Applied Mechanics and Materials Vols. 754-755

Abstract: Magnesium alloys with their biodegradable characteristics can be a very good candidate to be used in biomedical implants. AZ91D magnesium alloy had been chosen for investigating the effect of gadolinium concentration on corrosion performance. AZ91D magnesium alloy was immersed in La (NO₃)₃, Mg (NO₃)₂, and Gd (NO₃)₃ in simulated body fluid (SBF) solution. The structure and formation mechanism of the coating are discussed in detail through surface morphology, corrosion rate and electrochemical test. The effects of gadolinium in different concentration on the corrosion performance of magnesium substrate are investigated.

Abstract: A study was conducted to determine the most optimal preservation technique for P. sajor-caju spawns which produce maximum specific growth rate and shortest doubling time by using contois kinetic model. The analyzed experimental data showed that lyophilized P. sajor-caju spawn showed the highest maximum specific growth rate, and shortest doubling time compared to cryopreserved P. sajor-caju spawn and 4oC stored P. spawn. There was no significant difference in aspect of growth rate between the lyophilization and cryopreservation techniques which were; 0.148 (μ_max)/ (g/day) and 0.147(μ_max)/ (g/day) respectively. Based on the result, lyophilization technique was considered as the best preservation technique for preserving P. sajor-caju spawn due to high maximum growth rate which indicates high survival after exposure to preservation treatment.

Abstract: Freshwater aquaculture has high production rate, but the inconsistency supply of feeds can lead to low quality of fish. This initiates a high demand of fish feeds with complete diet to assist in growth and performance of the reared fish. The conventional fish meal has high protein content but it is expensive and can lead to high manufacturing cost of fish feeds. Therefore, present study is conducted to demonstrate nutritional value in several potential ingredients for formulation of new and economically favorable fish feed formulation for catfish. Proximate analysis of earthworm powder, fish meal, leucaena leucocephala leaves, soybean waste and rice bran was performed to analyze their moisture, ash, protein and crude fiber content. While amino acid analysis was carried out to obtain amino acid profiles. Based on the results, the selected ingredients demonstrated remarkable nutritional content which are required in the catfish diet, thus indicate their high potential as substitute ingredients in fish feed formulation.

Abstract: Computing alignment matrix score to search for regions of homology between biological sequences is time consuming task. This is due to the recursive nature of the dynamic programming-based algorithms such as the Smith-Waterman and the Needleman-Wunsch algorithmns. Typical FPGA-based protein sequencer comprises of two main logic blocks. One for computing alignment scores i.e. the processing element (PE), while another logic block for configuring the PE with coefficients. During alignment matrix computation, the logic block for configuring the PE are left unused until the time consuming alignment matrix computation finished. Therefore, a new technique, known as overlap computation and configuration (OCC) is proposed to minimize the time overhead for performing biological sequence alignment. The OCC technique simultaneously updating substitution matrix in a processing element (PE) systolic array, while computing alignment matrix scores. Results showed that, the sequencer achieves more than two order of magnitude speed-up higher compared to the state of the art, at negligible area overhead, if any.

Abstract: Magnesium (Mg) alloy possess a high demand in biomedical applications due to their biocompatibility and biodegradability. However the main limitation for Mg alloy is their fast degradation rates in physiological environment. This paper reports the preparation of porous Mg alloy through powder metallurgy technique by using ammonium bicarbonate (NH₄HCO₃) as space holder material and hexane as solvent. The corrosion behavior and degradation rate of porous Mg alloy was measured after 24h, 96h and 168h respectively of immersion in simulated body fluid (SBF) with compact Mg alloy as control. The results reported that degradation rate increased with increasing immersion period, yet the compact Mg alloy shows better degradation rate than porous Mg alloy. Moreover, the pH of SBF changed proportional to immersion period and stabilized after 96h of immersion.

Abstract: Nanoemuslion is type of dispersion of emulsion in nanoscale from the effect that forms by shear that inducing rupturing. This small particle size of distribution conduit a higher efficiency in the sweeping trapped oil and lowering the IFT as the small size of nanoparticle provided a larger surface area contact to the reservoir. Thus, nanoemulsion is one of the new implemented techniques of the nanotechnology formulation of chemical flooding in the oil and gas industry. This paper presented the formulation of nanoemulsion using biodegradable oil as the nanoemulsion is the oil in water emulsion. Biodegradable oil is proven able to introduce a several advantages in the industry as it is renewable, environmental friendly, and produced easily in rural areas. In this research, nanoemulsion was formulated using three chosen biodegradable oil which is a corn oil, olive oil and sunflower oil that had been emulsified in the non ionic surfactant (Tween 80) and distilled water. The nanoemulsion that had been formulated was being analyzed based on particle size of distribution. Water flooding oil recovery using the lowest salinity of brine had recovered at average of 50% of IOIP. In the nanoemulsion flooding in enhance oil recover; corn oil has the recovered the highest percentage of IOIP which is 34.38% followed with olive oil 32.79% and sunflower oil 30.23%. Corn oil nanoemulsion is the most optimum biodegradable oil to be act to be act as displacing fluid in EOR chemical flooding in this case of research paper.

Abstract: Extraction of oil from Jatropha curcas L. seed and kernel using hexane as solvent was performed at supercritical state of hexane; temperature from 200-280 °C, pressure from 4-12 MPa, with fixed 30 min extraction time, sample ratio to solvent 1:40 (w/v), and 300 rpm in a 1-liter high-temperature high-pressure batch wise reactor system. The percentages of oil yield from seed and kernel obtained via supercritical hexane were 67.2 and 81.2 %, respectively. The percentages of oil yield increase with increasing in pressure and temperature. The percentages of oil yield via supercritical hexane extraction were much better compared to soxhlet extraction (i.e. seed, 37 % and kernel, 48 %) and mechanical pressing techniques (i.e. seed, 30 % and kernel, 25 %). Oils extracted were derivatized into FAMEs before quantified using GC-MS. The results showed that maximum oil yield was obtained at temperature 280 °C, pressure 12 MPa, whereby oleic acid is the most abundance (43.4 %) followed by linoleic acid (29 %), palmitic acid (20.1 %) and stearic acid (7.5 %). Comparison extraction with soxhlet and mechanical pressing showed that the percentages of FAMEs distributions are similar in all extracts and they agree with the previous data obtained by other researchers.

Abstract: The aim of this study was to optimize the monoepoxidation process of linoleic acid obtained from Malaysian Jatropha curcas oil using central composite design (CCD). There were four independent variable factors had been studied which involved reaction temperature (X₁), reaction time (X₂), catalyst loading (X₃) and H₂O₂ concentration (X₄). Thirty experiments were carried out based on the experimental design responses obtained. The results showed that the optimum condition was obtained at catalyst loading of 0.11% (w/w) methyltrioxorhernium (VII) (MTO), H₂O₂ mole of 99%, reaction temperature of 58.41^oC for 5 hours. The central composite design was proven to be simpler method, time saving and required less samples compared to the conventional method.

Abstract: Cu₂Zn_0.8Cd_0.2SnS₄ pentrary alloy nanostructure were prepared and deposited on glass substrates with different copper concentrations ( 0.3, 0.5, 0.7 and 0.9 mol/L ) using Sol gel – spin coating method.morphological and analytical studies were investigated by Field Emission-Scanning Electron Microscope (FE-SEM), atomic force microscopy (AFM). It is found that the average grain size of Cu₂Zn_0.8Cd_0.2SnS₄ pentrary alloy nanostructure is 51.92 to 76.43 nm for the thin films prepared at 0.3, 0.5, 0.7 and 0.9 mol/L respectively .

Abstract: Optimization gap size and integration of TiO₂ nanoparticles thin film produce a sensitive sensor device. Sol-gel spin coated TiO₂ nanoparticles thin film is coated on a conventional fabricated IDEs with gap sizes of 7 μm, 10 μm, 14 μm and 17 μm which is then validated through electrical characterization. I-V characteristics of without and with TiO₂ thin film of various gap sizes are subjected to pH test are then plotted to describe the resistance of the devices and correlate with the sensitivity measurement. Sensing devices show that devices with larger spacing and greater pH values have higher current. On the other hand, integration of TiO₂ thin film reduced the resistance of devices. Among the four gap sizes, 7 μm gap sized device is the most sensitive one due to the tremendous difference after small amount of pH dropped on surface, thus lowering the detection limit.