Soil-structure interaction of tunnel-structures under consideration of far- and near-field effects

The response of a tunnel structure under a moving and oscillating dynamic load can be calculated by means of a hybrid Integral–Transformation–Method–FEM approach. In the ITM approach analytical solutions of ideal geometries of the infinite continuum are superposed such that the wave–number impedance and transfer–function at the interior of a circular tunnel can be calculated efficiently. By this means the infinite continuum can be coupled to an arbitrary tunnel structure which is modelled by the FEM with corresponding form–functions. In order to reduce the effort for the coupling, the characteristics of the analytically given transfer–functions which can be split into near– and far–fields is taken into account. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Laser ultrasonic receivers based on organic photorefractive polymer composites

We present two laser ultrasonic receivers based on organic photorefractive polymer composites with 2-[4-bis(2-methoxyethyl)aminobenzylidene]malononitrile (AODCST) or 2-dicyanomethylen-3-cyano-5,5-dimethyl-4-(4′-dihexylaminophenyl)-2,5-dihydrofuran nonlinear optical chromophores. Experimental results show sensitivities of the ultrasonic receivers of ~9.5 × 10^?8 nm (W/Hz)^0.5 for both composites, and a faster response time (~60 ms) for the AODCST-based laser ultrasonic receiver. We show that such LUS detectors are highly suitable for contactless thickness measurements of aluminum, steel sheets and defect detection with an accuracy of 100 μm.     

Stabilizing gold adatoms by thiophenyl derivatives: a possible route toward metal redispersion

Tris(phenylthio)benzene molecules have been synthesized in order to explore their ability to trap single Au adatoms on an Au(111) surface. The resulting metal-organic complexes have been characterized with low-temperature scanning tunneling microscopy and infrared reflection absorption spectroscopy; possible structure models have been derived from density functional calculations. Upon room temperature deposition, the thiophenyl derivatives form dimer structures, comprising two molecules and six Au adatoms. Below 100 K, isolated molecules are found as well that have trapped up to six Au atoms. On the basis of the experimental results and calculated formation energies of the complexes, we discuss potential applications of the thioethers for the redispersion of metals on a catalyst surface. First experiments performed on Au particle ensembles prepared on alumina thin films suggest that the molecular ligands are indeed able to change the distribution of gold on the oxide surface.     

Structure-property relations and thermodynamic properties of monoclinic petalite, LiAlSi(4)O(10)

Structure-property relations of monoclinic petalite, LiAlSi(4)O(10), were determined by experiment and atomistic modeling based on density functional theory. The elastic stiffness coefficients were measured between room temperature and 570?K using a combination of the plate-resonance technique and resonant ultrasound spectroscopy. The thermal expansion was studied between 100 and 740?K by means of dilatometry. The heat capacity between 2 and 398?K has been obtained by microcalorimetry using a quasi-adiabatic calorimeter. The experimentally determined elastic stiffness coefficients were employed to benchmark the results of density functional theory based model calculations. The values in the two data sets agreed to within a few GPa and the anisotropy was very well reproduced. The atomistic model was then employed to predict electric field gradients, the lattice dynamics and thermodynamic properties. The theoretical charge density was analyzed to investigate the bonding between atoms.     

Ultimate turbulent Taylor-Couette flow

The flow structure of strongly turbulent Taylor-Couette flow with Reynolds numbers up to Re(i)=2×10(6) of the inner cylinder is experimentally examined with high-speed particle image velocimetry (PIV). The wind Reynolds numbers Re(w) of the turbulent Taylor-vortex flow is found to scale as Re(w)∝Ta(1/2), exactly as predicted by Grossmann and Lohse [Phys. Fluids 23, 045108 (2011).] for the ultimate turbulence regime, in which the boundary layers are turbulent. The dimensionless angular velocity flux has an effective scaling of Nu(ω)∝Ta(0.38), also in correspondence with turbulence in the ultimate regime. The scaling of Nu(ω) is confirmed by local angular velocity flux measurements extracted from high-speed PIV measurements: though the flux shows huge fluctuations, its spatial and temporal average nicely agrees with the result from the global torque measurements.     

Two new antimicrobial metabolites from the endophytic fungus, Seimatosporium sp

Two new acaranoic acids, named seimatoporic acid A and B (1, and 2), together with six known compounds, R-(-)-mellein (3), cis-4-hydroxymellein (4), trans-4-hydroxymellein (5), 4R-hydroxy-5-methylmellein (6), (-)-5-hydroxymethylmellein (7), and ergosterol (8) were isolated from an endophytic fungus, Seimatosporium sp, by a bioassay-guided procedure. The structures of the new compounds have been assigned from analysis of the 1H and 13C NMR spectra, DEPT, and by 2D COSY, HMQC, HMBC and NOESY experiments. A mixture of compounds 1 and 2 showed strong antifungal activity against Botrytis cinerea, Septoria tritici, and Pyricularia oryzae.     

Synthesis of electronically modified Ru-based neutral 16 VE allenylidene olefin metathesis precatalysts

Electronic modifications within Ru-based olefin metathesis precatalysts have provided a number of new complexes with significant differences in reactivity profiles. So far, this aspect has not been studied for neutral 16 VE allenylidenes. The first synthesis of electronically altered complexes of this type is reported. Following the classical dehydration approach (vide infra) modified propargyl alcohols were transformed to the targeted allenylidene systems in the presence of PCy?. The catalytic performance was investigated in RCM reaction (ring closing metathesis) of benchmark substrates such as diallyltosylamide and diethyl diallylmalonate.     

Marginal-sum equations and related fixed-point problems

A marginal-sum equation of order p≥2$p\ge 2$ is a system of nonlinear equations which in turn are linear equations for polynomials of degree p$p$ in p$p$ variables. Marginal-sum equations typically arise in the construction of a multiplicative tariff in actuarial mathematics.