This is a working overview of secondary drying, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-01. Anything still debated is marked as such rather than presented as settled.
Quality control for lyophilized materials includes visual inspection of the cake, measurement of residual moisture, and tests for reconstitution time. An acceptable cake is typically uniform and may be slightly porous; shrinkage, meltback, or cracks can indicate process deviations. Analytical methods such as Karl Fischer titration, thermogravimetric analysis, and near-infrared spectroscopy quantify water content. Reconstitution time is recorded because a very slow or incomplete dissolution can signal collapse or aggregation. Stability studies compare samples stored under defined temperature and humidity conditions over months or years.
Regulatory expectations for lyophilized products focus on consistent manufacture and documented stability. Batches are often monitored for moisture, appearance, potency, and sterility where applicable. Process parameters such as shelf temperature, chamber pressure, and drying time are recorded and controlled within validated ranges. Open questions remain about how best to predict long-term stability from short accelerated studies, especially for complex biologics. Variations in freezing rate and ice crystal size can produce differences that are not always visible but may affect performance.
After drying, a lyophilized product is usually sealed under vacuum or an inert gas to limit moisture uptake. Residual water content is measured because small changes can alter chemical stability and cake appearance. Storage temperature depends on the material; many biological products are kept at 2–8 °C, while some require −20 °C or colder. Exposure to ambient humidity during handling can cause the porous solid to absorb water and collapse. Container closures and stoppers are therefore selected for low moisture transmission and compatibility.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 2–8 °C | Common for biological materials; some require −20 °C or colder |
| Residual moisture specification | 0.5–3.0% w/w | Product-specific; measured after drying |
| Common moisture method | Karl Fischer titration | Coulometric or volumetric; detects water content |
| Cake appearance | Uniform and porous | Collapse, meltback, or cracks are deviations |
| Reconstitution time | Seconds to several minutes | Depends on formulation, cake structure, and diluent |
Handling and storage practices aim to keep the cake intact and dry. Vials are typically stored upright at controlled temperatures, often between 2 °C and 8 °C or at -20 °C for longer-term use. Reconstitution involves adding a suitable diluent and gently mixing until the solid dissolves. Shaking or rapid injection of diluent can create foam or damage sensitive molecules. Once reconstituted, the product may require refrigeration and use within a defined period.
Residual moisture is a key quality attribute for lyophilized products. Water that remains after secondary drying can affect chemical stability, cake structure, and shelf life. Karl Fischer titration is a common method for measuring water content in the dried solid. The target range varies by product, but many biologics are dried to between 0.5% and 3% water by weight. Acceptable limits are set during development and confirmed by stability studies.
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.
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.
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.
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.
==== Deka Machines ==== The Deka Machines (デカマシン, Deka Mashin) are vehicle-themed mecha that are dispatched from the Deka Base and can combine into giant robots through either Tokusou Combination (特捜合体, Tokusō Gattai) or Tokusou Transformation (特捜変形, Tokusō Henkei).
== History == Sam Chun Dang Pharm was established on December 29, 1943, to manufacture and sell pharmaceutical products. The company is widely recognized as the first Korean pharmaceutical company to manufacture eye drops. In 1985, SCD constructed a KGMP-certified factory within the Hyannam Pharmaceutical Industrial Complex in Hwaseong, Gyeonggi Province. In 2013, SCD acquired Optus Pharmaceuticals, at the time the leading domestic manufacturer of single-use ophthalmic eye drops. SCD received the European Union Good Manufacturing Practice certification from the UK MHRA in March 2015, and a further EU GMP certificate from Germany's BGV in April 2018, allowing the company to expand into international markets.
== Contents == Like mainstream smoke, sidestream tobacco smoke is made up of many components including carbon monoxide, tar, nicotine, ammonia, benzene, cadmium and 4-aminobiphenyl. Some of the other compounds found in sidestream smoke are: vinylchloride, hydrogen cyanide, arsenic, acrolein, acetaldehyde, formaldehyde, catechol, cresol, hydroquinone, lead, methyl ethyl ketone, nitric oxide, phenol, styrene, toluene, and butane. Exposure to sidestream smoke yields higher concentrations of these compounds as well as increased concentrations of carboxyhemoglobin, nicotine, and cotinine in the blood. When comparing sidestream and mainstream condensate, sidestream has 2–6 times more condensate per gram than mainstream smoke. Due to the incomplete combustion process responsible for the creation of sidestream smoke, there may be exposure to higher concentrations of carcinogens than are typically inhaled directly.
=== Influence of Vladimir Cerrón === Vladimir Cerrón is the General Secretary of Free Peru, who represents the Marxist–Leninist faction of the party. Cerrón was previously the governor of Junín, but was convicted for corruption and given a suspended sentence. Cerrón has repeatedly denied such charges, stating that he's a victim of lawfare and political persecution. The indictment prevents Cerrón from running for public office. During the 2021 Peruvian general election, Castillo distanced himself from Cerrón, saying that Cerrón "will not even be a doorman in any of the institutions of the State." However, Castillo has been accused of appointing government officials and ministers who are close to Cerrón. These include the appointment of Waldemar Cerrón, Vladimir's brother, as Free Peru's spokesman in Congress, despite Waldemar being investigated for money laundering. Waldemar has also been under investigation in Los Dinámicos del Centro, an alleged criminal organization that's investigated for money laundering. The investigations also include Vladimir and then Prime Minister Bellido. Vladimir has accused the investigations of being political persecution. Later, a number of alleged members of Los Dinámicos del Centro escaped from the country. Prime Minister Mirtha Vásquez stated that they have been included in Peru's registry of most wanted fugitives.
== Further reading == Jones, LR; Maddock, SW; Besch, HR Jr (1980). "Unmasking effect of alamethicin on the (Na+,K+)-ATPase, beta-adrenergic receptor-coupled adenylate cyclase, and cAMP-dependent protein kinase activities of cardiac sarcolemmal vesicles". J. Biol. Chem. 255 (20): 9971–9980. doi:10.1016/S0021-9258(18)43488-6. PMID 6253461. Explore structures of Alamethicin at the protein data bank Alamethicin in Norine From "A voltage-gated ion channel model inferred from the crystal structure of alamethicin at 1.5-A resolution." Fox Jr, RO; Richards, FM (1982). "A voltage-gated ion channel model inferred from the crystal structure of alamethicin at 1.5-A resolution". Nature. 300 (5890): 325–30. Bibcode:1982Natur.300..325F. doi:10.1038/300325a0. PMID 6292726. S2CID 4278453. Leitgeb, Balázs; Szekeres, András; Manczinger, László; Vágvölgyi, Csaba; Kredics, László (2007-06-01). "The History of Alamethicin: A Review of the Most Extensively Studied Peptaibol". Chemistry & Biodiversity. 4 (6): 1027–1051. doi:10.1002/cbdv.200790095. ISSN 1612-1880. PMID 17589875. S2CID 40886688.
Sources: en.wikipedia.org
== History == In traditional oil painting as practiced by the Renaissance painter, skin glue was used to seal the canvas. This is necessary because the linseed oil that forms the base of most oil paint contains linolenic acid that will destroy the canvas fibers over time. Renaissance artists also knew that pure size (hide glue) became brittle once dry, and would mix it with oil and chalk to make a "half-ground" for canvases. Pure hide glue was usually applied only to rigid supports like panels. Though this does help to seal the canvas or panel, artists still applied a layer of "oil ground", which was often lead-based paint, in order to provide a binding layer for the final oil paint to adhere to.
Nonbenzodiazepines also bind to the benzodiazepine binding site on the GABAA receptor and possess similar pharmacological properties. While the nonbenzodiazepines are by definition structurally unrelated to the benzodiazepines, both classes of drugs possess a common pharmacophore (see figure to the lower-right), which explains their binding to a common receptor site. Not all benzodiazepines increase the conductance of the GABAA receptor. Flumazenil, an imidazobenzodiazepine, is an antidote for some benzodiazepine overdoses. The structural scaffold can even be used to target receptors other than GABAA.
== Working class history == Detlev Peukert was born in Gütersloh, Eastern Westphalia, the son of Konrad Peukert, a mining engineer from Oederan/Flöha (Saxony), and his wife Ilse (Kramer) Peukert, a secretary from Gütersloh. He grew up in Hamm-Herringen in the Ruhr area. Many of his father's fellow coal miners had been members of either the SPD or KPD, and were sent to concentration camps during the Nazi era. Growing up in the coal miners' milieu, where many so had been sent to concentration camps for anti-Nazi views, left Peukert very interested in the subject of outsiders in the Third Reich, as he wanted to know why so many coal miners chose to oppose the Nazi regime when so many other ordinary people were passive, indifferent or supportive of the Nazi regime. The coal miners of the Ruhr formed a distinctive sub-culture in Germany, known for their defiant, rebellious attitude to authority, left-wing views, and their often confrontational relations with the firm of Krupp AG, Germany's biggest corporation, which in turn was owned by the Krupp family, Germany's richest family. As a student, Peukert studied under Hans Mommsen at Bochum university, and began teaching at the University of Essen starting in 1978. As a "68er" whose politics were defined by the student protests of 1968, Peukert was active in left-wing politics and joined the German Communist Party (DKP).
The gold standard for diagnosis of cirrhosis is a liver biopsy. This is usually carried out as a fine-needle approach, through the skin (percutaneous), or internal jugular vein (transjugular). Endoscopic ultrasound-guided liver biopsy (EUS), using the percutaneous or transjugular route, has become a good alternative to use. EUS can target liver areas that are widely separated, and can deliver bi-lobar biopsies. A biopsy is not necessary if the clinical, laboratory, and radiologic data suggest cirrhosis. Furthermore, a small but significant risk of complications is associated with liver biopsy, and cirrhosis itself predisposes to complications caused by liver biopsy. Once the biopsy is obtained, a pathologist will study the sample. Cirrhosis is defined by its features on microscopy: (1) the presence of regenerating nodules of hepatocytes and (2) the presence of fibrosis, or the deposition of connective tissue between these nodules. The pattern of fibrosis seen can depend on the underlying insult that led to cirrhosis. Fibrosis can also proliferate even if the underlying process that caused it has resolved or ceased. The fibrosis in cirrhosis can lead to destruction of other normal tissues in the liver, including the sinusoids, the space of Disse, and other vascular structures, which leads to altered resistance to blood flow in the liver, and portal hypertension.
=== Food === Fumaric acid has been used as a food acidulant since 1946. It is approved for use as a food additive in the EU, USA, Australia, and New Zealand. As a food additive, it is used as an acidity regulator and can be denoted by the E number E297. It is generally used in beverages and baking powders for which requirements are placed on purity. Fumaric acid is used in the making of wheat tortillas as a food preservative and as the acid in leavening. It is generally used as a substitute for tartaric acid and occasionally in place of citric acid, at a rate of 1 g of fumaric acid to every ~1.5 g of citric acid, in order to add sourness, similarly to the way malic acid is used. As well as being a component of some artificial vinegar flavors, such as "Salt and Vinegar" flavored potato chips, it is also used as a coagulant in stove-top pudding mixes. The European Commission Scientific Committee on Animal Nutrition, part of DG Health, found in 2014 that fumaric acid is "practically non-toxic" but high doses are likely nephrotoxic after long-term use.
Sources: en.wikipedia.org
2 SO3 + RCH2OH → RCH2OSO2−O−SO3H RCH2OSO2−O−SO3H → RCH2OSO3H + SO3 Several million tons of fatty acid sulfates are produced in this way annually. The most common example is sodium dodecylsulfate (SDS) derived from lauryl alcohol.
=== Pharmacodynamics === Nor-LSD showed 5- to 29-fold lower affinity for the serotonin 5-HT2 receptor compared to LSD (Ki = 30–158 nM vs. 5.4 nM, respectively). It also showed affinity for the serotonin 5-HT1 receptor. In another more recent study however, nor-LSD showed similar or even higher affinities, activational potencies, and/or efficacies at the serotonin 5-HT1A, 5-HT2A, and 5-HT2B receptors as LSD, whereas it showed 36-fold lower affinity for the serotonin 5-HT2C receptor compared to LSD. Nor-LSD failed to completely substitute for LSD in rodent drug discrimination tests even at very high doses. The greatest degree of substitution with nor-LSD was 75% at a dose of 7,420 nM/kg, whereas 100% substitution occurred with LSD at a dose of 186 nM/kg (a 40-fold lower dose). The ED50Tooltip median effective dose was 2,594 nM/kg for nor-LSD and 46 nM/kg for LSD. Hence, nor-LSD was approximately 56-fold less potent than LSD in terms of producing LSD-like effects in rodents and failed to produce full LSD-like effects even at the highest assessed dose. In another study, nor-LSD failed to produce LSD-like electroencephalogram (EEG) changes in rabbits.
=== Complications of executions and cessation of supply of lethal injection drugs === By early 2014, a number of botched executions involving lethal injection and a rising shortage of suitable drugs had some U.S. states reconsidering lethal injection as a form of execution. Tennessee, which had previously offered inmates a choice between lethal injection and the electric chair, passed a law in May 2014 that gave the state the option to use the electric chair if lethal injection drugs were either unavailable or declared unconstitutional. At the same time, Wyoming and Utah were considering the use of execution by firing squad in addition to other existing execution methods. In 2016, Pfizer joined over 20 American and European pharmaceutical manufacturers that had previously blocked the sale of their drugs for use in lethal injections, effectively closing the open market for FDA-approved manufacturers for any potential lethal execution drug. In the execution of Carey Dean Moore on August 14, 2018, the State of Nebraska used a novel drug cocktail comprising diazepam, fentanyl, cisatracurium, and potassium chloride, over the strong objections of the German pharmaceutical company Fresenius Kabi. Potassium acetate had been incorrectly used in place of potassium chloride in Oklahoma in January 2015 for the execution of Charles Frederick Warner. In August 2017, the State of Florida first used the drug in the execution of Mark James Asay using a combination of etomidate, rocuronium bromide, and potassium acetate as part of a new protocol.
Valorous Unit Award, Streamer embroidered AFGHANISTAN 2011–2012 Meritorious Unit Commendation (Army), Streamer embroidered WAR ON TERRORISM 2011–2012 Company A, 3d Special Forces Battalion entitled to: Presidential Unit Citation (Army), Streamer embroidered AFGHANISTAN JUL-DEC 2016 Valorous Unit Award, Streamer embroidered AFGHANISTAN JUN-AUG 2010 Company B, 3d Special Forces Battalion entitled to: Meritorious Unit Commendation (Army), Streamer embroidered AFGHANISTAN AUG 2010-APR 2011 4th Special Forces Battalion entitled to:
Sources: en.wikipedia.org
Most are held in sealed containers at controlled temperatures, often 2–8 °C, while some require frozen storage. Protection from moisture and light helps preserve the dry matrix. Exact conditions are set by the manufacturer or study protocol.
Cake collapse suggests the material exceeded its collapse temperature during drying or later absorbed moisture. It can lead to slower reconstitution, uneven moisture, and reduced stability. Appearance alone may not reveal the cause, so process records and moisture tests are used together.
Some residual moisture is common and may be acceptable within a defined range. Very low moisture can alter stability or increase brittleness, while high moisture promotes hydrolysis and microbial risk. Specifications are based on product-specific stability data.
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.