Sulfur core composition

The fully characterization of both simple or more complex (but well defined in terms of active center composition) iron-sulfur proteins leads to a well of information. The compilation of typical spectroscopic features of the known basic iron-sulfur structures enables a preliminary characterization of centers in a new simple situation or even in some more complex ones. EPR spectroscopy of the iron-sulfur cores in the appropriated oxidation states have characteristics that can be used to readily distinguish certain type of centers58). This technique has also been used to analyse components in complex systems. However the use of EPR as the sole technique can be misleading, when applied to new situations as we have seen for the case of the [3 Fe—xS] core. In this particular case only the conjunction of EPR and Mossbauer can lead to a proper characterization27 33 34 55). 

Figure 5. Sulfur isotope compositions of sulfuric acid aerosols in South Pole ice core samples. Aerosols from two eruptions, Pinatubo and AD 1259 that injected SO2 into the stratosphere have anomalously fractionated S- S- S (39).

A growing body of data on Antarctic ice cores shows that the history of volcanic eruptions is resolvable year-by-year (38). The record includes dated explosive events such as Cerro Hudson in 1991, Pinatubo-1991, Agung-1963, Krakatoa-1883, Tambora-1815, and a 1259 AD eruption of unknown location. Analysis of the oxygen and sulfur isotope composition of aerosol particles frozen in the polar refrigerator provides a proxy of atmospheric chemistry applicable to early Earth. Aerosols from Cerro Hudson, the smallest of the explosive eruptions, have normal sulfur isotope compositions with no anomalous fractionation of (39). Cerro Hudson s eruption cloud did not break... 

Chen et al. reported the synthesis of sulfur/polythiophene composites with core/shell structure through an in-situ chemical oxidative polymerization method for LIB cathode. Using a low viscosity electrolyte of 1,3-dioxolane (DOL)/dimethoxy ethane (DME), the composite with 72 wt% of sulfur was cycled at a current density of 100 mA/g and retained 74% of its initial capacity (1120mAh/g) after 80 cycles [47]. Polythiophene (PTh) coated with ultrathin MnO nanosheets was synthesized through one-step aqueous/ organic interfacial method for LIB anode application. The as-synthesized MnOj-polythiophene nanocomposite delivered a reversible capacity of 720 rnAh/g and retained 500 mAh/g after 100 cycles at a high current density of 500 mA/g [48]. 

The high resistivity of Inconel 600 (11 OjtI 0 8 Dm) demanded the application of this material as a composite with a central aluminum core. The aluminum was totally enclosed in Inconel 600 so that the Inconel was only exposed to sulfur and polysulfides. In a test over more than three years, cells with a composite current collector of this kind suffered from a high capacity decline. Post-test analysis showed that Inconel sustained polysulfide attack with the formation of a duplex nickel and chromium sulfide layer on the current collector surface. 

A huge number of transition metal-sulfur clusters have been synthesized,36 most of which have been obtained based on the self-assembly methods. On the other hand, to construct the cluster cores with the desired metal-sulfur compositions and connecting schemes, rational pathways leading to the high-yield syntheses of tailored metal-sulfur clusters have recently been explored. Fragment condensations have been demonstrated to be the powerful methods to obtain such clusters numerously,37 some examples of which are shown below. 

Analysis of the nny 82 ammunition as previously detailed shows that it uses a mercuric corrosive primer. Analysis of the Chinese 351/73 ammunition revealed that it has a copper-coated iron-jacketed bullet with an iron core and a lead tip, the cartridge case is steel with a brown colored lacquered finish, a brass primer cup, and the propellant is single based with DPA, 2 x nitrodiphenylamines, camphor, and contains no inorganic additives, and the discharged primer composition is antimony, potassium, chlorine, mercury, tin, sulfur, iron, manganese, phosphorus, zinc, and lead in descending order (lead, antimony, mercury type). 

Silicates provide further evidence for the unusual origin of lAB-IIICD. While differentiated silicates might be expected in association with iron meteorites, silicates in lAB-IIICD irons are broadly chondritic (Mittlefehldt et al., 1998 Benedix et al., 2000 see Chapter 1.11). Models for the origins of lAB-IIICD iron meteorites include crystallization of a sulfur- and carbon-rich core in a partially differentiated object (Kracher, 1985 McCoy et al., 1993), breakup and reassembly of a partially differentiated object at its peak temperature (Benedix et al., 2000), or crystal segregation in isolated impact melt pools on the surface of a porous chondritic body (Wasson and Kallemeyn, 2002). A recent compilation of the chemical compositions of lAB and IIICD iron meteorites may be found in Wasson and KaUemeyn (2002). 

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