The short version of Moisture sorption fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-12-31 and is reviewed periodically as new material appears.
Quality control for lyophilized materials includes visual inspection, residual moisture measurement, and reconstitution testing. Cake appearance can reveal process problems such as collapse, shrinkage, or meltback, although appearance alone does not prove potency. Residual moisture is commonly measured by Karl Fischer titration or by loss on drying. Reconstitution time is checked because a slow or incomplete dissolve can indicate a change in pore structure. Stability studies track these attributes over time under defined temperature and humidity conditions.
Analytical methods for lyophilized solids must account for the low moisture content and the fragile cake. Karl Fischer titration is widely used for water content, while near-infrared spectroscopy can measure moisture non-destructively in sealed containers. X-ray diffraction and modulated differential scanning calorimetry help identify crystalline or amorphous phases. Residual solvent analysis may be needed if organic solvents were used during formulation. The combination of these methods supports batch release and long-term stability assessment.
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.
| Property | Value | Notes |
|---|---|---|
| Storage temperature | 2–8 °C or 20–25 °C | Depends on product stability; some require frozen storage. |
| Moisture content | 0.5–3% w/w | Higher values may reduce stability; target set per product. |
| Moisture method | Karl Fischer titration | Coulometric for low levels; volumetric for higher levels. |
| Cake appearance | Uniform, intact, no collapse | Visual inspection is qualitative and not a potency measure. |
| Reconstitution time | Seconds to several minutes | Depends on cake density, excipients, and diluent. |
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.
A formulation often contains excipients that protect the active ingredient during freezing and drying. Bulking agents provide structure, while lyoprotectants stabilize sensitive molecules. The freezing step can produce ice crystals whose size and distribution affect the drying rate, and cycle design includes freezing, annealing, and drying phases. If the product temperature rises above a critical value, the cake may collapse or lose its porous structure. Successful lyophilization therefore depends on the interaction between formulation, equipment, and cycle design.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen to convert liquid water into ice. Next, the pressure is reduced below the triple point of water so that ice changes directly into vapor without passing through a liquid phase. This step is called primary drying. The result is a porous solid or cake that retains the original shape of the frozen solution.
After primary drying, secondary drying removes water that remains bound to the material. This stage raises the shelf temperature while maintaining low pressure, which encourages desorption of unfrozen water. Residual moisture can be reduced to a low percentage, improving stability for many products. The process parameters, including freezing rate, shelf temperature, and chamber pressure, influence the final pore structure and reconstitution behavior. Control of these variables helps prevent collapse or meltback during drying.
== Transition from plaque induced gingivitis to periodontitis == Plaque-induced gingivitis and the more severe stage plaque induced periodontitis are the most common of the periodontal diseases. While in some individuals gingivitis never progresses to periodontitis, periodontitis is always preceded by gingivitis. In 1976, Page & Schroeder introduced an innovative new analysis of periodontal disease based on histopathologic and ultrastructural features of the diseased gingival tissue. Although this new classification does not correlate with clinical signs and symptoms and is admittedly "somewhat arbitrary," it permits a focus of attention pathologic aspects of the disease that were, until recently, not well understood. This new classification divided plaque-induced periodontal lesions into four stages, namely, initial lesion, early lesion, established lesion and advanced lesion.
=== Supplements === The use of certain amino acids may slow muscle breakdown by providing the body with the building blocks needed for metabolism of muscle and glucose. Specifically, leucine and valine may block muscle breakdown. Glutamine is used in oral supplements for people with advanced cancer or HIV/AIDS. β-hydroxy β-methylbutyrate (HMB) is a molecule that comes from leucine that promotes muscle growth. Studies show positive results for chronic pulmonary disease, hip fracture, and in AIDS-related and cancer-related cachexia. However, it is often studied along with other nutrients, making it difficult to assess its effects alone. Creatine supplementation may help reduce muscle wasting, though more research is needed.
== Role in diet == Scientists at the University of Manchester have discovered that hemopressin could be used as an appetite suppressant without having the side effects of many other drugs that are used for this purpose. In laboratory tests hemopressin was administrated to mice and rats, which significantly reduced food intake. Hemopressin works by affecting the reward centres of the brain which make us feel happy when we eat too much. A further research should be carried out in order to confirm these effects and the safety on people.
== Pathology == Synovium can become irritated and thickened (synovitis) in conditions such as osteoarthritis, Ross River virus or rheumatoid arthritis (RA). The fibroblast-like synoviocytes (FLS) play a key role in the pathogenesis of RA, and the aggressive phenotype of FLS in RA and the effect these cells have on the microenvironment in the joint can be summarized into hallmarks that distinguish them from healthy FLS. These hallmark features of FLS in RA are divided into seven cell-intrinsic hallmarks (such as reduced apoptosis and impaired contact inhibition) and four cell-extrinsic hallmarks (such as their ability to recruit and stimulate immune cells). In general, inflamed synovium is accompanied by extra macrophage recruitment (as well as the existing type A cells), fibroblast proliferation and an influx of inflammatory cells including lymphocytes, monocytes and plasma cells. When this happens, the synovium can interfere with the normal functioning of the joint. Excessive thickened synovium, filled with cells and fibrotic collagenous tissue, can physically restrict joint movement. The synovial fibroblasts may make smaller hyaluronan so it is a less effective lubricant of the cartilage surfaces. Under stimulation from invading inflammatory cells, the synovial cells may also produce enzymes (proteinases) that can digest the cartilage extracellular matrix. Fragments of extracellular matrix can then further irritate the synovium.
== Human genes == Human genes encoding enzymes with procollagen galactosyltransferase activity include: Human genes encoding enzymes with procollagen galactosyltransferase activity (EC 2.4.1.50) include:
Sources: en.wikipedia.org
=== Biosynthesis === Caryophyllene is a common sesquiterpene among plant species. It is biosynthesized from the common terpene precursors dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP). First, single units of DMAPP and IPP are reacted via an SN1-type reaction with the loss of pyrophosphate, catalyzed by the enzyme GPPS2, to form geranyl pyrophosphate (GPP). This further reacts with a second unit of IPP, also via an SN1-type reaction catalyzed by the enzyme IspA, to form farnesyl pyrophosphate (FPP). Finally, FPP undergoes QHS1 enzyme-catalyzed intramolecular cyclization to form caryophyllene.
=== Ebola === After initial studies by the Centers for Disease Control and Prevention (CDC, Atlanta, Georgia, US) in cell culture models, on 6 October 2014, Chimerix received an FDA authorization for emergency investigational new drug applications of brincidofovir for the treatment of Ebola virus disease. Brincidofovir was administered to the first patient diagnosed in the Ebola virus disease outbreak in the US in 2014. The patient was given the drug starting six days after hospital admission when he was already critically ill; he died four days later. Brincidofovir was also given to Ebola patient Ashoka Mukpo at the Nebraska Medical Center, who had developed the disease and then was pronounced Ebola-free and released from the center on 22 October 2014. In October 2014, Chimerix reported it had been given approval by the FDA to start Phase 2 trials in patients infected with ebolaviruses for brincidofovir's safety, tolerability, and efficacy. Organised by a team of scientists at the University of Oxford, including Peter Horby, Jake Dunning, Laura Merson and Trudie Lang, a trial commenced during January 2015 in Liberia, but was subsequently discontinued. Because of a lack of suitable subjects in Liberia, Oxford University and Médecins Sans Frontières planned to extend the trial to Sierra Leone, where there were still Ebola cases; but on 30 January 2015, the manufacturer decided to withdraw support for the trial and end discussion of future trials.
DROME: Gln-Tyr-Met-Ser-Pro-Cys-His-Phe-Lys-Ile-Cys-Asn-Met-amide APIME: Thr-Met-Ile-Ser-Tyr-Met-Thr-Leu-Cys-His-Phe-Lys-Ile-Cys-Asn-Met-amide DAPPU: Asp-Ser-Tyr-Leu-Ser-Met-Cys-His-Phe-Lys-Leu-Cys-Asn-Leu-amide
==== Film works and graphic novel ==== Antonov worked on the 2006 film Renaissance directed by Christian Volkman. He then wrote and illustrated the graphic novel The Colony: A Structure Celebrating the Triumphs of Technology, published in 2010. Antonov was also a co-writer and production designer of the 2011 French sci-fi film The Prodigies.
=== Microdase === Microdase is a modified oxidase test used to differentiate Micrococcus from Staphylococcus by testing for the presence of cytochrome c. A positive result produces a dark color around the inoculant while negative result produces no color change.
Sources: en.wikipedia.org
The second stage of socialist government of the reign of Juan Carlos I lasted two legislative periods, which were very different. The first (2004–2008) were "years of changes" and the second (2008–2011) "years of crisis."
=== Breast cancer === Pregnancy has a positive effect on the prognosis of breast cancer according to several studies and it apparently increases the chance of survival after diagnosis of breast cancer. Possible positive effects of pregnancy could be explained by the persistence of fetal cells in the blood and maternal tissues. Fetal cells are probably actively migrating from peripheral blood into the tumor tissue where they are preferentially settled in the tumor stroma and one their concentration decreases as they get closer to the healthy breast tissue. There are two suggested mechanisms by which the fetal cells could have the positive effect on the breast cancer prognosis. The first mechanism suggests that fetal cells only oversee cancer cells and they attract components of the immune system if needed. The second option is that the down-regulation of the immune system induced by the presence of fetal cells could ultimately lead to cancer prevention, because women in whom FMC is present produce lower concentrations of inflammatory mediators, which may lead to the development of neoplastic tissue. The effect also depends on the level of microchimerism: Hyperchimerism (a high rate of microchimerism) and hypochimerism (a low rate of microchimerism) can be related to the negative effect of FMC and thus can promote a worse prognosis of breast cancer. Apparently, women with breast cancer may fail in the process of obtaining and maintaining allogeneic fetal cells.
Compared to amorphous structures, semi-crystalline structures lead to a higher stiffness, density, melting temperature and higher resistance of a polymer. Cross-linked polymers: Wide-meshed cross-linked polymers are elastomers and cannot be molten (unlike thermoplastics); heating cross-linked polymers only leads to decomposition. Thermoplastic elastomers, on the other hand, are reversibly "physically crosslinked" and can be molten. Block copolymers in which a hard segment of the polymer has a tendency to crystallize and a soft segment has an amorphous structure are one type of thermoplastic elastomers: the hard segments ensure wide-meshed, physical crosslinking.
The yeast genus Saccharomyces (sugar mold) is favored for winemaking (for both grapes as well as other fruit wines in addition to being used in brewing and breadmaking) because of the generally reliable and positive attributes it can bring to the wine. These yeasts will usually readily ferment glucose, sucrose and raffinose and metabolize glucose, sucrose, raffinose, maltose and ethanol. However, Saccharomyces cannot ferment or utilize pentoses (such as arabinose) which is usually present in small amount in wines as residual sugars. In addition to Saccharomyces cerevisiae, other species within the genus Saccharomyces that are involved with winemaking include:
=== Agriculture === Natural freshwater diatomaceous earth is used in agriculture for grain storage as an anticaking agent, as well as an insecticide. It is approved by the U.S. Food and Drug Administration as a feed additive to prevent caking. Some believe it may be used as a natural anthelmintic (dewormer), although studies have not shown it to be effective. Some farmers add it to their livestock and poultry feed to prevent the caking of feed. "Food-Grade Diatomaceous Earth" is widely available in agricultural feed supply stores. Freshwater diatomite can be used as a growing medium in hydroponic gardens. It is also used as a growing medium in potted plants, particularly as bonsai soil. Bonsai enthusiasts use it as a soil additive, or pot a bonsai tree in 100% diatomaceous earth. In vegetable gardening it is sometimes used as a soil conditioner, because like perlite, vermiculite, and expanded clay, it retains water and nutrients, while draining fast and freely, allowing high oxygen circulation within the growing medium.
Sources: en.wikipedia.org
Most lyophilized products are stored in sealed containers at controlled temperature and humidity. Some require refrigeration, while others are stable at room temperature. Protection from light and moisture is often necessary.
Cake collapse indicates that the porous structure was lost during drying. It can result from excessive product temperature or an unsuitable formulation. Collapsed cakes may have slower reconstitution and are often rejected by visual inspection.
Residual moisture affects the chemical and physical stability of a lyophilized solid. High moisture can promote degradation, aggregation, or cake shrinkage. The acceptable range is set for each product based on stability data.
Lyophilization relies on sublimation, so water moves from solid ice to vapor without becoming liquid. The material is frozen, pressure is reduced, and controlled heat is supplied. Vapor is captured on a cold condenser, leaving a dry porous solid.