Coumarin-1,2,3-triazole hybrid derivatives: Green synthesis and DFT calculations

A series of new 1,2,3-triazole-coumarin hybrid system are synthesized from the click reaction between 3-azido coumarin and different aromatic terminal alkyne derivatives in a green manner. All compounds are characterized by IR, NMR and UV–VIS spectroscopy. The experimental observations are further supported by DFT computational studies to investigate the effect of substituents at para position in these compounds.     

Transverse discrete breathers in unstrained graphene

The European Physical Journal B - In this paper large resistor-capacitor (RC) networks that consist of randomly distributed conductive and capacitive elements which are much larger than those...     

Ethnomedicinal plant-extract-assisted green synthesis of iron nanoparticles using Allium saralicum extract,and their antioxidant,cytotoxicity, antibacterial,antifungal and cutaneous wound-healing activities

The aim of the experiment was the evaluation of antioxidant, cytotoxicity, antibacterial, antifungal and cutaneous wound-healing activities of green synthesized iron nanoparticles using Allium saralicum R.M. Fritsch leaves (FeNPs@AS). These nanoparticles were spherical with a size range of 40–45 nm, and were characterized using various analysis techniques including ultraviolet–visible spectroscopy to determine the presence of FeNPs@AS in the solution. We studied functional groups of A. saralicum extract in the reduction and capping process of FeNPs@AS by Fourier transform-infrared spectroscopy; crystallinity and FCC planes by X-ray diffraction pattern; and surface morphology, shapes and size of FeNPs@AS by scanning electron microscopy and transmission electron microscopy. Agar diffusion tests were done to determine the antibacterial and antifungal characteristics. FeNPs@AS prevented the growth of all bacteria and removed them at 2–8 mg/ml concentrations (P ≤ 0.01). In the case of antifungal potentials of FeNPs@AS, they inhibited the growth of all fungi and destroyed them at 2–4 mg/ml concentrations (P ≤ 0.01). The 2,2-diphenyl-1-picrylhydrazyl test revealed similar antioxidant potentials for FeNPs@AS and butylated hydroxytoluene. The synthesized FeNPs@AS had great cell viability dose-dependently and indicated this method was non-toxic. For the in vivo experiment, after creating the cutaneous wound, the rats were randomly divided into six groups: treatment with 0.2% FeNPs@AS ointment; treatment with 0.2% A. saralicum ointment; treatment with 0.2% FeCl₃·6H₂O ointment; treatment with 3% tetracycline ointment; treatment with Eucerin basal ointment; and untreated control. These groups were treated for 10 days. Use of FeNPs@AS ointment in the treatment groups significantly decreased (P ≤ 0.01) the wound area, total cells, neutrophils and lymphocytes, and significantly raised (P ≤ 0.01) the wound contracture, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte and fibrocytes/fibroblast rate compared with other groups. These results show that the inclusion of A. saralicum extracts improves the therapeutical properties of FeNPs, which led to a significant enhancement in the antioxidant, non-cytotoxicity, antibacterial, antifungal and cutaneous wound-healing activities of the nanoparticles.     

Surface characterizations of membranes and electrospun chitosan derivatives by optical speckle analysis

In this paper, we show that laser speckle pattern provides useful information toward revealing discrimination between nanofibers and membranes. Chitosan materials particularly organosoluble chitosan derivatives have a number of applications. The surface characteristics of these materials are very critical for specific applications. The analysis of laser speckles, both numerical and graphical, includes information about the surface structure. The development of digital electronics brought the ease of image processing and has opened new perspectives for a spectrum of laser speckle analysis (LASCA) applications. Our results show reasonable differences between the LASCA parameters of nanofibers and membranes. The methodology may be considered as a quantitative assessment tool for similar samples.     

MnO<Subscript>2</Subscript>/3MgO Nanocomposite for Preconcentration and Determination of Trace Copper and Lead in Food and Water by Flame Atomic Absorption Spectrometry

The presented study investigates the application of MnO₂/3MgO nanocomposite, as a new sorbent for solid phase extraction and determination of trace amounts of Pb²⁺ and Cu²⁺ from various samples using flame atomic absorption spectrometry. After extraction, the analytes were desorbed using 0.01 M ethylenediaminetetraacetic acid. The effects of various parameters were studied and optimized. Under optimized experimental conditions the linear dynamic ranges for Cu²⁺ and Pb²⁺ were 10?900 and 30?900 μg/L, respectively, with a preconcentration factor of 20. The detection limits of Cu²⁺ and Pb²⁺ were 4 and 11 μg/L, respectively, and relative standard deviations for eight determinations of 100 μg/L were 3.6 and 3.8% for Cu²⁺ and Pb²⁺, respectively. The method was successfully applied for determination of copper and lead in mushrooms, rice, tap water and refinery wastewater with good spike recoveries ranging between 95?106%.     

Pyrrole adsorption on aluminum nitride nanotubes on DFT data

The adsorption behavior of pyrrole molecule with external surface of (5.0) on zigzag aluminum nitride nanotube (AlNNT) was studied using density functional theory calculations. It was found that the adsorption energy (E_ad) of pyrrole on the surface of pristine nanotubes is about–11.99 kcal/mol. However, when nanotubes have been doped with P atom, the adsorption energy of pyrrole was increased. Calculation showed that for the phosphorus-doped nanotube the adsorption energy range is about–9.04 to?12.80 kcal/mol. AlNNT is a suitable adsorbent for pyrrole, so it can be used in adsorption and separation processes involving pyrrole. The doped AlNNT can potentially be used for pyrrole sensors for detection in environmental systems.     

Variational approaches to impulsive elastic beam equations of Kirchhoff type

In this paper, we study the existence of multiple solutions for impulsive fourth-order differential equations of Kirchhoff type. Using a variational method and some critical points theorems, we obtain some new criteria for guaranteeing that impulsive fourth-order differential equations of Kirchhoff type have three and infinitely many solutions. Some recent results are extended and improved. Some examples are presented to demonstrate the applications of our main results.     

Asymmetric synthesis of chiral oxindoles using isatin as starting material

Asymmetric synthesis plays an important role in the synthesis of therapeutics and natural products. Asymmetric oxindoles with a stereogenic quaternary carbon center are extensively present in various natural products and biologically active compounds. Several methods such as employing chiral auxiliaries or chiral catalysts were developed for asymmetric synthesis of spirooxindoles or 3,3-disubtituted oxindoles. In this review, we make a detailed overview of the latest developments in the use of isatin as starting material for the asymmetric synthesis of spirooxindoles and 3,3-disubstituted oxindoles during the period from 2015 to 2017.     

ZnO-nanoparticles as an efficient catalyst for the synthesis of tetrasubstituted cyclopentadienones using sulfonoketenimides and enaminoesters

A convenient and efficient approach to the synthesis of substituted cyclopentadienes is reported based on the reaction of sulfonoketenimides and enaminoesters in good yield. In these reactions, sulfonoketenimides is produced from the reaction of terminal alkynes and sulfonyl azides in the presence of copper iodide and enaminoesters is prepared via the reaction of dialkyl acetylenedicarboxylates and primary amines in the presence of ZnO-nanoparticles.     

Fabrication of the polyethersulfone/functionalized mesoporous carbon nanocomposite nanofiltration membrane for dyes and heavy metal ions removal: Experimental and quantum mechanical simulation method

The presence of industrial pollutants, especially salts, heavy metals ions, and dyes in water and wastewater is considered a serious environmental issue. To eliminate these pollutants, a high-performing nanofiltration (NF) membrane was prepared by blending the functionalized mesoporous carbon CMK-5 (F-CMK-5) nanofiller. This membrane was synthesized by introducing the active groups of sulfonyl and amide to the surface of mesoporous carbon CMK-5 through covalent functionalization. Characterizations were conducted to study the membranes' physical properties and separation performance in terms of antifouling properties and rejection of salts, heavy metal ions, and dyes. The interactions between the active sites of the nanocomposite membrane and the studied solutes, including dyes and heavy metal ions in aqueous solutions, were studied by the density functional based tight binding method and structural optimization was carried out. Insertion of the F-CMK-5 nanofiller was eventuated in a remarkable increase in surface hydrophilicity, pure water flux, and antifouling properties. For all membranes, the lowest and the highest salt rejection was obtained for NaCl and Na₂SO₄, respectively, exhibiting the characteristics of NF membranes. Moreover, M_0.3 with 0.3 wt% nanofiller showed the highest rejection for heavy metal ions (Fe²⁺ = 99.9%, Zn²⁺ = 99.9%, Cu²⁺ = 99.7%, and Pb²⁺ = 99.2%) and dyes (RB5 = 99.21, DR16 = 98.87, and MB = 98.12%), as well as high separation performance for filtration of multipollutant solutions. The reusability and 144 h uninterrupted filtration experiments for M_0.3 confirmed the stability of the membrane. The findings suggest that the PES/F-CMK-5 nanocomposite NF membrane is a promising candidate for water and wastewater treatment.