We report the orientation dependent B K-edge electron-loss near-edge spectroscopy spectra of the isostructural compounds AlB 2 and TiB 2 . The observed differences between the experimental spectra of the borides are discussed in terms of the variation in bonding between the two materials. The orientation dependence is rationalized in terms of the anisotropic nature of the common crystal structure. For a detailed comparison with experiment, we have employed a first-principles method for the calculation of the partial density of states. This method is based on band calculations using the full-potential linearized augmented plane-wave method within density-functional theory. We ascribe the origin of the discrepancies between the broadened ground-state density of states and experiment to the presence of a core hole in the final state. The core-hole effect is self-consistently accounted for via the use of ab initio supercell calculations, leading to improved agreement with experiment particular in certain crystallographic directions, where screening of the core hole is expected to be much reduced. Additionally a detailed analysis of the valence-band structure, charge-transfer effects, and covalency in the diborides has been undertaken.

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In August 2019, a new bus fleet of 36 electric and 58 hybrid buses were implemented in Trondheim, Norway. This paper examines the carbon footprint of electrified city buses, by addressing the achieved and potential reduction for the new bus fleet. Important aspects such as geographical location of production, charging electricity mix, and impact from production and operation on lifetime emissions, are also examined. A meta-analysis on life cycle assessment studies was undertaken to investigate greenhouse gas emissions and energy demand in different parts of bus production. This is followed by the production of a bus model using the findings and comparing electrified buses with diesel and HVO buses. The models were then used in a case study of the bus fleet in Trondheim, to understand the specific parameters affecting the carbon footprint. The results show that the overall carbon footprint has been considerably reduced (37%) by implementing biofuel and electrified buses, and that a further reduction of 52% can be achieved through full electrification. The operation emissions for the fleet were found to be 49 g CO2-eq/person-km, which is lower than the average city bus and passenger car in Norway.