Water content comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-10-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonym | Freeze-drying | Same dehydration operation |
| Typical vacuum | 10-100 Pa | Pressure during primary drying |
| Primary drying temperature | -40 to -10 °C | Below collapse temperature for many formulations |
| Cycle duration | 12-72 hours | Varies with load, container, and formulation |
| Key phase change | Sublimation | Solid ice to water vapor |
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.
Handling practices aim to prevent moisture ingress and mechanical damage. Vials should remain stoppered and crimped until use, and reconstitution should follow the labeled diluent and volume. Shipping may involve temperature-controlled containers and desiccants, but direct contact between desiccant and product is avoided. Regulatory guidance expects documented storage conditions, excursion assessments, and stability commitments. Open questions remain about how best to predict long-term stability from short accelerated studies for every formulation class.
After lyophilization, the product is usually a porous cake or powder with a large internal surface area. This structure can absorb moisture quickly if exposed to humid air, so vials are sealed under vacuum or an inert gas. Moisture uptake may lower the glass transition temperature of the dried matrix and accelerate chemical or physical degradation. Storage conditions therefore depend on the formulation, container, and intended shelf life. Some products remain stable at room temperature, while others require refrigeration or freezing.
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.
Quality control for freeze-dried forms includes visual inspection, water content measurement, and reconstitution time. A satisfactory cake is typically uniform, porous, and intact, although minor shrinkage or cracking may be acceptable if specifications allow. Karl Fischer titration, thermal gravimetric analysis, and near-infrared spectroscopy are used to measure water content. Reconstitution is assessed by adding a specified diluent and recording the time and ease of dissolution. Microbiological and particulate tests are added when the product is sterile or intended for injection.
Stability of a lyophilized solid depends on water content, temperature, and the physical state of the formulation. Amorphous products may slowly absorb moisture and drop below their glass transition temperature, causing collapse or crystallization. Some proteins and peptides can aggregate even in a dry state, especially when exposed to heat or moisture. Accelerated stability studies at elevated temperature and humidity help estimate shelf life, but real-time data remain the basis for expiration dating.
After drying, a lyophilized product is usually sealed under vacuum or an inert gas to limit moisture and oxygen exposure. The container closure system matters because stoppers and seals can allow moisture ingress over time. Storage conditions are selected from stability studies that track potency, cake appearance, and reconstitution behavior. Many freeze-dried materials are kept at controlled room temperature, while some require refrigeration or protection from light.
==== Reserve ==== On 1 September 2014, 21 and 23 SAS were moved from UKSF. They were placed under command of 1st Intelligence, Surveillance and Reconnaissance Brigade. In 2019 they were moved back to UKSF.
When used during pregnancy, the majority of adverse events caused by acupuncture were mild and transient, with few serious adverse events. The most frequent mild adverse event was needling or unspecified pain, followed by bleeding. Although two deaths (one stillbirth and one neonatal death) were reported, there was a lack of acupuncture-associated maternal mortality. Limiting the evidence as certain, probable or possible in the causality evaluation, the estimated incidence of adverse events following acupuncture in pregnant women was 131 per 10,000. Although acupuncture is not contraindicated in pregnant women, some specific acupuncture points are particularly sensitive to needle insertion; these spots, as well as the abdominal region, should be avoided during pregnancy.
== Other related disorders == When sIBM was originally described, the major feature noted was muscle inflammation. Two other disorders were also known to display muscle inflammation, and sIBM was classified along with them. They are dermatomyositis (DM) and polymyositis (PM) and all three illnesses were called idiopathic (of unknown origin) myositis or inflammatory myopathies. It appears that sIBM and polymyositis share some features, especially the initial sequence of immune system activation, however, polymyositis comes on over weeks or months, does not display the subsequent muscle degeneration and protein abnormalities as seen in IBM, and as well, polymyositis tends to respond well to treatments, IBM does not. IBM is often confused with (misdiagnosed as) polymyositis. Polymyositis that does not respond to treatment is likely IBM. Dermatomyositis shares a number of similar physical symptoms and histopathological traits as polymyositis, but exhibits a skin rash not seen in polymyositis or sIBM. It may have different root causes unrelated to either polymyositis or sIBM. Mutations in valosin-containing protein (VCP) cause multisystem proteinopathy (MSP), which can present (among others) as a rare form of inclusion body myopathy.
Other functions include training of those entities with legal obligations to report information, development of laws and regulations to support national-level AML objectives, and international and regional cooperation in the development of AML typologies and countermeasures. After the Taliban regained control of the country in August 2021, FinTRACA's access to international financial intelligence data was removed. As of April 2026, access has not been re-established.
Sources: en.wikipedia.org
=== Pheu Thai Party === Pheu Thai leaders also thanked their supporters after the party placed third in the election. Former Deputy Finance Minister Julapun Amornvivat stated that Pheu Thai respected the democratic process and accepted that government formation was the responsibility of Bhumjaithai. Julapun stated that the party was ready to serve the public, whether in government or opposition. He noted that no discussions on coalition participation had taken place and would also review factors behind its lower performance following the completion of the vote count.
Albert Pinhasov (Hebrew: אלברט פנחסוב; born 9 February 1972) is the Rector of Ariel University. He is a researcher in the fields of Molecular Psychiatry and Psychopharmacology.He also served as Vice President and Dean for Research & Development and the Head of the Department of Molecular Biology at Ariel University. Albert Pinhasov was born on 9 February 1972 in the city of Namangan, Uzbekistan. From 1990 to 1994, he studied at the Gorky Academy of Medicine, in the city of Nizhny Novgorod, Russia. In 1994, he immigrated to Israel where he continued his education at Tel Aviv University. He was awarded a Master of Science degree (MSc) in 1998 and a PhD in the field of Molecular Biology and Clinical Biochemistry under the mentorship of Illana Gozes in 2002 from Tel Aviv University.
The NAD⁺-II riboswitch (also called the pnuC RNA motif) is a riboswitch found in bacteria that regulates gene expression in response to levels of nicotinamide adenine dinucleotide (NAD⁺) and related metabolites, particularly nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR). A shorter variant, the mini-NAD⁺-II riboswitch, was described in 2025 and is more phylogenetically widespread than the original class. NAD⁺ is a ubiquitous enzyme cofactor that functions as a carrier of hydride ions in metabolic oxidation-reduction reactions. It also serves as a source of activated adenosine monophosphate (AMP) for adenylation reactions and as a precursor of ADP-ribose. Because of NAD⁺'s essential role in cellular metabolism, bacteria must carefully regulate genes involved in both the de novo biosynthesis and salvage (recycling) of NAD⁺ and its many derivatives. Two classes of NAD riboswitches have been identified: NAD-I and NAD⁺-II.
Alyx Vance is a fictional character from Valve's Half-Life video game series. She is introduced as a non-playable, supporting character in Half-Life 2 (2004), accompanying the player's character, Gordon Freeman, throughout much of the game. She subsequently appears in a similar capacity in Half-Life 2: Episode One (2006) and Episode Two (2007), and as the titular protagonist of the VR game Half-Life: Alyx (2020). Alyx is portrayed as a young woman in her mid-twenties of Afro-Asian descent, and is a prominent figure in the human resistance against the rule of the alien empire called the Combine and their human representative, Dr. Wallace Breen. She is the daughter of resistance leader Dr. Eli Vance, and becomes a close friend and ally of Gordon. She received highly positive reviews from critics.
The first gene silencing approach to Alzheimer's disease is reported, with a drug called BIIB080 used on the microtubule-associated protein tau (MAPT) gene. Patients in a Phase 1 trial were found to have a greater than 50% reduction in levels of harmful tau protein after taking the drug. 26 April Astronomers present an image, for the first time viewed together, of the shadow of the black hole in the center of the Messier 87 galaxy, and its related high-energy jet. The first global assessment of glacier mass loss from satellite radar altimetry is published. It shows that glaciers lost 2,720 gigatonnes of ice, about 2% of their volume, between 2010 and 2020. 28 April – Progress in AI software: ChatGPT is shown to outperform human doctors in responding to online medical questions when measured on quality and empathy by "a team of licensed health care professionals", albeit the chatbot may have previously been trained with these reddit question and answers threads.
Sources: en.wikipedia.org
Nkrumah was the first African head of state to promote the concept of Pan-Africanism, which he had been introduced to during his studies at Lincoln University, Pennsylvania in the United States, at the time when Marcus Garvey was known for his "Back to Africa Movement". He merged the teachings of Garvey, Martin Luther King Jr. and the naturalised Ghanaian scholar W. E. B. Du Bois into the formation of 1960s Ghana. Osagyefo Dr. Kwame Nkrumah, as he became known, played a part in the founding of the Non-Aligned Movement, and in establishing the Kwame Nkrumah Ideological Institute to teach his ideologies of communism and socialism. His life achievements were recognised by Ghanaians during his centenary birthday celebration, and the day was instituted as a public holiday in Ghana (Founders' Day).
== Treatment == This applies once an infestation is established. In many circles the first response to cutaneous myiasis once the breathing hole has formed is to cover the air hole thickly with petroleum jelly. Lack of oxygen then forces the larva to the surface, where it can more easily be dealt with. In a clinical or veterinary setting there may not be time for such tentative approaches, and the treatment of choice might be more direct, with or without an incision. First, the larva must be eliminated through pressure around the lesion and the use of forceps. Secondly, the wound must be cleaned and disinfected. Further control is necessary to avoid further reinfestation. Livestock may be treated prophylactically with slow-release boluses containing ivermectin, which can provide long-term protection against the development of the larvae. Sheep also may be dipped, a process that involves drenching the animals in persistent insecticide to poison the larvae before they develop into a problem.
Humans and animals exposed to vacuum will lose consciousness after a few seconds and die of hypoxia within minutes, but the symptoms are not nearly as graphic as commonly depicted in media and popular culture. The reduction in pressure lowers the temperature at which blood and other body fluids boil, but the elastic pressure of blood vessels ensures that this boiling point remains above the internal body temperature of 37 °C. Although the blood will not boil, the formation of gas bubbles in bodily fluids at reduced pressures, known as ebullism, is still a concern. The gas may bloat the body to twice its normal size and slow circulation, but tissues are elastic and porous enough to prevent rupture. Swelling and ebullism can be restrained by containment in a pressure suit. Shuttle astronauts wore a fitted elastic garment called the Crew Altitude Protection Suit (CAPS) which prevents ebullism at pressures as low as 2 kPa (15 Torr). Rapid boiling will cool the skin and create frost, particularly in the mouth, but this is not a significant hazard. Animal experiments show that rapid and complete recovery is normal for exposures shorter than 90 seconds, while longer full-body exposures are fatal and resuscitation has never been successful. A study by NASA on eight chimpanzees found all of them survived two and a half minute exposures to vacuum. There is only a limited amount of data available from human accidents, but it is consistent with animal data. Limbs may be exposed for much longer if breathing is not impaired.
English Defence League founder Tommy Robinson is charged by police with failing to comply with an order to stay away from the previous day's antisemitism march after attending the rally. 28 November An investigation by The Guardian finds that potentially toxic "forever chemicals" are present in the drinking water sources at 17 of the 18 water companies in England. Virgin Atlantic launches the world's first transatlantic flight by a large passenger plane using 100% sustainable aviation fuel. The passengerless journey is made by a Boeing 787 travelling from London Heathrow to New York. 29 November The coldest November night since 2010 is experienced by many parts of the UK, reaching as low as −8 °C (18 °F) in Aonach Mòr in the Scottish Highlands, with snow and ice warnings for various regions extending to Friday. Natural England announces that England will be getting a new National Park. The Chilterns, The Cotswolds and Dorset could become new National Parks. Nottingham City Council declares itself effectively bankrupt, with a £23m overspend forecast for the 2023–24 financial year. At Prime Minister's Questions, Sunak accuses the Greek prime minister of trying to "grandstand" over the Elgin Marbles when questioned about his decision to cancel a planned meeting with Mitsotakis. 30 November Matt Hancock, who served as health secretary from 2018 to 2021, appears at the latest stage of the COVID-19 inquiry. RMT members vote to accept a pay deal from 14 train companies, which ends a long-running series of strikes until at least spring 2024.
== Electrospray ionization == Electrospray ionization (ESI) is a technique that involves using high voltages to create an electrospray, or a fine aerosol created by the high voltages. ESI sample preparation can be very important and the quality of results can be heavily determined by the characteristics of the sample. ESI experiments can be run on-line or off-line. In on-line measurements the mass spectrometer is connected to a liquid chromatograph and as the samples are separated they are ionized into the mass spectrometer by the ESI system; sample preparation is actually performed before the LC separation. In off-line measurements, the analyte solution is applied directly to the mass spectrometer by a spray capillary . Off-line sample preparation has many considerations, such as the fact that the capillary used allows for the application of volumes in the nanoliter range, which can contain a concentration too small for analysis of many compounds, such as proteins. An additional problem can be loss of ESI signal due to interference between the analyte sample and background components. Unfortunately, it has been shown that sample preparation itself can only slightly alleviate this problem which is due more to the nature of the analyte itself than the preparation. In ESI the principal problem comes not from reactions in the gas phase but rather from problems involving the solution phase of the droplets themselves.
Sources: en.wikipedia.org
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.
Sublimation requires the solvent to remain solid so vapor leaves without passing through a liquid phase. If the product melts, the porous structure can collapse and drying becomes uneven. Maintaining frozen conditions preserves the intended physical form.
No, freeze-drying is a dehydration method, not a sterilization step. It can reduce water activity and limit microbial growth during storage, but it does not reliably kill microbes or remove endotoxins. Sterility must come from separate validated processes.
Many dried cakes are hygroscopic and can adsorb water during storage or handling. Absorbed moisture may lower the glass transition temperature and promote chemical reactions. Sealed packaging and controlled humidity reduce this risk.