Dielectric Properties of Filled Composites of Epoxy Resin
Pages 455-460
Fareeda Farrukh and Shahid H. Zaidi

DOI: http://dx.doi.org/10.6000/1927-5129.2014.10.60

Published: 03 October 2014

Abstract: The addition of fillers in composite of epoxies, improves the dielectric response of the epoxies. The dielectric properties of unfilled and filled composites of epoxy resins have been studied as a function of thickness in the frequency range 10^-1 Hz to 10⁵ Hz at room temperature. The response of the unfilled samples shows that the composites behave as an insulator for all thickness. In filled composites at small thickness (0.32 mm) the response shows a loss peak in low frequency regime. The peak is broader than the Debye loss peak which is obscured by the dc conductance. At frequencies greater than ω_p the response shows a well defined power law behaviour after the subtraction of C_∞. Similar behaviour has been observed at different thickness.

Antibiotic Sensitivity Pattern of Pathogenic Bacterial Isolates From Diseased Clarias gariepinus From Selected Ibadan And Ikorodu Farms
Pages 439-448
Nkechi C. Okere, A. Olubusola Odeniyi and K. Olanike Adeyemo

DOI: http://dx.doi.org/10.6000/1927-5129.2014.10.58

Published: 23 September 2014

Abstract: This study was carried out to isolate, characterise and identify bacteria from diseased Clarias gariepinus and also assess the occurrence of resistance to antimicrobial in isolated bacteria. Samples of diseased African Catfish were collected for a period of six weeks from consenting farms in Ibadan and Ikorodu in Nigeria and examined for clinical signs of disease. Pond water samples along with organs such as gills, skin, intestine, kidney and lungs from these fish were analyzed microbiologically using differential and selective media. Bacteria enumeration, identification and biochemical characterization were carried out and the physiochemical parameters of the water samples determined. All isolates were subjected to antibiotic sensitivity test using the standard Kirby-Bauer disc diffusion method. The total bacterial load for the organs ranged between 3.0 x 10⁴ (lungs sample) and 6.0 x 10⁷cfu/g (gill sample). The gills had the highest average total bacterial count, while lungs had the least. Morphologically unique bacterial isolates obtained included Salmonella (14 isolates), Pseudomonas (4 isolates), Aeromonas (2 isolates), Edwardsiella (3 isolates) and Shigella (3 isolates). These isolates displayed antibiotic resistance profile to the following: Ceftazidime (38%), Cefuroxime (77%), Gentamicin (37%), Cefixime (73%), Ofloxacin (23%), Augmentin (66%), Nitrofurantoin (58%) and Ciprofloxacin (15%). Two Salmonella isolates had multi-drug resistance pattern. This study showed that indiscriminate use of unlicensed or unapproved antibiotics for aquaculture portends significant hazards to public health therefore disease prevention is preferable through good culture and health management to ensure optimum yields and wholesome products.