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Understanding the relationship between fibril morphology and corneal biomechanics is crucial for predicting the ocular response to physiological and surgical loads. In this study, we developed a finite element model of the corneal strip to investigate the effect of fibril crimp parameters, area fraction and orientation on the nonlinear stress-strain behaviour. The fibrils were modelled as Ogden materials with a Gaussian distributed crimp degree, while the matrix was set linear elastic. Uniaxial tension simulations were performed to analyse the evolution of fibril deformation and stress with the applied load. The result showed good agreement with the experimental data reported in the literature and captured the three stages of corneal response. Increasing the fibril area fraction, and decreasing the crimp degree and angular deviation from the loading axis resulted in higher corneal stiffness. Interestingly, the stressstrain behaviour was insensitive to changes in crimp amplitude and period at a constant crimp degree. These findings provide novel insights into the corneal structure-function relationships and highlight the potential of multi-scale computational models for predicting ocular biomechanics. [ABSTRACT FROM AUTHOR]

The ionization energy spectra and electron momentum distributions of formamide were investigated using the high-resolution electron momentum spectrometer in combination with high level calculations. The observed ionization energy spectra and electron momentum distributions were interpreted using symmetry adapted cluster-configuration interaction theory, outer valence Green function, and DFT-B3LYP methods. The ordering of 10a′ and 2a″ orbitals of formamide was assigned unambiguously by comparing the experimental electron momentum distributions with the corresponding theoretical results, i.e., 10a′ has a lower binding energy. In addition, it was found that the low-frequency wagging vibration of the amino group at room temperature has noticeable effects on the electron momentum distributions. The equilibrium-nuclear-positions-approximation, which was widely used in electron momentum spectroscopy, is not accurate for formamide molecule. The calculations based on the thermal average can evidently improve the agreement with the experimental momentum distributions. [ABSTRACT FROM AUTHOR]

Electron momentum spectroscopy and symmetry adapted cluster-configuration interaction (SAC-CI) theory were combined to study electron correlation effects in nitrous oxide molecule (N2O). The SAC-CI General-R method accurately reproduced the experimental ionization spectrum. This bench-marked method was also introduced for calculating the momentum distributions of N2O Dyson orbitals. Several calculated momentum distributions with different theoretical methods were compared with the high resolution experimental results. In the outer-valence region, Hartree-Fock (HF), density functional theory (DFT), and SAC-CI theory can well describe the experimental momentum distributions. SAC-CI presented a best performance among them. In the inner-valence region, HF and DFT cannot work well due to the severe breaking of the molecular orbital picture, while SAC-CI still produced an excellent description of experimental momentum profiles because it can accurately take into account electron correlations. Moreover, the thermally averaged calculation showed that the geometrical changes induced by the vibration at room temperature have no noticeable effects on momentum distribution of valence orbitals of N2O. [ABSTRACT FROM AUTHOR]