Moisture sorption comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-07-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
After lyophilization, a product's quality depends on residual moisture, cake appearance, and reconstitution time. Residual moisture is often measured by Karl Fischer titration or thermogravimetric analysis. A low moisture content can slow chemical degradation, but overly dry cakes may be brittle or slow to dissolve. Stability studies track these attributes over months under defined temperature and humidity conditions. Batch records link these measurements to specific process runs and help identify trends before a product fails specification.
Storage conditions for dried products usually aim to exclude moisture and oxygen. Vials are sealed under vacuum or with an inert gas, and stoppers must maintain a barrier during transport. Temperature recommendations vary; some materials remain stable at room temperature, while others need refrigeration or frozen storage. Humidity control is critical because dried cakes can absorb water rapidly once a container is opened. Desiccant packs and moisture-barrier bags add further protection during shipping.
Stability studies examine how temperature, humidity, and time influence a lyophilized product. Accelerated conditions provide early information about degradation pathways, while long-term studies support shelf-life claims. The glass transition temperature of the dried formulation can indicate its physical stability, and storage above this temperature may increase molecular mobility and lead to collapse or aggregation. Container closure integrity also matters because moisture or oxygen ingress can degrade the product, so vial stoppers and seals are part of the quality system.
Handling and storage practices aim to keep the cake intact and dry. Vials are typically stored upright at controlled temperatures, often between 2 °C and 8 °C or at -20 °C for longer-term use. Reconstitution involves adding a suitable diluent and gently mixing until the solid dissolves. Shaking or rapid injection of diluent can create foam or damage sensitive molecules. Once reconstituted, the product may require refrigeration and use within a defined period.
Residual moisture is a key quality attribute for lyophilized products. Water that remains after secondary drying can affect chemical stability, cake structure, and shelf life. Karl Fischer titration is a common method for measuring water content in the dried solid. The target range varies by product, but many biologics are dried to between 0.5% and 3% water by weight. Acceptable limits are set during development and confirmed by stability studies.
| Property | Value | Notes |
|---|---|---|
| Appearance | Porous solid cake | Typically white to off-white; varies with formulation |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity and solute |
| Residual moisture | 0.5-3% w/w | Measured by Karl Fischer titration |
| Storage temperature | Room temperature to -20 °C | Product-specific; humidity-controlled |
| Common quality attribute | Cake elegance | Visual check for collapse, shrinkage, or meltback |
After drying, a lyophilized product is usually sealed under vacuum or an inert gas to limit moisture and oxygen exposure. The container closure system matters because stoppers and seals can allow moisture ingress over time. Storage conditions are selected from stability studies that track potency, cake appearance, and reconstitution behavior. Many freeze-dried materials are kept at controlled room temperature, while some require refrigeration or protection from light.
Quality control for freeze-dried forms includes visual inspection, water content measurement, and reconstitution time. A satisfactory cake is typically uniform, porous, and intact, although minor shrinkage or cracking may be acceptable if specifications allow. Karl Fischer titration, thermal gravimetric analysis, and near-infrared spectroscopy are used to measure water content. Reconstitution is assessed by adding a specified diluent and recording the time and ease of dissolution. Microbiological and particulate tests are added when the product is sterile or intended for injection.
Stability of a lyophilized solid depends on water content, temperature, and the physical state of the formulation. Amorphous products may slowly absorb moisture and drop below their glass transition temperature, causing collapse or crystallization. Some proteins and peptides can aggregate even in a dry state, especially when exposed to heat or moisture. Accelerated stability studies at elevated temperature and humidity help estimate shelf life, but real-time data remain the basis for expiration dating.
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.
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.
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.
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.
Gone with the Wind itself may have been briefly overtaken by The Ten Commandments (1956), which closed at the end of 1960 with worldwide rentals of $58–60 million compared to Gone with the Wind's $59 million; if it did claim the top spot its tenure there was short-lived, since Gone with the Wind was re-released the following year and increased its earnings to $67 million. Depending on how accurate the estimates are, the 1959 remake of Ben-Hur may also have captured the record from Gone with the Wind: as of the end of 1961 it had earned $47 million worldwide, and by 1963 it was trailing Gone with the Wind by just $2 million with international takings of $65 million, ultimately earning $66 million from its initial release.
=== Composition === The Composition C-4 used by the United States Armed Forces contains 91% RDX ("Research Department Explosive", an explosive nitroamine), bound by a mixture of 5.3% dioctyl sebacate (DOS) or dioctyl adipate (DOA) as the plasticizer (to increase the plasticity of the explosive), thickened with 2.1% polyisobutylene (PIB, a synthetic rubber) as the binder, and 1.6% of a mineral oil often called "process oil". Instead of "process oil", low-viscosity motor oil is used in the manufacture of C-4 for civilian use. The British PE4 consists of 88.0% RDX, 1.0% pentaerythrite dioleate and 11.0% DG-29 lithium grease (corresp. to 2.2% lithium stearate and 8.8% mineral oil BP) as the binder; a taggant (2,3-dimethyl-2,3-dinitrobutane, DMDNB) is added at a minimum of 0.10% weight of the plastic explosive, typically at 1.0% mass. The newer PE7 consists of 88.0% RDX, 1.0% DMDNB taggant and 11.0% of a binder composed of low molecular mass hydroxyl-terminated polybutadiene, along with an antioxidant and an agent preventing hardening of the binder upon prolonged storage. The PE8 consists of 86.5% RDX, 1.0% DMDNB taggant and 12.5% of a binder composed of di(2-ethylhexyl) sebacate thickened with high molecular mass polyisobutylene. Technical data according to the Department of the Army for the Composition C-4 follows.
=== Use of meloxicam in cats === The issue of using meloxicam in cats involves conflicting guidelines, differing legislation, and a narrow therapeutic safety margin that can easily turn the drug from cure to poison. More specifically:
14 March Members of the NASUWT narrowly vote to accept a pay offer, ending the prospect of further strike action in schools in Scotland. BBC Scotland hosts the final televised debate of the SNP leadership election. 16 March – Scientists identify a gene variant that is known to increases the risk of breast and ovarian cancer, and trace it to people with Orkney Island heritage, more specifically those with ancestry on the island of Westray. 18 March – Peter Murrell resigns as chief executive of the Scottish National Party amid a row over party membership. Mike Russell succeeds him as interim chief executive. 21 March – At 8pm, Times Radio airs a leadership debate from Edinburgh and featuring the three candidates in the Scottish National Party leadership election. 22 March First Minister Nicola Sturgeon issues a "sincere, heartfelt and unreserved" apology to people affected by the practice of forced adoption in Scotland during the 1950s, 1960s and 1970s. A major incident is declared, with 35 injuries reported, after the 76m-long RV Petrel research vessel tips over at a dock in Leith. 23 March Nicola Sturgeon attends her final First Minister's Questions as First Minister of Scotland. The TikTok app is banned on all Scottish Government phones and electronic devices. 24 March – Research led by the University of Edinburgh suggests one in 50 people in Scotland have had lasting ill-effects after contracting COVID-19. 25 March – HIV Scotland announces it will close due to issues with governance and financials.
Sources: en.wikipedia.org
=== First modular space station === The USSR turned its space program to the development of the low Earth orbit modular space station Mir (peace or world) assembled in orbit from 1986 to 1996. At 129,700 kilograms (285,900 lb), it held records for the largest spacecraft and the longest continuous human presence in space at 3,644 days, until the International Space Station was built starting in 1998. Mir's operation continued after the 1991 replacement of the USSR's space program with the Russian Federal Space Agency until 2001, supported by Soyuz spacecraft.
However, Karachi-based K-Electric and Water and Power Development Authority (WAPDA) generate much of the electricity used in Pakistan and collect revenue nationwide. In 2023, Pakistan's installed electricity generation capacity was ~45,885 MWt. Pakistan produced 1,135 megawatts of renewable energy for the month of October 2016. Pakistan expects to produce 10,000 megawatts of renewable energy by 2025.
In Iceland, flunitrazepam is a controlled substance available from Mylan. It is prescribed for severe insomnia and is sometimes used before surgery to induce a calm, relaxed state of mind for the patient. In Sweden, flunitrazepam is a List II drug (substances with medicinal uses) under the Narcotics Control Act (1968). It was previously available from Mylan, but has been removed from the market in January 2020. In the United Kingdom, flunitrazepam is not licensed for medical use and is a controlled drug under Schedule 3 and Class C. In the United States, the drug has not been approved by the Food and Drug Administration and is considered to be an illegal drug; as of 2016 it is Schedule IV. 21 U.S.C. § 841 and 21 U.S.C. § 952 provide for punishment for the importation and distribution of up to 20 years in prison and a fine; possession is punishable by three years and a fine. Travelers travelling into the United States are limited to a 30-day supply. The drug must be declared to US Customs upon arrival. If a valid prescription cannot be produced, the drug may be subject to Customs search and seizure, and the traveler may face criminal charges or deportation.
Sources: en.wikipedia.org
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the intermediate liquid state. The verb form of sublimation is sublime, or less preferably, sublimate. Sublimate also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly (for definition, see below) is called critical sublimation point, or simply, sublimation point. Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating. The reverse process of sublimation is deposition (also called desublimation), in which a substance passes directly from a gas to a solid phase, without passing through the intermediate liquid state. Technically, all solids may sublime, though most sublime at extremely low rates that are hardly detectable under usual conditions. At normal pressures, most chemical compounds and elements possess three different states at different temperatures. In these cases, the transition from the solid to the gas state requires an intermediate liquid state. The pressure referred to is the partial pressure of the substance, not the total (e.g. atmospheric) pressure of the entire system. Thus, any solid can sublime if its vapour pressure is higher than the surrounding partial pressure of the same substance, and in some cases, sublimation occurs at an appreciable rate (e.g. water ice just below 0 °C).
== Internal angle bisectors and incenter == The internal angle bisectors are segments in the interior of the triangle reaching from one vertex to the opposite side and bisecting the vertex angle into two equal angles. The angle bisectors ta etc. satisfy
short arm Denoted in shorthand with the symbol p. In condensed chromosomes where the positioning of the centromere creates two segments or "arms" of unequal length, the shorter of the two arms of a chromatid. Contrast long arm.
== Diet == Like other blowflies, C. vomitoria colonize animal remains, including humans. While adult C. vomitoria feed on nectar, the larvae feed on corpses, the medium in which they grow. However, it has been shown that feeding on processed substrates (food that are modified for human consumption by increasing shelf life and taste through salting, curing, smoking, etc.) provided much better growth than unprocessed substrates such as raw unmodified liver. Because different substrates drastically affected growth, C. vomitoria is best characterized as a specialist that best utilizes processed substrates (minced meats, for example). Its close relative, Calliphora vicina, is a generalist, being able to utilize mixed substrates with equal growth rates. In the case of overcrowding, C. vomitoria competition results in compensation by increased speed of development, leading to smaller larvae and adults. This has complications in forensics because different parts of the body would grow at different rates. Additionally, it has been shown that the fly larvae are able to colonize even buried remains. Growth rates are similar between surface and buried larvae. Usually, these flies lay their eggs around wounds on fresh corpses shortly after death. Right before the pupal stage, the fly larvae that leaves the carrion can burrow into the soil in order to pupate. Then, adult flies emerge. In decaying carcasses, it was found that Calliphoridae flies dominate, especially C. vomitoria. In both spring and fall, C. vomitoria is the primary species found on carcasses. In some cases, C.
Sources: en.wikipedia.org
Karl Fischer titration is a common reference method that quantifies water by a chemical reaction. Thermogravimetric analysis can also estimate moisture by weight loss on heating. Method choice depends on sample size and whether other volatile substances are present.
Cake collapse often occurs when the product exceeds its collapse temperature during primary drying. The frozen matrix loses structure and the ice channels close. Optimizing formulation and cycle parameters helps avoid this defect.
No. Storage temperature depends on the stability of the dried material. Some products are stable at room temperature, while others require refrigeration or freezing. Container integrity and moisture barriers also affect shelf life.
Residual moisture can influence chemical degradation, cake collapse, and long-term stability. Low moisture levels usually improve stability, but each product has an optimal range.