Showing 1–4 of 4 results for author: Shaker, M

The effect of graphene orientation on permeability and corrosion initiation under composite coatings

Authors: Majid Shaker, Erfan Salahinejad, Weiqi Cao, Xiaomin Meng, Vahdat Zahedi Asl, Qi Ge

Abstract: The unique anisotropic properties of graphene, particularly impermeability, have made it a promising candidate for further advances in corrosion prevention applications. Despite the large number of experimental works divulging the use of graphene in anticorrosion coatings, there is no report on the numerical modelling and simulation of the relationships between the orientation of graphene sheets i… ▽ More The unique anisotropic properties of graphene, particularly impermeability, have made it a promising candidate for further advances in corrosion prevention applications. Despite the large number of experimental works divulging the use of graphene in anticorrosion coatings, there is no report on the numerical modelling and simulation of the relationships between the orientation of graphene sheets in composite coatings and the introduced corrosion protection efficiency, to our knowledge. Herein, it is tried to model the influence of the orientation of graphene sheets dispersed in organic coatings on the diffusivity and flux of corrosive substances besides the corrosion initiation time of the protected substrates. To discover the relationship between the graphene orientation and corrosion-related phenomena, this study introduces a novel model consisting of a trigonometric factor named unprotected projected surface area proportion, which calculates corrosion-related parameters based on the principal Fick's laws. The model reveals that the decrease in the angle between graphene sheets and the substrate is highly beneficial for postponing the corrosion onset. It is accordingly estimated that a mismatch angle of 10 degree can slow down the diffusion process significantly and delay the corrosion initiation by around 65 times in a 100 micron thick epoxy/graphene composite coating in comparison to the counterpart with the perpendicular alignment. The predicted corrosion parameters were in a good agreement with the experimental data, indicating the merit of the proposed model. Thus, this model can be further employed as the fundamental of future research on the optimum graphene orientation in anticorrosion composite coatings. △ Less

Submitted 2 February, 2026; originally announced February 2026.

Journal ref: Construction and Building Materials, 319 (2022) 126080

A combined criterion of surface free energy and roughness to predict the wettability of non-ideal low-energy surfaces

Authors: Majid Shaker, Erfan Salahinejad

Abstract: The significance of wettability between solid and liquid substances in different fields encourages scientists to develop accurate models to estimate the resultant apparent contact angles. Surface free energy (SFE), which is principally defined for ideal (flat) surfaces, is not applicable to predict the wettability of real (rough) surfaces. This paper introduces a new parameter, namely normalized s… ▽ More The significance of wettability between solid and liquid substances in different fields encourages scientists to develop accurate models to estimate the resultant apparent contact angles. Surface free energy (SFE), which is principally defined for ideal (flat) surfaces, is not applicable to predict the wettability of real (rough) surfaces. This paper introduces a new parameter, namely normalized surface free energy (NSFE) as a combination of SFE and roughness, to predict the contact angle of liquids on non-ideal low-energy surfaces. The remarkable consistency of the predicted and measured contact angles of liquids on some rough surfaces also confirm the validity of the approach. △ Less

Submitted 23 January, 2026; originally announced January 2026.

Journal ref: Progress in Organic Coatings, 119 (2018) 123-126

Decoding Shake-up Satellites in XPS through Large-Scale ab initio Simulations: Spectral Signatures of Ring Fusion in Porphyrins

Authors: Jannis Kockläuner, Majid Shaker, Maximilian Muth, Simon Steinbach, Christoph Oleszak, Ole Lytken, Hans-Peter Steinrück, Dorothea Golze

Abstract: In X-ray photoelectron spectroscopy (XPS), shake-up satellites arise when core ionization is accompanied by simultaneous charge-neutral valence excitations. Although these satellites can contain detailed structural information, they are rarely interpreted due to the lack of accurate and scalable theoretical methods. Here, we develop and apply a many-body perturbation theory framework within the… ▽ More In X-ray photoelectron spectroscopy (XPS), shake-up satellites arise when core ionization is accompanied by simultaneous charge-neutral valence excitations. Although these satellites can contain detailed structural information, they are rarely interpreted due to the lack of accurate and scalable theoretical methods. Here, we develop and apply a many-body perturbation theory framework within the $GW$ plus cumulant ($GW+C$) approach that enables accurate predictions of shake-up satellites in large molecular systems. For unfused, mono-fused, and doubly fused porphyrin derivatives with up to 170 atoms, we achieve excellent agreement with experiment, reproducing both main photoionization signals and satellite features within $0.2-0.3$ eV. We show that ring fusion strongly affects satellite features, whereas the N 1s photoionization signals remain unchanged. Our calculations reveal the mechanism behind these changes, identifying the spatial localization of valence excitations as the driving force. This work not only deepens understanding of the shake-up mechanism in porphyrins but also shows how predictive computations can unlock the chemical information encoded in satellites. △ Less

Submitted 30 September, 2025; originally announced September 2025.

Applications of the Variational Monte Carlo Method to the Ground States of the Lithium Atom and its Ions up to Z = 10 in the Presence of Magnetic Field

Authors: S. B. Doma, M. O. Shaker, A. M. Farag, F. N. El-Gammal

Abstract: The variational Monte Carlo method is applied to investigate the ground state energy of the lithium atom and its ions up to Z=10 in the presence of an external magnetic field regime with γ=0 ~ 100 a.u. Our calculations are based on using three forms of compact and accurate trial wave functions, which were put forward in calculating energies in the absence of magnetic field. The obtained results ar… ▽ More The variational Monte Carlo method is applied to investigate the ground state energy of the lithium atom and its ions up to Z=10 in the presence of an external magnetic field regime with γ=0 ~ 100 a.u. Our calculations are based on using three forms of compact and accurate trial wave functions, which were put forward in calculating energies in the absence of magnetic field. The obtained results are in good agreement with the most recent accurate values and also with the exact values. △ Less

Submitted 19 February, 2016; v1 submitted 12 February, 2016; originally announced February 2016.

Comments: 12 pages. arXiv admin note: substantial text overlap with arXiv:physics/9801014 by other authors; text overlap with arXiv:1010.4992 by other authors