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Brazilian Submarine Álvaro Alberto
''Álvaro Alberto'' the Brazil's first nuclear-powered attack submarine, is part of a strategic partnership signed between France and Brazil on 23 December 2008 by then-presidents Luiz Inácio Lula da Silva and Nicolas Sarkozy, that created the Submarine Development Program, a naval modernization plan of the Brazilian Armed Forces. The boat is the fifth unit of the ''Riachuelo''-class, based on the French ''Scorpène''-class. The submarine is being constructed by the Brazilian state-owned naval company ICN. Once ''Álvaro Alberto'' is completed, Brazil will be the seventh country in the world to field nuclear submarines. Brazil might be the first new operator of the ship type since 1987, when India commissioned the former Soviet Navy Charlie-class submarine INS ''Chakra''. ''Álvaro Alberto'' was named after the former Brazilian Navy vice admiral and scientist Álvaro Alberto da Motta e Silva, who was the responsible for the implementation of the country's nuclear program. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SN10 Alvaro Alberto
The SN1 reaction is a substitution reaction in organic chemistry, the name of which refers to the Hughes-Ingold symbol of the mechanism. "SN" stands for "nucleophilic substitution", and the "1" says that the rate-determining step is unimolecular. Thus, the rate equation is often shown as having first-order dependence on the substrate and zero-order dependence on the nucleophile. This relationship holds for situations where the amount of nucleophile is much greater than that of the intermediate. Instead, the rate equation may be more accurately described using steady-state kinetics. The reaction involves a carbocation intermediate and is commonly seen in reactions of secondary or tertiary alkyl halides under strongly basic conditions or, under strongly acidic conditions, with secondary or tertiary alcohols. With primary and secondary alkyl halides, the alternative SN2 reaction occurs. In inorganic chemistry, the SN1 reaction is often known as the ''dissociative substitution''. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scorpène-class Submarine
The Scorpène-class submarines are a class of diesel-electric attack submarines jointly developed by the French Naval Group (formerly the DCNS) and the Spanish company Navantia. It features diesel propulsion and an additional air-independent propulsion (AIP). It is now marketed as the Scorpène 2000. Scorpène characteristics The Scorpène class of submarines has three subtypes: the CM-2000 conventional diesel-electric version, the AM-2000 air-independent propulsion (AIP) derivative, the downsized CA-2000 coastal submarine, and the enlarged S-BR for the Brazilian Navy, without AIP. The Chilean and Malaysian boats are fitted with the TSM 2233 Mk 2 sonar. The class can also be fitted with a 'S-Cube' sonar suite from Thales. Air-independent propulsion The French Module d'Energie Sous-Marine Autonome (MESMA) system is being offered by the French shipyard Naval Group for the Scorpène-class submarines. It is essentially a modified version of their nuclear propulsion system with h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Uranium
Uranium (92U) is a naturally occurring radioactive element that has no stable isotope. It has two primordial isotopes, uranium-238 and uranium-235, that have long half-lives and are found in appreciable quantity in the Earth's crust. The decay product uranium-234 is also found. Other isotopes such as uranium-233 have been produced in breeder reactors. In addition to isotopes found in nature or nuclear reactors, many isotopes with far shorter half-lives have been produced, ranging from 214U to 242U (with the exceptions of 220U and 241U). The standard atomic weight of natural uranium is . Naturally occurring uranium is composed of three major isotopes, uranium-238 (99.2739–99.2752% natural abundance), uranium-235 (0.7198–0.7202%), and uranium-234 (0.0050–0.0059%). All three isotopes are radioactive (i.e., they are radioisotopes), and the most abundant and stable is uranium-238, with a half-life of (close to the age of the Earth). Uranium-238 is an alpha emitter, decayi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minas Gerais
Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally "Beautiful Horizon"), is a major urban and finance center in Latin America, and the sixth largest municipality in Brazil, after the cities of São Paulo, Rio de Janeiro, Salvador, Brasília and Fortaleza, but its metropolitan area is the third largest in Brazil with just over 5.8 million inhabitants, after those of São Paulo and Rio de Janeiro. Nine Brazilian presidents were born in Minas Gerais, the most of any state. The state has 10.1% of the Brazilian population and is responsible for 8.7% of the Brazilian GDP. With an area of —larger than Metropolitan France—it is the fourth most extensive state in Brazil. The main producer of coffee and milk in the country, Minas Gerais is known for its heritage of architecture and colonia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poços De Caldas
Poços de Caldas is a municipality in the south of Minas Gerais state, Brazil, in the microregion of the same name. Its estimated population in 2020 was 168,641 inhabitants. The city is known for its hot springs. History Poços was founded in 1872. The region had been inhabited by the Cataguases Indians, who were expelled from their lands by the '' Bandeiras Unidas Paulistas'' during their quest for gold. The place was first called ''Freguesia de Nossa Senhora da Saúde das Águas de Caldas'' ("Parish of Our Lady of Health of Caldas Waters"). In 1874 it became a district, then, in 1875, it was elevated to the category of city. It became famous after the discovery of the hot springs, and many important people began to visit the spa in search of cures provided by the water. The name comes from Caldas da Rainha, a spa town in central Portugal. Geography It lies on the boundary of the state of São Paulo at 1186 meters elevation and is the main socio-economic nucleus of its regi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium Hexafluoride
Uranium hexafluoride (), (sometimes called "hex") is an inorganic compound with the formula UF6. Uranium hexafluoride is a volatile white solid that reacts with water, releasing corrosive hydrofluoric acid. The compound reacts mildly with aluminium, forming a thin surface layer of AlF3 that resists any further reaction from the compound. UF6 is used in the process of enriching uranium, which produces fuel for nuclear reactors and nuclear weapons. Preparation Milled uranium ore—U3O8 or "yellowcake"—is dissolved in nitric acid, yielding a solution of uranyl nitrate UO2(NO3)2. Pure uranyl nitrate is obtained by solvent extraction, then treated with ammonia to produce ammonium diuranate ("ADU", (NH4)2U2O7). Reduction with hydrogen gives UO2, which is converted with hydrofluoric acid (HF) to uranium tetrafluoride, UF4. Oxidation with fluorine yields UF6. During nuclear reprocessing, uranium is reacted with chlorine trifluoride to give UF6: :U + 2 ClF3 → UF6 + Cl2 Prope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
João Figueiredo
João Baptista de Oliveira Figueiredo (; 15 January 1918 – 24 December 1999) was a Brazilian military leader and politician who was the 30th president of Brazil from 1979 to 1985, the last of the military regime that ruled the country following the 1964 Brazilian countercoup d'état. He was chief of the Secret Service (SNI) during the term of his predecessor, Ernesto Geisel, who appointed him to the presidency at the end of his own mandate. He continued the process of redemocratization that Geisel had started and sanctioned a law decreeing amnesty for all political crimes committed during the regime. His term was marked by a severe economic crisis and growing dissatisfaction with the military rule, culminating in the Diretas Já protests of 1984, which clamored for direct elections for the Presidency, the last of which had taken place 24 years prior. Figueiredo opposed this and in 1984 Congress rejected the immediate return of direct elections, in favor of an indirect elec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernesto Geisel
Ernesto Beckmann Geisel (, ; 3 August 1907 – 12 September 1996) was a Brazilian Army officer and politician, who was List of Presidents of Brazil, President of Brazil from 1974 to 1979, during the Brazilian military regime. Early life and family Ernesto Geisel was born in Bento Gonçalves, Rio Grande do Sul, Bento Gonçalves, Rio Grande do Sul province. His father was Guilherme Augusto Geisel (born Wilhelm August Geisel), a German Brazilian teacher from Herborn (Hesse), Herborn who immigrated to the Empire of Brazil in 1883 at age 16. His mother was the homemaker Lydia Beckmann, born in Brazil in Teutônia colony to German parents from Osnabrück. In Bento Gonçalves, Rio Grande do Sul, Bento Gonçalves, where Ernesto was raised, there were only two families of German origin (Geisels and Drehers), and most of the population was composed of Italian Brazilian, Italian immigrants. Remembering the contact with the local Italian immigrants during his childhood Geisel described the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Military Dictatorship In Brazil
The military dictatorship in Brazil ( pt, ditadura militar) was established on 1 April 1964, after a coup d'état by the Brazilian Armed Forces, with support from the United States government, against President João Goulart. The Brazilian dictatorship lasted for 21 years, until 15 March 1985. The military coup was fomented by José de Magalhães Pinto, Adhemar de Barros, and Carlos Lacerda (who had already participated in the conspiracy to depose Getúlio Vargas in 1945), then governors of the states of Minas Gerais, São Paulo, and Guanabara, respectively. The coup was planned and executed by the most forefront commanders of the Brazilian Army and received the support of almost all high-ranking members of the military, along with conservative elements in society, like the Catholic Church and anti-communist civil movements among the Brazilian middle and upper classes. Internationally, it was supported by the State Department of the United States through its embassy in Brasil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fuel Cycle
The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the ''front end'', which are the preparation of the fuel, steps in the ''service period'' in which the fuel is used during reactor operation, and steps in the ''back end'', which are necessary to safely manage, contain, and either reprocess or dispose of spent nuclear fuel. If spent fuel is not reprocessed, the fuel cycle is referred to as an ''open fuel cycle'' (or a ''once-through fuel cycle''); if the spent fuel is reprocessed, it is referred to as a ''closed fuel cycle''. Basic concepts Nuclear power relies on fissionable material that can sustain a chain reaction with neutrons. Examples of such materials include uranium and plutonium. Most nuclear reactors use a moderator to lower the kinetic energy of the neutrons and increase the probability that fission will occur. This allows reactors to use material with far lower con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brazilian Academy Of Sciences
The Brazilian Academy of Sciences ( pt, italic=yes, Academia Brasileira de Ciências or ''ABC'') is the national academy of Brazil. It is headquartered in the city of Rio de Janeiro and was founded on May 3, 1916. Publications It publishes a large number of scientific publications, among them the ''Anais da Academia Brasileira de Ciências'' (2020 impact factor, IF 1.280). People Presidents * 1916–1926 Henrique Charles Morize * 1926–1929 Juliano Moreira * 1929–1931 Miguel Osório de Almeida * 1931–1933 Eusébio Paulo de Oliveira * 1933–1935 Arthur Alexandre Moses * 1935–1937 Álvaro Alberto da Mota e Silva * 1937–1939 Adalberto Menezes de Oliveira * 1939–1941 Inácio Manuel Azevedo do Amaral * 1941–1943 Arthur Alexandre Moses * 1943–1945 Cândido Firmino de Melo Leitão * 1945–1947 Mario Paulo de Brito * 1947–1949 Arthur Alexandre Moses * 1949–1951 Álvaro Alberto da Mota e Silva * 1951–1965 Arthur Alexandre Moses * 1965–1967 Carlos Chagas Filho * 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United Nations Atomic Energy Commission
The United Nations Atomic Energy Commission (UNAEC) was founded on 24 January 1946 by the very first resolution of the United Nations General Assembly "to deal with the problems raised by the discovery of atomic energy." The General Assembly asked the Commission to "make specific proposals: (a) for extending between all nations the exchange of basic scientific information for peaceful ends; (b) for control of atomic energy to the extent necessary to ensure its use only for peaceful purposes; (c) for the elimination from national armaments of atomic weapons and of all other major weapons adaptable to mass destruction; (d) for effective safeguards by way of inspection and other means to protect complying States against the hazards of violations and evasions." On 14 December 1946, the General Assembly passed a follow-up resolution urging an expeditious completion of the report by the Commission as well as its consideration by the United Nations Security Council. The Security Council r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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