Misplaced Pages

#623376

25-451: Jenko is a Slovene surname. Notable people with the surname include: Ana Jenko, the birth name of Ana Štěrba-Böhm , Slovene chemist Davorin Jenko (1835–1914), Slovene composer Simon Jenko (1835–1869), Slovene poet, lyricist and writer Jenko Award , Slovene literary award Fictional characters Greg Jenko, a character from

50-693: A direct enrollment at a university, since girls at that time were not permitted as regular students in grammar schools. After graduating, she enrolled in the study of philosophy at the philosophical faculty of the Charles-Ferdinand University in Prague in 1906, where she stated in the enrollment form that she had also attended higher courses for women at the St Petersburg University earlier. For five semesters, she studied chemistry as an extraordinary student, then as

75-435: A regular student. Among her teachers were Bohuslav Brauner (theoretical and physical chemistry), Bohumil Kužma (anorganic chemistry) and her later husband Jan Stanislav Štěrba-Böhm (history of chemistry), while also classes in mineralogy, experimental physics, mathematics, history of philosophy, Czech and German language were noted in her curriculum. She probably spent the 1911 summer semester preparing her doctoral thesis on

100-450: Is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes but also in tamarinds , bananas , avocados , and citrus . Its salt , potassium bitartrate , commonly known as cream of tartar, develops naturally in the process of fermentation . Potassium bitartrate is commonly mixed with sodium bicarbonate and is sold as baking powder used as a leavening agent in food preparation. The acid itself

125-496: Is about 7.5 grams/kg for a human, 5.3 grams/kg for rabbits, and 4.4 grams/kg for mice. Given this figure, it would take over 500 g (18 oz) to kill a person weighing 70 kg (150 lb) with 50% probability, so it may be safely included in many foods, especially sour-tasting sweets . As a food additive , tartaric acid is used as an antioxidant with E number E334 ; tartrates are other additives serving as antioxidants or emulsifiers . When cream of tartar

150-407: Is added to foods as an antioxidant E334 and to impart its distinctive sour taste. Naturally occurring tartaric acid is a useful raw material in organic chemical synthesis . Tartaric acid, an alpha-hydroxy- carboxylic acid , is diprotic and aldaric in acid characteristics and is a dihydroxyl derivative of succinic acid . Tartaric acid has been known to winemakers for centuries. However,

175-444: Is added to water, a suspension results which serves to clean copper coins very well, as the tartrate solution can dissolve the layer of copper(II) oxide present on the surface of the coin. The resulting copper(II)-tartrate complex is easily soluble in water. Tartaric acid may be most immediately recognizable to wine drinkers as the source of "wine diamonds", the small potassium bitartrate crystals that sometimes form spontaneously on

200-611: Is also present in the leaves and pods of Pelargonium plants and beans . Tartaric acid and its derivatives have a plethora of uses in the field of pharmaceuticals. For example, it has been used in the production of effervescent salts, in combination with citric acid, to improve the taste of oral medications. The potassium antimonyl derivative of the acid known as tartar emetic is included, in small doses, in cough syrup as an expectorant . Tartaric acid also has several applications for industrial use. The acid has been observed to chelate metal ions such as calcium and magnesium. Therefore,

225-681: Is different from Wikidata All set index articles Ana %C5%A0t%C4%9Brba-B%C3%B6hm Ana Jenko was born in Ljubljana , then part of Austria-Hungary , to a highly educated family. Her father was the physician Ludvik Jenko and her mother Terezija Jenko (née Lenče) who was also an educated woman, having studied with Ursulines in Ljubljana and in Bavaria , as well as spending a year in Moscow . She assisted her husband in his practice, and

250-420: Is formed when dextro -Tartaric acid is heated in water at 165 °C for about 2 days. meso -Tartaric acid can also be prepared from dibromosuccinic acid using silver hydroxide: meso -Tartaric acid can be separated from residual racemic acid by crystallization, the racemate being less soluble. L-(+)-tartaric acid, can participate in several reactions. As shown the reaction scheme below, dihydroxymaleic acid

275-409: Is industrially produced in the largest amounts. It is obtained from lees , a solid byproduct of fermentations. The former byproducts mostly consist of potassium bitartrate ( KHC 4 H 4 O 6 ). This potassium salt is converted to calcium tartrate ( CaC 4 H 4 O 6 ) upon treatment with calcium hydroxide ( Ca(OH) 2 ): In practice, higher yields of calcium tartrate are obtained with

SECTION 10

#1732790950624

300-424: Is produced upon treatment of L-(+)-tartaric acid with hydrogen peroxide in the presence of a ferrous salt. Dihydroxymaleic acid can then be oxidized to tartronic acid with nitric acid. Important derivatives of tartaric acid include: Tartaric acid is a muscle toxin , which works by inhibiting the production of malic acid , and in high doses causes paralysis and death. The median lethal dose (LD 50 )

325-744: The Jump Street franchise See also [ edit ] Eleonora Jenko Groyer (1879–1959), Slovenian physician Jenčo [REDACTED] Surname list This page lists people with the surname Jenko . If an internal link intending to refer to a specific person led you to this page, you may wish to change that link by adding the person's given name (s) to the link. Retrieved from " https://en.wikipedia.org/w/index.php?title=Jenko&oldid=1220569157 " Categories : Surnames Surnames of Slovene origin Hidden categories: Articles with short description Short description

350-437: The cork or bottom of the bottle. These "tartrates" are harmless, despite sometimes being mistaken for broken glass, and are prevented in many wines through cold stabilization (which is not always preferred since it can change the wine's profile). The tartrates remaining on the inside of aging barrels were at one time a major industrial source of potassium bitartrate. Tartaric acid plays an important role chemically, lowering

375-411: The acid has served in the farming and metal industries as a chelating agent for complexing micronutrients in soil fertilizer and for cleaning metal surfaces consisting of aluminium, copper, iron, and alloys of these metals, respectively. While tartaric acid is well-tolerated by humans and lab animals, an April 2021 letter to the editor of JAVMA hypothesized that the tartaric acid in grapes could be

400-460: The addition of calcium sulfate . Calcium tartrate is then converted to tartaric acid by treating the salt with aqueous sulfuric acid: Racemic tartaric acid can be prepared in a multistep reaction from maleic acid . In the first step, the maleic acid is epoxidized by hydrogen peroxide using potassium tungstate  [ de ] as a catalyst. In the next step, the epoxide is hydrolyzed. A mixture of racemic acid and meso -tartaric acid

425-548: The chemical process for extraction was developed in 1769 by the Swedish chemist Carl Wilhelm Scheele . Tartaric acid played an important role in the discovery of chemical chirality . This property of tartaric acid was first observed in 1832 by Jean Baptiste Biot , who observed its ability to rotate polarized light . Louis Pasteur continued this research in 1847 by investigating the shapes of sodium ammonium tartrate crystals, which he found to be chiral. By manually sorting

450-455: The couple actively participated in Slovene cultural life as promotors of Pan-Slavism . They had four children. All siblings obtained higher education, most notably Ana's sister Eleonora who went on to become the first Slovene female physician. Ana's early education is uncertain; she is said to have attended the 1st grammar school in Ljubljana as a private student, which was the only way for

475-422: The differently shaped crystals, Pasteur was the first to produce a pure sample of levotartaric acid. Naturally occurring form of the acid is dextro tartaric acid or L -(+)-tartaric acid (obsolete name d -tartaric acid). Because it is available naturally, it is cheaper than its enantiomer and the meso isomer . The dextro and levo prefixes are archaic terms. Modern textbooks refer to

500-479: The natural form as (2 R ,3 R )-tartaric acid ( L -(+)-tartaric acid) , and its enantiomer as (2 S ,3 S )-tartaric acid ( D -(-)-tartaric acid) . The meso diastereomer is referred to as (2 R ,3 S )-tartaric acid or (2 S ,3 R )-tartaric acid. Tartaric acid in Fehling's solution binds to copper(II) ions, preventing the formation of insoluble hydroxide salts. The L -(+)-tartaric acid isomer of tartaric acid

525-649: The pH of fermenting "must" to a level where many undesirable spoilage bacteria cannot live, and acting as a preservative after fermentation . In the mouth, tartaric acid provides some of the tartness in the wine, although citric and malic acids also play a role. Grapes and tamarinds have the highest levels of tartaric acid concentration. Other fruits with tartaric acid are bananas , avocados , prickly pear fruit, apples , cherries , papayas , peaches , pears , pineapples , strawberries , mangoes and citrus fruits . Trace amounts of tartaric acid have been found in cranberries and other berries . Tartaric acid

SECTION 20

#1732790950624

550-591: The time, but her scientific contribution is attested in the acknowledgements section. In 1914, their son Jan Peter was born. Jan Peter Štěrba-Böhm became a chemist as well and, like his mother, collaborated with his father on chemical studies. He received his PhD in chemistry in 1937. Ana Štěrba-Böhm died of cancer on 22 July 1936 in Prague, and is buried at the Vinohrady Cemetery there. Her husband died in 1938. Tartaric acid Tartaric acid

575-554: The topic of determining and separating three organic acids: succinic , malic and tartaric acid . On 22 July 1911, she received her doctorate from the Philosophical Faculty of the Carl-Ferdinand University in Prague (Czech branch) after major rigorosums in chemistry and physics, and minor in philosophy, with the thesis Studie o stanovení a dělení kyselin: jantarové, jablečné a vinné . This

600-473: The turn of the century, likely arranged Ana's training in Marie Curie's laboratory. However, Ana Štěrba-Böhm did not pursue independent research after the marriage, but supported her husband's research on the properties of scandium . She was not signed as a co-author of the paper he published in 1914 in the journal Zeitschrift für Electrochemie und Angewandte Physikalische Chemie , as was common practice at

625-503: Was noted by several contemporary Slovene newspapers and earned her the distinction of being the first Slovene woman to receive a doctorate in science. Next year, on 4 December 1912, Ana Jenko married her professor Jan Stanislav Štěrba-Böhm and took both his surnames, so she began using the name Ana (Anna) Štěrba-Böhm. Jan Stanislav, having completed his studies at Sorbonne in Paris under Henri Moissan , Pierre Curie and Marie Curie at

#623376