Optimization of Fishing Strategies in Space and Time as a Non-convex Optimal Control Problem

The behavior of a fishing fleet and its impact onto the biomass of fish can be described by a nonlinear parabolic diffusion–reaction equation. Looking for an optimal fishing strategy leads to a non-convex optimal control problem with a bilinear control action. In this work, we present such an optimal control formulation, prove its well-posedness and derive first- and second-order optimality conditions. These results provide a basis for tailored finite element discretization as well as for Newton type optimization algorithms. First numerical test problems show typical features as so-called No-Take-Zones and maximal fishing quota (total allowable catches) as parts of an optimal fishing strategy.     

Carboxylic‐Acid‐Passivated Metal Oxide Nanocrystals: Ligand Exchange Characteristics of a New Binding Motif

Ligand exchange is central in the processing of inorganic nanocrystals (NCs) and requires understanding of surface chemistry. Studying sterically stabilized HfO₂ and ZrO₂ NCs using ¹H solution NMR and IR spectroscopy as well as elemental analysis, this paper demonstrates the reversible exchange of initial oleic acid ligands for octylamine and self‐adsorption of oleic acid at NC surfaces. Both processes are incompatible with an X‐type binding motif of carboxylic acids as reported for sulfide and selenide NCs. We argue that this behavior stems from the dissociative adsorption of carboxylic acids at the oxide surface. Both proton and carboxylate moieties must be regarded as X‐type ligands yielding a combined X₂ binding motif that allows for self‐adsorption and exchange for L‐type ligands.     

A monolithic finite element discretization for coupled Darcy-Stokes flow

We consider a Stokes system and a Darcy system in a porous media, mutually coupled together by the the well-known Beaver-Joseph-Saffman interface conditions. Standard approaches use different finite elements in the two parts in order to account for the different stability properties of the two equation systems. In contrast to this, we use standard equal-order finite elements in both parts. Stability is obtained by adding local projection terms (LPS) to the Galerkin formulation. We formulate the scheme and give an a priori estimate. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

FINITE ELEMENTS WITH LOCAL PROJECTION STABILIZATION FOR INCOMPRESSIBLE FLOW PROBLEMS

In this paper we review recent developments in the analysis of finite element methods for incompressible flow problems with local projection stabilization （LPS）. These methods preserve the favourable stability and approximation properties of classical residual-based stabilization （RBS） techniques but avoid the strong coupling of velocity and pressure in the stabilization terms. LPS-methods belong to the class of symmetric stabilization techniques and may be characterized as variational multiscale methods. In this work we summarize the most important a priori estimates of this class of stabilization schemes developed in the past 6 years. We consider the Stokes equations, the Oseen linearization and the NavierStokes equations. Furthermore, we apply it to optimal control problems with linear（ized） flow problems, since the symmetry of the stabilization leads to the nice feature that the operations ＂discretize＂ and ＂optimize＂ commute.     

Dithiolene complexes and the nature of molybdopterin

The development of the coordination chemistry of dithiolene ligands is summarised, together with a consideration of the electronic structure of complexes of these ‘non-innocent’ ligands. This information provides a context for a consideration of the role of dithiolenes in natural systems, i.e. as the ligand that binds molybdenum (or tungsten) at the catalytic centre of an extensive series of enzymes. These enzymes catalyse the transfer of an oxygen atom to or from the substrate: e.g. the sulfite oxidases catalyse the conversion of sulfite to sulfate and the nitrate reductases catalyse the conversion of nitrate to nitrite. The nature of the catalytic centres of several of these enzymes has been determined and each involves one or two ‘molybdopterin’ (MPT) cofactors bound to a mononuclear metal centre via their dithiolene group. The biosynthesis of MPT is described and, given its nature, possible roles for this moiety in the function of the oxotransferase enzymes are discussed. The review concludes with a consideration of the coordination chemistry that has been stimulated by the present knowledge of the nature and function of the catalytic centres of these enzymes.     

The ion gating effect: using a change in flexibility to allow label free electrochemical detection of DNA hybridisation

A label free electrochemical method of detecting DNA hybridisation is presented based on the change in flexibility between a single strand of DNA and a duplex causing an ion-gating effect where hybridisation opens up the electrode to access of ions.     

Protein electrochemistry using aligned carbon nanotube arrays

The remarkable electrocatalytic properties and small size of carbon nanotubes make them ideal for achieving direct electron transfer to proteins, important in understanding their redox properties and in the development of biosensors. Here, we report shortened SWNTs can be aligned normal to an electrode by self-assembly and act as molecular wires to allow electrical communication between the underlying electrode and redox proteins covalently attached to the ends of the SWNTs, in this case, microperoxidase MP-11. The efficiency of the electron transfer through the SWNTs is demonstrated by electrodes modified with tubes cut to different lengths having the same electron-transfer rate constant.     

OptiDose: Computing the Individualized Optimal Drug Dosing Regimen Using Optimal Control

Journal of Optimization Theory and Applications - Providing the optimal dosing strategy of a drug for an individual patient is an important task in pharmaceutical sciences and daily clinical...     

Asymmetric Construction of Alkaloids by Employing a Key ω-Transaminase Cascade

An ω-transaminase-triggered intramolecular aza-Michael reaction has been employed for the preparation of cyclic β-enaminones in good yield and excellent enantio- and diastereoselectivity, starting from easily accessible prochiral ketoynones and commercially available enzymes. The powerful thermodynamic driving force associated with the spontaneous aza-Michael reaction effectively displaces the transaminase reaction equilibrium towards product formation, using only two equivalents of isopropylamine. To demonstrate the potential of this methodology, this biocatalytic aza-Michael step was combined with annulation chemistry, affording unique stereo-defined fused alkaloid architectures.     

Study of the Ternary Complex Formation Between Vanadium(III), Dipicolinic Acid and Small Blood Serum Bioligands

Ternary complex formation reactions were studied between vanadium(III), dipicolinic acid and small molecular weight blood serum components: lactic, oxalic, citric and ortophosphoric acids. The electromotive force measurement permitted us to determine the chemical speciation of the complexes formed. In the vanadium(III)–dipicolinic acid–lactic acid system the complexes detected were: V(dipic)(lac), V(dipic)(lac)(OH)⁻ and V(dipic)(lac)(OH)₂^2-(\mathrm{OH})_{2}^{2-}. In the vanadium(III)–dipicolinic acid–oxalic acid system the observed complexes were: V(dipic)(ox)⁻, V(dipic)(ox)(Hox)²⁻ and V(dipic)(ox)₂^3-(\mathrm{ox})_{2}^{3-}. In the vanadium(III)–dipicolinic acid–citric acid system the complexes V(dipic)(Hcit)⁻, V(dipic)(cit)²⁻, V(dipic)(cit)(OH)³⁻, V(dipic)(cit)(OH)₂^4-(\mathrm{OH})_{2}^{4-} and V(dipic)(cit)(OH)₃^5-(\mathrm{OH})_{3}^{5-} were detected. Finally in the vanadium(III)–dipicolinic acid–phosphoric acid system the complexes V(dipic)(H₂PO₄) and V(dipic)(HPO₄)⁻ were observed. The UV-vis spectra allowed us to perform a qualitative characterization of the complexes formed in aqueous solution.