The citric acid cycle – known as the TCA cycle or the Krebs cycle – is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates and proteins, into adenosine triphosphate and carbon dioxide. In addition, the cycle provides precursors of certain amino acids, as well as the reducing agent NADH, that are used in numerous other reactions, its central importance to many biochemical pathways suggests that it was one of the earliest established components of cellular metabolism and may have originated abiogenically. Though it is branded as a'cycle', it is not necessary for metabolites to follow only one specific route; the name of this metabolic pathway is derived from the citric acid, consumed and regenerated by this sequence of reactions to complete the cycle. The cycle consumes acetate and water, reduces NAD+ to NADH, produces carbon dioxide as a waste byproduct; the NADH generated by the citric acid cycle is fed into the oxidative phosphorylation pathway.
The net result of these two linked pathways is the oxidation of nutrients to produce usable chemical energy in the form of ATP. In eukaryotic cells, the citric acid cycle occurs in the matrix of the mitochondrion. In prokaryotic cells, such as bacteria, which lack mitochondria, the citric acid cycle reaction sequence is performed in the cytosol with the proton gradient for ATP production being across the cell's surface rather than the inner membrane of the mitochondrion; the overall yield of energy-containing compounds from the TCA cycle is three NADH, one FADH2, one GTP. Several of the components and reactions of the citric acid cycle were established in the 1930s by the research of Albert Szent-Györgyi, who received the Nobel Prize in Physiology or Medicine in 1937 for his discoveries pertaining to fumaric acid, a key component of the cycle, he was able to make this discovery successful with the help of pigeon breast muscle. Because this tissue maintains its oxidative capacity well after breaking down in the "Latapie" mill and releasing in aqueous solutions, breast muscle of the pigeon was well qualified for the study of oxidative reactions.
The citric acid cycle itself was identified in 1937 by Hans Adolf Krebs and William Arthur Johnson while at the University of Sheffield, for which the former received the Nobel Prize for Physiology or Medicine in 1953, for whom the cycle is sometimes named. The citric acid cycle is a key metabolic pathway that connects carbohydrate and protein metabolism; the reactions of the cycle are carried out by eight enzymes that oxidize acetate, in the form of acetyl-CoA, into two molecules each of carbon dioxide and water. Through catabolism of sugars and proteins, the two-carbon organic product acetyl-CoA is produced which enters the citric acid cycle; the reactions of the cycle convert three equivalents of nicotinamide adenine dinucleotide into three equivalents of reduced NAD+, one equivalent of flavin adenine dinucleotide into one equivalent of FADH2, one equivalent each of guanosine diphosphate and inorganic phosphate into one equivalent of guanosine triphosphate. The NADH and FADH2 generated by the citric acid cycle are, in turn, used by the oxidative phosphorylation pathway to generate energy-rich ATP.
One of the primary sources of acetyl-CoA is from the breakdown of sugars by glycolysis which yield pyruvate that in turn is decarboxylated by the pyruvate dehydrogenase complex generating acetyl-CoA according to the following reaction scheme: CH3CCO−pyruvate + HSCoA + NAD+ → CH3CSCoAacetyl-CoA + NADH + CO2The product of this reaction, acetyl-CoA, is the starting point for the citric acid cycle. Acetyl-CoA may be obtained from the oxidation of fatty acids. Below is a schematic outline of the cycle: The citric acid cycle begins with the transfer of a two-carbon acetyl group from acetyl-CoA to the four-carbon acceptor compound to form a six-carbon compound; the citrate goes through a series of chemical transformations, losing two carboxyl groups as CO2. The carbons lost as CO2 originate from what was oxaloacetate, not directly from acetyl-CoA; the carbons donated by acetyl-CoA become part of the oxaloacetate carbon backbone after the first turn of the citric acid cycle. Loss of the acetyl-CoA-donated carbons as CO2 requires several turns of the citric acid cycle.
However, because of the role of the citric acid cycle in anabolism, they might not be lost, since many citric acid cycle intermediates are used as precursors for the biosynthesis of other molecules. Most of the energy made available by the oxidative steps of the cycle is transferred as energy-rich electrons to NAD+, forming NADH. For each acetyl group that enters the citric acid cycle, three molecules of NADH are produced; the citric acid cycle includes a series of oxidation reduction reaction in mitochondria. In addition, electrons from the succinate oxidation step are transferred first to the FAD cofactor of succinate dehydrogenase, reducing it to FADH2, to ubiquinone in the mitochondrial membrane, reducing it to ubiquinol, a substrate of the electron transfer chain at the level of Complex III. For every NADH and FADH2 that are produced in the citric acid cycle, 2.5 and 1.5 ATP molecules are generated in oxidative phosphorylation, respectively. At the end of each cycle, the four-carbon oxaloacetat
An air diffuser or membrane diffuser is an aeration device in the shape of a disc, tube or plate, used to transfer air and with that oxygen into the sewage or industrial wastewater. Oxygen is required by microorganisms/bacteria residents in the water to break down the pollutants. Diffusers use either rubber membranes or ceramic elements and produce either fine or coarse bubbles. Diffusers are referred to as either: Fine Bubble/Fine Pore Coarse BubbleOther diffused aeration devices include: jet aerators, U tubes. Typical efficiency of a full floor coverage diffused aeration system in clean water is 2%/ft submergence or 6.6%/m submergence. When converted to mass transfer into process or dirty water, it is closer to about half of those figures. Manufacturers of fine bubble systems have supported claims that the type and size of "pores" have a great effect on efficiency of a diffused aeration system. Diffusers are connected to a piping system, supplied with pressurized air by a blower; this system is referred to as a diffused aeration system or aeration grid.
There are two main types of diffused aeration systems and fixed grid, that are designed to serve different purposes. In the case of a plant with a single tank, a retrievable system is desirable, in order to avoid stopping operation of the plant when maintenance is required on the aeration system. Fixed systems, on the other hand, are less costly, more efficient because it is easier to make full use of the floor. List of waste-water treatment technologies
The Curonian language, or Old Curonian, is a nearly unattested Baltic extinct language spoken by the Curonians, a Baltic tribe who inhabited the Courland Peninsula and the nearby Baltic shore. Curonian was a Baltic language. Linguist Eduard Vääri argues; the attested local Finnic language, may be the source of Finnic elements in Curonian. In 1912 Latvian linguist Jānis Endzelīns proved that Curonian was a Baltic language. Old Curonian disappeared in the course of the 16th century, leaving substrata in western dialects of the Latvian and Lithuanian, namely the Samogitian dialect. No written documents in this language are known, but some ancient Lithuanian texts from western regions show some Curonian influence. According to Lithuanian linguist Zigmas Zinkevičius and intense Curonian–Lithuanian bilingualism existed. There are attested names of Curonian noblemen such as: Lammechinus, Veltūnas, Tvertikis, Saveidis. Samogitian words such as kuisis, pylė, cyrulis, zuikis, kūlis, pūrai considered to be of Curonian origin.
After the dissolution of the Soviet Union, the Baltic states saw a revival of scientific and cultural interest in extinct Baltic languages and tribes, including Yotvingian and Old Prussian. Kursenieki language Ambrassat, August "Die Provinz Ostpreußen", Frankfurt/ Main 1912 Endzelin, J.: Über die Nationalität und Sprache der Kuren, in Finnisch-Ungarische Forschungen, XII, 1912 Gaerte, Wilhelm "Urgeschichte Ostpreussens", Königsberg 1929 Gimbutas, Marija "Die Balten", München-Berlin 1983 Kurschat, Heinrich A.: Das Buch vom Memelland, Siebert Oldenburg 1968 Kwauka, Pietsch, Richard: Kurisches Wörterbuch, Verlag Ulrich Camen Berlin, 1977, ISBN 3-921515-03-3 Kwauka, Paul: Namen des Memellandes/ Unsere „fremdartigen“ Familiennamen, Archiv AdM, Oldenburg Lepa, Gerhard "Die Schalauer", Tolkemita-Texte Dieburg 1997 Mortensen, Hans und Gertrud "Die Besiedlung des nordöstlichen Ostpreußens bis zum Beginn des 17. Jahrhunderts", Leipzig 1938 Mortensen, Hans und Gertrud: Kants väterliche Ahnen und ihre Umwelt, Rede von 1952 in Jahrbuch der Albertus-Universität zu Königsberg / Pr.
Holzner- Verlag Kitzingen/ Main 1953 Bd. 3 Peteraitis, Vilius: Mažoji Lietuva ir Tvanksta Vilnius 1992 Pietsch, Richard: Bildkarte rund um das Kurische Haff, Heimat-Buchdienst Georg Banszerus, Höxter, Herstellung: Neue Stalling, Oldenburg Pietsch, Richard: Deutsch-Kurisches Wörterbuch, Verlag Nordostdeutsches Kulturwerk Lüneburg 1991, ISBN 3-922296-60-2 Pietsch, Richard: Fischerleben auf der Kurischen Nehrung dargestellt in kurischer und deutscher Sprache, Verlag Ulrich Camen Berlin 1982 Schmid, Wolfgang P.: Nehrungskurisch, Sprachhistorische und instrumentalphonetische Studien zu einem aussterbenden Dialekt, Stuttgart 1989 Schmid, Wolfgang P.: Das Nehrungskurische, ein sprachhistorischer Überblick Tolksdorf, Ulrich "Fischerei und Fischerkultur in Ostpreußen", Heide/ Holstein 1991 Žadeikiene, Krajinskas, Albertas: Kurenkahnwimpel, ISBN 9986-830-63-X Pietsch-Bildkarte „Kurisches Haff“ https://web.archive.org/web/20090508152040/http://www.memelland-adm.de/kurenwimpel.html Curonians in Memelland Curonian placenames in Memelland Studentu zinātniskās konferences "Aktuāli baltistikas jautājumi" tēzes Loreta Stonkutė.
Kuršininkų tarmės lituanizmai. P.43,44