Multiscale damage analyis for steel structures

An approach to model the deterioration of steel structures is presented by transferring the results of a continuum damage mechanics analysis to an extended beam model which can account for the loss of structural integrity. Damage starts at the microscopic level by the initiation, growth and coalescence of voids with decreasing material resistance followed by the formation of microcracks at the mesoscale. Nevertheless, the material behavior can be sufficiently modelled on a phenomenological basis taking into account viscoplasticity, hardening effects and damage evolution. The associated model parameters are identified with the help of an evolutionary algorithm adapting numerical to experimental results. Using the finite element method a nonlocal formulation of the damage variable is required to obtain mesh-independent results by structural analysis. The maximum element size is limited by the small magnitude of the internal length. Therefore, numerical analyses of large scale 3D steel structures are computationally expensive. To reduce the effort a beam element is proposed to account for the plastic hinges and the loss of resistance in the course of damage evolution. The corresponding relationship of bending moment and curvature bases on the continuum damage mechanics model. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Euler discretization for a class of nonlinear optimal control problems with control appearing linearly

We investigate Euler discretization for a class of optimal control problems with a nonlinear cost functional of Mayer type, a nonlinear system equation with control appearing linearly and constraints defined by lower and upper bounds for the controls. Under the assumption that the cost functional satisfies a growth condition we prove for the discrete solutions Hölder type error estimates w.r.t. the mesh size of the discretization. If a stronger second-order optimality condition is satisfied the order of convergence can be improved. Numerical experiments confirm the theoretical findings.     

Frames of exponentials and sub-multitiles in LCA groups

In this note, we investigate the existence of frames of exponentials for $L^2(\mathrm{\Omega })$ in the setting of LCA groups. Our main result shows that sub-multitiling properties of $\mathrm{\Omega }?\stackrel{?}{G}$ with respect to a uniform lattice Γ of $\stackrel{?}{G}$ guarantee the existence of a frame of exponentials with frequencies in a finite number of translates of the annihilator of Γ. We also prove the converse of this result and provide conditions for the existence of these frames. These conditions extend recent results on Riesz bases of exponentials and multitilings to frames.     

Density of the Set of Generators of Wavelet Systems

Given a function ψ in the affine (wavelet) system generated by ψ, associated to an invertible matrix a and a lattice Γ, is the collection of functions In this paper we prove that the set of functions generating affine systems that are a Riesz basis of ${\cal L}^2({\Bbb R}^d)$ is dense in We also prove that a stronger result is true for affine systems that are a frame of In this case we show that the generators associated to a fixed but arbitrary dilation are a dense set. Furthermore, we analyze the orthogonal case in which we prove that the set of generators of orthogonal (not necessarily complete) affine systems, that are compactly supported in frequency, are dense in the unit sphere of with the induced metric. As a byproduct we introduce the p-Grammian of a function and prove a convergence result of this Grammian as a function of the lattice. This result gives insight in the problem of oversampling of affine systems.     

Time-dependent density functional theory molecular dynamics simulation of doubly charged uracil in gas phase

We use time-dependent density functional theory and Born-Oppenheimer molecular dynamics methods to investigate the fragmentation of doubly ionized uracil in gas phase. Different initial electronic excited states of the dication are obtained by removing electrons from different inner-shell orbitals of the neutral species. We show that shape-equivalent orbitals lead to very different fragmentation patterns revealing the importance of the intramolecular chemical environment. The results are in good agreement with ionion coincidence measurements of uracil collision with 100 keV protons.     

The conserved protein kinase-A target motif in synapsin of Drosophila is effectively modified by pre-mRNA editing

Background  

Synapsins are abundant synaptic vesicle associated phosphoproteins that are involved in the fine regulation of neurotransmitter release. The Drosophila member of this protein family contains three conserved domains (A, C, and E) and is expressed in most or all synaptic terminals. Similar to mouse mutants, synapsin knock-out flies show no obvious structural defects but are disturbed in complex behaviour, notably learning and memory.     

Electrochemical characterization of screen-printed carbonaceous electrodes for the determination of peroxidase activity in novel screen-printed flow-through modules

A novel totally screen-printed flow-through cell for immunoanalysis is presented. It contained screen-printed carbonaceous electrodes, which allowed the determination of peroxidase activity through the electrochemical reduction of p-benzoquinone. As different electrode materials differ strongly in their electrochemical properties, electrodes resulting from various screen-printable carbonaceous pastes were characterized using the hydroquinone/ p-benzoquinone redox couple. For most of the electrodes, cyclic voltammogram peak separations of between 550 and 670 mV were observed indicating only quasi-reversible electrochemical behavior. This was confirmed by variation of the peak separation with scan rate. Heterogeneous electron transfer rates of ca. 0.5 - 1 x 10(-3) cm s(-1) and electrochemical activation energies of ca. 20 kJ mol(-1) were found. These flow-through cells were not only applied to electrochemical peroxidase activity determinations but also, in combination with a separate detector, as affinity reactors. After biotinylation of screen-printed layers, streptavidin and then biotinylated peroxidase could be bound. However, as signals were only 10-20% of those obtained with a column filled with biotinylated glass beads, only the screen-printed electrochemical detector was applied to the detection of antibodies against the African Swine Fever Virus.     

A one-step route to 4-hydroxy-2,3-diaryl-3,4-dihydro-1 (2 )-isoquinolones

A new procedure for the synthesis of 2,3-diaryl-3,4-dihydro-4-hydroxy-1 (2 )-isoquinolones is described in which the -isomer predominates. Dehydration leads to 2,4-diarylisocarbostyrils.