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The general theme of this thesis is a study of electronic communication within porphyrin oligomers. Chapter 1 reviews briefly the porphyrins: their chemical structure, advantages of their use in supramolecular chemistry and some of their basic photo-physical properties. Chapter 2 discusses a study of the origin of an unusual intensity of certain IR bands in two porphyrin oligomer cations. The study uses a polarised time-resolved IR (TR-IR) to understand relative orientation of the intensified vibrations, corroborated with DFT calculations. Coupling between individual IR modes and with the electronic band is documented by 2D-IR spectroscopy and further understanding of the system dynamics upon excitation is understood thanks to the detail kinetic analysis. Chapter 3 focuses on aromaticity. The basis of aromaticity as a concept is reviewed and examples of theoretical and experimental investigations of aromaticity of some π-conjugated species is presented. The experimental part discusses the preparation of large globally (anti)aromatic species via oxidation of the otherwise globally non-aromatic nanorings and its evaluation with NMR. All these studies are supported with DFT calculations corroborating the correct interpretation. Chapter 4 discuses the design and synthesis of a large Möbius-strip-shaped porphyrin nanoring. Firstly, a brief overview of the concept of Möbius aromaticity is reviewed, followed by examples of various designs and reported syntheses of Möbius molecules. This is followed by the design and synthesis and study of two novel nanorings, one which is suspected of adopting Möbius confirmation.

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The contribution presents an analysis of a rate-independent non-local damage model, recently proposed by (Mielke and Roubicek, 2006). An analytical as well as numerical solution of a simple one-dimensional bifurcation problem is performed, demonstrating that, for the elementary localization test, the model is free of pathological features., Comment: This paper has been withdrawn by the authors due incorrect form of the local-displacement diagram shown in Figure 3(b); the correct solution always exhibits snapback at the structural level. The corrected and significantly expanded version of the manuscript is available at arXiv:1412.5539. The authors would like to apologize for any inconvenience caused

This paper presents an experimental and numerical study on creasing behavior of corrugated paper boards. Experiments have been carried out on corrugated paper board and its constituent papers. Finite element simulations have been carried out on a plane-strain model, incorporating Hill’s plasticity criterion. The finite element simulations are found to be in good agreement with experimental observations up to initial buckling. The study presented here is intended to help in determining the optimum creasing depth to prevent cracking of paper boards during creasing and folding operations while manufacturing packaging boxes.

Continuum damage models describe the changes of material stiffness and strength, caused by the evolution of defects, in the framework of continuum mechanics. In many materials, a fast evolution of defects leads to stress–strain laws with softening, which creates serious mathematical and numerical problems. To regularize the model behaviour, various generalized continuum theories have been proposed. Integral-type non-local damage models are often based on weighted spatial averaging of a strain-like quantity. This paper explores an alternative formulation with averaging of the displacement field. Damage is assumed to be driven by the symmetric gradient of the non-local displacements. It is demonstrated that an exact equivalence between strain and displacement averaging can be achieved only in an unbounded medium. Around physical boundaries of the analysed body, both formulations differ and the non-local displacement model generates spurious damage in the boundary layers. The paper shows that this undesirable effect can be suppressed by an appropriate adjustment of the non-local weight function. Alternatively, an implicit gradient formulation could be used. Issues of algorithmic implementation, computational efficiency and smoothness of the resolved stress fields are discussed.

In this work, building on the earlier work briefly reviewed above, a rate-dependent mixed- mode interface element is implemented within a multi-layer beam environment consisting of two- or three-nodded beam finite elements. The presented model is verified against experimental results for mode I delamination (DCB test) and computationally more expensive models which use plane-strain 2D finite elements with significantly higher number of degrees of freedom. Special attention is dedicated to the choice of optimum solution procedure for the non-linear problem and reducing the computation time.

The paper describes modeling of initial anisotropy of wood in the framework of microplane theory. The performance of the proposed model is demonstrated on one numerical example. In the example a 3D finite element analysis of a wooden specimen loaded in tension is carried out at the meso scale. The results are compared with the test results and the comparison shows reasonably good agreement.