Nanotubular boron-carbon heterojunctions

Linear nanotubular boron-carbon heterojunctions are systematically constructed and studied with the help of ab initio total energy calculations. The structural compatibility of the two classes of materials is shown, and a simple recipe that determines all types of stable linear junctions is illustrated in some detail. Our results also suggest the compatibility of various technologically interesting types of nanotubular materials, leading to different types of nanotubular compound materials, and pointing out the possibility of wiring nanotubular devices within heterogeneous nanotubular networks.     

Multireference configuration interaction study of bromocarbenes

Multireference configuration interaction (MRCI) calculations of the lowest singlet X(1A') and triplet ?((3)A') states as well as the first excited singlet ?((1)A') state have been performed for a series of bromocarbenes: CHBr, CFBr, CClBr, CBr(2), and CIBr. The MRCI calculations were performed with correlation consistent basis sets of valence triple-ζ plus polarization quality, employing a full-valence active space of 18 electrons in 12 orbitals (12 and 9, respectively, for CHBr). Results obtained include equilibrium geometries and harmonic vibrational frequencies for each of the electronic states, along with ?((3)A') ← X((1)A') singlet-triplet gaps and ?((1)A') ← X((1)A') transition energies. Comparisons have been made with previous computational and experimental results where available. The MRCI calculations presented in this work provide a comprehensive series of results at a consistent high level of theory for all of the bromocarbenes.     

Numerical simulation and experimental investigation of the elastocaloric cooling effect in sputter-deposited TiNiCuCo thin films

The exploitation of the elastocaloric effect in superelastic shape memory alloys (SMA) for cooling applications shows a promising energy efficiency potential but requires a better understanding of the non-homogeneous martensitic phase transformation. Temperature profiles on sputter-deposited superelastic \({\mathrm {Ti_{55.2}Ni_{29.3}Cu_{12.7}Co_{2.8}}}\) shape memory alloy thin films show localized release and absorption of heat during phase transformation induced by tensile deformation with a strong rate dependence. In this paper, a model for the simulation of the thermo-mechanically coupled transformation behavior of superelastic SMA is proposed and its capability to reproduce the mechanical and thermal responses observed during experiments is shown. The procedure for experiment and simulation is designed such that a significant temperature change from the initial temperature is obtained to allow potential cooling applications. The simulation of non-local effects is enabled by the use of a model based on the one-dimensional Müller–Achenbach–Seelecke model, extended by 3D mechanisms such as lateral contraction and by non-local interaction, leading to localization effects. It is implemented into the finite element software COMSOL Multiphysics, and comparisons of numerical and experimental results show that the model is capable of reproducing the localized transformation behavior with the same strain rate dependency. Additionally to the thermal and the mechanical behavior, the quantitative prediction of cooling performance with the presented model is shown.     

On structural stability for semiflows

Some results on structural stability which are known to hold for flows of a compact manifold are extended to semiflows of a Banach space.