Elastic properties of tellurite glasses

Elastic properties of binary and ternary tellurite glass systems of the composition (in mol%) (100-x) TeO2 - x Nb2O5, and (100-x) TeO2 - 0.5x (Nb2O5 + Li2O) were calculated from the measured densities as well as from longitudinal and shear ultrasonic velocities at room temperature. Ultrasonic velocity measurements were taken at 4 MHz ultrasonic frequency using the pulse echo technique. Elastic moduli, and Debye temperature calculated from experimental data and calculated theoretically using the bond compression model were used to obtain quantitative details about the structure of these glasses. The effect of adding either Nb2O5 alone or Nb2O5 and Li2 on the elastic moduli was investigated in terms of the number of network bonds of the glass systems. The average atomic ring size of the network was also calculated and it was found that it depends on the concentration of the modifiers. The obtained results show that these glasses become more stable and compact when modified with Nb2O5 or with Nb2O5 and Li2O, which increases the elastic moduli in the two systems

Fabrication of ZnO and ZnO:Sb Nanoparticles for Gas Sensor Applications

ZnO and Sb-doped ZnO nanoparticles were successfully prepared using sol-gel technique. Different concentrations of triethanolamine (TEA) were utilized as the preparation procedure to act as complexing agent that enhances the doping probability of the formed Sb-doped ZnO nanopowder. Thick films of the prepared nanopowders were fabricated with spinner coating. Morphological characteristics, phase structure, chemical composition, thermal stability, and optical properties of the prepared nanopowders were measured and analyzed. The average crystallite size of ZnO and ZnO:Sb powders ranged between 19–28 nm according to the XRD calculations and TEM observations. The gas sensitivity of the homemade devices based on Sb-doped ZnO nanoparticles towards O2 and CO2 gases as a function of temperature was measured and compared with undoped ZnO films. The gas sensitivity of the films was greatly improved after doping with Sb and reached its maximum value of ~86% for O2 gas at 93:7 wt% of Zn:Sb

Synthesis, surface properties and biological activity of N,N,N-tris(hydroxymethyl)-2-oxo-2-(2-(2-(alkanoyloxy) ethoxy)ethoxy) ethanaminium chloride surfactants

A new series of some cationic surfactants were synthesized namely: 2-(2-(2-(dodecanoyloxy)ethoxy)ethoxy)-N,N,N-tris(hydroxymethyl)-2-oxoethanaminium (DDAC); N,N,N-tris(hydroxymethyl)-2-oxo-2-(2-(2-(tetradecanoyloxy) ethoxy)ethoxy) ethanaminium (TDAC) and N,N,N-tris(hydroxymethyl)-2-oxo-2-(2-(2-(hexadecanoyloxy)ethoxy)ethoxy)ethanaminium (HDAC). The chemical structures of the synthesized cationic surfactants were confirmed using FT-IR and 1H-NMR spectroscopies. The surface tension of the synthesized cationic surfactants was measured at 25, 40 and 55 °C. The surface parameters were determined from the surface tension measurements. The emulsification power and foaming power measurements showed the applicability of these surfactants in the oil field. The biological activity of the synthesized surfactants was measured against pathogenic bacteria (Staphylococcus aureus and Escherichia coli) and fungi (Candida albicans and Aspergllus niger) using inhibition zone diameters. The obtained data revealed that the dodecanoate derivative (DDAC) has more antimicrobial activity against the investigated microorganisms than tetradecanoate and hexadecanoate derivatives (TDAC and HDAC)

Optical Properties of In-Ge-Se Thin Films

Effect of composition and annealing temperature on the optical properties of In 8 Ge x Se 92-x ( 14 ≤ x ≤ 25.5) thin films deposited by electron beam from bulk samples prepared using melt quench technique are investigated and discussed. All films have amorphous structure. It was found that the electronic energy gap E g increases with increasing Ge contents and has an ubrupt change at coordination number Z≥2.65. The ratio of free carrier concentration to the carrier effective mass ( N/m * ) and the high frequency dielectric constant ε ∞ showed also uprupt change at Z ≥2.65. The optical relaxation time τ found to have a minimum value at Z = 2.65. The optical energy gap E g found to be affected by annealing