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Warrington, United Kingdom

Daresbury Laboratory is a scientific research laboratory near Daresbury in Cheshire, England, which began operations in 1962 and was officially opened on 16 June 1967 as the Daresbury Nuclear Physics Laboratory by the then Prime Minister of United Kingdom, Harold Wilson. It is run by the Science and Technology Facilities Council with around three hundred full-time staff. Wikipedia.

Tomic S.,Daresbury Laboratory
Physical Review B - Condensed Matter and Materials Physics

We present a theoretical model for design and analysis of semiconductor quantum dot (QD) array-based intermediate-band solar cell (IBSC). The plane-wave method with periodic boundary conditions is used in expansion of the k·p Hamiltonian for calculation of the electronic and optical structures of InAs/GaAs QD array. Taking into account realistic QD shape, QD periodicity in the array, as well as effects such as band mixing between states in the conduction and valence band, strain and piezoelectric field, the model reveals the origin of the intermediate-band formation inside forbidden energy gap of the barrier material. Having established the interrelation between QD periodicity and the electronic structure across the QD array Brillouin zone, conditions are identified for the appearance of pure zero density-of-states regions, that separate intermediate band from the rest of the conduction band. For one realistic QD array we have estimated all important absorption coefficients in IBSC, and most important, radiative and nonradiative scattering times. Under radiative-limit approximation we have estimated efficiency of such IBSC to be 39%. © 2010 The American Physical Society. Source

Pereira Jr. M.F.,Sheffield Hallam University | Tomic S.,Daresbury Laboratory
Applied Physics Letters

We investigate the possibility of interconduction band gain without global inversion by engineering the conduction band effective masses so that the upper lasing subband has an effective mass considerably smaller than the lower lasing subband that could not be obtained in conventional III-V materials. We recover the expected dispersive gain shape for similar masses and contrasting results if the effective masses characterizing the relevant subbands are very different. © 2011 American Institute of Physics. Source

Metz S.,Daresbury Laboratory | Thiel W.,Max-Planck-Institut fur Kohlenforschung
Coordination Chemistry Reviews

In recent years, advances in theoretical methods and computational capabilities have made it possible to investigate reaction mechanisms in enzymes. Density functional theory (DFT) is commonly used to study reactions in model systems, while combined quantum mechanical/molecular mechanical (QM/MM) approaches allow the treatment of the complete solvated enzyme and thus provide insight into the mechanistic influence of the protein environment. This review starts with a brief overview over the available DFT and QM/MM methodology and then summarizes recent theoretical studies on biocatalysis by molybdenum-containing enzymes. It focuses on the reactions in members of the dimethylsulfoxide reductase, sulfite oxidase, and xanthine oxidase families, with special emphasis on the QM/MM studies of the latter. It concludes with a brief survey of theoretical work on some other molybdenum- and tungsten-containing enzymes. © 2011 Elsevier B.V. Source

Winter G.,Diamond Light Source | Winter G.,Daresbury Laboratory | Winter G.,University of Manchester
Journal of Applied Crystallography

An expert system for macromolecular crystallography data reduction is presented, which builds on existing software to automate the complete data reduction process from images to merged structure factor amplitudes. This can automatically identify multi-wedge, multi-pass and multiwavelength data sets and includes explicit procedures to test for crystallographic special cases. With the push towards high-thoughput crystallography at synchrotron beamlines and automation of structure solution, the ability to reduce data with no user input fills an important gap in the pipeline. © 2010 International Union of Crystallography Printed in Singapore-all rights reserved. Source

Morris C.,Daresbury Laboratory
Acta Crystallographica Section D: Biological Crystallography

This is an introduction to four papers based on presentations given at a workshop entitled Integrated Software for Integrative Structural Biology. The use of hybrid techniques, and other trends in structural research, pose new challenges to software developers. A structural biology work bench that meets these needs would provide seamless data transfer between processing steps, and accumulate archival data and metadata without intruding into the scientist's work process. © 2013 International Union of Crystallography Printed in Singapore - all rights reserved. Source

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