Metric structures in L_1: Dimension, snowflakes, and average distortion

We study the metric properties of finite subsets of L_1. The analysis of such metrics is central to a number of important algorithmic problems involving the cut structure of weighted graphs, including the Sparsest Cut Problem, one of the most compelling open problems in the field of approximation algorithms. Additionally, many open questions in geometric non-linear functional analysis involve the properties of finite subsets of L_1.Comment: 9 pages, 1 figure. To appear in European Journal of Combinatorics. Preliminary version appeared in LATIN '0

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Impact of initial surface passivation on wetting properties analysis during III-V/Si epitaxy

International audienceThe co-integration of III-V semiconductors on Si (001) substrates is highly desirable for energy harvesting, electronics, and photonic applications. [1-3] Understanding surface passivation prior to any heterogeneous integration of materials through epitaxy is a cornerstone to establish the wetting characteristics in a material system. [4] Using DFT simulations, we highlight how to quantitatively determine the impact of Si surface passivation prior to III-V/Si hetero-epitaxy on the surface energy of the Si initial substrate. Then, we explore its consequences for the description of wetting properties on the specific case of GaP/Si heterogeneous growth. [5] We show that this inevitable passivation on Si prior to GaP/Si heteroepitaxy leads to a large decrease of the substrate surface energy. This, in turn, leads to a significant decrease in the spreading parameter for the studied system. In addition, we demonstrate that the stabilization of the initial Si surface through passivation is a driving force for 3D Volmer-Weber crystal growth. Finally, it is established that a complete wetting situation would become possible if the passivated Si surface could be destabilized by at least 15 meV/Ų or if the III-V (001) surface could be stabilized by the same amount.This research was supported by the French National Research NUAGES Project (Grant no. ANR-21-CE24-0006). DFT calculations were performed at FOTON Institute, and the work was granted access to the HPC resources of TGCC/CINES under the allocation A0120911434 and A0140911434 made by GENCI.[1] I. Lucci, S. Charbonnier, L. Pedesseau, M. Vallet, L. Cerutti, J.-B. Rodriguez, E. Tournié, R. Bernard, A. Létoublon, N. Bertru, A. Le Corre, S. Rennesson, F. Semond, G. Patriarche, L. Largeau, P. Turban, A. Ponchet, and C. Cornet, Phys. Rev. Materials 2(6), 060401 (2018).[2] I. Lucci, S. Charbonnier, M. Vallet, P. Turban, Y. Léger, T. Rohel, N. Bertru, A. Létoublon, J. Rodriguez, L. Cerutti, E. Tournié, A. Ponchet, G. Patriarche, L. Pedesseau, and C. Cornet, Adv Funct Materials 28(30), 1801585 (2018).[3] C. Cornet, S. Charbonnier, I. Lucci, L. Chen, A. Létoublon, A. Alvarez, K. Tavernier, T. Rohel, R. Bernard, J.-B. Rodriguez, L. Cerutti, E. Tournié, Y. Léger, M. Bahri, G. Patriarche, L. Largeau, A. Ponchet, P. Turban, and N. Bertru, Phys. Rev. Materials 4(5), 053401 (2020).[4] S. Pallikkara Chandrasekharan, I. Lucci, D. Gupta, C. Cornet, and L. Pedesseau, Phys. Rev. B 108(7), 075305 (2023).[5] S. Pallikkara Chandrasekharan, D. Gupta, C. Cornet, and L. Pedesseau, Phys. Rev. B 109(4), 045304 (2024)

Determination of Gold by Inductively Coupled Plasma Optical Emission Spectrometry

Fire assay is the most common technique for the determination of the precious metals in rock and ore samples. The technique is generally accurate in most circumstances for the determination of gold. However, with the development of modern laboratory techniques like ICP-OES, GD-OES, alternative methods have become available which may offer the advantage of rapid determination of small concentrations of gold. A simple analytical method for the determination of gold in ore samples using ICP-OES is reported. A multi-parametric linear regression model was used to eliminat e the observed interelemental inter-ferences and the gold content in ores was estimated using this mode

Impact of surface passivation of III-V elements on Si (001) substrate based on absolute surface and barrier energy calculations

International audienceConsidering the cheap and larger substrate advantages offered by standard Si industrial processes, the integration of III-V compound semiconductors on Si (001) substrates is a way of dramatically reducing the manufacturing cost of many devices. Elucidation of surface passivation is one of the key parameters during wetting-property studies and heterogeneous epitaxy, as it fundamentally controls the growth and physical properties of composite materials and devices for photonics, electronics, or energy harvesting applications [1-3] . In this work, with the use of Density Functional Theory (DFT), we analyze the surface passivation behavior of H and III-Vs on Si by determining the absolute surface energies, and barrier energies (using nudged elastic band method). This approach is anticipated to be useful for numerous different associations of surface passivation [3,4] . We finally provide quantitative evidence using DFT simulations that the nature of monoatomic layer that forms on the substrate surface can have a significant impact on the general description of surface passivation as well as the wetting-properties and epitaxial growth of the III-V semiconductor heterostructure on Si.[1] I. Lucci et al., Physical Review Materials 2 (6), 060401 (R), (2018).[2] I. Lucci et al., Advanced Functional Materials, 28(30):1801585, (2018).[3] L. Pedesseau et al., arXiv preprint arXiv:2303.15566 (2023).[4] C. Cornet et al., Phys. Rev. Mater. 4, 053401 (2020)