collapse temperature 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 2026-03-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
A formulation often contains excipients that protect the active ingredient during freezing and drying. Bulking agents provide structure, while lyoprotectants stabilize sensitive molecules. The freezing step can produce ice crystals whose size and distribution affect the drying rate, and cycle design includes freezing, annealing, and drying phases. If the product temperature rises above a critical value, the cake may collapse or lose its porous structure. Successful lyophilization therefore depends on the interaction between formulation, equipment, and cycle design.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
Freezing determines ice crystal structure and pore size, which affect drying speed and product uniformity. Rapid freezing creates small crystals, while slow freezing creates larger crystals and often faster sublimation. During primary drying, chamber pressure is held below the vapor pressure of ice, and shelf temperature supplies heat for sublimation. The ice front recedes, leaving a porous matrix. Thermal limits such as collapse and eutectic temperatures set safe boundaries for formulation. These limits vary with solute composition and concentration.
| 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 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.
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.
==== Operation Safe Veracruz ==== In response to the multiple executions between the drug cartels, the federal government launched a military-led operation in the state of Veracruz, known in Spanish as Operativo Veracruz Seguro. In October 2011, the state of Veracruz was a disputed territory between Los Zetas and the Gulf Cartel and Sinaloa Cartel. Francisco Blake Mora, Secretary of the Interior at the time, said that the operation was implemented to serve the following goals:
Magnetic resonance imaging (MRI) is a powerful tool for disease diagnosis such as cancer metastasis and inflammation, using different metal chelates. Metal chelates increase the contrast signal between normal and diseased tissues by catalyzing the relaxation of water protons in their proximities. Typical examples are Gd3+ low-molecular-weight chelates, and superparamagnetic iron oxide (SPIO). In vivo administration of these agents allows the labeling of tumor cells; or cells can be labeled in vitro with contrast agents and then they can be injected and monitored in vivo by using MRI techniques. SPIO nanoparticles confer high sensitivity in MRI but they have lower affinity for cells; they work at high concentrations. Functionalizations of these compounds using dendrimeric guanidines showed similar activities as TAT-based CPPs but higher toxicity. New substrates based on dendrons with hydroxyl or amine peripheries show low toxicity. Applications of SPIO includes cell labeling in vivo; due to low toxicity, they are clinically approved for use in liver, spleen, and gastrointestinal imaging. The presence of octamer arginine residues allows cell membrane transduction of various cargo molecules including peptides, DNA, siRNA, and contrast agents. However, the ability of cross membrane is not unidirectional; arginine-based CPPs are able to enter-exit the cell membrane, displaying an overall decreasing concentration of contrast agent and a decrease of magnetic resonance (MR) signal in time. This limits their application in vivo.
Vitamin C or ascorbate is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is found as a form of ascorbic acid. It is an essential nutrient involved in the repair of tissue, the formation of collagen, and the enzymatic production of certain neurotransmitters. It is required for the functioning of several enzymes and is important for immune system function. It is also an antioxidant. Most animals are able to synthesize their own vitamin C. However, higher primates (including humans), most bats, guinea pigs, some fish species, and some bird species must acquire it from dietary sources because a gene for a synthesis enzyme has mutations that render it dysfunctional; humans obtain this vitamin from those fruits and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription dietary supplement. As a therapy, it is used to prevent and treat scurvy, a disease caused by vitamin C deficiency. Vitamin C may be taken by mouth or by intramuscular, subcutaneous or intravenous injection. Various health claims exist on the supposition that moderate vitamin C deficiency increases disease risk, such as for the common cold, cancer or COVID-19. There are also claims of benefits from vitamin C supplementation in excess of the recommended dietary intake for people who are not considered vitamin C deficient. Vitamin C is generally well tolerated. Large doses may cause gastrointestinal discomfort, headache, trouble sleeping, and flushing of the skin.
=== Synthesis === The synthesis of diazepam was first achieved through a reaction pathway developed by Leo Sternbach and his team at Hoffmann-La Roche in the late 1950s. Sternbach's method commenced with 2-amino-5-chlorobenzophenone, which undergoes cyclocondensation with glycine ethyl ester hydrochloride to construct the benzodiazepine core. This core is subsequently alkylated at the nitrogen in the 1-position using dimethyl sulfate in the presence of sodium methoxide and methanol under reflux conditions. Although the direct transformation from 2-amino-5-chlorobenzophenone to Nordazepam is conceptually straightforward, an alternative approach involving the treatment of 2-amino-5-chlorobenzophenone with chloroacetyl chloride, succeeded by ammoniation and heating, culminates in Nordazepam with enhanced yield and facilitates easier purification processes.
In this study, the UK school children had a low baseline cellular immunity to mycobacteria which was increased by BCG; in contrast, the Malawi school children had a high baseline cellular immunity to mycobacteria and this was not significantly increased by BCG. Whether this natural immune response is protective is not known. An alternative explanation is suggested by mouse studies; immunity against mycobacteria stops BCG from replicating and so stops it from producing an immune response. This is called the block hypothesis. Interference by concurrent parasitic infection In another hypothesis, simultaneous infection with parasites such as helminthiasis changes the immune response to BCG, making it less effective. As Th1 response is required for an effective immune response to tuberculous infection, but concurrent infection with various parasites produces a simultaneous Th2 response, which blunts the effect of BCG.
Sources: en.wikipedia.org
== History == Curcumin was named in 1815 when Henri Auguste Vogel and Pierre Joseph Pelletier reported the first isolation of a "yellow coloring-matter" from the rhizomes of turmeric. Later, it was found to be a mixture of resin and turmeric oil. In 1910, Milobedzka and Lampe reported the chemical structure of curcumin to be as diferuloylmethane. Later in 1913, the same group accomplished the synthesis of the compound. Although used in traditional medicine, the possible therapeutic properties of turmeric or curcumin remain undetermined.
While the main habitat of earthworms is in soil, they are not restricted to this habitat. The brandling worm Eisenia fetida lives in decaying plant matter and manure. Arctiostrotus vancouverensis from Vancouver Island and the Olympic Peninsula is generally found in decaying conifer logs. Aporrectodea limicola, Sparganophilus spp., and several others are found in mud in streams (riparian species). Some species are arboreal, some aquatic and some euryhaline (salt-water tolerant) and littoral (living on the sea-shore), e.g. Pontodrilus litoralis. Even in the soil species, special habitats, such as ultramafic soils derived from serpentine, have an earthworm fauna of their own, e.g. New Caledonian Acanthodrilidae. Vermicomposting of organic wastes is currently processed using the epigeic Eisenia fetida and Eisenia andrei which are particularly adapted to the consumption of fresh organic matter without deepening in the substrate (contrary to the anecis Lumbricus terrestris) and which tolerate the heat generated in compost heaps. Addition of this humified organic matter to the soil, preferably as a surface mulch, will improve moisture and nutrient availability, with beneficial effects on the soil microflora. It will also provide several species of earthworms with their food and nutrient requirements, and will create the optimum conditions of temperature and moisture that will stimulate their activity, although to a lesser extent than bacterial-mediated compost. Earthworms are environmental indicators of soil health.
==== JPT2 ==== The 20kDa Jupiter microtubule-associated homolog 2 (JPT2) (also known as HN1L) was the first accessory protein to be published as a mediator of NAADP-dependent Ca2+ release. Both studies exploited the same novel 'clickable' NAADP photoprobe, but regardless of the different blood cell types, the authors converged on the same molecular partner (although the studies differ in the channel that is activated). JPT2 binds [32P]NAADP with selectivity over a spectrum of different nucleotides. In Ca2+-release studies, NAADP-dependent signals were inhibited by siRNA knockdown of JPT2, but not of its homolog, JPT1, attesting to isoform specificity. Interestingly, JPT2 exhibited a preferential interaction with TPC1 over TPC2. Given that TPCs are known to drive pathogen uptake into cells, it was striking that uptake of a Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudovirus was likewise reduced by JPT2 gene silencing.
On 12–13 December 1981, the regime declared martial law in Poland, under which the army and the ZOMO special police forces were used to crush Solidarity. The Soviet leaders insisted that Jaruzelski pacifies the opposition with the forces at his disposal, without Soviet involvement. Almost all Solidarity leaders and many affiliated intellectuals were arrested or detained. Nine workers were killed in the Pacification of Wujek. The United States and other Western countries responded by imposing economic sanctions against Poland and the Soviet Union. Unrest in the country was subdued, but continued. During martial law, Poland was ruled by the so-called Military Council of National Salvation. The open or semi-open opposition communications, as recently practiced, were replaced by underground publishing (known in the eastern bloc as Samizdat), and Solidarity was reduced to a few thousand underground activists. Having achieved some semblance of stability, the Polish regime relaxed and then rescinded martial law over several stages. By December 1982 martial law was suspended and a small number of political prisoners, including Wałęsa, were released. Although martial law formally ended in July 1983 and a partial amnesty was enacted, several hundred political prisoners remained in jail. Jerzy Popiełuszko, a popular pro-Solidarity priest, was abducted and murdered by security functionaries in October 1984.
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.
Conventional drying uses heat to evaporate liquid water, often at temperatures that can degrade sensitive materials. Lyophilization freezes the material first and then removes water by sublimation under vacuum. This avoids prolonged exposure to liquid water and high heat.