunction, and sensory loss depending on the distribution of amyloidosis along different peripheral nerves.
The direct gating or opening of the chloride ion channel is the reason for the increased toxicity of barbiturates compared to benzodiazepines in overdose. Further, barbiturates are relatively non-selective compounds that bind to an entire superfamily of ligand-gated ion channels, of which the GABAA receptor channel is only one of several representatives. This Cys-loop receptor superfamily of ion channels includes the neuronal nACh receptor channel, the 5-HT3 receptor channel, and the glycine receptor channel. However, while GABAA receptor currents are increased by barbiturates (and other general anesthetics), ligand-gated ion channels that are predominantly permeable for cationic ions are blocked by these compounds. For example, neuronal nAChR channels are blocked by clinically relevant anesthetic concentrations of both thiopental and pentobarbital. Such findings implicate (non-GABA-ergic) ligand-gated ion channels, e.g. the neuronal nAChR channel, in mediating some of the (side) effects of barbiturates. This is the mechanism responsible for the (mild to moderate) anesthetic effect of barbiturates in high doses when used in anesthetic concentration.
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.
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.