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Author |
Khalilov, U.; Pourtois, G.; van Duin, A.C.T.; Neyts, E.C. |
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Title |
Self-limiting oxidation in small-diameter Si nanowires |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
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Volume |
24 |
Issue |
11 |
Pages |
2141-2147 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Recently, core shell silicon nanowires (Si-NWs) have been envisaged to be used for field-effect transistors and photovoltaic applications. In spite of the constant downsizing of such devices, the formation of ultrasmall diameter core shell Si-NWs currently remains entirely unexplored. We report here on the modeling of the formation of such core shell Si-NWs using a dry thermal oxidation of 2 nm diameter (100) Si nanowires at 300 and 1273 K, by means of reactive molecular dynamics simulations using the ReaxFF potential. Two different oxidation mechanisms are discussed, namely a self-limiting process that occurs at low temperature (300 K), resulting in a Si core I ultrathin SiO2 silica shell nanowire, and a complete oxidation process that takes place at a higher temperature (1273 K), resulting in the formation of an ultrathin SiO2 silica nanowire. The oxidation kinetics of both cases and the resulting structures are analyzed in detail. Our results demonstrate that precise control over the Si-core radius of such NWs and the SiOx (x <= 2.0) oxide shell is possible by controlling the growth temperature used during the oxidation process. |
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Place of Publication |
Washington, D.C. |
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Language |
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Wos |
000305092600021 |
Publication Date |
2012-05-18 |
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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 |
0897-4756;1520-5002; |
ISBN |
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Additional Links  |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
9.466 |
Times cited |
45 |
Open Access |
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Notes |
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Approved |
Most recent IF: 9.466; 2012 IF: 8.238 |
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Call Number |
UA @ lucian @ c:irua:99079 |
Serial |
2976 |
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Author |
Neyts, E.C.; Thijsse, B.J.; Mees, M.J.; Bal, K.M.; Pourtois, G. |
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Title |
Establishing uniform acceptance in force biased Monte Carlo simulations |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Journal of chemical theory and computation |
Abbreviated Journal |
J Chem Theory Comput |
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Volume |
8 |
Issue |
6 |
Pages |
1865-1869 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Uniform acceptance force biased Monte Carlo (UFMC) simulations have previously been shown to be a powerful tool to simulate atomic scale processes, enabling one to follow the dynamical path during the simulation. In this contribution, we present a simple proof to demonstrate that this uniform acceptance still complies with the condition of detailed balance, on the condition that the characteristic parameter lambda = 1/2 and that the maximum allowed step size is chosen to be sufficiently small. Furthermore, the relation to Metropolis Monte Carlo (MMC) is also established, and it is shown that UFMC reduces to MMC by choosing the characteristic parameter lambda = 0 [Rao, M. et al. Mol. Phys. 1979, 37, 1773]. Finally, a simple example compares the UFMC and MMC methods. |
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Wos |
000305092400002 |
Publication Date |
2012-05-16 |
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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 |
1549-9618;1549-9626; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.245 |
Times cited |
20 |
Open Access |
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Notes |
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Approved |
Most recent IF: 5.245; 2012 IF: 5.389 |
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Call Number |
UA @ lucian @ c:irua:99090 |
Serial |
1082 |
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Author |
Scarrozza, M.; Pourtois, G.; Houssa, M.; Heyns, M.; Stesmans, A. |
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Title |
Oxidation of the GaAs(001) surface : insights from first-principles calculations |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
85 |
Issue |
19 |
Pages |
195307-195307,8 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We performed a detailed investigation of the oxidation of the technologically relevant GaAs(001)-beta 2(2x4) surface via density functional calculations. The purpose is to gain insights on the atomistic mechanisms and local bondings that underlie the degradation of the surface properties once exposed to oxygen. The study comprises the adsorption of single O atoms, through the sampling of several adsorption sites, and the subsequent formation of the O adsorbate at increasing coverage by taking into account multiple-atom adsorption. Based on the evaluation of the energetics and the structural properties of the atomistic models generated, the results here reported delineate a consistent picture of the initial stage of the surface oxidation: (i) at low coverage, in the limit of single O insertions, oxygen is incorporated on the surface forming a twofold-bridging Ga-O-As bond; (ii) at increasing coverage, as multiple O atoms are involved, this is accompanied by the formation of a threefold-coordinated bond (with two Ga and one As atoms); (iii) the latter has important implications regarding the electronic properties of the adsorbate since this O bonding may result in the formation of As dangling bonds. Moreover, a clear trend of increased energy gain for the incorporation of neighboring O atoms compared to single O insertions indicates that the formation of oxide clusters is favored over a regime of uniform oxidation. Our findings provide a detailed description of the O bonding and stress the importance of modeling the adsorption of multiple O atoms for an accurate description of the surface oxidation. |
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Place of Publication |
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Wos |
000303755700006 |
Publication Date |
2012-05-08 |
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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 |
15 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
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Call Number |
UA @ lucian @ c:irua:99122 |
Serial |
2538 |
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Author |
Tinck, S.; Bogaerts, A. |
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Title |
Modeling SiH4/O2/Ar inductively coupled plasmas used for filling of microtrenches in shallow trench isolation (STI) |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Plasma processes and polymers |
Abbreviated Journal |
Plasma Process Polym |
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Volume |
9 |
Issue |
5 |
Pages |
522-539 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Modeling results are presented to gain a better insight in the properties of a SiH4/O2/Ar inductively coupled plasma (ICP) and how it interacts with a silicon substrate (wafer), as applied in the microelectronics industry for the fabrication of electronic devices. The SiH4/O2/Ar ICP is used for the filling of microtrenches with isolating material (SiO2), as applied in shallow trench isolation (STI). In this article, a detailed reaction set that describes the plasma chemistry of SiH4/O2/Ar discharges as well as surface processes, such as sputtering, oxidation, and deposition, is presented. Results are presented on the plasma properties during the plasma enhanced chemical vapor deposition process (PECVD) for different gas ratios, as well as on the shape of the filled trenches and the surface compositions of the deposited layers. For the operating conditions under study it is found that the most important species accounting for deposition are SiH2, SiH3O, SiH3 and SiH2O, while SiH+2, SiH+3, O+2 and Ar+ are the dominant species for sputtering of the surface. By diluting the precursor gas (SiH4) in the mixture, the deposition rate versus sputtering rate can be controlled for a desired trench filling process. From the calculation results it is clear that a high deposition rate will result in undesired void formation during the trench filling, while a small deposition rate will result in undesired trench bottom and mask damage by sputtering. By varying the SiH4/O2 ratio, the chemical composition of the deposited layer will be influenced. However, even at the highest SiH4/O2 ratio investigated (i.e., 3.2:1; low oxygen content), the bulk deposited layer consists mainly of SiO2, suggesting that low-volatile silane species deposit first and subsequently become oxidized instead of being oxidized first in the plasma before deposition. Finally, it was found that the top surface of the deposited layer contained less oxygen due to preferential sputtering of O atoms, making the top layer more Si-rich. However, this effect is negligible at a SiH4/O2 ratio of 2:1 or lower. |
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Publisher |
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Place of Publication |
Weinheim |
Editor |
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Language |
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Wos |
000303858100010 |
Publication Date |
2012-03-06 |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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ISSN |
1612-8850; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.846 |
Times cited |
5 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.846; 2012 IF: 3.730 |
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Call Number |
UA @ lucian @ c:irua:99127 |
Serial |
2142 |
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Author |
Bleiner, D.; Belloni, F.; Doria, D.; Lorusso, A.; Nassisi, V. |
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Title |
Overcoming pulse mixing and signal tailing in laser ablation inductively coupled plasma mass spectrometry depth profiling |
Type |
A1 Journal article |
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Year |
2005 |
Publication |
Journal of analytical atomic spectrometry |
Abbreviated Journal |
J Anal Atom Spectrom |
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Volume |
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Issue |
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Pages |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The laser ablation-induced plasma was used as a composition-con trolled source for ion implantation in Si crystals. Then, laser ablation in combination with inductively coupled plasma mass spectrometry was used for the elemental depth profiling of the implanted samples. Monte Carlo simulations permitted us to conclude that a depth resolution of tens of nm would be necessary to define the shape of the implantation profiles, as is obtained using XPS and RBS, whereas a hundred nm depth resolution is sufficient to determine the total implanted dose. The detection power of LA-ICP-MS would routinely allow rapid analytical control on the trace level implanted dose. Nevertheless, this technique is limited in terms of depth profiling resolution due to pulse mixing and signal tailing induced during the aerosol transport. Raw signal processing procedures were developed for the minimization of shapeline dispersion, deconvolution of pulse mixing and more appropriate assessment of the implanted profiles. Shapeline dispersion could be corrected for by determining the signal waning constant and implementing this information for a non-affine alibi transformation of the LA-ICP-MS signal traces. Pulse mixing deconvolution was attained with an algorithm that considered accumulated signal intensity due to pulse-on-pulse stacking, i.e., the latest pulse on top of all antecedent individual pulses' exponential tails proportionally. |
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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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Wos |
000233958900018 |
Publication Date |
2005-10-10 |
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Series Editor |
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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 |
0267-9477 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.379 |
Times cited |
26 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.379; 2005 IF: 3.640 |
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Call Number |
UA @ lucian @ c:irua:99278 |
Serial |
4525 |
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Author |
Bleiner, D.; Altorfer, H. |
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Title |
A novel gas inlet system for improved aerosol entrainment in laser ablation inductively coupled plasma mass spectrometry |
Type |
A1 Journal article |
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Year |
2005 |
Publication |
Journal of analytical atomic spectrometry |
Abbreviated Journal |
J Anal Atom Spectrom |
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Volume |
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Issue |
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Pages |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
In order to minimize the dead volume in large cells for laser ablation inductively coupled plasma mass spectrometry, and improve the aerosol entrainment characteristics, the gas inlet nozzle has been set in rotation. This allowed a wider volume to be swept than with the traditional static inlet nozzle approach. Therefore, sensitivity combined with site-to-site repeatability was improved by a factor of two, together with minimization of aerosol loss within the cell and signal dispersion. |
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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 |
000231246900013 |
Publication Date |
2005-07-01 |
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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 |
0267-9477 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.379 |
Times cited |
21 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.379; 2005 IF: 3.640 |
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Call Number |
UA @ lucian @ c:irua:99309 |
Serial |
4524 |
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