First-principles study of structures, elastic and optical properties of single-layer metal iodides under strain

The structure, elastic, electronic and optical properties of two-dimensional (2D) MI2 (M = Pb, Ge, Cd) under strain are systematically studied by the first-principles method. It is proved that the monolayer structure of 2D-MI2 is stable by phonon spectra. Moreover, the large ideal strain strength (40%), the large range of strain and the elastic constants of far smaller than other 2D materials indicate that the single-layer PbI2 and GeI2 possess excellent ductility and flexibility. By applying appropriate strain to the structure of 2D-MI2, the band gaps of single-layer MI2 can be effectively controlled (PbI2: 1.04 ∼ 3.03 eV, GeI2: 0.43 ∼ 2.99 eV and CdI2: 0.54 ∼ 3.36 eV). It is found that the wavelength range of light absorbed by these three metal iodides is 82–621 nm, so 2D-MI2 has great absorption intensity for ultraviolet light in a large wavelength range, and the strain of structure can effectively regulate the optical parameters.

A Study of Electromagnetic Absorption Performance of Modern Biomass Wall Tile

Electromagnetic elimination was used to eliminate unwanted radiation that may interface with machinery or affect human health. The use of microwave absorbers has become necessary for an environment with a safe electromagnetic wave level. The objectives of this project are to design a microwave absorber as a modern biomass wall tile and to investigate the absorbing performance of the modern wall tile absorbers with different materials. The absorber was designed with similar shapes and different biomass materials. The concept of modern wall tile had been applied to design the absorbers in terms of their shape and dimension by using biomass materials. Biomass materials such as kenaf and coconut coir were used in the study due to their lightweight and environmental-friendly material behavior. The simulation was done using CST Suite Studio software to predict the preliminary result of the absorbers. The proposed designs of the modern wall tile from the CST simulation are then fabricated while the mixtures of the materials are moulded into a microwave absorber. NRL Arch free space method was used to determine the absorption performance of the modern wall tile absorbers at a frequency range from 1GHz to 12GHz. Both results of the simulation and free space measurement are analyzed and discussed. This study showed that absorber KCA has the best performance among all the absorbers with the absorption of more than -10 dB. The mixture of biomass material with carbon has a great absorption performance compared to the mixture of biomass material without carbon.

Influence of the surroundings areas in the microclimates of Santo André City – Brazil and Indication of Bioclimatic Strategies for Buildings

The characterization of the climate of Santo André and its weather data are essential instruments for the study of implantation, both of new buildings and solutions of retrofit, as well as for the elaboration of projects of urban interventions or degraded areas occupation. In this study, meteorological weather data were obtained by meteorological stations in Santo André, a municipality located in the region of ABC Paulista (São Paulo State), for five different points of the city in order to evaluate the different micro climates and the influence of the surroundings in microclimates and an climate file in .epw format was developed for analysed bioclimatic strategies for buildings. Results show temperature and humidity variations among the five microclimates analyzed, as a consequence of the following actions: replacement of vegetation by constructions, asphalt, concrete and other impermeable surfaces, increased air pollution which cause a great absorption of solar radiation, forming a barrier for air circulation and of pollutant gases into the atmosphere creating urban heat island effects.