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Records |
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Author |
Sree, S.P.; Dendooven, J.; Masschaele, K.; Hamed, H.M.; Deng, S.; Bals, S.; Detavernier, C.; Martens, J.A. |
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Title |
Synthesis of uniformly dispersed anatase nanoparticles inside mesoporous silica thin films via controlled breakup and crystallization of amorphous TiO2 deposited using atomic layer deposition |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Nanoscale |
Abbreviated Journal |
Nanoscale |
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| |
Volume |
5 |
Issue |
11 |
Pages |
5001-5008 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Amorphous titanium dioxide was introduced into the pores of mesoporous silica thin films with 75% porosity and 12 nm average pore diameter via Atomic Layer Deposition (ALD) using alternating pulses of tetrakis(dimethylamino)titanium and water. Calcination provoked fragmentation of the deposited amorphous TiO2 phase and its crystallization into anatase nanoparticles inside the nanoporous film. The narrow particle size distribution of 4 ± 2 nm and the uniform dispersion of the particles over the mesoporous silica support were uniquely revealed using electron tomography. These anatase nanoparticle bearing films showed photocatalytic activity in methylene blue degradation. This new synthesis procedure of the anatase nanophase in mesoporous silica films using ALD is a convenient fabrication method of photocatalytic coatings amenable to application on very small as well as very large surfaces |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Cambridge |
Editor |
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Language |
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Wos  |
000319008700056 |
Publication Date |
2013-04-09 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2040-3364;2040-3372; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
7.367 |
Times cited |
22 |
Open Access |
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| |
Notes |
Fwo; Iap-Pai; Erc |
Approved |
Most recent IF: 7.367; 2013 IF: 6.739 |
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Call Number |
UA @ lucian @ c:irua:108774 |
Serial |
3460 |
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| Permanent link to this record |
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Author |
Mourdikoudis, S.; Chirea, M.; Altantzis, T.; Pastoriza-Santos, I.; Perez-Juste, J.; Silva, F.; Bals, S.; Liz-Marzan, L.M. |
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Title |
Dimethylformamide-mediated synthesis of water-soluble platinum nanodendrites for ethanol oxidation electrocatalysis |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Nanoscale |
Abbreviated Journal |
Nanoscale |
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| |
Volume |
5 |
Issue |
11 |
Pages |
4776-4784 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Herein we describe the synthesis of water-soluble platinum nanodendrites in dimethylformamide (DMF), in the presence of polyethyleneimine (PEI) as a stabilizing agent. The average size of the dendrites is in the range of 20-25 nm while their porosity can be tuned by modifying the concentration of the metal precursor. Electron tomography revealed different crystalline orientations of nanocrystallites in the nanodendrites and allowed a better understanding of their peculiar branching and porosity. The high surface area of the dendrites (up to 22 m(2) g(-1)) was confirmed by BET measurements, while X-ray diffraction confirmed the abundance of high-index facets in the face-centered-cubic crystal structure of Pt. The prepared nanodendrites exhibit excellent performance in the electrocatalytic oxidation of ethanol in alkaline solution. Sensing, selectivity, cycleability and great tolerance toward poisoning were demonstrated by cyclic voltammetry measurements. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Cambridge |
Editor |
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Language |
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Wos |
000319008700028 |
Publication Date |
2013-04-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2040-3364;2040-3372; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
7.367 |
Times cited |
50 |
Open Access |
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Notes |
Esf; 262348 Esmi |
Approved |
Most recent IF: 7.367; 2013 IF: 6.739 |
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Call Number |
UA @ lucian @ c:irua:109060 |
Serial |
705 |
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| Permanent link to this record |
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Author |
Stefaniak, E.A.; Darchuk, L.; Sapundjiev, D.; Kips, R.; Aregbe, Y.; Van Grieken, R. |
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Title |
New insight into UO2F2 particulate structure by micro-Raman spectroscopy |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Journal of molecular structure |
Abbreviated Journal |
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Volume |
1040 |
Issue |
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Pages |
206-212 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Uranyl fluoride particles produced via hydrolysis of uranium hexafluoride have been deposited on different substrates: polished graphite disks, silver foil, stainless steel and gold-coated silicon wafer, and measured with micro-Raman spectroscopy (MRS). All three metallic substrates enhanced the Raman signal delivered by UO2F2 in comparison to graphite. The fundamental stretching of the UO band appeared at 867 cm−1 in case of the graphite substrate, while in case of the others it was shifted to lower frequencies (down to 839 cm−1). All applied metallic substrates showed the expected effect of Raman signal enhancement; however the gold layer appeared to be most effective. Application of new substrates provides more information on the molecular structure of uranyl fluoride precipitation, which is interesting for nuclear safeguards and nuclear environmental analysis. |
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Corporate Author |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000318961000027 |
Publication Date |
2013-02-19 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-2860 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:107123 |
Serial |
8299 |
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| Permanent link to this record |
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Author |
Singh, S.K.; Neek-Amal, M.; Costamagna, S.; Peeters, F.M. |
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Title |
Thermomechanical properties of a single hexagonal boron nitride sheet |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
87 |
Issue |
18 |
Pages |
184106-184107 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Using atomistic simulations we investigate the thermodynamical properties of a single atomic layer of hexagonal boron nitride (h-BN). The thermal induced ripples, heat capacity, and thermal lattice expansion of large scale h-BN sheets are determined and compared to those found for graphene (GE) for temperatures up to 1000 K. By analyzing the mean-square height fluctuations < h(2)> and the height-height correlation function H(q) we found that the h-BN sheet is a less stiff material as compared to graphene. The bending rigidity of h-BN (i) is about 16% smaller than the one of GE at room temperature (300 K), and (ii) increases with temperature as in GE. The difference in stiffness between h-BN and GE results in unequal responses to external uniaxial and shear stress and different buckling transitions. In contrast to a GE sheet, the buckling transition of a h-BN sheet depends strongly on the direction of the applied compression. The molar heat capacity, thermal-expansion coefficient, and Gruneisen parameter are estimated to be 25.2 J mol(-1) K-1, 7.2 x 10(-6) K-1, and 0.89, respectively. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000318653800001 |
Publication Date |
2013-05-08 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
80 |
Open Access |
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Notes |
; We thank K. H. Michel and D. A. Kirilenko for their useful comments on the manuscript. M. N.-A. was supported by EU-Marie Curie IIF Postdoctorate Fellowship No. 299855. S. Costamagna was supported by the Belgian Science Foundation (BELSPO). This work was supported by the ESF-EuroGRAPHENE project CONGRAN, the Flemish Science Foundation (FWO-Vl), and the Methusalem program of the Flemish Government. ; |
Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
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Call Number |
UA @ lucian @ c:irua:109010 |
Serial |
3638 |
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| Permanent link to this record |
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Author |
Dixit, H.; Tandon, N.; Cottenier, S.; Saniz, R.; Lamoen, D.; Partoens, B. |
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Title |
First-principles study of possible shallow donors in ZnAl2O4 spinel |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
87 |
Issue |
17 |
Pages |
174101-174107 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
ZnAl2O4 (gahnite) is a ceramic which is considered a possible transparent conducting oxide (TCO) due to its wide band gap and transparency for UV. Defects play an important role in controlling the conductivity of a TCO material along with the dopant, which is the main source of conductivity in an otherwise insulating oxide. A comprehensive first-principles density functional theory study for point defects in ZnAl2O4 spinel is presented using the Heyd, Scuseria, and Ernzerhof hybrid functional (HSE06) to overcome the band gap problem. We have investigated the formation energies of intrinsic defects which include the Zn, Al, and O vacancy and the antisite defects: Zn at the Al site (ZnAl) and Al at the Zn site (AlZn). The antisite defect AlZn has the lowest formation energy and acts as a shallow donor, indicating possible n-type conductivity in ZnAl2O4 spinel by Al doping. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000318653300001 |
Publication Date |
2013-05-08 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
3.836 |
Times cited |
50 |
Open Access |
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Notes |
Iwt; Fwo |
Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
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Call Number |
UA @ lucian @ c:irua:108769 |
Serial |
1219 |
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| Permanent link to this record |
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Author |
Van Holsbeke, C.; Vos, W.; van Hoorenbeeck, K.; Boudewyns, A.; Salgado, R.; Verdonck, P.R.; Ramet, J.; de Backer, J.; De Backer, W.; Verhulst, S.L. |
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Title |
Functional respiratory imaging as a tool to assess upper airway patency in children with obstructive sleep apnea |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Sleep Medicine |
Abbreviated Journal |
Sleep Med |
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Volume |
14 |
Issue |
5 |
Pages |
433-439 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT); Laboratory Experimental Medicine and Pediatrics (LEMP) |
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Abstract |
Objective: We aim to investigate if anatomical and functional properties of the upper airway using computerized 3D models derived from computed tomography (CT) scans better predict obstructive sleep apnea (OSA) severity than standard clinical markers. Methods: Consecutive children with suspected OSA underwent polysomnography, clinical assessment of upper airway patency, and a CT scan while awake. A three-dimensional (3D) reconstruction of the pharyngeal airway was built from these images, and computational fluid dynamics modeling of low inspiratory flow was performed using open-source software. Results: Thirty-three children were included (23 boys; mean age, was 6.0 +/- 3.2 y). OSA was diagnosed in 23 patients. Children with OSA had a significantly lower volume of the overlap region between tonsils and the adenoids (median volume, 1408 mm compared to 2173 mm; p = 0.04), a lower mean cross-sectional area at this location (median volume, 69.3 mm(2) compared to 114.3 mm(2); p = 0.04), and a lower minimal cross-sectional area (median volume, 17.9 mm(2) compared to 25.9 mm(2); p = 0.05). Various significant correlations were found between several imaging parameters and the severity of OSA, most pronounced for upper airway conductance (r = -0.46) (p < 0.01) for correlation between upper airway conductance and the apnea-hypopnea index. No differences or significant correlations were observed with clinical parameters of upper airway patency. Preliminary data after treatment showed that none of the patients with residual OSA had their smallest cross-sectional area located in segment 3, and this frequency was significantly lower than in their peers whose sleep study normalized (64%; p = 0.05). Conclusion: Functional imaging parameters are highly correlated with OSA severity and are a more powerful correlate than clinical scores of upper airway patency. Preliminary data also showed that we could identify differences in the upper airway of those subjects who did not benefit from a local upper airway treatment. (c) 2013 Elsevier B.V. All rights reserved. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000318612100009 |
Publication Date |
2013-03-07 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1389-9457; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.391 |
Times cited |
18 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 3.391; 2013 IF: 3.100 |
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Call Number |
UA @ lucian @ c:irua:109015 |
Serial |
1302 |
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Author |
Zhang, S.; Van Gaens, W.; van Gessel, B.; Hofmann, S.; van Veldhuizen, E.; Bogaerts, A.; Bruggeman, P. |
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Title |
Spatially resolved ozone densities and gas temperatures in a time modulated RF driven atmospheric pressure plasma jet : an analysis of the production and destruction mechanisms |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Journal of physics: D: applied physics |
Abbreviated Journal |
J Phys D Appl Phys |
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Volume |
46 |
Issue |
20 |
Pages |
205202-205212 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
In this work, a time modulated RF driven DBD-like atmospheric pressure plasma jet in Ar + 2%O2, operating at a time averaged power of 6.5 W is investigated. Spatially resolved ozone densities and gas temperatures are obtained by UV absorption and Rayleigh scattering, respectively. Significant gas heating in the core of the plasma up to 700 K is found and at the position of this increased gas temperature a depletion of the ozone density is found. The production and destruction reactions of O3 in the jet effluent as a function of the distance from the nozzle are obtained from a zero-dimensional chemical kinetics model in plug flow mode which considers relevant air chemistry due to air entrainment in the jet fluent. A comparison of the measurements and the models show that the depletion of O3 in the core of the plasma is mainly caused by an enhanced destruction of O3 due to a large atomic oxygen density. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
London |
Editor |
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Language |
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Wos |
000318546100008 |
Publication Date |
2013-05-02 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-3727;1361-6463; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.588 |
Times cited |
74 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.588; 2013 IF: 2.521 |
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Call Number |
UA @ lucian @ c:irua:107840 |
Serial |
3067 |
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Author |
Godoi, R.H.M.; Carneiro, B.H.B.; Paralovo, S.L.; Campos, V.P.; Tavares, T.M.; Evangelista, H.; Van Grieken, R.; Godoi, A.F.L. |
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Title |
Indoor air quality of a museum in a subtropical climate : the Oscar Niemeyer museum in Curitiba, Brazil |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
The science of the total environment |
Abbreviated Journal |
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Volume |
452 |
Issue |
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Pages |
314-320 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
The assessment of damage to indoor cultural heritage, in particular by pollutants, is nowadays a major and growing concern for curators and conservators. Nevertheless, although many museums have been widely investigated in Europe, the effects of particulate matter and gaseous pollutants in museums under tropical and subtropical climates and with different economic realities are still unclear. An important portion of the world's cultural heritage is currently in tropical countries where both human and financial resources for preserving museum collections are limited. Hence, our aim is to assess the damage that can be caused to the artwork by pollution in hot and humid environments, where air quality and microclimatic condition differences can cause deterioration. As a case study, particulate matter as well as gases were collected at the Oscar Niemeyer Museum (MON) in Curitiba, Brazil, where large modern and contemporary works of art are displayed. NO2, SO2, O3, Acetic Acid, Formic Acids and BTEX, in the ambient air, were sampled by means of passive diffusive sampling and their concentrations were determined by IC or GCMS. The particulate matter was collected in bulk form and analyzed with the use of energy dispersive X-ray fluorescence and aethalometer. The chemical compositions of individual particles were quantitatively elucidated, including low-Z components like C, N and O, as well as higher-Z elements, using automated electron probe microanalysis. The gaseous and particulate matter levels were then compared with the concentrations obtained for the same pollutants in other museums, located in places with different climates, and with some reference values provided by international cultural heritage conservation centers. Results are interpreted separately and as a whole with the specific aim of identifying compounds that could contribute to the chemical reactions taking place on the surfaces of artifacts and which could potentially cause irreversible damage to the artworks. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Language |
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Wos |
000318530600034 |
Publication Date |
2013-03-23 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0048-9697; 1879-1026 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:106766 |
Serial |
8083 |
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Author |
Goux, L.; Fantini, A.; Govoreanu, B.; Kar, G.; Clima, S.; Chen, Y.-Y.; Degraeve, R.; Wouters, D.J.; Pourtois, G.; Jurczak, M. |
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Title |
Asymmetry and switching phenomenology in TiN\ (Al2O3) \ HfO2 \ Hf systems |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
ECS solid state letters |
Abbreviated Journal |
Ecs Solid State Lett |
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Volume |
1 |
Issue |
4 |
Pages |
63-65 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
In this letter, we address the bipolar resistive switching phenomenology in scaled TiN\HfO2\Hf cells. By means of stack engineering using a thin Al2O3 layer inserted either at the TiN\HfO2 or at the Hf\HfO2 interface, we demonstrate that the reset operation takes place close to the TiNanode. Due to the increase of the oxygen-vacancy profile from the TiN to the Hf interface, the filament-confining and wide band-gap Al2O3 layer should indeed be engineered at the interface with the TiN electrode in order to further improve the switching control and to allow reaching larger state resistances. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.003204ssl] All rights reserved. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
Electrochemical society |
Place of Publication |
Pennington (N.J.) |
Editor |
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Language |
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Wos |
000318340300005 |
Publication Date |
2012-08-23 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2162-8742;2162-8750; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.184 |
Times cited |
11 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.184; 2012 IF: NA |
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Call Number |
UA @ lucian @ c:irua:108530 |
Serial |
160 |
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| Permanent link to this record |
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Author |
Shuhui Sun, Gaixia Zhang, Nicolas Gauquelin, Ning Chen, Jigang Zhou, Songlan Yang, Weifeng Chen, Xiangbo Meng, Dongsheng Geng, Mohammad N. Banis, Ruying Li, Siyu Ye, Shanna Knights, Gianluigi A. Botton, Tsun-Kong Sham & Xueliang Sun |
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Title |
Single-atom Catalysis Using Pt/Graphene Achieved through Atomic Layer Deposition |
Type |
A1 Journal Article |
| |
Year |
2013 |
Publication |
Scientific Reports |
Abbreviated Journal |
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Volume |
3 |
Issue |
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Pages |
1775 |
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Keywords |
A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; |
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Abstract |
Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and
automobile industries. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize
their use efficiency, however, very challenging. Here we report a practical synthesis for isolated single Pt
atoms anchored to graphene nanosheet using the atomic layer deposition (ALD) technique. ALD offers the
capability of precise control of catalyst size span from single atom, subnanometer cluster to nanoparticle.
The single-atom catalysts exhibit significantly improved catalytic activity (up to 10 times) over that of the
state-of-the-art commercial Pt/C catalyst. X-ray absorption fine structure (XAFS) analyses reveal that the
low-coordination and partially unoccupied densities of states of 5d orbital of Pt atoms are responsible for the
excellent performance. This work is anticipated to form the basis for the exploration of a next generation of
highly efficient single-atom catalysts for various applications. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000318334300004 |
Publication Date |
2013-05-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
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Series Issue |
|
Edition |
|
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| |
ISSN |
|
ISBN |
|
Additional Links |
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| |
Impact Factor |
|
Times cited |
345 |
Open Access |
|
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| |
Notes |
|
Approved |
Most recent IF: NA |
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| |
Call Number |
EMAT @ emat @ |
Serial |
4543 |
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| Permanent link to this record |
| |
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| |
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Author |
Neyts, E.C.; Bogaerts, A. |
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| |
Title |
Combining molecular dynamics with Monte Carlo simulations : implementations and applications |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Theoretical chemistry accounts : theory, computation, and modeling |
Abbreviated Journal |
Theor Chem Acc |
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| |
Volume |
132 |
Issue |
2 |
Pages |
1320-12 |
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| |
Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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| |
Abstract |
In this contribution, we present an overview of the various techniques for combining atomistic molecular dynamics with Monte Carlo simulations, mainly in the context of condensed matter systems, as well as a brief summary of the main accelerated dynamics techniques. Special attention is given to the force bias Monte Carlo technique and its combination with molecular dynamics, in view of promising recent developments, including a definable timescale. Various examples of the application of combined molecular dynamics / Monte Carlo simulations are given, in order to demonstrate the enhanced simulation efficiency with respect to either pure molecular dynamics or Monte Carlo. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
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Wos |
000318294700010 |
Publication Date |
2012-12-19 |
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
1432-881X;1432-2234; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
1.89 |
Times cited |
27 |
Open Access |
|
|
| |
Notes |
|
Approved |
Most recent IF: 1.89; 2013 IF: 2.143 |
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| |
Call Number |
UA @ lucian @ c:irua:104725 |
Serial |
404 |
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| Permanent link to this record |
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| |
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Author |
Rossell, M.D.; Abakumov, A.M.; Ramasse, Q.M.; Erni, R. |
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| |
Title |
Direct evidence of stacking disorder in the mixed ionic-electronic conductor Sr4Fe6O12+\delta |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
ACS nano |
Abbreviated Journal |
Acs Nano |
|
| |
Volume |
7 |
Issue |
4 |
Pages |
3078-3085 |
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| |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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| |
Abstract |
Determining the structure-to-property relationship of materials becomes particularly challenging when the material under investigation is dominated by defects and structural disorder. Knowledge on the exact atomic arrangement at the defective structure is required to understand its influence on the functional properties. However, standard diffraction techniques deliver structural information that is averaged over many unit cells. In particular, information about defects and order-disorder phenomena is contained in the coherent diffuse scattering intensity which often is difficult to uniquely interpret. Thus, the examination of the local disorder in materials requires a direct method to study their structure on the atomic level with chemical sensitivity. Using aberration-corrected scanning transmission electron microscopy in combination with atomic-resolution electron energy-loss spectroscopy, we show that the controversial structural arrangement of the Fe2O2+delta layers in the mixed ionic-electronic conducting Sr4Fe6O12+delta perovskite can be unambiguously resolved. Our results provide direct experimental evidence for the presence of a nanomixture of “ordered” and “disordered” domains in an epitaxial Sr4Fe6O12+delta thin film. The most favorable arrangement is the disordered structure and is interpreted as a randomly occurring but well-defined local shift of the Fe-O chains in the Fe2O2+delta layers. By analyzing the electron energy-loss near-edge structure of the different building blocks in the Sr4Fe6O12+delta unit cell we find that the mobile holes in this mixed ionic-electronic conducting oxide are highly localized in the Fe2O2+delta layers, which are responsible for the oxide-ion conductivity. A possible link between disorder and oxygen-ion transport along the Fe2O2+delta layers is proposed by arguing that the disorder can effectively break the oxygen diffusion pathways. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
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Wos |
000318143300021 |
Publication Date |
2013-03-04 |
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
1936-0851;1936-086X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
13.942 |
Times cited |
4 |
Open Access |
|
|
| |
Notes |
|
Approved |
Most recent IF: 13.942; 2013 IF: 12.033 |
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| |
Call Number |
UA @ lucian @ c:irua:108476 |
Serial |
713 |
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| Permanent link to this record |
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| |
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Author |
Buysse, C.; Michielsen, B.; Middelkoop, V.; Snijkers, F.; Buekenhondt, A.; Kretzschmar, J.; Lenaerts, S. |
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| |
Title |
Modeling of the performance of BSCF capillary membranes in four-end and three-end integration mode |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Ceramics international |
Abbreviated Journal |
Ceram Int |
|
| |
Volume |
39 |
Issue |
4 |
Pages |
4113-4123 |
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| |
Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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| |
Abstract |
Owing to their high surface-to-volume ratio, there has been an increasing research interest in mixed ionic electronic conducting (MIEC) capillary membranes for large-scale high temperature oxygen separation applications. They offer an energy-efficient solution for high temperature combustion processes in oxy-fuel and pre-combustion CO2 capture technologies used in fossil fuel power plants. In order to assess the effectiveness of these membranes in power plant applications, the impact of the geometry of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) capillaries on their performance in the three-end and four-end integration modes has been investigated and thoroughly discussed. The model's parameters were derived from four-end mode lab-scale experiments using gas-tight, macrovoid free and sulfur-free BSCF capillary membranes that were prepared by a phase-inversion spinning technique. The results of this modeling study revealed that in the four-end mode higher average oxygen fluxes and smaller total membrane areas can be obtained than in the three-end mode. This is due to the higher pO(2) gradient across the membrane wall. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000318129100084 |
Publication Date |
2012-11-09 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
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Edition |
|
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| |
ISSN |
0272-8842 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
2.986 |
Times cited |
4 |
Open Access |
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| |
Notes |
; The authors wish to thank all the VITO staff involved in the project for their continued support, and in particular B. Molenberghs, W. Doyen, H. Beckers and S. Mullens. C. Buysse would like to acknowledge funding from VITO and the University of Antwerp for a Ph.D. studentship. This work has been performed in the framework of the German Helmholtz Alliance Project “MEM-BRAIN”, aiming at the development of gas separation membranes for zero-emission fossil fuel power plants. ; |
Approved |
Most recent IF: 2.986; 2013 IF: 2.086 |
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| |
Call Number |
UA @ admin @ c:irua:109020 |
Serial |
5971 |
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| Permanent link to this record |
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Author |
Fougerolle, Y.D.; Truchetet, F.; Demonceaux, C.; Gielis, J. |
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Title |
A robust evolutionary algorithm for the recovery of rational Gielis curves |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Pattern recognition |
Abbreviated Journal |
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| |
Volume |
46 |
Issue |
8 |
Pages |
2078-2091 |
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| |
Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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| |
Abstract |
Gielis curves (GC) can represent a wide range of shapes and patterns ranging from star shapes to symmetric and asymmetric polygons, and even self intersecting curves. Such patterns appear in natural objects or phenomena, such as flowers, crystals, pollen structures, animals, or even wave propagation. Gielis curves and surfaces are an extension of Lamé curves and surfaces (superquadrics) which have benefited in the last two decades of extensive researches to retrieve their parameters from various data types, such as range images, 2D and 3D point clouds, etc. Unfortunately, the most efficient techniques for superquadrics recovery, based on deterministic methods, cannot directly be adapted to Gielis curves. Indeed, the different nature of their parameters forbids the use of a unified gradient descent approach, which requires initial pre-processings, such as the symmetry detection, and a reliable pose and scale estimation. Furthermore, even the most recent algorithms in the literature remain extremely sensitive to initialization and often fall into local minima in the presence of large missing data. We present a simple evolutionary algorithm which overcomes most of these issues and unifies all of the required operations into a single though efficient approach. The key ideas in this paper are the replacement of the potential fields used for the cost function (closed form) by the shortest Euclidean distance (SED, iterative approach), the construction of cost functions which minimize the shortest distance as well as the curve length using R-functions, and slight modifications of the evolutionary operators. We show that the proposed cost function based on SED and R-function offers the best compromise in terms of accuracy, robustness to noise, and missing data. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000317944800002 |
Publication Date |
2013-01-29 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
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| |
ISSN |
0031-3203 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
|
Times cited |
|
Open Access |
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Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:107181 |
Serial |
8485 |
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| Permanent link to this record |
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Author |
Borgatti, F.; Park, C.; Herpers, A.; Offi, F.; Egoavil, R.; Yamashita, Y.; Yang, A.; Kobata, M.; Kobayashi, K.; Verbeeck, J.; Panaccione, G.; Dittmann, R.; |
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Title |
Chemical insight into electroforming of resistive switching manganite heterostructures |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Nanoscale |
Abbreviated Journal |
Nanoscale |
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| |
Volume |
5 |
Issue |
9 |
Pages |
3954-3960 |
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| |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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| |
Abstract |
We have investigated the role of the electroforming process in the establishment of resistive switching behaviour for Pt/Ti/Pr0.5Ca0.5MnO3/SrRuO3 layered heterostructures (Pt/Ti/PCMO/SRO) acting as non-volatile Resistance Random Access Memories (RRAMs). Electron spectroscopy measurements demonstrate that the higher resistance state resulting from electroforming of as-prepared devices is strictly correlated with the oxidation of the top electrode Ti layer through field-induced electromigration of oxygen ions. Conversely, PCMO exhibits oxygen depletion and downward change of the chemical potential for both resistive states. Impedance spectroscopy analysis, supported by the detailed knowledge of these effects, provides an accurate model description of the device resistive behaviour. The main contributions to the change of resistance from the as-prepared (low resistance) to the electroformed (high resistance) states are respectively due to reduced PCMO at the boundary with the Ti electrode and to the formation of an anisotropic np junction between the Ti and the PCMO layers. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Cambridge |
Editor |
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| |
Language |
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Wos |
000317859400051 |
Publication Date |
2013-03-05 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
2040-3364;2040-3372; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
7.367 |
Times cited |
40 |
Open Access |
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| |
Notes |
Vortex; Countatoms ECASJO_; |
Approved |
Most recent IF: 7.367; 2013 IF: 6.739 |
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| |
Call Number |
UA @ lucian @ c:irua:108710UA @ admin @ c:irua:108710 |
Serial |
348 |
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| Permanent link to this record |
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Author |
Schouteden, K.; Zeng, Y.-J.; Lauwaet, K.; Romero, C.P.; Goris, B.; Bals, S.; Van Tendeloo, G.; Lievens, P.; Van Haesendonck, C. |
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| |
Title |
Band structure quantization in nanometer sized ZnO clusters |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Nanoscale |
Abbreviated Journal |
Nanoscale |
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| |
Volume |
5 |
Issue |
9 |
Pages |
3757-3763 |
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| |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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| |
Abstract |
Nanometer sized ZnO clusters are produced in the gas phase and subsequently deposited on clean Au(111) surfaces under ultra-high vacuum conditions. The zinc blende atomic structure of the approximately spherical ZnO clusters is resolved by high resolution scanning transmission electron microscopy. The large band gap and weak n-type conductivity of individual clusters are determined by scanning tunnelling microscopy and spectroscopy at cryogenic temperatures. The conduction band is found to exhibit clear quantization into discrete energy levels, which can be related to finite-size effects reflecting the zero-dimensional confinement. Our findings illustrate that gas phase cluster production may provide unique possibilities for the controlled fabrication of high purity quantum dots and heterostructures that can be size selected prior to deposition on the desired substrate under controlled ultra-high vacuum conditions. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Cambridge |
Editor |
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Language |
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Wos |
000317859400026 |
Publication Date |
2013-03-05 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
2040-3364;2040-3372; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
7.367 |
Times cited |
13 |
Open Access |
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| |
Notes |
FWO; Hercules; COUNTATOMS |
Approved |
Most recent IF: 7.367; 2013 IF: 6.739 |
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| |
Call Number |
UA @ lucian @ c:irua:108518 |
Serial |
219 |
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| Permanent link to this record |
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Author |
Zhukova, A.A.; Rumyantseva, M.N.; Zaytsev, V.B.; Zaytseva, A.V.; Abakumov, A.M.; Gaskov, A.M. |
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Title |
Pd nanoparticles on SnO2(Sb) whiskers : aggregation and reactivity in CO detection |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Journal of alloys and compounds |
Abbreviated Journal |
J Alloy Compd |
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| |
Volume |
565 |
Issue |
|
Pages |
6-10 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Single crystal antimony-doped SnO2 whiskers have been synthesized by in situ doping process in horizontal flow reactor. The produced whiskers were modified with 0.1, 0.2, 0.5, 1 or 2 wt.% Pd. The processes of Pd particles growth and aggregation are described on the base of AFM and STEM data. Depending on the content of introduced Pd precursor, the various mechanisms (Volmer-Weber or Stranski-Krastanov) of Pd nanoparticles growth realize. The dependence of sensor signal to CO on Pd concentration has non-monotonous character determined by the size of Pd nanoparticles and their aggregation degree. The best sensor signal toward CO was observed for whiskers decorated with 0.1 wt.% Pd. This concentration corresponds to the presence of individual 3-5 nm Pd nanoparticles on the surface of the whiskers. (C) 2013 Elsevier B.V. All rights reserved. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
|
Place of Publication |
Amsterdam |
Editor |
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| |
Language |
|
Wos |
000317815300002 |
Publication Date |
2013-03-13 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
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| |
ISSN |
0925-8388; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
3.133 |
Times cited |
|
Open Access |
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Notes |
|
Approved |
Most recent IF: 3.133; 2013 IF: 2.726 |
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Call Number |
UA @ lucian @ c:irua:108424 |
Serial |
2566 |
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| Permanent link to this record |
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Author |
Barba-Ortega, J.; Sardella, E.; Aguiar, J.A.; Peeters, F.M. |
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Title |
Non-conventional vortex configurations in a mesoscopic flat disk |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Physica: C : superconductivity |
Abbreviated Journal |
Physica C |
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Volume |
487 |
Issue |
|
Pages |
47-55 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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| |
Abstract |
The influence of superficial defects on the vortex configurations of a thin superconducting disk is investigated within the time dependent Ginzburg-Landau formalism. The free energy, magnetization, vorticity, and the Cooper pair density are calculated for both metastable and stable vortex configurations and different number of defects on its surface in the presence of an external magnetic field applied perpendicular to the disk area. We show that the competition between the confinement geometry and the geometric position of the defects leads to non-conventional vortex configurations which are not compatible with the symmetry of the sample geometry. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000317743300009 |
Publication Date |
2013-02-27 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
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Edition |
|
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| |
ISSN |
0921-4534; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
1.404 |
Times cited |
17 |
Open Access |
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| |
Notes |
; This work was partially supported by the Brazilian agencies CNPq, CAPES, FACEPE (APQ 0589-105/08), FAPESP, CNPq-FWO bilateral project, and Colombian Agencies Colciencias and DIB. ; |
Approved |
Most recent IF: 1.404; 2013 IF: 1.110 |
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| |
Call Number |
UA @ lucian @ c:irua:108486 |
Serial |
2344 |
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| Permanent link to this record |
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Author |
Alfeld, M.; Pedroso, J.V.; van Hommes, M.E.; van der Snickt, G.; Tauber, G.; Blaas, J.; Haschke, M.; Erler, K.; Dik, J.; Janssens, K. |
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| |
Title |
A mobile instrument for in situ scanning macro-XRF investigation of historical paintings |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Journal of analytical atomic spectrometry |
Abbreviated Journal |
J Anal Atom Spectrom |
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| |
Volume |
28 |
Issue |
5 |
Pages |
760-767 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
Scanning macro-X-ray fluorescence analysis (MA-XRF) is rapidly being established as a technique for the investigation of historical paintings. The elemental distribution images acquired by this method allow for the visualization of hidden paint layers and thus provide insight into the artist's creative process and the painting's conservation history. Due to the lack of a dedicated, commercially available instrument the application of the technique was limited to a few groups that constructed their own instruments. We present the first commercially available XRF scanner for paintings, consisting of an X-ray tube mounted with a Silicon-Drift (SD) detector on a motorized stage to be moved in front of a painting. The scanner is capable of imaging the distribution of the main constituents of surface and sub-surface paint layers in an area of 80 by 60 square centimeters with dwell times below 10 ms and a lateral resolution below 100 mu m. The scanner features for a broad range of elements between Ti (Z = 22) and Mo (Z = 42) a count rate of more than 1000 counts per second (cps)?mass percent and detection limits of 100 ppm for measurements of 1 s duration. Next to a presentation of spectrometric figures of merit, the value of the technique is illustrated through a case study of a painting by Rembrandt's student Govert Flinck (1615-1660). |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000317674200019 |
Publication Date |
2013-03-22 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
0267-9477 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
3.379 |
Times cited |
106 |
Open Access |
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Notes |
; This research was supported by the Interuniversity Attraction Poles Programme – Belgian Science Policy (IUAP VI/16). The text also presents the results of GOA “XANES meets ELNES” (Research Fund University of Antwerp, Belgium) and from FWO (Brussels, Belgium) projects no. G.0704.08 and G.01769.09. M. Alfeld receives a Ph. D. fellowship of the Research Foundation-Flanders (FWO). We thank J. Langerock for allowing us to examine the portable altar triptych shown in Fig. 5. ; |
Approved |
Most recent IF: 3.379; 2013 IF: 3.396 |
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Call Number |
UA @ admin @ c:irua:108517 |
Serial |
5453 |
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| Permanent link to this record |
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Author |
Orlova, N.V.; Shanenko, A.A.; Milošević, M.V.; Peeters, F.M.; Vagov, A.V.; Axt, V.M. |
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Title |
Ginzburg-Landau theory for multiband superconductors : microscopic derivation |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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| |
Volume |
87 |
Issue |
13 |
Pages |
134510-134518 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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| |
Abstract |
A procedure to derive the Ginzburg-Landau (GL) theory from the multiband BCS Hamiltonian is developed in a general case with an arbitrary number of bands and arbitrary interaction matrix. It combines the standard Gor'kov truncation and a subsequent reconstruction in order to match accuracies of the obtained terms. This reconstruction recovers the phenomenological GL theory as obtained from the Landau model of phase transitions but offers explicit microscopic expressions for the relevant parameters. Detailed calculations are presented for a three-band system treated as a prototype multiband superconductor. It is demonstrated that the symmetry in the coupling matrix may lead to the chiral ground state with the phase frustration, typical for systems with broken time-reversal symmetry. DOI: 10.1103/PhysRevB.87.134510 |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000317586700002 |
Publication Date |
2013-04-16 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
3.836 |
Times cited |
57 |
Open Access |
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| |
Notes |
; This work was supported by the “Odysseus” Program of the Flemish Government and the Flemish Science Foundation (FWO-Vl). A.A.S. acknowledges useful discussions with D. Neilson. ; |
Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
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| |
Call Number |
UA @ lucian @ c:irua:108464 |
Serial |
1344 |
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| Permanent link to this record |
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Author |
Verheyen, E.; Jo, C.; Kurttepeli, M.; Vanbutsele, G.; Gobechiya, E.; Korányi, T.I.; Bals, S.; Van Tendeloo, G.; Ryoo, R.; Kirschhock, C.E.A.; Martens, J.A.; |
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Title |
Molecular shape-selectivity of MFI zeolite nanosheets in n-decane isomerization and hydrocracking |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Journal of catalysis |
Abbreviated Journal |
J Catal |
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| |
Volume |
300 |
Issue |
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Pages |
70-80 |
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| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
MFI zeolite nanosheets with thickness of 2 and 8 nm were synthesized, transformed into bifunctional catalysts by loading with platinum and tested in n-decane isomerization and hydrocracking. Detailed analysis of skeletal isomers and hydrocracked products revealed that the MFI nanosheets display transition-state shape-selectivity similar to bulk MFI zeolite crystals. The suppressed formation of bulky skeletal isomers and C5 cracking products are observed both in the nanosheets and the bulk crystals grown in three dimensions. This is typical for restricted transition-state shape-selectivity, characteristic for the MFI type pores. It is a first clear example of transition-state shape-selectivity inside a zeolitic nanosheet. Owing to the short diffusion path across the sheets, expression of diffusion-based discrimination of reaction products in the MFI nanosheets was limited. The 2-methylnonane formation among monobranched C10 isomers and 2,7-dimethyloctane among dibranched C10 isomers, which in MFI zeolite are favored by product diffusion, was much less favored on the nanosheets compared to the reference bulk ZSM-5 material. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
San Diego, Calif. |
Editor |
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Language |
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Wos |
000317558000009 |
Publication Date |
2013-02-07 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-9517; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.844 |
Times cited |
121 |
Open Access |
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Notes |
Methusalem; IAP; Countatoms |
Approved |
Most recent IF: 6.844; 2013 IF: 6.073 |
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| |
Call Number |
UA @ lucian @ c:irua:106186 |
Serial |
2181 |
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| Permanent link to this record |
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Author |
Sullivan, E.; Gillie, L.J.; Hadermann, J.; Greaves, C. |
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Title |
Fluorine intercalation in the n=1 and n=2 layered manganites Sr2MnO3.5+x and Sr3Mn2O6 |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Materials research bulletin |
Abbreviated Journal |
Mater Res Bull |
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| |
Volume |
48 |
Issue |
4 |
Pages |
1598-1605 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Fluorine insertion into the oxygen defect superstructure manganite Sr2MnO3.5+x has been shown by transmission electron microscopy (TEM) to result in two levels of fluorination. In the higher fluorine content sections, the fluorine anions displace oxygen anions from their apical positions into the equatorial vacancies, thus destroying the superstructure and reverting to a K2NiF4-type structure (a = 3.8210(1) angstrom and c = 12.686(1) angstrom). Conversely, lower fluorine content sections retain the Sr2MnO3.5+x defect superstructure, crystallising in the P2(1)/c space group. Fluorine intercalation into the reduced double-layer manganite Sr3Mn2O6 occurs in a step-wise fashion according to the general formula Sr3Mn2O6Fy with y = 1, 2, and 3. It is proposed that the y = 1 phase (a = 3.815(1)angstrom, c = 20.29(2) angstrom) is produced by the filling of all the equatorial oxygen vacancies by fluorine atoms whilst the y = 2 phase (a = 3.8222(2) angstrom, c = 21.2435(3)angstrom) has a random distribution of fluorine anions throughout both interstitial rocksalt and equatorial sites. Neutron powder diffraction data suggest that the fully fluorinated y = 3 phase (a = 3.8157(6) angstrom, c = 23.666(4) angstrom) corresponds to the complete occupation of all the equatorial oxygen vacancies and the interstitial sites by intercalated fluorine. (C) 2013 Elsevier Ltd. All rights reserved. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000317544600040 |
Publication Date |
2013-01-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0025-5408; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.446 |
Times cited |
4 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.446; 2013 IF: 1.968 |
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Call Number |
UA @ lucian @ c:irua:108485 |
Serial |
1238 |
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| Permanent link to this record |
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Author |
Hellar-Kihampa, H.; De Wael, K.; Lugwisha, E.; Govindan, M.; Covaci, A.; Van Grieken, R. |
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Title |
Spatial monitoring of organohalogen compounds in surface water and sediments of a rural-urban river basin in Tanzania |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
The science of the total environment |
Abbreviated Journal |
Sci Total Environ |
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Volume |
447 |
Issue |
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Pages |
186-197 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre |
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Abstract |
The presence of persistent organic pollutants in Tanzanian environment is not well monitored despite the existing pollution potential from a number of sources. In this study, we investigated for the first time, the concentration profiles of different organohalogen compounds such as organochlorine pesticide residues (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in environmental samples (water and sediments) from the Pangani river basin (PRB). The PRB is one of the largest drainage basins in Tanzania, with its watershed exposed to multiple input sources of trace organic contaminants. Surface water and sediments were sampled from 12 representative stations of diverse characteristics and land-use practices, in three distinct seasons, and extracted by liquidliquid and Soxhlet extraction methods, respectively. Water samples were analyzed by GC-ECD for OCPs only, while sediment samples were analyzed for OCPs, PCBs and PBDEs by GC/MS. Seven compounds, dominated by HCH isomers (5104460 pg/L) and DDT analogs (1601460 pg/L),were detected in the water samples. These concentrations are far below the WHO guidelines for drinking water quality. A total of 42 compounds (8 OCPs, 28 PCB congeners and 6 PBDE congeners) were detected in the sediment samples. Their respective total concentration ranges were 24510,230; 35711,000 and 382175 pg/g dry weight. The spatial distribution patterns and Hierarchical Cluster Analysis reflected the impact of historical agricultural usage in sugarcane plantations (OCPs), and urbanization (PCBs and PBDEs). Risk assessment using sediment quality guidelines indicated no ecotoxicological risks. The results we have found provide preliminary data on levels of the organic contaminants in Pangani river basin as a new insight on the environmental quality of the area. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000317538100022 |
Publication Date |
2013-02-05 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0048-9697 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.9 |
Times cited |
42 |
Open Access |
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Notes |
; This research project was funded by the International Foundation for Science (IFS, Project Number W/4945-1). The authors wish to acknowledge the contribution of the Pangani Basin Water Office (PBWO) in Moshi, Tanzania; especially Ms. Arafa Maggidi in provision of valuable information and assistance with the sampling campaigns, and Salim Lyimo in mapping of the study area. The contributions of Mr. Peter Machibya of the Department of Geology, University of Dar es Salaam, Tanzania in sediment characterization; and Mr. Emmanuel Gwae, of the Government Chemists Laboratory Agency (GCLA) Dar es Salaam, Tanzania, for instrumental analysis of the water samples, are highly appreciated. Harieth Hellar-Kihampa acknowledges financial support from the Belgian Technical Agency (BTC). Govindan Malarvannan and Adrian Covaci acknowledge financial support from the University of Antwerp. ; |
Approved |
Most recent IF: 4.9; 2013 IF: 3.163 |
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Call Number |
UA @ admin @ c:irua:105260 |
Serial |
5836 |
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| Permanent link to this record |
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Author |
Singh, S.K.; Neek-Amal, M.; Peeters, F.M. |
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Title |
Melting of graphene clusters |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
87 |
Issue |
13 |
Pages |
134103-134109 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Density-functional tight-binding and classical molecular dynamics simulations are used to investigate the structural deformations and melting of planar carbon nanoclusters C-N with N = 2-55. The minimum-energy configurations for different clusters are used as starting configurations for the study of the temperature effects on the bond breaking and rotation in carbon lines (N < 6), carbon rings (5 < N < 19), and graphene nanoflakes. The larger the rings (graphene nanoflakes) the higher the transition temperature (melting point) with ring-to-line (perfect-to-defective) transition structures. The melting point was obtained by using the bond energy, the Lindemann criteria, and the specific heat. We found that hydrogen-passivated graphene nanoflakes (CNHM) have a larger melting temperature with a much smaller dependence on size. The edges in the graphene nanoflakes exhibit several different metastable configurations (isomers) during heating before melting occurs. DOI: 10.1103/PhysRevB.87.134103 |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000317390700001 |
Publication Date |
2013-04-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
28 |
Open Access |
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Notes |
; This work was supported by the EU-Marie Curie IIF Postdoctoral Fellowship No. 299855 (for M.N.-A.), the ESF-EuroGRAPHENE Project CONGRAN, the Flemish Science Foundation (FWO-Vl), and the Methusalem Foundation of the Flemish Government. ; |
Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
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Call Number |
UA @ lucian @ c:irua:108467 |
Serial |
1987 |
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Author |
Muñoz, W.A.; Covaci, L.; Peeters, F.M. |
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Title |
Tight-binding description of intrinsic superconducting correlations in multilayer graphene |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
87 |
Issue |
13 |
Pages |
134509-7 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Using highly efficient GPU-based simulations of the tight-binding Bogoliubov-de Gennes equations we solve self-consistently for the pair correlation in rhombohedral (ABC) and Bernal (ABA) multilayer graphene by considering a finite intrinsic s-wave pairing potential. We find that the two different stacking configurations have opposite bulk/surface behavior for the order parameter. Surface superconductivity is robust for ABC stacked multilayer graphene even at very low pairing potentials for which the bulk order parameter vanishes, in agreement with a recent analytical approach. In contrast, for Bernal stacked multilayer graphene, we find that the order parameter is always suppressed at the surface and that there exists a critical value for the pairing potential below which no superconducting order is achieved. We considered different doping scenarios and find that homogeneous doping strongly suppresses surface superconductivity while nonhomogeneous field-induced doping has a much weaker effect on the superconducting order parameter. For multilayer structures with hybrid stacking (ABC and ABA) we find that when the thickness of each region is small (few layers), high-temperature surface superconductivity survives throughout the bulk due to the proximity effect between ABC/ABA interfaces where the order parameter is enhanced. DOI: 10.1103/PhysRevB.87.134509 |
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Corporate Author |
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Place of Publication |
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Editor |
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Language |
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Wos |
000317390000006 |
Publication Date |
2013-04-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
37 |
Open Access |
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Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem funding of the Flemish Government. ; |
Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
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Call Number |
UA @ lucian @ c:irua:108469 |
Serial |
3660 |
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Author |
Zhang, Q.-Z.; Liu, Y.-X.; Jiang, W.; Bogaerts, A.; Wang, Y.-N. |
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Title |
Heating mechanism in direct current superposed single-frequency and dual-frequency capacitively coupled plasmas |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Plasma sources science and technology |
Abbreviated Journal |
Plasma Sources Sci T |
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Volume |
22 |
Issue |
2 |
Pages |
025014-25018 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
In this work particle-in-cell/Monte Carlo collision simulations are performed to study the heating mechanism and plasma characteristics in direct current (dc) superposed radio-frequency (RF) capacitively coupled plasmas, operated both in single-frequency (SF) and dual-frequency (DF) regimes. An RF (60/2 MHz) source is applied on the bottom electrode to sustain the discharge, and a dc source is fixed on the top electrode. The heating mechanism appears to be very different in dc superposed SF and DF discharges. When only a single source of 60 MHz is applied, the plasma bulk region is reduced by the dc source, thus the ionization rate and hence the electron density decrease with rising dc voltage. However, when a DF source of 60 and 2 MHz is applied, the electron density can increase upon addition of a dc voltage, depending on the gap length and applied dc voltage. This is explained from the spatiotemporal ionization rates in the DF discharge. In fact, a completely different behavior is observed for the ionization rate in the two half-periods of the LF source. In the first LF half-period, the situation resembles the dc superposed SF discharge, and the reduced plasma bulk region due to the negative dc bias results in a very small effective discharge area and a low ionization rate. On the other hand, in the second half-period, the negative dc bias is to some extent counteracted by the LF voltage, and the sheath close to the dc electrode becomes particularly thin. Consequently, the amplitude of the high-frequency sheath oscillations at the top electrode is largely enhanced, while the LF sheath at the bottom electrode is in its expanding phase and can thus well confine the high-energy electrons. Therefore, the ionization rate increases considerably in this second LF half-period. Furthermore, in addition to the comparison between SF and DF discharges and the effect of gap length and dc voltage, the effect of secondary electrons is examined. |
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Corporate Author |
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Thesis |
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Publisher |
Institute of Physics |
Place of Publication |
Bristol |
Editor |
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Language |
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Wos |
000317275400016 |
Publication Date |
2013-03-28 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0963-0252;1361-6595; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.302 |
Times cited |
9 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.302; 2013 IF: 3.056 |
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Call Number |
UA @ lucian @ c:irua:106877 |
Serial |
1413 |
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Author |
Liu, Y.-X.; Zhang, Q.-Z.; Liu, L.; Song, Y.-H.; Bogaerts, A.; Wang, Y.-N. |
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Title |
Electron bounce resonance heating in dual-frequency capacitively coupled oxygen discharges |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Plasma sources science and technology |
Abbreviated Journal |
Plasma Sources Sci T |
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Volume |
22 |
Issue |
2 |
Pages |
025012-11 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The electron bounce resonance heating (BRH) in dual-frequency capacitively coupled plasmas operated in oxygen is studied by different experimental methods and a particle-in-cell/Monte Carlo collision (PIC/MCC) simulation, and compared with the electropositive argon discharge. In comparison with argon, the experimental results show that in an oxygen discharge the resonance peaks in positive-ion density and light intensity tend to occur at larger electrode gaps. Moreover, at electrode gaps L > 2.5 cm, the positive-ion (and electron) density and the light emission drop monotonically in the oxygen discharge upon increasing L, whereas they rise (after an initial drop) in the argon case. At resonance gap the electronegativity reaches its maximum due to the BRH. All these experimental observations are explained by PIC/MCC simulations, which show that in the oxygen discharge the bulk electric field becomes quite strong and is out of phase with the sheath field. Therefore, it retards the resonance electrons when traversing the bulk, resulting in a suppressed BRH. Both experiment and simulation results show that this effect becomes more pronounced at lower high-frequency power, when the discharge mode changes from electropositive to electronegative. In a pure oxygen discharge, the BRH is suppressed with increasing pressure and almost diminishes at 12 Pa. Finally, the driving frequency significantly affects the BRH, because it determines the phase relation between bulk electric field and sheath electric field. |
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Corporate Author |
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Thesis |
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Publisher |
Institute of Physics |
Place of Publication |
Bristol |
Editor |
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Language |
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Wos |
000317275400014 |
Publication Date |
2013-03-18 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0963-0252;1361-6595; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.302 |
Times cited |
20 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.302; 2013 IF: 3.056 |
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Call Number |
UA @ lucian @ c:irua:106534 |
Serial |
911 |
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Author |
Van Laer, K.; Tinck, S.; Samara, V.; de Marneffe, J.F.; Bogaerts, A. |
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Title |
Etching of low-k materials for microelectronics applications by means of a N2/H2 plasma : modeling and experimental investigation |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Plasma sources science and technology |
Abbreviated Journal |
Plasma Sources Sci T |
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Volume |
22 |
Issue |
2 |
Pages |
025011-25019 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
In this paper, we investigate the etch process of so-called low-k organic material by means of a N2/H2 capacitively coupled plasma, as applied in the micro-electronics industry for the manufacturing of computer chips. In recent years, such an organic material has emerged as a possible alternative for replacing bulk SiO2 as a dielectric material in the back-end-of-line, because of the smaller parasitic capacity between adjacent conducting lines, and thus a faster propagation of the electrical signals throughout the chip. Numerical simulations with a hybrid plasma model, using an extensive plasma and surface chemistry set, as well as experiments are performed, focusing on the plasma properties as well as the actual etching process, to obtain a better insight into the underlying mechanisms. Furthermore, the effects of gas pressure, applied power and gas composition are investigated to try to optimize the etch process. In general, the plasma density reaches a maximum near the wafer edge due to the so-called 'edge effect'. As a result, the etch rate is not uniform but will also reach its maximum near the wafer edge. The pressure seems not to have a big effect. A higher power increases the etch rate, but the uniformity becomes (slightly) worse. The gas mixing ratio has no significant effect on the etch process, except when a pure H2 or N2 plasma is used, illustrating the synergistic effects of a N2/H2 plasma. In fact, our calculations reveal that the N2/H2 plasma entails an ion-enhanced etch process. The simulation results are in reasonable agreement with the experimental values. The microscopic etch profile shows the desired anisotropic shape under all conditions under study. |
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Corporate Author |
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Thesis |
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Publisher |
Institute of Physics |
Place of Publication |
Bristol |
Editor |
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Language |
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Wos |
000317275400013 |
Publication Date |
2013-03-18 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0963-0252;1361-6595; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.302 |
Times cited |
13 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.302; 2013 IF: 3.056 |
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Call Number |
UA @ lucian @ c:irua:106654 |
Serial |
1084 |
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| Permanent link to this record |
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Author |
Sahin, H.; Tongay, S.; Horzum, S.; Fan, W.; Zhou, J.; Li, J.; Wu, J.; Peeters, F.M. |
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Title |
Anomalous Raman spectra and thickness-dependent electronic properties of WSe2 |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
87 |
Issue |
16 |
Pages |
165409-6 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Typical Raman spectra of transition-metal dichalcogenides (TMDs) display two prominent peaks, E-2g and A(1g), that are well separated from each other. We find that these modes are degenerate in bulk WSe2 yielding one single Raman peak in contrast to other TMDs. As the dimensionality is lowered, the observed peak splits in two. In contrast, our ab initio calculations predict that the degeneracy is retained even for WSe2 monolayers. Interestingly, for minuscule biaxial strain, the degeneracy is preserved, but once the crystal symmetry is broken by a small uniaxial strain, the degeneracy is lifted. Our calculated phonon dispersion for uniaxially strained WSe2 shows a good match to the measured Raman spectrum, which suggests that uniaxial strain exists in WSe2 flakes, possibly induced during the sample preparation and/or as a result of the interaction between WSe2 and the substrate. Furthermore, we find that WSe2 undergoes an indirect-to-direct band-gap transition from bulk to monolayers, which is ubiquitous for semiconducting TMDs. These results not only allow us to understand the vibrational and electronic properties of WSe2, but also point to effects of the interaction between the monolayer TMDs and the substrate on the vibrational and electronic properties. DOI: 10.1103/PhysRevB.87.165409 |
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Wos |
000317195400007 |
Publication Date |
2013-04-05 |
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ISSN |
1098-0121;1550-235X; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
365 |
Open Access |
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Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem programme of the Flemish government. Computational resources were partially provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). H. S. is supported by the FWO Pegasus Marie Curie Long Fellowship program. ; |
Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
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Call Number |
UA @ lucian @ c:irua:108471 |
Serial |
134 |
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Author |
Liu, Y.; Brelet, Y.; He, Z.; Yu, L.; Mitryukovskiy, S.; Houard, A.; Forestier, B.; Couairon, A.; Mysyrowicz, A. |
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Title |
Ciliary white light : optical aspect of ultrashort laser ablation on transparent dielectrics |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
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Volume |
110 |
Issue |
9 |
Pages |
097601-97605 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We report on a novel nonlinear optical phenomenon, coined as ciliary white light, during laser ablation of transparent dielectrics. It is observed in 14 different transparent materials including glasses, crystals, and polymers. This phenomenon is also universal with respect to laser polarization, pulse duration, and focusing geometry. We interpret its formation in terms of the nonlinear diffraction of the laser generated white light by the ablation crater covered by nanostructures. It carries rich information on the damage profile and morphology dynamics of the ablated surface, providing a real time in situ observation of the laser ablation process. DOI: 10.1103/PhysRevLett.110.097601 |
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New York, N.Y. |
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000317186000007 |
Publication Date |
2013-03-01 |
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0031-9007;1079-7114; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
8.462 |
Times cited |
10 |
Open Access |
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Approved |
Most recent IF: 8.462; 2013 IF: 7.728 |
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Call Number |
UA @ lucian @ c:irua:108509 |
Serial |
360 |
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