7,040 research outputs found
Ab Initio Molecular Dynamics Simulations of Methylammonium Lead Iodide Perovskite Degradation by Water
No full textProtecting organohalide perovskite thin films from water and ambient humidity represents a paramount challenge for the commercial uptake of perovskite solar cells and, in general, of related optoelectronic devices. Therefore, understanding the perovskite/water interface is of crucial importance. As a step in this direction, here we present ab initio molecular dynamics simulations aimed at unraveling the atomistic details of the interaction between the methylammonium lead iodide (MAPbI(3)) perovskite surfaces and a liquid water environment. According to our calculations, MAI-terminated surfaces undergo a rapid solvation process, driven by the interaction of water molecules with Pb atoms, which prompts the release of I atoms. PbI2-terminated surfaces, instead, seem to be more robust to degradation, by virtue of the stronger (shorter) Pb I bonds formed on these facets. We also observe the incorporation of a water molecule into the PbI2-terminated slab, which could represent the first step in the formation of an intermediate hydrated phase. Interestingly, PbI2 defects on the PbI2-terminated surface promote the rapid dissolution of the exposed facet. Surface hydration, which is spontaneous for both MAI- and PbI2-terminated slabs, does not modify the electronic landscape of the former, while the local band gap of the PbI2-exposing model widens by similar to 0.3 eV in the interfacial region. Finally, we show that water incorporation into bulk MAPbI(3) produces almost no changes in the tetragonal structure of the perovskite crystal (similar to 4% volume expansion) but slightly opens the band gap. We believe that this work, unraveling some of the atomistic details of the perovskite/water interface, may inspire new interfacial modifications and device architectures with increased stabilities, which could in turn assist the commercial uptake of perovskite solar cells and optoelectronic devices
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Drumheller, AB
No full textNotes - A history of the Ursaline order in Drumheller, AB from 1935 to 1985 (2 pages)Drumhelle
Souvenir of Edmonton, AB
No full textBooklet - Souvenir of Edmonton - The Capital City of Alberta. Collection of photographs in a green cover tied with string, Edmonton, AB (48 pages
Ab initio study of the structural, vibrational and optical properties of potential parent structures of nitrogen-doped lutetium hydride
No full textThe recent report of near-ambient conditions superconductivity in a
nitrogen-doped lutetium hydride has inspired a large number of experimental
studies with contradictory results. We model from first principles the physical
properties of the possible parent structures of the reported superconductor,
LuH and LuH. We show that only the phonon band structure of LuH can
explain the reported Raman spectra due to the presence of hydrogens at the
interstitial octahedral sites. However, this structure is stabilized by
anharmonicity only above 6 GPa. We find that the intriguing color change with
pressure in the reported superconductor is consistent with the optical
properties of LuH, which are determined by the presence of an undamped
interband plasmon. The plasmon blue-shifts with pressure and modifies the color
of the sample without requiring any structural phase transition. Our findings
suggest that the main component in the experiments is LuH with some extra
hydrogen atoms at octahedral sites. None of LuH and LuH superconduct at
high temperatures
Aves de pampas y campos
No full textCrítica detallada del libro Azpiroz, AB, 2012: `Aves de las pampas y campos de Argentina, Brasil y Uruguay. Una guía de identificación" en el cual se destacan sus fortalezas y se discuten sus debilidades.Fil: Codesido, Mariano. Consejo Nacional de Invest. Científ.y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Bs. As; Argentina
Ab initio pair potentials at metal-ceramic interfaces
No full textA systematic approach is proposed to obtain the interfacial interatomic potentials. By inverting ab initio adhesive energy curves for the metal-MgO ceramic interfaces, We derive interfacial potentials between Ag and O2-, Ag and Mg2+, Al and O2-, Al and Mg2+. The interfacial potentials, obtained from this method, demonstrate general features of bondings between metal atoms and ceramic ions
Perceptions of pre- and post-event impacts of PEI 2014 year-long celebrations
No full textThis study examines Canadian perceptions of pre- and post-event impacts of the PEI 2014 Celebrations using the 2013 and 2015 surveys of PEI residents and other Canadians conducted by the Centre for Tourism Research. Overall, results indicate that Canadians’ awareness of, knowledge about, and attitudes toward the 1864 Charlottetown Conference and the PEI 2014 Celebrations increased and positively changed over time. The research also suggests that event organizers and/or destination tourism managers need to put greater emphasis on the “socio-cultural aspects” of the event such as community participation and cultural identity, and make an effort to increase tourism volume and value in order to obtain strong support from residents and be successful
Ab initio analysis of the topological phase diagram of the Haldane model
No full textWe present an ab initio analysis of a continuous Hamiltonian that maps into the celebrated Haldane model. The tunneling coefficients of the tight-binding model are computed by means of two independent methods—one based on the maximally localized Wannier functions, and the other through analytic expressions in terms of gauge-invariant properties of the spectrum—that provide a remarkable agreement and allow one to accurately reproduce the exact spectrum of the continuous Hamiltonian. By combining these results with the numerical calculation of the Chern number, we are able to draw the phase diagram in terms of the physical parameters of the microscopic model. Remarkably, we find that only a small fraction of the original phase diagram of the Haldane model can be accessed, and that the topological insulator phase is suppressed in the deep tight-binding regime
Ultra-low-power, class-AB, CMOS four-quadrant current multiplier
No full textA class-AB four-quadrant current multiplier constituted by a class-AB current amplifier and a current splitter which can handle input signals in excess of ten times the bias current is presented. The proposed circuit operation is based on the exponential characteristic of BJTs or subthreshold MOSFETs. The multiplier is designed using the latter devices and achieves very low power consumption. Simulation results show that from a 0.65 V supply, the proposed circuit consumes 12.4 nW static power while less than 30 dB total harmonic distortion is achieved for an input modulation index up to 10.Microelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
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