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Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Evaluating all these arguments and counter-arguments over whether to continue use of the term “heavy metal” or to abandon it, this book adopts the criteria presented by Ali and Khan (2018), which are found to be scientifically consistent, precise, and logical, and follows these to enlist the metals fulfilling these conditions as “heavy metals.” Table 1.4 presents the list of “heavy metals” according to this classification along with their atomic numbers and densities. The atomic numbers range from 23 (vanadium) to 94 (plutonium) with the other heavy metals coming in between. However, only those elements are categorized as heavy metals which satisfy the three criteria laid down by Ali and Khan (2018). For example, though scandium, titanium, and yttrium are naturally occurring metals having atomic numbers of 21, 22, and 39, and thereby fulfill criteria (i) and (ii) of being metals having an atomic number greater than 20, these are excluded from the heavy metal category because their densities are less than 5 g cm–3 (scandium 2.99, titanium 4.54, and yttrium 4.47 g cm–3) and therefore fail to satisfy criterion (iii). On the other hand, technetium (atomic number 43, density 11.50 g cm–3) and promethium (atomic number 61; density 7.30 g cm–3) are not considered because they do not occur naturally and, therefore, do not meet criterion (i). The densities of the 51 elements categorized as heavy metals range from 5.24 g cm–3 (europium) to 22.6 g cm–3 (osmium).
Cryofixation of brown algae for transmission electron microscopy
Published in Bénédicte Charrier, Thomas Wichard, C.R.K. Reddy, Protocols for Macroalgae Research, 2018
Chikako Nagasato, Christos Katsaros, Taizo Motomura
Note 2: Osmium tetroxide is highly hazardous. When handling osmium tetroxide, wear gloves and carry out all steps in the fume hood. To avoid contamination of freezers and refrigerators with OsO4, put the cryogenic vials in a metallic can with a cover and seal it with plastic tape.
List of Chemical Substances
Published in T.S.S. Dikshith, and Safety, 2016
Osmium is an extremely dense, blue-gray, hard but brittle metal that remains lustrous at high temperatures. Osmium possesses quite remarkable chemical and physical properties. It has the highest melting point and the lowest vapor pressure in the olatinum family. Osmium is highly volatile, extremely toxic, and is rarely used in its pure state, often alloyed with other metals. Those alloys are utilized in high-wear applications. Osmium alloys such as osmiridium are very hard and, along with other platinum group metals, are used in the tips of fountain pens, instrument pivots, and electrical contacts, as they can resist wear from frequent operation.
Influence of magnetic field on the wave propagation response of functionally graded (FG) beam lying on elastic foundation in thermal environment
Published in Waves in Random and Complex Media, 2022
Farzad Ebrahimi, Ali Seyfi, Mostafa Nouraei, Parisa Haghi
According to the aforementioned special properties of the FGMs made with metals and ceramics, we are encouraged to analyze this type of FG structure in the framework of wave propagation. Osmium and Silicon Carbide (SiC) are employed in this investigation as novel metals and ceramics respectively due to their interesting properties. As a matter of fact, British chemist Smithson Tennant discovered osmium in 1803 in the residue left when crude platinum was dissolved by aqua regia. Osmium is one of the densest elements in the world. It is a lustrous, bluish white, hard metal and can be brittle even at a high temperature. Within the platinum group, osmium has the highest melting point and the lowest vapor pressure. Osmium has only a few uses. It is used to produce very hard alloys for fountain pen tips, instrument pivots, needles and electrical contacts. It is also used in the chemical industry as a catalyst [37]. Also, Silicon Carbide is the only chemical compound of carbon and silicon with perfect properties including low density, high strength, high thermal conductivity, high hardness, high elastic modulus, low thermal expansion which caused the Silicon Carbide to become a distinctive ceramic with various applications in fixed and moving turbine components, seals, bearings, heat exchangers and hot gas flow liners [38–40]. Taking into account all these astounding and applicable properties of the Osmium and SiC, investigating the mechanical behaviors of these materials as a FG structure can be a high-priority title.