Open Access Original Research Article

Effects of Organic Loading Rate on Biogas Yield in a Continuously Stirred Tank Reactor Experiment at Mesophilic Temperature

A. O. Adebayo, S. O. Jekayinfa, B. Linke

Current Journal of Applied Science and Technology, Page 1-9
DOI: 10.9734/BJAST/2015/18040

In this work, an attempt was made to study the effect of organic loading rate (OLR) on biogas yield using cow slurry as a single substrate at mesophilic (37°C) temperature in a long time experiment with Continuously Stirred Tank Reactor (CSTR). The reactor was loaded at OLR of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 goTS/l.d. Each OLR was maintained two (2) weeks before increasing it by 0.5 goTS/l.d. The experiment was run continuously for 140 days. It was observed that the biogas and methane yields decreased with increase in the organic loading rate after the reactor had attained stability. Both biogas yield and CH4 in the biogas decreased with the increase in OLR. For OLR in the range of 2.0 g (oTSl-1d-1) – 5.0 g (oTSl-1d-)1, biogas and methane yields obtained varied between 0.435 lN/g - 0.300 l/g and 0.251 lNCH4/goS - 0.165lNCH4/goS, respectively at mesophilic temperature. The biogas produced by cow slurry was found to have an average methane (CH4) content of 58%. It was concluded that organic loading rate has a decreasing effect on the biogas and methane yields in a continuously tank reactor experiment at mesophilic temperature. The kinetic model developed could be used for dimensioning CSTR digesting organic wastes.

Open Access Original Research Article

Non-destructive Evaluation of Self-consolidating High-strength Concrete Incorporating Palm Oil Fuel Ash

M. A. Salam, Md. Safiuddin, M. Z. Jumaat

Current Journal of Applied Science and Technology, Page 1-13
DOI: 10.9734/BJAST/2015/19991

This paper presents the results of the key non-destructive tests performed on the self-consolidating high-strength concrete (SCHSC) mixes including palm oil fuel ash (POFA) as a pozzolanic supplementary cementing material. Twenty (20) SCHSC mixes were produced with several water-to-binder (W/B) ratios ranging from 0.25 to 0.40. POFA was incorporated in concrete mixes substituting 0%, 10%, 20%, 25% and 30% of ordinary portland cement (OPC) by weight. The non-destructive tests were carried out to determine the dynamic modulus of elasticity and ultrasonic pulse velocity (UPV) of the concretes. In addition, the 28 and 56 days compressive strengths were determined to verify whether the concretes possessed high strength or not. The slump flow of the concrete mixes was also investigated to observe their self-consolidation capacity. Nevertheless, more emphasis was given to observe the effects of W/B ratio and POFA content on the selected non-destructive properties of the concretes. Moreover, the correlations of UPV and dynamic modulus of elasticity with compressive strength were determined. The concrete mixes produced had the required slump flow values (≥ 600 mm) for self-consolidating concrete. The compressive strength of all concretes satisfied the strength requirement (≥ 50 MPa) of high-strength concrete for all replacement levels of OPC. The UPV and dynamic elasticity decreased with higher W/B ratio. POFA was effective in improving the non-destructive properties of concretes up to 20% replacement of cement by weight. Hence, the optimum POFA content was 20% in the context of the present study. Furthermore, the dynamic modulus of elasticity and UPV were strongly correlated with the compressive strength of SCHSC possessing a correlation coefficient of +0.9413 and +0.9709, respectively.

Open Access Original Research Article

Can Polishing Systems Restore the Smoothness of Glazed Ceramics?

Nathalie Müller Machado, Diego Fabris Ferreira da Silva, Gilberto Antonio Borges, Ana Maria Spohr

Current Journal of Applied Science and Technology, Page 1-6
DOI: 10.9734/BJAST/2015/20589

Aim: The purpose of this study was to analyze the surface roughness of three mechanically polished feldspathic ceramics by using two different polishing systems after simulated occlusal adjustment.

Methodology: Thirty feldspathic ceramic discs were fabricated: 10 with Duceram, 10 with Duceragold, and 10 with Symbio Ceram. All specimens were glazed, and 8 specimens in each group received simulated occlusal adjustment with diamond burs. Half of the 8 specimens was polished using the Edenta system, and the other half was polished using the Komet system. The mean surface roughness was measured before and after surface polishing using the Rugosimeter SL-201. Qualitative analysis of the ceramic surfaces was performed by scanning electron microscopy (SEM) in two glazed specimens and in two polished specimens. The data were submitted to analysis of variance for repeated measures, followed by Tukey's test (α=0.05).

Results: The Edenta system produced statistically lower surface roughness than the Komet system for the Duceram and Duceragold ceramics (p<0.05). However, for the Symbio Ceram ceramic, there was no significant difference between the Edenta and Komet systems (p>0.05). The application of diamond paste significantly decreased the roughness of the ceramic surface compared with the isolated application of the Komet or Edenta system. The SEM images showed that the mechanical polishing did not restore the surface smoothness of the glazed surfaces.

Conclusions: Neither the Edenta nor Komet systems reproduced the surface smoothness of glazed ceramics. The use of diamond paste considerably reduced the surface roughness. The Edenta system provided lower surface roughness than the Komet system.

Open Access Original Research Article

Phase Developments during Natural Evaporation Simulation of Lake Katwe Brine Based on Pitzer’s Model

John Baptist Kirabira, Hillary Kasedde, Matthäus U. Bäbler, Thomas Makumbi

Current Journal of Applied Science and Technology, Page 1-7
DOI: 10.9734/BJAST/2015/20598

Lake Katwe is the largest of the eight saline crater lakes in the pleistocene Katwe-Kikorongo volcanic field situated in the western arm of the great East African Rift system in southwestern Uganda. The salt lake is hydro-chemically of a carbonate type with its brines representing an important source of mineral salts of high economic value. In the present work, the geochemical simulation of the crystallization route of the natural evaporation of the lake brine in PHREEQC based on Pitzer’s thermodynamic model was done. The precipitation sequence of the different mineral salts that crystallized step by step from the brine during natural evaporation at 30ºC was obtained. The results show that the mineral salt precipitation sequence following the saturation data is: Sulfates, chlorides and carbonates. During the evaporative concentration process, the brines become enriched in Na+, K+, HCO3+ CO32-, and depleted in Cl- and SO42- with massive halite precipitation. The study provides the basis for the future comprehensive utilization of the natural brine resource in Lake Katwe.

Open Access Original Research Article

Corrosion Behaviour of Copper in LiBr Solutions: Effect of Temperature

A. E. El Meleigy, Sh. E. Abd Elhamid, A. A. El Warraky

Current Journal of Applied Science and Technology, Page 1-18
DOI: 10.9734/BJAST/2015/20045

The temperature effect of 25, 50, 70 and 80ºC on the dissolution of copper in different concentrations of Lithium Bromide (LiBr) from 3x10-2 to 9M was investigated. Three types of corrosion have been detected: General dissolution due to the formation of soluble complex of CuBr2- between the two anodic peaks (P1 and P2) of the first and second electro-oxidation process; pitting corrosion which occurs after the formation of P2 and the second type of general corrosion form due to autocatalytic dissolution of Cu+. A new type of pitting corrosion known as metastable pitting which depends on temperature and concentration has been detected.

Open Access Original Research Article

Comparative Nutritional and Phytochemical Evaluation of the Aerial and Underground Tubers of Air Potato (Dioscorea bulbifera) Available in Abakaliki, Ebonyi State, Nigeria

A. Afiukwa Celestine, O. Igwe David

Current Journal of Applied Science and Technology, Page 1-7
DOI: 10.9734/BJAST/2015/20249

The wild yam species (Dioscorea bulbifera), known as edu in Abakaliki, Ebonyi State, Nigeria, has two types of edible tubers (underground tubers and aerial bulbils) produced by the same plant. The yam species is highly neglected in the region and all over the world such that it is only consumed in the rural areas of the region often not out of preference but at periods of food scarcity. Both tuber forms are consumed in Abakaliki. The objective of this study was to evaluate and compare the nutritional and antinutritional profiles of the two tuber forms. The proximate and phytochemical constituents were determined using standard official methods of the Association of Analytical Chemists while mineral elements were quantified by Atomic Absorption Spectrophotometry (AAS) method. The study revealed no significant difference between the tuber forms in their contents of crude fats, fibre ash and carbohydrates and calorific values (P>0.05) while crude protein was significantly higher in the aerial bulbils (P<0.05). The mineral elements K, Na, Ca, Mg, Fe, Zn, Cu and P but Mn were all significantly higher in the underground tubers while the heavy metals Cd, Pb, Cr, Ni, Se and Co were not detected. Oxalate, tannins and phenols were significantly higher in the underground tubers while the bulbils were richer in alkaloids, HCN saponins and flavonoids. Compared with nutritional values of common edible yam species in the literature, this study also showed that this neglected yam species is a good source of protein, lipid, crude fibre, carbohydrates and minerals. Its contents of the toxic substances (phytate, oxalate, tannins, alkaloids and HCN) were not exceedingly higher compared to common yams. Considering the levels of proximate, minerals and phytochemicals and also the various literature reports on the medicinal potentials of D. bublifera, we advocate for increased utilization of this yam species in the area and beyond to reduce food crisis.

Open Access Original Research Article

The Use of Cubic Bezier Interpolation, Biorthogonal Wavelet and Quadtree Coding to Compress Color Images

Shaymaa D. Ahmed, Loay E. George, N. Dhannoon

Current Journal of Applied Science and Technology, Page 1-11
DOI: 10.9734/BJAST/2015/20480

In this paper, an efficient method for compressing color image is presented. It allows progressive transmission and zooming of the image without need to extra storage. The proposed method is going to be accomplished using cubic Bezier surface (CBI) representation on wide area of images in order to prune the image component that shows large scale variation. Then, the produced cubic Bezier surface is subtracted from the image signal to get the residue component. Then, bi-orthogonal wavelet transform is applied to decompose the residue component. Both scalar quantization and quad tree coding steps are applied on the produced wavelet sub bands. Finally, adaptive shift coding is applied to handle the remaining statistical redundancy and attain efficient compression performance.

The results of conducted tests indicated the developed compression system shows outstanding compression performance. The compression ratio is increased with the increase of wavelet's passes and with decrease of block size.

Open Access Original Research Article

Effects of Fabric Pattern on the Mechanical Properties of Cotton Fabric/Unsaturated Polyester Composites

E. O. Achukwu, B. M. Dauda, U. S. Ishiaku

Current Journal of Applied Science and Technology, Page 1-11
DOI: 10.9734/BJAST/2015/20006

Aims: To study the effects of fabric patterns on the properties of cotton fabric/unsaturated polyester composites made from coarse plied yarns.

Place and Duration of Study: Department of Textile Science and Technology, Ahmadu Bello University, Zaria, Nigeria, between January to December, 2014.

Methodology: Four different coarse yarns of known count were plied to obtain a single strand which was woven (plain and twill) and knitted into fabrics of different patterns. The fabrics were coated with unsaturated polyester resin as matrix, applying both single and two layers of fabrics to form laminate configurations using hand layup. The tensile properties of the fabrics, tensile properties, flexural properties, impact strength and hardness of the textile composites were studied.

Results: The plying and fabrication conferred significant reinforcement on the composites for the different mechanical properties tested. The tensile strengths of the plain, twill and knitted fabrics were 13.67MPa, 13.14MPa and 4.55MPa respectively. The knitted fabric recorded the highest breaking elongation of 82.1%. The tensile and flexural strengths of the composites were improved by 75-81% with respect to the neat polyester resin. Composites with twill fabrics gave the best tensile and flexural strengths of 18.5MPa and 62.32MPa with flexural modulus of 4.43GPa, closely followed by plain (3.35GPa) and knitted (3.23GPa) fabric composites. The impact test showed that the knitted composites absorbed more energy than the twill and plain fabric composites in that order. Increase in fabric layers also led to increases in the mechanical properties tested, but the increases were not geometrical. SEM images showed that the morphologies of the fractured surfaces were in line with the yarn orientations in the fabric cross-section with reduced fiber pull out.

Conclusion: It’s concluded that cotton fabrics made from coarse plied yarns can be used as reinforcements in textile composites.

Open Access Review Article

Phospholipid Transfer Proteins and their Regulatory Role in Lipid Metabolism and Potential Biological Functions

Manoj G. Tyagi

Current Journal of Applied Science and Technology, Page 1-8
DOI: 10.9734/BJAST/2015/20124

The phospholipid transfer protein (PLTP) is a lipid transfer glycoprotein that binds to and transfers a number of amphipathic compounds. In previous studies, the focus of the scientific community was on the specific role of PLTP in high-density lipoprotein (HDL) metabolism. Both PLTP and related cholesteryl ester transfer protein (CETP) are secreted proteins, and adipose tissue is an important contributor to the systemic pools of these two proteins. PLTP activity and its mRNA can be regulated by several factors. A diet rich in high-fat cholesterol results in a substantial increase in PLTP activity and in its mRNA levels. After a lipopolysaccharide injection, plasma PLTP activity is significantly reduced, and this is associated with a similar reduction in PLTP mRNA levels in the liver and adipose tissues. PLTP expression and activity can also be affect by glucose and insulin. This review article examines recent advances in the understanding of its potential biological roles.

Open Access Review Article

Electrodynamic Forces between Electrical Conductors and Cylindrical Magnetic Shields

Milan ` Mišić, Zorica Bogićević, Slobodan Bjelić

Current Journal of Applied Science and Technology, Page 1-11
DOI: 10.9734/BJAST/2015/20541

Aims: This paper demonstrates a method for calculating electrodynamics stress in single-phase and three-phase isolated conductors. Conductors are coated with a cylindrical shield made out of the material containing a magnetic parameter. Special emphasis is placed on induced eddy current of a shield and its effect on reduction of electrodynamics stress of three-phase conductors.

Methodology: The paper starts with the assumption that the cylindrical structure of the conductor shield is infinitely long σ=0. Inside and outside the shield applies Laplace differential equation for the magnetic vector potential [1,3]. Short circuit currents flow through the three eccentric positioned conductors and create magnetic induction or fluxes in a cylindrical shield. AC power corresponds to the time-varying resulting flux that induces eddy currents in the cylinder. Needed values of induction and fluxes relevant to eddy currents and electrodynamics forces can be determined by a method which is based on the calculation of the magnetic vector potentials and Poisson differential equation, A=µJ [2,4,5]. This procedure requires the establishment of a large number of boundary conditions and taking into account the superposition of multiphase conductive structure values. The impact measure of eddy currents in such an eccentric three-phase structure can be determined by using a similar simple procedure which one of the authors applied in the [6-17].

Conclusion: Electrodynamics forces, according to relationship (32), are significantly lower in shields which encompass only one phase of a conductor due to a protective effect of a shield. Eddy currents, as is demonstrated in this paper, significantly reduce magnetic field intensity produced by currents in conductors. Due to this effect, main electrodynamics forces in one-phase structures with shields, don`t affect the conductor but only affect the shield.