Osteopenie und pathologische Frakturen bei einem Jugendlichen mit Laktoseintoleranz und hohem Oxalatkonsum

Zusammenfassung: Wir stellen einen Jugendlichen mit Osteopenie und pathologischen Frakturen vor. Der Fall soll auf folgende Punkte aufmerksam machen: Eine adäquate Kalziumzufuhr während Kindheit und Adoleszenz ist für die Entwicklung einer normalen "peak bone mass" von ausschlaggebender Bedeutung. Es ist wahrscheinlich, dass moderne Ernährungsgewohnheiten (Junkfood und Softdrinks) bisher noch zu wenig erkannte Auswirkungen auf die Gesundheit unserer Knochen habe

Optimizing gold nanoparticle size and shape for the fabrication of sers substrates by means of the langmuir–blodgett technique

The Langmuir–Blodgett technique, in which a layer of nanoparticles is spread at the water/air interface and further transferred onto a solid support, is a versatile approach for the preparation of SERS substrates with a controllable arrangement of hotspots. In a previous work, we demonstrated that fine-tuning the lateral packing and subsequent seed growth of 10 nm gold nanoparticles led to a quasi-resonant enhanced in the SERS signal of a test analyte. Here, we explore further enhancements by modifying the size and shape of the spread gold nanoparticles in order to take advantage of the inherent interparticle repulsion mechanisms present at the interface. We show that the size of the used nanoparticles is also a determinant factor, which cannot be compensated by the subsequent electroless growth. We also show that, although the seeded growth leads to rough hotspots, the sensitivity can be optimized by self-assembling urchin-shaped nanoparticles, with a roughness that is fine-tuned a priori. Our results suggest an intriguing correlation between surface homogeneity and SERS signal enhancement, indicating that regular substrates will have the optimal performance

Quasi Regular Polyhedra and Their Duals with Coxeter Symmetries Represented by Quaternions I

In two series of papers we construct quasi regular polyhedra and their duals which are similar to the Catalan solids. The group elements as well as the vertices of the polyhedra are represented in terms of quaternions. In the present paper we discuss the quasi regular polygons (isogonal and isotoxal polygons) using 2D Coxeter diagrams. In particular, we discuss the isogonal hexagons, octagons and decagons derived from 2D Coxeter diagrams and obtain aperiodic tilings of the plane with the isogonal polygons along with the regular polygons. We point out that one type of aperiodic tiling of the plane with regular and isogonal hexagons may represent a state of graphene where one carbon atom is bound to three neighboring carbons with two single bonds and one double bond. We also show how the plane can be tiled with two tiles; one of them is the isotoxal polygon, dual of the isogonal polygon. A general method is employed for the constructions of the quasi regular prisms and their duals in 3D dimensions with the use of 3D Coxeter diagrams.Comment: 22 pages, 16 figure

Tailoring plasmonic response by Langmuir-Blodgett gold nanoparticle templating for the fabrication of SERS substrates

Nanoparticle self-assembly is a robust and versatile strategy for the development of functional nanostructured materials, offering low-cost and scalable methods that can be fine-tuned for many different specific application. In this work, we demonstrate a pathway for the fabrication of tailorable quasitwo- dimensional lattices of gold nanoparticles to be used in Surface Enhanced Raman Scattering (SERS) detection of biomolecules. As a first step, nanoparticles are spread as a monolayer at the water/ air interface, compressed to a target lateral density in a Langmuir-Blodgett technique, and transferred to a properly functionalized substrate surface. Once firmly adhered to the substrate, the lattice of nanoparticles can be directly used or be further processed using electroless gold deposition to let the nanoparticle grow thus tuning the plasmonic response and SERS enhancement. Compared to direct deposition or self-assembly methods, our protocol enables to obtain consistent results and much higher coverage of Au nanoparticles thanks to the active control of the surface pressure of the spread monolayer

Error-Free 10.7 Gb/s Digital Transmission over 2 km Optical Link Using an Ultra-Low-Voltage Electro-Optic Modulator

We demonstrate the feasibility of 10.7 Gb/s error-free (BER < 10-12) optical transmission on distances up to 2 km using a recently developed ultra-low-voltage commercial Electro-Optic Modulator (EOM) that is driven by 0.6 Vpp and with an optical input power of 1 mW. Given this low voltage operation, the modulator could be driven directly from the detectors’ board signals without the need of any further amplification reducing significantly the power dissipation and the material budget

Inter-site Coulomb interaction and Heisenberg exchange

Based on exact diagonalization results for small clusters we discuss the effect of inter-site Coulomb repulsion in Mott-Hubbard or charge transfer insulators. Whereas the exchange constant J for direct exchange is substantially enhanced by inter-site Coulomb interaction, that for superexchange is suppressed. The enhancement of J in the single-band models holds up to the critical value for the charge density wave (CDW) instability, thus opening the way for large values of J. Single-band Hubbard models with sufficiently strong inter-site repulsion to be near a CDW instability thus may provide `physical' realizations of t-J like models with the `unphysical' parameter ratio J/t=1.Comment: Revtex file, 4 PRB pages, with 5 embedded ps-files. To appear in PRB, rapid communications. Hardcopies of figures or the entire manuscript may also be obtained by e-mail request to: [email protected]