Microstructure evaluation of titanate based layered perovskites: Constrained vs. free sintering

Sem resum

High-resolution Geophysics in the Investigation of the Inner Structure of Walls and Columns of Batalha Abbey

Knowledge of walls and other structural elements construction characteristics and techniques is mandatory in the maintenance and restoration of historical buildings. Such information is obtained from documents or by comparing with monuments of the same period. Documents are difficult to obtain and comparison with other buildings can be inaccurate. The use of direct invasive techniques may be considered but they are likely to damage structures or compromise buildings stability. Thus, indirect high-resolution methods are adapted to these investigations. This work describes a GPR and a Seismic Transmission Tomography survey to investigate the walls and columns of the 14th century Batalha Abbey (UNESCO heritage site). High-resolution GRP data revealed the dimensions and thicknesses of different walls and the structure and nature of materials inside them. The Seismic Transmission Tomography survey, supported by high-resolution photogrammetry scanning for accurate positioning of sources and geophones, was carried out to investigate the Abbey columns. Seismic velocities distribution inside the columns characterized their interior and clarified the nature of the materials used. Columns construction followed the same technique and used the same materials. However, each column depicts a different velocity zonation that could correspond to different stages of deterioration for each one

HRTEM Studies of Stress Assisted Sintered BaLa4Ti4O15.

21 Suppl

Structure and dielectric characterization of a new A-site deficient La5/3MgTaO6 perovskite

The crystal structure of new A-site deficient Lasj3MgTa06 perovskite was investigated by neutron, X-ray and electron diffraction. Neutron and X-ray powder diffraction spectra were refined in the monoclinic 12/m space group, with the parameters of the unit cell a = 5.6304(2)A, b = 5.6226(2) A, c = 7.9434(2)A and p= 90.04(1)". This structural model presumes a random distribution of the vacancies and takes into account both a rock salt-type Mg2+ /Ta5+ cation ordering and a-a-co configuration of the octahedral tilting. Electron diffraction showed that the crystal structure is more complex at the local level due to a short-range vacancy ordering. This observation in combination with the symmetry analysis leads to the conclusion that the C2/m symmetry with 2.J2ap x 2.J2ap x 2ap supercell is more adequate for the description of the crystal structure in the local level. Dielectric measurements performed in a wide frequency range were correlated with the crystal structure and compared with other ordered double perovskites. Far-infrared spectroscopy was used to characterize the lattice contribution to the dielectric response at the microwave frequencies. The complex dielectric function was evaluated and extrapolated down to the gigahertz range. The effect of the vacancies on the intrinsic dielectric losses is discussed based on the spatial phonon correlation model

Lost Cities in the Digital Era: the case of pre-earquake Lisbon

Lisbon was ruined by a major earthquake on November 1st, 1755. The seismic shocks, the tsunami, and the fire that followed massively destroyed its urban and architectural fabric, and its written and iconographic memory was seriously curtailed. There is a significant historiography on pre-earthquake Lisbon, particularly dating from the last 30 years. However, it was vital to convert this knowledge into a global outlook on the city which was lost. Virtual archaeology provided the necessary tools, from a technical and a methodological perspective. City and Spectacle: A Vision of Pre-Earthquake Lisbon was thus devised as a virtual re-creation/simulation of all the area of Lisbon destroyed by the 1755 earthquake and on which the new city was built. Developed at the Centre for Art History and Artistic Research (CHAIA), of the University of Évora, this project aims to re-create the physical, social, and cultural dimensions of Lisbon on the eve of the earthquake, through the use of Second Life®/OpenSimulator technology. The documentary sources available, either primary or secondary, are being tested in an interactive and immersive model and in a collaborative real-time environment, so as to give the project an innovative laboratory dimension. Also, the fact that users are able to interact with the model as well as with other users in realtime transforms the data itself and, as a result, the object of study. The Lisbon that is being re-created/simulated is not just a working hypothesis presented as a glimpse into the collective memory, but is also a means for contemporaneous fruition of this memory

The Evolution of Educational Technology in Veterinary Anatomy Education.

"All learning is in the learner, not the teacher." Plato was right. The adage has passed the test of time and is still true in an era where technology accompanies us in not only professional but also recreational life every day, everywhere. On the other hand, the learner has evolved and so have the sources being used to satisfy curiosity and learning. It therefore appears intuitive to embrace these technological advances to bring knowledge to our pupils with the aim to facilitate learning and improve performance. It must be clear that these technologies are not intended to replace but rather consolidate knowledge partly acquired during more conventional teaching of anatomy. Veterinary medicine is no outlier. Educating students to the complexity of anatomy in multiple species requires that three-dimensional concepts be taught and understood accurately if appropriate treatment is to be set in place thereafter. Veterinary anatomy education has up to recently walked diligently in the footsteps of John Hunter's medical teaching using specimens, textbooks, and drawings. The discipline has yet to embrace fully the benefits of advancement being made in technology for the benefit of its learners. Three-dimensional representation of anatomy is undeniably a logical and correct way to teach whether it is through the demonstration of cadaveric specimen or alternate reality using smartphones, tablets, headsets or other digital media. Here we review some key aspects of the evolution of educational technology in veterinary anatomy