Everything below concerns freeze-drying. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
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 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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilisation is the British spelling; the process is not simple evaporation. |
| Primary drying pressure | 0.05–0.3 mbar | Pressure must remain below the vapor pressure of ice at the product temperature. |
| Sublimation temperature | Below 0 °C | Ice changes directly to vapor while the product remains frozen. |
| Typical shelf temperature | −40 to −10 °C | Exact setting depends on formulation critical temperature and equipment. |
| Cycle duration | 12–72 hours | Time varies with fill volume, formulation, and dryer performance. |
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.
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.
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.
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, 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.
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.
== Teaching using simulator == User comments about AIDA have highlighted some of the many ways in which people have applied the simulations in their own particular situations. A great deal of attention has focused, understandably, on use by individuals with diabetes and their relatives, as well as by health-care professionals such as diabetologists / endocrinologists and diabetes educators. However, an important group of health-carers involved in the provision of day-today care for many people with diabetes are primary care physicians (general practitioners [GPs]). A workshop was held in September 2000 in Italy — by an independent diabetologist / endocrinologist unconnected with the AIDA simulator's development — to gain experience with application of the AIDA diabetes simulation approach as a teaching tool for general practitioners (GPs). Feedback obtained from participants attending the workshop was very positive, with GPs reporting the simulation approach to be both of interest and use. Another important group of health-carers involved in the provision of day-to-day care for many people with diabetes are nurses. A separate workshop was held in June 2001 in Italy — by the same independent diabetologist / endocrinologist — to gain experience with application of the AIDA diabetes simulation approach as a teaching tool for student nurses. Feedback obtained from participants attending the workshop was generally very positive, with the student nurses also reporting the simulation approach to be both of interest and of use.
=== 2006: University of Melbourne affiliation === In 2006 the VCA became an affiliated college of the University of Melbourne, and on 1 January 2007 the VCA became known as the Faculty of the Victorian College of the Arts, University of Melbourne. In April 2009 the school became part of the new Faculty of the VCA and Music (VCAM). The School of Music was amalgamated with the University of Melbourne's Faculty of Music and the VCA Secondary School was separated and given a new campus.
glutathione + formaldehyde This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is S-(hydroxymethyl)glutathione formaldehyde-lyase (glutathione-forming). Other names in common use include glutathione-dependent formaldehyde-activating enzyme, Gfa, and S-(hydroxymethyl)glutathione formaldehyde-lyase. This enzyme participates in methane metabolism.
== Limitations == Chemotherapy does not always work, and even when it is useful, it may not completely destroy the cancer. People frequently fail to understand its limitations. In one study of people who had been newly diagnosed with incurable, stage 4 cancer, more than two-thirds of people with lung cancer and more than four-fifths of people with colorectal cancer still believed that chemotherapy was likely to cure their cancer. The blood–brain barrier poses an obstacle to delivery of chemotherapy to the brain. This is because the brain has an extensive system in place to protect it from harmful chemicals. Drug transporters can pump out drugs from the brain and brain's blood vessel cells into the cerebrospinal fluid and blood circulation. These transporters pump out most chemotherapy drugs, which reduces their efficacy for treatment of brain tumors. Only small lipophilic alkylating agents such as lomustine or temozolomide are able to cross this blood–brain barrier. Blood vessels in tumors are very different from those seen in normal tissues. As a tumor grows, tumor cells furthest away from the blood vessels become low in oxygen (hypoxic). To counteract this they then signal for new blood vessels to grow. The newly formed tumor vasculature is poorly formed and does not deliver an adequate blood supply to all areas of the tumor. This leads to issues with drug delivery because many drugs will be delivered to the tumor by the circulatory system.
Sources: en.wikipedia.org
== History == The company was founded in 1929 by Dharampal Sugandhi in Chandni Chowk, Delhi, as a perfumery business producing incense sticks, rose water, and tobacco products. In 1958, Satyapal Sugandhi introduced the BABA tobacco brand. During the 1980s, the group diversified into packaged foods with the launch of Catch Salt & Pepper (1987), followed by Catch Natural Spring Water in 1999. The group's subsequent launches included confectionery products under brands such as Rajnigandha, Pass Pass, and Pulse Candy. In 2019, the DS Group acquired an 11–18% stake in the Switzerland-based Lalique Group . In 2023, it introduced the Swiss chocolate brand Läderach to India and acquired the Indian confectionery brand LuvIt.
However, the eras of the two empires also witnessed a steady erosion of women's rights, and, by the end, the institutionalisation of untouchability. In South India, the Sangam literature of the Tamil language reveals that, between 200 BCE and 200 CE, the southern peninsula was ruled by the Cheras and the Cholas, along the western and eastern plains, respectively, of the Kaveri river valley, and the Pandyas farther south along the Vaigai river valley. By the sixth century, the Pallavas had grown into a regional power. Simultaneously, Buddhism and Jainism, which had favoured a conservative transactionalism, were replaced by kingly devotion to the gods of particular places, which became a characteristic of the Bhakti movement. The Pallavas, in particular, traded extensively with the Roman Empire and with West and Southeast Asia.
== Career == On 18 July 1985, he co-founded the Belgian biotech company Innogenetics, together with Erik Tambuyzer and Hugo Van Heuverswyn and has been its chairman since then. Besides Innogenetics, he founded several clinical laboratories. He is an international centralized clinical laboratory. He is also CEO of Gengest BVBA (management company), Biovest CVA, LMA BVBA, Laboraco BVBA, and he is director of DSJ Bruxelles NV and Oystershell NV. Rudi Mariën is a member of the American Association for Clinical Chemistry.
The non-dominant epitope could generate a stronger immune response than the dominant epitope. Ex. The antibodies from people infected by hookworm can recognize the dominant epitope of the antigen called Necator americanus APR-1 protein, but the antibodies can't induce protection against hookworm. However, other non-dominant epitopes on APR-1 protein show the ability to induce the production of neutralizing antibodies against hookworm. Therefore, the non-dominant epitopes are the better candidate for peptide vaccines against hookworm infection. Take hypersensitivity into consideration. Ex. Some IgE-inducing epitopes cause hypersensitivity reactions after vaccination in humans due to the overlap with IgG epitopes in the Na-ASP-2 protein which is an antigen from hookworm. Some short peptide epitopes need elongating to maintain the native conformation. The elongated sequences can include proper secondary structure. Also, some short peptides can be stabled or cyclized together to maintain the proper conformation. Ex. B-cell epitopes could only have 5 amino acids. To induce an immune response, a sequence from yeast GCN4 protein is used to improve the conformation of the peptide vaccines by forming alpha-helix. Use adjuvants associated with the epitope to induce the immune response.
== Principle of the method == ZooMS identifies species based on differences in the amino acid composition of the collagen protein. The amino acid sequence of a species' collagen protein is determined by its DNA and as a result like DNA, the amino acid sequence reflects a species' evolutionary history. The greater the evolutionary distance between two species, the more different their collagen proteins will be. ZooMS typically can identify a sample up to genus level, though in some cases the identification can be more or less specific. A good understanding of the archaeological context of the sample can be used to further refine the resolution of the species identification.
Sources: en.wikipedia.org
An antihemorrhagic (British English: antihaemorrhagic) agent is a substance that promotes hemostasis (a process which stops bleeding). It may also be known as a hemostatic (also spelled haemostatic) agent. Antihemorrhagic agents used in medicine have various mechanisms of action:
Removes the hair and other keratinous matter Removes some of the interfibrillary soluble proteins such as mucins Causes the fibers to swell up and split up to the desired extent Removes the natural grease and fats to some extent Brings the collagen in the hide to a proper condition for satisfactory tannage The weakening of hair is dependent on the breakdown of the disulfide link of the amino acid cystine, which is the characteristic of the keratin class of proteins that gives strength to hair and wools (keratin typically makes up 90% of the dry weight of hair). The hydrogen atoms supplied by the sharpening agent weaken the cystine molecular link whereby the covalent disulfide bond links are ultimately ruptured, weakening the keratin. To some extent, sharpening also contributes to unhairing, as it tends to break down the hair proteins. The isoelectric point of the collagen (a tissue-strengthening protein unrelated to keratin) in the hide is also shifted to around pH 4.7 due to liming.
== Simulating wound healing from a growth perspective == Considerable effort has been devoted to understanding the physical relationships governing wound healing and subsequent scarring, with mathematical models and simulations developed to elucidate these relationships. The growth of tissue around the wound site is a result of the migration of cells and collagen deposition by these cells. The alignment of collagen describes the degree of scarring; basket-weave orientation of collagen is characteristic of normal skin, whereas aligned collagen fibers lead to significant scarring. It has been shown that the growth of tissue and extent of scar formation can be controlled by modulating the stress at a wound site. The growth of tissue can be simulated using the aforementioned relationships from a biochemical and biomechanical point of view. The biologically active chemicals that play an important role in wound healing are modeled with Fickian diffusion to generate concentration profiles. The balance equation for open systems when modeling wound healing incorporates mass growth due to cell migration and proliferation. Here the following equation is used: Dtρ0 = Div (R) + R0, where ρ represents mass density, R represents a mass flux (from cell migration), and R0 represents a mass source (from cell proliferation, division, or enlargement). Relationships like these can be incorporated into an agent-based models, where the sensitivity to single parameters such as initial collagen alignment, cytokine properties, and cell proliferation rates can be tested.
==== Effect on differentiation ==== ECM elasticity can direct cellular differentiation, the process by which a cell changes from one cell type to another. In particular, naive mesenchymal stem cells (MSCs) have been shown to specify lineage and commit to phenotypes with extreme sensitivity to tissue-level elasticity. MSCs placed on soft matrices that mimic the brain differentiate into neuron-like cells, showing similar shape, RNAi profiles, cytoskeletal markers, and transcription factor levels. Similarly stiffer matrices that mimic muscle are myogenic, and matrices with stiffnesses that mimic collagenous bone are osteogenic.
Sources: en.wikipedia.org
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.
Freezing determines ice crystal size, solute distribution, and the pore network left after drying. A slow or fast freezing rate can produce different cake structures and affect reconstitution. It also sets whether the formulation follows an amorphous or crystalline drying path.
It removes most free water during primary drying and part of the bound water during secondary drying. A small residual moisture content often remains and is specified for each product. Complete removal is generally neither practical nor desirable for stability.
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.