Nano Mg(1-x)Ni(x)Al2O4 spinel pigments for advanced applications.

Nano Mg(1-x)Ni(x)Al2O4 spinel pigments were synthesized via polymeric combustion technique upon heat treatment at 210 °C. Citric acid in the presence of ethylene glycol polymer, with mass ratio of 60:40, was successfully used as a host network for the synthesis process. The obtained spinel was calcined at different temperatures; 300-1200°C and investigated by thermal analysis (TG-DTG/DTA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). UV-Vis and diffuse reflectance spectroscopy (DRS) using CIE-Lab/parameters methods have been used for color measurements. The addition of colored pigment on different types of glazes was studied. The results revealed that NiMgAl2O4 spinel beside MgNiO phases were crystallized with particle sizes of 9-21 nm at 600 °C and 52-180 nm at 1200 °C. All prepared samples exhibited green to pale green colors due to the inclusion of Ni(2+) inside the spinel structure. The pale green color intensity increased with increasing calcination temperature. The prepared pigment was suitable to convert commercial and opaque glazes to color product to be used in different applications.

Effect of nanospinel additions on the sintering of magnesia-zirconia ceramic composites.

Nanocrystalline magnesium aluminate (MA) spinel powder produced through a coprecipitation method and calcined at 900°C for 1 h was added to magnesia-zirconia composite in the range of 0-25 mass % and sintered at 1600°C for 2 h. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used for studying the microstructure and the phase composition of the sintered composites. Bulk density, apparent porosity, volume shrinkage, and Young's modulus of the sintered composites were also investigated. The results revealed that the nanospinel addition up to 20 mass % increases the sintering ability and Young's modulus of the composite bodies. Microstructure showed that the presence of nanospinel and zirconia in the triple point between magnesia grains closed the gaps in the ceramic matrix and enhanced the compactness of the composites.

Effect of surfactant types and their concentration on the structural characteristics of nanoclay.

A series of organo-modified nanoclays was synthesized using three different surfactants having different alkyl chain lengths and concentrations [0.5-5.0 cation exchange capacity (CEC)]. These surfactants were Ethanolamine (EA), Cetyltrimethylammoniumbromide (CTAB) and Tetraoctadecylammoniumbromide (TO). The obtained modified nanoclays were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) and compared with unmodified nanoclay. The results of XRD analysis indicated that the basal d-spacing has increased with increasing alkyl chain length and surfactant concentration. From the obtained microstructures of these organo-modified nanoclays, the mechanism of surfactant adsorption was proposed. At relatively low loading of surfactant, most of surfactant entered the spacing by an ion-exchange mechanism and is adsorbed onto the interlayer cation sites. When the concentration of the surfactant exceeds the CEC of clay, the surfactant molecules then adhere to the surface adsorbed surfactant. Some surfactants entered the interlayers, whereas the others were attached to the clay surface. When the concentration of surfactant increased further beyond 2.0 CEC, the surfactants might occupy the inter-particle space within the house-of-cards aggregate structure.

Reproductive efficiency of Egyptian buffaloes in relation to oestrous detection systems.

A total of 57 buffalo cows were divided into two groups and subjected to different intensities of oestrous detection. In the first group (G1), oestrus was checked at 6-h intervals, four times daily starting at 0600 h as compared to twice daily in the second group (G2) at 0800 h and 1500 h. The year was also divided into two seasons: cool from November to April; and hot from May to October. Ovulatory activity was monitored by measuring progesterone concentrations in blood serum. Samples were obtained every 3 or 4 days post-partum until conception was confirmed. More frequent detection practices produced shorter intervals for all of the reproductive parameters. Calving interval was less for cows in G1 in the cool season (363.5 +/- 16.0 vs. 400.3 +/- 14.3 days) than in the host season (387.0 +/- 15.3 vs. 441.5 +/- 14.3 days). Oestrous detection efficiency was higher (P < 0.01) in G1 in both seasons. Season of calving produced a significant effect (P < 0.05) on the number of services per conception. The cool season calvers had better reproductive performance than cows calved during the hot season.