The short version of secondary drying fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-09 and is reviewed periodically as new material appears.
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.
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.
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 |
|---|---|---|
| Typical storage temperature | 2–8 °C | Some products tolerate room temperature or require −20 °C. |
| Residual moisture method | Karl Fischer titration | Coulometric or volumetric; specific for water. |
| Cake appearance | Uniform porous plug | Collapse, shrinkage, or meltback indicates process deviation. |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity, diluent, and formulation. |
| Primary container | Glass vial with elastomeric stopper | Crimp seal limits moisture ingress. |
Handling practices aim to prevent moisture ingress and mechanical damage. Vials should remain stoppered and crimped until use, and reconstitution should follow the labeled diluent and volume. Shipping may involve temperature-controlled containers and desiccants, but direct contact between desiccant and product is avoided. Regulatory guidance expects documented storage conditions, excursion assessments, and stability commitments. Open questions remain about how best to predict long-term stability from short accelerated studies for every formulation class.
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.
Freezing is the first stage and sets the ice structure that later becomes the pore network. The formulation is cooled below its freezing point, often with a controlled ramp, and solutes concentrate as ice forms. Primary drying then lowers chamber pressure and supplies heat to sublime the ice. The product temperature must stay below its collapse or eutectic temperature to prevent structural loss. Secondary drying raises the temperature modestly to remove bound water and achieve a low residual moisture.
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.
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.
Lyophilized products are typically stored as sealed solids in vials or syringes. Moisture ingress is a major concern because many dried cakes are hygroscopic and can lose stability when exposed to humid air. Storage temperature depends on the formulation; some products are kept refrigerated, while others are stable at room temperature. Container closure integrity and headspace moisture are often monitored. Light protection may also be required for some photosensitive materials.
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.
Surgical technique – the bilobed flap The design of the bilobed flap co-ordinates its lobes with the long axis of the nasal defect (wound); each lobe of the flap is emplaced at a 45-degree angle to the axis. The two lobes of the bilobed flap rotate along an arc, of which all points are equidistant from the apex of the nasal defect.
A new format concept, A&W Great Food Restaurants, was developed. Ten corporate-owned locations were opened to test the concept: a sit-down, upscale, family-theme restaurant with a large salad bar and homemade ice cream. The first such branch opened in 1978 (1979, according to some sources) at the Lake Forest Shopping Mall in Gaithersburg, Maryland. Emphasis in these restaurants was made on low-calorie foods that covered almost the entirety of the foods found in the fast-food spectrum, except pizza. By 1986, there were plans to have 250 to 300 locations within ten years.
In the 2024 presidential election, Americans aged 18 to 29 voted for Kamala Harris by a margin of only four points, according to exit polls conducted by the Associated Press. Donald Trump and his Republican Party made considerable gains among young voters, especially young men and European Americans. Among Gen-Z women, while those of ethnic-minority backgrounds overwhelmingly supported Harris, those of European ancestry were evenly split between Harris and Trump. This election has broken the historical trend of young people generally voting for Democrats. Generation Z has been shifting towards the right since 2020. Even so, polls conducted after that election showed that the majority of Generation Z disapproved of the performance of President Donald Trump because he had failed to address their concerns about the economy, especially inflation and the cost of living.
== Examples == Inflammation is usually indicated by adding the suffix "itis", as shown below. However, some conditions, such as asthma and pneumonia, do not follow this convention. More examples are available at List of types of inflammation.
The kynurenine pathway is a metabolic pathway leading to the production of nicotinamide adenine dinucleotide (NAD+). Metabolites involved in the kynurenine pathway include tryptophan, kynurenine, kynurenic acid, xanthurenic acid, quinolinic acid, and 3-hydroxykynurenine. The kynurenine pathway is responsible for about 95% of total tryptophan catabolism. Disruption in the pathway is associated with certain genetic and psychiatric disorders.
Sources: en.wikipedia.org
=== Protein tags === BCCP (Biotin Carboxyl Carrier Protein), a protein domain biotinylated by BirA enabling recognition by streptavidin BromoTag, a "bump-and-hole" mutated version of the second bromodomain of Brd4, Brd4-BD2 L387A, that can be highly selectively bound by tag-specific PROTAC degrader AGB1 to form a ternary complex between the "BromoTagged" protein and the E3 ligase VHL, leading to ubiquitination of the tagged protein and its subsequent rapid and effective proteasomal degradation in cells. FAST (Fluorescence-Activating and absorption-Shifting Tag), a mutated photoactive yellow protein (PYP) that reversibly binds cognate fluorogenic ligands CL7-tag, an engineered variant of Colicin E7 that has a strong binding affinity and specificity for immobilized Immunity Protein 7 (Im7). Glutathione-S-transferase-tag, a protein which binds to immobilized glutathione Green fluorescent protein-tag, a protein which is spontaneously fluorescent and can be bound by nanobodies HaloTag, a mutated bacterial haloalkane dehalogenase that covalently attaches to haloalkane substrates SNAP-tag, a mutated eukaryotic DNA methyltransferase that covalently attaches to benzylguanine derivatives CLIP-tag, a mutated eukaryotic DNA methyltransferase that covalently attaches to benzylcytosine derivatives HUH-tag, a sequence-specific single-stranded DNA binding protein that covalently binds to its target sequence Maltose binding protein-tag, a protein which binds to amylose agarose Nus-tag Thioredoxin-tag Fc-tag, derived from immunoglobulin Fc domain, allow dimerization and solubilization.
== Coevolution == Coevolution is the long-term outcome of the algae-bacteria interaction. Algae and bacteria interact through mutualism, competition, and antagonistic interactions. Bacteria have evolved mechanisms to utilize algal organic matter or lyse algal cells, while algae have developed defence mechanisms such as resting stages, induced resistance, and chemical signalling responses. This reciprocal adaptation is an evolutionary arms race between algae and bacteria.
14 August – The annual Government Expenditure and Revenue Scotland report shows a public spending deficit of £22.7bn for Scotland during 2023, an increase of £3.6bn from the previous year. The Scottish Government confirms it will follow the UK government by scrapping universal winter fuel payments for pensioners, with the benefit to be means tested. Staff working on Edinburgh's tram network vote to take strike action over a lack of toilet breaks. 15 August – A shipwreck, believed to be that of HMS Hawke, which was sunk by a torpedo during World War I, has been found off the Aberdeenshire coast. 16 August – 2024 Scottish Conservatives leadership election: Four of the six candidates running for the position of Scottish Conservative leader call for the race to be paused after claims about Douglas Ross's behaviour as leader. The claims concern a report that in July 2023 Ross had asked for the leader of Moray council, Kathleen Robertson, to stand down as the prospective parliamentary candidate for Moray West, Nairn and Strathspey. Meghan Gallacher resigns as the party's deputy leader, citing a "potential risk to the reputation of our party and the leadership contest" after reports that Ross had previously suggested Russell Findlay should succeed him. Developers working on HM Prison Highland in Inverness have uncovered a prehistoric settlement believed to be around 2,000 years old.
== Overdose == LGD-4033 has been assessed in clinical trials at single doses ranging from 0.1 to 22 mg and at repeated doses ranging from 0.1 to 2 mg/day for 3 to 12 weeks. The drug sold via black-market Internet suppliers and used non-medically is often taken at much higher doses than those used in repeated-dose clinical trials (e.g., 5–10 mg/day), with unknown adverse effects and risks.
== Legality, ethics and politics == The results of federally mandating drug testing were similar to the effects of simply extending to the trucking industry the right to perform drug tests, and it has been argued that the latter approach would have been as effective at lower cost. Psychologist Tony Buon has criticized the use of workplace drug testing on a number of grounds, including:
Sources: en.wikipedia.org
== Side effects == Side effects of vosilasarm in preliminary clinical studies in women with metastatic breast cancer have included vomiting (27%), dehydration (27%), constipation, decreased appetite and weight loss (27%), hypophosphatemia, decreased sex hormone-binding globulin (SHBG) levels (100%), increased prostate-specific antigen (PSA) levels (80%), and abnormal liver function tests, including elevated aspartate aminotransferase (59%), elevated alanine aminotransferase (46%), and elevated total blood bilirubin (27%). In gonadally intact male cynomolgus monkeys, vosilasarm suppressed testosterone levels by around 50% (from ~600–800 ng/dL to ~200–300 ng/dL) across three dose levels (0.01 mg/kg, 0.1 mg/kg, and 1.0 mg/kg). Changes in serum lipids, including of triglycerides, LDL cholesterol, and HDL cholesterol were also observed. Elevated liver enzymes were minimally observed in monkeys. A number of case reports of liver toxicity with non-medical use of vosilasarm have been published. A case report of acute myocarditis with non-medical use of vosilasarm also exists.
The crossover video game Lego Dimensions, which incorporates the use of Lego minifigures with a special gamepad, includes Portal-themed elements, as first demonstrated during its Electronic Entertainment Expo 2015 trailer. A Portal-themed level appears as part of the main story campaign, with GLaDOS playing a significant role in the game's plot. A Chell minifigure was released that comes packaged with buildable sentry turret and companion cube; the figure unlocks an additional level and open-world area based on the series when used in-game. The Portal levels include Easter eggs based on Doug Rattmann hiding himself away. The game also features a new song written by Jonathan Coulton and performed by Ellen McLain that plays over the end credits. The series' main antagonist, GLaDOS, was included as the dealer in Poker Night 2. This game features Portal themed unlockables such as playing cards, table and room. Wheatley is also featured as a bargaining chip. A Portal based pinball table for Zen Pinball 2, Pinball FX2, and Pinball FX3 was developed by Zen Studios in collaboration with Valve. GLaDOS guest stars in Defense Grid: The Awakening in a full-story expansion. A cosmetic set based on the Companion Cube was released as a visual replacement for the "Io" character in Valve's multiplayer online battle arena game, Dota 2. P-Body is a playable character in the Windows release of Super Bomberman R.
Urocortin III, a 38–41 amino acid peptide, is a member of the CRF (corticotropin-releasing factor), also known as CRH (corticotropin-releasing hormone) family of peptides, with a long evolutionary lineage. Separate chromosomes harbouring two exons each are home to the genes encoding UCN, UCN2, and UCN3. A gene on human chromosome 10p15 at location 5.40 Mb encodes the urocortin, UCN III, which has been discovered more recently. A 161 amino acid precursor is produced when the UCN III gene is translated. Mature UCN III with 38 or 41 amino acids would be produced by proteolytic cleavage between arginine- or threonine-lysine residues. Human plasma contains both the 38 and 41 amino acid forms of UCN III, although the 38 amino acid form is more prevalent, according to findings from high-performance liquid chromatography. Each urocortin peptide has a distinct expression location and function, yet they all share conserved structural similarity. Urocortins' structures, as determined by nuclear magnetic resonance, exhibit alpha-helical secondary structures, which support biological activity and binding selectivity.
The statue of Augustus of Prima Porta was discovered within the Villa of Livia in 1863. Little is known about the discovery itself and its immediate aftermath, as the incomplete archaeological journals leave ambiguous evidence for modern historians. The statue was first publicized by the German archaeologist Wilhelm Henzen in 1863 in the Bulletino dell'Instituto di Corrispondenza Archaeologica. The exact location of the statue within the villa is unknown. Suggested sites are the underground complex, a placement near a staircase, the villa's atrium, or in a laurel grove on the southeast corner of Prima Porta hill. Scholars have stated that the last one is relatively unconvincing compared with the first three. The theory that Augustus's statue was found in the underground complex of the villa is based on a hypothesis that Augustus holds a laurel branch instead of a spear in his left hand. Scholars have noted that if this hypothesis is correct, then Villa of Livia must have been decorated with laurel groves and that the reason of the decoration is the omen of the gallina alba (Latin: white hen). Recent excavations have discovered the remnants of pots used to plant laurel on the edge of the Prima Porta hill in front of the underground complex, which Reeder believes suggests the possibility of the existence of laurel groves in the villa and makes it likely that the statue was located in the underground complex.
Sources: en.wikipedia.org
Karl Fischer titration is widely used because it is specific for water and works at low levels. Loss on drying is simpler but less specific, since volatile solvents or decomposition products can also be lost.
Collapse can occur when the product temperature exceeds its critical formulation temperature during drying. The porous structure then melts or shrinks, reducing reconstitution speed and sometimes altering stability.
No. Low moisture slows many degradation pathways but does not stop oxidation, hydrolysis, or physical changes completely. Storage temperature, container closure, and formulation still influence 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.