Forthcoming Issue

 

Vol. 28, No. 3 (November 2017):

1. Numerical Analysis of Dielectric Heating in Cancerous Liver Tissue, by A.A. Abdelmalik, S.G. Nnamdi, I.H. Zubairu

Abstract: Percutaneous energy-based ablation has been used for the treatment of many tumour types. The advent of thermoablative technology for the treatment of small size liver tumour introduced several advantages over surgical resection. The technology involves the creation of an electromagnetic field through an intratumourally placed antenna. A process known as dielectric heating elevates the temperature of the tissue immediately surrounding the slot of the antenna where most of the coagulative necrosis occurs. Attenuation of the electromagnetic field as it travels through the tissue leads to decrease in the rate of tissue necrosis creating a zone of sub-lethal hyperthermia, and then a zone of tissue unaffected by ablation. The temperature spreads across the tissue to destroy the cancer cells. This occurs both directly and indirectly at the membrane and sub cellular levels. Several mechanisms including mitochondrial dysfunction, changes in cell membrane integrity and inhibition of DNA replication have been postulated as pathways through which cell death following hyperthermia occurs. The absorption of power by the tissue (SAR) and the destruction of cancer cell is highly dependent on time and the input power of the antenna. This paper presents the numerical analysis of the important parameters in microwave thermotherapy and the biological mechanisms involved in the death of tumour cells.

2. Tailoring the Chemical and Structural Properties of Graphene Oxide Nanoplatelets Synthesised at Room Temperature with Different Processing Times, by Toh Guat Yee et al.

Abstract: A simplified Hummer’s method was successfully used in synthesising graphene oxide nanoplatelets. These nanoplatelets were synthesised at room temperature at various processing times (24 hours, 72 hours, and 120 hours). Ultraviolet visible spectroscopy (UV-vis) showed that all synthesised graphene oxide nanoplatelets suspensions have similar broad shoulder absorbance at a wavelength of 300 nm. Furthermore, similar functional groups were detected by Fourier transform infrared spectroscopy (FTIR) across all types of graphene oxide nanoplatelets structures. The effect of processing time on the thickness of the sheet size was interpreted through topology using atomic force microscopy (AFM). The structural properties of graphene oxide nanoplatelets were evaluated using X-ray diffraction (XRD). The results showed a slight increase in the interlayer spacing with no sharp distinction in the crystallinity for graphene oxide nanoplatelets at longer processing times. The ratio of carbon to oxygen composition on the surface of each synthesised graphene oxide nanoplatelet was computed using the X-ray photoelectron spectroscopy (XPS). Field emission scanning electron microscopy (FESEM) was used to determine the morphology of the nanoplatelets. Three steps of degradation occurred during the thermogravimetric analysis (TGA). Degradation peaks were identified using differential scanning calorimetry (DSC). Electrical properties were characterised using the four-probe conductivity method. It can be concluded that properties such as sheet size, thickness, morphology and electrical conductivity of the graphene oxide nanoplatelets can be tuned by varying the processing time while maintaining its chemical characteristics.

3. Comparison Between Use of Lysol and Effective Microorganism to Manage Odour at Municipal Waste Transfer Station, by Nastaein Qamaruz Zaman et al.

Abstract: Ampang Jajar Transfer Station (AJTS) in Pulau Pinang, Malaysia receives wastes from North and Central Seberang Perai, which are consolidated at AJTS before final disposal at Pulau Burung Sanitary Landfill located 40 km south. AJTS is located in an industrial area with the closest residences, Flat Ampang Jajar, about 300 m away. Efforts have been in place to manage odour nuisance by spraying solutions of Effective Microorganism (EM) and Lysol at the operation area of the AJTS. This study was conducted with the objective of verifying the effectiveness of EM and Lysol in odour control and their suitable spraying frequency. Solid wastes taken from AJTS were characterised in the laboratory for solids and moisture content, while its leachate was analysed for COD and volatile fatty acids. A portion of the collected sample was also tested for odour concentration with and without EM and Lysol application. Laboratory analysis indicated that AJTS waste is highly degradable with 72% moisture content and 76% volatile solids, thus susceptible to odour production during decomposition. Acetic, butyric and propionic acid were present at concentrations of 3618 ppm, 581 ppm and 549 ppm respectively, higher than their respective odour threshold detection value of 0.21 ppm, 0.001 ppm and 0.16 ppm. The sour and rancid smell attributed with the waste sample is contributed partly by the VFA content. AJTS sample in laboratory conditions was treated more effectively by Lysol (57% odour reduction) compared to EM (24% odour reduction). Lysol reduces malodour by masking the unpleasant ‘sour garbage’ odour with a ‘soapy’ scent instead, leading to a perceived ‘mildly unpleasant’ (-1) hedonic tone. The current spraying of Lysol twice every 6 hour at the AJTS is sufficient to manage odour to acceptable levels for seven hours after spray.

4. Biodegradation of Phenol by Unacclimated and Phenol-acclimated Activated Sludge: Effects of Operational Factors on Biodegradation Efficiency and Kinetics, by Sam Suat Peng and Ng Si Ling

Abstract: This study was conducted to investigate the effects of operational factors, namely: 1. type of activated sludge; 2. activated sludge concentration; 3. initial phenol concentration; and 4. addition of sucrose, on the biodegradation of phenol in batch experiments. At various initial phenol concentrations, complete phenol biodegradations with chemical oxygen demand (COD) removal of 95% were achieved by both unacclimated and phenol-acclimated activated sludge. The performance of biodegradation was greatly enhanced, with biodegradation time shorten from 330-1260 to 35-330 min for initial phenol concentrations of 25-250 mg l-1, when the activated sludge was acclimated to the target compound, despite the low acclimation concentration of 50 mg l-1. Phenol biodegradation time was found to decrease with increasing activated sludge concentration and decreasing initial phenol concentration. In the presence of sucrose as co-substrate, biodegradations of phenol by both unacclimated and phenol-acclimated activated sludge were improved. The kinetic data for the biodegradation of phenol was well-fitted into pseudo-first-order model. The values of rate constant of phenol-acclimated activated sludge were found to be higher compared to those of unacclimated activated sludge under all the operational conditions studied. For phenol-acclimated activated sludge, the values of pseudo-first-order rate constant, k, were observed to decrease with increasing concentration of activated sludge and decreasing initial phenol concentration.

5. Comparison of High Pressure-Induced Phases of Mg(AlH4)2 as Hydrogen Storage Using Ab Initio Calculated NQCC Parameters, by Marjan A. Rafiee

Abstract: Nuclear quadrupole resonance (NQR) spectroscopy is a very sensitive technique for measurement of the electric charge distribution around quadrupolar nuclei. Quadrupolar parameters of nuclei can be used as a tool to understand the electronic structure of compounds. The electronic structure of Magnesium alanate, Mg(AlH4)2, as promising hydrogen storage materials for hydrogen fuel cell powered automobile applications, has been studied in detail by ab initio calculated NQR parameters. Furthermore, using calculated nuclear quadrupole coupling constants (NQCCs) of hydrogen atoms (2H-NQCC), the electronic structure of a-Mg(AlH4)2 with its high-pressure forms, ß- and ?- Mg(AlH4)2, was compared. The electric field gradient (EFG) at the site of 2H atoms was calculated to obtain NQCC parameters. The results show that in the ?-Mg(AlH4)2, 2H-NQCCs are smaller than that of other considered phases. In other words, Al–H bonds in ?-Mg(AlH4)2 nanocrystal is weaker than others and the charge transfer from Al to hydrogen atom is less than the others and therefore these hydrogens have weaker bonds with Al and easier condition for dehydrogenation is expected in ?-Mg(AlH4)2. Comparison of calculated dehydrogenation enthalpies of various Mg(AlH4)2 phases verifies this prediction. All calculations performed using Gaussian 03 at the HF/3-21G level of theory. The selected level and basis set give the rather acceptable qualitative NQCCs of hydrogen atoms.

6. Application of Low Cost Natural Rubber Films for Water Remediation, by N. H. Hasanuddin et al.

Abstract: Pristine natural rubber (NR) and its composites including natural rubber-halloysite nanotube (NR-HNT) as well as natural rubber-silver (NR-Ag) have been prepared in the form of films for the decolorisation of dyes via adsorption as well as degradation. As an adsorbent, the flatsheet NR film was capable in adsorbing methylene blue (MB). However, incorporation of HNT into the films enhanced this property. It was found that the percentage of MB removal increased from 66 % to 93 % within 2 hours when 10 wt % and 70 wt % HNT was incorporated respectively. The NR film was also able to function as a catalytic film in the presence of Ag. The flatsheet NR-Ag films degraded MB with Ag content of as low as 0.002 wt%. Furthermore, we show that the efficiency of these films can be improved by preparing porous NR films. This work shows how the function of NR can be altered by incorporating various fillers.

7. Degradation of the Antibiotic Ceftriaxone by Fenton Oxidation Process and Compound Analysis, by Hastheesudabye Puddo, Rajesh Nithyanandam and Thaothy Nguyenhuynh

Abstract: Fenton oxidation process is used to degrade the recalcitrant pharmaceutical product ceftriaxone (CF), a commonly-used antibiotic in Malaysia. An effluent containing ceftriaxone antibiotic whose chemical oxygen demand (COD) and total suspended solids (TSS) was found to be 944 mg/l and 280 mg/l respectively. Physical and chemical treatment methods were employed to find the optimal concentration of Fenton reagent which was needed to degrade the antibiotic to a safe disposal level. Physical treatment included the variation in temperatures (37°C, 42°C, 47°C and 50°C) and pH (2.6, 5.2, 6.1 and 10). The molar concentration of Fenton reagent was varied from 0.1M, 0.2M, 0.3M, 0.35M to 0.4M. The molar ratio of ferrous ions (Fe2+) to hydrogen peroxide ions (H2O2) in Fenton reagent was varied between 1:2, 1:4, 1:8 and 1:10. The optimum conditions for maximum reduction in COD level were at pH 2.6, 0.4M of Fenton reagent and Fe2+/H2O2 ratio of 1:8, reaching 84.6% reduction within 30 minutes of reaction. The experiment was carried out at ambient temperature 28°C and at atmospheric pressure. A further investigation (pH and temperature variation) was made to deduce the percentage of reduction in terms of COD and TSS level that were obtained by the optimum sample. Findings reveal that a significant decrease of 76.5% was observed at 47°C and pH 5.2. Total suspended solid investigation reveals that a maximum reduction of 93% occurred at 0.4 M of Fenton reagent having the ratio of Fe2+/H2O2 of 1:2. Furthermore, 8 intermediates (5-Thiazolecarboxylic acid, 5-[5-(Methoxymethyl)-1,2-oxazol-3-yl]-4H-1,2,4-triazole-3,4-diamine, Methanone bis [(methylthio)oxidoamino], 5-{[2,6-Dimethyl-4-(2-methyl-2-propanyl)benzyl]sulfonyl}-1-pentanol, Benzene 5-(1,1-dimethylethyl)-2-[[(2-ethoxyethyl)sulfonyl]methyl]-1,3-dimethyl, 3D 1-(Ethylsulfonyl)-5-methoxy-6,6-dimethyl-4-heptanol, 3-{[2,6-Dimethyl-4-(2-methyl-2-propanyl)benzyl]sulfonyl}-1-propanol and 2R-3-[(S)-{(1R)-1-[4-(2-Methyl-2-propanyl)phenyl]ethyl}sulfinyl]-1,2-propanediol were identified from the degradation products obtained by LC/MS analysis.

8. Physical, Mechanical and Thermal Properties of Sugar Palm Yarn Fibre Loading on Reinforced Unsaturated Polyester Composites, by N. Mohd Nurazzi et al.

Abstract: This study was conducted to evaluate the performance of sugar palm yarn fibre reinforced unsaturated polyester composites. The effect of sugar palm fibre yarn loading on the physical (density, voids and water absorption analysis), mechanical (tensile, flexural and impact analysis) and thermal (TGA) properties of composites were investigated. Composites with different sugar palm fibre yarn loadings (10, 20, 30, 40 and 50 wt.%) were prepared using the hand layup method. Results showed that the determination of composite density indicates void determination, much of which is related to an increase in fibre loadings. Determination of water absorption at various loadings revealed that the percentage of water absorption increases as fibre loading increases. Water absorption reached equilibrium absorption at day 12. Tensile strength, tensile modulus, flexural strength and flexural modulus show increments up to 30 wt.% of fibre loadings. Elongation at break showed an increasing trend up to 50 wt.% of fibre loading. Furthermore, impact strength of the 40 wt.% fibre loadings sample showed the highest impact energy in resisting the fractures among all samples. The addition of sugar palm decreases the thermal stability of the entire system.

9. Effect of Cement Factory Exhaust on Radiological Contents of Surrounding Soil Samples in Assuit Province, Egypt, by El-Taher et al.

Abstract: In the present work, the natural radioactivity of surrounding soil samples collected from Assuit cement factory (Egypt) have been measured by using NaI(Tl) detector. Gamma analysis for each sample along with the calculated specific activities shows that the average concentrations of Ra-226, Th-232 and K-40 were 31.44 ± 3.67 Bq/kg, 39.77 ± 2.00 Bq/kg and 113.23 ± 5.66 Bq/kg respectively, where only the values of Ra-226 and K-40 are lower than the worldwide average, while the average value of radium equivalent activity, absorbed gamma dose rate, external and internal hazard indices, gamma index, alpha index, indoor and outer door effective doses for each sample were 132.02 Bq/kg, 43.27 nGy/h, 0.256, 0.346, 0.691, 0.157, 0.212 mSv/y and 0.0572 mSv/y respectively. All these values were found to be lower than the permissibility limit value.

10. Properties of Binderless Particleboard and Particleboard with Addition of Urea Formaldehyde Made from Oil Palm Trunk Waste, by Mohana Baskaran et al.

Abstract: Malaysia produces a large amount of oil palm biomass yearly especially in the form oil palm trunks. The purpose of this research was to convert oil palm trunk waste into value-added panels namely particleboard. Binderless particleboards and particleboards with addition of 10% urea formaldehyde were made from oil palm trunk particles at higher thickness levels. Particleboards were manufactured at two thickness levels namely 10 mm and 15 mm at target density of 0.8 g/cm3. Physical and mechanical properties of particleboards including density, thickness swelling, water absorption, modulus of rupture and internal bond strength were determined. Moreover, properties of oil palm trunk particleboard were characterized in term of thermal analysis by thermogravimetric analyses (TGA) and morphological analysis by scanning electron microscopy (SEM). Based on the results obtained, particleboards with addition of urea formaldehyde exhibited higher physical and mechanical properties in comparison to binderless particleboards at each thickness levels. On the other hand, particleboard of 10 mm in thickness showed better properties than particleboards of 15 mm in thickness except for modulus of rupture. The mechanical properties of all types of boards have met the minimum requirement of Japanese Industrial Standard for Type 8. The overall results revealed that addition of minimal amount of urea formaldehyde as adhesive can improve the basic properties of oil palm trunk particleboard.