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Due to the depletion of world petroleum reserves and increased environmental concerns, recent interest in alternative source for petroleum-based fuels has been developed. Biodiesel arose as the potential candidate for a diesel substitute due to the similarities it has with petroleum-based diesel. Chemically biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feedstock like vegetable oils and animal fats. It is produced largely by transesterification in which oil or fat is reacted with a monohydric alcohol in the presence of a catalyst. In this research, biodiesel was produced from groundnut oil and shea butter oil using homogeneous catalyst under varying operating conditions such as temperature, concentration of NaOH(s) and time of reaction, and the conditions which gave the optimum biodiesel yield were obtained. The best operating temperature and catalyst concentration for the transesterification of both oils were found to be 70℃ and 1% catalyst (NaOH) respectively. While the optimum reaction time was found to be 75 and 60 min for shea butter and groundnut oils respectively. The study showed that both sh

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The synthesis and characterisation of Zn-Al hydrotalcite-like compounds intercalated with sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) have been investigated in details. The synthesis has been carried out following calcination-regeneration method. The organic modification was intended to derive hydrotalcite-like compounds appropriate for various applications such as polymer-HTlcs nanocomposite, and as scavengers of organic pollutants. The inorganic organic hybrid materials were characterised by a range of techniques such as XRD, XRF, FT-IR, TG DTA, and SEM. Characterisation data showed that pure phase of the series of hydrotalcites has been synthesised and cation molar ratios conform well to the expected ratios of Zn/Al cations in the different samples. Varying the ratios of the Zn2+/Al3+ results in distinguishing properties e.g. charge density, crystallinity, amount and orientation of anions in the interlayers and morphology. TGA showed differences in the temperature at which transitions were completed

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Caesalpinia coriaria has been screened for their Phytochemicals and antimicrobial activity against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus spp. and Salmonella spp. The tannins extracted using water, acetone and methanol exhibited antimicrobial activity against Staphylococcus aureus, Bacillus subtillis, Escherichia Coli, Proteus vulgaris, Shigella dysenteriae and Candida albicans. The results showed that methanol extracts have more inhibitory effect than the other extracts. However, in this study the focus is on water extract which is the solvent used traditionally. The highest zone of inhibition of the water extract was found to be 22 mm of Bacillus subtillis compared with a standard Sparfloxacin 10µg/disc which gave 23 mm of Bacillus subtillis. Phytochemicals screening including alkaloids, tannins, saponin, steroid, terpenoids, flavonoid, carbohydrates, and glycosides were present. The proximate analysis of the extracts - moisture content, total soluble, pH, and total solid and total insoluble gave 4.00%, 50.88%, 5.59, 96.00% and 45.12% respectively. . It may be concluded that Caesalpinia coriaria pods contain bioactive compounds of potentially therapeutic and prophylactic significance and thus could be a promissory candidate for drug development.

Abstract

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Zinc oxide ceramic varistors were realized by doping ZnO with small quantities of MnO2 and PbO. The preparation technique of Direct Mixing of Constituent Phases (DMCP) was used. The samples were pelletized at a pressure of 1.24 X 103 N/cm2 and sintered in ambient atmosphere at a temperature of 850°C for a period of 36hours. They were characterized by measuring the current-voltage response to evaluate the non-ohmic behaviour. Breakdown threshold voltages of 2.02 X 103 V/m and 4.80 X 103 V/cm were recorded at currents 1.05 A/cm2 and 1.20A/cm2 respectively. Microstructural analyses were carried out using x-ray diffraction and scanning electron microscopy techniques. The XRD spectra re vealed the formation of structures and polymorphs of the additives in the sample while the SEM mi crographs revealed the sizes, types and distribution of grains in the matrix. The grain sizes for the re spective sample types were obtained as 1.621 µm and 1.020 µm. The microstructural analysis gave good correlation with the electrical response of the varistor samples.

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The physical properties of clay deposits located in Mailolo in Hadejia Local Government Area, Gwaram in Ringim Local Government Area and Firimo in Birnin Kudu Local Government Area of Jigawa State were assessed for use as refractory materials. Jigawa State is blessed with abundant deposits of clay, which is mostly used for the production of potteries, mud houses and structures. Samples of clays were collected from the deposits and test specimens were prepared for evaluating their physical properties to determine whether they will be suitable for refractory applications. The results of the assessment showed that Firimo, Mailolo and Gwaram possesses cold crushing strength values of 44.6 kg/cm2, 281.13 kg/cm2 and 223.6 kg/cm2 ; bulk strength values of 1.93 g/cm3, 1.73 g/cm3 and 1.41 g/cm3; moisture content values of 2.20% , 3.70% and 4.30%; percentage clay content values of 32.83%, 64.66% and 83.12% ; water absorption values of 3.00% ,4.00% and 5.00% and refractoriness values of 12500C, 12000C and 12000C respectively. Due to their low refractoriness, thermal shock resistance and apparent porosity the clays will only be suitable for low temperature refractory applications such as insulation, bakery oven lining, patching materials, slag pot and ladles lining etc.

Abstract

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A frequently referenced component in the prevention of diabetic foot problems is the use of therapeutic footwear. Thus, footwear should be designed to relieve pressure areas, reduce shock and shear forces and be able to accommodate foot deformities by supporting and stabilizing them. There is however lack of adequate knowledge about the role of footwear and multidisciplinary approach in the management of foot related problems among diabetic patients and health care providers. This study is the first of its kind to be done in Nigeria with an aim to develop a design framework that would help to identify appropriate footwear designs for people suffering with diabetes. The proposed design framework was developed based on information gathered through questionnaires and interview surveys of diabetic patients and medical doctors in Nigeria respectively. The design framework shows three step-by-step procedures for provision of appropriate footwear to people suffering with diabetes. Product Design Specification was also formulated to determine key elements that could be considered in the design and selection of appropriate materials for diabetic footwear manufacture. Three functional prototypes (footwear) were made and used to test various usability aspects of the product with the prospective users. It was concluded that the high rate of amputation reported amongst diabetic patients could be drastically reduced through effective use of the proposed design frame work. Finally, limitations of this work and areas that would require further research were also outlined.

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The flow patterns during oil-water flows were investigated in two acrylic pipes that had different diameters, 38 mm ID and 14 mm ID respectively. Water (ρ = 1000 kgm-3, μ = 0.001 kgm-1s-1) and Exxsol D140 oil (ρ = 830 kgm-3, μ = 0.0055 kgm-1s-1) were used as test fluids, while the patterns were recorded with a high speed camera. Dispersed and rivulet flows were seen in the small pipe but not in the large one at the conditions studied. The dual continuous pattern appeared in both pipes but, with different characteristics. Larger drop sizes and smoother interface were seen in the smaller pipe. Double-wire conductance probes were used to collect time-series records of the oil-water interface variation during stratified flow in the pipes. Data was collected at 256 Hz (or 512 Hz) for up to 4 min. Following de-trending and normalisation, the signal was found to be stationary and normal. Power spectra were computed via the auto-correlation function. Low-frequency contributions (due partly to the pumps) were seen in both pipes. In the large pipe, contributions were in the range 20 – 50 Hz and their normalised power increased with the mixture velocity. These higher frequencies were attributed to the fluctuations and roughness of the interface, notorious in the large-diameter pipe during stratified flow. In contrast, the interface in the small pipe was smooth.

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In this research, Atili (blackdate) oil (Canarium Schweinfurthii) was extracted from the pulp using aqueous biphasic system (ABS) prepared from fixed concentration (40%) of polyethylene glycol (PEG) and varying concentrations of salt (di-sodium hydrogen phosphate (Na2HPO4)) at 10%, 20%, 30%, 40% and 50% respectively. The partitioning of the atili oil to the PEG-rich phase for the various combinations of the salt concentration with the fixed PEG concentration were compared and the extracted atili oil characterized. The extraction process was carried out by preparing the aqueous biphasic systems with the varying salt concentrations and placing the enclosed pulp of atili fruit inside the ABS prepared until the oil partitions to the PEG-rich phase. The ABS prepared from the salt concentration at 20% was found to give the best system for extracting atili oil with a yield of 43.50 mls of atili oil /100g of atili pulp. Lastly, the acid value , saponification value, free fatty acid and ester values were found to be 0.22, 116.13, 0.11 and 115.92 respectively.

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Atili (blackdate) oil was bleached in this research using three different adsorbents; acidic fuller’s earth, activated carbon, and the mixture of fuller’s earth and activated carbon. The adsorbents were compared to give the most suitable of the three. The bleaching process was carried out by agitation of varying amounts of the different adsorbents at 80oC and a contact time of 45mins. The bleaching data were fitted to Langmuir and Freundlich isotherms; bleaching with fuller’s earth gave good fits to both. Fuller’s earth was observed to be most suitable for bleaching of Atili (blackdate) oil, giving a colour removal of 88.25%, which was followed by activated carbon with a colour removal of 85.95% and lastly the mixture, with colour removal of 85.34% all with 2g of adsorbent. Finally, photometric colour was determined as the average absorbance between 420 and 800 nm

Abstract

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Subgrade materials from Master Test Section (MTS) 1 were tested to obtain their physical properties. Three samples each from the MTSs making a total eighteen (18) samples were obtained and subjected to laboratory test to determine their basic physical properties. Testing include particle size distribution, Atterberg limits and specific gravity tests. The samples were classified according to American Association of State Highway and Transportation Officials (AASHTO) and the Unified Soil Classification System (USCS). The AASHTO soil classification shows that the subgrade soil samples obtained from the MTS 1 were either clayey soil (A-6 and A-7-6) or silty soils (A-4, A-5 and A-2-4). The AASHTO soil classification generally showed that the subgrade samples were “Fair to Poor” in subgrade properties for use as construction materials. The USCS soil classification indicated that most of the samples were lean clay soil with gravel (CL) except few that were either clayey gravel (GC) or clayey sand (SC). This showed that the subgrade samples were mostly clay soil.

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The aim of the work presented in this paper is to evaluate and develop a framework for reliability analysis of distribution system modeling and simulation using Petri-Nets. The problem of detecting, isolating and restoring fault events in dynamic systems modeled is considered. As the complexity of power system increases, fault diagnosis become very difficult task therefore necessitate the development of PN to anchor onto power system in order to tackle and overcome these situation. A sample power system network which has 2 sources, 4 buses, 10 over current relays, 5 circuit breakers and 2 distribution lines connected loads is used as test network. The modeled network is then simulated with five fault cases. Results of these simulations are given in order of the PN firing sequence as follows: M1 = (1; 0; 0; 0; 0; 0; 0); M2 = (0; 1; 0; 0; 0; 0; 0); M3 = (0; 0; 1; 1; 0; 0; 0); M4 = (0; 0; 1; 0; 1; 1; 0); M5 = (0; 0; 1; 0; 1; 0; 1) and M6 = (1; 0; 0; 0; 0; 0; 0).It is shown from five cases that the faulted power system elements are diagnosed accurately by using the Petri nets based fault diagnosis models analytical and simulation.

Abstract

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Alkyl ester derivatives of palm kernel oil have been prepared for use as bio-dielectrics in oil filled High Voltage (HV) electric equipment. Electrical conduction and loss characteristics of the ester derivatives were studied to understand the behaviour of the material under applied electric field. Frequency response analyzer was used to study electrical conduction within the fluids since dielectric loss occurring at low frequencies under AC condition is dominated by mobile charge carriers. This is particularly important since power dissipation at power frequency, 50 Hz, may lead to dielectric heating. The dielectric response analyses of the samples within the range 10-3 - 104 Hz showed a constant real relative permittivity at high frequency region. When the frequency dropped below 101 Hz, interfacial polarization was observed at the electrode-liquid interface and this resulted in a significant dielectric increment in the real part of the relative permittivity at low frequencies with a negative slope greater than 1 and a frequency independent conductance (εʹ slope = -1). This is an indication of Maxwell-Wagner interfacial effect where electric double layer (EDL) is formed. The real part acquired a slope of about -1 around frequency of 10-3 Hz. This suggests that the establishment of the EDL may be tending towards steady state. This change in the low frequency dispersion could be due to the ionic species undergoing interfacial electrochemical processes, or ions of lower mobility may have contributed to the EDL formation within the frequency region. This may have limited the effect of the strongly divergent processes at the interface.

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The paper presents the results of a laboratory study on the effect of groundnut shell ash on the particle size distribution and plasticity characteristics of black cotton soil. Black cotton soil was treated with a maximum 10 % groundnut shell ash by weight of dry soil. The results show that there was a substantial reduction in the amount of fines content with higher doses of groundnut shell ash. The percentage of silt fraction in the natural soil was 91 % and on treatment with maximum 10 % groundnut shell ash content (by weight of dry soil) at optimum moisture content (OMC), the silt fraction was reduced to 1.3 %. The plasticity index increased from 38 to 75 % when treated with 10 % groundnut shell ash content by weight of dry soil. The results obtained place the soil below the Highway Research Board of America (1943) requirements of plasticity index of less than 50 %. The plasticity modulus (PM), plasticity product (PP) and the shrinkage modulus (SM) increased while the grading modulus (GM) decreased with higher doses of groundnut shell ash. However, the treated soil can be admixed with more potent stabilizer since its workability was improved by addition of 10% groundnut shell ash content by dry weight of soil.

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Biodegradable polymers can either be natural or synthetic and they have been greatly applied across fields especially in medicals due to their bioabsorbability, biocompatibility and biodegradability. A lot had been achieved through the efforts of polymer scientist in using synthetic materials in human body and this is due to the versatility and biodiversity of the materials. Synthetic biodegradable polymers in general are of greater advantage over natural materials in that they can be tailored to give a wider range of properties and have more predictable lot-to-lot uniformity than materials from natural sources. Lately, there is a large increase in the use of these polymer materials in ecological applications, packaging, and pharmaceutics and even in agriculture. Hence, researchers have also intensified efforts to make these polymer based materials eco-friendly so as to reduce the pollution problems such as blockage of drainages and littering of the environment by these polymeric materials. In this review however, we will focus on synthetic biodegradable with emphasis on their mode of degradation, applications and processing conditions.

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Chitin was isolated from locust using a standard procedure as described in literature with slight modifications. Chitosan was then synthesized from the isolated chitin by treatment with 50% concentration of NaOH, the degree of the deacetylation obtained was 64.4% using Potentiometer Titration method. Both chitin and chitosan ash content and moisture content were then analyzed. They were then characterized using FTIR, TGA, DSC and XRD and the results compared with chitin and chitosan obtained from other sources and they thus show similar physicochemical and chemical structure. Thus locust is a promising alternative source for both chitin and chitosan.