This is a working overview of glass transition, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white porous cake | Color depends on formulation. |
| Typical storage temperature | 2–8 °C | Refrigerated for many biologics. |
| Residual moisture | <1% to 3% | Low moisture improves stability. |
| Container | Sealed glass vial | Often with rubber stopper and aluminum crimp. |
| Reconstitution time | Seconds to minutes | Varies with cake density and diluent. |
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.
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.
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.
When the recombinant MBP includes a signal peptide, the fusion protein can be exported into the periplasmic space, which facilitates its purification since the periplasmic fluid contains only a limited number of proteins and can be recovered either by an osmotic shock or by permeabilization of the bacterial outer membrane with antibiotics such as Polymyxin B. Such an export of the fusion protein into the periplasmic space enables the formation of disulfide bonds in the passenger protein, for example antibody fragments. Foreign proteins that are exported or secreted in their native organism, can usually be exported into the E. coli periplasm by fusion with MBP. Examples of cytoplasmic proteins that could be exported by fusion with MBP, include the monomeric Klenow polymerase and the dimeric Gene V protein of phage M13. When the recombinant MBP includes either a defective or no signal peptide the fusion protein remains within the bacterial cytoplasm from where it can be recovered by breaking open the cells. The fusion of proteins with MBP usually enhances their solubility and facilitates their proper folding so that the fusion proteins are most often bifunctional. In addition, such fusions can facilitate the crystallisation of difficult proteins, e.g. membrane proteins. The crystallized protein can often have their structures solved by X-ray crystallography using molecular replacement on a known MBP structure.
The use of psilocybin mushrooms in religious ceremonies dating back thousands of years is contested. Despite popular narratives portraying psychedelics as ancient, widespread, and primarily used by shamans for therapeutic healing, anthropological and historical research shows their traditional use was limited, recent, and culturally specific, with modern Western interpretations largely shaped by idealization, tourism, and ideological agendas. Reliable evidence shows that psilocybin mushrooms were used ritualistically in pre-Columbian Mexico but were otherwise rare, with most claims of ancient widespread use exaggerated or misinterpreted. It has been argued that the Tassili Mushroom Figure, discovered in Tassili, Algeria, is evidence of an early psilocybin-containing mushroom cult. 6,000-year-old pictographs discovered near Villar del Humo, Spain, illustrate several mushrooms that have been argued to be Psilocybe hispanica, a hallucinogenic species native to the area. Some scholars have also interpreted archaeological artifacts from Mexico and the so-called Mayan "mushroom stones" of Guatemala as evidence of ritual and ceremonial use of psychoactive mushrooms in the Mayan and Aztec cultures. After Spanish conquistadors of the New World arrived in the 16th century, chroniclers reported mushroom use by the natives for ceremonial and religious purposes. According to the Dominican friar Diego Durán in The History of the Indies of New Spain (published c.
== Using genomics to infer early lines of evolution == Instead of relying on a single gene such as the small-subunit ribosomal RNA (SSU rRNA) gene to reconstruct early evolution, or a few genes, scientific effort has shifted to analyzing complete genome sequences. Evolutionary trees based only on SSU rRNA alone do not capture the events of early eukaryote evolution accurately, and the progenitors of the first nucleated cells are still uncertain. For instance, analysis of the complete genome of the eukaryote yeast shows that many of its genes are more closely related to bacterial genes than they are to archaea, and it is now clear that archaea were not the simple progenitors of the eukaryotes, in contradiction to earlier findings based on SSU rRNA and limited samples of other genes. One hypothesis is that the first nucleated cell arose from two distinctly different ancient prokaryotic (non-nucleated) species that had formed a symbiotic relationship with one another to carry out different aspects of metabolism. One partner of this symbiosis is proposed to be a bacterial cell, and the other an archaeal cell. It is postulated that this symbiotic partnership progressed via the cellular fusion of the partners to generate a chimeric or hybrid cell with a membrane bound internal structure that was the forerunner of the nucleus. The next stage in this scheme was transfer of both partner genomes into the nucleus and their fusion with one another. Several variations of this hypothesis for the origin of nucleated cells have been suggested.
== RSKSOP-175 analysis of petroleum gases == A widely used methods for headspace analysis is described by the United States Environmental Protection Agency (USEPA) was developed as a "high quality, defendable, and documented way to measure" methane, ethane, and ethene, RSKSOP-175 is a standard operating procedure (SOP) and an unofficial method employed by the USEPA to detect and quantify dissolved gases in water. This method has been used to quantify dissolved hydrogen, methane, ethylene, ethane, propane, butane, acetylene, nitrogen, nitrous oxide, and oxygen. The method uses headspace gas injected into a gas chromatographic column (GC) to determine the original concentration in a water sample.
As a result of these differences in molecular weights, EMP contains about 52%, EMP sodium about 48%, and EMP meglumine about 38% of the amount of estradiol within their structures as does an equal-mass quantity of estradiol.
Sources: en.wikipedia.org
The hats of the Australian Light Horse are decorated with emu feather plumes. Trademarks of early Australian companies using the emu included Webbenderfer Bros frame mouldings (1891), Mac Robertson Chocolate and Cocoa (1893), Dyason and Son Emu Brand Cordial Sauce (1894), James Allard Pottery Wares (1906), and rope manufacturers G. Kinnear and Sons Pty. Ltd. still use it on some of their products. There are around six hundred gazetted places in Australia with "emu" in their title, including mountains, lakes, hills, plains, creeks and waterholes. During the 19th and 20th centuries, many Australian companies and household products were named after the bird. In Western Australia, Emu beer has been produced since the early 20th century and the Swan Brewery continues to produce a range of beers branded as "Emu". The quarterly peer-reviewed journal of the Royal Australasian Ornithologists Union, also known as Birds Australia, is entitled Emu: Austral Ornithology. The comedian Rod Hull featured a wayward emu puppet in his act for many years and the bird returned to the small screen in the hands of his son Toby after the puppeteer's death in 1999. In 2019, American insurance company Liberty Mutual launched an advertising campaign that features LiMu Emu, a CGI-rendered emu. The animal sanctuary, Alveus Sanctuary, has an emu named Stompy. He was their first animal ambassador, after being hand raised by the Sanctuary's founder. He is known for "giving hugs" to guests at Alveus, including Ludwig, Jaiden Animations, Jack Manifold, Hasan Piker, and Valkryae.
=== Comparison with other medication === In 2018, heat-stable carbetocin, a formulation that does not require strict refrigeration, was found to be as good as oxytocin for reduction of postpartum hemorrhage after vaginal delivery. It is hoped that this will make oxytocic hemorrhage control more widely available and less expensive, which will be particularly useful in regions of developing countries where the cold chain (in drug transport and storage) is unreliable because of power outages or equipment problems. Due to carbetocin's considerably longer half-life, its effects are longer lasting than other oxytocin homologs such as oxytocin or barusiban. A single carbetocin dose compared to a placebo or an eight-hour intravenous drip of oxytocin in a randomized blind study, necessitated less additional oxytocin therapy following a Cesarean section. Oxytocin receptor antagonists, such as barusiban or atosiban have the opposite effect of depressing oxytocin receptor activity and can be used to stop premature labor and uterine contractions.
Organized crime groups also do a range of business and labor racketeering activities, such as skimming casinos, insider trading, setting up monopolies in industries such as garbage collecting, construction and cement pouring, bid rigging, getting "no-show" and "no-work" jobs, political corruption and bullying.
The radiological evaluation through HRCT is an essential point in the diagnostic pathway in IPF. HRCT is performed using a conventional computed axial tomographic scanner without injection of contrast agents. Evaluation slices are very thin, 1–2 mm (0.039–0.079 in). Typical HRCT of the chest of IPF demonstrates fibrotic changes in both lungs, with a predilection for the bases and the periphery. According to the joint ATS/ERS/JRS/ALAT 2011 guidelines, HRCT is an essential component of the diagnostic pathway in IPF which can identify UIP by the presence of:
== Structure == Optimer ligands are composed of single-stranded DNA or RNA polymers. These nucleic acid molecules can exhibit cognate base-pairing to produce sections of double-stranded DNA or RNA within the Optimer molecules. Optimer ligands form secondary and tertiary structures with compatible internal base-pairing at specific portions of the ligand where possible according to the specific sequence. As not all of the bases in the Optimer sequence will be compatible for internal double-stranded pairing, single-stranded loop and bulge regions will remain in the secondary and tertiary structures, where hydrogen bond acceptor and donor groups are exposed and available to interact with the selected target for target engagement and target binding. The Optimer library that is screened for specific binders consists of 1014 sequences that will form different variable sequence-dependent structures. The wide diversity in this library enables target binding to a range of different molecules. Optimer molecules can bind crevices and exposed epitopes on protein and cellular targets and can wrap around small molecule targets. This enables an increased target range compared to traditional antibody technology that has limitations in accurately binding small molecule targets. As Optimer technology stems from aptamers, Optimer ligands have the ability to operate as reversible structural switches, changing their structure when binding their target molecule.
Sources: en.wikipedia.org
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.
Moisture can cause the porous cake to collapse, increase molecular mobility, and accelerate chemical degradation. It may also promote microbial growth if the product lacks preservatives. Proper sealing and handling are essential to maintain stability.
Some formulations contain labile biological molecules that degrade even in the dry state at higher temperatures. Others have a low glass transition temperature, meaning the cake can soften or collapse at room temperature. Cold storage reduces molecular motion and slows degradation.
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.