Carbon steelCarbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: no minimum content is specified or required for chromium, cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium, zirconium, or any other element to be added to obtain a desired alloying effect; the specified minimum for copper does not exceed 0.40%; or the specified maximum for any of the following elements does not exceed the percentages noted: manganese 1.
AlkaneIn organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula . The alkanes range in complexity from the simplest case of methane (), where n = 1 (sometimes called the parent molecule), to arbitrarily large and complex molecules, like pentacontane () or 6-ethyl-2-methyl-5-(1-methylethyl) octane, an isomer of tetradecane ().
KinshasaKinshasa (kɪnˈʃɑːsə; kinʃasa; Kinsásá), formerly Léopoldville, is the capital and largest city of the Democratic Republic of the Congo. Once a site of fishing and trading villages situated along the Congo River, Kinshasa is now one of the world's fastest growing megacities. The city of Kinshasa is also one of the DRC's 26 provinces. Because the administrative boundaries of the city-province cover a vast area, over 90 per cent of the city-province's land is rural in nature, and the urban area occupies a small but expanding section on the western side.
MirrorA mirror or looking glass is an object that reflects an . Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner.
DiphthongA diphthong (ˈdɪfθɒŋ,_ˈdɪp- ; , ), also known as a gliding vowel, is a combination of two adjacent vowel sounds within the same syllable. Technically, a diphthong is a vowel with two different targets: that is, the tongue (and/or other parts of the speech apparatus) moves during the pronunciation of the vowel. In most varieties of English, the phrase "no highway cowboy" (noʊ_ˈhaɪweɪ_ˈkaʊbɔɪ) has five distinct diphthongs, one in every syllable.
MaskA mask is an object normally worn on the face, typically for protection, disguise, performance, or entertainment, and often employed for rituals and rites. Masks have been used since antiquity for both ceremonial and practical purposes, as well as in the performing arts and for entertainment. They are usually worn on the face, although they may also be positioned for effect elsewhere on the wearer's body. In art history, especially sculpture, "mask" is the term for a face without a body that is not modelled in the round (which would make it a "head"), but for example appears in low relief.
StatelessnessIn international law, a stateless person is someone who is "not considered as a national by any state under the operation of its law". Some stateless people are also refugees. However, not all refugees are stateless, and many people who are stateless have never crossed an international border. On November 12, 2018, the United Nations High Commissioner for Refugees stated there are about 12 million stateless people in the world. The status of a person who might be stateless ultimately depends on the viewpoint of the state with respect to the individual or a group of people.
