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106-525: Defined by physical geography , Southern Africa is home to a number of river systems; the Zambezi River is the most prominent. The Zambezi flows from the northwest corner of Zambia and western Angola to the Indian Ocean on the coast of Mozambique . Along the way, it flows over Victoria Falls on the border between Zambia and Zimbabwe . Victoria Falls is one of the largest waterfalls in

212-514: A "principle of comprehensive analysis of the territory" and "Russian Chernozem ". In the latter, he introduced the geographical concept of soil, as distinct from a simple geological stratum, and thus found a new geographic area of study: pedology . Climatology also received a strong boost from the Russian school by Wladimir Köppen whose main contribution, climate classification, is still valid today. However, this great geographer also contributed to

318-631: A batch reactor with an inert atmosphere at a temperature of 1,000 °C. Dilute hydrochloric acid is then used to leach the salt from the product. The processing of titanium metal occurs in four major steps: reduction of titanium ore into "sponge", a porous form; melting of sponge, or sponge plus a master alloy to form an ingot; primary fabrication, where an ingot is converted into general mill products such as billet , bar, plate , sheet , strip, and tube ; and secondary fabrication of finished shapes from mill products. Because it cannot be readily produced by reduction of titanium dioxide, titanium metal

424-464: A carbon monoxide atmosphere with chlorine gas before reducing it to titanium metal by the use of sodium. Pure metallic titanium (99.9%) was first prepared in 1910 by Matthew A. Hunter at Rensselaer Polytechnic Institute by heating TiCl 4 with sodium at 700–800 °C (1,292–1,472 °F) under great pressure in a batch process known as the Hunter process . Titanium metal was not used outside

530-624: A component of smoke screens and catalysts ; and titanium trichloride (TiCl 3 ), which is used as a catalyst in the production of polypropylene . Titanium can be alloyed with iron , aluminium , vanadium , and molybdenum , among other elements. The resulting titanium alloys are strong, lightweight, and versatile, with applications including aerospace ( jet engines , missiles , and spacecraft ), military, industrial processes (chemicals and petrochemicals, desalination plants , pulp , and paper ), automotive, agriculture (farming), sporting goods, jewelry, and consumer electronics . Titanium

636-687: A couple of dozen are readily available commercially. The ASTM International recognizes 31 grades of titanium metal and alloys, of which grades one through four are commercially pure (unalloyed). Those four vary in tensile strength as a function of oxygen content, with grade 1 being the most ductile (lowest tensile strength with an oxygen content of 0.18%), and grade 4 the least ductile (highest tensile strength with an oxygen content of 0.40%). The remaining grades are alloys, each designed for specific properties of ductility, strength, hardness, electrical resistivity, creep resistance, specific corrosion resistance, and combinations thereof. In addition to

742-622: A lustrous transition metal with a silver color , low density , and high strength, resistant to corrosion in sea water , aqua regia , and chlorine . Titanium was discovered in Cornwall , Great Britain , by William Gregor in 1791 and was named by Martin Heinrich Klaproth after the Titans of Greek mythology . The element occurs within a number of minerals , principally rutile and ilmenite , which are widely distributed in

848-406: A major development. Some of his disciples made significant contributions to various branches of physical geography such as Curtis Marbut and his invaluable legacy for Pedology, Mark Jefferson , Isaiah Bowman , among others. The compilation of Edrisi marks an era in the history of science . Not only is its historical information most interesting and valuable, but its descriptions of many parts of

954-631: A merging of populations in East and South Africa . Homo naledi likely coexisted with modern humans in Africa about 300,000 years ago. The Kingdom of Mapungubwe (c. 1075–c. 1220) was one of the earliest state in the South African region. It was located at between the Shashe and Limpopo Rivers. The name is derived from either TjiKalanga and Tshivenda . The kingdom is thought to have existed as

1060-438: A mixture of oxides and deposits coatings with variable refractive index. Also known is Ti 2 O 3 , with the corundum structure, and TiO , with the rock salt structure , although often nonstoichiometric . The alkoxides of titanium(IV), prepared by treating TiCl 4 with alcohols , are colorless compounds that convert to the dioxide on reaction with water. They are industrially useful for depositing solid TiO 2 via

1166-434: A reducing agent in organic chemistry. Owing to the important role of titanium compounds as polymerization catalyst, compounds with Ti-C bonds have been intensively studied. The most common organotitanium complex is titanocene dichloride ((C 5 H 5 ) 2 TiCl 2 ). Related compounds include Tebbe's reagent and Petasis reagent . Titanium forms carbonyl complexes , e.g. (C 5 H 5 ) 2 Ti(CO) 2 . Following

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1272-401: A robust mining sector and comparatively developed secondary and tertiary sectors . Additionally many countries (with the exception of Mozambique and Malawi in particular) have relatively well developed infrastructure. Some of its main exports including platinum , diamonds , gold , copper , cobalt , chromium and uranium , Southern Africa still faces some of the problems that the rest of

1378-472: A sample of manaccanite and confirmed that it contained titanium. The currently known processes for extracting titanium from its various ores are laborious and costly; it is not possible to reduce the ore by heating with carbon (as in iron smelting) because titanium combines with the carbon to produce titanium carbide. An extraction of 95% pure titanium was achieved by Lars Fredrik Nilson and Otto Petterson . To achieve this they chlorinated titanium oxide in

1484-407: A small population of European ( Afrikaner , British , Portuguese Africans , etc.) and Asian descent ( Cape Malays , Indian South Africans , etc.) people in many southern African countries. Further information in the sections of Architecture of Africa : Further information in the sections of History of science and technology in Africa : Some key factors affecting the food security within

1590-725: A variety of conditions, such as embrittlement , which reduce the integrity of the assembly welds and lead to joint failure. Titanium is very difficult to solder directly, and hence a solderable metal or alloy such as steel is coated on titanium prior to soldering. Titanium metal can be machined with the same equipment and the same processes as stainless steel . Common titanium alloys are made by reduction. For example, cuprotitanium (rutile with copper added), ferrocarbon titanium (ilmenite reduced with coke in an electric furnace), and manganotitanium (rutile with manganese or manganese oxides) are reduced. About fifty grades of titanium alloys are designed and currently used, although only

1696-421: Is positron emission (with the exception of Ti which undergoes electron capture ), leading to isotopes of scandium , and the primary mode for isotopes heavier than Ti is beta emission , leading to isotopes of vanadium . Titanium becomes radioactive upon bombardment with deuterons , emitting mainly positrons and hard gamma rays . The +4 oxidation state dominates titanium chemistry, but compounds in

1802-472: Is 60% denser than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy . Certain titanium alloys (e.g., Beta C ) achieve tensile strengths of over 1,400 MPa (200,000 psi). However, titanium loses strength when heated above 430 °C (806 °F). Titanium is not as hard as some grades of heat-treated steel; it is non-magnetic and a poor conductor of heat and electricity. Machining requires precautions, because

1908-504: Is a major food producer and exporter in the region. Data on agricultural production trends and food insecurity especially in term of food availability for Southern Africa is readily available through the Famine Early Warning Systems Network ( FEWS NET ) and Southern African Development Community ( SADC ) - Food, Agriculture and Nature Resource Directorate (FARN). However, this data might not fully capture

2014-473: Is about 4 picomolar in the ocean. At 100 °C, the concentration of titanium in water is estimated to be less than 10 M at pH 7. The identity of titanium species in aqueous solution remains unknown because of its low solubility and the lack of sensitive spectroscopic methods, although only the 4+ oxidation state is stable in air. No evidence exists for a biological role, although rare organisms are known to accumulate high concentrations of titanium. Titanium

2120-548: Is also considered one of the most biocompatible metals, leading to a range of medical applications including prostheses , orthopedic implants , dental implants , and surgical instruments . The two most useful properties of the metal are corrosion resistance and strength-to-density ratio , the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels , but less dense. There are two allotropic forms and five naturally occurring isotopes of this element, Ti through Ti, with Ti being

2226-500: Is also very hard, is found in cutting tools and coatings. Titanium tetrachloride (titanium(IV) chloride, TiCl 4 ) is a colorless volatile liquid (commercial samples are yellowish) that, in air, hydrolyzes with spectacular emission of white clouds. Via the Kroll process , TiCl 4 is used in the conversion of titanium ores to titanium metal. Titanium tetrachloride is also used to make titanium dioxide, e.g., for use in white paint. It

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2332-854: Is an extremely rare mineral consisting of titanium dioxide. Of these minerals, only rutile and ilmenite have economic importance, yet even they are difficult to find in high concentrations. About 6.0 and 0.7 million tonnes of those minerals were mined in 2011, respectively. Significant titanium-bearing ilmenite deposits exist in Australia , Canada , China , India , Mozambique , New Zealand , Norway , Sierra Leone , South Africa , and Ukraine . About 210,000 tonnes of titanium metal sponge were produced in 2020, mostly in China (110,000 t), Japan (50,000 t), Russia (33,000 t) and Kazakhstan (15,000 t). Total reserves of anatase, ilmenite, and rutile are estimated to exceed 2 billion tonnes. The concentration of titanium

2438-468: Is another mountain lift and the cycle continues. Although Davis's theory is not entirely accurate, it was absolutely revolutionary and unique in its time and helped to modernize and create a geography subfield of geomorphology . Its implications prompted a myriad of research in various branches of physical geography. In the case of the Paleogeography, this theory provided a model for understanding

2544-637: Is contained in meteorites , and it has been detected in the Sun and in M-type stars (the coolest type) with a surface temperature of 3,200 °C (5,790 °F). Rocks brought back from the Moon during the Apollo 17 mission are composed of 12.1% TiO 2 . Native titanium (pure metallic) is very rare. Naturally occurring titanium is composed of five stable isotopes : Ti, Ti, Ti, Ti, and Ti, with Ti being

2650-489: Is corroded by concentrated acids. Titanium is a very reactive metal that burns in normal air at lower temperatures than the melting point. Melting is possible only in an inert atmosphere or vacuum. At 550 °C (1,022 °F), it combines with chlorine. It also reacts with the other halogens and absorbs hydrogen. Titanium readily reacts with oxygen at 1,200 °C (2,190 °F) in air, and at 610 °C (1,130 °F) in pure oxygen, forming titanium dioxide . Titanium

2756-406: Is heated to this transition temperature but then falls and remains fairly constant for the β form regardless of temperature. Like aluminium and magnesium , the surface of titanium metal and its alloys oxidize immediately upon exposure to air to form a thin non-porous passivation layer that protects the bulk metal from further oxidation or corrosion. When it first forms, this protective layer

2862-829: Is manufactured using a flow production process known as the Armstrong process that is similar to the batch production Hunter process . A stream of titanium tetrachloride gas is added to a stream of molten sodium; the products (sodium chloride salt and titanium particles) is filtered from the extra sodium. Titanium is then separated from the salt by water washing. Both sodium and chlorine are recycled to produce and process more titanium tetrachloride. Methods for electrolytic production of Ti metal from TiO 2 using molten salt electrolytes have been researched and tested at laboratory and small pilot plant scales. The lead author of an impartial review published in 2017 considered his own process "ready for scaling up." A 2023 review "discusses

2968-426: Is not the case. It is paramagnetic and has fairly low electrical and thermal conductivity compared to other metals. Titanium is superconducting when cooled below its critical temperature of 0.49 K. Commercially pure (99.2% pure) grades of titanium have ultimate tensile strength of about 434  MPa (63,000  psi ), equal to that of common, low-grade steel alloys, but are less dense. Titanium

3074-565: Is obtained by reduction of titanium tetrachloride (TiCl 4 ) with magnesium metal in the Kroll process. The complexity of this batch production in the Kroll process explains the relatively high market value of titanium, despite the Kroll process being less expensive than the Hunter process. To produce the TiCl 4 required by the Kroll process, the dioxide is subjected to carbothermic reduction in

3180-511: Is one of the few elements that burns in pure nitrogen gas, reacting at 800 °C (1,470 °F) to form titanium nitride , which causes embrittlement. Because of its high reactivity with oxygen, nitrogen, and many other gases, titanium that is evaporated from filaments is the basis for titanium sublimation pumps , in which titanium serves as a scavenger for these gases by chemically binding to them. Such pumps inexpensively produce extremely low pressures in ultra-high vacuum systems. Titanium

3286-469: Is only 1–2  nm thick but it continues to grow slowly, reaching a thickness of 25 nm in four years. This layer gives titanium excellent resistance to corrosion against oxidizing acids, but it will dissolve in dilute hydrofluoric acid , hot hydrochloric acid, and hot sulfuric acid. Titanium is capable of withstanding attack by dilute sulfuric and hydrochloric acids at room temperature, chloride solutions, and most organic acids. However, titanium

Southern Africa - Misplaced Pages Continue

3392-412: Is only limited data on the other Southern African countries. From 2018 to 2021, parts of the region suffered from a period of drought . Physical geography Physical geography (also known as physiography ) is one of the three main branches of geography . Physical geography is the branch of natural science which deals with the processes and patterns in the natural environment such as

3498-559: Is set apart from other Sub-Saharan African regions because of its mineral resources, including copper, diamonds, gold, zinc, chromium, platinum, manganese, iron ore, and coal. Countries in Southern Africa are larger in geographic area, except three smaller landlocked states: Lesotho, Swaziland, and Malawi. The larger states- South Africa, Botswana, Mozambique, Zimbabwe, Zambia, Namibia, and Angola—all have extensive mineral deposits. These widespread mineral resources make this one of

3604-483: Is surrounded by six oxide ligands that link to other Ti centers. The term titanates usually refers to titanium(IV) compounds, as represented by barium titanate (BaTiO 3 ). With a perovskite structure, this material exhibits piezoelectric properties and is used as a transducer in the interconversion of sound and electricity . Many minerals are titanates, such as ilmenite (FeTiO 3 ). Star sapphires and rubies get their asterism (star-forming shine) from

3710-569: Is the dominant economy of the region. Generally, mining, agriculture, the public sector and tourism dominate the economies of Southern African countries, apart from South Africa which has mature and flourishing financial, retail, and construction sectors. Zimbabwe maintains a smaller banking and real estate sector along with what remains of its manufacturing industry, despite a protracted economic crisis . Most global banks have their regional offices for Southern Africa based in Johannesburg . Over

3816-681: Is the ninth-most abundant element in Earth 's crust (0.63% by mass ) and the seventh-most abundant metal. It is present as oxides in most igneous rocks , in sediments derived from them, in living things, and natural bodies of water. Of the 801 types of igneous rocks analyzed by the United States Geological Survey , 784 contained titanium. Its proportion in soils is approximately 0.5–1.5%. Common titanium-containing minerals are anatase , brookite , ilmenite , perovskite , rutile , and titanite (sphene). Akaogiite

3922-471: Is used in steel as an alloying element ( ferro-titanium ) to reduce grain size and as a deoxidizer , and in stainless steel to reduce carbon content. Titanium is often alloyed with aluminium (to refine grain size), vanadium , copper (to harden), iron , manganese , molybdenum , and other metals. Titanium mill products (sheet, plate, bar, wire, forgings, castings) find application in industrial, aerospace, recreational, and emerging markets. Powdered titanium

4028-514: Is widely used in organic chemistry as a Lewis acid , for example in the Mukaiyama aldol condensation . In the van Arkel–de Boer process , titanium tetraiodide (TiI 4 ) is generated in the production of high purity titanium metal. Titanium(III) and titanium(II) also form stable chlorides. A notable example is titanium(III) chloride (TiCl 3 ), which is used as a catalyst for production of polyolefins (see Ziegler–Natta catalyst ) and

4134-601: The Bushveld basin into South Africa. This extends southwest through the Witwatersrand and Northern Cape of South Africa toward the southern coast. Mining activity exists across the eastern region. Diamond mining is found in parts of Botswana and along the Namibian coast. Coal can also be found in central Mozambique, Zimbabwe and northeast South Africa. The climate of the region is broadly divided into subtropical in

4240-716: The Defense National Stockpile Center , until the stockpile was dispersed in the 2000s. As of 2021, the four leading producers of titanium sponge were China (52%), Japan (24%), Russia (16%) and Kazakhstan (7%). The Hunter process was the first industrial process to produce pure metallic titanium. It was invented in 1910 by Matthew A. Hunter , a chemist born in New Zealand who worked in the United States. The process involves reducing titanium tetrachloride (TiCl 4 ) with sodium (Na) in

4346-409: The Earth's crust and lithosphere ; it is found in almost all living things, as well as bodies of water, rocks, and soils. The metal is extracted from its principal mineral ores by the Kroll and Hunter processes. The most common compound, titanium dioxide , is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl 4 ),

Southern Africa - Misplaced Pages Continue

4452-736: The Southern African Bird Atlas Project , and Mammals of the Southern African Subregion . It is not used in political, economic, or human geography contexts because the definition cuts Mozambique in two. In the United Nations geoscheme for Africa, five states constitute Southern Africa: This definition excludes other countries in the region, and instead includes the Comoros, Madagascar, Malawi, Mauritius, Mayotte, Mozambique, Réunion,

4558-572: The atmosphere , hydrosphere , biosphere , and geosphere . This focus is in contrast with the branch of human geography , which focuses on the built environment , and technical geography , which focuses on using, studying, and creating tools to obtain, analyze, interpret, and understand spatial information. The three branches have significant overlap, however. Physical geography can be divided into several branches or related fields, as follows: Main category: Geography Journals Mental geography and earth science journals communicate and document

4664-525: The colonial territories led to the independence of new states of Angola and Mozambique as well as Southern Rhodesia , which declared independence as Zimbabwe in 1980. The denouement of South West Africa achieved independence as Namibia in 1990 and the black majority in South Africa took power after the democratic elections in 1994 , therefore ending the Apartheid regime. From the end of

4770-572: The electrochemical principles involved in the recovery of metals from aqueous solutions and fused salt electrolytes", with particular attention paid to titanium. While some metals such as nickel and copper can be refined by electrowinning at room temperature, titanium must be in the molten state and "there is a strong chance of attack of the refractory lining by molten titanium." Zhang et al concluded their Perspective on Thermochemical and Electrochemical Processes for Titanium Metal Production in 2017 that "Even though there are strong interests in

4876-484: The sol-gel process . Titanium isopropoxide is used in the synthesis of chiral organic compounds via the Sharpless epoxidation . Titanium forms a variety of sulfides, but only TiS 2 has attracted significant interest. It adopts a layered structure and was used as a cathode in the development of lithium batteries . Because Ti(IV) is a "hard cation" , the sulfides of titanium are unstable and tend to hydrolyze to

4982-540: The +3 oxidation state are also numerous. Commonly, titanium adopts an octahedral coordination geometry in its complexes, but tetrahedral TiCl 4 is a notable exception. Because of its high oxidation state, titanium(IV) compounds exhibit a high degree of covalent bonding . The most important oxide is TiO 2 , which exists in three important polymorphs ; anatase, brookite, and rutile. All three are white diamagnetic solids, although mineral samples can appear dark (see rutile ). They adopt polymeric structures in which Ti

5088-669: The 1820s between Shaka's half-brothers Dingane and Mhlangana due to a succession dispute. Boer settlers began arriving northwards of the Orange River in the 1830s, which led to conflicts between the two peoples and resulted in the Battle of Blood River in 1838. The kingdom fell during the Anglo-Zulu War of the late 19th-century. In the aftermath of World War II , the colonial powers came under international pressure to decolonize. The transfer to an African majority, however,

5194-451: The 1990s these industries have struggled in the face of globalization and cheaper imports from China , leading to job losses particularly in heavy industry , gold mining and textiles . Zimbabwe in particular has seen significant deindustrialization as a result of factors both domestic and foreign. While colonialism has left its mark on the development over the course of history, today poverty , corruption , and HIV / AIDS are some of

5300-464: The ASTM specifications, titanium alloys are also produced to meet aerospace and military specifications (SAE-AMS, MIL-T), ISO standards, and country-specific specifications, as well as proprietary end-user specifications for aerospace, military, medical, and industrial applications. Commercially pure flat product (sheet, plate) can be formed readily, but processing must take into account of the tendency of

5406-727: The Ancient Age. In more modern times, these works include the Alexander von Humboldt ( Kosmos ) in the nineteenth century, in which geography is regarded as a physical and natural science through the work Summa de Geografía of Martín Fernández de Enciso from the early sixteenth century, which indicated for the first time the New World. During the eighteenth and nineteenth centuries, a controversy exported from geology, between supporters of James Hutton (uniformitarianism thesis) and Georges Cuvier (catastrophism) strongly influenced

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5512-807: The June–August rainfall maximum in the western cape. Year-to-year variability in rainfall, including drought, is associated with changes in global and regional sea surface temperatures . These include the El Nino Southern Oscillation , the Subtropical Indian Ocean Dipole , and changes in the Benguela Current region in the southeast Atlantic. Future climate projections suggest that much of southern Africa will get hotter and drier in response to global climate change. East and southern Africa are among

5618-520: The SADC members. The terrain of Southern Africa is varied, ranging from forest and grasslands to deserts . The region has both low-lying coastal areas, and mountains. In terms of natural resources, the region has the world's largest resources of platinum and the platinum group elements, chromium , vanadium , and cobalt , as well as uranium , gold , copper , titanium , iron , manganese , silver , beryllium , and diamonds . Southern Africa

5724-766: The SADC region and ensures sustainable energy developments through sound economic, environmental and social practices. The main objective of the power pool is to develop a world class, robust and safe interconnected electrical system across the Southern African Region. According to a report by Southern Africa Power Pool, the three largest producers of electricity in Southern Africa as at 2017, include Eskom in South Africa with an estimated 46,963MW, Zesco in Zambia with 2,877MW and SNL of Angola with 2,442MW. Whilst moderately successful by African standards,

5830-930: The Scattered Islands in the Indian Ocean (as a part of the French Southern Territories ), Zambia, and Zimbabwe in Eastern Africa , Angola in Middle Africa (or Central Africa), and Saint Helena, Ascension, and Tristan da Cunha (under the name Saint Helena) in Western Africa , instead. Some atlases include Malawi, Zambia, and Zimbabwe in Central Africa instead of Southern or Eastern Africa. The Southern African Customs Union , created in 1969, also comprises

5936-713: The South African border. There are numerous environmental issues in Southern Africa , including air pollution and desertification . Southern Africa is home to many people. It was initially populated by San , Hottentots and Pygmies in widely dispersed concentrations. Due to the Bantu expansion , the majority of African ethnic groups in this region, including the Xhosa , Zulu , Tsonga , Swazi , Northern Ndebele , Southern Ndebele , Tswana , Sotho , Pedi , Mbundu , Ovimbundu , Shona , Chaga and Sukuma , speak Bantu languages . The process of colonization and settling resulted in

6042-596: The Western Cape in South Africa, the major rainfall season is during the southern-hemisphere summer, from December to February. In the Western Cape , the rainfall maximum occurs from June through August. There are a number of important rainfall-producing weather systems in southern Africa. These include tropical-extra-tropical cloud bands, tropical lows, and tropical cyclones , cut-off lows , and mesoscale convective systems . Winter midlatitude storms account for

6148-519: The Zambezi and Limpopo river valleys, probably due to the lower altitude. The Western Cape has a Mediterranean vegetation and climate, including the unique fynbos , grading eastward into an oceanic climate along the Garden Route to Gqeberha and East London . The Namib and Kalahari deserts form arid lands in the centre-west, separating the highlands, woodlands, croplands, and pastures of

6254-491: The biggest factors impeding economic growth. In addition, South Africa and Zimbabwe in particular, face high emigration among their skilled workers leading to a significant brain drain to western economies and billions lost in human capital flight . The pursuit of economic and political stability is an important part of the region's goals, as demonstrated by the SADC, however complete regional integration remains an elusive target. In terms of economic strength, South Africa

6360-553: The birth of geography as a science during the Greek classical period and until the late nineteenth century with the birth of anthropogeography (human geography), geography was almost exclusively a natural science: the study of location and descriptive gazetteer of all places of the known world. Several works among the best known during this long period could be cited as an example, from Strabo ( Geography ), Eratosthenes ( Geographika ) or Dionysius Periegetes ( Periegesis Oiceumene ) in

6466-443: The continent does. Despite this, diamond production has fueled the economies of Botswana and Namibia, for example. Over the 20th century, the region developed a robust manufacturing sector, focused on South Africa and Zimbabwe, which allowed greater prosperity and investments into infrastructure, education and healthcare that elevated both nations into middle income economies and captured growing markets across Africa. However, since

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6572-416: The creation of potentially effective, selective, and stable titanium-based drugs. Titanium was discovered in 1791 by the clergyman and geologist William Gregor as an inclusion of a mineral in Cornwall , Great Britain. Gregor recognized the presence of a new element in ilmenite when he found black sand by a stream and noticed the sand was attracted by a magnet . Analyzing the sand, he determined

6678-414: The earliest regions where modern humans (Homo sapiens) and their predecessors are believed to have lived. In September 2019, scientists reported the computerized determination, based on 260 CT scans , of a virtual skull shape of the last common human ancestor to modern humans , representative of the earliest modern humans, and suggested that modern humans arose between 350,000 and 260,000 years ago through

6784-524: The early 1950s, titanium came into use extensively in military aviation, particularly in high-performance jets, starting with aircraft such as the F-100 Super Sabre and Lockheed A-12 and SR-71 . Throughout the Cold War period, titanium was considered a strategic material by the U.S. government, and a large stockpile of titanium sponge (a porous form of the pure metal) was maintained by

6890-546: The earth are still authoritative. For three centuries geographers copied his maps without alteration. The relative position of the lakes which form the Nile, as delineated in his work, does not differ greatly from that established by Baker and Stanley more than seven hundred years afterward, and their number is the same. Titanium Titanium is a chemical element ; it has symbol Ti and atomic number 22. Found in nature only as an oxide , it can be reduced to produce

6996-401: The evolution of the landscape. For hydrology, glaciology, and climatology as a boost investigated as studying geographic factors shape the landscape and affect the cycle. The bulk of the work of William Morris Davis led to the development of a new branch of physical geography: Geomorphology whose contents until then did not differ from the rest of geography. Shortly after this branch would present

7102-591: The expansion of supermarkets in the region, which is changing the way people obtain food in the city, rural-to-urban migration, unemployment, and poverty. The issue of food insecurity in general and urban food insecurity in particular in the region is also characterized by an increased consumption of caloric junk food and processed foods leading to potential increase in the co-existence of undernutrition and dietary-related chronic diseases such as obesity and hypertension. In South Africa for example, while over 50% experience hunger, 61% are overweight or morbidly obese. There

7208-617: The field of geography, because geography at this time was a natural science. Two historical events during the nineteenth century had a great effect on the further development of physical geography. The first was the European colonial expansion in Asia , Africa , Australia and even America in search of raw materials required by industries during the Industrial Revolution . This fostered the creation of geography departments in

7314-491: The field to develop cycle of erosion theory which he proposed as a paradigm for geography in general, although in actually served as a paradigm for physical geography. His theory explained that mountains and other landforms are shaped by factors that are manifested cyclically. He explained that the cycle begins with the lifting of the relief by geological processes (faults, volcanism, tectonic upheaval, etc.). Factors such as rivers and runoff begin to create V-shaped valleys between

7420-486: The first class-based social system within the region. Society was mainly centered around family and farming. The kingdom would culminate to the Kingdom of Zimbabwe in the 13th century. And at its height the capital's population was about 5000 people. There are no written records from the kingdom and what historians and archeologists know of the state is from the remains of buildings. The Kingdom of Zimbabwe (c. 1220–1450)

7526-794: The five states in the UN subregion of Southern Africa. The Southern African Development Community (SADC) was established in 1980 to facilitate co-operation in the region. It includes: Other than the UN subregion, these countries and territories are often included in Southern Africa: The Democratic Republic of the Congo is generally included in Central Africa, while Seychelles and Tanzania are more commonly associated with Eastern Africa, but these three countries have occasionally been included in Southern Africa, as they are

7632-558: The industry for finding a better method to produce Ti metal, and a large number of new concepts and improvements have been investigated at the laboratory or even at pilot plant scales, there is no new process to date that can replace the Kroll process commercially." The Hydrogen assisted magnesiothermic reduction (HAMR) process uses titanium dihydride . All welding of titanium must be done in an inert atmosphere of argon or helium to shield it from contamination with atmospheric gases (oxygen, nitrogen, and hydrogen). Contamination causes

7738-639: The island country of Madagascar is often not included due to its distinct language and cultural heritage. In physical geography , the geographical delineation for the subregion is the portion of Africa south of the Cunene and Zambezi Rivers: Botswana, Eswatini, Lesotho, Namibia, South Africa, Zimbabwe, and the part of Mozambique that lies south of the Zambezi River. That definition is most often used in South Africa for natural sciences and particularly in guidebooks such as Roberts' Birds of Southern Africa ,

7844-522: The laboratory until 1932 when William Justin Kroll produced it by reducing titanium tetrachloride (TiCl 4 ) with calcium . Eight years later he refined this process with magnesium and with sodium in what became known as the Kroll process. Although research continues to seek cheaper and more efficient routes, such as the FFC Cambridge process , the Kroll process is still predominantly used for commercial production. Titanium of very high purity

7950-431: The material can gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a fatigue limit that guarantees longevity in some applications. The metal is a dimorphic allotrope of a hexagonal close packed α form that changes into a body-centered cubic (lattice) β form at 882 °C (1,620 °F). The specific heat of the α form increases dramatically as it

8056-503: The metal to springback . This is especially true of certain high-strength alloys. Exposure to the oxygen in air at the elevated temperatures used in forging results in formation of a brittle oxygen-rich metallic surface layer called " alpha case " that worsens the fatigue properties, so it must be removed by milling, etching, or electrochemical treatment. The working of titanium is very complicated, and may include Friction welding , cryo-forging , and Vacuum arc remelting . Titanium

8162-403: The most abundant (73.8%). As a metal , titanium is recognized for its high strength-to-weight ratio . It is a strong metal with low density that is quite ductile (especially in an oxygen -free environment), lustrous, and metallic-white in color . Due to its relatively high melting point (1,668 °C or 3,034 °F) it has sometimes been described as a refractory metal , but this

8268-507: The most abundant (73.8% natural abundance ). At least 21 radioisotopes have been characterized, the most stable of which are Ti with a half-life of 63 years; Ti, 184.8 minutes; Ti, 5.76 minutes; and Ti, 1.7 minutes. All other radioactive isotopes have half-lives less than 33 seconds, with the majority less than half a second. The isotopes of titanium range in atomic weight from 39.002  Da ( Ti) to 63.999 Da ( Ti). The primary decay mode for isotopes lighter than Ti

8374-451: The mountains (the stage called "youth"). During this first stage, the terrain is steeper and more irregular. Over time, the currents can carve wider valleys ("maturity") and then start to wind, towering hills only ("senescence"). Finally, everything comes to what is a plain flat plain at the lowest elevation possible (called "baseline") This plain was called by Davis' " peneplain " meaning "almost plain" Then river rejuvenation occurs and there

8480-439: The north and temperate in the south, but also includes humid-subtropical , Mediterranean-climate , highland-subtropical , oceanic, desert, and semi-arid regions. Except for lower parts of Zambia and interior areas of Namibia and Botswana, the region rarely suffers from extreme heat. In addition, the winter presents mostly as mild and dry, except in the southwest. Cool southeasterly winds and high humidity bring cool conditions in

8586-572: The other in the south ( Kingdom of Butua from 1450–1683) which was a smaller entity than the former two, the kingdom was governed by the Torwa dynasty and its capital was situated at Khami . Both states would eventually be absorbed by the powerful Shona state, the Rozwi Empire by 1683. The economy was based on cattle herding, farming, and gold mining. The empire lasted until 1866, which came after droughts and instability. The Mthethwa Paramountcy

8692-530: The oxide with release of hydrogen sulfide . Titanium nitride (TiN) is a refractory solid exhibiting extreme hardness, thermal/electrical conductivity, and a high melting point. TiN has a hardness equivalent to sapphire and carborundum (9.0 on the Mohs scale ), and is often used to coat cutting tools, such as drill bits . It is also used as a gold-colored decorative finish and as a barrier layer in semiconductor fabrication . Titanium carbide (TiC), which

8798-406: The paleogeography through his work "The climates of the geological past" which is considered the father of paleoclimatology . Russian geographers who made great contributions to the discipline in this period were: NM Sibirtsev , Pyotr Semyonov , K.D. Glinka , Neustrayev , among others. The second important process is the theory of evolution by Darwin in mid-century (which decisively influenced

8904-530: The patriarch of Russian geography, Mikhail Lomonosov . In the mid-1750s Lomonosov began working in the Department of Geography, Academy of Sciences to conduct research in Siberia. They showed the organic origin of soil and developed a comprehensive law on the movement of the ice, thereby founding a new branch of geography: glaciology . In 1755 on his initiative was founded Moscow University where he promoted

9010-408: The period of colonial rule, imperial interests controlled the economies of the region and South Africa became the dominant economic power in the late 20th century. The 21st century has seen attempts to create unity among nations in Southern Africa. In spite of democracy, violence , inequality and poverty still persist throughout the region. The region is distinct from the rest of Africa, with

9116-475: The presence of chlorine . In this process, the chlorine gas is passed over a red-hot mixture of rutile or ilmenite in the presence of carbon. After extensive purification by fractional distillation , the TiCl 4 is reduced with 800 °C (1,470 °F) molten magnesium in an argon atmosphere. The van Arkel–de Boer process was the first semi-industrial process for pure Titanium. It involves thermal decomposition of titanium tetraiodide . Titanium powder

9222-505: The presence of titanium dioxide impurities. A variety of reduced oxides ( suboxides ) of titanium are known, mainly reduced stoichiometries of titanium dioxide obtained by atmospheric plasma spraying . Ti 3 O 5 , described as a Ti(IV)-Ti(III) species, is a purple semiconductor produced by reduction of TiO 2 with hydrogen at high temperatures, and is used industrially when surfaces need to be vapor-coated with titanium dioxide: it evaporates as pure TiO, whereas TiO 2 evaporates as

9328-440: The presence of two metal oxides: iron oxide (explaining the attraction to the magnet) and 45.25% of a white metallic oxide he could not identify. Realizing that the unidentified oxide contained a metal that did not match any known element, in 1791 Gregor reported his findings in both German and French science journals: Crell's Annalen and Observations et Mémoires sur la Physique . He named this oxide manaccanite . Around

9434-779: The reality of a region with large urban populations and where food insecurity goes beyond per-capita availability to issues of access and dietary adequacy. Urban food security has been noted as an emerging area of concern in the region, with recent data showing high levels of food insecurity amongst low-income households. In a study of eleven cities in nine countries: Blantyre , Cape Town , Gaborone , Harare , Johannesburg , Lusaka , Maputo , Manzini , Maseru , Durban , and Windhoek , only 17% of households were categorized as 'food-secure' while more than half (57%) of all households surveyed were found to be 'severely food-insecure'. Some factors affecting urban food insecurity include climate change with potential impact on agricultural productivity,

9540-677: The region largely lags behind their Asian counterparts in innovation, foreign direct investment, STEM sciences and research and development . Southern Africa has a wide diversity of ecoregions including grassland , bushveld , karoo , savannah and riparian zones . Even though considerable disturbance has occurred in some regions from habitat loss due to human population density or export-focused development, there remain significant numbers of various wildlife species, including white rhino , lion , African leopard , impala , kudu , blue wildebeest , vervet monkey and elephant . It has complex Plateaus that create massive mountain structures along

9646-873: The regions including political instability, poor governance, droughts, population growth, urbanisation, poverty, low economic growth, inadequate agricultural policies, trade terms and regimes, resource degradation and the recent increase in HIV/AIDS . These factors vary from country to country. For example, the Democratic Republic of the Congo has favourable climatic and physical conditions, but performs far below its capacity in food provision due to political instability and poor governance. In contrast, semi-arid countries such as Botswana and Namibia, produce insufficient food, but successfully achieve food security through food imports due to economic growth, political stability and good governance. The Republic of South Africa

9752-611: The results of research carried out in universities and various other research institutions. Most journals cover a specific publish the research within that field, however unlike human geographers, physical geographers tend to publish in inter-disciplinary journals rather than predominantly geography journal; the research is normally expressed in the form of a scientific paper . Additionally, textbooks, books, and communicate research to laypeople, although these tend to focus on environmental issues or cultural dilemmas. Examples of journals that publish articles from physical geographers are: From

9858-640: The same time, Franz-Joseph Müller von Reichenstein produced a similar substance, but could not identify it. The oxide was independently rediscovered in 1795 by Prussian chemist Martin Heinrich Klaproth in rutile from Boinik (the German name of Bajmócska), a village in Hungary (now Bojničky in Slovakia). Klaproth found that it contained a new element and named it for the Titans of Greek mythology . After hearing about Gregor's earlier discovery, he obtained

9964-567: The study of geography and the training of geographers. In 1758 he was appointed director of the Department of Geography, Academy of Sciences, a post from which would develop a working methodology for geographical survey guided by the most important long expeditions and geographical studies in Russia. The contributions of the Russian school became more frequent through his disciples, and in the nineteenth century we have great geographers such as Vasily Dokuchaev who performed works of great importance as

10070-517: The success of platinum-based chemotherapy, titanium(IV) complexes were among the first non-platinum compounds to be tested for cancer treatment. The advantage of titanium compounds lies in their high efficacy and low toxicity in vivo . In biological environments, hydrolysis leads to the safe and inert titanium dioxide. Despite these advantages the first candidate compounds failed clinical trials due to insufficient efficacy to toxicity ratios and formulation complications. Further development resulted in

10176-409: The universities of the colonial powers and the birth and development of national geographical societies, thus giving rise to the process identified by Horacio Capel as the institutionalization of geography. The exploration of Siberia is an example. In the mid-eighteenth century, many geographers were sent to perform geographical surveys in the area of Arctic Siberia . Among these is who is considered

10282-603: The wealthiest regions of Africa with the greatest potential for economic growth . A chain of mineral resources in Southern Africa stretches from the rich oil fields in northwest Angola, east through the central diamond-mining region in Huambo Province , and into the Copper Belt region of Zambia and Congo. A region of rich mineral deposits continues to the south called the Great Dyke in central Zimbabwe, through

10388-664: The wetter and higher East from the Atlantic Ocean . In addition, the Drakensberg and Eastern Highlands separate the highland areas and coastal plains centred on Mozambique in the north and KwaZulu-Natal in the south, the latter of which are often prone to flooding every few years. In the east, the river systems of the Zambezi and Limpopo basin form natural barriers and sea lanes between Mozambique, South Africa, and Zimbabwe. Across most of southern Africa, apart from

10494-509: The winter. The Namib Desert is the driest area in the region. Altitude plays an outsize role in moderating the temperatures of the South African Highveld , Lesotho , and much of Zambia and Zimbabwe. The prairie region of central and northeast South Africa, the country of Zimbabwe, and parts of Zambia are known as the veldt , divided into the Bushveld and Highveld . There are high temperatures and low rainfall within

10600-481: The work of Friedrich Ratzel , who had academic training as a zoologist and was a follower of Darwin's ideas) which meant an important impetus in the development of Biogeography. Another major event in the late nineteenth and early twentieth centuries took place in the United States . William Morris Davis not only made important contributions to the establishment of discipline in his country but revolutionized

10706-606: The world and a major tourist attraction for the region. Southern Africa includes both subtropical and temperate climates, with the Tropic of Capricorn running through the middle of the region, dividing it into its subtropical and temperate halves. Countries commonly included in Southern Africa include Angola , Botswana , the Comoros , Eswatini , Lesotho , Madagascar , Malawi , Mauritius , Mozambique , Namibia , South Africa , Zambia , and Zimbabwe . In cultural geography ,

10812-504: The years, some the other Southern African nations have invested in economic diversification, and invested public funds into rail, road and air transportation as part of a concerted effort through SADC to boost regional trade and improve communication and transportation. The countries in this region also belong to the Southern Africa Power Pool, which facilitates the development of a competitive electricity market within

10918-521: Was a Shona ( Karanga ) kingdom in what is today Zimbabwe . The capital, which sits near present-day Masvingo , is located at Great Zimbabwe , which are the largest stone structure in precolonial Southern Africa. This kingdom came after the collapse of the Kingdom of Mapungubwe. During the decline of the Kingdom of Zimbabwe, two powers emerged, one in the north ( Kingdom of Mutapa from 1430–1760) which had improved on Zimbabwe's administrative structure; and

11024-414: Was an African state that emerged in the late 18th-century in the region of present-day KwaZulu-Natal . The state was consolidated and extended under the rule of Dingiswayo who produced a disciplined and highly organised army for the first time in the region. The Zulu Kingdom rose under the leadership of Shaka and covered most of present-day KwaZulu-Natal in the 19th century. Internal conflict arose in

11130-438: Was complicated by the settlement of white peoples . After an initial phase from 1945 to 1958, as a consolidation of white power, decolonization succeeded in its achievement when High Commission territories and overseas departments such as Zambia , Malawi , Botswana , Lesotho , Mauritius , Swaziland , Madagascar and the Comoros became independent states from British and French rule. The brutal struggle for independence in

11236-482: Was made in small quantities when Anton Eduard van Arkel and Jan Hendrik de Boer discovered the iodide process in 1925, by reacting with iodine and decomposing the formed vapors over a hot filament to pure metal. In the 1950s and 1960s, the Soviet Union pioneered the use of titanium in military and submarine applications ( Alfa class and Mike class ) as part of programs related to the Cold War. Starting in

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