Gold Nanoparticles Supported on the Periodic Mesoporous Organosilicas as Efficient and Reusable Catalyst for Room Temperature Aerobic Oxidation of Alcohols

Gold nanoparticles supported on the channels of a bifunctional periodic mesoporous organosilica, were found to be a highly efficient catalyst system for the aerobic oxidation of various types of alcohols into their corresponding aldehydes and ketones at room temperature. The catalyst showed no significant loss of efficiency for the aerobic oxidation of benzyl alcohol to give benzaldehyde after 7 reaction cycles.     

Modeling of salient-pole brake with hollow nonmagnetic rotor

Analytical expressions for the electromagnetic torque of a salient-pole brake with a hollow nonmagnetic rotor are obtained. Mechanical characteristics obtained based on the FEM and analytical dependences are compared. The effects of design factors on the torque and the mechanical characteristics are investigated.     

Optimal placement of PMUs to maintain network observability using a modified BPSO algorithm

This paper presents a novel approach to optimal placement of Phasor Measurement Units (PMUs) for state estimation. At first, an optimal measurement set is determined to achieve full network observability during normal conditions, i.e. no PMU failure or transmission line outage. Then, in order to consider contingency conditions, the derived scheme in normal conditions is modified to maintain network observability after any PMU loss or a single transmission line outage. Observability analysis is carried out using topological observability rules. A new rule is added that can decrease the number of required PMUs for complete system observability. A modified Binary Particle Swarm Optimization (BPSO) algorithm is used as an optimization tool to obtain the minimal number of PMUs and their corresponding locations while satisfying associated constraint. Numerical results on different IEEE test systems are presented to demonstrate the effectiveness of the proposed approach.     

Optical and Electrical Properties of Colloidal Quantum Dots in Electrolytic Environments: Using Biomolecular Links in Chemically-Directed Assembly of Quantum Dot Networks

The threshold of the absorption spectra of colloidal cadmium sulfide (CdS) quantum dots in electrolytic solutions is shown to shift as the concentration of the electrolyte is varied. The shift in the absorption threshold as a function of the electrolytic concentration is given by electrolytic screening of the field caused by the intrinsic spontaneous polarization of these würtzite quantum dots. These electrolyte-dependent absorption properties are compared with Fermi-level tuning in carbon nanotubes in electrolytic environments.Moreover, concepts for integrating such colloidal quantum dots in high density networks with biomolecular links are discussed. Such biomolecular links are used to facilitate the chemically-directed assembly of quantum dots networks with densities approximating 10¹⁷ cm⁻³.     

Engineering of a Red Fluorogenic Protein/Merocyanine Complex for Live-Cell Imaging

A reengineered human cellular retinol binding protein II (hCRBPII), a 15-kDa protein belonging to the intracellular lipid binding protein (iLBP) family, generates a highly fluorescent red pigment through the covalent linkage of a merocyanine aldehyde to an active site lysine residue. The complex exhibits “turn-on” fluorescence, due to a weakly fluorescent aldehyde that “lights up” with subsequent formation of a strongly fluorescent merocyanine dye within the binding pocket of the protein. Cellular penetration of merocyanine is rapid, and fluorophore maturation is nearly instantaneous. The hCRBPII/merocyanine complex displays high quantum yield, low cytotoxicity, specificity in labeling organelles, and compatibility in both cancer cell lines and yeast cells. The hCRBPII/merocyanine tag is brighter than most common red fluorescent proteins.     

Photodegradation of methylene blue with a titanium dioxide/polyacrylamide photocatalyst under sunlight

Hydrogels containing TiO₂ nanoparticles (NPs) have photocatalytic properties and degrade pollutants under light. In this study, a polyacrylamide (PAAm) hydrogel was synthesized with TiO₂ P25 NPs as the initiator, acrylamide as a monomer, and N,N′‐methylene bisacrylamide as a crosslinker in aqueous media under sunlight. Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy were applied to characterize the TiO₂/PAAm hydrogel. The effects of different synthetic conditions, such as the initiator concentration, crosslinker, and dilution, on swelling were investigated. The maximum swelling of the TiO₂/PAAm hydrogel was 45 g/g in the hydrogel synthesized with optimum conditions by 0.2% TiO₂. The photocatalytic degradability of the hydrogel was investigated with methylene blue (MB) as the pollutant target. Also, the effects of the pH and MB concentration were studied. Under optimum conditions, 95.00% of the MB was degraded by the TiO₂/PAAm photocatalyst after 5 h of irradiation under sunlight. The comparison of the results with those of the TiO₂ P25 powder showed that the TiO₂ NPs had better activity than the hydrogel, but unlike the hydrogel, the activity of these NPs decreased in each recycling time because of the aggregation of NPs. Finally, the hydrogel was recycled seven times without a considerable reduction in the degradation efficiency. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43386.     

Thermolysis Synthesis of Pure Phase Nano-Sized Cobalt(II) Oxide from Novel Cobalt(II)-Pyrazole Discrete Nano Coordination Compound

Nano-structures of a new discrete coordination compound of divalent cobalt with the pyrazol (pzH) containing the terminal isothiocyanate anions, [Co(pzH)₂(NCS)₂] (1), with discrete molecular architecture in solid state was synthesized by a sonochemical method. The new nanostructure was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, IR, and elemental analysis. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The discrete molecules interact with each other through labile interactions creating a 3D supramolecular framework. The CoO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant.     

Improving rheological properties of covalently MWCNT/epoxy nanocomposites via surface re-modification

This article describes the application of the chemical surface re-modification of carboxylated multi-walled carbon nanotubes (MWCNTs) through in-situ esterification of oligomeric unsaturated aliphatic hydroxyl terminated polyesters. The Fourier transform infrared spectroscopy and the thermogravimetric analysis proved covalent treatment of MWCNTs. Consequently, the acid–base titration method was employed to determine the population of the re-modified sites within the polyester chains. The dispersion state of the re-modified MWCNTs was investigated by the transmission electron microscopy relevant to the cured nanocomposite sample along with the Ultraviolet–Visible spectroscopy while using various solvents. The degree of dispersion was correlated to the Hansen solubility parameters. In summary, our study shows an appropriate dispersion of the re-modified MWCNTs into the solvents with a high dispersive fashion. In addition, the rheological properties of the re-modified MWCNTs/epoxy resin having various nanoinclusions were considerably studied and discussed. Also, an improved rheological response was observed in the case of the re-modified MWCNT nanocomposite samples.     

Highly Efficient Adsorption of Anionic Dyes from Aqueous Solutions Using Sawdust Modified by Cationic Surfactant of Cetyltrimethylammonium Bromide

In the present study, the adsorption behavior of Congo Red (CR) dye from aqueous systems onto sawdust modified by cetyltrimethylammonium bromide, CH₃(CH₂)₁₅N(CH₃)₃Br (CTAB) was attempted. Adsorption experiments were carried out using both batch and column modes under various operating conditions. The effects of some important parameters such as solution pH, adsorbent dosage, initial dye concentration and contact time were investigated. Treatment of the equilibrium data obtained in batch experiments was carried out using Langmuir and Freundlich isotherm equations. Based on the isotherm analysis, it was found that the adsorption of CR dye onto SD fits well to the Langmuir model and the adsorption pattern on CTAB modified sawdust (CTAB/SD) followed the Freundlich isotherm which is indicative of heterogeneity of the adsorption sites on the surfactant-modified sawdust. The maximum adsorption capacity of SD and CTAB/SD were found to be 5.2 and 9.1?mg?g^?1, respectively, according to the Langmuir model. However, much higher differences in sorption capacities were observed for CTAB/SD and SD in the column system (66.73?mg?g^?1). In order to find out the possibility of the exhausted column for frequent use, a regeneration study was also carried out. It was found that the dye uploaded column can be easily regenerated with a high performance using ethanol as the washing solution.     

Synthesis, Structural Investigation and DFT Calculations of Cadmium (II) Fluorine-Substituted β-Diketonate: A Precursor to Producing Pure Phase Nano-Sized Cadmium (II) Oxide

A novel aza-aromatic base adduct of a cadmium(II) fluorine-substituted β-diketonate, [Cd(dmp)(ttfa)₂]_n(1), (“dmp” is an abbreviation for 2,9-dimethyl-1,10-phenanthroline and “ttfa” is an abbreviation for thenoyltrifluoroacetonate) was synthesised and characterised by elemental analysis and IR, ¹H NMR and ¹³C NMR spectroscopy and studied by thermal as well as X-ray crystallography. The single-crystal structure of this complex shows that the coordination number of the Cd²⁺ ion is six with two N-donor atoms from the dmp ligand and four O-donors from ttfa. Self-assembly of this complex was mediated by CH···F–C and π–π stacking interactions. The supramolecular features of these complexes are controlled by weak directional intermolecular interactions. The structural energy of the title complex was determined by density functional theory calculations. The calculated HOMO–LUMO gap is 0.131 a.u. (3.474?eV). The CdO nano-particles were obtained by thermolysis of 1 at 180?°C with oleic acid as the surfactant. Scanning electron microscopy showed that the size of the CdO particles is ~35?nm.