The short version of Sublimation fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-27. Anything still debated is marked as such rather than presented as settled.
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.
Freeze-dried materials are hygroscopic to varying degrees and can take up moisture after drying. Storage therefore often uses sealed glass vials, rubber stoppers, and crimp seals to limit contact with ambient humidity. A desiccant may be included for moisture-sensitive products, although it is not universal. Controlled room temperature is sufficient for many lyophilizates, while others require refrigeration or freezing. Moisture ingress remains a primary cause of cake collapse, chemical degradation, and loss of reconstitution performance.
Quality assessment of a lyophilized product includes cake appearance, residual moisture, reconstitution time, and container closure integrity. A uniform, porous cake suggests that freezing and drying stayed within the formulation's design space. Cracks, shrinkage, meltback, or a glassy film can indicate thermal abuse or a formulation problem. Analysts also test for subvisible particles and sterility when the product requires those specifications. Visual inspection alone cannot confirm biological activity or chemical stability, so it is combined with analytical methods.
Stability programs monitor lyophilized products under defined temperature and humidity conditions over time. Real-time studies at recommended storage conditions are the reference, while accelerated studies provide early signals of degradation pathways. Because a dry cake can still undergo oxidation, hydrolysis, or aggregation, stability depends on residual moisture, excipients, and container headspace. Open questions include how best to predict long-term stability from short accelerated runs and how vial-to-vial variability affects shelf life. Current guidance treats these predictions as product-specific rather than universally generalizable.
| 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. |
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.
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.
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.
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.
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.
Reconstitution involves adding a suitable diluent, often sterile water or a buffer, to the dried cake. Gentle swirling or inversion helps dissolve the material without creating excessive foam. The time required for complete dissolution can range from seconds to several minutes and depends on the cake structure and the diluent. Improper reconstitution, such as vigorous shaking or using the wrong diluent, can cause protein aggregation or loss of activity. After reconstitution, the product may have a limited shelf life and should be used according to its labeling.
Lyophilized products are typically hygroscopic and require protection from moisture during storage. Manufacturers seal them in glass vials, often under vacuum or an inert gas such as nitrogen. The container closure system, including the stopper and crimp seal, must prevent water vapor ingress. Storage temperature varies from controlled room temperature to refrigerated or frozen conditions, depending on the formulation. Humidity-controlled environments are essential because even brief exposure to ambient air can degrade the product.
Stability of a lyophilized product depends on its glass transition temperature, the temperature at which the amorphous cake transitions from a glassy to a rubbery state. Storage below this temperature minimizes molecular mobility and slows chemical degradation. If the storage temperature exceeds the glass transition temperature, the cake may collapse, shrink, or become sticky. Accelerated stability studies at elevated temperatures and humidity help predict shelf life, but they do not always reflect real-time behavior. Residual moisture content also plays a critical role in long-term stability.
== Composition == Royal jelly is 67% water, 12.5% protein, 11% simple sugars (monosaccharides), 6% fatty acids and 3.5% 10-hydroxy-2-decenoic acid (10-HDA). It also contains trace minerals, antibacterial and antibiotic components, pantothenic acid (vitamin B5), pyridoxine (vitamin B6) and trace amounts of vitamin C, but none of the fat-soluble vitamins: A, D, E or K.
=== Adipose tissue === Insulin resistance in fat cells results in reduced uptake of circulating lipids and increased hydrolysis of stored triglycerides. This leads to elevated free fatty acids in the blood plasma and can further worsen insulin resistance. Since insulin is the primary hormonal signal for energy storage into fat cells, which tend to retain their sensitivity in the face of hepatic and skeletal muscle resistance, insulin resistance stimulates the formation of new fatty tissue and accelerates weight gain. Insulin resistance is strongly associated with intestinal-derived apoB-48 production rate in insulin-resistant subjects and people with type 2 diabetes. Insulin resistance often is found in people with visceral adiposity, hypertension, hyperglycemia, and dyslipidemia involving elevated triglycerides, small dense low-density lipoprotein (sdLDL) particles, and decreased high-density lipoprotein (HDL) cholesterol levels. With respect to visceral adiposity, a great deal of evidence suggests two strong links with insulin resistance. First, unlike subcutaneous adipose tissue, visceral adipose cells produce significant amounts of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-a), and interleukins-1 and -6. In numerous experimental models, these proinflammatory cytokines disrupt normal insulin action in fat and muscle cells and may be a major factor in causing the whole-body insulin resistance observed in patients with visceral adiposity.
=== Palaeolithic and Iron Age === There is evidence of settlement in the Bristol area from the palaeolithic era, with 60,000-year-old archaeological finds at Shirehampton and St Annes. Stone tools made from flint, chert, sandstone and quartzite have been found in terraces of the River Avon, most notably in the neighbourhoods of Shirehampton and Pill. There are Iron Age hill forts near the city, at Leigh Woods and Clifton Down on either side of the Avon Gorge, and at Kingsweston, near Henbury. Bristol was at that time part of the territory of the Dobunni. Evidence of Iron Age farmsteads has been found at excavations throughout Bristol, including a settlement at Filwood. There are also indications of seasonal occupation of the salt marshes at Hallen on the Severn estuary.
Sources: en.wikipedia.org
== Treatment == Stopping high vitamin A intake is the standard treatment. Most people fully recover. Phosphatidylcholine (in the form of PPC or DLPC), the substrate for lecithin retinol acyltransferase, which converts retinol into retinyl esters (the storage forms of vitamin A). Vitamin E may alleviate hypervitaminosis A. Liver transplantation may be a valid option if no improvement occurs. If liver damage has progressed into fibrosis, synthesizing capacity is compromised and supplementation can replenish PC. However, recovery is dependent on removing the causative agent: halting high vitamin A intake.
== Diagnosis == Definitive diagnosis is usually made at a reference laboratory with advanced biocontainment capabilities. The findings of laboratory investigation vary somewhat between the viruses but in general, there is a decrease in the total white cell count (particularly the lymphocytes), a decrease in the platelet count, an increase in the blood serum liver enzymes, and reduced blood clotting ability measured as an increase in both the prothrombin (PT) and activated partial thromboplastin times (PTT). The hematocrit may be elevated. The serum urea and creatine may be raised but this is dependent on the hydration status of the patient. The bleeding time tends to be prolonged. Labs can use RT-PCR to detect the genetic material of the virus, or an ELISA test in later stages to detect antibodies produced by the immune system.
Pakistani officials also added that they had destroyed an ammunition depot and headquarters of 205 Corps brigade headquarters in Kandahar. According to Afghan local sources, Taliban were moving tanks, military equipment, and weapons from Takhar and Badakhshan to Kabul amid the conflict with Pakistan. They further add that outposts and checkpoints in parts of northern Afghanistan had been evacuated following the redeployment of Taliban forces from these areas to border regions. UN High Commissioner for Refugees (UNHCR) state that an estimated 115,000 people in Afghanistan and around 3,000 people in Pakistan have been displaced as result of border clashes. Afghans in several cities sent pictures and messages to an Afghan media outlet saying that they were threatened and forced by Taliban to participate in demonstration against Pakistan. Some Afghans in Bamyan province said local businessmen were warned that if they did not participate in the protests, "their shops would be sealed." On 6 March, armed clashes resumed along the border between Taliban forces and Pakistani border guards. Taliban officials said that they had launched an attack on Kharlachi border crossing in Dandpatan district of Paktia province, while sharing pictures of their attack. The Taliban-led Afghan Ministry of Defense said, over the previous 24 hours, Taliban forces had attacked 28 locations in the border areas of Kandahar, Nangarhar, Kunar, Khost, Paktia, and Paktika provinces, killing 109 Pakistani soldiers and injuring 148 others.
Sources: en.wikipedia.org
Paolo Bertoli (1969–1973) Luigi Raimondi (1973–1975) Corrado Bafile (1976–1980) Pietro Palazzini (1980–1988) Angelo Felici (1988–1995) Alberto Bovone (pro-prefect 1995–1998, prefect 1998) José Saraiva Martins (1998–2008) Angelo Amato (pro-prefect 2008–2010, prefect 2010–2018) Giovanni Angelo Becciu (2018 – 24 September 2020) Marcello Semeraro (2020-present)
== Clinical significance == G6PD is remarkable for its genetic diversity. Many variants of G6PD, mostly produced from missense mutations, have been described with wide-ranging levels of enzyme activity and associated clinical symptoms. Two transcript variants encoding different isoforms have been found for this gene. Glucose-6-phosphate dehydrogenase deficiency is very common worldwide, and causes acute hemolytic anemia in the presence of simple infection, ingestion of fava beans, or reaction with certain medicines, antibiotics, antipyretics, and antimalarials.
=== Inflammation and oxidative stress === In metabolic conditions like obesity and diabetes, chronic inflammation and oxidative stress drive cellular damage and insulin resistance. Semaglutide exhibits potent systemic anti-inflammatory and antioxidant properties by modulating the SIRT1 and NRF2 signaling pathways. This activation reduces the production of reactive oxygen species (ROS) and mitigates endoplasmic reticulum (ER) stress. Furthermore, semaglutide actively inhibits pro-inflammatory transcription factors such as NF-κB and JNK. In adipose tissue, it significantly decreases the infiltration of macrophages and suppresses the expression of neutrophil inflammatory factors like S100A8, S100A9, and CXCL2. Consequently, this lowers the systemic release of inflammatory cytokines like IL-6 and TNF-α.
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.
Many dried cakes are hygroscopic and can adsorb water during storage or handling. Absorbed moisture may lower the glass transition temperature and promote chemical reactions. Sealed packaging and controlled humidity reduce this risk.