Everything below concerns Moisture sorption. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-11. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Storage conditions for dried products usually aim to exclude moisture and oxygen. Vials are sealed under vacuum or with an inert gas, and stoppers must maintain a barrier during transport. Temperature recommendations vary; some materials remain stable at room temperature, while others need refrigeration or frozen storage. Humidity control is critical because dried cakes can absorb water rapidly once a container is opened. Desiccant packs and moisture-barrier bags add further protection during shipping.
Quality control also examines cake structure, color, and reconstitution behavior. A collapsed or shrunken cake can indicate a thermal excursion during drying. Analytical methods such as X-ray diffraction, differential scanning calorimetry, and near-infrared spectroscopy can detect crystallinity or moisture distribution. Regulatory expectations focus on validated assays and lot-to-lot consistency. Questions remain about how well accelerated stability tests predict long-term behavior for every formulation. Visual inspection remains common but is subjective without trained reviewers and reference images.
After lyophilization, a product's quality depends on residual moisture, cake appearance, and reconstitution time. Residual moisture is often measured by Karl Fischer titration or thermogravimetric analysis. A low moisture content can slow chemical degradation, but overly dry cakes may be brittle or slow to dissolve. Stability studies track these attributes over months under defined temperature and humidity conditions. Batch records link these measurements to specific process runs and help identify trends before a product fails specification.
| Property | Value | Notes |
|---|---|---|
| Common name | Freeze-drying | Process removes water by sublimation under vacuum. |
| Typical primary drying shelf temperature | -40 C to -10 C | Set below the formulation's collapse temperature. |
| Typical chamber pressure | 0.05-0.3 mbar | Low pressure allows ice to sublime below its triple point. |
| Water content after drying | 0.5-3% by weight | Higher values may reduce storage stability for some materials. |
| Key thermal parameter | Collapse temperature | Measured by freeze-drying microscopy or differential scanning calorimetry. |
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.
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.
Analytical methods for lyophilized materials include X-ray diffraction for crystallinity, differential scanning calorimetry for thermal transitions, and scanning electron microscopy for pore morphology. Moisture sorption analysis shows how the cake responds to humidity. These methods help distinguish amorphous from crystalline states and detect phase changes. Open questions remain about how pore structure changes during long-term storage and how best to predict collapse under varied conditions. Comparisons across studies are complicated by differences in formulation, cycle, and storage history.
Quality control for lyophilized products focuses on appearance, moisture level, reconstitution time, and structural integrity. A cake should be uniform, intact, and free of meltback or collapse. Moisture level is measured by Karl Fischer titration or thermogravimetric analysis. Reconstitution time reflects pore structure and formulation. Visual inspection and vial integrity checks detect cracks, stopper defects, or particulate matter. These checks are often performed on samples from each batch. They help confirm that the drying cycle performed as intended.
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.
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.
Quality control for lyophilized products includes appearance, cake structure, reconstitution time, pH, residual moisture, and potency. Residual moisture is a key attribute because excess water can reduce stability, while excessively low moisture may cause structural changes or aggregation in some systems. Stability studies compare real-time and accelerated conditions to estimate shelf life. Analytical methods must be validated for the specific matrix, container, and moisture range. Sterility and container integrity are also monitored for sterile products.
=== Non-pharmacological alternatives === Weight loss effects of water have been subject to some scientific research as a potential non-pharmacological approach. Drinking water prior to each meal may help in appetite suppression. Consumption of 500 mL (18 imp fl oz; 17 US fl oz) of water 30 minutes before meals has been correlated with modest weight loss (1–2 kg; 2.2–4.4 lb) in obese men and women over a period of 8 to 12 weeks.
=== Harris's loss === Harris's loss to Trump received substantial media analysis in the aftermath of the election. Proposed explanations for the outcome of the race included inflation, the immigration crisis, a global incumbency backlash, Biden's late exit from the race, and the lack of an open Democratic primary process. Democrats and others argued about what went wrong and how the party should move forward.
UNICEF spokesperson Toby Fricker stated, "There is no safe place for children anywhere across the strip right now." On 19 December, the United Nations stated Gaza was "by far the most dangerous place in the world to be a child". James Elder, a UNICEF spokesperson, called the conflict in Gaza a "war on children." On 6 January 2024, Tanya Haj-Hassan, a doctor with Doctors Without Borders, stated children in Gaza were "dying in every way possible." On 18 January 2024, the deputy executive director of UNICEF stated the suffering of children in Gaza were the "most horrific conditions I have ever seen." On 2 February 2024, the UNICEF chair stated, "The situation for children in Gaza grows bleaker every day. The world cannot abandon them." On 5 March, UNICEF called the war on Gaza "a test of human conscience" and stated that the lack of humanitarian aid in the north was worsening children's health situation. Adele Khodr, UNICEF's Middle East regional director, stated on 19 March: "The world’s inaction is shocking as more children succumb to a slow death."
=== Muscle and connective tissue development disorders === Loss of muscle mass with an imbalance of muscle power at the joint can lead to connective tissue abnormality. This leads to joint fixation and reduced fetal movement. Also muscle abnormalities could lead to a reduction of fetal movement. Those could be: dystrophy, myopathy and mitochondrial disorders. This is mostly the result of abnormal function of the dystrophin-glycoprotein-associated complex in the sarcolemma of skeletal muscles.
Sources: en.wikipedia.org
What is the strength of the component as a function of crack size? What crack size can be tolerated under service loading, i.e. what is the maximum permissible crack size? How long does it take for a crack to grow from a certain initial size, for example the minimum detectable crack size, to the maximum permissible crack size? What is the service life of a structure when a certain pre-existing flaw size (e.g. a manufacturing defect) is assumed to exist? During the period available for crack detection how often should the structure be inspected for cracks?
== History == The first Mel's Drive-In was founded in 1947 by Mel Weiss and Harold Dobbs in San Francisco, California. It later expanded to several other locations. After the last of the original restaurants closed in the 1970s, Weiss's son Steven Weiss and partner Donald Wagstaff opened the first of a new generation of Mel's Drive-In restaurants in 1985. A family rift between father and son caused them to part ways and form two chains, with Steven retaining the "Mel's Drive-In" name and Mel calling his restaurants "Original Mels". The elder Weiss then sold his company in 1994. The Original Mels locations are not listed on the official Mel's Drive-In website, and vice versa.
=== Pseudobulbar affect === In 2010, the FDA approved the combination drug dextromethorphan/quinidine under the brand name Nuedexta for the treatment of pseudobulbar affect (uncontrollable laughing/crying). Dextromethorphan is the active therapeutic agent in the combination; quinidine merely serves to inhibit the enzymatic degradation of dextromethorphan and thereby increase its circulating concentrations via inhibition of CYP2D6.
Dr (Heinz) Wuschech knows more about anabolic steroids than any doctor I have ever met, and yet he cannot discuss them openly any more than Geoff Capes or Mac Wilkins can openly discuss them in the current climate of amateur sports regulation. What I did learn in East Germany was that they feel there is little danger from anabolica, as they call it, when the athletes are kept on strictly monitored programmes. Although the extremely dangerous side-effects are admitted, they are statistically no more likely to occur than side-effects from the birth control pill. If, that is, programmes are constantly medically monitored as to dosage. Other reports came from the occasional athlete who fled to the West – 15 of them between 1976 and 1979. One, the ski-jumper Hans-Georg Aschenbach, said: "Long-distance skiers start having injections to their knees from the age 14 because of their intensive training." He said: "For every Olympic champion, there are at least 350 invalids. There are gymnasts among the girls who have to wear corsets from the age of 18 because their spine and their ligaments have become so worn... There are young people so worn out by the intensive training that they come out of it mentally blank [lessivés – washed out], which is even more painful than a deformed spine." After the 1990 German reunification, on 26 August 1993 the records were opened and evidence found that the Stasi, the state secret police, supervised systematic doping of East German athletes from 1971 until reunification in 1990.
Afterwards, the two leaders and their wives proceeded to the White House Rose Garden for a Military Review. The United States Air Force Honor Guard presenting American and Chinese flags were positioned upon the roof of West Wing Colonnade; BBC News observed it is "highly unusual to see uniformed soldiers standing at attention above the Oval Office" and remarked the welcome for Xi "has far exceeded the welcome given other visiting heads of state in Trump's second term". The 15‑minute presentation included the Old Guard Fife and Drum Corps dressed in Continental Army dress uniforms, the US Marine Corps Silent Drill Platoon and the United States Marine Drum and Bugle Corps performances with a flyover finale featuring a B-2 Spirit and four F-22 Raptors. Cai Qi, Wang Yi, JD Vance and his wife Usha Vance, and Ivanka Trump were also present at the ceremony. Afterwards, the two leaders and their respective contingents went to the Oval Office to start their meeting. which lasted for 90 minutes. Xi was accompanied by CCP General Office Director Cai Qi, Vice Premier He Lifeng, Central Foreign Affairs Commission Office Director and Foreign Minister Wang Yi, National Development and Reform Commission Director Zheng Shanjie, and Minister of Commerce Wang Wentao. Trump was joined by Vice President JD Vance, Secretary of State Marco Rubio, Secretary of Treasury Scott Bessent, White House Chief of Staff Susie Wiles and Secretary of Defense Pete Hegseth.
Sources: en.wikipedia.org
== Origin == The Kalyāṇakāraka, composed in South India by Ugrāditya, is the earliest medical work to contain alchemical content. It is datable to the early ninth century CE. It gives descriptions for the processing of mercury and uses technical terminology related to the procedures and implements required for alchemy. It is the first work to describe purifying (śodhana) and calcining (māraṇaʼ) mercury for medicinal use. The first work of the Sanskrit alchemical literary genre called rasaśāstra is the 10th century Rasahṛdayatantra. The texts 19 chapters focus on the processing mercury, outlines 18 means to process mercury and discusses the transmutation of metals and the body.
(R(H)N)2CS + HgO → (RN)2C + HgS + H2O This reaction can often be conducted as stated, even though carbodiimides react with water. In some cases, a dehydrating agent is added to the reaction mixture. The dehydration of N,N'-dialkylureas gives carbodiimides:
On the other hand, by inhibiting miR-33 function, the level of ABCA1 is increased, which increases the cholesterol efflux to apoA-1. Suppression of miR-33 will lead to less cellular cholesterol and higher plasma HDL level through the regulation of ABCA1 expression.
== Prevention by food == Scurvy can be prevented by a diet that includes uncooked vitamin C-rich foods providing as little as 10 mg of vitamin C per day. Common examples in typical serving amounts include kiwifruit, grapefruit, strawberries, bell peppers, and citrus fruits. About five servings per day of fresh fruits and vegetables supply enough vitamin C to exceed the scurvy threshold by 10-fold. Nutritional supplements that provide ascorbic acid well above what is required to prevent scurvy may cause adverse health effects. Uncooked fresh meat from animals, notably internal organs such as liver, contains enough vitamin C to prevent scurvy, and even partly treat it. Scott's 1902 Antarctic expedition used fresh seal meat and increased allowance of bottled fruits which reportedly led to complete recovery from incipient scurvy in less than two weeks.
Resistance to lidocaine and bupivacaine is not uncommon, and mepivacaine tends to work better in people with EDS. Special recommendations for anesthesia are given for people with EDS. Detailed recommendations for anesthesia and perioperative care of people with EDS should be used to improve safety. Surgery in people with EDS requires careful tissue handling and a longer immobilization afterward.
Sources: en.wikipedia.org
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.
Freezing determines ice crystal size, pore structure, and the concentration of solutes in remaining liquid. Faster freezing generally creates smaller ice crystals and a denser dried matrix. These features affect drying rate and reconstitution behavior.
Lyophilization reduces water content but usually leaves a small amount of water in the dried material. Some water remains bound to solids or trapped in the dried matrix. Very low water targets can require extended secondary drying, which may alter product stability.
Karl Fischer titration is a common reference method that quantifies water by a chemical reaction. Thermogravimetric analysis can also estimate moisture by weight loss on heating. Method choice depends on sample size and whether other volatile substances are present.