Effects of Concentration and Catalyst on the Kinetics of Biogas Production from Cattle Dung at Thermophilic Temperature

Five different reactors (Ra, Rb, Rc, Rd and Re) of equal capacity (500cm3 each) were constructed and connected to a gas-collecting device. For the investigation of the effect of concentration on biogas production (uncatalysed reaction), different concentrations of reactant (20g/250cm3, 30g/250cm3, 40g/250cm3, 50g/250cm3 and 60g/250cm3) prepared from cattle dung were respectively placed in Ra, Rb, Rc, Rd, and Re, and anaerobically fermented at thermophilic temperature (370C) for 16days. For the investigation of the combined effect of concentration and catalyst (catalysed reaction), parallel set ups were made, but in this case, 1.0g, 1.5g, 2.0g, 2.5g, and 3.0g of yeast were respectively added to the reactants (slurries) in Ra, Rb, Rc, Rd, and Re, which were also anaerobically fermented at 370C for 16days. The reactors and their contents for both the catalyzed and uncatalyzed reactions were made in triplicate and the mean (average) volume of biogas collected in each of the reactors were evaluated. The average volumes of biogas obtained were used for the kinetics studies, where the rate of biogas production, the rate constant for biogas formation from the substrate (cattle dung), the rate of catalyst substrate unstable complex formation, the fraction of total catalyst that involved in the formation of complex with substrate, the concentration of excess (free) catalyst in the slurry, the rate of substrate transformation into biogas and the saturation constant of the catalyst added to each slurry was evaluated using the appropriate equations. The research revealed that, addition of catalyst to the slurries,  enhanced biogas production; at a certain point, the volume of biogas produced, the rate of biogas formation, the rate of catalyst substrate unstable complex formation and the rate of substrate transformation into biogas were directly proportional to the concentrations of the reactants and catalyst; the rate constants for reactions (catalyzed and uncatalyzed) were inversely proportional to the concentrations of reactants and the catalyst added; the fractions of the total catalyst that involved in the formation of unstable complex  with substrate in Ra, Rb, Rc, Rd, and Re were 0.95g, 0.97g, 0.98g, 0.98g, and 0.98g, respectively; the concentrations of the excess catalyst in Ra, Rb, Rc, Rd, and (g/cm3) were 0.05, 0.53, 1.02, 1.52 and 2.02, respectively and; the saturation constants (g/g) of the catalyst added to the slurries in Ra, Rb, Rc, Rd, and Re were 0.0476, 0.0484, 0.0488, 0.0490, and 0.0492, respectively. The research also revealed that the reactions (catalyzed and uncatalyzed) carried out obeyed first order rate law equation. Key-words: Biogas; cattle dung; anaerobic fermentation; concentration; catalyst; thermophilic temperature

EVALUATION OF CHEMICAL CONDITION OF MUNICIPAL SOLID WASTE BEING USED IN SOIL FERTILITY MAINTENANCE IN ZARIA, NIGERIA

This paper reports the results of a study conducted to evaluate the chemical condition and heavy metal contents of MSW being used in soil fertility maintenance by local farmers in Zaria urban area. Samples of the wastes were collected from major dumpsites in six major areas of the town (namely Muchiya, Sabon Gari, Gaskiya, Samaru, Tudun Wada and Gyallesu). The wastes were sorted out to obtain the solid fractions which were digested and analysed for pH, N, P, C, Ca, Mg, K, Na, CEC, BS, Cu, Zn, Mn, Cr, Cd, Ni and Pb using standard procedures. The results obtained indicate that pH values range between 5.60 and 9.50, N 0.39 to 0.70%, P 29.32 to 56.0 ppm, C 2.35 to 4.63 %, Ca 6.20 to 23.44 Cmol/kg, Mg 2.16 to 13.46 Cmol/kg, K 3.82 to 9.32 Cmol/kg, Na 1.22 to 7.57 Cmol/kg, CEC 22 to 58.56 Cmol/kg, % BS 82.25 to 90.02, Cu 0.84 to 7.50 mg/kg, Zn 10.20 to 25.00 mg/kg, Mn 32.0 258.0 mg/kg, Fe, 62.0 to 864 mg/kg, Cr 1.30 top 33.36 mg/kg, Cd 1.45 to 6.20, Ni 1.20 to 53.35 and Pb 1.50 to 13.35. The results obtained thus indicate that the fertility rating of the wastes in the various areas is high to very high, except that of sodium which is rated as low. While Zn, Fe, Cr and Pb exist in high proportions and the remaining heavy metals exist in comparatively lower proportions in the waste samples. The soil fertility maintenance and public health implications of these results are discussed in light of the long term implications of sodium and heavy metal accumulations in soils receiving urban wastes applications in the area

Ground receiving station reference pair selection technique for a minimum configuration 3D emitter position estimation multilateration system

Multilateration estimates aircraft position using the Time Difference Of Arrival (TDOA) with a lateration algorithm. The Position Estimation (PE) accuracy of the lateration algorithm depends on several factors which are the TDOA estimation error, the lateration algorithm approach, the number of deployed GRSs and the selection of the GRS reference used for the PE process. Using the minimum number of GRSs for 3D emitter PE, a technique based on the condition number calculation is proposed to select the suitable GRS reference pair for improving the accuracy of the PE using the lateration algorithm. Validation of the proposed technique was performed with the GRSs in the square and triangular GRS configuration. For the selected emitter positions, the result shows that the proposed technique can be used to select the suitable GRS reference pair for the PE process. A unity condition number is achieved for GRS pair most suitable for the PE process. Monte Carlo simulation result, in comparison with the fixed GRS reference pair lateration algorithm, shows a reduction in PE error of at least 70 % for both GRS in the square and triangular configuration

Effect of oral administration of ethanolic extract of Tapinanthus globiferus A. rich on liver function in rats

The effects of ethanol extract of Tapinanthus globiferus in the liver of rats were evaluated on serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total protein (TP), total bilirubin (TB) and conjugated bilirubin (CB) while histological analysis was evaluated on section of liver after 28 days of oral administration. The oral LD50 of the extract in rats was found to be greater than 5,000 mg/kg body weight. The biochemical analysis revealed no significant changes (p > 0.05) in serum levels of AST, ALT, ALP and TP at all doses treated (87.5, 175 and 350 mg/kg) but there was significant (p < 0.05) evaluation of serum TB at higher dose and significant (p < 0.05) dose dependent increase in CB when compared with control. The photomicrograph of transverse section of the liver treated with doses of 175 and 350 mg/kg showed areas of fibrosis at 100 magnifications while no effect was observed at 87.5 mg/kg body weight. This work revealed that, Tapinanthus globiferus extract has no toxic effect on the liver of rats after short and low dose administration but can cause sign of liver damage at higher dose.Key words: Tapinanthus globiferus, Biochemical, Ethanol, Histological, Photomicrograp

Time of arrival 3-D position estimation using minimum ADS-B receiver configuration

The location from which a signal is transmitted can be estimated using the time it takes to be detected at a receiver. The difference between transmission time and the detection time is known as time of arrival (TOA). In this work, an algorithm for 3-dimensional (3-D) position estimation (PE) of an emitter using the minimum receiving stations configuration was developed. The TOA measurements estimated from three automatic surveillance dependent broadcast (ADS-B) receivers are used to evaluate the performance of the PE algorithm. The result shows that the triangular ADS-B receiver configuration is capable of 3-D PE for emitter locations within 190 km coverage radius and that the altitude estimation error is 2 km higher than the horizontal coordinate estimation error. Within the 3-D PE coverage of the ADS-B receiver, the maximum horizontal and altitude error expected are 0.12 km and 2.2 km respectively.Keywords: TOA, ADS-B, position estimation, minimum configuration, surveillanc

Some behavioural studies on methanol root bark extract of Burkea africana (fabaceae) in mice

Burkea africana is a plant that belongs to then family Fabaceae; it is widely spread in tropical Africa including Nigeria. It is of valuable in ethnomedicine especially in the treatment of antidote for venomous stings and bites, cutaneous and sub cutaneous parasitic infection, convulsion and pulmonary troubles. The research was conducted to evaluate some central nervous system properties of the root bark methanol extractof B. africana in mice. It involved the following animal models: diazepam-induced sleep, hole-board and walking beam assay. Results: The methanol extract showed a significant decrease in the onset of sleep at doses of 40 mg/kg and 80 mg/kg (p<0.05); as well as produced significant increase in the duration of sleep (40 and 80 mg/kg) at p<0.05, p<0.005 respectively. The number of head dips significantly increased at 20 and 80 mg/kg (p<0.05 and 0.005 respectively). From the beam walking test for motor deficits, the result showed a significant increase in the number of foot slips at doses of 20 mg/kg (p<0.05); 40 and 80 mg/kg (p<0.005), where as there was no significant difference in the time taken to cross the two ends of the beam (time taken to complete the task). The median lethal dose (LD50) value of B. africana extract was found to be 288.5 mg/kg (i.p) in mice. The preliminary phytochemical screening revealed the presence of carbohydrates, saponins, flavonoid, aglycones, tannins, anthraquinones, cardiac glycosides, unsaturated steroids and triterpenes. Our results suggest that the B. africana extract contains biologically active compounds with potential sedative and anxiolytic properties.Key Words: Sedation, B. Africana, Diazepam, ethnomedicin

Assessment of the effect of dihydroartemisinin-sodium valproate combination on some behavioural activities in mice

Co-morbidity inevitably warrant occurrence of polypharmacy that may result in interactions or modification of either the therapeutic or toxic effect of any of the drugs employed. Malaria and epilepsy have been known to occur concurrently as such may necessitate the co-administration of two or more drugs. This study evaluated the effect of dihydroartemisinin-valproate combination on some behavioral activities related to central nervous system. The study was conducted using animal models as follows: maximal electroshock-induced seizures test in mice, diazepam-induced sleep in mice and mouse beam walking test for motor coordination deficit. Generally, the results showed that there were no statistical significant effects in the test models. Therefore, dihydroartemisinin did not significantly influence the protective effect of sodium valproate in convulsion; and did not significantly cause sedation in animals. Hence, the result of this study suggests that dihydroartemisinin-sodium valproate combination could be considered safe in seizures condition.Keywords: Dihydroartemisinin, Polypharmacy, Valproate, Drugs, Epileps

Effect of Avogadro Oil as Corrosion Inhibitor of Thermally Pre-aged Al-Si-Mg Alloy in Sodium Chloride Solution

The corrosion inhibition of thermally pre-aged Aluminium-Silicon-Magnesium (Al-Si-Mg) alloy in 3.5 % NaCl solution with natural Avogadro oil of varying concentrations has been studied using linear polarization techniques. From the results obtained, the corrosion rate decreased with an increase in Avogadro oil concentration. An inhibitor efficiency of 46.7, 58 and 71 % were obtained at 1.5, 3.0, 4.5 g/v Avogadro oil addition in a 3.5 % NaCl solution respectively for the conventional alloy. Results from the linear polarization technique indicate a higher potential value with an increase in the polarization resistance (Rp) and lower current density in the inhibited samples than the uninhibited Al-Si-Mg alloy as obtained from the Tafel plot extrapolation. There exist some levels of correlation in the inhibitor efficiency between the conventional and the thermally pre-aged Al-Si-Mg alloy/Avogadro oil in 3.5 % NaCl solution