Everything below concerns sublimation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-08-11. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Physical state | Solid, porous cake or powder | Depends on formulation and container |
| Typical storage temperature | 2–25 °C, protected from moisture | Some materials require colder conditions |
| Solubility class | Usually readily soluble after reconstitution | Not an intrinsic chemical property |
| Common analytical method | Karl Fischer titration | Used for residual moisture |
| Common synonyms | Freeze-drying; lyophilisation | Lyophilisation is a spelling variant |
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.
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.
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.
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 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.
=== Contaminants === Common chlorothalonil synthesis procedures frequently result in contamination of it with small amounts of hexachlorobenzene (HCB), which is toxic. US regulations limit HCB in commercial production to 0.05% of chlorothalonil. According to the EPA report, "post-application exposure to HCB from chlorothalonil is not expected to be a concern based on the low level of HCB in chlorothalonil. 2,3,7,8-Tetrachlorodibenzodioxin being one of the most potent carcinogens known is also a known contaminant".
In March 1866, a month after the fall, Eddy and her husband (then married for 13 years) moved into an unfurnished room in Lynn. At some point her husband left and Eddy was evicted, unable to pay the $1.50 weekly rent. He appears to have returned briefly—they moved to a boarding house in July, and in August he paid Dr. Cushing's bill from the fall—but the marriage was over. He sent her $200 a year for a time, and they divorced in 1873. Her first student was Hiram Crafts, a shoe worker in whose house she stayed, who advertised for patients himself in May 1867, offering a cure for "Consumption, Catarrh, Scrofula, Dyspepsia and Rheumatism." Eddy asked Crafts to set up a practice with her, but the plan came to nothing. In addition to teaching, Eddy had started to write; toward the end of 1866 she began work on an allegorical interpretation of Genesis, intended as the first volume of a book (never published), The Bible in its Spiritual Meaning. In the summer of 1868, while lodging with spiritualist Sarah Bagley in Amesbury, Eddy advertised for students in a Spiritualist magazine, the Banner of Light, as Mary B. Glover (her first husband's surname). The ad promised a "principle of science" that would heal with "[n]o medicine, electricity, physiology or hygiene required for unparalleled success in the most difficult cases". Sally Wentworth, another Spiritualist, offered Eddy $300-worth of bed and board in Stoughton if Eddy would treat her daughter's lung condition and teach Wentworth the healing method.
In April 2023, President Lula began his four-day trip during which he called Portugal relations with Brazil "extraordinary" and stated that "Portugal is not simply a foreign country but our home extension". In the 13th Brazil-Portugal Summit the countries signed several agreements such as a mutual recognition of professional degrees, driver's licenses, rights of persons with disabilities and a witness protection programme in both countries. Other agreements signed during the visit include education, science, tourism, energy and audiovisual areas. Lula also attended a high-level Brazilian-Portuguese business meeting in Matosinhos in which Brazilian aerospace giant Embraer and four Portuguese companies (OGMA, EMPORDEF, GMVIS Skysof and CEiiA) announced a deal to build a Brazilian-designed aircraft. Also in the meeting, Prime Minister António Costa announced Portugal companies EDP and Galp will be investing a total of €5.7 billion in projects in Brazil over the next years. On 24 April, Lula took part in a ceremony at the Queluz Palace to award Brazilian singer and songwriter Chico Buarque the Camões Prize.
=== Phase unknown === AP-002 (AP002) – undefined mechanism of action – opioid-related disorders AP-005 (AP005) – undefined mechanism of action – opioid-related disorders Varenicline implant (SK-2109) – nicotinic acetylcholine receptor agonist – smoking withrawal
The main natural sources of muscimol are fungi of the genus Amanita, such as Amanita muscaria (fly agaric) and Amanita pantherina (panther cap). It is produced in the mushrooms along with muscarine (which is present in trace amounts and it is not active), muscazone, and ibotenic acid. In Amanita muscaria, the layer just below the skin of the cap contains the highest amount of muscimol, and is therefore the most psychoactive portion.
Sources: en.wikipedia.org
=== Nucleobase classification === The nucleobases are classified into two types: the purines, A and G, which are fused five- and six-membered heterocyclic compounds, and the pyrimidines, the six-membered rings C and T. A fifth pyrimidine nucleobase, uracil (U), usually takes the place of thymine in RNA and differs from thymine by lacking a methyl group on its ring. In addition to RNA and DNA, many artificial nucleic acid analogues have been created to study the properties of nucleic acids, or for use in biotechnology.
Many forms of human-derived agriculture fit the broad definition of "utilizing a biotechnological system to make products". The cultivation of plants may be viewed as the earliest biotechnological enterprise. Agriculture has been theorized to have become the dominant way of producing food since the Neolithic Revolution. Through early biotechnology, the earliest farmers selected and bred the best-suited crops (e.g., those with the highest yields) to produce enough food to support a growing population. As crops and fields became increasingly large and difficult to maintain, it was discovered that specific organisms and their by-products could effectively fertilize, restore nitrogen, and control pests. Throughout the history of agriculture, farmers have inadvertently altered the genetics of their crops through introducing them to new environments and breeding them with other plants — one of the first forms of biotechnology. These processes were also included in the early fermentation of beer. These processes were introduced in early Mesopotamia, Egypt, China and India, and still use the same basic biological methods. In brewing, malted grains (containing enzymes) convert starch from grains into sugar and then adding specific yeasts to produce beer. In this process, carbohydrates in the grains broke down into alcohols, such as ethanol. Later, other cultures developed the process of lactic acid fermentation, which produced other preserved foods, such as soy sauce. Fermentation was also used in this time period to produce leavened bread.
James William Middleton (born 15 April 1987) is a British entrepreneur who is the younger brother of Catherine, Princess of Wales. Born in Reading, Berkshire, Middleton was educated at St Andrew's School, Pangbourne. He briefly attended the University of Edinburgh before dropping out and founding a cake-making business. Middleton began receiving media attention during his eldest sister's relationship with and subsequent marriage to Prince William. He is a mental health advocate and has spoken about his experiences with major depressive disorder. Middleton is also an ambassador for the Pets As Therapy charity.
Fluspirilene (Redeptin, Imap, R6218) is a diphenylbutylpiperidine typical antipsychotic drug, used for the treatment of schizophrenia. It is administered intramuscularly. It was discovered at Janssen Pharmaceutica in 1963. A 2007 systematic review investigated the efficacy of fluspirilene decanoate for people with schizophrenia:
Sources: en.wikipedia.org
Freezing only converts liquid to solid. Lyophilization adds vacuum and controlled warming so frozen solvent sublimes, leaving a dry porous solid. The two steps are related but not interchangeable.
Reduced pressure keeps the solvent below its triple point, allowing ice to become vapor without melting. Vacuum also helps remove water vapor from the product chamber. The exact pressure is chosen with the formulation and equipment.
Residual moisture is water that remains in the dried solid after secondary drying. It is often measured by Karl Fischer titration, near-infrared spectroscopy, or thermogravimetry. Acceptable levels depend on the material and its stability profile.
Yes, the terms are generally interchangeable. Lyophilization is more common in pharmaceutical and laboratory contexts, while freeze-drying appears widely in food science and general writing. Both describe removal of solvent by sublimation under vacuum after freezing.