Characterization of the novel ene reductase Ppo-Er1 from paenibacillus polymyxa

Ene reductases enable the asymmetric hydrogenation of activated alkenes allowing the manufacture of valuable chiral products. The enzymes complement existing metal- and organocatalytic approaches for the stereoselective reduction of activated C=C double bonds, and efforts to expand the biocatalytic toolbox with additional ene reductases are of high academic and industrial interest. Here, we present the characterization of a novel ene reductase from Paenibacillus polymyxa, named Ppo-Er1, belonging to the recently identified subgroup III of the old yellow enzyme family. The determination of substrate scope, solvent stability, temperature, and pH range of Ppo-Er1 is one of the first examples of a detailed biophysical characterization of a subgroup III enzyme. Notably, Ppo-Er1 possesses a wide temperature optimum (Topt: 20–45 °C) and retains high conversion rates of at least 70% even at 10 °C reaction temperature making it an interesting biocatalyst for the conversion of temperature-labile substrates. When assaying a set of different organic solvents to determine Ppo-Er1′s solvent tolerance, the ene reductase exhibited good performance in up to 40% cyclohexane as well as 20 vol% DMSO and ethanol. In summary, Ppo-Er1 exhibited activity for thirteen out of the nineteen investigated compounds, for ten of which Michaelis–Menten kinetics could be determined. The enzyme exhibited the highest specificity constant for maleimide with a kcat/KM value of 287 mM−1 s−1. In addition, Ppo-Er1 proved to be highly enantioselective for selected substrates with measured enantiomeric excess values of 92% or higher for 2-methyl-2-cyclohexenone, citral, and carvone

Nonlocal and collective phenomena in the plasmons of metallic nanostructures: With application to ultrasensitive biosensing and nonlinear nano-optics

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 10-03-201

Beyond classical electrodynamics: mesoscale electron dynamics and nonlinear effects in hybrid nanostructured systems

This work investigates the optial properties of hybrid metal-dielectric and ionic-solid largely regular nanostructures in the presence of nanosized features such as gaps and thin walls in tubular structures. The fundamental optical response of plasmonic, ionic and dielectric systems is considered from a classical electromagnetic perspective, including properties of amorphous materials, rough interfaces, nonlinear and semi-classical charge interactions. We focus hereby on two aspects: (i) nonclassical effects stemming from the quantum nature of freely moving charges and (ii) nonlinear optical response. The overall aim is to realistically describe complex nanoparticle distributions and ultrathin multilayers with reliable and rapid methods of computational nanophotonics while extending its scope towards multiphysics aspects beyond classical electrodynamics. The analytical and numerical models developed over the past years are presented in this work in detail with standard, but necessary technical details available in the appendices. We often assume a multilayered system where one layer is a nanostructure with either one- or two-dimensional symmetry, i.e., a grating or laminar structure in the first and an array of nanoparticles (disks, holes, pillars, etc.) in the latter case. Given the symmetries and overall composition of the structure, our method of choice is the Fourier Modal Method (FMM) together with the scattering matrix approach to connect the different layers. The standard FMM formulation is extended to include spatial dispersion effects of conduction band electrons in metals introducing not only an additional boundary condition, but an overall third longitudinal solution to the standard transversal solutions of the electromagnetic wave equation. Furthermore, we explore the impact of higher harmonic waves, in particular second and third harmonic generation, from the local fields around the nanostructures studied

The quality of details when children and youths with intellectual disabilities are interviewed about their abuse experiences

The question for this study was to further understand how children and youths with intellectual disabilities (IDs) provide central and peripheral details when interviewed about their abuse experiences. Through a quantitative method we examined police officers' first formal investigative interviews with 32 children and youths with IDs. We analyzed the details they reported about abuse in relation to types of questions asked. The findings showed that few open-ended invitations were used and that a large number of option-posing questions were asked. The children and youths tended to agree with option-posing and suggestive statements but were nonetheless able to report important information about their abuse experiences without the ‘help’ from these potentially contaminating questions. The results of this study are limited because of the selective nature of the sample and that we did not have access to complete information about the participants specific diagnosis. Although it shows that police officers need to provide children and youths with IDs greater opportunities to report details using open-ended invitations. If they do not develop their responses when asked open-ended invitations they may be asked open directive questions to facilitate the elicitation of both central and peripheral information

Thin Films of Nonlinear Metallic Amorphous Composites

We studied the nonlinear optical response of metallic amorphous composite layers in terms of a self-phase-modulated, third-order Kerr nonlinearity. A nonlinear effective medium theory was used to describe low densities of gold and iridium nanoparticles embedded in an equally nonlinear host material. The fill fraction strongly influences the effective nonlinear susceptibility of the materials, increasing it by orders of magnitude in the case of gold due to localized surface plasmonic resonances. The enhancement of the nonlinear strength in amorphous composites with respect to the bulk material has an upper limit in metallic composites as dominating absorption effects take over at higher fill factors. Both saturated and induced absorption in the thin films of amorphous composites were observed depending on the selected frequency and relative position to the resonant frequency of electron excitation in the metallic inclusions. We demonstrated the depths to which thin films are affected by nonlinear enhancement effects

Spatial dispersion in two-dimensional plasmonic crystals: Large blueshifts promoted by diffraction anomalies

We develop a methodology to incorporate nonlocal optical response of the free electron gas due to quantum-interaction effects in metal components of periodic two-dimensional plasmonic crystals and study the impact of spatial dispersion on promising building blocks for photonic circuits. Within the framework of the hydrodynamic model, we observe significant changes with respect to the commonly employed local-response approximation, but also in comparison with homogeneous metal films where nonlocal effects have previously been considered. Notable are the emergence of a contribution from nonlocality at normal incidence and the surprisingly large structural parameters at which finite blueshifts are observable, which we attribute to diffraction that offers nonvanishing in-plane wave vector components and increases the penetration depth of longitudinal (nonlocal) modes.We acknowledge Sanshui Xiao for fruitful discussions. C. D. thanks the Deutsche Forschungsgemeinschaft (German Research Foundation) for financial support through a DFG research fellowship (No. 268910011) .J.C. acknowledges financial support from the Danish Council for Independent Research and a Sapere Aude Grant (FTP No. 12-134776). N.A.M. acknowledges support from the Danish Council for Independent Research (FNU No. 1323-00087). The Center for Nanostructured Graphene is sponsored by the Danish National Research Foundation, Project No. DNRF103

Chapter Introducing Asian Sound Cultures

In this brief introduction we highlight the importance of broadening the cartography of sound studies beyond the West. Over the last decade or so, the geographical range of sound studies has rapidly broadened at the same time as keywords and approaches to sound in the humanities and social sciences have become increasingly standardised theoretical and conceptual tools. The need to explore ways of thinking about sound articulated by experiences outside the West is becoming essential to ensuring the field remains as open to interpretation and as diffuse in nature and geography as the object of study itself. In this introduction we outline the contributions to this project made by the chapters gathered in this volume. We argue that mixing historical perspectives with ethnography, literary studies, film studies, technology, language and music and listening for the inflections driven by sonic regimes imposed by a global process of change in Asia can help us to better understand the shared experience and construction of modern sound. We also argue for an ‘international localism’ that, whilst accepting that the sound of modernity is inseparable from the process of modernity, amplifies the ambiguity of modern understandings of sound and mobilises the diverse historical experiences and rich social practices of Asia to provide alternative horizons for the exciting and vibrant field of sound studies

A combined NMR crystallographic and PXRD investigation of the structure-directing role of water molecules in orotic acid and its lithium and magnesium salts

Despite the abundance of hydrates, their multifaceted nature and hydration/dehydration behaviour is still not fully understood. For the example of orotic acid monohydrate and its lithium and magnesium hydrate salts, we show how NMR crystallography, namely a combination of solid-state NMR with a focus here on 1H Magic Angle Spinning (MAS) NMR experiments and first-principles DFT GIPAW (gauge-including projector augmented wave) calculations, can play a valuable role in the characterization of hydrate systems. Starting from lithium orotate monohydrate, a rigid system with a limited number of tightly bound water molecules, the general feasibility of this approach was demonstrated. Moving onto more complex hydrate structures, mobility in the orotic acid monohydrate was observed, while for the most complex hydrate, magnesium orotate octahydrate, a loss of associated water molecules was observed after an overnight MAS NMR experiment. A combined study by experimental MAS NMR, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) revealed changes after vacuum drying as well as after storage of a vacuum dried sample under ambient conditions. Specifically, TGA showed the vacuum dried sample to correspond to a dihydrate, for which no structure has yet been determined by single-crystal diffraction. An NMR crystallography analysis showed that a combination of putative symmetric and asymmetric dihydrate structures explains the observed changes in the experimental MAS NMR spectra