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Study of the mechanical behaviour and self-cementing properties of recycled crushed concrete aggregates
Published in Inge Hoff, Helge Mork, Rabbira Garba Saba, Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 3, 2022
C. Wang, C. Chazallon, S. Mouhoubi, P. Hornych, P. Jing
Figure 6 shows the permanent axial strain ε1p evolution of RCA materials after different curing time. Since self-cementing properties of ORCA have a negligible cementation effect on permanent deformation, NRCA were cured for 180 days instead of 28 days. Each ε1p represents the mean value of two or three specimens. Since all the testing parameters, such as particle size distribution, water content (optimum moisture content minus 1%) and dry density (maximum dry density at the targeted water content) are the same for both RCA materials, the ORCA and NRCA curing for 1 day have the similar ε1p, as shown in Figure 6. After curing 28 days, ORCA presents a similar level of the ε1p compared with that of ORCA curing for 1 day. In contrast, the ε1p of NRCA is much lower after curing for 180 days. The decrease of ε1p is attributed to the presence of unhydrated cement in the NRCA and decreased water content. The results indicate that the influence of self-cementing properties on permanent deformation of NRCA is significant.
Synthesis and biological activity of iron(II), iron(III), nickel(II), copper(II) and zinc(II) complexes of aliphatic hydroxamic acids
Published in Journal of Coordination Chemistry, 2023
Ibrahima Sory Sow, Michel Gelbcke, Franck Meyer, Marie Vandeput, Mickael Marloye, Sergey Basov, Margriet J. Van Bael, Gilles Berger, Koen Robeyns, Sophie Hermans, Dong Yang, Véronique Fontaine, François Dufrasne
X-ray diffraction data were collected on a MAR345 image plate detector (Hamburg, Germany) using Mo Kα radiation generated by a Rigaku Ultra X18S rotating anode (Tokyo, Japan). Crystals for structure determination were obtained for the Fe(III) complexes, giving red-orange plate like crystals after evaporation of a MeOH/DCM solution (1: 9). The collected images were integrated and reduced by CrysAlisPRO and the implemented absorption correction was applied. Structure was solved by SHELXT and refined by full-matrix least squares against F2 using SHELXL 2014/7. Quantum mechanical methods for density functional theory (DFT) calculations have been achieved using Orca 4.2.1 [33], performed in the gas phase. Geometries were fully optimized with the triple-ζ quality, low-cost method B97-3c from Grimme and co-workers [34]. Potential energy surface minima found upon optimization were confirmed by frequency calculations and free energies were corrected to account for the zero-point energy. Optimized geometries were verified as minima (i.e. no imaginary frequencies).
Synthesis, characterization, and crystal structure analysis of group IIB coordination compounds containing N,N′-bidentate chelating Schiff-base ligand
Published in Journal of Coordination Chemistry, 2020
Taraneh Hajiashrafi, Roghayeh Zekriazadeh, Maciej Kubicki
Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations of the non-covalent interactions were carried out using the ORCA quantum chemistry suite [30]. The BLYP exchange-correlation functional [31] with the recent D3 empirical dispersion correction (BLYP-D3) was used to evaluate the binding energies [32]. The basis set superposition error (BSSE) is not taken into consideration because small BSSE effects are assumed to be absorbed by the D3 empirical potential [33]. The decomposition of the interaction binding energy was also computed at BLYP-D3/TZ2P. To evaluate the interactions in the solid-state, we used the crystallographic coordinates. This procedure and level of the theory have been successfully used to evaluate similar interactions [18, 34, 35]. An all-electron triple-zeta basis-set with two polarization functions, TZ2P, was used to describe all the atoms. The core electrons were treated by using a frozen core approximation. The zeroth-order regular approximation (ZORA) was applied for treating relativistic effect.
Calculation of liquidus curve in phase diagram LiCl-KCl by molecular dynamics simulation
Published in Phase Transitions, 2020
M. A. Kobelev, A. S. Tatarinov, D. O. Zakiryanov, N. K. Tkachev
The pair interaction in an ionic system is chosen to have the form of the Born–Mayer potential, which consists of the Coulomb term and short-range Born repulsion:where and are the valencies of the ions, is the distance between ions, is the dielectric constant (equal to 1 in further calculations), is the elementary charge. The parameters and were calculated ab initio. The single-point calculations were performed in ORCA program [14] within the framework of the second-order Møller-Plesset perturbation theory to obtain potential energy curves. In Figure 1, the results of ab initio calculations of the LiCl pair are presented together with the fitted Born–Mayer curve. Table 1 shows the calculated Born repulsion parameters for all pairs of ions in the LiCl-KCl mixture.