117,475 research outputs found
Supporting data set for: Simulations of the Electrochemical Oxidation of Shape-Selected Nanoparticle Catalysts
No full textThis dataset contains input and output files for simulations of the oxidation of a set of shape-selected, 3 nm platinum nanoparticles associated with the manuscript found at https://arxiv.org/abs/2201.07605.
The simulations are performed using a grand-canonical Monte-Carlo algorithm[1,2] in combination with the ReaxFF reactive force field method as implemented in the Amsterdam Density Functional (ADF) software package version 2017.106 by Software for Chemistry and Materials (SCM). The Pt/O ReaxFF force field parameterized by Fantauzzi et al. was used for the simulations.[3] Simulations were performed at oxygen chemical potential conditions corresponding to 200-1000 K at ultra-high vacuum (UHV, pO2 = 10-10 mbar) and 400-1200 K at near-ambient pressure (NAP, pO2 = 1 mbar) conditions. The following nanoparticle shapes were used as input structures for the simulations: (111)-indexed octahedron, (100)-indexed cube, (110)-indexed dodecahedron, (111)- and (100)-indexed cuboctahedron, mixed-indexed sphere, and (730)-indexed tetrahexahedron.
The folder structure is as follows:
Particle shape -> pressure condition -> temperature condition -> simulation input and output files
The simulation input and output files are of the following filetypes:
control: Input parameters for the ReaxFF software.
control_MC: Input parameters for the GCMC subroutine that interacts with the ReaxFF software.
geo: Atomic input coordinates in BGF file format.
geo_MCXXXXXX: Atomic output coordinates in BGF file format and ReaxFF total energy result for GCMC step XXXXXX.
Simulations were performed for a total of 25,000 iterations. Only accepted GCMC steps result in the creation of a geo_XXXXXX output file. Therefore, the index XXXXXX is not continuous since output files are not written at every iteration. Other ReaxFF-specific output has been filtered in order to declutter the dataset.
[1] T. P. Senftle, R. J. Meyer, M. J. Janik, A. C. T. van Duin, J. Chem. Phys. 2013, 139, 044109.
[2] T. P. Senftle, M. J. Janik, A. C. T. van Duin, J. Phys. Chem. C 2014, 118, 4967–4981.
[3] D. Fantauzzi, J. Bandlow, L. Sabo, J. E. Mueller, A. C. T. van Duin, T. Jacob, Phys. Chem. Chem. Phys. 2014, 16, 23118–23133.This work was supported by Deutsche Forschungsgemeinschaft (DFG) through the collaborative research center SFB-1316 as well as the priority program SPP-2080. The state of Baden-Württemberg is acknowledged through bwHCP and DFT through grant no INST 37/935-1 FUGG. The Volkswagen Group Wolfsburg is acknowledged for partial funding, as well as the Icelandic Research Fund. BK acknowledges the University of Iceland Research Fund for funding through a PhD fellowship
X-Ray Photoelectron Spectroscopy (XPS)
No full textX‐ray photoelectron spectroscopy (XPS) is a surface‐sensitive laboratory technique exploited to obtain elemental analysis, chemical state information, and quantitative composition of materials of historical interest in a nondestructive way. The sample has to be stable in ultra‐high vacuum, and limitation on the size requires sometimes an appropriate sampling strategy before XPS analysis. The basics of the technique and some examples of its application to pottery, glass, metals, alloys, and cellulose materials are provided in this brief review, aiming to highlight the possible applications of XPS in the analysis of historical materials, in ascertaining the origin of the degradation of artifacts in order to tailor proper conservation actions
Archaeometric characterization of late Archaic ceramic from Erice (Sicily) aimed to provenance determination
No full textA set of 20 ceramic samples was autoptically selected from the numerous findings recovered from the stratigraphic excavations of the late Archaic city walls of Erice (western Sicily), in order to be analyzed with archaeometric techniques for provenance determination. The excavations were recently carried out as part of a research project funded by the Freie Universiat Berlin and the Fritz Thyssen Foundation. Specifically, the ceramic material consists of tableware with a painted geometric decoration of presumed local/regional production, as well as apparently imported black-glazed pottery. Both the categories can be traced back to a chronological period between the second half/last quarter of the 6th and the beginning of the 5th century BC. The methodological approach was aimed to the characterization of the ceramic pastes in terms of relative abundance, size distribution and mineralogical composition of the aplastic inclusions by the observation of thin sections with the polarizing microscope. The objective of the microscopic observations consisted in verifying the existence of textural and/or mineralogical analogies to be ascribed to the same clayey raw material and, consequently, to the same production centre. The chemical analyses of the same set of ceramic samples were carried out using the ICP-OES and ICP-MS techniques (55 elements in total). The aim of chemical analyses was to verify the adequacy of the petrographic classification and identify any chemical marker useful for provenance determination. All the analyzed samples of painted ceramic with geometric decoration have consistent compositional and textural characteristics, to the point of considering their assignment to a single 'paste group'. Specifically, it was found the use of very peculiar clay rich in calcareous bioclasts among the included aplastic and relatively poor in quartz and mica. The production, well distinguishable from those to date already attested in western Sicily, could be local. Concerning samples taken from the ceramic fragments decorated with black glaze, the evidence derived from mineralogical-petrographic observations and chemical analyses help confirm their importation from extra-insular production centres, specifically from the Attic region. The Ca-poor paste and the peculiar concentration of many trace elements such as Cr, Ni, Co, As, Pb, Zn, Cu, Sc, Be, V, Ga, Ge, Sn, Tl in the ceramic body strongly support this hypothesis
An Innovative Lens Type FinLine to Microstrip Transition
No full textDue to the disadvantages of vacuum tubes in terms of warm-up time, size, and highvoltage
needs, solid-state power amplifiers (SSPAs) with gallium nitride (GaN)
monolithic microwave integrated circuits (MMICs) are the key solution for power
levels up to some kilowatts in continuous wave. An SSPA is the most convenient
solution for these RF power levels due to its low weight, small size, negligible
warm-up time, low-voltage operation, and high reliability. Spatial power amplifiers
(SPAs) combining techniques are the best candidates for SSPAs due to the intrinsic
low attenuation in dividing and combining functions. SPAs mainly use two types
of probes: transverse and longitudinal, such as FinLines. This paper describes a
broadband FinLine to microstrip (FLuS) transition based on dielectric lens theory.
Comparative simulations with traditional FinLine transitions show a significant
improvement in matching performances and a very significant increase in mechanical
resistance of the transition. The proposed innovative FLuS uses a substrate shaping
designed according to dielectric lens theory. Frequency simulations of a FLuS
inside the WR22 waveguide are shown. These evidence the better performances
of this transition than the classic FLuS transition using quarter-wave transformer
(QWT) matching. A Q band spatial power combiner with dielectric lens FLuS was
made and measured, showing the excellent performances of this innovative FLuS
transition
High Power Density Spatial Combiner for the Q-Band, Ready for Space Applications
No full textThis paper outlines the design characterization and electromagnetic performance of
a millimeter-wave high power combining structure, which exploits the spatial power combination
technique. The input matching is always below 10 dB over the entire Q band, and the overall weight
of the structure is about 500 g. Multiphysics simulations show how this structure is suitable for the
most challenging space missions that will arise in next few years. In fact, 100W of RF power above
the frequency of 40 GHz can be delivered while all the specications for satellite payloads are complied.
Other Spatial Power Combiner structures, such as Radial ones, cannot be implemented in space missions
since they are much less compact and much heavier than the one presented in this article, and this is
the major advantage of this conguration which was specially designed for a space project
Virtual prototype of innovative ka-band power amplifier based on waveguide polarizer
No full textThis paper outlines an innovative approach to design a spatial power-combining structure
based on waveguide polarizers. It presents the 3D CAD model of the new structure with the transversal
probes and considerations in positioning and optimization of them. Exploiting the transformation of the
dominant input mode TE10 into an elliptically polarized wave, provided by the polarizer, it has been
possible to achieve a division of power by eight, completely carried out in space. With the insertion of the
transversal probes made by microstrips, the RF signal can be sent to the MMIC solid state power amplifiers,
and then recombined in the output section. Thanks to the large number of power divisions made in the
waveguide section, the insertion loss of the power divider/combiner is less than 0.5 dB across the 32-34
GHz band, achieving a great power density as well. At the authors’ best knowledge, this is the first work
where a waveguide polarizer is used in Spatial Power Combining technology
Le Plectre : publication musicale / directeur artistique L. Fantauzzi
No full text01 juin 19241924/06/01 (A21,N194).Appartient à l’ensemble documentaire : PACA
Le Plectre : publication musicale / directeur artistique L. Fantauzzi
No full text01 mai 19271927/05/01 (A24,N229).Appartient à l’ensemble documentaire : PACA
Le Plectre : publication musicale / directeur artistique L. Fantauzzi
No full text01 octobre 19241924/10/01 (A21,N198).Appartient à l’ensemble documentaire : PACA
Le Plectre : publication musicale / directeur artistique L. Fantauzzi
No full text01 juillet 19051905/07/01 (A3,N21).Appartient à l’ensemble documentaire : PACA
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