Structure determination from powder data : Mogul and CASTEP

When solving the crystal structure of complex molecules from powder data, accurately locating the global minimum can be challenging, particularly where the number of internal degrees of freedom is large. The program Mogul provides a convenient means to access typical torsion angle ranges for fragments related to the molecule of interest. The impact that the application of modal torsion angle constraints has on the structure determination process of two structure solution attempts using DASH is presented. Once solved, accurate refinement of a molecular structure against powder data can also present challenges. Geometry optimisation using density functional theory in CASTEP is shown to be an effective means to locate hydrogen atom positions reliably and return a more accurate description of molecular conformation and intermolecular interactions than global optimisation and Rietveld refinement alone

GDASH: a grid-enabled program for structure solution from powder diffraction data

The simulated annealing approach to structure solution from powder diffraction data, as implemented in the DASH program, is easily amenable to parallelization at the individual run level. Very large scale increases in speed of execution can therefore be achieved by distributing individual DASH runs over a network of computers. The GDASH program achieves this by packaging DASH in a form that enables it to run under the Univa UD Grid MP system, which harnesses networks of existing computing resources to perform calculations

MDASH: a multi-core-enabled program for structure solution from powder diffraction data

The simulated annealing approach to structure solution from powder diffraction data, as implemented in the DASH program, is easily amenable to parallelization at the individual run level. Modest increases in speed of execution can therefore be achieved by executing individual DASH runs on the individual cores of CPUs

How signature strengths develop positive interdependence and empowerment in an inclusive education context

This study evaluates the Individual Strengths, Collective Power! program in fostering students' use of strengths vocabulary and improving classroom relationships in an inclusive education setting in Switzerland, where students with and without special educational needs and disabilities (SEND) attend school together. The study involved 179 students, ages 8 to 12, divided into an experimental group that received specific training and an active control group that had access to program resources, regardless of their SEND status. The study used the Strengths Use Scale (SUS) and the Gratitude Questionnaire to measure students' awareness of their strengths and gratitude. In addition, a sociometric measure, the Peer Acceptance Index (PAI), was developed to assess classroom dynamics. Results indicate that strengths-based interventions significantly expanded students' vocabulary of strengths and increased positive discourse, particularly among girls. Time and age were the main predictors of positive peer commentary, rather than the interventions themselves, which had no significant effect on PAI scores. The study suggests that strengths-based tools, even without guided use, can positively influence students' language about strengths, although they did not change classroom relationships within the 9-week period. Further research is recommended to explore the specific effects and mechanisms of strengths-based interventions in inclusive settings

Strain-induced kinetics of intergrain defects as the mechanism of slow dynamics in the nonlinear resonant response of humid sandstone bars

A closed-form description is proposed to explain nonlinear and slow dynamics effects exhibited by sandstone bars in longitudinal resonance experiments. Along with the fast subsystem of longitudinal nonlinear displacements we examine the strain-dependent slow subsystem of broken intergrain and interlamina cohesive bonds. We show that even the simplest but phenomenologically correct modelling of their mutual feedback elucidates the main experimental findings typical for forced longitudinal oscillations of sandstone bars, namely, (i) hysteretic behavior of a resonance curve on both its up- and down-slopes, (ii) linear softening of resonant frequency with increase of driving level, and (iii) gradual recovery (increase) of resonant frequency at low dynamical strains after the sample was conditioned by high strains. In order to reproduce the highly nonlinear elastic features of sandstone grained structure a realistic non-perturbative form of strain potential energy was adopted. In our theory slow dynamics associated with the experimentally observed memory of peak strain history is attributed to strain-induced kinetic changes in concentration of ruptured inter-grain and inter-lamina cohesive bonds causing a net hysteretic effect on the elastic Young's modulus. Finally, we explain how enhancement of hysteretic phenomena originates from an increase in equilibrium concentration of ruptured cohesive bonds that are due to water saturation.Comment: 5 pages, 3 figure

Detection of nitroaromatic vapours with diketopyrrolopyrrole thin films exploring the role of structural order and morphology on thin film properties and fluorescence quenching efficiency

This document is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. The Version of Record is available at: https://doi.org/10.1039/C4CC08468C.Sensitive optical detection of nitroaromatic vapours with diketopyrrolopyrrole thin films is reported for the first time and the impact of thin film crystal structure and morphology on fluorescence quenching behaviour demonstratedPeer reviewedFinal Accepted Versio

Synthesis and antiviral properties of spirocyclic [1,2,3]-triazolooxazine nucleosides

An efficient synthesis of spirocyclic triazolooxazine nucleosides is described. This was achieved by the conversion of β-D-psicofuranose to the corresponding azido-derivative, followed by alkylation of the primary alcohol with a range of propargyl bromides - obtained via Sonogashira chemistry. The products of these reactions underwent 1,3-dipolar addition smoothly to generate the protected spirocyclic adducts. These were easily deprotected to give the corresponding ribose nucleosides. The library of compounds obtained was investigated for its antiviral activity, using MHV (Mouse Hepatitis Virus) as a model wherein derivative 3f showed the most promising activity and tolerability

Synthesis and antiviral activity of novel spirocyclic nucleosides

The synthesis of a number of spirocyclic ribonucleosides containing either a triazolic or azetidinic system is described, along with two analogous phosphonate derivatives of the former. These systems were constructed from the same β-D-psicofuranose starting material. The triazole spirocyclic nucleosides were constructed using the 1-azido-1-hydroxymethyl derived sugars, where the primary alcohol was alkylated with a range of propargyl bromides, whereas the azetidine systems orginated from the corresponding 1-cyano-1-hydroxymethyl sugars. Owing to their close similarity with ribavirin, the library of compounds were investigated for their antiviral properties using MHV (Murine Hepatitis Virus) as a model