The influence of the surface roughness on dielectric function of two-dimensional electron gas: a Lindhard model approach

Low field response function calculations have been performed on a two-dimensional electron gas with well-defined electron-surface roughness scattering. The Lindhard model was employed to compute the response function. In particular, detailed investigations were made on the system searching for an interplay between surface roughness with well-defined correlation function, (characterizes by asperity height and correlation length) spatial confinement and the dielectric function. We analyze to what extent the normal behavior and functionality of dielectric function of two-dimensional devices are modified by random scattering events caused by the contribution from the surface roughness. Results of the current work indicate that contribution of the surface roughness on scattering and absorption process could not be considered as an underestimating effect. We find, however, that functionality of the dielectric function seems to be quite independent of the particular roughness features.     

Podophyllotoxin extraction from Linum usitatissimum plant and its anticancer activity against HT‐29, A‐549 and MDA‐MB‐231 cell lines with and without the presence of gold nanoparticles

In recent years, gold nanoparticles (Au‐NPs) have been taken into consideration in nanomedicine due to their excellent biocompatibility, chemical stability and promising optical properties. In this research, podophyllotoxin conjugated with gold nanoparticles (Au‐NPs‐POT) was synthesized and the conjugation of POT with Au‐NPs was confirmed using scanning electron microscopy, mass spectrometry and Fourier transform infrared spectroscopy. The anticancer effects of the product on preclinical models of lung, colon and breast cancers were investigated using MTT test. The analyses showed a direct dose–response relationship. It was found that higher concentrations of POT have more positive effects on the inhibition of cancer cell growth. At POT concentrations of 1, 2.5, 5, 7.5, 10, 15 and 20 ng ml^?1, approximately 50% of the growth of colorectal, lung and breast cancer cell lines was inhibited, while similar results were obtained in the presence of 1, 2, 3, 4 and 5 μg ml^?1 Au‐NPs‐POT. Au‐NPs‐POT exhibited the lowest cytotoxicity due to the presence of POT. The anticancer feature of Au‐NPs‐POT proved the potential to develop better anticancer therapeutics and to open new avenues for treatment of cancers.     

Synthesis of CuS nanoparticles loaded on activated carbon composite for ultrasound‐assisted adsorption removal of dye pollutants: Process optimization using CCD‐RSM,equilibrium and kinetic studies

In this study, the CuS nanoparticles loaded on activated carbon (CuS‐NPs‐AC) composite was synthesized and then, characterized by XRD and FE‐SEM analyses. The prepared composite was used as a potential adsorbent for the simultaneous ultrasound‐assisted removal of Indigo Carmine (IC) and Safranin‐O (SO). The CuS‐NPs‐AC dose (0.01‐0.03 g), sonication time (1‐5 min), initial SO concentration (5‐15 mg L^‐1) and initial IC concentration (5‐15 mg L^‐1) as expectable effective parameters were studied by central composite design (CCD) under response surface methodology (RSM) to obtain an useful knowledge about the effect of simultaneous interaction between IC and SO on their removal percentage. The optimum SO and IC removal percentages were determined to be 98.24 and 97.15% at pH = 6, 0.03 g of the CuS‐NPs‐AC, 3 min sonication time, 12 and 10 mg L^‐1 of IC and SO. The values of coefficient of determination (R²) for SO and IC were 0.9608 and 0.9796, respectively, indicating the favorable fitness of the experimental data to the second order polynomial regression model. The isotherm data were well correlated with Freundlich model. The maximum monolayer adsorption capacities of 87.5 and 69.90 mg g^‐1 at room temperature for IC and SO in the investigated binary system expressed the high efficiency of the novel adsorbent for water cleanup within a short time. The investigation of correlation between time and rate of adsorption revealed that IC and SO adsorption onto the CuS‐NPs‐AC followed pseudo‐second‐order and intra‐particle diffusion simultaneously.     

Topical propolis improves wound healing in patients with diabetic foot ulcer: a randomized controlled trial

In this randomized controlled trial, diabetic patients with foot ulcers (Wagner grades 1 and 2) were randomly assigned to conventional therapies for diabetic foot ulcer plus topical propolis ointment (5%; twice daily) or conventional therapies alone. The process of ulcer healing was observed during 4 weeks and compared between the two groups regarding the size, erythema, exudates, white blood cell (WBC) count and erythrocyte sedimentation rate (ESR). The process of ulcer size reduction during the four-week period of study was significantly different between the groups. However, this difference was not significant between the third and fourth weeks. There was no significant difference between two groups regarding erythema and exudate reduction as well as WBC count and ESR. Administration of topical propolis ointment in addition to the conventional treatments of diabetic foot ulcer could reduce the size of ulcers with Wagner grades 1 and 2.     

A one-pot synthesis of 5,5-disubstituted hydantoin derivatives using magnetic Fe3O4 nanoparticles as a reusable heterogeneous catalyst

A facile and rapid method for the one-pot synthesis of 5,5-disubstituted hydantoins in the presence of magnetic Fe₃O₄ nanoparticles has been developed. The multicomponent reactions of carbonyl compounds (aldehydes and ketones), potassium cyanide and ammonium carbonate were carried out under solvent-free conditions to obtain various hydantoin derivatives. The magnetic catalyst could be readily separated by an external magnet from the reaction mixture. This procedure has many advantages, such as the use of a reusable magnetic catalyst, high yields, short reaction times, simplicity and very easiness with implementing the methodology.     

Aggregation behavior and intermicellar interactions of cationic Gemini surfactants: Effects of alkyl chain,spacer lengths and temperature

The aggregation behavior of the cationic Gemini surfactants C_mH_2m+1N(CH₃)₂(CH₂)_S (CH₃)₂ N C_mH_2m+1,2Br^? with m = 12, 14 and s = 2, 4 were studied by performing surface tension, electrical conductivity, pulsed field gradient nuclear magnetic resonance (PFG-NMR), and cyclic voltammetry (CV) measurements over the temperature range 298 K to 323 K. The critical micelle concentration (CMC), surface excess (Г_max), mean molecular surface area (A_min), degree of counter ion dissociation (α), and the thermodynamic parameters of micellization were determined from the surface tension and conductance data. An enthalpy–entropy compensation effect was observed and all the plots of enthalpy–entropy compensation exhibit excellent linearity. The micellar self-diffusion coefficients (D_m) and intermicellar interaction parameters (k_d) were obtained from the PFG-NMR and CV measurements. These results are discussed in terms of the intermicellar interactions, the effects of the chain and spacer lengths on the micellar surface charge density, and the phase transition between spherical and rod geometries. The intermicellar interaction parameters were found to decrease slightly with increasing temperature for 14–4–14, which suggests that the micellar surface charge density decreases with increasing temperature. The mean values of the hydrodynamic radius, R_h, and the aggregation number, N_agg, of the Gemini surfactants’ m–4–m micelles were calculated from the micellar self-diffusion coefficient. Moreover, the N_agg values were calculated theoretically. The experimental values of N_agg increase with increases in the chain length and are in good agreement with both previous results and our theoretical results.     

Pre‐concentration of trace amount of bisphenol A in water samples by palm leaf ash and determination with high‐performance liquid chromatography

Palm leaf ash was characterized and used as low‐cost adsorbent for solid‐phase extraction and preconcentration of bisphenol A (BPA) in real water samples. Analysis of BPA was carried out using HPLC involving Eurospher 100–5‐C₁₈ (25 cm × 4.5 mm, particle size 5 μm) column and water–acetonitrile (40:60, v/v) as mobile phase. The adsorption was achieved quantitatively at a pH of 6 with elution by 3 mL acetonitrile. The limits of detection and enrichment factor were 0.02 μg L^?1 and 333, respectively. Under optimum conditions the relative standard deviation (RSD) was 2% (n = 10). Comparison of qualification criteria of presented preconcentration procedure with other research indicated that palm leaf ash adsorbent was better than many of the adsorbents in terms of cost and reusability. Also, the limit of detection, precision and enrichment factor were comparable and even better than the previously reported methods. Finally, the efficiency of method was computed by determination of trace amounts of BPA in sea, river, mineral and tap waters with recoveries of 93.3–105.5% and RSDs of 0.61–3.12%.. Briefly, the developed solid‐phase extraction and Preparative layer chromatography (PLC) methods may be used for bisphenol A monitoring in any environmental water sample. Copyright © 2016 John Wiley & Sons, Ltd.     

Non-covalent intermolecular interactions of colloidal nematic liquid crystals doped with graphene oxide

Graphene oxide (GO) was doped to eutectic uniaxial nematic liquid crystals (NLCs) (E_5CN7) with different percentages to improve the physiochemical properties of NLCs effectively. GO shifts the N-I phase transition temperature to higher values. It has been observed that increasing GO concentration up to 0.75% increases the N-I phase transition temperature substantially while further increase of GO concentration results in an inverse trend. The GO/E_5CN7 non-covalent interactions change the N-I phase transition. The contribution of several terms such as anchoring and polarisation effects on N-I phase transition was quantified as well. The results suggest that the size is an important contributor to GO and liquid crystal interaction. The results show that E_5CN7@GO composites may act as promising candidates to enhance the efficiency of room temperature devices.     

Microwave-Promoted Facile and Rapid Synthesis Procedure for the Efficient Synthesis of 5,5-Disubstituted Hydantoins

A fast, general, environmentally friendly, and facile method for preparation of 5, 5-disubstituted hydantoins from the reaction between ketone (or aldehyde) derivatives with KCN and ammonium carbonate under microwave irradiation is presented. The microwaves remarkably accelerated this reaction, the reaction times decreased dramatically, the reaction conditions were milder, and the yields were also greater. Also a comparative study of microwave versus classical conditions has been done. All the products were characterized by infrared, NMR, and CHN analysis, and their melting points are identical to those of the known compounds reported in the literature. This method might be useful in the future for the preparation of similar derivatives.

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