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Veronal
Barbital (or barbitone), marketed under the brand names Veronal for the pure acid and Medinal for the sodium salt, was the first commercially available barbiturate. It was used as a sleeping aid (hypnotic) from 1903 until the mid-1950s. The chemical names for barbital are diethylmalonyl urea or diethylbarbituric acid; hence, the sodium salt (known as medinal, a genericised trademark in the United Kingdom) is known also as sodium diethylbarbiturate. Synthesis Barbital, then called "Veronal", was first synthesized in 1902 by German chemists Emil Fischer and Joseph von Mering, who published their discovery in 1903. Barbital was prepared by condensing diethylmalonic ester with urea in the presence of sodium ethoxide, or by adding at least two molar equivalents of ethyl iodide to the silver salt of malonylurea (barbituric acid) or possibly to a basic solution of the acid. The result was an odorless, slightly bitter, white crystalline powder. Its introduction followed the investig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barbital Synthese
Barbital (or barbitone), marketed under the brand names Veronal for the pure acid and Medinal for the sodium salt, was the first commercially available barbiturate. It was used as a sleeping aid (hypnotic) from 1903 until the mid-1950s. The chemical names for barbital are diethylmalonyl urea or diethylbarbituric acid; hence, the sodium salt (known as medinal, a genericised trademark in the United Kingdom) is known also as sodium diethylbarbiturate. Synthesis Barbital, then called "Veronal", was first synthesized in 1902 by German chemists Emil Fischer and Joseph von Mering, who published their discovery in 1903. Barbital was prepared by condensing diethylmalonic ester with urea in the presence of sodium ethoxide, or by adding at least two molar equivalents of ethyl iodide to the silver salt of malonylurea (barbituric acid) or possibly to a basic solution of the acid. The result was an odorless, slightly bitter, white crystalline powder. Its introduction followed the investiga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Emil Fischer
Hermann Emil Louis Fischer (; 9 October 1852 – 15 July 1919) was a German chemist and 1902 recipient of the Nobel Prize in Chemistry. He discovered the Fischer esterification. He also developed the Fischer projection, a symbolic way of drawing asymmetric carbon atoms. He also hypothesized lock and key mechanism of enzyme action. He never used his first given name, and was known throughout his life simply as Emil Fischer. Early years and career Fischer was born in Euskirchen, near Cologne, the son of Laurenz Fischer, a businessman, and his wife Julie Poensgen. After graduating he wished to study natural sciences, but his father compelled him to work in the family business until determining that his son was unsuitable. Fischer then attended the University of Bonn in 1871, but switched to the University of Strasbourg in 1872. He earned his doctorate in 1874 under Adolf von Baeyer with his study of phthaleins, and was appointed to a position at the university. After eight ye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barbiturate
Barbiturates are a class of depressant drugs that are chemically derived from barbituric acid. They are effective when used medically as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological addiction potential as well as overdose potential among other possible adverse effects. They have been used recreationally for their anxiolytic and sedative effects, and are thus controlled in most countries due to the risks associated with such use. Barbiturates have largely been replaced by benzodiazepines and nonbenzodiazepines ("Z-drugs") in routine medical practice, particularly in the treatment of anxiety disorders and insomnia, because of the significantly lower risk of overdose, and the lack of an antidote for barbiturate overdose. Despite this, barbiturates are still in use for various purposes: in general anesthesia, epilepsy, treatment of acute migraines or cluster headaches, acute tension headaches, euthanasia, capital punishment, and assisted suicid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insomnia
Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, irritability, and a depressed mood. It may result in an increased risk of motor vehicle collisions, as well as problems focusing and learning. Insomnia can be short term, lasting for days or weeks, or long term, lasting more than a month. The concept of the word insomnia has two possibilities: insomnia disorder and insomnia symptoms, and many abstracts of randomized controlled trials and systematic reviews often underreport on which of these two possibilities the word insomnia refers to. Insomnia can occur independently or as a result of another problem. Conditions that can result in insomnia include psychological stress, chronic pain, heart failure, hyperthyroidism, heartburn, restless leg syndrome, menopause, certain medications, and d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buffer Solution
A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many living systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood, and bicarbonate also acts as a buffer in the ocean. Principles of buffering Buffer solutions resist pH change because of a chemical equilibrium between the weak acid HA and its conjugate base A−: When some strong acid is added to an equilibrium mixture of the weak acid and its conjugate base, hydrogen ions (H+) are added, and the equilibrium is shifted to the left, in accordance with Le Chatelier's principle. Because of this, the hydrogen io ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclodextrin
Cyclodextrins are a family of cyclic oligosaccharides, consisting of a macrocyclic ring of glucose subunits joined by α-1,4 glycosidic bonds. Cyclodextrins are produced from starch by enzymatic conversion. They are used in food, pharmaceutical, drug delivery, and chemical industries, as well as agriculture and environmental engineering. Cyclodextrins are composed of 5 or more α-D-glucopyranoside units linked 1->4, as in amylose (a fragment of starch). Typical cyclodextrins contain a number of glucose monomers ranging from six to eight units in a ring, creating a cone shape: * α (alpha)-cyclodextrin: 6 glucose subunits * β (beta)-cyclodextrin: 7 glucose subunits * γ (gamma)-cyclodextrin: 8 glucose subunits The largest well-characterized cyclodextrin contains 32 1,4-anhydroglucopyranoside units. Poorly-characterized mixtures, containing at least 150-membered cyclic oligosaccharides are also known. Applications Drug delivery Cyclodextrins are ingredients in more than 30 d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoisomerization
In chemistry, photoisomerization is a form of isomerization induced by photoexcitation. Both reversible and irreversible photoisomerizations are known for photoswitchable compounds. The term "photoisomerization" usually, however, refers to a reversible process. Applications Photoisomerization of the compound retinal in the eye allows for vision. Photoisomerizable substrates have been put to practical use, for instance, in pigments for rewritable CDs, DVDs, and 3D optical data storage solutions. In addition, interest in photoisomerizable molecules has been aimed at molecular devices, such as molecular switches, molecular motors, and molecular electronics. Another class of device that uses the photoisomerization process is as an additive in liquid crystals to change their linear and nonlinear properties. Due to the photoisomerization is possible to induce a molecular reorientation in the liquid crystal bulk, which is used in holography, as spatial filter or optical switching. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GABAA Receptor
The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon opening, the GABAA receptor on the postsynaptic cell is selectively permeable to chloride ions (Cl−) and, to a lesser extent, bicarbonate ions (HCO3−). Depending on the membrane potential and the ionic concentration difference, this can result in ionic fluxes across the pore. If the membrane potential is higher than the equilibrium potential (also known as the reversal potential) for chloride ions, when the receptor is activated Cl− will flow into the cell. This causes an inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring at the postsynaptic cell. The reversal potential of the GABAA-mediated inhibitory postsynaptic potential (IPSP) in normal solution is −70 mV, contrasting the GABAB IPSP (-100 mV). T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photopharmacology
Photopharmacology, an emerging approach in medicine, involves activating and deactivating photoswitchable molecules with light for target drug delivery. Clinicians use the energy of light to change the shape and chemical properties of a drug, resulting in different biological activity. This is done to ultimately achieve control of when and where drugs are active in a reversible manner, and to prevent side effects and exposure to the environment of antibiotics. Switching drugs "on" and "off" is achieved by introducing photoswitches such as azobenzene, spiropyran or diarylethene into the drug. Photopharmalogical drugs with a photoswitch have two different states, which light can toggle between. Since both states have a different structure, the activity of the drug is different, hence the "on" and "off" state of the drug. An example is photostatin, which is an inhibitor that can be switched on and off ''in vivo'' to optically control microtubule dynamics. See also * Optogenetics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stenhouse Adduct
Stenhouse may refer to: Places Australia * Stenhouse Bay, South Australia, a township in South Australia Hong Kong * Mount Stenhouse on Lamma Island, Hong Kong Scotland * Stenhouse, Edinburgh, a community in the City of Edinburgh South Georgia and the South Sandwich Islands * Stenhouse Peak, a peak on South Georgia island People *Alex Stenhouse (1910–1992), New Zealand footballer * Andrew G. Stenhouse (1869–1950) Scottish businessman, geologist, and astronomer * Anthony Maitland Stenhouse (1849–1927), Scottish-born Canadian politician * Bart Stenhouse (born 1981), Australian jazz fusion musician and teacher * Bobby Stenhouse (1924–1990), British lawn and indoor bowls competitor *Dave Stenhouse (born 1933), American baseball player; father of Mike Stenhouse *David Stenhouse (born 1932), British evolutionary biologist and ethologist * Fanny Stenhouse (1829–1904), Jersey-born American pioneer and Mormon, later LDS opponent and writer; wife of T. B. H. Stenhouse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transatlantic Flight Of Alcock And Brown
British aviators John Alcock and Arthur Brown made the first non-stop transatlantic flight in June 1919. They flew a modified First World War Vickers Vimy bomber from St. John's, Newfoundland, to Clifden, County Galway, Ireland. The Secretary of State for Air, Winston Churchill, presented them with the ''Daily Mail'' prize for the first crossing of the Atlantic Ocean by aeroplane in "less than 72 consecutive hours." A small amount of mail was carried on the flight, making it the first transatlantic airmail flight. The two aviators were awarded the honour of Knight Commander of the Most Excellent Order of the British Empire (KBE) by King George V at Windsor Castle a week later. Background John Alcock was born in 1892 in Basford House on Seymour Grove, Firswood, Manchester, England. Known to his family and friends as "Jack", he first became interested in flying at the age of seventeen and gained his pilot's licence in November 1912. Alcock was a regular competitor in aircr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Whitten Brown
Lieutenant-Colonel Sir Arthur Whitten Brown, (23 July 1886 – 4 October 1948) was a British military officer and aviator who flew as navigator of the first successful non-stop transatlantic flight with pilot John Alcock in June 1919. Biography Arthur Whitten Brown was born in Glasgow to American parents; his father had been sent to Scotland to evaluate the feasibility of siting a Westinghouse factory on Clydeside. The factory was eventually sited in Trafford Park in Stretford, Manchester, and the family subsequently relocated there. Brown began his career in engineering before the outbreak of World War I and undertook an apprenticeship with British Westinghouse in Manchester. In 1914, he enlisted in the ranks of the University and Public Schools Brigade (UPS) for which he had to take out British citizenship. The ranks of the UPS were full of potential officers and Brown was one of those who sought a commission to become a Second Lieutenant in the 3rd (Special Reserve) Batt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
