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Structure of the FeMoco active site of nitrogenase The molybdenum cofactor (pictured) is composed of a molybdenum-free organic complex called molybdopterin, which has bound an oxidized molybdenum(VI) atom through adjacent sulfur (or occasionally selenium) atoms. Except for the ancient nitrogenases, all known Mo-using enzymes use this cofactor.
Molecular solids can be either ductile or brittle, or a combination depending on the crystal face stressed. [5] [11] Both ductile and brittle solids undergo elastic deformation till they reach the yield stress. [8] [11] Once the yield stress is reached, ductile solids undergo a period of plastic deformation and eventually fracture. Brittle ...
Solids with purely metallic bonding are characteristically ductile and, in their pure forms, have low strength; melting points can [inconsistent] be very low (e.g., Mercury melts at 234 K (−39 °C)). These properties are consequences of the non-directional and non-polar nature of metallic bonding, which allows atoms (and planes of atoms in a ...
Some nonmetals (black P, S, and Se) are brittle solids at room temperature (although each of these also have malleable, pliable or ductile allotropes). From left to right in the periodic table, the nonmetals can be divided into the reactive nonmetals and the noble gases. The reactive nonmetals near the metalloids show some incipient metallic ...
Liners have been made from many materials, including various metals [48] and glass. The deepest penetrations are achieved with a dense, ductile metal, and a very common choice has been copper. For some modern anti-armor weapons, molybdenum and pseudo-alloys of tungsten filler and copper binder (9:1, thus density is ≈18 Mg/m 3) have
The least brittle structural ceramics are silicon carbide (mainly by virtue of its high strength) and transformation-toughened zirconia. A different philosophy is used in composite materials, where brittle glass fibers, for example, are embedded in a ductile matrix such as polyester resin. When strained, cracks are formed at the glass–matrix ...
Molybdenum disulfide (or moly) is an inorganic compound composed of molybdenum and sulfur. Its chemical formula is MoS 2. The compound is classified as a transition metal dichalcogenide. It is a silvery black solid that occurs as the mineral molybdenite, the principal ore for molybdenum. [6] MoS 2 is relatively unreactive.
The main GCP phase is γ'. Almost all superalloys are Ni-based because of this phase. γ' is an ordered L1 2 (pronounced L-one-two), which means it has a certain atom on the face of the unit cell, and a certain atom on the corners of the unit cell. Ni-based superalloys usually present Ni on the faces and Ti or Al on the corners.