29295 research outputs found
Sort by
Negatively photochromic organic compounds: Exploring the dark side
Full text linkThe last few years have seen an explosion of interest in traditional photochromic systems not only for their applications in variable transmission devices, which continues to attract commercial interest, but also for the ability of these molecules to undergo structural and electronic reorganisation which has been seized upon by materials scientists for the development of switches, logic gates, photoinduced molecular motions such as rotors and fibrils, and photoregulation of drug availability. This comprehensive review examines, for the first time, the ‘dark side of photochromism’; negatively photochromic systems which are coloured in their ground state and reversibly photobleach upon exposure to electromagnetic radiation with a wavelength over ca. 400 nm i.e. visible light responsive systems. This review is organised by structural class and examines their synthesis, structure, key spectroscopic data for coloured and bleached species, structure – switching relationships and applications. The usefulness of these negatively photochromic systems is only gradually coming to the fore with the advantages of low energy activation c.f. conventional Uv-activated switches, enabling the modulation of a plethora of useful optical and physical properties and the design of new materials with broad ranging applications
Collaborative Location Recommendation by Integrating Multi-dimensional Contextual Information
No full textPoint-of-Interest (POI) recommendation is a new type of recommendation task that comes along with the prevalence of location-based social networks and services in recent years. Compared with traditional recommendation tasks, POI recommendation focuses more on making personalized and context-aware recommendations to improve user experience. Traditionally, the most commonly used contextual information includes geographical and social context information. However, the increasing availability of check-in data makes it possible to design more effective location recommendation applications by modeling and integrating comprehensive types of contextual information, especially the temporal information. In this paper, we propose a collaborative filtering method based on Tensor Factorization, a generalization of the Matrix Factorization approach, to model the multi dimensional contextual information. Tensor Factorization naturally extends Matrix Factorization by increasing the dimensionality of concerns, within which the three-dimensional model is the one most popularly used. Our method exploits a high-order tensor to fuse heterogeneous contextual information about users’ check-ins instead of the traditional two dimensional user-location matrix. The factorization of this tensor leads to a more compact model of the data which is naturally suitable for integrating contextual information to make POI recommendations. Based on the model, we further improve the recommendation accuracy by utilizing the internal relations within users and locations to regularize the latent factors. Experimental results on a large real-world dataset demonstrate the effectiveness of our approach
Impact of processing methods on the dissolution of artemether from two non-ordered mesoporous silicas
Full text linkPoor aqueous solubility is often linked with a poor dissolution rate and ultimately, limited bioavailability of pharmaceutical compounds. This study describes the application of mesoporous materials (Syloid 244 and Syloid AL1) in improving the dissolution rate of a drug with poor aqueous solubility, namely artemether, utilising different processing methods including physical mixing, co-grinding and solid dispersions prepared by solvent evaporation and the lyophilisation technique. The prepared formulations were extensively characterised for their solid-state properties and the drug release attributes were studied. Differential scanning calorimetry and X-ray diffraction confirmed conversion of crystalline artemether into a disordered and amorphous form, whilst no intermolecular interactions were detected between artemether and silica. Both silica grades enhanced the dissolution rate of artemether in comparison with drug alone, for example from 17.43% (± 0.87%) to 71.55% (± 3.57%) after 120 mins with lyophilisation and Syloid 244 at a 1:3 ratio. This enhancement was also dependant on the choice of processing method, for example, co-ground and lyophilised formulations prepared with Syloid 244 at 1:3 ratio produced the most extensive dissolution, thus endorsing the importance of materials as well as choice of formulation method
Teacher education, evacuation and community in war-time Britain : The women of Avery Hill at Huddersfield 1941-46
Full text linkThe evacuation of civilians during World War Two Britain included the relocation not only of school children and teachers, but of whole schools and, in some instances, of teacher training colleges. This paper examines the evacuation of Avery Hill College, a leading teacher training college, from London to Huddersfield between 1941 and 1946. Focusing on issues of gender and community, it provides an account of the circumstances of the move, institutional relations and resources, the social milieu of war-time Huddersfield, the challenges arising from evacuation, the responses of staff
and trainees, and the broader institutional and teacher education policy transitions that ensued
Meta-Search Through the Space of Representations and Heuristics on a Problem by Problem Basis
Full text linkTwo key aspects of problem solving are representation and search heuristics. Both theoretical and experimental studies have shown that there is no one best problem representation nor one best search heuristic. Therefore, some recent methods, e.g., portfolios, learn a good combination of problem solvers to be used in a given domain or set of domains. There are even dynamic portfolios that select a particular combination of problem solvers specific to a problem. These approaches: (1) need to perform a learning step; (2) do not usually focus on changing the representation of the input domain/problem; and (3) frequently do not adapt the portfolio to the specific problem. This paper describes a meta-reasoning system that searches through the space of combinations of representations and heuristics to find one suitable for optimally solving the specific problem. We show that this approach can be better than selecting a combination to use for all problems within a domain and is competitive with state of the art optimal planners
The Video Way of Thinking
Full text linkThis article rethinks the concepts of zoê and bios proposed by Giorgio Agamben in relation to the history of technology. It argues that the relationship between embodiment and the audiovisual is only beginning to be understood alongside the recent and increasing omnipresence of digital audiovisual recording technologies in everyday life. Just as writing completely changed human society’s understanding of speech, the development of audiovisual media over the past century has profoundly affected and perhaps even founded our contemporary understanding of embodiment and embodied knowledge. Questions of performance documentation that have circulated in performance studies barely scratch the surface of what amounts to a new way of understanding life, embodiment, and knowledge, which I here begin to call the ‘video way of thinking’
Risk, competition, and efficiency in banking: Evidence from China
Full text linkThis paper tests the interrelationships among risk, competition, and efficiency in the Chinese banking industry between 2003 and 2013, with an efficiency-adjusted Lerner index and stability inefficiency as the indicators of competition and insolvency risk. The results show that Chinese commercial banks with higher efficiency have higher credit risk and insolvency risk, but lower liquidity risk and capital risk. Greater competition decreases credit risk and insolvency risk, but increases liquidity risk. Credit risk and insolvency risk are significantly and positively related to efficiency, while liquidity risk and capital risk are significantly and negatively related. Finally, lower liquidity risk decreases competition
Prospects for Engineering Thermoelectric Properties in La1/3NbO3 Ceramics Revealed via Atomic-Level Characterization and Modeling
Full text linkA combination of experimental and computational techniques has been employed to explore the crystal structure and thermoelectric properties of A-site-deficient perovskite La1/3NbO3 ceramics. Crystallographic data from X-ray and electron diffraction confirmed that the room temperature structure is orthorhombic with Cmmm as a space group. Atomically resolved imaging and analysis showed that there are two distinct A sites: one is occupied with La and vacancies, and the second site is fully unoccupied. The diffuse superstructure reflections observed through diffraction techniques are shown to originate from La vacancy ordering. La1/3NbO3 ceramics sintered in air showed promising high-temperature thermoelectric properties with a high Seebeck coefficient of S1 = −650 to −700 μV/K and a low and temperature-stable thermal conductivity of k = 2–2.2 W/m·K in the temperature range of 300–1000 K. First-principles electronic structure calculations are used to link the temperature dependence of the Seebeck coefficient measured experimentally to the evolution of the density of states with temperature and indicate possible avenues for further optimization through electron doping and control of the A-site occupancies. Moreover, lattice thermal conductivity calculations give insights into the dependence of the thermal conductivity on specific crystallographic directions of the material, which could be exploited via nanostructuring to create high-efficiency compound thermoelectrics
Access Repository Dashboard
Do you manage University of Huddersfield Repository? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!