This is a working overview of primary drying, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-26. Anything still debated is marked as such rather than presented as settled.
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.
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 typical cycle begins with freezing, sometimes including an annealing step to control ice crystal size. Freezing conditions influence the pore network that later allows vapor escape. During primary drying, shelf temperature and chamber pressure are set so heat enters the product while its temperature stays below the collapse or eutectic point. Secondary drying then raises the shelf temperature to desorb bound water and lower residual moisture. Cycle design depends on formulation, fill volume, container type, and equipment capability.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white porous cake | Color and texture vary with formulation. |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity, excipients, and diluent. |
| Typical moisture level | 0.5-3% w/w | Lower values suit hydrolysis-sensitive materials. |
| Common moisture method | Karl Fischer titration | Coulometric mode is common for low water levels. |
| Typical storage temperature | 2-8 °C or ambient | Some products require frozen storage; protect from humidity. |
=== Other === Cosmetics; Medical makeup can temporarily conceal scars. This is most commonly used for facial scars. Dermabrasion involves the removal of the surface of the skin with special equipment, and usually involves a local anaesthetic. A 2012 literature review found weak evidence that massage was efficacious in scar management. Any beneficial effect appeared to be greater in wounds created by surgical incision than for traumatic or burn wounds. A 2022 scoping review covering twenty-five studies of 1515 participants reported that all studies reviewed reported favorable outcomes for scar massage, but that "while there may be benefits to scar massage in reducing pain, increasing movement and improving scar characteristics", there was a lack of "consistent research methods, intervention protocols and outcome measures". Microneedling
Upon further compression to 23 GPa, americium transforms to an orthorhombic γ-Am structure similar to that of α-uranium. There are no further transitions observed up to 52 GPa, except for an appearance of a monoclinic phase at pressures between 10 and 15 GPa. There is no consistency on the status of this phase in the literature, which also sometimes lists the α, β and γ phases as I, II and III. The β-γ transition is accompanied by a 6% decrease in the crystal volume; although theory also predicts a significant volume change for the α-β transition, it is not observed experimentally. The pressure of the α-β transition decreases with increasing temperature, and when α-americium is heated at ambient pressure, at 770 °C it changes into an fcc phase which is different from β-Am, and at 1075 °C it converts to a body-centered cubic structure. The pressure-temperature phase diagram of americium is thus rather similar to those of lanthanum, praseodymium and neodymium. As with many other actinides, self-damage of the crystal structure due to alpha-particle irradiation is intrinsic to americium. It is especially noticeable at low temperatures, where the mobility of the produced structure defects is relatively low, by broadening of X-ray diffraction peaks. This effect makes somewhat uncertain the temperature of americium and some of its properties, such as electrical resistivity. So for americium-241, the resistivity at 4.2 K increases with time from about 2 μOhm·cm to 10 μOhm·cm after 40 hours, and saturates at about 16 μOhm·cm after 140 hours.
For example, controlled-release oxycodone (OxyContin) or morphine (MS-Contin) are intended to, via novel delivery mechanisms, permit pain relief for up to twelve hours with an active ingredient which only provides relief for 3 to 6 hours. However, the inherent variability amongst different people with respect to drug metabolism makes this task challenging.
, in order to characterize the geometry. This correction factor, also often referred to as the geometric shape factor, is given by empirically determined series and accounts for the type and geometry of the crack or notch. We thus have:
A number of health benefits of tocotrienols have been proposed, including decreased risk of age-associated cognitive impairment, heart disease and cancer. Reviews of human research linked tocotrienol treatment to improved biomarkers for inflammation and cardiovascular disease, although those reviews did not report any information on clinically significant disease outcomes. Biomarkers for other diseases were not affected by tocotrienol supplementation.
Sources: en.wikipedia.org
== Characteristics == Limosilactobacillus fermentum belongs to the genus Limosilactobacillus. Species in this genus are heterofermentative and adapted to the intestinal tract of vertebrates but also used for a wide variety of applications including food and feed fermentation. L. fermentum differs from most or all other species in the genus as it has a nomadic lifestyle and is not a stable member of human or animal intestinal microbiota. It has been found that some strains for L. fermentum have natural resistances to certain antibiotics and chemotherapeutics. They are considered potential vectors of antibiotic resistance genes from the environment to humans or animals to humans. Some strains of L. fermentum have been associated with cholesterol metabolism.
Lipid vesicles or liposomes are approximately spherical pockets that are enclosed by a lipid bilayer. These structures are used in laboratories to study the effects of chemicals in cells by delivering these chemicals directly to the cell, as well as getting more insight into cell membrane permeability. Lipid vesicles and liposomes are formed by first suspending a lipid in an aqueous solution then agitating the mixture through sonication, resulting in a vesicle. Measuring the rate of efflux from the inside of the vesicle to the ambient solution allows researchers to better understand membrane permeability. Vesicles can be formed with molecules and ions inside the vesicle by forming the vesicle with the desired molecule or ion present in the solution. Proteins can also be embedded into the membrane through solubilizing the desired proteins in the presence of detergents and attaching them to the phospholipids in which the liposome is formed. These provide researchers with a tool to examine various membrane protein functions.
=== Low dispersion lenses === Thorium was also used in certain glass elements of Aero-Ektar lenses made by Kodak during World War II. Thus they are mildly radioactive. Two of the glass elements in the f/2.5 Aero-Ektar lenses are 11% and 13% thorium by weight. The thorium-containing glasses were used because they have a high refractive index with a low dispersion (variation of index with wavelength), a highly desirable property. Many surviving Aero-Ektar lenses have a tea colored tint, possibly due to radiation damage to the glass. These lenses were used for aerial reconnaissance because the radiation level is not high enough to fog film over a short period. This would indicate the radiation level is reasonably safe. However, when not in use, it would be prudent to store these lenses as far as possible from normally inhabited areas; allowing the inverse square relationship to attenuate the radiation.
== History == The first described attempts at producing weight loss are those of Soranus of Ephesus, a Greek physician, in the second century AD. He prescribed elixirs of laxatives and purgatives, as well as heat, massage, and exercise. This remained the mainstay of treatment for well over a thousand years. It was not until the 1920s and 1930s that new treatments began to appear. Based on its effectiveness for hypothyroidism, thyroid hormone became a popular treatment for obesity in euthyroid people. It had a modest effect but produced the symptoms of hyperthyroidism as a side effect, such as palpitations and difficulty sleeping. 2,4-Dinitrophenol (DNP) was introduced in 1933; this worked by uncoupling the biological process of oxidative phosphorylation in mitochondria, causing them to produce heat instead of ATP. Overdose caused fatal hyperthermia and DNP also caused cataracts in some users. After the passage of the Food, Drug, and Cosmetic Act in 1938, the FDA banned DNP for human consumption. Amphetamines (marketed as Benzedrine) became popular for weight loss during the late 1930s. They worked primarily by suppressing appetite, and had other beneficial effects such as increased alertness. Use of amphetamines increased over the subsequent decades, including Obetrol and culminating in the "rainbow diet pill" regime. This was a combination of multiple pills, all thought to help with weight loss, taken throughout the day.
==== 2010-2012 ==== Russian journalist Yulia Latynina stated in January 2010 that she had been told by numerous NATO military attaches that Russia had been preparing for this war for 4 years and Russian tanks entered South Ossetia before the full-scale war between Georgia and Russia. In January 2010, Russian military portal Zaotechestvo.ru published the recollections of several Russian soldiers. Aleksandr Slanov, the head of the North Ossetian regional branch of "Union of Paratroopers", the NGO of veterans of the Airborne Forces and Special Forces, said: "In the night of 4–5 August, I and five other paratroopers left for Tskhinvali. We arrived at 5 AM." Tank operator Vladimir said: "We arrived in Khetagurovo in the morning of 7 August. Our task was to destroy the Georgian fortified district, that was located on the height near Khetagurovo." Soldier Aleksandr from military special forces said that his unit was being trained for something already in July 2008 and they had to sign a paper that they voluntarily agreed to training for an indefinite period. According to Aleksandr, this meant that actually there was no drill and they were informed of the war after they were already on move. In July 2010, the Prosecutor General's Office of the Russian Federation announced that a case of Eduard Gobozov, employee of the Ministry of Defence of the Republic of South Ossetia, was sent to the court in North Ossetia. Gobozov was accused of treason.
Sources: en.wikipedia.org
Karl Fischer titration is a common method, using coulometric or volumetric detection. Thermogravimetric analysis can also measure weight loss on heating. Results depend on sample handling because the dried solid can absorb moisture quickly.
The porous cake readily absorbs water vapor from air, which can reduce stability or cause collapse. Vials are sealed with stoppers and crimp seals, sometimes under vacuum or inert gas. Packaging also protects against oxygen and mechanical damage.
Collapse occurs when the product temperature rises above its collapse threshold during primary drying. The ice matrix loses structure, and the cake may shrink or melt back. Formulation excipients and freezing rate influence collapse threshold.
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.