A decision support method for designing vegetation layers with minimised irrigation need

Annals of Operations Research - Selecting a vegetation layer design goes along with determining its future irrigation need. Therefore, it is essential to take a design decision that is minimising...     

Combined QCM-D/GE as a tool to characterize stimuli-responsive swelling of and protein adsorption on polymer brushes grafted onto 3D-nanostructures

A combined setup of quartz crystal microbalance and generalized ellipsometry can be used to comprehensively investigate complex functional coatings comprising stimuli-responsive polymer brushes and 3D nanostructures in a dynamic, noninvasive in situ measurement. While the quartz crystal microbalance detects the overall change in areal mass, for instance, during a swelling or adsorption process, the generalized ellipsometry data can be evaluated in terms of a layered model to distinguish between processes occurring within the intercolumnar space or on top of the anisotropic nanocolumns. Silicon films with anisotropic nanocolumnar morphology were prepared by the glancing angle deposition technique and further functionalized by grafting of poly-(acrylic acid) or poly-(N- isopropylacrylamide) chains. Investigations of the thermoresponsive swelling of the poly-(N-isopropylacrylamide) brush on the Si nanocolumns proved the successful preparation of a stimuli-responsive coating. Furthermore, the potential of these novel coatings in the field of biotechnology was explored by investigation of the adsorption of the model protein bovine serum albumin. Adsorption, retention, and desorption triggered by a change in the pH value is observed using poly-(acrylic acid) functionalized nanostructures, although generalized ellipsometry data revealed that this process occurs only on top of the nanostructures. Poly-(N-isopropylacrylamide) is found to render the nanostructures non-fouling properties.     

The solubility of Co in TiO2 anatase and rutile and its effect on the magnetic properties

Co-doped anatase and rutile bulk-samples prepared by the sol-gel technique are found to be paramagnetic at room-temperature. Only further annealing in Ar/H₂ gas results in a ferromagnetic behavior. X-ray diffraction and electron-microscope studies reveal for low doping levels <4% the formation of Co-doped rutile samples and the formation of CoTiO₃ as a new phase. Co₃O₄ can be detected in anatase samples with Co doping levels ?4%. The observed Co oxides are reduced by Ar/H₂ to Co metal. The room-temperature ferromagnetism can therefore be traced back to a segregation of metallic Co.     

Longest Paths and Longest Cycles in Graphs with Large Degree Sums

 Let p(G) and c(G) denote the number of vertices in a longest path and a longest cycle, respectively, of a finite, simple graph G. Define σ₄(G)=min{d(x ₁)+d(x ₂)+ d(x ₃)+d(x ₄) | {x ₁,…,x ₄} is independent in G}. In this paper, the difference p(G)−c(G) is considered for 2-connected graphs G with σ₄(G)≥|V(G)|+3. Among others, we show that p(G)−c(G)≤2 or every longest path in G is a dominating path. Received: August 28, 2000 Final version received: May 23, 2002     

The RuO4-catalysed dihydroxylation, ketohydroxylation and mono oxidation--novel oxidation reactions for the synthesis of diols and alpha-hydroxy ketones

Alpha-hydroxy ketones are versatile intermediates for the synthesis of complex molecular architectures and subunits of a variety of natural products. Different approaches towards the synthesis of this important functional group combination have been elaborated. The present article summarises our research on the field of RuO4-catalysed oxidations of alkenes that resulted in the development of the first RuO4-catalysed ketohydroxylation of olefins. Mechanistic investigations of both dihydroxylation and ketohydroxylation led to the discovery of the first regioselective catalytic mono oxidation of vic-diols, which was applied in a two-step sequence of asymmetric dihydroxylation and regioselective mono oxidation to furnish enantiopure alpha-hydroxy ketones with both predictable regioselectivity and absolute configuration.     

Parahydrogen induced polarization of barbituric acid derivatives: 1H hyperpolarization studies

Homogeneous hydrogenation of barbituric acid derivatives with parahydrogen yields a substantial increase of the (1)H NMR signals of the reaction products. These physiologically relevant compounds were hydrogenated at both ambient and elevated temperatures and pressures using a standard cationic rhodium catalyst. The resulting nonthermal nuclear spin polarization (hyperpolarization) is limited by the spin-lattice relaxation time T(1) of the corresponding nuclei in the products, being shorter than the time constant of the hydrogenation. The signal-to-noise ratio of the NMR spectra could be further increased upon signal averaging the antiphase PHIP signals of 25 successive scans following 30 degrees pulse experiments and a delay of 10 s.