58 research outputs found

    Research and development of CuInSe[2]-based photovoltaic solar cells.

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    The work reported in this thesis includes the growth and characterisation of CuInSe[2]-based materials as well as the assessment and development of CuInSe[2]-based solar cells by the technique of electrodeposition.Cu(InGa)(SeS)[2] layers grown on glass/molybdenum by the two-stage method at Showa Shell have been used for comparison.Electrodeposition of window materials (ZnSe and CdS) on glass/TCO substrates following the conditions prior-established at Sheffield Hallam University has been achieved. CuInSe[2] films have been successfully grown on glass/TCO by electrodeposition. The semi-conducting layers were characterised to investigate their crystallinity, morphology, composition, optical and electrical properties. The structure of the films was characterised by XRD and Raman spectroscopy. The morphology was studied by SEM and AFM. The elemental bulk analysis was performed using XRF and ICPMS. The elemental surface analysis was performed using XPS and the depth profile analysis was studied by GDOES. The optical properties were characterised by optical absorption and the conductivity type was determined by PEC measurements. The conditions of electrodeposition and post deposition treatments were found to influence strongly the properties of the electrodeposited films. Near-stoichiometric films grown by electrodeposition are polycrystalline with a (112) preferential orientation of the chalcopyrite structure. CIS films appear dense with a good mechanical adhesion to the conducting oxide substrates and show crack-free surfaces with spherical grains electrically well connected to each other with a size up to 1 um. Cu, In and Se atoms are not uniformly distributed within the CIS films and In-rich phases, such as CuIn3Se5, cover the surface of the films. Testing of electrical conductivity shows that the films are generally p-type.I-V and C-V measurements were used to characterise the solar cells based on electrodeposited CuInSe[2]. Early stage CuInSe[2]-based solar cells showed encouraging results with efficiencies up to 15.9 % for the best devices. The maximum values of the V[oc], J[sc] and FF observed for the glass/FTO/ZnSe/CuInSe[2]/Au devices were 0.3 V, 105.0 mA/cm[2], and 50 %, respectively

    Iron Thin Films from Fe„CO…5 and FeCp2/H2O under Atmospheric Pressure

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    Iron layers were first obtained from iron pentacarbonyl in metallorganic chemical vapor deposition MOCVD process under atmospheric pressure, in the temperature range 473–773 K, in a vertical cold wall reactor. Films of good purity were obtained with or without hydrogen as co-reactant, no chemical additives being used. The experiments showed that the velocity of the gas stream and, to a lower extent, the precursor molar fraction are the key parameters to be controlled, in order to monitor film growth rate and purity. In a second step, Fe thin layers were obtained by atmospheric pressure MOCVD starting from the reactive gas mixture FeCp2 and H2O in the temperature range 973–1073 K. A thermochemical simulation of the Fe-C-H-O system allowed optimum processing conditions to be approached. X-ray diffraction and microprobe analysis showed that the highest iron content in the layer was obtained for H2O/FeCp2 ratios between 4 and 6. Film growth occurs in two steps: the initial formation of a black, powdered, and porous layer that becomes densified as a result of the grain growth on increasing the deposition time in order to form compact gray metal films. This two-step mechanism was confirmed by kinetic and in situ IR pyrometric observations

    Fitness of Escherichia coli strains carrying expressed and partially silent IncN and IncP1 plasmids

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    BACKGROUND: Understanding the survival of resistance plasmids in the absence of selective pressure for the antibiotic resistance genes they carry is important for assessing the value of interventions to combat resistant bacteria. Here, several poorly explored questions regarding the fitness impact of IncP1 and IncN broad host range plasmids on their bacterial hosts are examined; namely, whether related plasmids have similar fitness impacts, whether this varies according to host genetic background, and what effect antimicrobial resistance gene silencing has on fitness. RESULTS: For the IncP1 group pairwise in vitro growth competition demonstrated that the fitness cost of plasmid RP1 depends on the host strain. For the IncN group, plasmids R46 and N3 whose sequence is presented for the first time conferred remarkably different fitness costs despite sharing closely related backbone structures, implicating the accessory genes in fitness. Silencing of antimicrobial resistance genes was found to be beneficial for host fitness with RP1 but not for IncN plasmid pVE46. CONCLUSIONS: These findings suggest that the fitness impact of a given plasmid on its host cannot be inferred from results obtained with other host-plasmid combinations, even if these are closely related

    Inhibition of Rac controls NPM–ALK-dependent lymphoma development and dissemination

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    Nucleophosmin-anaplastic lymphoma kinase (NPM–ALK) is a tyrosine kinase oncogene responsible for the pathogenesis of the majority of human ALK-positive lymphomas. We recently reported that it activated the Rac1 GTPase in anaplastic large-cell lymphoma (ALCL), leading to Rac-dependent formation of active invadopodia required for invasiveness. Herein, we went further into the study of this pathway and used the inhibitor of Rac, NSC23766, to validate its potential as a molecular target in ALCL in vitro and in vivo in a xenograft model and in a conditional model of NPM–ALK transgenic mice. Our data demonstrate that Rac regulates important effectors of NPM–ALK-induced transformation such as Erk1/2, p38 and Akt. Moreover, inhibition of Rac signaling abrogates NPM–ALK-elicited disease progression and metastasis in mice, highlighting the potential of small GTPases and their regulators as additional therapic targets in lymphomas

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat
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