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1.
Kaishuo Yang Ehsan Sadeghi Pouya Libin Liu Dr. Ming Li Dr. Xiaoxian Yang Dr. Neil Robinson Prof. Eric F. May Prof. Michael L. Johns 《Chemphyschem》2022,23(4):e202100794
Understanding the behaviour of short-chain hydrocarbons confined to porous solids informs the targeted extraction of natural resources from geological features, and underpins rational developments in separation, storage and catalytic conversion processes. Herein, we report the application of low-field (12.7 MHz) 1H nuclear magnetic resonance (NMR) relaxation measurements to characterise ethane dynamics within mesoporous silica materials exhibiting mean pore diameters between 6 and 50 nm. Our measurements provide NMR-based adsorption isotherms within the range 25–50 bar and at ambient temperature, incorporating the ethane condensation point (40.7 bar at our experimental temperature of 23.6 °C). The quantitative nature of the acquired data is validated via a direct comparison of NMR-derived excess adsorption capacities with ex situ gravimetric ethane adsorption measurements, which are demonstrated to agree to within 0.2 mmol g−1 of the observed ethane capacity. NMR relaxation time distributions are further demonstrated as a means to decouple interparticle and mesopore dominated adsorption phenomena, with unexpectedly rapid relaxation rates associated with interparticle ethane gas confirmed via a direct comparison with NMR self-diffusion analysis. 相似文献
2.
Elnaz Khalilzadeh Amir Chakhmachi Behrouz Maraghechi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2015,69(11):256
The influence of self-fields on the cyclotron maser instability in a hollow electron beam propagating parallel to a uniform axial magnetic field B 0 ê z in a dielectric loaded waveguide is investigated. The theoretical analysis is carried out within the framework of linearized Vlasov-Maxwell equations. It is assumed that the beam is thin with the radial thickness much smaller than the beam radius. A new dispersion relation for azimuthally symmetric electromagnetic perturbation is derived and analyzed numerically. The influence of self-fields on the cyclotron maser instability in a dielectric loaded waveguide for different dielectric medium is studied. It is found that unlike the hollow waveguide the growth rate is increased by increasing self-fields. The instability band width decreases due to the increasing self-fields. The maximum growth rate increases gradually as self-fields increase as regards a different dielectric medium. 相似文献
3.
Tofighi-Niaki Ebrahim Asgharifard-Sharabiani Pouya Ahmadian Hamid 《Nonlinear dynamics》2018,94(4):2937-2956
Nonlinear Dynamics - Rub–impact phenomenon occurring in hydrodynamic journal bearings is one of the main malfunctions in rotating machines and causes undesirable dynamic behavior. In order to... 相似文献
4.
Shahram Pouya Manoochehr Koochesfahani Preston Snee Moungi Bawendi Daniel Nocera 《Experiments in fluids》2005,39(4):784-786
We introduce the use of quantum dot (QD) nanoparticles for near-surface velocimetry and provide preliminary data to demonstrate its feasibility. Evanescent wave illumination is used to image the motion of water-soluble (CdSe)ZnS QDs with a core size of 6 nm within a region of order 100 nm of a surface . Results are presented for the two in-plane components of the velocity field. 相似文献
5.
Improved parameterization of the quantum harmonic oscillator model based on localized wannier functions to describe Van der Waals interactions in density functional theory 下载免费PDF全文
Pouya Partovi‐Azar Matthias Berg Simone Sanna Thomas D. Kühne 《International journal of quantum chemistry》2016,116(15):1160-1165
Recently, the quantum harmonic oscillator model has been combined with maximally localized Wannier functions to account for long‐range dispersion interactions in density functional theory calculations (Silvestrelli, J. Chem. Phys. 2013, 139, 054106). Here, we present a new, improved set of values for the three parameters involved in this scheme. To test the new parameter set we have computed the potential energy curves for various systems, including an isolated Ar2 dimer, two N2 dimers interacting within different configurations, and a water molecule physisorbed on pristine graphene. While the original set of parameters generally overestimates the interaction energies and underestimates the equilibrium distances, the new parameterization substantially improves the agreement with experimental and theoretical reference values. © 2016 Wiley Periodicals, Inc. 相似文献
6.
Shahram Pouya Alexander Van Rhijn Marcos Dantus Manoochehr Koochesfahani 《Experiments in fluids》2014,55(8):1-5
We present results for first molecular tagging velocimetry (MTV) measurements in water under resonant femtosecond excitation/emission process of a phosphorescent supramolecule. Both two-photon and three-photon absorption processes are examined, and the feasibility of measurements is demonstrated by single component velocimetry in a simple jet flow. The new capabilities enabled by FemtoMTV include elimination of the need for short wavelength UV excitation source and UV optical access in flow facilities, and potential for high rep-rate flow imaging. 相似文献
7.
The equations governing plane steady-state flow in heterogeneous porous body containing cracks are presented first. Then,
a general transformation lemma is presented which allows extending a particular solution obtained for a given flow problem
to another configuration with different geometry, behaviour and boundary conditions. An existing potential solution in terms
of discharges along the cracks, established by Liolios and Exadaktylos (J Solids Struct 43:3960–3982, 2006) for non-intersecting
cracks in isotropic matrix, is extended to intersecting cracks in anisotropic matrix. The basic problem of a single straight
crack in an infinite body submitted to a pressure gradient at infinity is then investigated and a closed-form solution is
presented for the case of void cracks (infinite conductivity), as well as a semi-analytical solution for the case of cracks
with Poiseuille type conductivity. These solutions, derived first for an isotropic matrix, are then extended to anisotropic
matrices using the general transformation lemma. Finally, using the solution obtained for a single crack, a closed-form estimation
of the effective permeability of micro-cracked porous materials with weak crack density is derived from a self-consistent
upscaling scheme. 相似文献
8.
Ahmad Pouya 《European Journal of Mechanics - A/Solids》2000,19(6):1015
Rock salt is considered as a pure aggregate of halite (mineral NaCl) crystals and its behaviour is investigated by a micro–macro approach. The behaviour of the polycrystalline aggregate is deduced from the properties of the constituent halite crystals. A model for the elastoplastic behaviour of halite crystal has been deduced from experimental data available in the literature. The basic equations of the micro–macro model for the polycrystalline medium and the calculation method are then presented and the elastoplastic behaviour of rock salt is investigated by this method. The hardening effects obtained for the polycrystal are found to be very different from those obtained for FCC metal polycrystals. The differences are explained as a consequence of differences of families of glide systems in these crystals. Finally, the internal stresses in the polycrystal are studied in order to elucidate the origin of cracking and damage of the rock salt. 相似文献
9.
Application of 2‐(benzyliminomethyl)‐6‐methoxy‐4‐(4‐methoxyphenyl‐azo)phenol in construction of ion‐selective PVC membrane electrode for determination of copper (II) in mineral water sample 下载免费PDF全文
The potentiometric characteristics of a new Cu2+‐selective electrode based on 2‐(benzyliminomethyl)‐6‐methoxy‐4‐(4‐methoxyphenyl‐azo) phenol as an efficient ionophore has been evaluated. The effects of influential parameters on the potentiometric responses such as the amount of plasticizer, the amount of ionophore, pH of the sample solution, and the effect of coexisting ions on the electrode signal were subsequently investigated . The selectivity of the electrode was assessed by calculating the selectivity coefficients using the matched potential method. The optimum ratio of the amount of materials required for the preparation of the electrode was found to be 1.7: 32.1: 64.2: 2.0 corresponding to carboxylated PVC, dimethyl sebacate as solvent mediators, potassium tetrakis (p‐chlorophenyl) borate as the anion localizing agent, and ionophore, respectively. The electrode had a fast response (7s) as well as a satisfactory Nernstian slope (29.26±0.91 mV/decade) to Cu2+ over a wide concentration range of 2.0×10?6‐ 5.0×10?2 M with a low detection limit of 5.9×10?7 M. The developed sensor was successfully used for the potentiometric titration of Cu2+ ion with EDTA and subsequently, efficient determination of this metal ion in a mineral water sample was performed. 相似文献
10.
Dr. Pouya Partovi-Azar Dr. Chandra Shekar Sarap Prof. Dr. Maria Fyta 《Chemphyschem》2019,20(17):2166-2170
We report on the specific interaction of a small diamond-like molecule, known as diamondoid, with single amino-acids forming nano/bio molecular complexes. Using time-dependent density-functional theory calculations we have studied two different relative configurations of three prototypical amino acids, phenylalanine, tyrosine, and tryptophan, with the diamondoid. The optical and charge-transfer properties of these complexes exhibit amino acid and topology specific features which can be directly utilized for in the direction of novel biomolecule detection schemes. 相似文献