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Study of half-metallicity has been performed in a new series of Mn2ScZ (Z = Si, Ge and Sn) full Heusler alloys using density functional theory with the calculation and implementation of a Hubbard correction term (U).

Summary Previously, nuclear-magnetic-resonance (NMR) carbon-type-analysis data were used to develop a mathematical model of mild thermal conversion (visbreaking) of Athabasca bitumen (Chan et al. 2006). In that work, the major reaction pathways followed during visbreaking were identified. This approach is being extended in the current work to model the visbreaking behaviour of five different oils from different geographical locations around the world. This paper shows the correlation of residue conversion with the contents of different carbon types for five heavy oils from four continents. During visbreaking runs, operators intend to maximize process yields. This is achieved through increasing process severity by raising temperature. However, if the temperature is too high, coke forms. This maximum temperature varies with different crude oils; therefore, as refinery feedstock composition changes, so does the onset of coking temperature. Coke is a hydrocarbon material that has low hydrogen content and is insoluble in the oil. Consequently, this precipitates in the reactor, eventually causing an unscheduled unit shutdown. We have found that contents of specific carbon types in the feed oils correlate with coke formation. This correlation allows prediction of the quantities of coke that will form under the chosen visbreaking (mild thermal) conditions and the "maximum" quantities of coke that would form under coking (severe thermal) conditions.

SynopsisBecause of improved strength-ductility combination over HSLA steels, dual phase steels have recently become of commercial importance to both the sheet users and producers. These steels possess good properties by virtue of their microstructure which consists, typically, of about 15'20 % martensite uniformly distributed in a soft matrix of ferrite. Although, the desired microstructural features of a dual phase steel can be obtained by various process routes, the most economical method is the production of this steel in as hot rolled condition. The sucessful production of dual phase steels in the hot strip mill, however, requires a careful control of process parameters particularly the finishing temperature, the cooling of the sheet on the runout table, the coiling temperature and the subsequent cooling of the coils.As a development effort some commercial heats of dual phase steel in C-Mn-Si-Cr-Mo chemistry have been produced in as hot rolled condition at Rourkela Steel Plant. The effect of coiling temperature and cooling rate on the final structure and properties of the steel has been discussed in detail. All the coils coiled at lower temperatures of about 470° C or less showed dual phase structure with uniform properties where as coiling at about 500 °C or above did not yield the desired microstructure and properties. Possible reasons have been given to explain the effect of coiling temperature on microstructure. Acceleration of the cooling rate of the coil, after coiling, has been found to improve the tensile strength without significantly affecting the ductility of the material.