Portfolio optimization with early announced discrete dividends

In this article we include discrete dividends in the stock price model and solve the corresponding generalized portfolio optimization problem. For this, we develop a new discrete dividend model that allows for the possibility of early announcement and ensures that the drop of the stock price at the ex-dividend date equals the dividend. The resulting portfolio problem can be solved explicitly for both the wealth and the trading strategy. We find that the resulting optimal portfolio process differs from the Merton strategy.     

Synthesis,characterization and solubility studies of four new highly water soluble 1,3,5-triaza-7-phosphaadamantane (PTA) salts and their gold(I) complexes

The synthesis of new water soluble N-alkylated derivatives of 1,3,5-triaza-7-phosphaadamantane is presented. The compounds were characterized by means of NMR and IR spectroscopy, mass spectrometry, high resolution mass spectrometry, elemental analysis and X-ray diffraction analysis. The water solubility of these compounds was found to be up to an astonishing 1450 g/L. Several different reactions were performed utilizing these highly interesting compounds as starting materials. It was shown that the substitution of the counter ion can be performed easily. Also transformations at the PTA framework were possible, as shown by an ester cleavage example. To prove that the resulting PTA derivatives are competent as ligands for transition metals, gold(I) complexes were synthesized, using Au(tht)Cl as the metal source. The resulting gold(I) complexes were characterized by ¹H NMR and IR spectroscopy, mass and high resolution mass spectrometry or elemental analysis.     

The first Pd(II) complex of a non-heteroatom stabilised carbene ligand

Di(p-tolyl)diazomethane reacts with the tripyrrinate TrpyPdOAc(F) 1 after activation with NaBAr(F) to yield the first stable Pd(II) complex 2 of a non-Arduengo type carbene ligand, which could be characterised by X-ray crystallography.     

Synthesis of spherical polymer and titania photonic crystallites

The fabrication of small structured spherical particles that are essentially small photonic crystals is described. The particles are 1-50 microm in diameter and are porous with nearly close-packed monodisperse pores whose size is comparable to the wavelength of light. The solid matrix of the particles is titania, which provides a large refractive index contrast between the particle matrix and pores. The particles are made by encapsulating polymer colloidal particles in emulsion droplets of hexanes in which a titanium alkoxide precursor is dissolved. Subsequent osmotic removal of the hexanes from the droplets and condensation of the alkoxide precursor leads to spherical aggregates of polymer spheres with titania filling the spaces between the polymer spheres. The polymer particles are then burned out leaving behind the desired porous titania particles. The size and structure of the pores and high refractive index of the titania matrix are expected to produce particles that are very efficient scatterers of light, making them useful as pigments.     

Partitioning of dual-lipidated peptides into membrane microdomains: lipid sorting vs peptide aggregation

The lateral membrane organization and phase behavior of the lipid mixture DMPC(di-C(14))/DSPC(di-C(18))/cholesterol (0-33 mol %) with and without an incorporated fluorescence-labeled palmitoyl/farnesyl dual-lipidated peptide, BODIPY-Gly-Cys(Pal)-Met-Gly-Leu-Pro-Cys(Far)-OMe, which represents a membrane recognition model system for Ras proteins, was studied by two-photon excitation fluorescence microscopy. Measurements were performed on giant unilamellar vesicles (GUVs) over a large temperature range, ranging from 30 to 80 degrees C to cover different lipid phase states (all-gel, fluid/gel, liquid-ordered, all-fluid). At temperatures where the fluid-gel coexistence region of the pure binary phospholipid system occurs, large-scale concentration fluctuations appear. Incorporation of cholesterol levels up to 33 mol % leads to a significant increase of conformational order in the membrane system and a reduction of large domain structures. Adding the peptide leads to dramatic changes in the lateral organization of the membrane. With cholesterol present, a phase separation is induced by a lipid sorting mechanism owing to the high affinity of the lipidated peptide to a fluid, DMPC-rich environment. This phase separation leads to the formation of peptide-containing domains with high fluorescence intensity that become progressively smaller with decreasing temperature. As a result, the local concentration of the peptide increases steadily within the confines of the shrinking domains. At the lowest temperatures, where the acyl-chain order parameter of the membrane has already drastically increased and the membrane achieves a liquid-ordered character, an efficient lipid sorting mechanism is no longer supported and aggregation of the peptide into small clusters prevails. We can conclude that palmitoyl/farnesyl dual-lipidated peptides do not associate with liquid-ordered or gel-like domains in phase-separated bilayer membranes. In particular, the study shows the interesting ability of the peptide to induce formation of fluid microdomains at physiologically relevant cholesterol concentrations, and this effect very much depends on the concentration of fluid vs ordered lipid molecules.