This is a working overview of Secondary drying, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
After lyophilization, the dried product is often sealed under vacuum or an inert gas to limit moisture and oxygen exposure. Vials, stoppers, and seals must maintain their barrier throughout shelf life. Storage temperature depends on product sensitivity: some cakes tolerate controlled room temperature, while labile biologics require refrigeration. Humidity is a critical variable because dried cakes are hygroscopic and can absorb water when exposed to air. Handling procedures therefore limit open-vial time and use desiccated environments for sampling.
Quality control for lyophilized materials examines appearance, reconstitution time, residual moisture, and mechanical integrity. An acceptable cake is usually uniform and porous, though appearance alone does not prove stability. Karl Fischer titration is a common method for water content, while differential scanning calorimetry can reveal glass transition events. Stability studies track potency, aggregation, and moisture over time under defined temperature and humidity conditions. Specifications are product-specific and may include sterility and endotoxin tests for sterile preparations.
| Property | Value | Notes |
|---|---|---|
| Process name | Lyophilization or freeze-drying | Both terms appear in technical standards and literature. |
| Phase transition | Sublimation | Solid ice becomes vapor without a liquid step. |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product temperature and equipment. |
| Typical product temperature | -40 °C to -10 °C | Measured during primary drying; formulation sets limits. |
| Water content after drying | 0.5-3% w/w | Target varies by material and stability needs. |
=== Oral GLP-1 Semaglutide Generic === SCD has been developing an oral generic version of semaglutide, the active ingredient in Novo Nordisk's Wegovy and Ozempic. In January 2026, SCD signed a partnership agreement with Daiichi Sankyo Espha, a subsidiary of Japan's Daiichi Sankyo, for the exclusive sale of oral semaglutide generics in Japan. Some industry observers and analysts have questioned the company's public statements regarding this product. A commentary published by the Korea Biomedical Review in July 2025 noted that SCD's claims of a potential 2026 market launch for its oral semaglutide generic appeared to overstate the company's regulatory position, given that secondary patents on semaglutide formulations are widely expected to remain in force until at least 2031 in most major markets.
=== Infection === TPN requires a chronic IV access for the solution to run through, and the most common complication is infection of this catheter. Infection is a common cause of death in these patients, with a mortality rate of approximately 15% per infection, and death usually results from septic shock. When using central venous access, the subclavian (or axillary) vein is preferred due to its ease of access and lowest infectious complications compared to the jugular and femoral vein insertions. Catheter complications include pneumothorax, accidental arterial puncture, and catheter-related sepsis. The complication rate at the time of insertion should be less than 5%. Catheter-related infections may be minimised by appropriate choice of catheter and insertion technique.
In 2019, the Economist Intelligence Unit's biannual Worldwide Cost of Living survey ranked Moscow 102nd among the 133 most expensive cities. ECA International's Cost of Living 2019 Survey ranked Moscow 120th among 482 locations globally.
Sources: en.wikipedia.org
Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). These conditions occur largely as a consequence of aging, but may also be the result of congenital (inborn) abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy. Anatomically, the valves are part of the dense connective tissue of the heart known as the cardiac skeleton and are responsible for the regulation of blood flow through the heart and great vessels. Valve failure or dysfunction can result in diminished heart functionality, though the particular consequences are dependent on the type and severity of valvular disease. Treatment of damaged valves may involve medication alone, but often involves surgical valve repair or valve replacement.
== Expression and possible function == FAP expression under physiological conditions is very low in the majority of adult tissues. FAP is nevertheless expressed during embryonic development, and in adults in pancreatic alpha cells in multipotent bone marrow stromal cells (BM-MSC) and uterine stroma. FAP expression is high in reactive stromal fibroblasts of epithelial cancers, granulation tissue of healing wounds, and malignant cells of bone and soft tissue sarcomas. FAP is thought to be involved in the control of fibroblast growth or epithelial-mesenchymal interactions during development, tissue repair, and epithelial carcinogenesis. Fibroblast activation protein (FAP) is overexpressed in a vast majority of neoplasms, particularly in more than 90% of epithelial tumors which could be an appropriate target for evaluation of tumor’s molecular and metabolic functions by FAP inhibitor (FAPI) ligands
=== Limitations of non-invasive electrical and magnetic methods === Brain tissue stimulation using non-invasive electrical and magnetic methods raises several concerns, including the following: The first issue is the uncertain dose for healthy stimulation. While neurophysiology lacks knowledge about the nature of such a treatment of nervous diseases at the cellular level, non-invasive electrical and magnetic therapies involve excessive exposure of the brain to an intense field, which is several times and even orders of magnitude higher than natural electromagnetic fields in the brain. Another significant challenge of non-invasive electrical and magnetic methods is to localize the effect of stimulation on specific neuronal networks that need to be treated. We still need to gain knowledge about mental processes at the cellular level. Neuronal correlates of cognitive functions are still intriguing questions for contemporary research. Non-invasive electrical and magnetic brain tissue stimulation targets a large area of poorly characterized tissue. Therefore, it is unclear whether electrical and magnetic fields reach only the neuronal networks of the brain that need treatment. Again, these methods involve excessive exposure to intense electrical and magnetic fields several times and even orders of magnitude higher than natural ones in the brain. However, non-invasive electrical and magnetic brain tissue methods cannot target only the neuronal networks that need to be treated. The undefined radiation target can destroy healthy cells during therapy.
Sources: en.wikipedia.org
H2O + ATP → H+ + ADP + Pi (Mg2+ assisted, utilization of ATP for Muscle contraction by ATPase) H+ + ADP + CP → ATP + Creatine (Mg2+ assisted, catalyzed by creatine kinase, ATP is used again in the above reaction for continued muscle contraction) 2 ADP → ATP + AMP (catalyzed by adenylate kinase/myokinase when CP is depleted, ATP is again used for muscle contraction) Muscle at rest:
The president of Serbia and Montenegro (Serbian: Предс(ј)едник Србије и Црне Горе, romanized: Preds(j)ednik Srbije i Crne Gore) was the head of state of Serbia and Montenegro. From its establishment in 1992 until 2003, when the country was reconstituted as a confederacy (state union) via constitutional reform, the head of state was known as the president of the Federal Republic of Yugoslavia (Serbian: Предс(ј)едник Савезне Републике Југославије, romanized: Preds(j)ednik Savezne Republike Jugoslavije). With the constitutional reforms of 2003 and the merging of the offices of head of government and head of state, the full title of the president was President of Serbia and Montenegro and Chairman of the Council of Ministers of Serbia and Montenegro (Serbian: Предс(ј)едник Србије и Црне Горе / Предс(ј)едник Сав(ј)ета министара Србије и Црне Горе). In 2006 the office was abolished as the state union was dissolved, with Serbia and Montenegro becoming independent countries.
== Further reading == Sigel, Astrid; Freisinger, Eva; Sigel, Roland K.O., eds. (2020). Transition Metals and Sulfur: A Strong Relationship for Life. Guest Editors Martha E Sosa Torres and Peter M.H.Kroneck. Berlin/Boston: de Gruyter. pp. xlv+455. ISBN 978-3-11-058889-7.
The preferred, native cleavage sequence was first identified by examining the cut sites in the native polyprotein substrate for recurring sequence. The consensus for these native cut sites is ENLYFQ\S where '\' denotes the cleaved peptide bond. Residues of the substrate are labelled P6 to P1 before the cut site and P1' after the cut site. Early works also measured cleavage of an array of similar substrates to characterise how specific the protease was for the native sequence. Studies have subsequently used sequencing of cleaved substrates from a pool of randomised sequences to determine preference patterns. Although ENLYFQ\S is the optimal sequence, the protease is active to a greater or lesser extent on a range of substrates (i.e. shows some substrate promiscuity). The highest cleavage is of sequences closest to the consensus EXLYΦQ\φ where X is any residue, Φ is any large or medium hydrophobe and φ is any small hydrophobic or polar residue. Although this sequence is the optimal, sequences with disfavoured residues at some positions can still be cleaved if the rest of the sequence is optimal. Specificity is endowed by the large contact area between enzyme and substrate. Proteases such as trypsin have specificity for one residue before and after the cleaved bond due to a shallow binding cleft with only one or two pockets that bind the substrate side chains. Conversely, viral proteases such as TEV protease have a long C-terminal tail which completely covers the substrate to create a binding tunnel.
Sources: en.wikipedia.org
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.
Lowering pressure reduces the boiling point of water and allows ice to sublimate at temperatures below freezing. Vacuum also limits convective heat transfer, so heat is usually supplied by shelves or radiation. The pressure must stay below the vapor pressure of ice at the product temperature.
The cycle typically includes freezing, primary drying, and secondary drying. Freezing solidifies water and sets the pore structure; primary drying removes bulk ice; secondary drying removes bound water. Some cycles add annealing or pre-freezing steps.
No. Freeze-drying removes water but does not reliably kill microorganisms. Sterile lyophilized products are typically prepared aseptically before freezing or are sterilized by a validated method. Microbial control depends on the entire manufacturing process.