Primary drying 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.
Updated 2026-05-08. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
| Property | Value | Notes |
|---|---|---|
| Appearance | Porous solid cake | Typically white to off-white; varies with formulation |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity and solute |
| Residual moisture | 0.5-3% w/w | Measured by Karl Fischer titration |
| Storage temperature | Room temperature to -20 °C | Product-specific; humidity-controlled |
| Common quality attribute | Cake elegance | Visual check for collapse, shrinkage, or meltback |
Analytical methods for lyophilized materials include X-ray diffraction for crystallinity, differential scanning calorimetry for thermal transitions, and scanning electron microscopy for pore morphology. Moisture sorption analysis shows how the cake responds to humidity. These methods help distinguish amorphous from crystalline states and detect phase changes. Open questions remain about how pore structure changes during long-term storage and how best to predict collapse under varied conditions. Comparisons across studies are complicated by differences in formulation, cycle, and storage history.
Quality control for lyophilized products focuses on appearance, moisture level, reconstitution time, and structural integrity. A cake should be uniform, intact, and free of meltback or collapse. Moisture level is measured by Karl Fischer titration or thermogravimetric analysis. Reconstitution time reflects pore structure and formulation. Visual inspection and vial integrity checks detect cracks, stopper defects, or particulate matter. These checks are often performed on samples from each batch. They help confirm that the drying cycle performed as intended.
Storage stability depends on water content, oxygen exposure, and temperature. Lyophilized solids are hygroscopic and can absorb water if exposed to humid air. Vials are usually sealed under vacuum or inert gas with rubber stoppers and aluminum crimps. Storage temperatures range from room temperature to refrigerated or frozen conditions depending on the material. Stability studies track potency, moisture, and physical form over time. Accelerated conditions can reveal sensitivity but may not predict long-term behavior.
A typical cycle begins with freezing, which fixes the material into a solid and determines ice crystal size. Primary drying then raises heat under vacuum so ice sublimes, often near or below the collapse temperature of the formulation. Secondary drying removes bound water that remains after ice is gone, usually by gently warming the product. Each stage balances heat input against pressure to avoid melting or structural damage. Temperature probes and pressure sensors guide the transition between stages.
In practice, lyophilization is slower and more energy intensive than simple drying. Cycle times can range from hours to several days depending on load, container, and formulation. Amorphous materials may require excipients that help preserve structure during freezing and drying. The method is widely used for biological materials, pharmaceuticals, and foods where heat drying would cause unacceptable change. Open questions remain about scaling cycles between laboratory and production equipment, and this gap affects technology transfer.
Lyophilization removes water by freezing a material and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intermediate liquid state. Because the material remains frozen during primary drying, the structure often stays porous. This porous matrix can rehydrate quickly when water is added back. The low pressure also allows vapor to leave the solid matrix without boiling.
After lyophilization, the product is usually a porous cake or powder with a large internal surface area. This structure can absorb moisture quickly if exposed to humid air, so vials are sealed under vacuum or an inert gas. Moisture uptake may lower the glass transition temperature of the dried matrix and accelerate chemical or physical degradation. Storage conditions therefore depend on the formulation, container, and intended shelf life. Some products remain stable at room temperature, while others require refrigeration or freezing.
Quality control for lyophilized products includes appearance, cake structure, reconstitution time, pH, residual moisture, and potency. Residual moisture is a key attribute because excess water can reduce stability, while excessively low moisture may cause structural changes or aggregation in some systems. Stability studies compare real-time and accelerated conditions to estimate shelf life. Analytical methods must be validated for the specific matrix, container, and moisture range. Sterility and container integrity are also monitored for sterile products.
== Encoded split and pool synthesis == Although in the S&P synthesis a single compound forms on each bead its structure is not known. For this reason, encoding methods had been introduced to help to determine the identity of the compound contained in a selected bead. Encoding molecules are coupled to the beads in parallel with the coupling of the BBs. The structure of the encoding molecule has to be easier determined than that of the library member on the bead. Ohlmeyer et al. published a binary encoding method. They used mixtures of 18 tagging molecules that after cleaving them from the beads could be identified by Electron Capture Gas Chromatography. Nikolajev et al. applied peptide sequences for encoding Sarkar et al. described chiral oligomers of pentenoic amides (COPAs) that can be used to construct mass encoded OBOC libraries. Kerr et al. introduced an innovative kind of encoding. An orthogonally protected removable bifunctional linker was attached to the beads. One end of the linker was used to attach the non-natural BBs of the library while to the other end the encoding amino acid triplets were linked. One of the earliest and very successful encoding methods was introduced by Brenner and Lerner in 1992. They proposed to attach DNA oligomers to the beads for encoding their content. The method was implemented by Nielsen, Brenner, and Janda using the bifunctional linker of Kerr et al. to attach the encoding DNA oligomers. This made it possible to cleave down the compound with the DNA encoding oligomer attached to it.
Periungual angiofibromas are also termed Koenen's tumors, periungual fibromas, and subungual fibromas. In addition, these tumors were formerly regarded as a type of acral angiofibroma (see below description). These lesions present as multiple nodules or tumors under multiple finger and/or toe nails of individuals with tuberous sclerosis or in one case the Birt-Hogg-Dube syndrome. Periungual angiofibromas have also been reported to occur in individuals that do not have these genetic diseases. Periungual angiofibromas tumors can be highly mutilating finger/toe-nail lesions.
=== Impulsive aggression === Fluoxetine is considered a first-line medication for the treatment of impulsive aggression of low intensity. Fluoxetine reduced low-intensity aggressive behavior in patients in intermittent explosive disorder and borderline personality disorder. Fluoxetine also reduced acts of domestic violence in alcoholics with a history of such behavior.
=== World War II === With the outbreak of World War II, weaponization of botulinum toxin was investigated at Fort Detrick in Maryland. Carl Lamanna and James Duff developed the concentration and crystallization techniques that Edward J. Schantz used to create the first clinical product. When the Army's Chemical Corps was disbanded, Schantz moved to the Food Research Institute in Wisconsin, where he manufactured toxin for experimental use and provided it to the academic community. The mechanism of botulinum toxin action – blocking the release of the neurotransmitter acetylcholine from nerve endings – was elucidated in the mid-20th century, and remains an important research topic. Nearly all toxin treatments are based on this effect in various body tissues.
== Statistics == The following table of executions was compiled by Amnesty International from several sources, including statistics supplied by the Ministry of Home Affairs in January 2001 and government figures reported to Agence France-Presse in September 2003. Numbers in curly brackets are the number of foreign citizens executed, according to information disclosed by the Ministry of Home Affairs.
Sources: en.wikipedia.org
An exudate is a fluid released by an organism through pores or a wound, a process known as exuding or exudation. Exudate is derived from exude 'to ooze' from Latin exsūdāre 'to (ooze out) sweat' (ex- 'out' and sūdāre 'to sweat').
In vitro, VPg-RNA conjugates were translated with similar efficiency to m7G-capped RNAs indicating that VPg binds eIF4E and engages the translation machinery; while free VPg (in the absence of conjugated RNA) successfully competes for all the cap-dependent activities of eIF4E in the cell inhibiting translation and RNA export.
== Labor conditions and diet == Some groups, such as PETA, promote vegetarianism as a way to offset poor treatment and working conditions of workers in the contemporary meat industry. These groups cite studies showing the psychological damage caused by working in the meat industry, especially in factory and industrialised settings, and argue that the meat industry violates its labourers' human rights by assigning difficult and distressing tasks without adequate counselling, training and debriefing. However, the working conditions of agricultural workers as a whole, particularly non-permanent workers, remain poor and well below conditions prevailing in other economic sectors. Accidents, including pesticide poisoning, among farmers and plantation workers contribute to increased health risks, including increased mortality. According to the International Labour Organization, agriculture is one of the three most dangerous jobs in the world.
The Ingram family's steadfast refusal to franchise, take on debt or offer shares to the public throughout the company's existence has kept the chain relatively small, with a more discontinuous geography than its principal competitors. There are currently 345 White Castle outlets, as of May 17, 2024, predominantly in the Midwest, Kentucky, and Tennessee. The exceptions are over 50 White Castle locations in the New York—New Jersey metropolitan area (as of 2025), four locations around Las Vegas, Nevada, four in the Phoenix metropolitan area in Arizona, one in Orlando, Florida, and two in Shanghai, China. By comparison, there are over 36,000 McDonald's locations globally, with approximately 14,000 of those in the United States. The chain does, however, sell frozen sliders at supermarkets nationwide, with availability varying by chain. White Castle currently has locations in the following metropolitan areas in the United States:
Endocrinology is a branch of internal medicine dealing with hormones, the chemical messengers released internally to regulate the body's physiologic functions. Endocrinologists diagnose and manage diseases of endocrine glands, including hypothalamus, pituitary, thyroid, parathyroid, pancreatic islets, adrenals, testes, and ovaries. Some of the most common conditions treated are diabetes mellitus, diseases of the thyroid gland, metabolic bone disorders, pituitary disorders, and disorders of the reproductive system and infertility; in children, typical conditions are growth deficiency, delay of puberty, and a variety of genetic disorders. In endocrinology, diagnosis is heavily relied on laboratory tests, as it is important to find out diseases before they actually become clinically evident; still, medical history and physical examination remain indispensable. As a branch of internal medicine, practice of endocrinology makes use of common medical instruments, used by all or most clinical specialties, like the stethoscope or the sphygmomanometer. The following list does not include these, but only instruments that have relatively specific uses central to endocrinology (but not necessarily limited to it). They are either utilized by the physician (generally the endocrinologist themselves, or potentially by a different specialist, like a radiologist) for diagnosis or treatment; or prescribed for patient use.
Sources: en.wikipedia.org
The first published recommendations for protection against radium and radiation in general were made by the British X-ray and Radium Protection Committee and were adopted internationally in 1928 at the first meeting of the International Commission on Radiological Protection (ICRP), following preliminary guidance written by the Röntgen Society. This meeting led to further developments of radiation protection programs coordinated across all countries represented by the commission. Exposure to radium is still regulated internationally by the ICRP, alongside the World Health Organization. The International Atomic Energy Agency (IAEA) publishes safety standards and provides recommendations for the handling of and exposure to radium in its works on naturally occurring radioactive materials and the broader International Basic Safety Standards, which are not enforced by the IAEA but are available for adoption by members of the organization. In addition, in efforts to reduce the quantity of old radiotherapy devices that contain radium, the IAEA has worked since 2022 to manage and recycle disused 226Ra sources. In several countries, further regulations exist and are applied beyond those recommended by the IAEA and ICRP. For example, in the United States, the Environmental Protection Agency-defined Maximum Contaminant Level for radium is 5 pCi/L for drinking water; at the time of the Manhattan Project in the 1940s, the "tolerance level" for workers was set at 0.1 micrograms of ingested radium.
Zopiclone is used for the short-term treatment of insomnia where difficulty with sleep initiation or sleep maintenance are prominent symptoms. Long-term use is not recommended, as tolerance, dependence, and addiction can occur. Benzodiazepine-like drugs decrease sleep latency by 10 to 20 minutes. However, no benzodiazepine-like drug has shown clinically significant increase in total sleep time which is defined as at least 30 minutes. Tolerance develops within days to weeks. The risk of developing tolerance with benzodiazepine-like drugs is comparable to benzodiazepines. Zopiclone is recommended to be taken at the lowest effective dose, with a duration of 2–3 weeks for short-term insomnia. Use of zopiclone more than 4 weeks is not recommended. Caution must be taken when the compound is used in conjunction with benzodiazepines, sedatives or other drugs affecting the central nervous system. One low-quality study found that zopiclone is ineffective in improving sleep quality or increasing sleep time in shift workers. Cognitive behavioral therapy has been found to be superior to zopiclone in the treatment of insomnia and has been found to have lasting effects on sleep quality for at least a year after therapy.
Birds and bats have homologous limbs because they are both ultimately derived from terrestrial tetrapods, but their flight mechanisms are only analogous, so their wings are examples of functional convergence. The two groups have independently evolved their own means of powered flight. Their wings differ substantially in construction. The bat wing is a membrane stretched across four extremely elongated fingers and the legs. The airfoil of the bird wing is made of feathers, strongly attached to the forearm (the ulna) and the highly fused bones of the wrist and hand (the carpometacarpus), with only tiny remnants of two fingers remaining, each anchoring a single feather. So, while the wings of bats and birds are functionally convergent, they are not anatomically convergent. Birds and bats also share a high concentration of cerebrosides in the skin of their wings. This improves skin flexibility, a trait useful for flying animals; other mammals have a far lower concentration. The extinct pterosaurs independently evolved wings from their fore- and hindlimbs, while insects have wings that evolved separately from different organs. Flying squirrels and sugar gliders are much alike in their mammalian body plans, with gliding wings stretched between their limbs, but flying squirrels are placentals while sugar gliders are marsupials, widely separated within the mammal lineage from the placentals. Hummingbird hawk-moths and hummingbirds have evolved similar flight and feeding patterns.
== Professional affiliations == Beavis was a founding member of Genome Prairie and one of the founders of ProteoMetrics, LLC. He has held academic positions at Rockefeller University, Memorial University of Newfoundland and Labrador, New York University Medical Center, the University of British Columbia and the University of Manitoba. He served on the Editorial Advisory Boards of the Journal of Proteome Research and Rapid Communications in Mass Spectrometry. He has also served on the Editorial Board of Molecular & Cellular Proteomics and on the Editorial Board of Scientific Data. He was part of the Human Proteome Project and a founding member of the U.S. Chromosome 17 project. He has frequently collaborated with David Fenyő on informatics projects.
Sources: en.wikipedia.org
Karl Fischer titration is a common reference method that quantifies water by a chemical reaction. Thermogravimetric analysis can also estimate moisture by weight loss on heating. Method choice depends on sample size and whether other volatile substances are present.
Cake collapse often occurs when the product exceeds its collapse temperature during primary drying. The frozen matrix loses structure and the ice channels close. Optimizing formulation and cycle parameters helps avoid this defect.
No. Storage temperature depends on the stability of the dried material. Some products are stable at room temperature, while others require refrigeration or freezing. Container integrity and moisture barriers also affect shelf life.
Yes. Lyophilization and freeze-drying are synonyms for the same vacuum-assisted sublimation process. The term lyophilization is more common in pharmaceutical and laboratory settings, while freeze-drying is widely used in food and general contexts.