Applied Mechanics and Materials Vols. 754-755

Abstract: Copper nanoparticles, due to their interesting properties, low cost preparation and many potential applications in catalysis, cooling fluid or conductive inks, have attracted a lot of interest in recent years. In this study, copper nanoparticles were synthesized through the palm leaves extract that act as reducing agent. In this synthesis route, the hydroxyl groups of the polyphenols in palm extract are capable to act as reducing agent for reduction reaction. The effect of temperature given starting with control parameters at room temperature proceeds to 40, 50, 60, 70 and 80°C with the time length of 2 hours and 10 milimol copper nitrate aqueous solution. Characterization had been conducted using the instrument of UV-vis spectrophotometer, FTIR and ESEM. The average size of all powder nanoparticles was found to 109, 86, 196, 133, 241, and 230nm accordingly from room temperature till 80°C. The correspondence analysis of the results yielded that the optimum temperature was at 40°C which is 86nm of average copper nanoparticle size.

Abstract: . The paper present aspects about the obtaining of non-precious dental alloys (type CoCrMo and CoCrMoSi7), the determination of chemical composition by optical emission spectrometry and the experimental tests for determining the tensile strength, made on standard plate samples. The base material used in experiments was a commercial alloy, from CoCrMo system, which belongs to the class of dental non-precious alloys, intended to medical applications. The obtaining of studied alloy was made on arc re-melting installation, under vacuum, type MRF ABJ 900. The process followed to realize a rapid melting, with a maximum admissible current intensity. The samples for tests were obtained by casting in an electric arc furnace, under vacuum, in optimal conditions for melting and solidification and processing by electro-erosion, to eliminate all the disturbing factors which come by processing conditions for the samples. The determination of chemical composition for cobalt based alloys, by optical emission spectrometry, was made on SpectromaxX equipment with spark. The electrical discharge is made with the elimination of an energy quantity, fact which determine plasma forming and light issue. Tensile tests for standard samples, made from cobalt based alloy, was made on Instron 3382 testing machine, and assisted by computer. The obtained results are: elongation, elasticity modulus, tensile strength and offer complete information about the analyzed mechanical properties. For the certitude of obtained experimental results, the tests were made on samples with specific dimensions according ISO 6892-1:2009(E) standard, both for the tensile strength, and also machine operation.

Abstract: The waste from the kenaf water retting; kenaf core can be used to create by-product. The characteristics of the kenaf are important to create new by-product. Cellulosic materials can be obtained from fibrous plants which known as cellulose, hemicelluloses, lignin, waxes, and several water-soluble compounds. Kenaf was categorized as one of the fibrous family plants. Hence, its cellulosic materials need to be determined before extraction process. This research was conducted to determine the cellulosic materials concentration in kenaf core using Thermal Gravimetry Analyzer (TGA) and Differential Scanning Calorimetry (DSC). As result, the percentage of degradation and decomposition of cellulosic materials were recorded and analyzed as reported in this paper.

Abstract: In recent years, tamarind seeds extracts are used widely in food, pharmaceutical and textile industry due to unique functions as cooking oil, antibacterial and thickening agent. In this study, a simple static technique is used to obtain the solubility of tamarind seed in supercritical carbon dioxide because there is no study on that yet. The solubility measured is performed at temperatures and pressures ranging from 40^oC, 60^oC, 80^oC and 3000psi, 5000psi and 7000psi respectively; resulting in mass fractions in the 6.00 x 10^-8 to 5.84 x 10^-7 range. The Chrastil model is used to correlate the experimental data. The oil yield extract in range of 0.0375 to 0.365g.

Abstract: In this study, the ability of treated oil palm ash aided with kaolin powder to produce zeolites is studied. The use of treated oil palm ash in the zeolites conversion seems to be an option for waste materials management. Characterization of treated oil palm ash from Malaysia’s palm oil plantation has been acquitted. The treated oil palm ash and kaolin powder are used as the starting material for the synthesis of zeolites materials. The method chose for the zeolites conversion is alkaline hydrothermal treatment. The chemical composition, crystalline phases and elemental composition of treated oil palm ash and as-synthesized samples were characterized and studied. From the analysis, the treated oil palm ash was a fertile source of silica and exists as quartz phase. The outcomes have significant motivation for the production of zeolites by using low cost material such as treated oil palm ash.

Abstract: Cerbera odollam’s tree parts were extracted with methanol and further fractionated using n-hexane, ethyl acetate and ethanol, followed by antibacterial assay against Bacillus subtilis, Bacillus licheniformis, Escherichia coli and Pseudomonas aeruginosa. Hexane soluble parts from flower, fruit, leaf, wood, bark and ethyl acetate soluble part from bark showed antibacterial activity against Bacillus subtilis. Hexane soluble parts from leaf and bark and ethyl acetate soluble parts from wood showed antibacterial activity against Bacillus licheniformis. All fractions appeared ineffective on Escherichia coli and Pseudomonas aeruginosa. Screened extracts were analysed using FTIR. Experiments were continued with impregnation of methanolic extracts of Cerbera odollam into Melamine-urea formaldehyde (MUF) particleboards, Phenol-resorcinol formaldehyde (PRF) particleboards and solid wood samples followed by exposure to wood-boring beetles and natural decaying.

Abstract: Protein production by bacteria might be increased in stressful conditions such as in the presence of antimicrobial agents. Many studies proved that antibiotics or antimicrobial agents at low concentration are able to activate or repress gene transcription process in bacteria. However, there are still few studies on potential of natural antimicrobial compounds such as Cymbopogon essential oils acting as specific chemical signal that can trigger biological functions of bacteria. Therefore, this study aims to explore the potential of natural antimicrobial compound (Cymbopogon flexuosus and Cymbopogon nardus) at low concentration in regulating proteins production by Lactobacillus plantarum ATCC8014. The bacteria cells of L. plantarum ATCC8014 are exposed to Cymbopogon essential oils at low concentration in fermentation process for 48 hours at 37°C. SDS-PAGE analysis showed that a new intracellular protein with approximate size of 40 kDa was produced by L. plantarum ATCC8014 after being enhanced with C. nardus essential oil. Besides, the intracellular proteins, each with approximate size of 85 kDa, 45 kDa and 28 kDa synthesized by L. plantarum ATCC8014 prior to inducing with C. nardus or C. flexuosus were expressed differently. Some of the intracellular proteins were highly expressed and some of the proteins were repressed based on the intensity of protein bands appeared. Hence, L. plantarum ATCC8014 in the presence of Cymbopogon essential oils at low concentration could regulate the intracellular proteins production. The isolated protein also showed antimicrobial activity against selected Gram-positive and Gram-negative bacteria.

Abstract: Alkaliphilic cellulases-producer fungi were isolated from soil of limestone areas in Perlis. The potential strain was isolated by soil dilution plate method on enriched selective medium using CMC as substrate at different pH levels. Eleven isolates of different morphological colonies were screened using the hydrolysis capacity test by Gram’s iodine. Out of eleven colonies, five showed positive results as the hydrolysis zone formed. BK1 showed the highest hydrolysis capacity among all sample strains for every pH levels. Eventually, four strains were selected to be further explored as cellulolytic fungi for the production of alkaline cellulase in the future.

Abstract: A 3-dimensional hip joint implant model was constructed which separates into three individual parts namely femoral stem with neck, femoral head and acetabular cup. Each part were assigned with the specific materials and a total of 3000 N loads was applied to mimic the body weight of an adult in static position or in double leg standing position. The results of the stress distribution were obtained from the finite element analysis for the difference diameter for each component of ball-socket and neck as well as the difference materials. The results showed that an optimum diameter of femoral ball-socket with 36 mm and titanium alloy have design rigidity which provided better performance and longer life span based on 13.922 Mpa equivalent stress .

Abstract: This study was to investigate the proximate composition, total antioxidant activity and functional properties of mango (Mangifera indica L. var Perlis Sunshine) peel flour. The proximate analysis (g/100g) was determined as carbohydrate (84.6%), fat (4.0%), total protein (1.6%), total dietary fiber (54.2%), soluble dietary fiber, (SDF) (20.0%), insoluble dietary fiber, (IDF) (34.2%) and calories (381 kcal/100g). The studies also indicated that mango peel flour from Perlis Sunshine varieties can neutralized DPPH radicals by neutralized 80.00% of free radicals, thus contained about 22.4 mg/g of total flavonoids contents (TFC) values and 21.7 mg/g of total phenolic contents (TPC) values. Functional properties of between wheat flour and mango peel flour concentration were analyzed in terms of water and oil holding capacity, foaming capacity and stability, swelling capacity, emulsion activity and stability, and bulk density, respectively. The present data may provide guideline for food formulation based on Perlis Sunshine mango peel flour.