sublimation is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-10-25. 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.
Storage stability depends on water content, oxygen exposure, and temperature. Lyophilized solids are hygroscopic and can absorb water if exposed to humid air. Vials are usually sealed under vacuum or inert gas with rubber stoppers and aluminum crimps. Storage temperatures range from room temperature to refrigerated or frozen conditions depending on the material. Stability studies track potency, moisture, and physical form over time. Accelerated conditions can reveal sensitivity but may not predict long-term behavior.
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.
| 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 |
Protodioscin is a steroidal saponin compound found in a number of plant species, most notably in the Tribulus, Trigonella Dioscorea and Trillium families. It is best known as the putative active component of the herbal aphrodisiac plant Tribulus terrestris. Extracts of T. terrestris standardized for protodioscin content have been shown to produce proerectile effects in isolated tissues and aphrodisiac activity in several animal models. Protodioscin is thought to contribute to increased androgen receptor immunoreactivity in some tissues, likely as a secondary effect of elevated levels of endogenous androgens such as testosterone and dihydrotestosterone (DHT). This increase in androgen receptor immunoreactivity has been observed after administration of Tribulus terrestris extracts, but current evidence does not support the view that protodioscin acts primarily or directly by raising the density of androgen receptors; instead, it may enhance androgen receptor expression indirectly through its influence on androgen levels. Although the precise mechanism has not been fully established, protodioscin has been reported to stimulate the release of nitric oxide in corpus cavernosum tissue, as well as to significantly increase circulating levels of testosterone, dihydrotestosterone, and dehydroepiandrosterone in animal studies. However, clinical studies in humans have not demonstrated consistent efficacy, and the therapeutic value of T. terrestris extracts remains controversial.
=== 8 April === Three people were killed and eight others were injured in a Russian missile attack on Zaporizhzhia. One person was killed and five others were injured in Russian air strikes in Sumy Oblast. Two people were killed in separate attacks in Chasiv Yar and Poltava. Ukrainian hackers launched a cyberattack on a data center used by the Russian military, energy, and telecommunications industries, which affected 10,000 enterprises including Gazprom and Lukoil. The SBU arrested a former member of the Party of Regions in Sumy Oblast on suspicion of spying for Russia.
Gold fingerprinting is a method used to identify and authenticate gold items by analyzing the unique composition of impurities or trace elements within the metal. While gold itself is an inert and relatively uniform element, gold found in natural or processed items often contains small amounts of other elements, such as silver or lead. These trace elements, which vary depending on the source and refining process, serve as a "fingerprint" for the gold. By comparing the elemental composition of a gold sample to databases of known sources, experts can determine where the gold was likely mined or processed. This technique is applied in fields such as archaeology, geology, and forensic science, as it provides insights into the provenance of historical artifacts, mined gold, or stolen items.
=== Bacterial susceptibility === Cefuroxime axetil treats infections against methicillin-, oxacillin- and penicillin-sensitive bacterial strains. Cefuroxime axetil does not work against enterococci. Gram-positive aerobic microorganisms
Sources: en.wikipedia.org
== History == In 1822 the first awards were given to thirteen people by the Philadelphia Society for Promoting Agriculture entrusted by the "Corporation of the city of Philadelphia". The druggist John Scott of Edinburgh organized a $4,000 fund which, after his death in 1815 was administered by a merchant until the first award, a copper medal and "an amount not to exceed twenty dollars", was given in 1822. (At the time, $20 could buy one ox or a 12-volume encyclopedia.) Several hundred recipients have since been selected by the City Council of Philadelphia, which decides from the annual list of nominees made by the Franklin Institute.
In all other aspects, however, the RF government perpetuated existing racial segregation and inequalities: the white minority's economic domination and ownership of land was maintained, as was the racial segregation of public services, education and electoral rolls through the party's policy of "separate economic advancement". In contrast to the National Party, whose rule expanded and escalated white domination, the RF sought mainly, with some notable exceptions, to maintain minority rule through inexplicit means. Before the RF's rise to power, separate 'A' and 'B' electoral rolls based on differing income and property qualifications had already de facto disenfranchised the black electorate for decades, with the larger 'A' roll mainly consisting of the wealthier white minority, and the smaller 'B' roll almost exclusively consisting of the small number of Africans eligible and willing to register. Combined with a largely successful boycott campaign from the black majority, this resulted in de facto white minority rule. In an exception to their usual policies, the 1969 constitutional reform explicitly delineated the two electoral rolls by race: With the European 'A' roll increased to 50 seats as opposed to the African 'B' roll only having 8 (with an additional 8 indirectly elected to represent chiefs and tribal interests), this resulted in 270,000 whites having 50 seats and 6 million Africans having 16 seats in the Assembly. These reforms only served to reinforce black rejection of the system.
=== Cellular co-operation === P. aeruginosa relies on iron as a nutrient source to grow. However, iron is not easily accessible because it is not commonly found in the environment. Iron is usually found in a largely insoluble ferric form. Furthermore, excessively high levels of iron can be toxic to P. aeruginosa. To overcome this and regulate proper intake of iron, P. aeruginosa uses siderophores, which are secreted molecules that bind and transport iron. These iron-siderophore complexes, however, are not specific. The bacterium that produced the siderophores does not necessarily receive the direct benefit of iron intake. Rather, all members of the cellular population are equally likely to access the iron-siderophore complexes. Members of the cellular population that can efficiently produce these siderophores are commonly referred to as cooperators; members that produce little to no siderophores are often referred to as cheaters. Research has shown when cooperators and cheaters are grown together, cooperators have a decrease in fitness, while cheaters have an increase in fitness. The magnitude of change in fitness increases with increasing iron limitation. With an increase in fitness, the cheaters can outcompete the cooperators; this leads to an overall decrease in fitness of the group, due to lack of sufficient siderophore production. These observations suggest that having a mix of cooperators and cheaters can reduce the virulent nature of P. aeruginosa.
Hankinson's equation (also called Hankinson's formula or Hankinson's criterion) is a mathematical relationship for predicting the off-axis uniaxial compressive strength of wood. The formula can also be used to compute the fiber stress or the stress wave velocity at the elastic limit as a function of grain angle in wood. For a wood that has uniaxial compressive strengths of
In 2025, Portugal had a population of 11,424,031, of whom 9,826,492 were Portuguese nationals. The remainder were foreign residents at 1,597,539. Portugal is steadily ageing and has one of the world's highest proportion of elderly citizens, comprising nearly one-fourth of its entire population, together with a female share of the population at 51.1%. In 2025, Portugal had a fertility rate of 1.4, which is below the replacement rate of 2.1 and is one of the world's lowest. Portugal has had a fertility rate below the replacement rate of 2.1 since the 1980s that has led to the country having a median age of 45.8, one of the highest in the world. As of 2025, 23.3% of the population was aged 65 or older. Despite the effects of net migration, due to low fertility rates, Portugal's population is projected to drop to 8.3 million by 2100. Historically a country of emigration, Portugal has been a net recipient of immigrants since 1993 except between 2011 and 2016 during the Portuguese financial crisis. Since 2016, Portugal has experienced a marked increase in immigration, with the proportion of non-nationals in the total population rising from 3.5% to 14.0% by 2025, living mainly in the Algarve and the Lisbon metropolitan area, and with 24.5% of all births registered in 2024 being to foreign-born women. In Portugal, White Portuguese constitute the largest racial and ethnic group, representing 84.2% of the population, followed by multiracial Portuguese at 3.4%, Black Portuguese at 2.2%, Asian Portuguese at 0.7%, and the Romani at 0.6%.
Sources: en.wikipedia.org
An interview with Francis Crick and Christof Koch, 2001 Archived 3 March 2009 at the Wayback Machine Listen to Francis Crick The Quest for Consciousness Archived 3 March 2009 at the Wayback Machine – The Quest for Consciousness – 65 minute audio program — a conversation on Consciousness with neurobiologist Francis Crick of the Salk Institute and neurobiologist Christof Koch from Caltech. Listen to Francis Crick and James Watson talking on the BBC in 1962, 1972, and 1974. The Impact of Linus Pauling on Molecular Biology – a 1995 talk delivered by Crick at Oregon State University About his work
=== Motion sickness === Meclizine is effective in inhibiting nausea, vomiting, and dizziness caused by motion sickness. The drug is safe for treating nausea in pregnancy and is a first-line therapy for this use. Meclizine may not be strong enough for especially sickening motion stimuli, and second-line defenses should be tried in those cases.
The predecessor to the CAD, termed an evaporative electrical detector, was first described by Kaufman in 2002 at TSI Inc in US patent 6,568,245 and was based on the coupling of liquid chromatographic approaches to TSI's electrical aerosol measurement (EAM) technology. At around the same time Dixon and Peterson at California State University were investigating the coupling of liquid chromatography to an earlier version of TSI's EAM technology, which they called an aerosol charge detector. Subsequent collaboration between TSI and ESA Biosciences Inc. (now part of Thermo Fisher Scientific), led to the first commercial instrument, the Corona CAD, which received both the Pittsburgh Conference Silver Pittcon Editor's Award (2005) and R&D 100 award (2005). Continued research and engineering improvements in product design resulted in CADs with ever increasing capabilities. The newest iterations of the CAD are the Thermo Scientific Corona Veo Charged Aerosol Detector, Corona Veo RS Charged Aerosol Detector and Thermo Scientific Vanquish Charged Aerosol Detectors.
Human ASH1L protein is 2969 amino acids long with a molecular weight of 333 kDa. ASH1L has an associated with SET domain (AWS), a SET domain, a post-set domain, a bromodomain, a bromo-adjacent homology domain, and a plant homeodomain finger (PHD finger). Human and Drosophila Ash1 share 66% and 77% similarity in their SET and PHD finger domains, respectively. A bromodomain is not present in Drosophila Ash1. The SET domain is responsible for ASH1L's histone methyltransferase (HMTase) activity. Unlike other proteins that contain a SET domain at their C terminus, ASH1L has a SET domain in the middle of the protein. The crystal structure of the human ASH1L catalytic domain, including the AWS, SET, and post-SET domains, has been solved to 2.9 angstrom resolution. The structure shows that the substrate binding pocket is blocked by a loop from the post-SET domain, and because mutation of the loop stimulates ASH1L HMTase activity, it was proposed that this loop serves a regulatory role.
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.
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.