Weibull approach to brake pad wear analysis in the Nigerian market

In this study, we evaluated the wear properties of four brands of brake pad available in the Nigerian market. In particular, we assessed the tribo performance and service life of the brake pads. We purchased four commercial brands of brake pads used in light duty cars and coded them as AU, SN, TY and SM, respectively. A small piece of the brake pad lining materials was carefully chiseled from the back plates to obtain samples for the experiments. We conducted Brinell hardness tests using a tensometer and a pin-on-disc test rig to determine the coefficient of friction and the wear characteristics of the materials. We then correlated the wear on each set of brake pads with the running time and used Weibull’s equation to determine average service life. Sample TY exhibited the highest hardness value (29.09) and sample SN the lowest (10.05). The determined coefficients of friction ranged between 0.3–0.36, with sample AU exhibiting the lowest value and sample SM the highest. Sample SN showed the lowest wear rate of 3.53 × 109 g/min, while the wear rates of samples TY, AU, and SM were 5.64 × 108, 8.19 × 109, and 2.10 × 108 g/min, respectively. The relative service life of samples SN, TY, and AU were similar, with average values of 2778.09, 2725.41, and 2717.34 min, respectively, and SM had a relatively low service life (2017.82 min). We conclude that the overall performances of Nigerian brake pads do not meet all the specifications for friction materials used in road vehicle brake linings and pads

Dyslipidemia in HIV-1 Infected Subjects with Short Term Usage of Highly Active Antiretroviral Therapy (HAART) in Benin City, Nigeria

This study aimed to investigate the short-term effects of Highly Active Antiretroviral Therapy (HAART) (stavudine, lamivudine and nevirapine) on serum lipids of HIV-1 positive subjects in Benin City, Nigeria. Test group 1 (n=78) and test group 2 (n= 71) comprised HIV- 1 seropositive individuals on HAART for a period of one to three months; and five to six months respectively. Fifty five newly diagnosed HIV-1 positive subjects naïve to HAART served as control group 1 and sixty apparently healthy HIV-1 seronegative individuals served as control group 2. The blood samples obtained were analyzed for total cholesterol, triglycerides, low-density lipoprotein and high-density lipoprotein using standard enzymatic methods. Total cholesterol of test group 2 (214.0±6.43mg/dL) was not significantly different from Test group 1 (202.4±5.09mg/dL), both were however significantly higher than control group 1 (159.3±5.09mg/dL) and control group 2 (101.6±3.76 mg/dL). Triglyceride concentration of test group 2 (106.6+11.95mg/dL) was not significantly different from test group 1 (135.8+9.88mg/dL), but were significantly different from control groups 1 and 2 (125.1+3.35mg/dL and 104.6+3.08mg/dL) respectively. Dyslipidemia could set in from 1 to 6 months of HAART usage in HIV-1 Positive subjects hence serum lipids should be monitored as early as one month of HAART commencement.Keywords: Dyslipidemia, HIV chemotherapy (HAART), Lipid profile, HI

Impact of Nutrients, Aeration and Agitation on the Bioremediation of Crude Oil Polluted Water Using Mixed Microbial Culture

Abstract. Crude oil polluted water was treated using a bioremediation strategy encompassing natural attenuation and biostimulation using a mixed microbial culture of Aspergillus niger and Pseudomonas aeruginosa. Four (4) samples of petroleum hydrocarbon polluted water; Control (no nutrient), A (nutrient from NPK 15:15:15), B (nutrient plus aeration), and C (nutrient, aeration and agitation) were monitored for 8 weeks for bioremediation indicating parameters such as Biological Oxygen Demand (BOD), Dissolved Oxygen (DO), Total Hydrocarbon Content (THC) and pH. The results obtained showed an increase in DO levels of 86.4, 87.0 and 87.5 % for samples A, B, and C respectively. The BOD of the samples was observed to decrease in the course of bioremediation with reduction levels of 98.6, 98.7 and 98.8% recorded for samples A, B, and C respectively. Reductions in THC corresponded to 92.3, 93.6, and 94.4% respectively for samples A, B and C. The pH of all samples fell within the acceptable limit of 6-9 as stipulated by regulatory agencies such as the Federal Environmental Protection Agency (FEPA) and the department of petroleum resources (DPR). The final values of BOD and THC fell within the values of 30 and 10 mg/l respectively stipulated by FEPA and DPR with the exception of sample A which had a final THC value of 14 mg/l

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Volume 2, Issue 2 Pages 43 -73 Impact of Nutrients, Aeration and Agitation on the Bioremediation of Crude Oil Polluted Water Using Mixed Microbial Culture Comparative in-vitro Studies on Native Plant Species at Heavy Metal Polluted Soil Having Phytoremedi

Abstract. Crude oil polluted water was treated using a bioremediation strategy encompassing natural attenuation and biostimulation using a mixed microbial culture of Aspergillus niger and Pseudomonas aeruginosa. Four (4) samples of petroleum hydrocarbon polluted water; Control (no nutrient), A (nutrient from NPK 15:15:15), B (nutrient plus aeration), and C (nutrient, aeration and agitation) were monitored for 8 weeks for bioremediation indicating parameters such as Biological Oxygen Demand (BOD), Dissolved Oxygen (DO), Total Hydrocarbon Content (THC) and pH. The results obtained showed an increase in DO levels of 86.4, 87.0 and 87.5 % for samples A, B, and C respectively. The BOD of the samples was observed to decrease in the course of bioremediation with reduction levels of 98.6, 98.7 and 98.8% recorded for samples A, B, and C respectively. Reductions in THC corresponded to 92.3, 93.6, and 94.4% respectively for samples A, B and C. The pH of all samples fell within the acceptable limit of 6-9 as stipulated by regulatory agencies such as the Federal Environmental Protection Agency (FEPA) and the department of petroleum resources (DPR). The final values of BOD and THC fell within the values of 30 and 10 mg/l respectively stipulated by FEPA and DPR with the exception of sample A which had a final THC value of 14 mg/l