Platinum-group element geochemistry of the Panjal Traps: constraints on mantle melting and implications for mineral exploration

Forty-two volcanic rocks of the Panjal Traps were analyzed for platinum-group elements (PGE) to investigate magma genesis, high-temperature behaviour, and exploration potential of these elements. The PGE data exhibit substantial variability and show no systematic relation to their low-Ti or high-Ti affinity. Instead, the basalts can be subdivided into PGE-undepleted (group 1) that has ∑PGE > 10 ppb and Cu/Pd < 30000, and PGE-depleted, that consists of a subgroup showing limited (group 2A) or substantial depletion in IPGE relative to Ni (group 2B). The group 1 samples indicate a S-undersaturated history whereas the group 2 samples might have different origins in terms of S-saturation. Fractionation of a tiny amount of sulfide melts (0.075 to 0.1%) from a representative group 1 sample accounts for the chalcophile element patterns observed in the group 2B samples. The relatively high Cu/Pd, unfractionated Ni/Ir, and low PGE abundances observed in the group 2A samples cannot be explained by equilibration of an immiscible sulfide melt alone, and probably requires decomposition of residual sulfides into sulfide melt and a mss in the mantle restite. Our results question the notion that the coexistence of PGE-undepleted and PGE-depleted magmas are prospective in the exploration of magmatic Ni-Cu-(PGE) sulfide mineralization.

Effect of Higher Silicon Content and Heat Treatment on Structure Evolution and High-Temperature Behaviour of Fe-28Al-15Si-2Mo Alloy

This paper describes the structure and properties of cast Fe3Al-based alloy doped with 15 at. % of silicon and 2 at. % of molybdenum. The higher content of silicon is useful for the enhancement of high-temperature mechanical properties or corrosion resistance of iron aluminides but deteriorates their workability due to increased brittleness. It was found that the presence of both alloying elements leads to an increase of values of the high-temperature yield stress in compression. The heat treatment (annealing at 800 °C for 100 h) used for the achievement of phase stability causes the grain coarsening, so the values of the high-temperature yield stress in compression are lower at 600 °C and 700 °C in comparison to values measured for the as-cast state. This stabilization annealing significantly improves the workability/machinability of alloy. Furthermore, the higher silicon content positively affects the values of the thermal expansion coefficient that was found to be lower in the temperature range up to 600 °C compared to alloys with lower content of silicon.

In situ high-temperature behaviour of fluor-elbaite: breakdown conditions and products

The thermal behaviour of a fluor-elbaite from Minas Gerais (Brazil) was investigated at room pressure through in situ high-temperature X-ray powder diffraction (HT-XRPD), until the breakdown conditions were reached. The variations of fluor-elbaite structural parameters (unit-cell parameters and mean bond distances) were monitored together with site occupancies, and two main internal reactions were identified: the thermally-induced Fe oxidation process counterbalanced by (OH)– deprotonation, which starts at 500 °C (773 K), followed by a partial intracrystalline Fe–Al exchange between the octahedrally-coordinated Y and Z sites. The fluor-elbaite breakdown reaction occurs between 850 °C (1123 K) and 900 °C (1173 K). The breakdown products were identified at room temperature by XRPD and the breakdown reaction can be described by the following reaction: tourmaline → B-bearing mullite + hematite + spinel + B-poor (Na, Li, H2O)-bearing glass. Boromullite itself was not observed in the final heating products, and the B-bearing mullite from the breakdown reaction exhibited unit-cell parameters a = 7.5382(2) Å, b = 7.6749(2) Å, c = 2.8385(1) Å, V = 164.22(1) Å3 (space group Pbam) consistent with an approximate Al8.5B1.5Si2O19 composition.

Black box modelling and simulating the dynamic indoor air temperature of a laboratory using autoregressive–moving-average (ARMA) model

<p>Mathematical model representing the dynamic indoor air temperature of a building is important for reducing the time and cost required to test any proposed thermal comfort control algorithm and strategy for that building through computer simulation. There are many types of mathematical model, and each type has its strength(s) and weakness(es). An autoregressive–moving-average (ARMA) model, a type of black box model is used to represent the dynamic indoor air temperature behaviour of industrial instrumentation laboratory at malaysia-japan international institute of technology (MJIIT), universiti teknologi malaysia (UTM) Kuala Lumpur based on the recorded data from the laboratory and minimal physical characteristics knowledge of the laboratory. The ARMA model’s output developed in this research is compared with the actual data recorded from the laboratory for performance measurement. The obtained result shows that the ARMA model is sufficient for modelling and simulating the dynamic indoor air temperature behaviour of the laboratory.</p>

Oxazoline-Methacrylate Graft-Copolymers with Upper Critical Solution Temperature Behaviour in Yubase Oil

Thermoresponsive behavior of polymers in aqueous solutions has been widely studied and utilized in various applications. However, the fundamental understanding on the use of oil soluble polymers in non-aqueous solutions...