A computational investigation of the electronic properties of Octahedral Al n N n and Al n P n cages (n = 12, 16, 28, 36, and 48)

Density functionla theory (DFT) calculations are performed to characterize geometric and electronic features of the octahedral Al _n N _n and Al _n P _n cages (n = 12, 16, 28, 32, and 48). Toward this aim, ¹⁵N, ²⁷Al, and ³¹P chemical shielding (CS) tensors as well as natural charge analyses are calculated for the optimized structures. CS parameters detect three distinct electronic environments for atoms within the Al _n N _n and Al _n P _n cages. The chemical shifts of N2 sites belonging to a hexagon and surrounded by three hexagons and a square obtained are different from those of N3 sites belonging to a hexagon that is surrounded only by hexagons—due to different curvatures exerted at the sites with different local structures. In addition, there is an increasing tendency in the Δσ values of the three local structures, Δσ (N1) > Δσ (N2) > Δσ (N3), N1 sites belonging to four-membered rings. The chemical shieldings of those Al and P sites belonging to a hexagon that is surrounded only by hexagons in the cages (360.7–366.7 and 496.5–514.7 ppm) are close to those previously reported for AlP nanotubes. Three distinct electrostatic environments around the N, Al, and P nuclei are also confirmed by the calculated natural charges. It should be noted that the positively charged Al atoms on the cages turn out to be the available sites for adsorption of H2 molecules.     

Low Temperature Preparation of 3D Solid and Hollow ZnS Nanosphere Self-Assembled from Nanoparticles by Varying Sulfur Source

In this work, we report a facile hydrothermal method for the preparation of three dimensional hollow ZnS nanostructures, using Zinc bis(salicyle aldehitato), Zn(Sal)₂, thioacetamide (TAA) and thioglycolic acid (TGA) as Zn²⁺, sulfur source and capping agent, respectively. The ZnS solid and hollow sphere was produced from the self-assembly of nanoparticles with diameters of 11 ± 2 nm with TGA and TGA, TAA, respectively. Furthermore, with changing zinc precursor from Zn(Sal)₂ to zinc acetate [Zn(OAC)₂], ZnS nanorods were obtained. The products were characterized by XRD, SEM, TEM, selected area electron diffraction, and FT-IR spectra. The influence of surfactant (Polyethylene glycol) on the morphology of the products was also investigated. Possible formation mechanism and optical properties of these architectures were also reported.     

Lanthanum-selective sensors based on 3-amino-2-mercapto-3H-quinazolin-4-one in PVC matrix

A new solvent polymeric membrane (PME) and coated graphite (CGE) electrodes based on 3-amino-2-mercapto-3H-quinazolin-4-one as a suitable carrier for La(III) ion are described. The sensors exhibited a Nernstian response for La(III) ion over a wide concentration range (3.0 × 10^?7 to 1.0 × 10^?1 M for PME and 1.0 × 10^?7 to 1.0 × 10^?1 M for CGE) with a slope of 20.1 ± 0.3 (PME) and 23.4 ± 0.4 (CGE) mV decade^?1. The lower detection limits by PME and CGE were 2.0 × 10^?7 and 7.1 × 10^?8 M, respectively. The potentiometric response of the proposed electrodes was independent of the pH of the test solution in the pH range 3.0–9.0 with a fast response time (<10 s). The applications of prepared sensors were demonstrated in the determination of lanthanum ions in spiked water sample and also utilized for indirect determination of fluoride content of two mouth wash preparation samples.     

Convenient Synthesis of New Boric Acid Catalyzed 1,2,4‐Triazolopyridinone Derivatives and an Investigation of their Optical Properties

Syntheses of fused heterobicyclic systems containing 1,2,4‐triazolopyridinone moieties were accomplished by heterocyclization of 1,6‐diamino‐2‐oxo‐4‐phenyl‐1,2‐dihydropyridine‐3,5‐dicarbonitriles and ninhydrin in ethanol and in the presence of boric acid as a catalyst in 30 min at room temperature. All compounds have been screened for their photophysical properties. Results showed that all compounds exhibit near infrared emissions at 876 nm.     

Solvent‐Free Chemoselective Synthesis of 1,1‐Diacetates Catalyzed by Cu(NO3)2 · 3H2O

1,1‐Diacetates have been synthesized by the reaction of a variety of aldehydes with acetic anhydride in the presence of cupric nitrate as catalyst under solvent‐free conditions. Ketones were not converted to the corresponding diacetates under these conditions.     

Synthesis of Functionalized Pyrroles by Reaction of 3,4‐Diacetylhexane‐2,5‐dione with Primary Amines in Water

3,4‐Diacetylhexane‐2,5‐dione (tetra‐acetylethane) undergoes a complex reaction with primary amines in boiling water to produce N‐alkyl‐3‐acetyl‐2,5‐dimethylpyrroles, together with small quantities of N‐alkyl‐3,4‐diacetyl‐2,5‐dimethylpyrroles and 2,5‐dimethyl‐1H‐pyrrol‐3‐yl‐vinyl‐acetamides. When the reaction was carried out in methanol at room temperature, the yields of the latter products increased.     

Characterization of Chitosan/Alginate Self-Assembled Nanoparticles as a Protein Carrier

The aim of this study was to evaluate the effect of the polymeric ratios on the characteristics of chitosan/alginate (ch/alg) self-assembled nanoparticles and their potential as protein delivery vehicle. The nanoparticles were prepared using proper mixing of polymers in presence or absence of bovine serum albumin (BSA) as a protein model. Three formulations of nanoparticles comprising ch/alg ratios of 2:1, 1:1, and 1:2 were prepared. Size, shape and zeta potential of the formulations were studied by scanning electron microscopy (SEM) and nanosizer instruments. FTIR, and differential scanning calorimetery (DSC) studies were performed to investigate polymer-polymer or polymer-protein interactions. Release profiles and entrapment efficiencies of the nanoparticles were determined by calorimetric technique using appropriate techniques. Entrapment efficiency was 70% for ch/alg ratio of 1:1, 65% for 1:2, and 60% for 2:1. The z-average size of the nanoparticles were 403, 205, and 318 nm for ch/alg ratios of 2:1, 1:1, and 1:2, respectively. Average zeta potentials were ?47, +15, ?25 mV for 2:1, 1:1, and 1:2 as well. Considering the favorable features required for protein delivery systems, ch/alg (1:1) due to its smallest size, highest loading, and most homogenous shape was regarded as the best ratio.     

Ligandless-ultrasound-assisted emulsification microextraction followed by inductively coupled plasma-optical emission spectrometry for simultaneous determination of heavy metals in water samples

In this study, a simple and efficient method of ligandless-ultrasound-assisted emulsification microextraction (LL-USAEME) followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) has been developed for simultaneous extraction, preconcentration and determination of manganese, cadmium, cobalt and nickel in water samples. In the proposed approach, tetrachloroethylene was selected as extraction solvent. The effect of important experimental factors such as volume of extraction solvent, pH, sonication time, salt concentration, and temperature was investigated by using a fractional factorial design (2^5?1) to identify important factors and their interactions. In the next step, a Box-Behnken design (BBD) was applied for optimisation of significant factors. The obtained optimal conditions were: 30?µL for extraction solvent, 12 for pH, 5?min for sonication time, and 5% w/v for salt concentration. The limits of detections (LODs) for Cd(II), Co(II), Mn(II) and Ni(II) were 0.20, 0.13, 0.21 and 0.28?µg?L^?1, respectively. Relative standard deviations (RSD, C?=?200.0?µg?L^?1, n?=?9) were between 3.4–7.5% and the calibration graphs were linear in the range of 0.25 to 1000.0?µg?L^?1 for Mn, 0.5–1000.0?µg?L^?1 for Co and Ni and 1.0–250.0?µg?L^?1 for Cd. The determination coefficients (R ²) of the calibration curves for the analytes were in the range of 0.993 to 0.999. The proposed method was validated by using two certified reference materials, and also the method was applied successfully for the determination of heavy metals in different real water samples.     

Magnetic solid-phase extraction of warfarin and gemfibrozil in biological samples using polydopamine-coated magnetic nanoparticles via core-shell nanostructure

Herein, polydopamine-coated Fe₃O₄ spheres were synthesized using a very simple, easy, cost-effective, efficient, and fast method. First, magnetic nanoparticles (Fe₃O₄) were synthesized and were followed by accommodating polydopamine on the surface of the prepared Fe₃O₄. The prepared polydopamine-coated Fe₃O₄ spheres were utilized as a sorbent in magnetic solid phase extraction of gemfibrozil and warfarin (as the model analytes). The extracted model analytes were desorbed by a suitable organic solvent and were analyzed by high-performance liquid chromatography. Under optimized condition, the linearity of the method was in the range of 0.1–200.0 μg/L for the selected analytes in water. The limits of detection were calculated to be in the range of 0.026–0.055 μg/L for warfarin and gemfibrozil, respectively. The limits of quantification were calculated to be in the range of 0.089–0.185 μg/L. The inter-day and intra-day relative standard deviations were determined to be in the range of 1.4%–3.3% in three concentrations in order to calculate the method precision. Furthermore, the enrichment factors were found to be 78 and 81 for warfarin and gemfibrozil, respectively. Moreover, the calculated absolute recoveries were between 78% and 81%. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.     

Microstructure of nickel nanoparticles embedded in carbon films: case study on annealing effect by micromorphology analysis

The presented study is aimed at analyzing the surface texture of amorphous hydrogenated carbon layers containing nickel nanoparticles (Ni‐NPs@a‐C:H) within their structure, which were deposited by Radio Frequency (RF) sputtering and RF‐Plasma Enhanced Chemical Vapor Deposition (RF‐PECVD) methods on glass substrates. Prepared films were then used as research material following their annealing at two different temperatures of 250 °C and 350 °C in an inert argon atmosphere. Series of height samples were taken with the help of atomic force microscopy (AFM) operating in a non‐contact mode and examined in order to determine their fractal characteristics. Raw AFM data were first plane‐fitted to remove the surface bow exhibiting the so‐called residual surface, and then numerically processed to calculate the Areal Autocorrelation Function (AACF), which was later used to compute the Structure Function (SF). The log–log plots of the latter served for calculation of fractal properties of surfaces under investigation, including fractal dimension D, and pseudo‐topothesy K. The analysis of 3‐D surface texture helps to understand their essential characteristics and their implications as well as graphical models and their implementation in computer simulation. Copyright © 2016 John Wiley & Sons, Ltd.