Sublimation 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 2025-08-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Misconceptions about lyophilization include the idea that dried products are indefinitely stable or that vacuum sealing eliminates all degradation. Chemical reactions can continue in the solid state, and some proteins lose activity even at low moisture. Another misconception is that any freeze-dryer cycle can be scaled by time alone; heat and mass transfer differ with equipment and load. Open questions remain about predicting long-term stability from short accelerated studies, particularly for amorphous formulations. Real-time stability data remain the standard for shelf-life assignment.
After lyophilization, the dried product is often sealed under vacuum or an inert gas to limit moisture and oxygen exposure. Vials, stoppers, and seals must maintain their barrier throughout shelf life. Storage temperature depends on product sensitivity: some cakes tolerate controlled room temperature, while labile biologics require refrigeration. Humidity is a critical variable because dried cakes are hygroscopic and can absorb water when exposed to air. Handling procedures therefore limit open-vial time and use desiccated environments for sampling.
| 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. |
The process relies on the phase diagram of water, where the triple point marks the conditions at which ice, liquid water, and vapor coexist. By maintaining pressure below this point, typically around 0.01 to 0.1 millibar, sublimation becomes the dominant mechanism. Formulations often include excipients such as sugars or polymers that act as lyoprotectants and bulking agents. These additives help preserve the structure of the active ingredient and prevent collapse during drying. The choice of excipient and freezing rate influences the final cake morphology and stability.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
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.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
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 technique of knocking down genes using RNAi therapeutics has demonstrated success in randomized controlled clinical studies. These medications are a growing class of siRNA-based drugs that decrease the expression of proteins encoded by certain genes. To date, five RNAi medications have been approved by regulatory authorities in the US and Europe: patisiran (2018), givosiran (2019), lumasiran (2020), inclisiran (2020 in Europe with anticipated US approval in 2021), and vutrisiran (2022). While all of the current regulatory body approved RNAi therapeutics focus on diseases that originate in the liver, additional medications under investigation target a host of disease areas including cardiovascular diseases, bleeding disorders, alcohol use disorders, cystic fibrosis, gout, carcinoma, and eye disorders. Patisiran is the first double stranded siRNA-based medication approved in 2018 and developed by Alnylam Pharmaceuticals. Patisiran uses the RNAi cascade to suppress the gene that codes for TTR (transthryetin). Mutations in this gene may cause the misfolding of a protein responsible for hereditary ATTR amyloidosis. To achieve therapeutic response, patisiran is encased by a lipid nanoparticle membrane that facilitates crossover into the cytoplasm. Once inside the cell, the siRNA begins processing by the enzyme Dicer. Patisiran is administered by a healthcare professional through an intravenous infusion with dosing based on body weight. Warnings and precautions include risk of infusion-related reactions and reduced vitamin A levels (serum).
== Reactivity == The presence of an aromatic ring, a ketone and a γ-lactam moiety, gives to isatin the rare potential to be used as both an electrophile and a nucleophile: indeed, it undergoes an enormous number of reactions, such as N-substitutions, electrophilic aromatic substitution at positions C-5 and C-7 of the phenyl ring, nucleophilic additions onto the C-3 carbonyl group, chemoselective reductions, oxidations, ring-expansions and spiro-annulations. Because of this unique reactivity, isatin is considered one of the most valuable building blocks in organic synthesis.
==== Backup site ==== A backup site or disaster recovery center is used to store data that can enable computer systems and networks to be restored and properly configured in the event of a disaster. Some organisations have their own data recovery centres, while others contract this out to a third-party. Due to high costs, backing up is rarely considered the preferred method of moving data to a DR site. A more typical way would be remote disk mirroring, which keeps the DR data as up to date as possible.
== Biochemistry == The stereoisomer (S)-1-pyrroline-5-carboxylate (also referred to as L-P5C) is an intermediate metabolite in the biosynthesis and degradation of proline and arginine. In prokaryotic proline biosynthesis, GSA is synthesized from γ-glutamyl phosphate by the enzyme γ-glutamyl phosphate reductase.
EF-Tu is a monomeric protein with molecular weight around 43 kDa in Escherichia coli. The protein consists of three structural domains: a GTP-binding domain and two oligonucleotide-binding domains, often referred to as domain 2 and domain 3. The N-terminal domain I of EF-Tu is the GTP-binding domain. It consists of a six beta-strand core flanked by six alpha-helices. Domains II and III of EF-Tu, the oligonucleotide-binding domains, both adopt beta-barrel structures. The GTP-binding domain I undergoes a dramatic conformational change upon GTP hydrolysis to GDP, allowing EF-Tu to dissociate from aa-tRNA and leave the ribosome. Reactivation of EF-Tu is achieved by GTP binding in the cytoplasm, which leads to a significant conformational change that reactivates the tRNA-binding site of EF-Tu. In particular, GTP binding to EF-Tu results in a ~90° rotation of domain I relative to domains II and III, exposing the residues of the tRNA-binding active site. Domain 2 adopts a beta-barrel structure, and is involved in binding to charged tRNA. This domain is structurally related to the C-terminal domain of EF2, to which it displays weak sequence similarity. This domain is also found in other proteins such as translation initiation factor IF-2 and tetracycline-resistance proteins. Domain 3 represents the C-terminal domain, which adopts a beta-barrel structure, and is involved in binding to both charged tRNA and to EF1B (or EF-Ts).
Sources: en.wikipedia.org
At the start of 2014, the company out-licensed its Friedreich's ataxia program, including a library of histone deacetylase inhibitor compounds, to BioMarin Pharmaceutical for US$2,000,000 and future milestone and royalty payments. Repligen has made several acquisitions through the early 2020s, including BioFlex Solutions and Tantti Laboratory Inc. among others. As of 2024, the company's President and Chief Executive Officer is Olivier Loeillot. As of 2025 it employs approximately 2,000 employees across several sites in the United States, Europe, and Asia.
== Environmental risk factors == Exposures to pesticides, metals, solvents (trichloroethylene), other toxicants (carbon disulfide), and air pollution are known factors in the development of Parkinson's disease. The World Health Organization (WHO) recommends reducing exposure to environmental factors associated with PD, including pesticides, trichloroethylene (TCE), and air pollution. Pesticides, TCE and some air pollutants appear to trigger PD pathology through their effects on key mechanisms involved in mitochondrial dysfunction, oxidative stress, and neuroinflammation. The cumulative effects of many different environmental exposures over a lifetime (the exposome) interact with underlying genetic factors to influence the development and progression of neurodegenerative diseases. The brain is particularly vulnerable to compounds that are able to cross the blood-brain barrier. Body-first and brain-first models of Parkinson's disease indicate possible connections between known environmental risk factors and PD mechanisms. Toxicants such as pesticides, industrial chemicals, and air pollution are usually inhaled, ingested, or both. In the nasal cavity and gut, they engage directly with mucosal surfaces where inflammation can occur. Pathways which can carry inflammation and toxins from the olfactory system and gut to the brain are well established. Key mechanisms are increasingly understood.
=== Sexual dysfunction === There is no evidence that yohimbe herbal supplements are effective as an aphrodisiac or as an OTC replacement for sildenafil (Viagra) for erectile dysfunction. Prescriptions for it are rare, and most United States pharmaceutical manufacturers have discontinued production of prescription capsules and tablets. In Canada during 2019, yohimbe products were removed from the market out of concern their use for sexual enhancement, weight loss, or as an exercise aid would pose serious health risks. It has been studied as a potential treatment for erectile dysfunction, but there is insufficient evidence to rate its effectiveness. Nevertheless, the quantity of yohimbine in dietary supplements, often advertised as promoting sexual function, has been found to overlap with prescription doses of yohimbine. In the United Kingdom, supplement preparations of yohimbe are banned as introducing a considerable risk for adverse effects. The drug form of yohimbine, called Yohimbine hydrochloride (yohimbine HCl) – which is not licensed as a medicine for any condition – may rarely and specifically be compounded by a pharmacist ("chemist" in the UK) as a prescription-only medicine for treating delayed ejaculation – a formulation that cannot be sold, supplied or advertised as a retail product. Yohimbine has been used to treat female sexual dysfunction, but there are few reported clinical trials and these do not show it to be better than placebo.
=== Treatment === To treat the food, it is exposed to a radioactive source for a set period of time to achieve a desired dose. Radiation may be emitted by a radioactive substance, or by X-ray and electron beam accelerators. Special precautions are taken to ensure the food stuffs never come in contact with the radioactive substances and that the personnel and the environment are protected from radiation exposure. Irradiation treatments are typically classified by dose (high, medium, and low), but are sometimes classified by the effects of the treatment (radappertisation, radicidation and radurisation). Food irradiation is sometimes referred to as "cold pasteurisation" or "electronic pasteurisation" because ionising the food does not heat it to high temperatures during the process, and the effect is similar to pasteurisation. The term "cold pasteurisation" is controversial because the term may be used to disguise the fact that the food has been irradiated, and pasteurisation and irradiation are fundamentally different processes.
Sources: en.wikipedia.org
== Neutrophil antigens == There are five (HNA 1–5) sets of neutrophil antigens recognized. The three HNA-1 antigens (a-c) are located on the low affinity Fc-γ receptor IIIb (FCGR3B :CD16b) The single known HNA-2a antigen is located on CD177. The HNA-3 antigen system has two antigens (3a and 3b) which are located on the seventh exon of the CLT2 gene (SLC44A2). The HNA-4 and HNA-5 antigen systems each have two known antigens (a and b) and are located in the β2 integrin. HNA-4 is located on the αM chain (CD11b) and HNA-5 is located on the αL integrin unit (CD11a).
In human anatomy, the penis (; pl.: penises or penes; from the Latin pēnis, initially 'tail') is an external sex organ (intromittent organ) through which males ejaculate and urinate. Together with the testes and surrounding structures, the penis functions as part of the male reproductive system. The main parts of the penis are the root, body, the epithelium, including the shaft skin, and the foreskin covering the glans. The body of the penis is made up of three columns of tissue: two corpora cavernosa on the dorsal side and corpus spongiosum between them on the ventral side. The urethra passes through the prostate gland, where it is joined by the ejaculatory ducts, and then passes through the corpus spongiosum. The external opening of the urethra at the tip of the glans is the urinary meatus. An erection is the stiffening expansion and orthogonal reorientation of the penis, which occurs during sexual arousal. Erections can occur in non-sexual situations; spontaneous non-sexual erections frequently occur during adolescence and sleep. In its flaccid state, the penis is smaller, gives to pressure, and the glans is covered by the foreskin. In its fully erect state, the shaft becomes rigid and the glans becomes engorged but not rigid. An erect penis may be straight or curved and may point at an upward angle, a downward angle, or straight ahead. As of 2015, the average erect human penis is 13.12 cm (5.17 in) long and has a circumference of 11.66 cm (4.59 in). Neither age nor size of the flaccid penis accurately predicts erectile length.
With that the majority of the regions left of the Upper Weser became North Rhine-Westphalian. In the end, at the meeting of the Zone Advisory Board on 20 September 1946, Kopf's proposal with regard to the division of the British occupation zone into three large states proved to be capable of gaining a majority. Because this division of their occupation zone into relatively large states also met the interests of the British, on 8 November 1946 Regulation No. 55 of the British military government was issued, by which the State of Lower Saxony with its capital Hanover were founded, backdated to 1 November 1946. The state was formed by a merger of the Free States of Brunswick, of Oldenburg and of Schaumburg-Lippe with the previously formed State of Hanover. But there were exceptions:
Radium was discovered by Marie Skłodowska-Curie and her husband Pierre Curie on 21 December 1898 in a uraninite (pitchblende) sample from Jáchymov. While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive. In July 1898, while studying pitchblende, they isolated an element similar to bismuth which turned out to be polonium. They then isolated a radioactive mixture consisting of two components: compounds of barium, which gave a brilliant green flame color, and unknown radioactive compounds which gave carmine spectral lines that had never been documented before. The Curies found the radioactive compounds to be very similar to the barium compounds, except they were less soluble. This discovery made it possible for the Curies to isolate the radioactive compounds and discover a new element in them. The Curies announced their discovery to the French Academy of Sciences on 26 December 1898. The naming of radium dates to about 1899, from the French word radium, formed in Modern Latin from radius (ray): this was in recognition of radium's emission of energy in the form of rays. The gaseous emissions of radium, radon, were recognized and studied extensively by Friedrich Ernst Dorn in the early 1900s, though at the time they were characterized as "radium emanations". In September 1910, Marie Curie and André-Louis Debierne announced that they had isolated radium as a pure metal through the electrolysis of pure radium chloride (RaCl2) solution using a mercury cathode, producing radium–mercury amalgam.
=== Recreational use === Zopiclone has the potential for non-medical use, dosage escalation, and drug dependence. It is taken orally and sometimes intravenously when used non-medically, and often combined with alcohol to achieve euphoria. Patients abusing the drug are also at risk of dependence. Withdrawal symptoms can be seen after long-term use of normal doses even after a gradual reduction regimen. The Compendium of Pharmaceuticals and Specialties recommends zopiclone prescriptions not exceed 7 to 10 days, owing to concerns of addiction, tolerance, and physical dependence. Two types of drug misuse can occur: either recreational misuse, wherein the drug is taken to achieve a high, or when the drug is continued long-term against medical advice. Zopiclone is as addictive as or may be more addictive than benzodiazepines. Those with a history of substance misuse or mental health disorders may be at an increased risk of high-dose zopiclone misuse. High-dose misuse of zopiclone and increasing popularity amongst people who use substances who have been prescribed with zopiclone was shown in the 1990s. The symptoms of zopiclone addiction can include depression, dysphoria, hopelessness, slow thoughts, social isolation, worrying, sexual anhedonia, and nervousness. Zopiclone and other sedative hypnotic drugs are detected frequently in cases of people suspected of driving under the influence of drugs. Other sedating drugs, including benzodiazepines and zolpidem, are also found in high numbers of suspected drugged drivers.
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.
No. Freeze-drying removes water but does not reliably kill microorganisms. Sterile lyophilized products are typically prepared aseptically before freezing or are sterilized by a validated method. Microbial control depends on the entire manufacturing process.