Equilibrium and kinetic studies for the adsorption of benzene and toluene by graphene nanosheets: a comparison with carbon nanotubes

In this study, graphene nanosheets (GNSs) were adopted as an adsorbent to investigate their characterizations and performance for adsorbing benzene and toluene in aqueous solutions. In order to determine the best fit model for each considered system, nonlinear regressions were used. Experimental data of adsorption were corroborated by the combined Langmuir–Freundlich (Sips) models for the isotherms and pseudo‐first‐order model for the kinetics. As a result, GNSs displayed high affinity to the aromatic hydrocarbons such as benzene and toluene. The high affinity was dominated by π–π interactions to the flat surface and the sieving effect of the powerful groove regions formed by wrinkles on GNS's surfaces. Hydrophobic properties and molecular sizes of benzene and toluene affected the adsorption of GNS. In addition, the favorable adsorption of toluene possibly was due to the increase in the molecular weight, decrease in the solubility, and the increase in the boiling point. A comparative study on the benzene and toluene adsorption revealed that favorable adsorption of GNSs compared with that of carbon nanotubes was consistent with the order of physical properties such as specific surface area and pore's volume. Copyright © 2016 John Wiley & Sons, Ltd.     

Graphene-Oxide-Based Fluoro- and Chromo-Genic Materials and Their Applications

Composite materials and their applications constitute a hot field of research nowadays due to the fact that they comprise a combination of the unique properties of each component of which they consist. Very often, they exhibit better performance and properties compared to their combined building blocks. Graphene oxide (GO), as the most widely used derivative of graphene, has attracted widespread attention because of its excellent properties. Abundant oxygen-containing functional groups on GO can provide various reactive sites for chemical modification or functionalization of GO, which in turn can be used to develop novel GO-based composites. This review outlines the most recent advances in the field of novel dyes and pigments encompassing GO as a key ingredient or as an important cofactor. The interactions of graphene with other materials/compounds are highlighted. The special structure and unique properties of GO have a great effect on the performance of fabricated hybrid dyes and pigments by enhancing the color performance of dyes, the anticorrosion properties of pigments, the viscosity and rheology of inks, etc., which further expands the applications of dyes and pigments in dyeing, optical elements, solar-thermal energy storage, sensing, coatings, and microelectronics devices. Finally, challenges in the current development as well as the future prospects of GO-based dyes and pigments are also discussed. This review provides a reference for the further exploration of novel dyes and pigments.     

Theoretical description of electron phonon Fock space for gapless and gapped nanowires

We study the effect of electron–phonon(e–ph) interaction on the elastic and inelastic electronic transport of a nanowire connected to two simple rigid leads within the tight-binding and harmonic approximations. The model is constructed using Green's function and multi-channel techniques, taking into account the local and nonlocal e–ph interactions. Then, we examine the model for the gapless(simple chain) and gapped(PA-like nanowire) systems. The results show that the tunneling conductance is improved by the e–ph interaction in both local and nonlocal regimes, while for the resonance conductance, the coherent part mainly decreases and the incoherent part increases. At the corresponding energies which depend on the phonon frequency, two dips in the elastic and two peaks in the inelastic conductance spectra appear. The reason is the absorption of the phonon by the electron in transition into inelastic channels.     

ZnO thin film characterization by X-ray reflectivity optimization using genetic algorithm and Fourier transformation

Zinc oxide (ZnO) thin film was fabricated by sol-gel spin coating method on glass substrate. X-ray reflectivity (XRR) and its optimization have been used for characterization and extracting physical parameters of the film. Genetic algorithm (GA) has been applied for this optimization process. The model independent information was needed to establish data analyzing process for X-ray reflectivity before optimization process. Independent information was exploited from Fourier transform of Fresnel reflectivity normalized X-ray reflectivity. This Fourier transformation (Auto Correlation Function) yields thickness of each coated layer on substrate. This information is a keynote for constructing optimization process. Specular X-ray reflectivity optimization yields structural parameters such as thickness, roughness of surface and interface and electron density profile of the film. Acceptable agreement exists between results obtained from Fourier transformation and X-ray reflectivity fitting.     

On the Position Representation of Pedram’s Higher Order GUP

In this paper we show that the position representation of the higher order generalized uncertainty principle (HGUP) is also well defined without approximation. We find the simpler form of this representation with a help of the signature of the discriminant of the cubic equation. Using this we discuss the HGUP derivative, HGUP exponential and HGUP trigonometric functions and HGUP-corrected Bohr atom model. Finally we discuss the D-dimensional HGUP algebra and compute the cosmological constant.

     

Synthesis,molecular modeling,TD-DFT,antimicrobial, and in vitro therapeutic activity of new spherical nano-sized sulfonamide imine ligands and their zinc (II) and copper (II) complexes

A series of nanometer-sized spherical sulfonamide imine ligands HL ¹ -HL ⁵ and their copper and zinc complexes were synthesized and fully characterized based on elemental analyses, spectroscopic (UV/vis, FT-IR, NMR, EPR, SEM) studies, molar conductance and thermal analyses. Furthermore, computational studies of HL ¹ -HL ⁵ were carried out by the DFT/B3LYP method. TD-DFT, HOMO and LUMO energy values, chemical hardness, electronegativity, electrophilic index, softness, and other parameters were calculated. Screening against several pathogenic microorganisms indicated that HL ¹ exhibited high activity against the tested Gram-negative bacteria relative to other analogues and the inhibition activity is greater than the standard Gentamicin. Analogously, HL ² exhibited high potent activity against the tested Gram-positive bacteria. Copper complexes exhibited a higher potent activity than zinc analogues. Noteworthy, inhibition activity of [Cu ( L ³ )(OAc)] complex is higher than that of the standard Ampicillin. [Cu ( L ² )(OAc)] complex displayed a similar activity of the standard bactericides and fungicides in use. The complexes showed appreciated values of MIC against bacterial strains: B. subtilis (MIC = 0.4 μg / mL), E. coli and S. pneumonia (MIC = 1.95 μg / mL) and P. aeruginosa (MIC = 7.81 μg / mL). in vitro cytotoxic activities study proved that [Cu ( L ³ )(OAc)] complex exhibited appreciable activity versus (HEPG-2); IC₅₀ = 4.8 μg/ml, while [Cu( L ² )(OAc)] complex showed a high activity against (MCF-7); IC₅₀ = 6.2 μg/ml. These results could be considered as new findings of promising antitumor candidates for experimental chemotherapy.     

An Exact Family of Einstein–Maxwell Wyman–Adler Solution in General Relativity

This paper presents a family of two-parametric interior solutions of Einstein–Maxwell field equations in general relativity for a static spherically symmetric distribution of a charged perfect fluid with particular choice of charge distribution and the metric component g ₀₀. This family gives us wide range of parameters, n and K, for which the solutions are regular and acceptable on physical grounds and hence suitable for modeling of charged compact star. The maximum allowable mass and corresponding radius, for this family of solutions with the particular form of charge distribution, is determined to be 2.48M _⊙ and 10.56 km respectively by assuming the stellar “surface” density equal to strange (quark) matter density at zero pressure. It is hoped that our investigation may be of some importance in connection with the study of internal structure of electrically charged strange (quark) star.     

Oscillation Criteria for Functional Nonlinear Dynamic Equations with $${\gamma}$$ -Laplacian,Damping and Nonlinearities Given by Riemann–Stieltjes Integrals

In this paper, we present oscillation criteria for the second-order nonlinear dynamic equation \({[a(t)\phi_{\gamma} (x^{\Delta}(t))]^{\Delta} + p(t)\phi_{\gamma}(x^{\Delta^{\sigma}}(t)) + q_{0}(t) \phi_{\gamma}(x(g_{0}(t)))+\sum_{i=1}^{2}\int_{a_{i}}^{b_{i}}q_{i}(t,s)\phi_{\alpha_{i}(s)}(x(g_{i}(t,s))) \Delta \zeta_{i}(s)=0}\) on a time scale \({\mathbb{T}}\) which is unbounded above. Our results generalize and improve some known results for oscillation of second-order nonlinear dynamic equation. Some examples are given to illustrate the main results.     

Transport equations of higher order discontinuities for quasilinear hyperbolic systems

The transport equations satisfying ordinary linear differential equations of first order which govern the behaviour of higher order discontinuities for quasilinear hyperbolic systems along the rays associated with a singular surface are derived. It is shown that the transport equations depend on the Gaussian curvature of wave front.     

Ultra-Sensitive Fluorimetric Method for the First Estimation of Vonoprazan in Real Human Plasma and Content Uniformity Test

Journal of Fluorescence - Vonoprazan (VON) has been approved recently via US-FDA in 2015 as the first in class of potassium competitive acid blocker group. VON is used for management of...