Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Population. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Micro-optical realization of arrays of selectively addressable dipole traps: a scalable configuration for quantum computation with atomic qubits.

Abstract: We experimentally demonstrate novel structures for the realization of registers of atomic qubits: We trap neutral atoms in one- and two-dimensional arrays of far-detuned dipole traps obtained by focusing a red-detuned laser beam with a microfabricated array of microlenses. We are able to selectively address individual trap sites due to their large lateral separation of $125\text{ }\ensuremath{\mu}\mathrm{m}$. We initialize and read out different internal states for the individual sites. We also create two interleaved sets of trap arrays with adjustable separation, as required for many proposed implementations of quantum gate operations.

Electron transport and back reaction in nanocrystalline TiO2 films prepared by hydrothermal crystallization

Abstract: The electron transport and back reaction in nanocrystalline TiO2 films prepared at low temperature using a new hydrothermal crystallization method on conductive glass and plastic substrates have been investigated by intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS). The hydrothermal method enables the preparation of crack-free TiO2 thick films and at the same time enhances the electron transport compared to films prepared by low-temperature sintering, providing a path towards efficient photoelectrode materials for flexible dye-sensitized solar cells. UV/ozone treatment of the films enables the removal of residual organics left from the hydrothermal preparation process. Since these organics represent surface states that mediate the back reaction of electrons, the electron lifetime is increased by their removal, while the electron transport is not enhanced significantly. High-temperature sintering of the hydrothermally prepared films leads to both ...

Orange, red, yellow: Biosynthesis of azaphilone pigments in Monascus fungi

Abstract: Monascus azaphilone pigments (MonAzPs) are very widely used as food colorants, but their biosynthetic pathway has remained poorly characterized for more than half a century. In this study, the individual steps of MonAzPs biosynthesis in Monascus ruber M7 were elucidated by a combination of targeted gene knockouts, heterologous gene expression, and in vitro chemical and enzymatic reactions. This study describes the first rational engineering of MonAzPs biosynthesis and provides a roadmap for future pathway engineering efforts directed towards the selective production of the most valuable pigments and serves as a model for the biosynthesis of fungal azaphilones in general.

Gold Nanoparticles on Mesoporous Interparticle Networks of Titanium Dioxide Nanocrystals for Enhanced Photonic Efficiencies

Abstract: Nanocomposites consisting of Au and TiO2 nanocrystals have been synthesized through simple one-step sol−gel reactions of titanium tetraisopropoxide with hydrogen tetrachloroaurate in the presence of an F127 triblock copolymer as the template to direct the formation of nanostructured photocatalysts. The thus formed Au/TiO2 network gels were calcined at 500 °C for 4 h, leading to Au/TiO2 nanocomposites with high interparticle mesoporosity, pore diameters of around 10 nm, and BET surface areas of about 100 m2/g. TEM investigations of 0.5 wt % Au/TiO2 reveal that the TiO2 particles are quite uniform in size and shape. The particle sizes of TiO2 and Au are in the range of 5−10 and 20−120 nm, respectively. The photocatalytic methanol oxidation to formaldehyde chosen as the test reaction to examine the photocatalytic activity of the Au/TiO2 was shown to be more effective as compared with pure TiO2 and with Degussa P25, respectively. The increased photocatalytic activity of Au/TiO2 with interparticle mesopores is...