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| 3. |
- Perrone, Alessio, et al.
(författare)
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Non-conventional Cu thin films deposited on Y substrate by sputtering
- 2014
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 752, s. 27-32
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Tidskriftsartikel (refereegranskat)abstract
- Copper (Cu) thin films were deposited on yttrium (Y) substrate by sputtering. During the deposition, a small central area of the Y substrate was shielded to avoid the film deposition and was successively used to study its photoemissive properties. This configuration has two advantages: the cathode presents (i) the quantum efficiency and the work function of Y and (ii) high electrical compatibility when inserted into the conventional radio-frequency gun built with Cu bulk. The photocathode was investigated by scanning electron microscopy to determine surface morphology. X-ray diffraction and atomic force microscopy studies were performed to compare the structure and surface properties of the deposited film. The measured electrical resistivity value of the Cu film was similar to that of high purity Cu bulk. Film to substrate adhesion was also evaluated using the Daimler–Benz Rockwell-C adhesion test method. Finally, the photoelectron performance in terms of quantum efficiency was obtained in a high vacuum photodiode cell before and after laser cleaning procedures. A comparison with the results obtained with a twin sample prepared by pulsed laser deposition is presented and discussed.
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| 4. |
- Steffen, Annika, et al.
(författare)
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Meat and Heme Iron Intake and Risk of Squamous Cell Carcinoma of the Upper Aero-Digestive Tract in the European Prospective Investigation into Cancer and Nutrition (EPIC)
- 2012
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Ingår i: Cancer Epidemiology Biomarkers & Prevention. - 1538-7755 .- 1055-9965. ; 21:12, s. 2138-2148
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Tidskriftsartikel (refereegranskat)abstract
- Background: Evidence from prospective studies on intake of meat and fish and risk of squamous cell carcinoma (SCC) of the upper aero-digestive tract (UADT) is scarce. We prospectively investigated the association of meat and fish intake with risk of SCC of the UADT and the possible mechanism via heme iron in the large multicenter European Prospective Investigation into Cancer and Nutrition (EPIC) study. Methods: Multivariable proportional hazards models were used to estimate relative risks (RR) of SCC of the UADT in relation to intake of total meat, as well as subtypes of meat, fish, and heme iron among 348,738 individuals from 7 European countries. Results: During an average follow-up of 11.8 years, a total of 682 incident cases of UADT SCC were accrued. Intake of processed meat was positively associated with risk of SCC of the UADT in the total cohort (highest vs. lowest quintile: RR = 1.41; 95% confidence interval (CI) = 1.03-1.941, however, in stratified analyses, this association was confined to the group of current smokers (highest vs. lowest quintile: RR = 1.89; 95% CI = 1.22-2.93). Red meat, poultry, fish, and heme iron were not consistently related to UADT SCC. Conclusion: Higher intake of processed meat was positively associated with KC of the UADT among smokers. Although this finding was stable in various sensitivity analyses, we cannot rule out residual confounding by smoking. Confirmation in future studies and identification of biologic mechanisms is warranted. Impact: Smokers may further increase their risk for SCC of the UADT if they additionally consume large amounts of processed meat. Cancer Epidemiol Biomarkers Prev; 21(12); 2738-48. (C)2012 AACR.
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| 6. |
- von der Lieth, Claus-Wilhelm, et al.
(författare)
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EUROCarbDB : an open-access platform for glycoinformatics
- 2011
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 21:4, s. 493-502
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Tidskriftsartikel (refereegranskat)abstract
- The EUROCarbDB project is a design study for a technical framework, which provides sophisticated, freely accessible, open-source informatics tools and databases to support glycobiology and glycomic research. EUROCarbDB is a relational database containing glycan structures, their biological context and, when available, primary and interpreted analytical data from high-performance liquid chromatography, mass spectrometry and nuclear magnetic resonance experiments. Database content can be accessed via a web-based user interface. The database is complemented by a suite of glycoinformatics tools, specifically designed to assist the elucidation and submission of glycan structure and experimental data when used in conjunction with contemporary carbohydrate research workflows. All software tools and source code are licensed under the terms of the Lesser General Public License, and publicly contributed structures and data are freely accessible. The public test version of the web interface to the EUROCarbDB can be found at http://www.ebi.ac.uk/eurocarb.
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| 7. |
- Alexiadis, Alessio, et al.
(författare)
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Comparison between CFD calculations of the flow in a rotating disk cell and the Cochran/Levich equations
- 2012
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Ingår i: Journal of Electroanalytical Chemistry. - : Elsevier BV. - 1572-6657. ; 669, s. 55-66
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Tidskriftsartikel (refereegranskat)abstract
- Three CFD (Computational Fluid Dynamics) models (single-phase. VOF and Euler-Euler) are employed to simulate the flow in a finite, rotating electrode cell under different operative conditions. The main dimensionless groups are derived and their effect on the flow is investigated. Except very close to the rotating electrode (i.e. in the hydrodynamic layer), the results show a flow pattern considerably different from Cochran's approximate analytical solution often used in electrochemistry. Historically, the Cochran equation was used to derive the Levich equation, which permits the calculation of the limiting current density on a rotating electrode. Despite the general inadequacy of Cochran's analytical solution, however, we show that the Levich equation often retains its validity because, in many practical situations, the concentration boundary layer is considerably smaller than the hydrodynamic boundary layer. When bubbles are generated on the electrode and a certain critical void fraction is exceeded, however, the Levich equation also becomes inaccurate. We propose, therefore, an amended version of this equation, which provides results closer to the CFD calculations.
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| 8. |
- Alexiadis, Alessio, et al.
(författare)
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Liquid-gas flow patterns in a narrow electrochemical channel
- 2011
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 66:10, s. 2252-2260
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Tidskriftsartikel (refereegranskat)abstract
- The flow in a narrow (3 mm wide) vertical gap of an electrochemical cell with gas evolution at one electrode is modeled by means of the two-phase Euler-Euler model. The results indicate that at certain conditions an unsteady type of flow with vortices and recirculation regions can occur. Such flow pattern has been observed experimentally, but not reported in previous modeling studies. Further analysis establishes that the presence of a sufficient amount of small (similar to 10 mu m) bubbles is the main factor causing this type of flow at high current densities.
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| 10. |
- Alexiadis, Alessio, et al.
(författare)
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On the stability of the flow in multi-channel electrochemical systems
- 2012
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Ingår i: Journal of Applied Electrochemistry. - : Springer Science and Business Media LLC. - 0021-891X .- 1572-8838. ; 42:9, s. 679-687
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Tidskriftsartikel (refereegranskat)abstract
- The importance of the fluid dynamics in the modelling of electrochemical systems is often underestimated. The knowledge of the flow velocity pattern in an electrochemical cell, in fact, can allow us to associate certain electrochemical reactions with specific fluid patterns to maximize the yield of some reaction and, conversely, to minimize unwanted or side reactions. The correct evaluation of the convective term in the Nernst-Planck equation, however, requires the solution of the so-called Navier-Stokes equations, and computational fluid dynamics (CFD) is today the established method to numerically solve these equations. In this work, a CFD model is employed to show that the gas-liquid flow pattern can be remarkably different in a single channel or in a multi-channel gas-evolving electrochemical system. In the single channel, in fact, under certain conditions, vortices and recirculation regions can appear in the flow, which does not appear in the multi-channel case. The reason of this difference is found in the uneven distribution of the small bubbles in the two cases. Additionally, a second, simplified, model of the flow is discussed to show how a higher concentration of small bubbles in the single channel system can destabilize the flow.
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