The short version of primary drying fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-14 and is reviewed periodically as new material appears.
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.
Freeze-drying is distinct from simple evaporation and from spray drying. Evaporation removes water at temperatures above freezing, while spray drying rapidly dries droplets in a heated gas stream. Lyophilization avoids high temperatures, which can be useful for heat-sensitive materials such as proteins, vaccines, and some foods. The porous cake produced by sublimation dissolves or rehydrates more quickly than a dense dried mass. Not all materials tolerate freezing or the pH shifts that can occur as solutes concentrate during ice formation.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and fixes the structure of the sample. After freezing, primary drying lowers pressure so ice changes directly to vapor without passing through a liquid phase. Secondary drying then removes bound water that remains after ice sublimation. The result is a dry, porous solid that often retains its original shape.
The low pressure used during drying allows water vapor to move from the ice surface to a cold condenser. Energy supplied as heat drives sublimation but must stay below the collapse temperature of the frozen matrix. If the product becomes too warm, the frozen structure may soften or melt, reducing pore formation and slowing drying. Formulations often include bulking agents, stabilizers, or buffers to support a rigid cake. The final moisture content depends on formulation, freezing rate, and the length of secondary drying.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white porous cake | Color and texture vary with formulation. |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity, excipients, and diluent. |
| Typical moisture level | 0.5-3% w/w | Lower values suit hydrolysis-sensitive materials. |
| Common moisture method | Karl Fischer titration | Coulometric mode is common for low water levels. |
| Typical storage temperature | 2-8 °C or ambient | Some products require frozen storage; protect from humidity. |
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.
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.
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.
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.
Stability programs monitor lyophilized products under defined temperature and humidity conditions over time. Real-time studies at recommended storage conditions are the reference, while accelerated studies provide early signals of degradation pathways. Because a dry cake can still undergo oxidation, hydrolysis, or aggregation, stability depends on residual moisture, excipients, and container headspace. Open questions include how best to predict long-term stability from short accelerated runs and how vial-to-vial variability affects shelf life. Current guidance treats these predictions as product-specific rather than universally generalizable.
Freeze-dried materials are hygroscopic to varying degrees and can take up moisture after drying. Storage therefore often uses sealed glass vials, rubber stoppers, and crimp seals to limit contact with ambient humidity. A desiccant may be included for moisture-sensitive products, although it is not universal. Controlled room temperature is sufficient for many lyophilizates, while others require refrigeration or freezing. Moisture ingress remains a primary cause of cake collapse, chemical degradation, and loss of reconstitution performance.
Quality assessment of a lyophilized product includes cake appearance, residual moisture, reconstitution time, and container closure integrity. A uniform, porous cake suggests that freezing and drying stayed within the formulation's design space. Cracks, shrinkage, meltback, or a glassy film can indicate thermal abuse or a formulation problem. Analysts also test for subvisible particles and sterility when the product requires those specifications. Visual inspection alone cannot confirm biological activity or chemical stability, so it is combined with analytical methods.
The process relies on the phase diagram of water, where the triple point marks the conditions at which ice, liquid water, and vapor coexist. By maintaining pressure below this point, typically around 0.01 to 0.1 millibar, sublimation becomes the dominant mechanism. Formulations often include excipients such as sugars or polymers that act as lyoprotectants and bulking agents. These additives help preserve the structure of the active ingredient and prevent collapse during drying. The choice of excipient and freezing rate influences the final cake morphology and stability.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
The procedure is illustrated by the synthesis of a dipeptide library using the same three amino acids as building blocks in both cycles. Each component of this library contains two amino acids arranged in different orders. The amino acids used in couplings are represented by yellow, blue and red circles in the figure. Divergent arrows show the division of solid support resin (green circles) into equal portions, vertical arrows mean coupling, and convergent arrows represent the mixing and homogenizing of the portions of the support. The figure shows that, in the two synthetic cycles, 9 dipeptides are formed. In the third and fourth cycles, 27 tripeptides and 81 tetrapeptides would form respectively. The "split-mix synthesis" has several outstanding features:
The risk of experiencing severe withdrawal symptoms is high if a patient has become physically or mentally dependent and discontinues tapentadol abruptly. These symptoms can range from mild discomfort to more serious health issues, making abrupt cessation dangerous. When a person has been using tapentadol regularly for an extended period of time, tapering off the drug gradually is generally recommended. This approach allows the body to adjust to lower doses over time, minimizing the risk of withdrawal symptoms and ensuring a safer transition away from tapentadol. Gradual withdrawal helps to avoid the shock to the system that comes with abrupt discontinuation, ultimately making the process more manageable for a person who has developed a dependence. The symptoms of tapentadol withdrawal are typical of other opioids and can include anxiety, restlessness, fever or chills, joint pain, nausea or vomiting, loss of appetite, runny nose, stomach cramps, sweating, tremor, or insomnia. However, tapentadol withdrawal symptoms may be more intense and prolonged when compared with more typical opioids such as codeine or oxycodone, in some respects, due to the fact that tapentadol acts also as norepinephrine reuptake inhibitor (NRI). People withdrawing from a tapentadol dependency may experience both typical opioid withdrawal symptoms, such as fever or nausea, along with symptoms associated more commonly with the discontinuation of drugs which block the reuptake of norepinephrine.
Alteplase binds to fibrin in a blood clot and activates the clot-bound plasminogen. Alteplase cleaves plasminogen at the site of its Arg561-Val562 peptide bond to form plasmin. Plasmin is a fibrinolytic enzyme that cleaves the cross-links between polymerized fibrin molecules, causing the blood clot to break down and dissolve, a process called fibrinolysis.
==== Academic licencing, licence steering and AI commercialisation ==== The use of academic research for Large Language Models (LLMs) has sparked debate within the Open Access movement. Academics accuse publishers of steering authors towards restrictive licences to retain exclusive commercial rights for AI training deals. In 2024, publishers like Taylor & Francis announced lucrative AI training partnerships, often without consulting authors. This dynamic complicates copyright litigation, as seen in the US when Elsevier sued Meta over Llama AI models, acting as the class representative due to exclusive commercial rights granted by authors.
== Other functions == In Cullen's paper "Granzymes in Cancer and Immunity" he discusses how granzyme A has been known to be found in elevated levels within patients who currently have an infectious disease and/or in a pro-inflammatory state. Granzymes have also been found to help initiate the inflammatory response. "For example, rheumatoid arthritis patients have increased levels of granzyme A in the synovial fluid of swollen joints". When granzymes are in an extracellular state they have the ability to activate macrophages and mast cells to initiate the inflammatory response. The interaction between the granzymes and somatic cells are still unexplainable but advances in understanding the process are being made constantly. Other granzymes like granzyme K have been found in high levels of patients who have gone septic. Granzyme H has been found to have a direct correlation with patients who have a viral infection. Scientists are able to conclude that granzyme H specializes in detecting 'proteolytic degradation' which is found in viral proteins. Cullen further states in his paper that granzymes may have a role in immunomodulation, or the job of maintaining homeostasis in the immune system during an infection. "In humans, loss of perforin function leads to a syndrome called familial hemophagocytic lymphohistiocytosis […]". This syndrome can lead to death because both T cells and macrophages multiply to fight the pathogen, resulting in harmful levels of proinflammatory cytokines.
Sources: en.wikipedia.org
=== Alternative modulations === The DASH7 Alliance policy forbids the addition of proprietary or licensable modulation techniques in the official DASH7 Alliance Protocol. However, the layered structure of the protocol allows simple integration of alternative modulations, such as LoRa, under the network layer (D7ANL).
Organized crime refers to groups of centralized enterprises that engage in, and aim to profit from, illegal activities. Some forms of organized crime exist simply to meet demand for illegal goods or to facilitate trade in products and services banned by the state, such as illegal drugs or firearms. In other cases, criminal organizations force people to do business with them, as when gangs extort protection money from shopkeepers. In the United States, the Organized Crime Control Act (1970) defines organized crime as "[t]he unlawful activities of [...] a highly organized, disciplined association [...]". Criminal activity as a structured process is referred to as racketeering. In the UK, police estimate that organized crime involves up to 38,000 people operating in 6,000 various groups. Historically, the largest organized crime force in the United States has been Cosa Nostra (Italian-American Mafia), but other transnational criminal organizations have also risen in prominence in recent decades. A 2012 article in a U.S. Department of Justice journal stated that: "Since the end of the Cold War, organized crime groups from Russia, China, Italy, Nigeria, and Japan have increased their international presence and worldwide networks or have become involved in more transnational criminal activities.
Methylation of 3-propylpyrazole-5-carboxylic acid ethyl ester with hot dimethyl sulfate Hydrolysis with aqueous sodium hydroxide (NaOH) to free acid Nitration with oleum/fuming nitric acid Carboxamide formation with refluxing thionyl chloride/NH4OH Reduction of nitro group to amino group Acylation with 2-ethoxybenzoyl chloride Cyclization Sulfonation to the chlorosulfonyl derivative Condensation with 1-methylpiperazine.
In 1977, Bush established Arbusto Energy, a small oil exploration company, which began operations in 1978. He later changed the name to Bush Exploration. In 1984, his company merged with the larger Spectrum 7, and Bush became chairman. The company was hurt by decreased oil prices, and it folded into Harken Energy Corporation, with Bush becoming a member of Harken's board of directors. Questions of possible insider trading involving Harken arose, but a Securities and Exchange Commission investigation concluded that the information Bush had at the time of his stock sale was not sufficient to constitute insider trading. In April 1989, Bush arranged for a group of investors to purchase a controlling interest in Major League Baseball's Texas Rangers for $89 million and invested $500,000 himself to start. He was then the managing general partner for five years. He actively led the team's projects and regularly attended its games, often choosing to sit in the open stands with fans. Bush's sale of his shares in the Rangers in 1998 brought him over $15 million from his initial $800,000 investment. In the early or mid 1990s, before his gubernatorial campaign, Bush briefly considered running for Commissioner of Baseball.
The Cambridge University undergraduate newspaper also ran its own short article on the discovery on Saturday, May 30, 1953. Bragg's original announcement at a Solvay Conference on proteins in Belgium on April 8, 1953, went unreported by the press. In 1962 Watson, Crick, and Maurice Wilkins jointly received the Nobel Prize in Physiology or Medicine for their determination of the structure of DNA.
Sources: en.wikipedia.org
== Role in treatment of disease == A 1996 study by McPhee et al. suggested that stercobilin and other related pyrrolic pigments — including urobilin, biliverdin, and xanthobilirubic acid — has potential to function as a new class of HIV-1 protease inhibitors when delivered at low micromolar concentrations. These pigments were selected due to a similarity in shape to the successful HIV-1 protease inhibitor Merck L-700,417 (N,N-bis(2-hydroxy-1-indanyl)-2,6-diphenylmethyl-4-hydroxy-1,7-heptandiamide). Further research is suggested to study the pharmacological efficacy of these pigments.
On 15 April 2012, Marco Antonio Reyes, reported to be the head of the cartel's gunmen, was captured in Veracruz along with five of his associates. The arrests also led to the capture of three other cartel members, including the head of the cartel's operations in the Veracruz cities of Veracruz and Boca del Río. On 30 January 2014, Mexican authorities arrested Rubén Oseguera González (alias "El Menchito"), the second-in-command in the cartel and the son of Nemesio Oseguera Cervantes, the organization's leader. Rubén was eventually extradited to the United States in 2020, where he was convicted in two criminal trials which took place in September 2024, and given a life sentence in March 2025. On 1 May 2015, a Mexican army helicopter was shot at and forced to land in what Jalisco's Governor Aristoteles Sandoval described as "a reaction to an operation to detain leaders of this cartel". On 28 May 2018, they arrested Rosalinda González Valencia, who is the wife of Cervantes. From 2015 to 2025, prominent CJNG leaders who were also brother-in-laws of El Mencho, Abigael González Valencia, Gerardo González Valencia, and José González Valencia was arrested and extradited to the United States at later dates. While in the United States, Gerardo was given a life sentence in July 2023 after accepting a guilty plea related to drug trafficking charges, while José was given a 30 year sentence after accepting a guilty plea to less extreme drug trafficking charges in June 2025.
== Effect on cancer == Initially, MAFs were thought to increase a macrophage’s cytotoxic response, allowing enhanced clearance of the tumor cells. However, they also have wider ranging effects. Chronic inflammation associated with activated macrophages may lead to the development of neoplasia, such as those found surrounding tuberculosis scars. Dysregulation of macrophage activation may cause increased inflammation and eventual neoplasia. Moreover, macrophages infiltrating the tumor microenvironment can transition towards a regulatory phenotype. Regulatory macrophages produce Interleukin 10, which can inhibit cytotoxic responses of other lymphocytes to cancer cell antigens. The stromal reaction surrounding a tumor, as well as prostaglandins and hypoxia may play a role in this transition. Epithelial-mesenchymal transition has been found to be influenced by all types of macrophages, which cause both pro and anti-inflammatory responses that can promote EMT.
The chromerids are a group of algae known from Australian corals which comprise some close photosynthetic relatives of the apicomplexans. The first member, Chromera velia, was discovered and first isolated in 2001. The discovery of Chromera velia with similar structure to the apicomplexans, provides an important link in the evolutionary history of the apicomplexans and dinophytes. Their plastids have four membranes, lack chlorophyll c and use the type II form of RuBisCO obtained from a horizontal transfer event.
=== Che–Cl === Zhijian James Chen (b. 1966). Chinese-American biochemist at the University of Texas Southwestern Medical Center, known discovering mechanisms by which nucleic acids trigger innate and autoimmune responses from the interior of a cell. Member Natl. Acad. Sci. USA. Albert Chibnall FRS (1894–1988), British biochemist known for his work on the nitrogen metabolism of plants. Ruth Chiquet-Ehrismann (1954–2015), Swiss biochemist and cell biologist working on interactions in the extracellular matrix. Cyrus Chothia FRS (1942–2019). British biochemist at Cambridge known for work on protein structure. Gilbert Chu (b. 1946). American biochemist at Stanford, known for investigating how cells react to DNA damage from radiation. George M. Church (b. 1954). American geneticist at Harvard and MIT, known for pioneering personal genomics and synthetic biology. Member Natl. Acad. Sci. USA. Aaron Ciechanover (b. 1947). Israeli biochemist at the Technion, Haifa, known for work on protein turnover. Nobel Prize for Chemistry in 2004. Foreign associate Natl. Acad. Sci. USA. Vintilă Ciocâlteu (1890–1947) Roumanian physician, biochemist, researcher, professor, and author. Hans Thacher Clarke (1887–1972), British-born American biochemist at Columbia University, known for the Eschweiler–Clarke reaction. Member Natl. Acad. Sci. USA. Jane Clarke (b. 1950). Biochemist at Cambridge known for work on folding and assembly of proteins. Steven Clarke (b. 1949). American biochemist at UCLA, known for work on molecular damage and molecular repair mechanisms. Roy Elwood Clausen (1891–1956).
Sources: en.wikipedia.org
Karl Fischer titration is a common method, using coulometric or volumetric detection. Thermogravimetric analysis can also measure weight loss on heating. Results depend on sample handling because the dried solid can absorb moisture quickly.
The porous cake readily absorbs water vapor from air, which can reduce stability or cause collapse. Vials are sealed with stoppers and crimp seals, sometimes under vacuum or inert gas. Packaging also protects against oxygen and mechanical damage.
Collapse occurs when the product temperature rises above its collapse threshold during primary drying. The ice matrix loses structure, and the cake may shrink or melt back. Formulation excipients and freezing rate influence collapse threshold.
Lyophilization relies on sublimation, so water moves from solid ice to vapor without becoming liquid. The material is frozen, pressure is reduced, and controlled heat is supplied. Vapor is captured on a cold condenser, leaving a dry porous solid.