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Leo Ubbelohde
Leo Ubbelohde (4 January 1877, Hanover – 28 February 1964, Düsseldorf) was a German chemist. During his career he served as a professor in Karlsruhe and Berlin. He is known for his research on mineral oils, fuels, catalysis and viscosity. He was the inventor of a suspended-level viscometer used for determining kinetic viscosity, known today as a "Ubbelohde viscometer An Ubbelohde type viscometer or suspended-level viscometer is a measuring instrument which uses a capillary based method of measuring viscosity. It is recommended for higher viscosity cellulosic polymer solutions. The advantage of this instrumen ...". Publications * ''Über Kondensationen der Isatinsäure und des o-Amidobenzaldehyds mit Isonitrosoaceton'', (1903) * ''Handbuch der Chemie und Technologie der Öle und Fette : Chemie, Analyse, Gewinnung und Verarbeitung der Öle, Fette, Wachse und Harze''. * ''Zur Viskosimetrie. Anhang : Umwandlungs-tabellen für Viskositätszahlen'', (1940). [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hanover
Hanover (; german: Hannover ; nds, Hannober) is the capital and largest city of the German state of Lower Saxony. Its 535,932 (2021) inhabitants make it the 13th-largest city in Germany as well as the fourth-largest city in Northern Germany after Berlin, Hamburg and Bremen. Hanover's urban area comprises the towns of Garbsen, Langenhagen and Laatzen and has a population of about 791,000 (2018). The Hanover Region has approximately 1.16 million inhabitants (2019). The city lies at the confluence of the River Leine and its tributary the Ihme, in the south of the North German Plain, and is the largest city in the Hannover–Braunschweig–Göttingen–Wolfsburg Metropolitan Region. It is the fifth-largest city in the Low German dialect area after Hamburg, Dortmund, Essen and Bremen. Before it became the capital of Lower Saxony in 1946, Hannover was the capital of the Principality of Calenberg (1636–1692), the Electorate of Hanover (1692–1814), the Kingdom of H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Düsseldorf
Düsseldorf ( , , ; often in English sources; Low Franconian and Ripuarian: ''Düsseldörp'' ; archaic nl, Dusseldorp ) is the capital city of North Rhine-Westphalia, the most populous state of Germany. It is the second-largest city in the state and the seventh-largest city in Germany, with a population of 617,280. Düsseldorf is located at the confluence of two rivers: the Rhine and the Düssel, a small tributary. The ''-dorf'' suffix means "village" in German (English cognate: '' thorp''); its use is unusual for a settlement as large as Düsseldorf. Most of the city lies on the right bank of the Rhine. Düsseldorf lies in the centre of both the Rhine-Ruhr and the Rhineland Metropolitan Region. It neighbours the Cologne Bonn Region to the south and the Ruhr to the north. It is the largest city in the German Low Franconian dialect area (closely related to Dutch). Mercer's 2012 Quality of Living survey ranked Düsseldorf the sixth most livable city in the world. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms. Chemists carefully measure substance proportions, chemical reaction rates, and other chemical properties. In Commonwealth English, pharmacists are often called chemists. Chemists use their knowledge to learn the composition and properties of unfamiliar substances, as well as to reproduce and synthesize large quantities of useful naturally occurring substances and create new artificial substances and useful processes. Chemists may specialize in any number of subdisciplines of chemistry. Materials scientists and metallurgists share much of the same education and skills with chemists. The work of chemists is often related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karlsruhe
Karlsruhe ( , , ; South Franconian German, South Franconian: ''Kallsruh'') is the List of cities in Baden-Württemberg by population, third-largest city of the German States of Germany, state (''Land'') of Baden-Württemberg after its capital of Stuttgart and Mannheim, and the List of cities in Germany by population, 22nd-largest city in the nation, with 308,436 inhabitants. It is also a former capital of Baden, a historic region named after Hohenbaden Castle in the city of Baden-Baden. Located on the right bank of the Rhine near the French border, between the Mannheim/Ludwigshafen conurbation to the north and Strasbourg/Kehl to the south, Karlsruhe is Germany's legal center, being home to the Federal Constitutional Court (''Bundesverfassungsgericht''), the Federal Court of Justice (''Bundesgerichtshof'') and the Public Prosecutor General (Germany), Public Prosecutor General of the Federal Court of Justice (''Generalbundesanwalt beim Bundesgerichtshof''). Karlsruhe was the capit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berlin
Berlin is Capital of Germany, the capital and largest city of Germany, both by area and List of cities in Germany by population, by population. Its more than 3.85 million inhabitants make it the European Union's List of cities in the European Union by population within city limits, most populous city, as measured by population within city limits having gained this status after the United Kingdom's, and thus London's, Brexit, departure from the European Union. Simultaneously, the city is one of the states of Germany, and is the List of German states by area, third smallest state in the country in terms of area. Berlin is surrounded by the state of Brandenburg, and Brandenburg's capital Potsdam is nearby. The urban area of Berlin has a population of over 4.5 million and is therefore the most populous urban area in Germany. The Berlin/Brandenburg Metropolitan Region, Berlin-Brandenburg capital region has around 6.2 million inhabitants and is Germany's second-largest metropolitan reg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mineral Oil
Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, having been used for many specific oils over the past few centuries. Other names, similarly imprecise, include 'white oil', 'paraffin oil', ' liquid paraffin' (a highly refined medical grade), (Latin), and 'liquid petroleum'. Most often, mineral oil is a liquid by-product of refining crude oil to make gasoline and other petroleum products. This type of mineral oil is a transparent, colorless oil, composed mainly of alkanes and cycloalkanes, related to petroleum jelly. It has a density of around . Nomenclature Some of the imprecision in the definition of the names used for mineral oil (such as 'white oil') reflects usage by consumers and merchants who did not know, and usually had no need of knowing, the oil's precise chemical makeu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalysis
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant, or heterogeneous, whose components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Catalysis is ubiquitous in chemical industry of all kinds. Estimates are that 90% of all commercially produced chemical products involve catalysts at some st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the internal frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's axis than near its walls. Experiments show that some stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube with a constant rate of flow, the strength of the compensating force is proportional to the fluid's viscosity. In general, viscosity depends on a fluid's state, such as its temperature, pressure, and rate of deformation. However, the dependence on some of these properties ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscometer
A viscometer (also called viscosimeter) is an instrument used to measure the viscosity of a fluid. For liquids with viscosities which vary with flow conditions, an instrument called a rheometer is used. Thus, a rheometer can be considered as a special type of viscometer. Viscometers only measure under one flow condition. In general, either the fluid remains stationary and an object moves through it, or the object is stationary and the fluid moves past it. The drag caused by relative motion of the fluid and a surface is a measure of the viscosity. The flow conditions must have a sufficiently small value of Reynolds number for there to be laminar flow. At 20°C, the dynamic viscosity (kinematic viscosity × density) of water is 1.0038 mPa·s and its kinematic viscosity (product of flow time × factor) is 1.0022mm2/s. These values are used for calibrating certain types of viscometers. Standard laboratory viscometers for liquids U-tube viscometers These devices are also known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ubbelohde Viscometer
An Ubbelohde type viscometer or suspended-level viscometer is a measuring instrument which uses a capillary based method of measuring viscosity. It is recommended for higher viscosity cellulosic polymer solutions. The advantage of this instrument is that the values obtained are independent of the total volume. The device was developed by the German chemist Leo Ubbelohde (1877-1964). ASTM and other test methods are: ISO 3104, ISO 3105, ASTM D445, ASTM D446, ASTM D4020, IP 71, BS 188. The Ubbelohde viscometer is closely related to the Ostwald viscometer. Both are u-shaped pieces of glassware with a reservoir on one side and a measuring bulb with a capillary on the other. A liquid is introduced into the reservoir then sucked through the capillary and measuring bulb. The liquid is allowed to travel back through the measuring bulb and the time it takes for the liquid to pass through two calibrated marks is a measure for viscosity. The Ubbelohde device has a third arm extending fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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