p-Carborane: a new cage spacer for photoactive metal polypyridine dyads

The first example of a binuclear ruthenium complex involving the p-carborane framework in the bridging ligand is reported. The bridging ligand is a symmetric linear array comprising a central p-carborane unit, two p-phenylene spacers, and two 5-yl-2,2'-bipyridine coordinating units. A homobinuclear Ru(II) complex, with 2,2'-bipyridine as peripheral ligands, was synthesized and characterized. The Ru(II)-Ru(III) mixed-valence species, obtained by partial oxidation, has been investigated with steady-state and time-resolved techniques in CH3CN. The rate of photoinduced electron transfer is 2.3 x 10(8) s(-1).     

Linear Complexity Solution of Parabolic Integro-differential Equations

The numerical solution of parabolic problems with a pseudo-differential operator by wavelet discretization in space and hp discontinuous Galerkin time stepping is analyzed. It is proved that an approximation for u(T) can be obtained in N points with accuracy for any integer p ≥ 1 in work and memory which grows logarithmically-linear in N.Supported in part IHP Network Breaking Complexity of the EC (contract number HPRN-CT-2002-00286) with support by the Swiss Federal Office for Science and Education under grant No. BBW 02.0418.Funded by the Swiss National Science Foundation (Grant PBEZ2-102321).     

Multi-level Monte Carlo finite volume methods for nonlinear systems of conservation laws in multi-dimensions

We extend the multi-level Monte Carlo (MLMC) in order to quantify uncertainty in the solutions of multi-dimensional hyperbolic systems of conservation laws with uncertain initial data. The algorithm is presented and several issues arising in the massively parallel numerical implementation are addressed. In particular, we present a novel load balancing procedure that ensures scalability of the MLMC algorithm on massively parallel hardware. A new code is described and applied to simulate uncertain solutions of the Euler equations and ideal magnetohydrodynamics (MHD) equations. Numerical experiments showing the robustness, efficiency and scalability of the proposed algorithm are presented.     

Patterning of YBCO films by excimer-laser ablation

Thin films of YBa₂Cu₃O₇ coated with a photoresist have been patterned by means of XeCl- and KrF-excimer-laser light projection. Lines with widths down to 3.5 m have been fabricated without degradation in T _c and j _c. The technique is compared with wet-chemical etching and with ns and fs excimer-laser patterning of films without a protective layer.     

Opportunities and Limitations of Nanoagrochemicals

Nanoagrochemicals conceived based on safe-by-design principles could provide, besides yield increases, real benefits for the environment due to lower losses of agrochemicals to wind drift and rainwater run-off, and lower toxicity to non-target organisms. As an emerging new technology rather than ‘just another’ active ingredient, nanoagrochemicals should be evaluated and compared to conventional products using multiple criteria, including the production costs, efficiency, mode of action, degradability, and (lack of) effects on non-target organisms. Current studies on nanopesticides suggest, on average, ca. 31 % more efficiency and ca. 43 % less toxicity on non-target organisms. Observations of a 5–10-fold increase in efficiency in laboratory studies need validation in the field. The most significant challenges for nanoagrochemicals today are to produce them at competitive costs and overcome the regulatory obstacles to register products containing nanomaterials.     

Biodegradable High-Density Polyethylene-like Material

We report a novel polyester material generated from readily available biobased 1,18-octadecanedicarboxylic acid and ethylene glycol possesses a polyethylene-like solid-state structure and also tensile properties similar to high density polyethylene (HDPE). Despite its crystallinity, high melting point (T_m=96 °C) and hydrophobic nature, polyester-2,18 is subject to rapid and complete hydrolytic degradation in in vitro assays with isolated naturally occurring enzymes. Under industrial composting conditions (ISO standard 14855-1) the material is biodegraded with mineralization above 95 % within two months. Reference studies with polyester-18,18 (T_m=99 °C) reveal a strong impact of the nature of the diol repeating unit on degradation rates, possibly related to the density of ester groups in the amorphous phase. Depolymerization by methanolysis indicates suitability for closed-loop recycling.