glass transition raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-09-23 and is reviewed periodically as new material appears.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilisation is the British spelling; the process is not simple evaporation. |
| Primary drying pressure | 0.05–0.3 mbar | Pressure must remain below the vapor pressure of ice at the product temperature. |
| Sublimation temperature | Below 0 °C | Ice changes directly to vapor while the product remains frozen. |
| Typical shelf temperature | −40 to −10 °C | Exact setting depends on formulation critical temperature and equipment. |
| Cycle duration | 12–72 hours | Time varies with fill volume, formulation, and dryer performance. |
"p53 Knowledgebase". Lane Group at the Institute of Molecular and Cell Biology (IMCB), Singapore. Archived from the original on 2006-01-03. Retrieved 2008-04-06. GeneReviews/NCBI/NIH/UW entry on Li-Fraumeni Syndrome TUMOR PROTEIN p53 @ OMIM p53 restoration of function p53 @ The Atlas of Genetics and Cytogenetics in Oncology and Haematology TP53 Gene @ GeneCards p53 News provided by insciences organisation Goodsel DS (2002-07-01). "p53 Tumor Suppressor". Molecule of the Month. RCSB Protein Data Bank. Retrieved 2008-04-06. Soussi T. "p53 Web Site". Retrieved 2008-04-06. Living LFS A non-profit Li-Fraumeni Syndrome patient support organization The George Pantziarka TP53 Trust A support group from the UK for people with Li-Fraumeni Syndrome or other TP53-related disorders IARC TP53 Somatic Mutations database maintained at IARC, Lyon, by Magali Olivier PDBe-KB provides an overview of all the structure information available in the PDB for Human P53. scientific animation conformational changes of p53 upon binding to DNA
=== Lethality === Calciseptine is toxic in low doses. No specific data are available on the toxicity of calciseptine in humans. However, the LD50 values for mice have been determined and can be found in the table below:
The discovery of an orally inactive peptide from the skin of poisonous frogs established the important role of angiotensin converting enzyme (ACE) inhibitors in regulating blood pressure. This led to the development of captopril, the first ACE inhibitor. When the adverse effects of captopril became apparent new derivates were designed. Then after the discovery of two active sites of ACE: N-domain and C-domain, the development of domain-specific ACE inhibitors began.
In January 2010, at President Obama's request, Bush and Bill Clinton established the Clinton Bush Haiti Fund to raise contributions for relief and recovery efforts after the 2010 Haiti earthquake earlier that month. On May 2, 2011, President Obama called Bush, who was at a restaurant with his wife, to inform him that Osama bin Laden had been killed. The Bushes joined the Obamas in New York City to mark the tenth anniversary of the September 11, 2001, terrorist attacks. At the Ground Zero memorial, Bush read a letter that President Abraham Lincoln wrote to a widow who had lost five sons during the Civil War. On September 7, 2017, Bush partnered with former presidents Jimmy Carter, George H. W. Bush, Bill Clinton, and Barack Obama to work with One America Appeal to help the victims of Hurricane Harvey and Hurricane Irma in the Gulf Coast and Texas communities. Over the years, President Bush has had a good-natured friendship with Michelle Obama. "President Bush and I, we are forever seatmates because of protocol, and that's how we sit at all the official functions," Obama told the Today Show. "He's my partner in crime at every major thing where all the 'formers' gather. So we're together all the time." Bush famously passed mints to Obama during the McCain funeral in September 2018 and gave them to her again during the funeral of his father in December 2018.
Sources: en.wikipedia.org
== Blood plasma == Blood plasma is the liquid component of whole blood, and makes up approximately 55% of the total blood volume. It is composed primarily of water with small amounts of minerals, salts, ions, nutrients, and proteins in solution. In whole blood, red blood cells, leukocytes, and platelets are suspended within the plasma.
Despite the strong military presence, the authorities discovered seven bodies inside a Ford Lobo on 8 October 2011 in Veracruz. On 22 December 2011, three public buses were attacked by drug cartel members on Federal Highway 105 in Veracruz, leaving 16 dead. Three U.S. citizens were among those dead. Soon after the shootouts, which happened in the early morning, the authorities carried out an operation to find those responsible, killing five gunmen. The U.S. Consulate in Matamoros asked Americans to avoid traveling on highways between cities in the late hours of the night. In Tampico Alto, Veracruz, on 23 December 2011 the Mexican authorities found 10 dead bodies after an anonymous call from a citizen. The corpses were dumped on a dirt road, and all of them were handcuffed and presented signs of torture. Nine out of the ten bodies were decapitated. Earlier in February 2011, Saturnino Valdés Llanos, the mayor of the municipality of Tampico Alto, was kidnapped in February 2011; his body was left in a garbage dump with 10 more bodies a week later. On 25 December 2011 near Tampico, Tamaulipas, a city on the border with Veracruz, 13 bodies were found inside an 18-wheeler truck. According to officials, the truck had license plates from Veracruz. Authorities indicated that this massacre was related to the other mass murders that had occurred in Veracruz. On 9 February 2012, the Mexican authorities exhumed 15 bodies from clandestine mass graves in Acayucan, Veracruz.
== Chemical composition == Birch bark tar is mainly composed of triterpenoid compounds of the lupane and oleanane family, which can be used as biomarkers to identify birch bark tar in the archaeological record. The most characteristic molecules are betulin and lupeol, which are also present in birch bark. Some of these molecules degrade into other lupane and oleanane skeleton triterpenes. The most commonly found additional molecules are lupenone, betulone, lupa-2,20(29)-dien-28-ol, lupa-2,20(29)-diene and allobetulin.
=== Detection === Modafinil is considered a stimulant doping agent and as such is prohibited by World Anti-Doping Agency in sports competitions. Modafinil enantiomers can be separately quantified in biological samples.
=== Bacteria === Brine pockets are home to a diverse and dynamic community of marine bacteria which are adapted to survive and thrive in the extreme cold, called psychrophiles. As psychrophiles are adapted to survive and grow at very low temperatures, they are capable of synthesizing enzymes that remain active at low temperatures, allowing them to metabolize in the extremely cold conditions of brine pockets and channels. Bacteria in brine pockets must also be able to tolerate high salt concentrations, so these bacteria are also halophilic. Halophilic psychrophiles are found within Proteobacteria, Actinobacteria and Bacteroidetes. Two Proteobacteria found to be abundant in brine pockets are gammaproteobacteria and alphaproteobacteria. Many gammaproteobacteria are capable of degrading organic matter, making them important for nutrient cycling and organic matter turnover within the brine pocket. For example, aerobic anoxygenic phototrophic (AAP) bacteria are found in marine environments and play a vital role in supporting the electron transport chain by metabolizing bacteriochlorophyll. Alphaproteobacteria include species that are known to be important for nitrogen cycling and carbon cycling in marine environments. Some Alphaproteobacteria are capable of nitrogen fixation, which can provide an important source of nitrogen for other microorganisms within the pocket.
Sources: en.wikipedia.org
=== Supercritical water oxidation === Supercritical water oxidation uses supercritical water as a medium in which to oxidize hazardous waste, eliminating production of toxic combustion products that burning can produce. The waste product to be oxidised is dissolved in the supercritical water along with molecular oxygen (or an oxidising agent that gives up oxygen upon decomposition, e.g. hydrogen peroxide) at which point the oxidation reaction occurs.
For Ajax, Edgar Davids the first penalty taker's shot was saved by Peruzzi. The next two players scored, those being Litmanen and Arnold Scholten. Their final penalty taken by Sonny Silooy was also saved. Jugović's goal was the decisive penalty that gave Juventus its second title in the competition; Juventus won by a score of 4–2.
=== Withdrawals === 1 January 2009 – The U.S.–Iraq Status of Forces Agreement went into effect, and gave the Government of Iraq de jure responsibility of maintaining and providing security for all of its people. Approximately 150,000 foreign troops in Iraq. 28 June 2009 – Foreign forces were no longer stationed within any of Iraq's major cities. Proclaimed as a national holiday by Iraqi Prime Minister Nouri al-Maliki. 31 July 2009 – The last large groups of non-U.S. foreign forces completed their withdrawal from Iraq. 1 January 2010 – The major commands Multi-National Force – Iraq, Multi-National Corps – Iraq and Multi-National Security Transition Command – Iraq merged into the unified command United States Forces – Iraq, reducing the total number of staff positions by 41%. Approximately 112,000 U.S. troops in Iraq. 7 March 2010 – Iraq held parliamentary elections, its second under its democratic constitution, and is seen as an important milestone for the young Iraqi political system; this leaves approximately 96,000 U.S. troops in Iraq. 1 September 2010 – American forces ceased all combat operations, i.e. patrolling, serving arrest warrants, route clearance, etc., and transitioned to a pure advise, train and assist role. Operation Iraqi Freedom is officially concluded, and the advise and assist mission continues under Operation New Dawn. 49,700 U.S. troops in Iraq. 31 December 2011 – U.S. Army and U.S. Marine Corps units and formations complete their withdrawal from Iraq.
Phenylglyoxal is the organic compound with the formula C6H5C(O)C(O)H. It contains both an aldehyde and a ketone functional group. It is yellow liquid when anhydrous but readily forms a colorless crystalline hydrate. It has been used as a reagent to modify the amino acid, arginine. It has also been used to attach chemical payload (probes) to the amino acid citrulline and to peptides/proteins.
Sources: en.wikipedia.org
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.
Freezing determines ice crystal size, solute distribution, and the pore network left after drying. A slow or fast freezing rate can produce different cake structures and affect reconstitution. It also sets whether the formulation follows an amorphous or crystalline drying path.
It removes most free water during primary drying and part of the bound water during secondary drying. A small residual moisture content often remains and is specified for each product. Complete removal is generally neither practical nor desirable for stability.
Collapse occurs when the product temperature rises above its collapse or eutectic temperature during drying. The frozen matrix loses structure, producing a shrunken or melted appearance. This can slow reconstitution and may affect stability.