Everything below concerns Sublimation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-06. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying; lyophilisation; cryodesiccation | Regional spelling and historical terms. |
| Primary drying pressure | 0.05-0.5 mbar (5-50 Pa) | Kept below the triple point of water; product-specific. |
| Shelf temperature range | -40 to +40 °C | Freezing, primary, and secondary stages use different set points. |
| Cycle duration | 12-72 hours | Depends on fill volume, formulation, and equipment. |
| Condenser temperature | -50 to -80 °C | Must remain below the product's ice temperature. |
A formulation often contains excipients that protect the active ingredient during freezing and drying. Bulking agents provide structure, while lyoprotectants stabilize sensitive molecules. The freezing step can produce ice crystals whose size and distribution affect the drying rate, and cycle design includes freezing, annealing, and drying phases. If the product temperature rises above a critical value, the cake may collapse or lose its porous structure. Successful lyophilization therefore depends on the interaction between formulation, equipment, and cycle design.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen to convert liquid water into ice. Next, the pressure is reduced below the triple point of water so that ice changes directly into vapor without passing through a liquid phase. This step is called primary drying. The result is a porous solid or cake that retains the original shape of the frozen solution.
After primary drying, secondary drying removes water that remains bound to the material. This stage raises the shelf temperature while maintaining low pressure, which encourages desorption of unfrozen water. Residual moisture can be reduced to a low percentage, improving stability for many products. The process parameters, including freezing rate, shelf temperature, and chamber pressure, influence the final pore structure and reconstitution behavior. Control of these variables helps prevent collapse or meltback during drying.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
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.
High speed homogenization or ultrasonication is used to form small particle size in the nanoparticle suspension. Once the suspension is stable, the solvents are evaporated using either continuous magnetic stirring at room temperature, or by reducing the ambient pressure. The table below displays how nanocapsules exhibit different traits based on the method by which they were prepared. Nanocapsule types vary by size, drug concentration, and active substance release time.
=== Difficulties in diagnosis === Cerebrospinal fluid (CSF) analysis remains the gold standard for the diagnosis of leptomeningeal disease (LMD). CSF is most commonly obtained via lumbar puncture, with cytological examination used to identify malignant cells. In addition to cytology, abnormalities in CSF cell count and biochemical parameters- particularly elevated protein levels - are observed in approximately 90% of LMD cases and provide supportive diagnostic evidence. Despite this, definitive diagnosis remains challenging due to the limited sensitivity of initial CSF cytology and the heterogeneity of clinical presentation. Magnetic resonance imaging (MRI) is typically employed as the first-line diagnostic modality due to its non-invasive nature; however, its diagnostic performance is moderate, with reported sensitivity and specificity of approximately 75% and 77%, respectively.
Colombian literature dates back to pre-Columbian era; a notable example of the period is the epic poem known as the Legend of Yurupary. In Spanish colonial times, notable writers include Juan de Castellanos (Elegías de varones ilustres de Indias), Hernando Domínguez Camargo and his epic poem to San Ignacio de Loyola, Pedro Simón and Juan Rodríguez Freyle. Post-independence literature linked to Romanticism highlighted Antonio Nariño, José Fernández Madrid, Camilo Torres Tenorio and Francisco Antonio Zea. In the second half of the nineteenth century and early twentieth century the literary genre known as costumbrismo became popular; great writers of this period were Tomás Carrasquilla, Jorge Isaacs and Rafael Pombo (the latter of whom wrote notable works of children's literature). Within that period, authors such as José Asunción Silva, José Eustasio Rivera, León de Greiff, Porfirio Barba-Jacob and José María Vargas Vila developed the modernist movement. In 1872, Colombia established the Colombian Academy of Language, the first Spanish language academy in the Americas. Candelario Obeso wrote the groundbreaking Cantos Populares de mi Tierra (1877), the first book of poetry by an Afro-Colombian author. Between 1939 and 1940 seven books of poetry were published under the name Stone and Sky in the city of Bogotá that significantly influenced the country; they were edited by the poet Jorge Rojas.
=== Discovery of GLP-2 actions leading to Short Bowel Syndrome treatments === In 1996, Drucker also discovered the first biological actions for GLP-2, demonstrating that it augmented crypt cell proliferation and expansion of the mucosal epithelium in the small bowel of mice and rats. He subsequently identified and characterized a DPP-4-resistant molecule, teduglutide, that was ultimately developed and approved for the treatment of short bowel syndrome in adults and children, a disorder in which fluids are poorly absorbed after resection of the small intestine.
Sources: en.wikipedia.org
== Weapons == Someone hit by a shotgun will not fly backwards like it is often portrayed in movies, and the same is true for other handheld weapons. The momentum of the bullet is no higher than the recoil transmitted to the shooter, which is too little to cause any significant motion. Land mines explode immediately when stepped on. They are not armed when stepped on and then triggered by stepping off, as depicted in fictional portrayals where disarming the mine is a source of narrative.
== Etymology == The term is derived from integumentum, which is Latin for "a covering". In a transferred, or figurative sense, it could mean a cloak or a disguise. In English, "integument" is a fairly modern word, its origin having been traced back to the early seventeenth century; and refers to a material or layer with which anything is enclosed, clothed, or covered in the sense of "clad" or "coated", as with a skin or husk.
In the case of Cu3(BTC)2 the morphology of the solvent free synthesised product was the same as the industrially made Basolite C300. It is thought that localised melting of the components due to the high collision energy in the ball mill may assist the reaction. The formation of acetic acid as a by-product in the reactions in the ball mill may also help in the reaction having a solvent effect in the ball mill. It has been shown that the addition of small quantities of ethanol for the mechanochemical synthesis of Cu3(BTC)2 significantly reduces the amounts of structural defects in the obtained material. A recent advancement in the solvent-free preparation of MOF films and composites is their synthesis by chemical vapor deposition. This process, MOF-CVD, was first demonstrated for ZIF-8 and consists of two steps. In a first step, metal oxide precursor layers are deposited. In the second step, these precursor layers are exposed to sublimed ligand molecules, that induce a phase transformation to the MOF crystal lattice. Formation of water during this reaction plays a crucial role in directing the transformation. This process was successfully scaled up to an integrated cleanroom process, conforming to industrial microfabrication standards. Numerous methods have been reported for the growth of MOFs as oriented thin films. However, these methods are suitable only for the synthesis of a small number of MOF topologies. One such example being the vapor-assisted conversion (VAC) which can be used for the thin film synthesis of several UiO-type MOFs.
Many species have so-called sex chromosomes that determine the sex of each organism. In humans and many other animals, the Y chromosome contains the gene that triggers the development of the specifically male characteristics. In evolution, this chromosome has lost most of its content and also most of its genes, while the X chromosome is similar to the other chromosomes and contains many genes. This being said, Mary Frances Lyon discovered that there is X-chromosome inactivation during reproduction to avoid passing on twice as many genes to the offspring. Lyon's discovery led to the discovery of X-linked diseases.
== Selected-reaction monitoring chromatogram (SRM, MRM) == The selected-reaction monitoring (SRM) experiment is very similar to the SIM experiment except that tandem mass spectrometry is used and a specific product ion of a specific parent ion is detected. The mass of the parent analyte is first selected while other ions are filtered away. The parent analyte ion is then fragmented in the gas phase and a specific fragment ion is monitored. This experiment has very high specificity because the SRM chromatogram represents only ions of a particular mass that fragment in a manner that produce a very specific product mass. This type of experiment can only be performed using tandem mass spectrometry. The technology progress in the MS/MS area lead to the development of MRM, Multiple Reaction Monitoring, which allows simultaneous detection of several coeluting analytes with different parent and/or product ions.
Sources: en.wikipedia.org
Simple drying usually removes water by evaporation from a liquid or solid, often with heat. Lyophilization first freezes the material and then removes ice by sublimation under vacuum. This avoids prolonged exposure to liquid water and high temperatures.
Reduced pressure lowers the boiling point of water and allows ice to sublime at temperatures below freezing. It also helps remove water vapor from the product toward the condenser. The exact pressure is chosen to stay below the triple point of water.
No. Materials with low solids content or high volatile solvents may form weak or collapsed cakes. Some proteins and cells require stabilizers to survive freezing and drying stresses. Feasibility depends on formulation and process design.
Primary drying removes ice by sublimation under vacuum. Secondary drying removes water that is bound to the material, often by warming the product after most ice has left. Both stages occur below temperatures that would cause unwanted melting.