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Para-Dimethylaminobenzaldehyde
''para''-Dimethylaminobenzaldehyde is an organic compound containing amine and aldehyde moieties which is used in Ehrlich's reagent and Kovac's reagent to test for indoles. The carbonyl group typically reacts with the electron rich 2-position of the indole but may also react at the C-3 or N-1 positions. It may also be used for determination of hydrazine. Ehrlich's reagent ''para''-Dimethylaminobenzaldehyde is the main ingredient in Ehrlich's reagent. It acts as a strong electrophile which reacts with the electron-rich α-carbon (2-position) of indole rings to form a blue-colored adduct. It can be used to detect the presence of indole alkaloids. Not all indole alkaloids give a colored adduct as result of steric hindrance which does not allow the reaction to proceed. Ehrlich's reagent is also used as a stain in thin layer chromatography and as a reagent to detect urobilinogen in fresh, cool urine. If a urine sample is left to oxidize in air to form urobilin the reagent will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indole Test
The indole test is a biochemical test performed on bacterial species to determine the ability of the organism to convert tryptophan into indole. This division is performed by a chain of a number of different intracellular enzymes, a system generally referred to as "tryptophanase." Biochemistry Indole is generated by reductive deamination from tryptophan via the intermediate molecule indolepyruvic acid. Tryptophanase catalyzes the deamination reaction, during which the amine (-NH2) group of the tryptophan molecule is removed. Final products of the reaction are indole, pyruvic acid, ammonium (NH4+) and energy. Pyridoxal phosphate is required as a coenzyme. Performing a test Like many biochemical tests on bacteria, results of an indole test are indicated by a change in color following a reaction with an added reagent. Pure bacterial culture must be grown in sterile tryptophan or peptone broth for 24–48 hours before performing the test. Following incubation, five drops of K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ehrlich's Reagent
Ehrlich's reagent or Ehrlich reagent is a reagent containing ''p''-dimethylaminobenzaldehyde (DMAB) and thus can act as an indicator to presumptively identify indoles and urobilinogen. Several Ehrlich tests use the reagent in a medical test; some are drug tests and others contribute to diagnosis of various diseases or adverse drug reactions. It is named after Nobel Prize winner Paul Ehrlich who used it to distinguish typhoid from simple diarrhoea. The Ehrlich reagent works by binding to the C2 position of two indole moieties to form a resonance stabilised carbenium ion compound. Medical testing Ehrlich reagent can be used to detect urobilinogen, which can indicate jaundice or other liver-related issues. A very common Ehrlich test is a simple spot test to identify possible psychoactive compounds such as tryptamines (e.g. DMT) and lysergamides (e.g. LSD). It gives a negative test-result for 25I-NBOMe and many other non-indole-related psychoactives. The reagent will also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urobilinogen
Urobilinogen is a yellow by-product of bilirubin reduction. It is formed in the intestines by the bacterial enzyme bilirubin reductase. About half of the urobilinogen formed is reabsorbed and taken up via the portal vein to the liver, enters circulation and is excreted by the kidney. Increased amounts of bilirubin are formed in hemolysis, which generates increased urobilinogen in the gut. In liver disease (such as hepatitis), the intrahepatic urobilinogen cycle is inhibited also increasing urobilinogen levels. Urobilinogen is converted to the yellow pigmented urobilin apparent in urine. The urobilinogen in the intestine is directly reduced to brownish colour stercobilin, which gives the feces their characteristic color. It can also be reduced to stercobilinogen, which can then be further oxidized to stercobilin. In biliary obstruction, below-normal amounts of conjugated bilirubin reach the intestine for conversion to urobilinogen. With limited urobilinogen available for reabsorpt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amine
In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of electrons. Amines can also exist as hetero cyclic compounds. Aniline is the simplest aromatic amine, consisting of a benzene ring bonded to an amino group. Amines are classified into three types: primary (1°), secondary (2°), and tertiary (3°) amines. Primary amines (1°) contain one alkyl or aryl substituent and have the general formula RNH2. Secondary amines (2°) have two alkyl or aryl groups attached to the nitrogen atom, with the general formula R2NH. Tertiary amines (3°) contain three substituent groups bonded to the nitrogen atom, and are represented by the formula R3N. The functional group present in primary amines is called the amino group. Classification of amines Amines can be classified according to the nature and number o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frankincense
Frankincense, also known as olibanum (), is an Aroma compound, aromatic resin used in incense and perfumes, obtained from trees of the genus ''Boswellia'' in the family (biology), family Burseraceae. The word is from Old French ('high-quality incense'). There are several species of ''Boswellia'' that produce true frankincense: ''Boswellia sacra'' (synonym (taxonomy), syn. ''B. bhaw-dajiana'', syn. ''B. carteri''), ''Boswellia frereana, B. frereana'', ''Boswellia serrata, B. serrata'' (''B. thurifera''), and ''Boswellia papyrifera, B. papyrifera''. Resin from each is available in various grades, which depends on the time of harvesting. The resin is hand-sorted for quality. Etymology The English word ''frankincense'' derives from the Old French expression , meaning 'true incense', maybe with the sense of 'high quality incense'. The adjective in Old French meant 'noble, true', in this case perhaps 'pure'; although ''franc'' is ultimately derived from the tribal name of the Franks, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isaac Asimov
Isaac Asimov ( ; – April 6, 1992) was an Russian-born American writer and professor of biochemistry at Boston University. During his lifetime, Asimov was considered one of the "Big Three" science fiction writers, along with Robert A. Heinlein and Arthur C. Clarke. A prolific writer, he wrote or edited more than 500 books. He also wrote an estimated 90,000 letters and postcards. Best known for his hard science fiction, Asimov also wrote mystery fiction, mysteries and fantasy, as well as popular science and other non-fiction. Asimov's most famous work is the ''Foundation (book series), Foundation'' series, the first three books of which won the one-time Hugo Award for "Best All-Time Series" in 1966. His other major series are the ''Galactic Empire series, Galactic Empire'' series and the ''Robot series, Robot'' series. The ''Galactic Empire'' novels are set in the much earlier history of the same fictional universe as the ''Foundation'' series. Later, with ''Foundation an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Magazine Of Fantasy And Science Fiction
''The Magazine of Fantasy & Science Fiction'' (usually referred to as ''F&SF'') is a U.S. fantasy and science-fiction magazine, first published in 1949 by Mystery House, a subsidiary of Lawrence Spivak's Mercury Press. Editors Anthony Boucher and J. Francis McComas had approached Spivak in the mid-1940s about creating a fantasy companion to Spivak's existing mystery title, '' Ellery Queen's Mystery Magazine''. The first issue was titled ''The Magazine of Fantasy'', but the decision was quickly made to include science fiction as well as fantasy, and the title was changed correspondingly with the second issue. ''F&SF'' was quite different in presentation from the existing science-fiction magazines of the day, most of which were in pulp format: it had no interior illustrations, no letter column, and text in a single-column format, which in the opinion of science-fiction historian Mike Ashley "set ''F&SF'' apart, giving it the air and authority of a superior magazine". ''F&S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adding A Dimension
''Adding a Dimension'' is a collection of seventeen scientific essays by American writer and scientist Isaac Asimov. It was the third of a series of books collecting essays from ''The Magazine of Fantasy and Science Fiction''. It was first published by Doubleday & Company Doubleday is an American publishing company. It was founded as the Doubleday & McClure Company in 1897. By 1947, it was the largest book publisher in the United States. It published the work of mostly U.S. authors under a number of imprints and ... in 1964. Contents *Part I: Mathematics **T-Formation (August 1963) **One, Ten, Buckle My Shoe (December 1962) **Varieties of the Infinite (September 1959) **A Piece of Pi (May 1960) **Tools of the Trade (September 1960) **The Imaginary that Isn't (March 1961) **Pre-Fixing It Up (November 1962) *Part II: Physics **The Rigid Vacuum (April 1963) **The Light that Failed (June 1963) **The Light Fantastic (August 1962) *Part III: Chemistry **Slow Burn (October 1962) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Etymology
Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. Most directly tied to historical linguistics, philology, and semiotics, it additionally draws upon comparative semantics, morphology, pragmatics, and phonetics in order to attempt a comprehensive and chronological catalogue of all meanings and changes that a word (and its related parts) carries throughout its history. The origin of any particular word is also known as its ''etymology''. For languages with a long written history, etymologists make use of texts, particularly texts about the language itself, to gather knowledge about how words were used during earlier periods, how they developed in meaning and form, or when and how they entered the language. Etymologists also apply the methods of comparative linguistics to reconstruct in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Irish Washerwoman
"The Irish Washerwoman" is a traditional jig known to have been played throughout Britain and Ireland and in North America. Although usually considered an Irish tune, some scholars claim that it is English in origin, derived from the seventeenth-century tune " Dargason". According to the "tunearch" website, the earliest appearance is in Robert Petrie's "Collection of Strathspeys Reels and Country Dances" 1790. A different page on the same website mentions that a version by Niel Gow appeared in 1792 in "A Third Collection of Strathspey Reels". The second half of the tune is identical to "The Star at Liwis" printed about 1730 in "Caledonian Country Dances" by J Walsh. The earliest recording appears to be Patsy Touhey in 1907, available on "The Piping of Patsy Touhey". This later became available on the album "The Piping of Patsy Touhey" in 2005 on the Na Píobairí Uilleann label. A more famous recording is on the album "In Full Spate" by Paddy Glackin (1991). Scan Tester (1887-1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, projected to rise to 158 million at mid 2025, Java is the world's List of islands by population, most populous island, home to approximately 55.7% of the Demographics of Indonesia, Indonesian population (only approximately 44.3% of Indonesian population live outside Java). Indonesia's capital city, Jakarta, is on Java's northwestern coast. Many of the best known events in Indonesian history took place on Java. It was the centre of powerful Hindu-Buddhist empires, the Islamic sultanates, and the core of the colonial Dutch East Indies. Java was also the center of the History of Indonesia, Indonesian struggle for independence during the 1930s and 1940s. Java dominates Indonesia politically, economically and culturally. Four of Indonesia's eig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrophotometric
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses photometers, known as spectrophotometers, that can measure the intensity of a light beam at different wavelengths. Although spectrophotometry is most commonly applied to ultraviolet, Visible spectrum, visible, and infrared radiation, modern spectrophotometers can interrogate wide swaths of the electromagnetic spectrum, including x-ray, ultraviolet, Visible spectrum, visible, infrared, or microwave wavelengths. Overview Spectrophotometry is a tool that hinges on the quantitative analysis of molecules depending on how much light is absorbed by colored compounds. Important features of spectrophotometers are spectral bandwidth (the range of colors it can transmit through the test sample), the percentage of sample transmission, the logarithmic range of sample absorptio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
