Moisture sorption raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-05-05. Anything still debated is marked as such rather than presented as settled.
Analytical methods for lyophilized materials include X-ray diffraction for crystallinity, differential scanning calorimetry for thermal transitions, and scanning electron microscopy for pore morphology. Moisture sorption analysis shows how the cake responds to humidity. These methods help distinguish amorphous from crystalline states and detect phase changes. Open questions remain about how pore structure changes during long-term storage and how best to predict collapse under varied conditions. Comparisons across studies are complicated by differences in formulation, cycle, and storage history.
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.
A typical cycle begins with freezing, sometimes including an annealing step to control ice crystal size. Freezing conditions influence the pore network that later allows vapor escape. During primary drying, shelf temperature and chamber pressure are set so heat enters the product while its temperature stays below the collapse or eutectic point. Secondary drying then raises the shelf temperature to desorb bound water and lower residual moisture. Cycle design depends on formulation, fill volume, container type, and equipment capability.
The physics of lyophilization couples heat transfer, mass transfer, and phase behavior. Sublimation requires a vapor pressure difference between the ice front and the chamber, and the dried layer adds resistance to vapor flow. Amorphous formulations are characterized by a glass transition temperature of the maximally freeze-concentrated solute, often denoted Tg'. Crystalline bulking agents can provide structure, while amorphous excipients stabilize labile components. Open questions remain about spatial heterogeneity, edge effects, and how laboratory cycles scale to production.
Lyophilization is a drying process in which a solvent, usually water, is removed from a frozen material by sublimation under reduced pressure. The material is first solidified, then placed under vacuum so that ice transitions directly to vapor without a bulk liquid phase. This approach suits heat-sensitive substances that would degrade during conventional evaporation. Primary drying removes unbound ice, while secondary drying reduces water that remains adsorbed to the solid matrix. The result is a porous, lightweight solid that can be reconstituted later.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white porous cake | Color and texture vary with formulation. |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity, excipients, and diluent. |
| Typical moisture level | 0.5-3% w/w | Lower values suit hydrolysis-sensitive materials. |
| Common moisture method | Karl Fischer titration | Coulometric mode is common for low water levels. |
| Typical storage temperature | 2-8 °C or ambient | Some products require frozen storage; protect from humidity. |
=== Precautions === Pioglitazone/metformin should not be used in people with type 1 diabetes or for the treatment of diabetic ketoacidosis and should be used with caution in people with edema. Serum ALT levels should be evaluated prior to the initiation of therapy with combination of pioglitazone and metformin and periodically thereafter per the clinical judgment of the health care professional.
According to a February 2015 Newsweek report, Houthis are fighting "for things that all Yemenis crave: government accountability, the end to corruption, regular utilities, fair fuel prices, job opportunities for ordinary Yemenis and the end of Western influence". In forming alliances, the Houthi movement has been at times opportunistic, partnering with countries it later declared as enemies, including the United States. The influx of various individual and tribal interests has somewhat diluted the movement's original vision over time. Around the time of the third Saada war (November 2005–February 2006), the conflict was increasingly waged "along the lines of prevalent tribal feuds", which distorted the initial socio-economic, religious and ideological aims of Hussein al-Houthi.
== Philanthropy == Gallwas met Beckman Instruments founder Dr. Arnold Beckman and his wife, Mabel, within a few weeks of joining the company. Their friendship led to Gallwas' 40-year affiliation with the Arnold and Mabel Beckman Foundation. Gallwas is credited with collecting and displaying Arnold Beckman's earliest inventions that helped launch the electronic revolution in the chemical and biological sciences. The inventions are displayed at the Arnold and Mabel Beckman Center of the National Academies of Science and Engineering in Irvine, CA. Additional exhibits that Gallwas collected are housed at the Chemical Heritage Foundation, now the Science History Institute in Philadelphia and at the Beckman Institute for Advanced Science and Technology at the University of Illinois at Urbana Champaign.
In 1897 he put forward the idea to create the International Atomic Weights Commission. Fischer was elected a Foreign Member of the Royal Society (ForMemRS) in 1899. He was awarded the 1902 Nobel Prize in chemistry "in recognition of the extraordinary services he has rendered by his work on sugar and purine syntheses." He was elected an International Member of the United States National Academy of Sciences in 1904, an International Honorary Member of the American Academy of Arts and Sciences in 1908, and an International Member of the American Philosophical Society in 1909. Many names of chemical reactions and concepts are named after him:
Sources: en.wikipedia.org
== Medical uses == Tafasitamab, in combination with lenalidomide, is indicated for the treatment of adults with relapsed or refractory diffuse large B-cell lymphoma. In the EU, tafasitamab (Minjuvi) is indicated in combination with lenalidomide followed by tafasitamab monotherapy for the treatment of adults with relapsed or refractory diffuse large B-cell lymphoma who are not eligible for autologous stem cell transplant. In June 2025, the US Food and Drug Administration (FDA) expanded the indication for tafasitamab, in combination with lenalidomide and rituximab, for adults with relapsed or refractory follicular lymphoma.
== Price fixing investigation == It is known whether this apparent price fixing is actively being investigated, but the United States Department of Justice Antitrust Division Spring Update 2021 notes: "The Division remains committed to rooting out illegal conduct that corrupts critical healthcare markets. That work is more important now than ever before. The Division has uncovered price-fixing, bid-rigging, and customer-allocation schemes in one of the most important markets for the health and wallets of American consumers: the generic drug industry. Indeed, nearly 90% of all prescriptions in the United States are filled with generic drugs."
=== Medicine and materials === Phytochemistry is a branch of plant biochemistry primarily concerned with the chemical substances produced by plants during secondary metabolism. Some of these compounds are toxins such as the alkaloid coniine from hemlock. Others, such as the essential oils peppermint oil and lemon oil are useful for their aroma, as flavourings and spices (e.g., capsaicin), and in medicine as pharmaceuticals as in opium from opium poppies. Many medicinal and recreational drugs, such as tetrahydrocannabinol (active ingredient in cannabis), caffeine, morphine and nicotine come directly from plants. Others are simple derivatives of botanical natural products. For example, the pain killer aspirin is the acetyl ester of salicylic acid, originally isolated from the bark of willow trees, and a wide range of opiate painkillers like heroin are obtained by chemical modification of morphine obtained from the opium poppy. Popular stimulants come from plants, such as caffeine from coffee, tea and chocolate, and nicotine from tobacco. Most alcoholic beverages come from fermentation of carbohydrate-rich plant products such as barley (beer), rice (sake) and grapes (wine). Native Americans have used various plants as ways of treating illness or disease for thousands of years. This knowledge Native Americans have on plants has been recorded by enthnobotanists and then in turn has been used by pharmaceutical companies as a way of drug discovery.
Sources: en.wikipedia.org
== Commemoration == In November 1927, Thomson opened the Thomson building, named in his honour, in the Leys School, Cambridge. In 1991, the thomson (symbol: Th) was proposed as a unit to measure mass-to-charge ratio in mass spectrometry in his honour. J J Thomson Avenue, on the University of Cambridge's West Cambridge site, is named after Thomson. The Thomson Medal Award, sponsored by the International Mass Spectrometry Foundation, is named after Thomson. The Institute of Physics Joseph Thomson Medal and Prize is named after Thomson. Thomson Crescent in Deep River, Ontario, connects with Rutherford Ave.
== Treatment == Levonantradol has been clinically tested in cancer patients for its pain relief and antiemetic benefits. Cancer patients that endure chemotherapy often develop intense nausea, and Levonantradol has been tested to reduce these emetic symptoms. It is often used instead of THC because it has a higher efficacy. Levonantradol also acts on pain pathways in the central nervous system, which enables the drug to alleviate pain. Studies have shown an absence of emetic side effects within the half-life of the Levonantradol administered. Other studies suggest that cannabinoid agonists can synergize opioid anti-nociception. Cannabinoid receptors are located in nociceptive pathways, and CBs can promote signal transduction in TRP channels. Although Levonantradol relieves nociceptive and postoperative pain, decreases nausea, and improves spasticity in addition to being more effective than placebos, it has yet to be approved as legal medicine. Researchers have concluded that Levonantradol is no more effective than Codeine, which is why they do not recommend expansion into clinical practice.
Around the time, an expert concludes that "AI art is everywhere right now", with even experts not knowing what it will mean, a news outlet establishes that "AI-generated art booms" and reports about issues of copyright and automation of professional artists, a news outlet investigates how online communities (e.g. their rules) confronted with many such artworks react, a news outlet raised concerns over deepfakes, a magazine highlights possibilities of enabling "new forms of artistic expression", an editorial notes that it may be seen as a welcome "augmentation of human capability". Moreover, additional functionalities – such as enabling the use of user-provided concepts (like an object or a style) learned from few images for novel personalized art generated from the associated word/s (2 Aug) or expanding beyond the borders of artistic images in the same style (31 Aug) – are reported. On 22 August, Stable Diffusion is released as free and open source software.
R2NH + R'C(O)Cl + (CH3CH2)3N → R'C(O)NR2 + [(CH3CH2)3NH]+Cl− Like other tertiary amines, it catalyzes the formation of urethane foams and epoxy resins. It is also useful in dehydrohalogenation reactions and Swern oxidations. Triethylamine is readily alkylated to give the corresponding quaternary ammonium salt:
Sources: en.wikipedia.org
Karl Fischer titration is a common method, using coulometric or volumetric detection. Thermogravimetric analysis can also measure weight loss on heating. Results depend on sample handling because the dried solid can absorb moisture quickly.
The porous cake readily absorbs water vapor from air, which can reduce stability or cause collapse. Vials are sealed with stoppers and crimp seals, sometimes under vacuum or inert gas. Packaging also protects against oxygen and mechanical damage.
Collapse occurs when the product temperature rises above its collapse threshold during primary drying. The ice matrix loses structure, and the cake may shrink or melt back. Formulation excipients and freezing rate influence collapse threshold.
Freezing only converts liquid to solid. Lyophilization adds vacuum and controlled warming so frozen solvent sublimes, leaving a dry porous solid. The two steps are related but not interchangeable.