Prague vs Cobalt

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Prague (; Czech: Praha [ˈpraɦa] (listen), German: Prag, Latin: Praga, Hebrew: פראג Prag‎) is the capital and largest city in the Czech Republic, the 13th largest city in the European Union and the historical capital of Bohemia. Situated on the Vltava river, Prague is home to about 1.3 million people, while its metropolitan area is estimated to have a population of 2.7 million. The city has a temperate oceanic climate, with relatively warm summers and chilly winters. Prague is a political, cultural and economic centre of central Europe complete with a rich history. Founded during the Romanesque and flourishing by the Gothic, Renaissance and Baroque eras, Prague was the capital of the Kingdom of Bohemia and the main residence of several Holy Roman Emperors, most notably of Charles IV (r. 1346–1378). It was an important city to the Habsburg Monarchy and its Austro-Hungarian Empire. The city played major roles in the Bohemian and Protestant Reformation, the Thirty Years' War and in 20th-century history as the capital of Czechoslovakia between the World Wars and the post-war Communist era.Prague is home to a number of well-known cultural attractions, many of which survived the violence and destruction of 20th-century Europe.

Main attractions include Prague Castle, Charles Bridge, Old Town Square with the Prague astronomical clock, the Jewish Quarter, Petřín hill and Vyšehrad. Since 1992, the extensive historic centre of Prague has been included in the UNESCO list of World Heritage Sites. The city has more than ten major museums, along with numerous theatres, galleries, cinemas and other historical exhibits. An extensive modern public transportation system connects the city. It is home to a wide range of public and private schools, including Charles University in Prague, the oldest university in Central Europe.Prague is classified as an "Alpha-" global city according to GaWC studies and ranked sixth in the Tripadvisor world list of best destinations in 2016. In 2019, the city was ranked as 69th most liveable city in the world by Mercer. In the same year, the PICSA Index ranked the city as 13th most liveable city in the world. Its rich history makes it a popular tourist destination and as of 2017, the city receives more than 8.5 million international visitors annually. In 2017 Prague was listed as the fifth most visited European city after London, Paris, Rome and Istanbul.

Source: Wikipedia

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Cobalt is a chemical element with the symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth's crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. Cobalt-based blue pigments (cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was later thought to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment-producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold. Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as cobaltite (CoAsS). The element is, however, more usually produced as a by-product of copper and nickel mining.

The copper belt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. World production in 2016 was 116,000 metric tons (114,000 long tons; 128,000 short tons) (according to Natural Resources Canada), and the DRC alone accounted for more than 50%.Cobalt is primarily used in lithium-ion batteries, and in the manufacture of magnetic, wear-resistant and high-strength alloys. The compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes. Cobalt occurs naturally as only one stable isotope, cobalt-59. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays. Cobalt is the active center of a group of coenzymes called cobalamins. Vitamin B12, the best-known example of the type, is an essential vitamin for all animals. Cobalt in inorganic form is also a micronutrient for bacteria, algae, and fungi.

Source: Wikipedia