Chemical/Physical Characterization of Nigerian Honey

Abstract: The TXRF and infrared spectrophotometer techniques were used for the characterization of Nigerian honey. The elemental concentrations and the functional groups present in Nigerian honey samples from five locations in the Southwest and Southeast of Nigeria were determined. Twelve elements- K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br and Rb- were detected. The honey samples were quite rich in minerals. Potassium was the most abundant trace element in the honey (range 1100- 2700 ppm) followed by Ca (range 152- 362 ppm) and Fe range 136- 407 ppm). There were no significant differences in the elemental contents of honey from the different locations. The infrared spectrophotometer results showed the honey sample to be a mixture of many compounds including carboxylic acids, aldehydes, alkynes, nitrites, alkynes an ethers. Other physical properties- colour, pH, refractive index, moisture and ash contents- were also determined. Key words: Honey, TXRF, infrared spectrophotometer, elemental concentrations, functional group

Spray Pyrolysis Deposition and Characterisation of Dielectric SnO2 Thin Films

Dielectric and optical dispersion properties of thin films of SnO2 deposited via spray pyrolysis were investigated. These properties are fundamental to new applications of SnO2 in energy storage and pressure sensing. The composition and thickness of the films were determined using the Rutherford Backscattered Spectroscopic mode of the Pelletron Tandem Accelerator. X-ray diffraction (XRD) technique and scanning electron microscope (SEM) were used to examine the crystal structure and surface morphology of the films. Optical transmission data were analyzed to obtain the optical band gap, dispersion parameters, and dielectric constants. The analyses showed that the films were polycrystalline in nature with the tetragonal rutile crystal structure. It was also observed that annealed films increased in thickness compared to the asdeposited samples. The Urbach tail width of the annealed sample also decresed from 293 to 252 meV indicating an improvement in crystallinity with heat treatment. The refractive index dispersion in the visible region analyzed in terms of long wavelength single-oscillator Sellmier approximation was in the range 1.9 -3.0. The zero and high-frequency dielectric constants were evaluated. The values of these constants could be a justification for further exploration of SnO2-based materials for charge storage and capacitive pressure sensing. Keywords: pyrolysis, dielectric, refractive index, thin film

Original Article Invasive bacteria isolates from children with severe infections in a Nigerian

Background: Little information is available about the aetiology and epidemiology of serious bacterial infections in Nigeria. This study determined bacterial isolates from blood and cerebrospinal fluid (CSF) of children presenting in the emergency room of a teaching hospital in Nigeria. Method: From October 2005 to December 2006, children aged two to 60 months presenting with signs of acute systemic infections were recruited. Blood culture and CSF specimens were collected and processed using standard microbiological protocols. Data were analysed using SPSS version 11 software. Results: Two hundred and two blood and 69 CSF samples were cultured. Fifty-five (27%) of the blood cultures yielded Gram-negative bacilli and Gram-positive cocci in almost equal proportions. The most common isolates from the blood cultures were Staphylococcus aureus, 26 (12.9%) and atypical coliforms, 13 (6.5%). Others are Klebsiella spp, 3 (1.5%); Klebsiella pneumonia, 2 (1.0%); Escherichia coli, 3 (1.5%); Enterobacter agglomerans, 2 (1.1%); Proteus mirabilis, 2(1%); Pseudomonas spp, 2 (1.0%); Haemophilus influenza, 1 (1.0%); and Coagulase-negative Staphylococcus, 1 (1.0%). Fourteen out of 67 (20.9%) of the CSF samples yielded bacterial isolates: Streptococcu