primary drying raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-07-16 and is reviewed periodically as new material appears.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
Lyophilization is a dehydration technique in which a product is frozen and the solvent is removed under reduced pressure. The low pressure allows ice to sublimate directly into vapor without passing through a bulk liquid phase. This differs from conventional drying, where heat drives evaporation and can damage heat-sensitive structures. The process is used for biological materials, pharmaceutical formulations, and some foods. Its main advantage is preservation of porous structure and rapid reconstitution.
Freezing is the first stage and sets the ice structure that later becomes the pore network. The formulation is cooled below its freezing point, often with a controlled ramp, and solutes concentrate as ice forms. Primary drying then lowers chamber pressure and supplies heat to sublime the ice. The product temperature must stay below its collapse or eutectic temperature to prevent structural loss. Secondary drying raises the temperature modestly to remove bound water and achieve a low residual moisture.
A freeze-dryer consists of a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. Vials, ampoules, or bulk trays hold the product during the cycle. The condenser traps water vapor as ice at a temperature lower than the product. Cycle development balances shelf temperature, chamber pressure, and time. Scale-up can be difficult because heat and mass transfer change with equipment size, so process analytical tools and conservative validation are often used.
| Property | Value | Notes |
|---|---|---|
| Common name | Freeze-drying | Process removes water by sublimation under vacuum. |
| Typical primary drying shelf temperature | -40 C to -10 C | Set below the formulation's collapse temperature. |
| Typical chamber pressure | 0.05-0.3 mbar | Low pressure allows ice to sublime below its triple point. |
| Water content after drying | 0.5-3% by weight | Higher values may reduce storage stability for some materials. |
| Key thermal parameter | Collapse temperature | Measured by freeze-drying microscopy or differential scanning calorimetry. |
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
Adults typically range from 120 to 188 cm (47 to 74 in) in head-and-body length, and 63 to 103.5 cm (24.8 to 40.7 in) in shoulder height. Although the American black bear is the smallest bear species in North America (smaller than the brown and polar bears), large males exceed the size of other bear species in other continents. Weight tends to vary according to age, sex, health and season. Adult males typically weigh between 60–300 kg (130–660 lb) with females averaging between 33% and 50% less at 40–150 kg (88–331 lb). Seasonal variation in weight is very pronounced: in autumn, their pre-den weight tends to be 30% higher than in spring, when black bears emerge from their dens. Bears on the East Coast tend to be heavier on average than their West Coast counterparts, although they typically follow Bergmann's rule regarding average size being inversely correlated with environment temperature, and bears from the northwest are often slightly heavier than the bears from the southeast. In California, studies indicate that the average adult mass is 86 kg (190 lb) in males and 58 kg (128 lb) in females. Adults in Yukon Flats National Wildlife Refuge in east-central Alaska were found to average 87.3 kg (192 lb) in males and 63.4 kg (140 lb) in females, whereas on Kuiu Island in southeastern Alaska (where nutrient dense salmon are readily available) adults averaged 115 kg (254 lb). In Great Smoky Mountains National Park, adult males averaged 112 kg (247 lb) and adult females averaged 47 kg (104 lb) per one study.
Protein L was first isolated from the surface of bacterial species Peptostreptococcus magnus and was found to bind immunoglobulins through L chain interaction, from which the name was suggested. It consists of 719 amino acid residues. The molecular weight of protein L purified from the cell walls of Peptostreptoccus magnus was first estimated as 95kD by SDS-PAGE in the presence of reducing agent 2-mercaptoethanol, while the molecular weight was determined to 76kD by gel chromatography in the presence of 6 M guanidine HCl. Protein L does not contain any interchain disulfide loops, nor does it consist of disulfide-linked subunits. It is an acidic molecule with a pI of 4.0. Unlike protein A and protein G, which bind to the Fc region of immunoglobulins (antibodies), protein L binds antibodies through light chain interactions. Since no part of the heavy chain is involved in the binding interaction, Protein L binds a wider range of antibody classes than protein A or G. Protein L binds to representatives of all antibody classes, including IgG, IgM, IgA, IgE and IgD. Single chain variable fragments (scFv) and Fab fragments also bind to protein L. Despite this wide binding range, protein L is not a universal antibody-binding protein. Protein L binding is restricted to those antibodies that contain kappa light chains. In humans and mice, most antibody molecules contain kappa (κ) light chains and the remainder have lambda (λ) light chains. Protein L is only effective in binding certain subtypes of kappa light chains.
== NAAS selected bibliography == 1955 Nuclear magnetic resonance saturation and rotary saturation in solids. Physical Review 98(6):1787–1809. 1959 With A. G. Anderson. Nuclear spin-lattice relaxation in metals. Physical Review 116(3):583–591. 1963. Pure nuclear electric quadrupole resonance in impure copper. Physical Review 130(2):589–595. 1963 With M. Eisenstadt. Nuclear spin relaxation by translational diffusion in solids. Physical Review 132(2):635–643. Pure nuclear electric quadrupole resonance in impure copper. Physical Review 130(2):589–595. 1965 The theory of relaxation processes. In Advances in Magnetic and Optical Resonance, pp. 1–32. 1967 Local-field mapping in mixed-state superconducting vanadium by nuclear magnetic resonance. Physical Review 162(2):367–374. 1969 Nuclear spin thermodynamics in the rotating frame. Science 164(3883):1015–1023. 1970 With R. K. Gupta. Double nuclear magnetic resonance observation of electron exchange between ferri- and ferrocytochrome c. Science 169(3951):1204–1206. 1971 With H. E. Bleich. Higher resolution NMR of rare spins in solids [1]. The Journal of Chemical Physics 55(11):5405–5406. 1971 With R. K. Gupta. Pulsed Fourier transform nuclear magnetic resonance spectrometer. In Advances in Magnetic and Optical Resonance, pp. 81–115. 1973 With A. Z. Genack. Nuclear spin diffusion and its thermodynamic quenching in the field gradients of a Type-II superconductor. Physical Review Letters 31(19):1204–1207. 1975 With S. D. Kunz and E. K. Ralph. Dynamic range in Fourier transform proton magnetic resonance.
Sources: en.wikipedia.org
Topilutamide, known more commonly as fluridil and sold under the brand name Eucapil, is an antiandrogen medication which is used in the treatment of pattern hair loss in men and women. It is used as a topical medication and is applied to the scalp. Topilutamide belongs to a class of molecules known as perfluoroacylamido-arylpropanamides. Topilutamide is a nonsteroidal antiandrogen (NSAA), or an antagonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). Topilutamide was introduced for medical use in 2003. It is marketed only in the Czech Republic and Slovakia. The patent for Topilutamide expired in 2020.
An electrical repeater, or synchro, was added to the gonio dial. To measure the range, a new dial was added that moved a mechanical marker to a selected blip on the display. When a particular target was properly selected, the operator pushed a button to activate the fruit machine, which then read these inputs. In addition to the inputs, the fruit machine also had a series of local corrections for both angle and altitude, as measured by calibration flights and stored in the machine in telephone uniselectors. These corrections were automatically added to the calculation, eliminating the time-consuming lookup of these numbers from tables. The output was the altitude, which then allowed the plotters to determine the proper over-ground distance to the target. Later versions of the fruit machine were upgraded to directly output the position of the aircraft with no manual operation. Using the same buttons to send settings to the machine, the operator simply triggered the system and the outputs were used to drive a T-square-like indicator on the chart, allowing the operator to read the calculated location directly. This reduced the number of people needed at the station and allowed the station to be reorganized into a much more compact form. No longer did the operator call readings out to the plotters; now they sat directly beside the plotting table so they could see if the results looked right, while the tellers could see the plot and call it into the area plotting room.
== Honors and awards == Dyson was elected a Fellow of the Royal Society (FRS) in 1952. Dyson was elected to the American Academy of Arts and Sciences in 1958. Dyson was elected to the United States National Academy of Sciences in 1964. Dyson was awarded the Dannie Heineman Prize for Mathematical Physics in 1965, Lorentz Medal in 1966, Max Planck Medal in 1969, the J. Robert Oppenheimer Memorial Prize in 1970, the Harvey Prize in 1977 and Wolf Prize in 1981. Dyson was elected to the American Philosophical Society in 1976. In 1986, Dyson received the Golden Plate Award of the American Academy of Achievement. In 1989, Dyson was elected as an Honorary Fellow of Trinity College, University of Cambridge. In 1990, Dyson taught at Duke University as a Fritz London Memorial Lecturer. Dyson published a number of collections of speculations and observations about technology, science, and the future. In 1996, he was awarded the Lewis Thomas Prize for Writing about Science. In 1993, Dyson was given the Enrico Fermi Award. In 1995, he gave the Jerusalem-Harvard Lectures at the Hebrew University of Jerusalem, sponsored jointly by the Hebrew University and Harvard University Press that grew into the book Imagined Worlds. In 2000, Dyson was awarded the Templeton Prize for Progress in Religion. In 2003, Dyson was awarded the Telluride Tech Festival Award of Technology in Telluride, Colorado. In 2011, Dyson received as one of twenty distinguished Old Wykehamists at the Ad Portas celebration, the highest honor that Winchester College bestows. In 2011, Dyson received the Arthur C.
Sources: en.wikipedia.org
=== Cage-free eggs === In 2022, Outback Steakhouse's parent company, Bloomin' Brands, announced their commitment to source 100% cage-free eggs across all of their locations by 2030. In 2024, they reported that they had reached this goal in their United States locations.
=== Mikel Brady === Mikel Edward Brady II (born March 11, 1989), the ringleader of the prison escape and murders, originally came from Randolph, Vermont, where he was born and raised. Brady reportedly had an unhappy childhood marred by abuse. He was born to a teenage mother and raised by a physically abusive father. From an early age, Brady suffered from developmental issues and was later diagnosed with bipolar disorder and post-traumatic stress disorder (PTSD). Despite these diagnoses, Brady's father was reportedly against him taking prescribed medications, preventing him from receiving proper treatment during his formative years. Brady's descent into criminal behavior began during his teenage years. He became involved in a drug and burglary ring responsible for numerous break-ins in the Randolph area. In 2008, he was arrested for stealing 209 sticks of dynamite from a quarry in Bethel, Vermont. The following year, in 2009, he was charged in connection with a violent home invasion in South Royalton that left the victim with a severe brain injury. Attempting to evade the law, Brady fled to Mexico, but he was eventually captured, extradited, and imprisoned in Vermont. After serving the minimum sentence and demonstrating good behavior behind bars, Brady was released in 2012. For a brief period, it seemed as though he was turning his life around. He found employment at a butcher shop in Randolph, joined a local softball league, and began taking his medications consistently. During this time, his girlfriend became pregnant, and the couple welcomed a son.
== Causes == It is mainly unknown what causes sJIA. There have been reports of seasonal fluctuations in the incidence of sJIA in some places but not in others. Although it has frequently been claimed that infectious organisms cause the condition to manifest, microbiologic and virologic analyses are unable to pinpoint a single agent as the cause. Since a negative septic screen is required for the diagnosis, sJIA is not an infectious disease by definition. There is evidence that suggests a genetic predisposition plays a role in the etiology of sJIA.
Sources: en.wikipedia.org
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.
Freezing determines ice crystal size, pore structure, and the concentration of solutes in remaining liquid. Faster freezing generally creates smaller ice crystals and a denser dried matrix. These features affect drying rate and reconstitution behavior.
Lyophilization reduces water content but usually leaves a small amount of water in the dried material. Some water remains bound to solids or trapped in the dried matrix. Very low water targets can require extended secondary drying, which may alter product stability.
Yes, the terms are generally interchangeable. Lyophilization is more common in pharmaceutical and laboratory contexts, while freeze-drying appears widely in food science and general writing. Both describe removal of solvent by sublimation under vacuum after freezing.