A practical reference on Sublimation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-08-08 and is reviewed periodically as new material appears.
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.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common name | Freeze-drying | Process removes water by sublimation under vacuum. |
| Typical primary drying shelf temperature | -40 C to -10 C | Set below the formulation's collapse temperature. |
| Typical chamber pressure | 0.05-0.3 mbar | Low pressure allows ice to sublime below its triple point. |
| Water content after drying | 0.5-3% by weight | Higher values may reduce storage stability for some materials. |
| Key thermal parameter | Collapse temperature | Measured by freeze-drying microscopy or differential scanning calorimetry. |
Freeze-drying is distinct from simple evaporation and from spray drying. Evaporation removes water at temperatures above freezing, while spray drying rapidly dries droplets in a heated gas stream. Lyophilization avoids high temperatures, which can be useful for heat-sensitive materials such as proteins, vaccines, and some foods. The porous cake produced by sublimation dissolves or rehydrates more quickly than a dense dried mass. Not all materials tolerate freezing or the pH shifts that can occur as solutes concentrate during ice formation.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and fixes the structure of the sample. After freezing, primary drying lowers pressure so ice changes directly to vapor without passing through a liquid phase. Secondary drying then removes bound water that remains after ice sublimation. The result is a dry, porous solid that often retains its original shape.
The low pressure used during drying allows water vapor to move from the ice surface to a cold condenser. Energy supplied as heat drives sublimation but must stay below the collapse temperature of the frozen matrix. If the product becomes too warm, the frozen structure may soften or melt, reducing pore formation and slowing drying. Formulations often include bulking agents, stabilizers, or buffers to support a rigid cake. The final moisture content depends on formulation, freezing rate, and the length of secondary drying.
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.
Additionally, the heavy alkaline earth metals calcium, strontium, and barium, as well as the divalent lanthanides europium and ytterbium, are pale yellow, though the colour is much less prominent than it is for caesium. Their lustre tarnishes rapidly in air due to oxidation.
An antibody genetically engineered to neutralize myostatin, stamulumab, which was under development by pharmaceutical company Wyeth, is no longer under development. Some athletes, eager to get their hands on such drugs, turn to the internet where fake "myostatin blockers" are being sold. Resistance exercise and creatine supplementation lead to greater decreases in myostatin levels. Myostatin levels can be temporarily reduced using a cholesterol-conjugated siRNA gene knockdown.
Antimalarial medications (like hydroxychloroquine) can inhibit chemotaxis of neutrophil and eosinophil. Calcium channel blockers can be used to relax smooth muscles and decrease the resistance of the peripheral vascular system. This can help in managing Raynaud's phenomenon.
=== Length === Most classical cannabinoids are 21-carbon compounds, but variations in the side-chain length attached to the aromatic ring exist. In THC, CBD, and CBN, the side-chain is a pentyl (5-carbon) chain. Propyl (3-carbon) chain variants are named with the suffix varin (THCV, CBDV, CBNV), while heptyl (7-carbon) chain variants are named phorol (THCP, CBDP).
Sources: en.wikipedia.org
In fact, it is possible to ionize most elements with a single laser set-up, thus enabling rapid switching from one element to another. In the early days, optical schemes from RIMS have been used to study over 70 elements and over 39 elements can be ionized with a single laser combination using a rapid computer-modulated framework that switches elements within seconds.
The XM913 is an experimental American chain gun produced at Picatinny Arsenal. The cannon is a larger and more modern version of the 35 mm Bushmaster III chain gun, which itself is a larger version of the 25 mm M242 Bushmaster cannon. Although its shells, 50 x 228 mm, are twice the diameter of the 25×137mm cartridge of the M242, the 50mm cannon is not much longer than the smaller weapon. The overall lengths of the 25mm cannon and 50mm cannon are 105.2 inches (267 cm) and 117.7 inches (299 cm), respectively; while the portion of the gun that intrudes into the turret are 30.0 inches (76 cm) and 40.1 inches (102 cm), respectively. The XM913 has been selected as the primary weapon on the US Army's new Next Generation Combat Vehicle, the XM30 MICV.
Critics considered the order an effort to intimidate ICC civil servants from proceeding with its investigation and accused the administration of targeting the two prosecutors, both of African origin, based on their race. The U.S. District Court for the Southern District of New York granted a preliminary injunction blocking the sanctions in January 2021, through a challenge to the order brought by four dual-national American law professors and the Open Society Justice Initiative. (The Biden administration lifted the ICC sanctions in April 2021.) Also in September 2020, Trump used the IEEPA to order the removal of social media platforms TikTok and WeChat from U.S. app stores as well as prohibit domestic business transactions involving their respective China-based parent companies ByteDance and Tencent; the restrictions would have become applicable to TikTok unless it was sold to an American company within 45 days of the executive order's issuance. Observers (including Trump administration critics and many TikTok users) raised First Amendment concerns with the executive order and suggested that, while national security concerns were cited to justify them, the sanctions were prompted by the administration's hostile relations toward China in general and retaliation against TikTok in particular. This retaliation was claimed to be for certain anti-Trump content hosted by the app.
The subject was said to have “agrypnia excitata”, which consists of severe total insomnia of long duration associated with decreased vigilance, mental confusion, hallucinations, motor agitation, and complex motor behavior mimicking dreams, and autonomic activation. CNS and autonomic symptoms were caused by impaired corticolimbic control of the subcortical structures regulating the sleep-wake and autonomic functions.
== M == Maillard reaction Madelung synthesis Malaprade reaction, Periodic acid oxidation Malonic ester synthesis Mannich reaction Markó–Lam deoxygenation Markovnikov's rule, Markownikoff rule, Markownikow rule Marschalk reaction Martinet dioxindole synthesis McDougall monoprotection McFadyen–Stevens reaction McMurry reaction Meerwein arylation Meerwein–Ponndorf–Verley reduction Meisenheimer rearrangement Meissenheimer complex Menshutkin reaction Metal-ion-catalyzed σ-bond rearrangement Mesylation Merckwald asymmetric synthesis Metallo-ene reaction Methylation Meyer–Hartmann reaction Meyer reaction Meyer synthesis Meyer–Schuster rearrangement Michael addition Michael addition, Michael system Michael condensation Michaelis–Arbuzov reaction Midland Alpine borane reduction Mignonac reaction Milas hydroxylation of olefins Minisci reaction Mislow–Evans rearrangement Mitsunobu reaction Miyaura borylation Modified Wittig-Claisen tandem reaction Molisch's test Mozingo reduction Mukaiyama aldol addition (Mukaiyama reaction) Mukaiyama hydration Myers' asymmetric alkylation
Sources: en.wikipedia.org
== Adverse effects == Adverse effects include drowsiness, dizziness, weakness, fatigue, headache, trouble sleeping, nausea and vomiting, poor concentration and recall (resembling dementia), urinary retention, or constipation.
Olipudase alfa, sold under the brand name Xenpozyme, is a medication used for the treatment of non-central nervous system (CNS) manifestations of acid sphingomyelinase deficiency type A/B or type B. The most common side events include infections, infusion-related reactions, or gastrointestinal complaints (disease signs and symptoms in children). Historically referred to as Niemann-Pick disease types A (NPD A) and B (NPD B), acid sphingomyelinase deficiency is a genetic disorder. It belongs to the larger family of metabolic disorders called lysosomal storage diseases, in which fats build up within the parts of the body's cells that break down nutrients and other materials. This affects the way cells work and causes them to die, affecting normal functioning of tissues and organs. Acid sphingomyelinase deficiency is seriously debilitating and life-threatening since the build-up of fatty substances can cause brain damage and swelling of organs such as liver and spleen. Xenpozyme is the first acid sphingomyelinase deficiency-specific treatment. The replacement enzyme is produced by a method known as recombinant DNA technology: it is made by cells into which a gene (DNA) has been introduced, that enables them to produce the enzyme. Olipudase alfa was approved for medical use in Japan in March 2022, in the European Union in June 2022, and in the United States in August 2022. The US Food and Drug Administration (FDA) considers it to be a first-in-class medication.
===== Europe ===== In 1997, European Union health ministers voted to ban avoparcin and four additional antibiotics used to promote animal growth in 1999. In 2006, a ban on the use of antibiotics in European feed, with the exception of two antibiotics in poultry feeds, became effective. In Scandinavia, there is evidence that the ban has led to a lower prevalence of antibiotic resistance in (nonhazardous) animal bacterial populations. As of 2004, several European countries established a decline of antimicrobial resistance in humans through limiting the use of antimicrobials in agriculture and food industries without jeopardizing animal health or economic cost.
By the second half of the 1800s, the scientific study of psychology was becoming well established in university laboratories. Although there were a few scattered voices calling for applied psychology, the general field looked down upon this idea and insisted on "pure" science as the only respectable practice. This changed when Lightner Witmer (1867–1956), a past student of Wundt and head of the psychology department at the University of Pennsylvania, agreed to treat a young boy who had trouble with spelling. His successful treatment was soon to lead to Witmer's opening of the first psychological clinic at Penn in 1896, dedicated to helping children with learning disabilities. Ten years later in 1907, Witmer was to found the first journal of this new field, The Psychological Clinic, where he coined the term "clinical psychology", defined as "the study of individuals, by observation or experimentation, with the intention of promoting change". The field was slow to follow Witmer's example, but by 1914, there were 26 similar clinics in the US. Even as clinical psychology was growing, working with issues of serious mental distress remained the domain of psychiatrists and neurologists. However, clinical psychologists continued to make inroads into this area due to their increasing skill at psychological assessment. Psychologists' reputation as assessment experts became solidified during World War I with the development of two intelligence tests, Army Alpha and Army Beta (testing verbal and nonverbal skills, respectively), which could be used with large groups of recruits.
Naloxegol (INN; PEGylated naloxol; trade names Movantik and Moventig) is a peripherally acting μ-opioid receptor antagonist developed by AstraZeneca, licensed from Nektar Therapeutics, for the treatment of opioid-induced constipation. It was approved in 2014 in adult patients with chronic, non-cancer pain. Doses of 25 mg were found safe and well tolerated for 52 weeks. When given concomitantly with opioid analgesics, naloxegol reduced constipation-related side effects, while maintaining comparable levels of analgesia. The most common side effects are abdominal pain, diarrhea, nausea, flatulence, vomiting, and headache. Naloxegol was previously a Schedule II drug in the United States because of its chemical similarity to noroxymorphone. It was officially decontrolled in January 2015. It was reclassified as a prescription drug after the FDA and DEA concluded that the impermeability of the blood–brain barrier to this compound made it non-habit-forming, and so without the potential for abuse.
Sources: en.wikipedia.org
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.
Freezing determines ice crystal size, pore structure, and the concentration of solutes in remaining liquid. Faster freezing generally creates smaller ice crystals and a denser dried matrix. These features affect drying rate and reconstitution behavior.
Lyophilization reduces water content but usually leaves a small amount of water in the dried material. Some water remains bound to solids or trapped in the dried matrix. Very low water targets can require extended secondary drying, which may alter product stability.
Lyophilized products should be stored in airtight containers, protected from moisture and light, at the temperature specified by the manufacturer. Many require refrigeration at 2–8 °C, while some need frozen storage. Always check the product label for specific conditions.