If you have been reading about Sublimation and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-07-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
Quality control for lyophilized materials includes visual inspection of the cake, measurement of residual moisture, and tests for reconstitution time. An acceptable cake is typically uniform and may be slightly porous; shrinkage, meltback, or cracks can indicate process deviations. Analytical methods such as Karl Fischer titration, thermogravimetric analysis, and near-infrared spectroscopy quantify water content. Reconstitution time is recorded because a very slow or incomplete dissolution can signal collapse or aggregation. Stability studies compare samples stored under defined temperature and humidity conditions over months or years.
Regulatory expectations for lyophilized products focus on consistent manufacture and documented stability. Batches are often monitored for moisture, appearance, potency, and sterility where applicable. Process parameters such as shelf temperature, chamber pressure, and drying time are recorded and controlled within validated ranges. Open questions remain about how best to predict long-term stability from short accelerated studies, especially for complex biologics. Variations in freezing rate and ice crystal size can produce differences that are not always visible but may affect performance.
After drying, a lyophilized product is usually sealed under vacuum or an inert gas to limit moisture uptake. Residual water content is measured because small changes can alter chemical stability and cake appearance. Storage temperature depends on the material; many biological products are kept at 2–8 °C, while some require −20 °C or colder. Exposure to ambient humidity during handling can cause the porous solid to absorb water and collapse. Container closures and stoppers are therefore selected for low moisture transmission and compatibility.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
Freezing determines ice crystal structure and pore size, which affect drying speed and product uniformity. Rapid freezing creates small crystals, while slow freezing creates larger crystals and often faster sublimation. During primary drying, chamber pressure is held below the vapor pressure of ice, and shelf temperature supplies heat for sublimation. The ice front recedes, leaving a porous matrix. Thermal limits such as collapse and eutectic temperatures set safe boundaries for formulation. These limits vary with solute composition and concentration.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 2–8 °C | Common for biological materials; some require −20 °C or colder |
| Residual moisture specification | 0.5–3.0% w/w | Product-specific; measured after drying |
| Common moisture method | Karl Fischer titration | Coulometric or volumetric; detects water content |
| Cake appearance | Uniform and porous | Collapse, meltback, or cracks are deviations |
| Reconstitution time | Seconds to several minutes | Depends on formulation, cake structure, and diluent |
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.
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.
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.
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.
Quality control also examines cake structure, color, and reconstitution behavior. A collapsed or shrunken cake can indicate a thermal excursion during drying. Analytical methods such as X-ray diffraction, differential scanning calorimetry, and near-infrared spectroscopy can detect crystallinity or moisture distribution. Regulatory expectations focus on validated assays and lot-to-lot consistency. Questions remain about how well accelerated stability tests predict long-term behavior for every formulation. Visual inspection remains common but is subjective without trained reviewers and reference images.
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.
"Chains & Whips" contains a sample of "Take Five", composed by Paul Desmond, as performed by Cherry Wainer and Don Storer. "P.O.V." contains an interpolation of the Streets of San Francisco theme tune, composed by Patrick Williams. "So Be It" contains a sample of "Maza Akoolou", written by Fata El Shatea and Mohammed Abdel Wahab, and performed by Talal Maddah. "Inglorious Bastards" contains a sample of Jesse Jackson's opening speech to Wattstax. "Let God Sort Em Out / Chandeliers" contains a sample of the Sarge theme tune, composed by David Shire.
In an RTG, heat generation cannot be varied with demand or shut off when not needed and it is not possible to save more energy for later by reducing the power consumption. Therefore, auxiliary power supplies (such as rechargeable batteries) may be needed to meet peak demand, and adequate cooling must be provided at all times including the pre-launch and early flight phases of a space mission. While spectacular failures like a nuclear meltdown or explosion are impossible with an RTG, there is still a risk of radioactive contamination if the rocket explodes or the device reenters the atmosphere and disintegrates. For terrestrial RTGs, damage by storms, seasonal ice, or vandalism are potential risks.
== Biochemical structure == Kex2 was first purified and characterized by Charles Brenner and Robert Fuller in 1992. The Kex2 crystal structure was solved by a group led by Dagmar Ringe, Robert Fuller and Gregory Petsko. That of Furin was determined by a group led by Manual Than and Wolfram Bode. The key features of Kex2 and Furin are a subtilisin-related catalytic domain, a specificity pocket that requires the amino acid amino terminal to the scissile bond to be arginine for rapid acylation, and a P-domain carboxy-terminal to the subtilisin domain, which is required for biosynthesis.
Sources: en.wikipedia.org
Films generate income from several revenue streams, including theatrical exhibition, home video, television broadcast rights, and merchandising. However, theatrical box-office earnings are the primary metric for trade publications in assessing the success of a film, mostly because of the availability of the data compared to sales figures for home video and broadcast rights, but also because of historical practice. Included on the list are charts of the top box-office earners (ranked by both the nominal and real value of their revenue), a chart of high-grossing films by calendar year, a timeline showing the transition of the highest-grossing film record, and a chart of the highest-grossing film franchises and series. All charts are ranked by international theatrical box-office performance where possible, excluding income derived from home video, broadcasting rights, and merchandise. Traditionally, war films, musicals, and historical dramas have been the most popular genres, but franchise films have been among the best performers of the 21st century. There is strong interest in the superhero genre, with eleven films in the Marvel Cinematic Universe featuring among the nominal top-earners. The most successful superhero film, Avengers: Endgame, is also the second-highest-grossing film on the nominal earnings chart, and there are four films in total based on the Avengers comic books charting in the top twenty-five.
The thomson (symbol: Th) is a unit that has appeared infrequently in scientific literature relating to the field of mass spectrometry as a unit of mass-to-charge ratio. The unit was proposed by R. Graham Cooks and Alan L. Rockwood naming it in honour of J. J. Thomson, who measured the mass-to-charge ratio of electrons and ions.
were provided by Kröger and Schlickeiser, so that there is no need to perform a numerical integration to solve the SIR model (a simplified example practice on COVID-19 numerical simulation using Microsoft Excel can be found here ), to obtain its parameters from existing data, or to predict the future dynamics of an epidemics modeled by the SIR model. The approximant involves the Lambert W function which is part of all basic data visualization software such as Microsoft Excel, MATLAB, and Mathematica. While Kendall considered the so-called all-time SIR model where the initial conditions
24 May – Three crew members are injured in an engine room explosion aboard a ship berthed in Bluff. 26 May: Two of the New Zealand Government's "non-financial benefit sanctions" come into force: namely money management payment cards and community work experience activities. Heavy rain leads to flooding in Nelson and Westport. 27 May: Police Commissioner Richard Chambers overturns a directive from March 2025 instructing Police officers not to investigate "lower value" thefts, petrol drive-offs, shoplifting and fraud crimes. The Department of Conservation proposes axing 84 jobs to meet a Government directive for a 6.5 percent reduction in spending. 28 May: Health Minister Simeon Brown and Finance Minister Nicola Willis announce that the Government will invest in 126 additional beds and treatment spaces at Wellington Hospital. Anti-mining protesters picket ANZ Bank branches in Dunedin and other centres to protest against the bank's relationship with coal company Bathurst Resources, which has applied for a fast-track consent to mine the Denniston Plateau. 29 May: The Transport Accident Investigation Commission (TAIC) launches an explosion into a boiler room explosion aboard a ship berthed in Bluff that occurred on 24 May. A car crash causes a power outage and traffic disruption in Rotorua's Pukehangi suburb. 30 May: Police launch a review into how many cases of retail crime were filed after the rescindment of a controversial directive directing the Police not to investigate lower-value retail crimes.
Sources: en.wikipedia.org
== Career == In 1999, Sherrill joined the faculty of the school of chemistry and biochemistry at Georgia Tech. He joined the school of computational science and engineering as a joint faculty member in 2006. He became associate director of Georgia Tech's Institute for Data Engineering and Science (IDEaS) in 2017. He has been an associate editor of The Journal of Chemical Physics since 2009.
=== Noise reduction === Noise reduction can be accomplished either in computer hardware or software. Examples of hardware noise reduction are the use of shielded cable, analog filtering, and signal modulation. Examples of software noise reduction are digital filtering, ensemble average, boxcar average, and correlation methods.
They proposed a formation theory accounting for the dependence of microstructure on anodising conditions, and demonstrated the formation of porous gallium arsenide — the first porous III–V semiconductor — confirming the generality of the mechanism. In 1986, the same group also demonstrated that chemical stain etching produces porous silicon identical in structure to that formed by anodisation, unifying the two formation routes. This work on the formation mechanism and microstructure provided the basis for much of the subsequent research into the material's properties and applications—in fields as diverse as optoelectronics and photonics, chemical and biological sensing, biomedicine and drug delivery, photovoltaics, energy storage and microelectromechanical systems—and the model continues to be cited as a standard reference for porous silicon formation. Despite the discovery of porous silicon in the 1950s and the elucidation of its formation mechanism in the mid-1980s, the material attracted little wider attention until the end of the decade, when its nanoscale structure—a network of nanometre-sized pores within a crystalline silicon skeleton—was recognised as the source of optical, electronic and surface properties quite different from those of bulk silicon, triggering the rapid growth of interest that established porous silicon as a versatile nanostructured material with applications across optoelectronics, sensing, biomedicine, photovoltaics, energy storage and microelectronics.
Sources: en.wikipedia.org
Most are held in sealed containers at controlled temperatures, often 2–8 °C, while some require frozen storage. Protection from moisture and light helps preserve the dry matrix. Exact conditions are set by the manufacturer or study protocol.
Cake collapse suggests the material exceeded its collapse temperature during drying or later absorbed moisture. It can lead to slower reconstitution, uneven moisture, and reduced stability. Appearance alone may not reveal the cause, so process records and moisture tests are used together.
Some residual moisture is common and may be acceptable within a defined range. Very low moisture can alter stability or increase brittleness, while high moisture promotes hydrolysis and microbial risk. Specifications are based on product-specific stability data.
Conventional drying uses heat to evaporate liquid water, often at temperatures that can degrade sensitive materials. Lyophilization freezes the material first and then removes water by sublimation under vacuum. This avoids prolonged exposure to liquid water and high heat.