90 research outputs found
Collective Hydrogen Bonding between Amides Enhances the Basicity of Their Clustered Form in the Proton Transfer of a Super Photoacid
School of Molecular Sciences(Chemistry)The excited state proton transfer (ESPT) of the strong photoacid N-methyl-7-hydroxyquinolium (NM7HQ) was studied in the presence of N-methylbenzamide (NMB) as a base in the aprotic solvent of acetonitrile. In the ground state, it is found that the complexed form of NM7HQ and NMB exists with a 1:1 ratio with the association constant (K) to 22.2 ?? 1.7 M-1, obtained by using the Benesi-Hilderbrand relation. Also, the cationic photoacid fluorescence lifetime Stern-Volmer relation of fast decay time shows that the ESPT of NM7HQ and NMB has the molecularity of two with amides. Therefore, in the excited state, one more molecule of NMB is needed to the ground state NM7HQ-NMB complex for ESPT. It shows that the hydrogen bonded complex of 2 molecules of NMB can enhance the basicity of the NMB molecule.ope
Anglo-American relations and the attempts to settle the Korean question 1953-1960.
This study examines the nature of Anglo-American relations in their dealings with Korea between 1953 and 1960. It assesses the different attitudes and approaches of the two governments over the conduct of the Korean phase of the Cold War. The truce negotiations, the political conference in Geneva, the discussions at the United Nations and the issues of troop withdrawal and economic aid are examined. Debates over these issues created a certain degree of tension in the US-UK relationship but it was not as acute as it might have been. The thesis explains why and how the US and UK tried to avoid confrontation and cooperate in seeking a peaceful solution to the Korean question. At Panmunjom, Britain was disappointed by the American hardline position, but accepted the stalemate with the Communists. The Korean phase of the East-West struggle continued in Geneva: the British mediation which was highlighted by Eden's compromise proposals, satisfied neither the US-ROK nor the Communists. The US was determined to dictate the conduct of the peace process but experienced increasing difficulties in maintaining their Cold War strategy. The US had to retain control over the ROK without alienating the Western Allies. The difficulty in reconciling the positions of the ROK with its allies led the US to decide to insist on the status quo of a divided Korea. The US maintained this position and prevented the ninth UN General Assembly reopening the Korean question, for they were not prepared to risk upsetting the status quo. The British wished to end their military commitment when the strategic and financial considerations outweighed any meagre political influence over the Americans. Britain, nevertheless, was always ready not to allow Anglo-American solidarity to be undermined by disputes over Korea. Britain's overwhelming interests lay in the prospect of cementing the 'special relationship'. In examining British and American attempts to deal with these issues this study will contribute to the understanding of an important aspect of Anglo-American relations at the height of the Cold War in East Asia
Object detection algorithm for unmanned surface vehicle using faster R-CNN
The purpose of this research is development of vision-based object detection algorithm that recognizes a marine object, localizes the object on captured frames, and estimates the distance to the object. Faster R-CNN and stereo vision based depth estimation are combined for real-time marine object detection. The performance of this algorithm is verified by model ship detection test in towing tank. The test results showed that this algorithm is potentially applicable to real USV
Synergistic growth of nickel and platinum nanoparticles via exsolution and surface reaction
Funding; EPSRC for a Critical Mass project EP/R023522/1 and Electron Microscopy provision EP/R023751/1, EP/L017008/1.Bimetallic catalysts combining precious and earth-abundant metals in well designed nanoparticle architectures can enable cost efļ¬cient and stable heterogeneous catalysis. Here, we present an interaction-driven in-situ approach to engineer ļ¬nely dispersed Ni decorated Pt nanoparticles (1-6 nm) on perovskite nanoļ¬bres via reduction at high temperatures (600-800oC). Deposition of Pt (0.5 wt%) enhances the reducibility of the perovskite support and promotes the nucleation of Ni cations via metal-support interaction, thereafter the Ni species react with Pt forming alloy nanoparticles, with the combined processes yielding smaller nanoparticles that either of the contributing processes. Tuneable uniform Pt-Ni nanoparticles are produced on the perovskite surface, yielding reactivity and stability surpassing 1 wt.% Pt/Ī³-Al2O3 catalysts for CO oxidation. This approach heralds the possibility of in-situ fabrication of supported bimetallic nanoparticles with engineered compositional distributions and performance.Peer reviewe
Phenotype and genetic analysis of data collected within the first year of NeuroDev
Genetic association studies have made significant contributions to our understanding of the etiology of neurodevelopmental disorders (NDDs). However, these studies rarely focused on the African continent. The NeuroDev Project aims to address this diversity gap through detailed phenotypic and genetic characterization of children with NDDs from Kenya and South Africa. We present results from NeuroDevās first year of data collection, including phenotype data from 206 cases and clinical genetic analyses of 99 parent-child trios. Most cases met criteria for global developmental delay/intellectual disability (GDD/ID, 80.3%). Approximately half of the children with GDD/ID also met criteria for autism. Analysis of exome-sequencing data identified a pathogenic or likely pathogenic variant in 13 (17%) of the 75 cases from South Africa and 9 (38%) of the 24 cases from Kenya. Data from the trio pilot are publicly available, and the NeuroDev Project will continue to develop resources for the global genetics community
Oscillation of a small HĪ± surge in a solar polar coronal hole
HĪ± surges (i.e. cool/dense collimated plasma ejections) may act as a guide for a propagation of magnetohydrodynamic waves. We report a high-resolution observation of a surge observed with 1.6 m Goode Solar Telescope (GST) on 2009 August 26, from 18:20 UT to 18:45 UT. Characteristics of plasma motions in the surge are determined with the normalizing radial gradient filter and the Fourier motion filter. The shape of the surge is found to change from a āCā shape to an inverse āCā shape after a formation of a cusp, a signature of reconnection. There are apparent upflows seen above the cusp top and downflows below it. The upflows show rising and rotational motions in the right-hand direction, with the rotational speed decreasing with height. Near the cusp top, we find a transverse oscillation of the surge, with the period ofā¼2 min. There is no change of the oscillation phase below the cusp top, but above the top a phase change is identified, giving a vertical phase speed about 86 km sā1. As the height increases, the initial amplitude of the oscillation increases, and the oscillation damping time decreases from 5.13 to 1.18 min. We conclude that the oscillation is a propagating kink wave that is possibly excited by the repetitive spontaneous magnetic reconnection
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