High-speed mapping of surface charge dynamics using sparse scanning Kelvin probe force microscopy.

Unraveling local dynamic charge processes is vital for progress in diverse fields, from microelectronics to energy storage. This relies on the ability to map charge carrier motion across multiple length- and timescales and understanding how these processes interact with the inherent material heterogeneities. Towards addressing this challenge, we introduce high-speed sparse scanning Kelvin probe force microscopy, which combines sparse scanning and image reconstruction. This approach is shown to enable sub-second imaging (>3 frames per second) of nanoscale charge dynamics, representing several orders of magnitude improvement over traditional Kelvin probe force microscopy imaging rates. Bridging this improved spatiotemporal resolution with macroscale device measurements, we successfully visualize electrochemically mediated diffusion of mobile surface ions on a LaAlO3/SrTiO3 planar device. Such processes are known to impact band-alignment and charge-transfer dynamics at these heterointerfaces. Furthermore, we monitor the diffusion of oxygen vacancies at the single grain level in polycrystalline TiO2. Through temperature-dependent measurements, we identify a charge diffusion activation energy of 0.18 eV, in good agreement with previously reported values and confirmed by DFT calculations. Together, these findings highlight the effectiveness and versatility of our method in understanding ionic charge carrier motion in microelectronics or nanoscale material systems.

'There is such a thing as too healthy!' The impact of minimum nutritional guidelines on school food practices in secondary schools.

BACKGROUND: Pressure to improve school meals has resulted in stringent nutritional guidelines across the UK. In Wales, the 'Appetite for Life' guidelines of 2008 resulted in significant changes to the provision of food in Welsh schools. Although evaluation of these changes has focussed on nutritional quality, there is little evidence of how pupils perceive these changes and their impact on school food practices. Using a Collective Lifestyles approach, the present study reports how secondary school pupils perceive and negotiate menu changes and the implications for lunchtime practices. METHODS: Seven focus groups (52 pupils) were undertaken in four secondary schools within one local authority in Wales. Participatory techniques were used to facilitate discussion, and the focus groups were recorded, transcribed and analysed using a framework approach. Analysis was underpinned by a Collective Lifestyles approach, which provides a framework to understand behaviour in context using three domains: (i) patterns of consumption; (ii) the construction and maintenance of identity; and (iii) power relationships. RESULTS: Pupils reported that the new menus were unpopular in terms of content and meal type; the preference was for portable and snack style foods. In terms of power relationships, pupils' ability to negotiate within the school setting was constrained by the institutional nature of school dining. As a result, pupils tended to opt out of school food provision, accessing alternatives where possible. CONCLUSIONS: The development of the healthy eating agenda within the school setting needs to consider the complexities of adolescent consumption preferences, identities and social networks if they are to be successful.

Charge-Transport Mechanisms in CuInSe xS2- x Quantum-Dot Films.

Colloidal quantum dots (QDs) have attracted considerable attention as promising materials for solution-processable electronic and optoelectronic devices. Copper indium selenium sulfide (CuInSe xS2- x or CISeS) QDs are particularly attractive as an environmentally benign alternative to the much more extensively studied QDs containing toxic metals such as Cd and Pb. Carrier transport properties of CISeS-QD films, however, are still poorly understood. Here, we aim to elucidate the factors that control charge conductance in CISeS QD solids and, based on this knowledge, develop practical approaches for controlling the polarity of charge transport and carrier mobilities. To this end, we incorporate CISeS QDs into field-effect transistors (FETs) and perform detailed characterization of these devices as a function of the Se/(Se+S) ratio, surface treatment, thermal annealing, and the identity of source and drain electrodes. We observe that as-synthesized CuInSe xS2- x QDs exhibit degenerate p-type transport, likely due to metal vacancies and CuIn'' anti-site defects (Cu1+ on an In3+ site) that act as acceptor states. Moderate-temperature annealing of the films in the presence of indium source and drain electrodes leads to switching of the transport polarity to nondegenerate n-type, which can be attributed to the formation of In-related defects such as InCu•• (an In3+ cation on a Cu1+ site) or Ini••• (interstitial In3+) acting as donors. We observe that the carrier mobilities increase dramatically (by 3 orders of magnitude) with increasing Se/(Se+S) ratio in both n- and p-type devices. To explain this observation, we propose a two-state conductance model, which invokes a high-mobility intrinsic band-edge state and a low-mobility defect-related intragap state. These states are thermally coupled, and their relative occupancies depend on both QD composition and temperature. Our observations suggest that the increase in the relative fraction of Se moves conduction- and valence band edges closer to low-mobility intragap levels. This results in increased relative occupancy of the intrinsic band-edge states and a corresponding growth of the measured mobility. Further improvement in charge-transport characteristics of the CISeS QD samples as well as their stability is obtained by infilling the QD films with amorphous Al2O3 using atomic layer deposition.

Platelet-rich plasma (PRP) enhances bone healing in non-united critical-sized defects: a preliminary study involving rabbit models.

INTRODUCTION: The use of bone grafts in treating non- or delayed unions as the result of large bone loss is well established. However, despite good outcomes, the time to achieve complete union is still considerably long. To overcome this problem, the use of platelet-rich plasma (PRP) has been advocated albeit with varying success. To determine the true effectiveness of PRP in treating non-/delayed unions, a study was conducted using (n=12) rabbit models. METHODS AND MATERIALS: Critical-sized defects measuring 2cm created in the midshaft of the right rabbit tibias were stabilised using 2.7-mm small fragment plates. A spacer placed in the defects to create a delay in bone union was replaced at 3 weeks with artificial bone grafts (Coragraft®), with or without PRP. The operated limbs were radiographed following the defect creation and at 3, 7 and 11 weeks (at sacrifice). Bone healing and histological changes were later assessed and scored using the appropriate grading systems. Four groups were compared for quality of healing: (group-A) control group, that is, no PRP or Coragraft; (group-B) PRP; (group-C) Coragraft; and (group-D) PRP and Coragraft. RESULTS: Group-D demonstrated the best bone healing based on radiological, histological and gross findings (Kruskall-Wallis: p<0.05). Group-C had significantly higher scores than group-B, whilst group-A had significantly lower scores than all other groups (Mann-Whitney U: p<0.05). CONCLUSION: The use of PRP with bone graft significantly improves the quality of bone healing. However, the use of PRP without bone substitute does not provide adequate repair tissue and, therefore, provides little benefit when used independently.

[Lipid aspects in subjects with glucose-6-phosphate dehydrogenase deficiency]. / Il quadro lipidico in soggetti deficienti in glucoso-6-fosfato deidrogenasi.

To control some aspects of Lipid metabolism in G-6-PD defective subjects, are evaluated the haematic levels of Cholesterol, Tri glycerides, total Lipids and Lipoproteins. There is no significative difference between enzymopathic and normal control subjects.