Cobalt(III) Complex [CoL3] Derived from an Asymmetric Bidentate Schiff Base Ligand L (L=(5‐Bromo‐2‐hydroxybenzyl‐2‐furylmethyl)‐imine): Synthesis,Characterization and Crystal Structure

Cobalt(III) complex [CoL₃], where L=(5‐bromo‐2‐hydroxybenzyl‐2‐furylmethyl)imine, has been synthesized by reacting cobalt(II) nitrate with L. The complex has been characterized by elemental analysis and FT‐IR spectroscopy. The crystal structure of [CoL₃] was determined by X‐ray crystallography from single crystal data. It crystallizes in the triclinic space group$ P {\bar 1} $ with unit cell parameters:a=9.6644(10) Å,b=11.5657(11) Å,c=16.5809(17) Å,α=102.833(4)°,β=102.999(3)°,γ=105.480(3)°,V=1659.9(3) ųandZ=2. Thermal decomposition of [CoL₃] was studied by thermogravimetry in order to evaluate its thermal stability and thermal decomposition pathways.     

The energy level shift of one-electron atom in Anti-(de Sitter) space time

In the present study we consider the Hamiltonian of the Dirac equation in curved space in fermi normal coordinates to first order in the Riemann tensor, including the corrections to the electromagnetic field. Then the energy level shifts by the local curvature for both relativistic and nonrelativistic levels in (Anti-)de Sitter space-time are calculated.     

Enzyme Free Electrochemiluminescence Sensor of Histamine Based on Graphite-carbon Nitride Nanosheets

The determination of histamine as one of the most important seafood poisoning compounds is essential nowadays. This paper reports a simple novel ECL sensor with g−C₃N₄ nanosheets (NSs) as an effective signal probe for the measurement of histamine without using any enzymatic reactions or complicated modifications. The ECL response of the sensor was linearly proportional to the concentration of histamine ranging from 1.0×10⁻⁷ to 7.5×10⁻⁴ mol/L, with a detection limit of 4.30×10⁻⁸ mol/L (R²=0.98401). The relative standard deviation (RSD) in repeatability and reproducibility tests were calculated to be 4.7 % and 3.6 % respectively. The presented sensor was successfully applied to the determination of histamine in canned tuna fish samples where it gave recoveries that ranged from 99.72 % to 101.96 % indicating that the method presented here is sensitive with high precision and is expected to have significant potential applications in clinical and the freshness quality of seafood.     

A Green Approach to the Bio-based Synthesis of Selenium Nanoparticles from Mining Waste

Journal of Cluster Science - This study deals with producing selenium nanoparticles (SeNPs) by an economical and reliable process using a mining waste that contains significant amounts of selenium...     

Accommodation in the formal world of mathematical thinking

ABSTRACT

In this study, we examined a mathematician and one of his students’ teaching journals and thought processes concurrently as the class was moving towards the proof of the Fundamental Theorem of Galois Theory. We employed Tall's framework of three worlds of mathematical thinking as well as Piaget's notion of accommodation to theoretically study the narratives. This paper reveals the pedagogical challenges of proving an elegant theory as the events unfolded. Although the mathematician was conscious of the students’ abilities as he carefully made the path accessible, the disparity between the mind of the mathematician and the student became apparent.     

Synthesis, characterization and fluorimetric studies of novel photoactive poly(amide-imide) from anthracene 9-carboxaldehyde and 4,4′-diaminodiphenyl ether by microwave irradiation

Trimellitic anhydride acid chloride (2) was obtained by the reaction of trimellitic anhydride (1) and excess amount of thionyl chloride. The acid chloride was reacted with 4,4′-diaminodiphenyl ether (3), and produced the monomer 4. Anthracene-9-carboxaldehyde (5) was reacted with sulfuryl chloride to produce anthracene-9-carboxylic acid chloride (6) in a quantitative yield. Through the reaction of 6 and 2,4,6-triamino-1,3,5-triazine (7), the monomer 8 was produced in high yield. Two monomers were characterized by ¹H NMR and FT-IR spectroscopy, and then were used in the polymerization reaction. A new facile and rapid polycondensation reaction of the two monomers was performed by using a domestic microwave oven. The polymerization reaction proceeded rapidly, compared with the conventional solution polycondensation and was completed within 10 min, producing a photoactive poly(amide-imide) in a quantitative yield. The resulting polymer was characterized by IR, ¹H NMR and TGA techniques. Thermogravimetric analysis indicated that polymer 9 was thermally stable in nitrogen atmosphere. In addition the initial decomposition temperature, 5% and 10% weight loss (T5, T10) were 284, 356 and 408 °C. The residual weight percent at 700 °C was 51.5%, which shows it is moderately thermally stable. Fluorescence properties of polymer 9 were investigated in several solvents. The ideal concentration of each case was determined by fluorescence self quenching phenomena. Also the self quenching mechanism was studied according to the specific behavior of the polymer in different solvents.     

Polymerization of 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L‐leucine) diacid chloride with aromatic diamines by microwave irradiation

A new facile and rapid polycondensation reaction of 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L‐leucine) diacid chloride (1) with several aromatic diamines, including benzidine (2a), 4,4′‐diaminodiphenyl methane (2b), 1,5‐diaminoanthraquinone (2c), 4,4′‐sulfonyldianiline (2d), 3,3′‐diaminobenzophenone (2e), P‐phenylenediamine (2f), 2,6‐diaminopyridine (2g), 4,4′‐diaminobenzophenone (2h), 2,4‐diaminotoluene (2i), and 4,4′‐diaminodiphenylether (2j), was developed with a domestic microwave oven in the presence of a small amount of a polar organic medium such as o‐cresol. The polymerization reactions proceeded rapidly compared to conventional solution polycondensation and finished within 12 min, producing a series of optically active poly(amide‐imide)s with quantitative yields and high inherent viscosities of 0.50–1.93 dL/g. All of the polymers were fully characterized by IR, elemental analyses, and specific rotation. Some structural characterization and physical properties of these optically active poly(amide‐imide)s are reported. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1154–1160, 2000     

Influence of Nanoparticle Processing on the Thermoelectric Properties of (BixSb1−X)2Te3 Ternary Alloys

The synthesis of phase-pure ternary solutions of tetradymite-type materials (Bi_xSb_1−x)₂Te₃ (x=0.25; 0.50; 0.75) in an ionic liquid approach has been carried out. The nanoparticles are characterized by means of energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and transmission electron microscopy. In addition, the role of different processing approaches on the thermoelectric properties - Seebeck coefficient as well as electrical and thermal conductivity - is demonstrated.     

Cooling of an electronic board situated in various configurations inside an enclosure: lattice Boltzmann method

Natural convection heat transfer in a square cavity induced by heated electronic board (as a thin plate at constant temperature) is investigated using the lattice Boltzmann method. Lattice Boltzmann simulation of natural convective heat transfer in a cavity in the presence of internal straight obstacle has not been considered completely in the literature and this challenge is generally considered to be an open research topic that may require more study. The present work is an extension to our previous paper (see Nazari and Ramzani in Modares. Mech. Eng. 11(2):119–133, 2011) in which the effects of position and dimensions of obstacle on the flow pattern and heat transfer rate are completely studied. A suitable forcing term is represented in the Boltzmann equation. With the representation, the Navier–Stokes equation can be derived from the lattice Boltzmann equation through the Chapman-Enskog expansion. Top and bottom of the cavity are adiabatic; the two vertical walls of the cavity have constant temperatures lower than the plate’s temperature. The study is performed for different values of Grashof number ranging from 10³ to 10⁵ for different aspect ratios and position of heated plate. The effect of the position and aspect ratio of heated plate on heat transfer are discussed and the position of the obstacle in which the maximum rate of heat transfer is investigated in both vertical and horizontal situation. The obtained results of the lattice Boltzmann method are validated with those presented in the literature.