Chromium Oxide Formation on Nanosecond and Femtosecond Laser Irradiated Thin Chromium Films

Thin coatings of Chromium oxide have been used for applications as absorbing material in solar cells, as protections for magnetic data recording devices and as shields in flexible solar cells. Thin coatings of pure chromium were vacuum deposited on a glass substrate using hot electrons from tungsten filament. These coatings were then treated with a nanosecond and femtosecond laser in ambient conditions. The microstructure, morphology and the color of the coatings treated with laser sources were modified and there was a formation of an oxide layer due to the heat dissipation on the chromium coating from the energetic photons. High-resolution scanning electron microscope studies showed the morphological evolution that are directly correlated with the laser fluence of both the nanosecond and femtosecond lasers. This morphological evolution was accompanied by the microstructural change as observed from the x-ray diffraction patterns, the chromaticity response of the coating was studied by UV-Vis spectrometer and the response of the coating in the visible region evolved with the laser fluences. The Rutherford backscattering depth profiling of the laser treated coatings revealed the diffusion of oxygen atoms in the coating as a result of laser treatment fluence

Towards Room Temperature Thermochromic Coatings with controllable NIR-IR modulation for solar heat management & smart windows applications

Solar heat management & green air-conditioning are among the major technologies that could mitigate heat islands phenomenon while minimizing significantly the CO2 global foot-print within the building & automotive sectors. Chromogenic materials in general, and thermochromic smart coatings especially are promising candidates that consent a noteworthy dynamic solar radiation Infrared (NIR-IR) regulation and hence an efficient solar heat management especially with the expected increase of the global seasonal temperature. Within this contribution, two major challenging bottlenecks in vanadium oxide based smart coatings were addressed. It is validated for the first time that the NIR-IR modulation of the optical transmission (∆TTRANS = T(T〈TMIT) − T(T〉TMIT) of Vanadium oxide based smart coatings can be controlled & tuned. This upmost challenging bottle-neck controllability/tunability is confirmed via a genuine approach alongside to a simultaneous drastic reduction of the phase transition temperature TMIT from 68.8 °C to nearly room temperature. More precisely, a substantial thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of standard pure VO2 thin films but with a far lower transition temperature, is reported. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control & tunability of the optical transmission modulation in the NIR-IR (∆TTRANS) via the nano-scaled thickness’ control of the intermediate Vanadium layer. In addition, the control of ∆TTRANS is accompanied by a tremendous diminution of the thermochromic transition temperature from the elevated bulk value of 68.8 °C to the range of 27.5–37.5 ºC. The observed remarkable and reversible thermochromism in such multilayered nano-scaled system of V2O5/V/V2O5 is likely to be ascribed to a noteworthy interfacial diffusion, and an indirect doping by alkaline ions diffusing from the borosilicate substrate. It is hoped that the current findings would contribute in advancing thermochromic smart window technology and their applications for solar heat management in glass windows in general, skyscraper especially & in the automotive industry. If so, this would open a path to a sustainable green air-conditioning with zero-energy input

Social learning in LEADER: Exogenous, endogenous and hybrid evaluation in rural development

This paper considers the relationship between the centralised exogenous, institutions and the embedded, endogenous institutions of rural governance in Europe through an examination the evaluation procedures of the European LEADER programme. LEADER is presented in the literature as progressive in terms of innovation and stakeholder engagement. Yet while the planning and management of LEADER embraces heterogeneity and participation, programmatic evaluation is centralised and held at arms length from delivery organisations. The paper reviews previous efforts to improve evaluation in LEADER and considers alternative strategies for evaluation, contrasting LEADER practice with participatory evaluation methodologies in the wider international context. Can evaluation in itself be valuable as a mode of social learning and hence a driver for endogenous development in rural communities in Europe? The paper concludes by examining the challenges in producing a hybrid form of evaluation which accommodates endogenous and exogenous values

Fat, fibre and cancer risk in African Americans and rural Africans

Rates of colon cancer are much higher in African Americans (65: 100,000) than in rural South Africans (Peer reviewe

Fat, fibre and cancer risk in African Americans and rural Africans

Rates of colon cancer are much higher in African Americans (65: 100,000) than in rural South Africans (Peer reviewe

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Chromium oxide formation on nanosecond and femtosecond laser irradiated thin chromium films

Thin coatings of Cr2O3 have been used for numerous applications. Selective oxidation of chromium will be beneficial for integrated device fabrications. Thin coatings of pure chromium were vacuum deposited on a glass substrate using hot electrons from tungsten filament. These coatings were then treated with nanosecond and femtosecond laser in ambient conditions. The microstructure, morphology and the color of the coatings treated with laser sources were modified and there was a formation of an oxide layer due to the heat dissipation on the chromium coating from the energetic photons. High-resolution scanning electron microscope studies showed the morphological evolution, which is directly correlated with the laser fluence of both the nanosecond and femtosecond lasers. This morphological evolution was accompanied by the microstructural change as observed from the X-ray diffraction patterns. The chromaticity response of the coating was studied by UV–Vis spectroscopy and the response of the coating in the visible region evolved with the laser fluences. The divergence in chromaticity of these two laser treatments, is due to the difference in morphology as the result of the varied pulse duration. It could be concluded that the morphology had effect on the chromaticity of the films. Futhermore, Rutherford backscattering depth profiling of the laser treated coatings revealed the diffusion of oxygen atoms in the coating as a result of laser treatment fluence. We have analyzed both the optical and material properties of the laser induced oxidation and demonstrated laser writing as a promising tool to selectively oxidize Chromium for integrated device applications

Inter-examiner reliability when using the Objective Structured Practical Examination (OSPE) mark sheet for physiotherapy practical

The Objective Structured Practical Examination (OSPE) format is used during practical examinations as part of the physiotherapy undergraduate curriculum at the University of the Witwatersrand. Various factors influence inter-examiner reliability and investigating the inter-examiner reliability when using the OSPE can lead to improvement of the examination process. The aim of this study was to establish inter-examiner reliability when using the OSPE mark sheet. Methods: Twelve examiners participated in this study. Thirty-three second year PT students were examined at six stations and by two examiners at each station. The Spearman’s correlation test was used to establish inter-examiner reliability. Results: The general inter-examiner reliability of the OSPE mark sheet was high. There was a high correlation between examiners who had the same level of experience (r=0.79 to r=0.93; p<0.001). The background knowledge section of the OSPE mark sheet showed the greatest inter-examiner reliability (r=0.75 to r=0.91; p<0.001). Discussion: In general, a high inter-examiner reliability was found. Examiners with the same level of experience seemed to generally have better inter-examiner reliability when using the OSPE mark sheet. Furthermore, a well-described, operationalised list of micro-skills also improved inter-examiner reliability. Conclusion: The OSPE mark sheet aids inter-examiner reliability. The use of this method of examination should be encouraged

The implementation of the Objective Structured Practical Examination (OSPE) method: Students’ and examiners’ experiences

Background. Traditionally, physiotherapy practical skills have been assessed by a method that relies on the subjective interpretation of competency by the examiner and lacks the formative benefits of  assessment.Objective. To describe and compare student performance and satisfaction and examiner satisfaction  with regard to the Objective Structured Practical Examination (OSPE) and traditional mark sheets during the practical skills assessment.Method. Students and examiners taking part in the second-year physiotherapy practical skills test were invited to participate by completing a series of questionnaires. Performance of techniques was marked using both the OSPE and traditional mark sheets.Results. Sixty-seven students and nine examiners participated in the study. Students scored an average of 4.6% (SD ±16.4) better when using the traditional mark sheet. Nonetheless, students and examiners expressed a preference for the OSPE mark sheet.Conclusion. The OSPE mark sheet allows for increased objectivity, as the specific micro-skills are clearly  listed and appropriately weighted. This resulted in increased satisfaction, but a decrease in marks obtained. By assessing the effect of implementation of the OSPE method on performance and satisfaction, change in the current situation can be monitored