lyophilization raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-11-02. Anything still debated is marked as such rather than presented as settled.
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 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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilization is the American spelling; lyophilisation is British |
| Primary drying mechanism | Sublimation of ice | Occurs under vacuum below the triple point |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product and equipment |
| Typical shelf temperature during freezing | -40 to -20 °C | Lower temperatures may be used for labile products |
| Resulting product form | Porous cake or powder | Appearance depends on formulation and cycle |
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.
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.
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.
Isotretinoin is a teratogen highly likely to cause birth defects if taken by women during pregnancy or even a short time before conception. A few of the more common birth defects this drug can cause are hearing and visual impairment, missing or malformed earlobes, facial dysmorphism, and abnormalities in brain function. Isotretinoin is classified as FDA Pregnancy Category X and ADEC Category X, and use is contraindicated in pregnancy. In the EU, isotretinoin (oral) is contraindicated in pregnancy and must not be taken by women able to have children unless the conditions of a pregnancy prevention program are met. The manufacturer recommends pregnancy be ruled out two weeks before commencement of isotretinoin, and women should use two simultaneous forms of effective contraception at least one month before commencement, during, and for at least one month following isotretinoin therapy. In the US, around 2000 women became pregnant while taking the drug between 1982 and 2000, with most pregnancies ending in abortion or miscarriage. About 160 babies with birth defects were born. After the FDA put the more strict iPLEDGE program in place for the companies marketing the drug in the US, in 2011, 155 pregnancies occurred (0.12%) among 129,544 women of childbearing potential taking isotretinoin. People taking isotretinoin are advised against donating blood during and for at least one month after treatment due to its teratogenicity.
Sensation: The oral mucosa is richly innervated, meaning it is a very good at sensing pain, touch, temperature and taste. A number of cranial nerves are involved in sensations in the mouth including trigeminal (V), facial (VII), glossopharyngeal (IX) and vagus (X) nerves. The dorsum of the tongue is covered in specialised mucosa. This contains the presence of taste buds allowing taste, and it accounts for around 15% of oral mucosa. Reflexes such as swallowing, gagging and thirst are also initiated in the mouth. Thermal regulation: Although not significant in humans, some animals such as dogs rely on panting to regulate their temperature, as sweat glands are only present in their paws.
==== Lifestyle ==== Physical activity can reduce the risk of cardiovascular disease, and people at risk are advised to engage in 150 minutes of moderate or 75 minutes of vigorous intensity aerobic exercise a week. Keeping a healthy weight, drinking alcohol within the recommended limits, and quitting smoking reduce the risk of cardiovascular disease. Substituting unsaturated fats such as olive oil and rapeseed oil instead of saturated fats may reduce the risk of myocardial infarction, although there is not universal agreement. Dietary modifications are recommended by some national authorities, with recommendations including increasing the intake of wholegrain starch, reducing sugar intake (particularly of refined sugar), consuming five portions of fruit and vegetables daily, consuming two or more portions of fish per week, and consuming 4–5 portions of unsalted nuts, seeds, or legumes per week. The dietary pattern with the greatest support is the Mediterranean diet. Vitamins and mineral supplements are of no proven benefit, and neither are plant stanols or sterols. Public health measures may also act at a population level to reduce the risk of myocardial infarction, for example by reducing unhealthy diets (excessive salt, saturated fat, and trans-fat) including food labeling and marketing requirements as well as requirements for catering and restaurants and stimulating physical activity. This may be part of regional cardiovascular disease prevention programs or through the health impact assessment of regional and local plans and policies.
On 29 January 2015, after the defeat of the Iraq national football team and the United Arab Emirates national football team during the 2015 AFC Asian Cup, West Asian Football Federation members reportedly sought to remove Australia from the AFC, primarily due to "Australia benefiting hugely from Asian involvement without giving much in return". In November 2018, with numerous FFA directors ending their 3-year term, the bulk were replaced at the annual general meeting. Steven Lowy resigned as chair of the directors in protest at major changes to the governance and voting structure in the Football Australia Congress which elects the directors. His position was filled by Chris Nikou. On 25 June 2020, FFA won the rights to co-host the 2023 FIFA Women's World Cup alongside New Zealand. On 25 November 2020, the FFA, in annual general meeting, voted to rename itself to Football Australia (FA) (following the end of the rival Football Australia competition, which had been formed in 2012). The name change was seen as a way to align branding with the state member federations. On 31 December 2020, FA announced that the A-League, W-League and Y-League would no longer be operated by it in an 'unbundling' (de-merger or spinoff) process. The newly formed commercial Australian Professional Leagues would take over the running of the premier soccer competitions. As part of the unbundling, the Australian Professional Leagues also obtained the exclusive right to use the intellectual property rights associated with the A-League brand.
Sources: en.wikipedia.org
358 employees from Marsh Inc., located immediately below Cantor Fitzgerald on floors 93–100, died. 176 employees from Aon Corporation died. The National Institute of Standards and Technology (NIST) estimated that about 17,400 civilians were in the World Trade Center complex at the time of the attacks. Turnstile counts from the Port Authority suggest 14,154 people were typically in the Twin Towers by 8:45 a.m. Most people below the impact zone safely evacuated. In Arlington County, Virginia, 125 Pentagon workers died when Flight 77 crashed into the building's western side. Seventy were civilians and 55 were military personnel, many of whom worked for the United States Army or the United States Navy. 47 civilian employees, six civilian contractors, and 22 soldiers working for the Army died, while six civilian employees, three civilian contractors, and 33 sailors working for the Navy died. Seven Defense Intelligence Agency (DIA) civilian employees and one Office of the Secretary of Defense contractor died. Timothy Maude, a Lieutenant General and Army Deputy Chief of Staff, was the highest-ranking military official killed at the Pentagon. Weeks after the attack, the death toll was estimated to be over 6,000, more than twice the number of deaths eventually confirmed. The city was only able to identify remains for about 1,600 of the World Trade Center victims.
The predicted half-lives for these nuclides often greatly exceed the estimated age of the universe, and in fact, there are also 31 known radionuclides (see primordial nuclide) with half-lives longer than the age of the universe. The total of all known nuclides, of which most have been created only artificially, is several thousand, of which 987 are stable or have a half-life longer than one hour; see List of nuclides.
=== Expansion and diversification === In 1975, UPS moved its headquarters to Greenwich, Connecticut, and began serving all of the 48 contiguous states of the United States. This expansion of operations made UPS the first package delivery company to serve every address in the contiguous United States. Additionally in 1975, UPS went international by establishing operations in Canada. In 1976, UPS established a domestic operation in West Germany. UPS Next Day Air Service was launched in 1985 for all 48 contiguous states plus Puerto Rico. In 1988, UPS Airlines was launched with authorization from the Federal Aviation Administration and became the fastest-growing airline in FAA history – currently the 10th largest airline in the United States. Domestic air service was added to Germany in 1989. In 1991, UPS relocated its headquarters to Sandy Springs, Georgia, a suburb of Atlanta. Following this in 1992, UPS acquired both Haulfast and Carryfast and rebranded them into UPS Supply Chain Solutions. Haulfast provided the pallet haulage and trucking network for the CarryFast group of companies. By 1993, UPS was delivering up to 11.5 million packages and documents per day. In order for the company to service the large volume of customers in 1991, UPS developed technologies to improve efficiency. A handheld device named the "Delivery Information Acquisition Device" (DIAD) was created to record and upload delivery information to the UPS network immediately upon pickup by every UPS driver. In 1992, UPS began tracking all ground shipments electronically.
This relative stability was consolidated with the oil expropriation carried out in 1938, which universally raised Cárdenas' popularity. The United States, seeing Mexico's stability, decided not to retaliate following the expropriation and reached a compensation agreement as part of the Good Neighbor policy, which would help establish post-war Pan-American cooperation.
Crocodile oil is extracted from the fatty tissues of crocodiles. Crocodile fat is a product of commercial farming, evident in Thailand. Historically, for centuries crocodile oil has been used by traditional practitioners across the globe, including Chinese traditional medicine, Southeast Asia, Ancient Egypt. Crocodile oil has been used since the nineteenth century for different purposes in different cultures. Due to the oil's components, its richness in monounsaturated and polyunsaturated fats, it is sold as ointment for treatment of skin conditions, skin structure enhancement, collagen deposition, and medicine for illnesses. In recent times, the use of crocodile oil has invited criticism from the use of crocodile oil as there is an increased demand for cruelty-free and vegan-friendly beauty products in consumers of today's society.
Sources: en.wikipedia.org
=== Terminology === The term "wet market" came into common use in Singapore in the early 1970s when the government used it to distinguish such traditional markets from the supermarkets that had become popular there. The term was added to the Oxford English Dictionary (OED) in 2016, as a term used throughout Southeast Asia. The OED's earliest cited use of the term is from The Straits Times of Singapore in 1978. The term did not originate in mainland China. No Chinese name for these markets refers to wetness: in mainland China they are officially called nongmao shichang (农贸市场, "farmers' market") or cai shichang (菜市场, "produce market") and colloquially caichang (菜场), while in Hong Kong Cantonese they are jieshi (街市, "street market"). The "wet" in "wet market" refers to the constantly wet floors due to the melting of ice used to keep food from spoiling, the washing of meat and seafood stalls and the spraying of fresh produce that is common in these markets. The term "public market" may be synonymous with "wet market", although it may sometimes refer exclusively to state-owned and community-owned markets. These markets may also be called "fresh food markets" and "good food markets" when referring to markets consisting of numerous competing vendors primarily selling fresh produce like fruits and vegetables. The term "wet market" is frequently used to signify a live animal market that sells directly to consumers, although the terms are not synonymous.
== Recognition == 2022 – IDLO was included in the Forbes Next 250 list. The company reported UAH 32 million in sales. 2023 – IDLO received the ISPO Award, an international prize in the outdoor and sports gear industry. 2024 – The compan received the “Tested in Antarctica” mark from the National Antarctic Scientific Center of Ukraine. This distinction recognizes national manufacturers whose products have successfully endured Antarctic conditions. IDLO was the first company to receive this mark, acknowledging its long-term collaboration with the Academician Vernadsky station.
== Epidemiology == Hypoglycemia is common in people with type 1 diabetes, and in people with type 2 diabetes taking insulin, glinides, or sulfonylurea. It is estimated that type 1 diabetics experience two mild, symptomatic episodes of hypoglycemia per week. Additionally, people with type 1 diabetes have at least one severe hypoglyemic episode per year, requiring treatment assistance. In terms of mortality, hypoglycemia causes death in 6–10% of type 1 diabetics. In those with type 2 diabetes, hypoglycemia is less common compared to type 1 diabetics, because medications that treat type 2 diabetes like metformin, glitazones, alpha-glucosidase inhibitors, glucagon-like peptide 1 agonists, and dipeptidyl peptidase IV inhibitors, do not cause hypoglycemia. Hypoglycemia is common in type 2 diabetics who take insulin, glinides, or sulfonylurea. Insulin use remains a key risk factor in developing hypoglycemia, regardless of diabetes type.
(WINNER) The contestant won the whole competition. (WIN) The contestant won the Haunted Heat (HIGH) The contestant had one of the best dishes in the Haunted Heat. (IN) The contestant performed well enough to move on to the next week. (RISK) The contestant had one of the bottom dishes in the Haunted Heat and competed in the Bake for Your Life challenge, but was not eliminated. (LOW) The contestant had one of the bottom dishes in the episode's only challenge but was not eliminated. (OUT) The contestant was eliminated for worst dish. (WDR) The contestant withdrew from the competition.
Sources: en.wikipedia.org
Lyophilization removes water by sublimation from a frozen material, while evaporation changes liquid water into vapor. The low-pressure freezing step avoids the liquid phase and can preserve heat-sensitive structures.
Vacuum lowers the pressure below the triple point of water, allowing ice to sublimate directly into vapor. It also helps remove water vapor from the product chamber and shortens primary drying.
Many aqueous solutions and suspensions can be freeze-dried, but some formulations collapse or do not form a stable cake. The process requires careful formulation and cycle development.
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.