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Hindatu Y.,University of MalayaKuala Lumpur | Hindatu Y.,Bauchi State University | Annuar M.S.M.,University of MalayaKuala Lumpur | Gumel A.M.,University of Nigeria
Renewable and Sustainable Energy Reviews | Year: 2017

Microbial fuel cell (MFC) harnesses the metabolic activities of microorganism to generate electricity from substrate oxidation. However, the power generated from the MFC is relatively low for practical applications, thus the urgent need for its improvement. In MFC, anode is a crucial component of the setup, both structurally and functionally. It provides support for bacterial attachment and simultaneously acts as a sink for electrons from substrate metabolism. Poor performance of anode electrode in MFC is still a major setback for its practical applications. Successful anode electrode modification is expected to enhance the MFC electricity generation efficiency. Materials such as carbon nanotube, stainless steel, conducting polymers, metal oxides, and electrolytes have been employed as anode electrode modifiers with varying degree of success. Henceforth, this communication highlights and discusses the latest research advances made in MFC anode electrode modification using the aforementioned materials. The importance of the modification methods and their consequences towards anode architecture, biocompatibility, and longevity to improve the overall MFC performance are discussed. © 2017 Elsevier Ltd

Ahmed T.,University of MalayaKuala Lumpur | Mekhilef S.,University of MalayaKuala Lumpur | Shah R.,University of Manchester | Mithulananthan N.,Queensland University of Technology
Energy Policy | Year: 2017

This work is a feasibility study of high voltage AC (HVAC) and high voltage DC (HVDC) transmission option for the Association of Southeast Asian Nations (ASEAN) Power Grid (APG) interconnections. An optimal power flow, a minimum-cost power generation model, is developed in the MATPOWER simulation platform to perform this analysis. Electricity generation and consumption data are taken from the latest power development plans of individual ASEAN countries for the evaluation of optimal cross-border power flow through the interconnections. Results show that APG can enhance power generation from countries with abundant renewable resources to meet the growing demand at load centers in the ASEAN member nations. An annual cost is used as the output matrix for this study. The analysis results reveal that in some interconnections, implementing HVDC link instead of currently planned HVAC could be economically beneficial for the APG. The findings in this paper would serve as valuable references for the APG planners. © 2017 Elsevier Ltd

Go Y.-H.,University Tunku Abdul Rahman | Lau W.-Y.,University of MalayaKuala Lumpur
Resources Policy | Year: 2017

This study examines the hypothesis of Tilton et al. (2011) that assert investor demand affects commodity prices when spot and futures prices are closely correlated during strong contango in a hard commodity like copper. However, using daily data of crude palm oil (CPO) spot and futures prices from January 2000 to July 2016, after taking into account the variance of the increments in a random walk as measured by variance ratio, our study finds that spot and futures prices are highly correlated during backwardation period. It is further observed that: First, investor demand on the futures market is highly correlated with spot and futures prices during backwardation, but lesser during weak contango, and the least correlated during strong contango. Second, the efficiency of the futures market is related to the degree of correlation between spot and futures price changes. High efficient information transmission in the futures market is linked to a high correlation between spot and futures markets and vice versa. Therefore, we extend the hypothesis that the preference of holding a long position in the futures market is due to the anticipation of insufficient supply of CPO which happens during the backwardation period. © 2017 Elsevier Ltd

Al-Obaidi K.M.,University of MalayaKuala Lumpur | Azzam Ismail M.,University of MalayaKuala Lumpur | Hussein H.,Royal University | Abdul Rahman A.M.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2017

This paper provides an overview of the design of biomimetic building skins. Many types of smart and responsive building envelopes have been developed, but their improvement to achieve adaptability remains unclear and unstructured. Studies on biomimicry have formulated strategies but have failed to identify or review their technical and functional aspects in terms of architecture. Therefore, this study aims to understand biomimetic building skin designs by investigating its mechanisms, functions and materials through an adaptive approach. This study describes these biomimetic designs through theories, concepts, issues, approaches, methodologies, materials from nature, developed materials and systems in architectural applications. The study also employs a systematic quantitative research to enhance the integration of biology and architecture. This research is based on an evidence review focusing on selected studies and exploration results in accordance with systematic methods and critical analyses, such as classification and comparison, to identify patterns and trends. This study provides further insights into the relationship between biological systems and building skins. It also contributes to the development of adaptive building skins based on functional aspects to overcome technical challenges and promote innovation and sustainable architectural systems. © 2017 Elsevier Ltd

Khalit W.N.A.W.,University of MalayaKuala Lumpur | Tay K.S.,University of MalayaKuala Lumpur
Ecotoxicology and Environmental Safety | Year: 2017

Unmetabolized pharmaceuticals often enter the water treatment plants and exposed to various treatment processes. Among these water treatment processes, disinfection is a process which involves the application of chemical oxidation to remove pathogen. Untreated pharmaceuticals from primary and secondary treatment have the potential to be exposed to the chemical oxidation process during disinfection. This study investigated the kinetics and mechanism of the degradation of sotalol during chlorination process. Chlorination with hypochlorous acid (HOCl) as main reactive oxidant has been known as one of the most commonly used disinfection methods. The second order rate constant for the reaction between sotalol and free available chlorine (FAC) was found to decrease from 60.1 to 39.1 M−1min−1 when the pH was increased from 6 to 8. This result was mainly attributed by the decreased of HOCl concentration with increasing pH. In the real water samples, the presence of the higher amount of organic content was found to reduce the efficiency of chlorination in the removal of sotalol. This result showed that sotalol competes with natural organic matter to react with HOCl during chlorination. After 24 h of FAC exposure, sotalol was found to produce three stable transformation by-products. These by-products are mainly chlorinated compounds. According to the acute and chronic toxicity calculated using ECOSAR computer program, the transformation by-products are more harmful than sotalol. © 2017 Elsevier Inc.

Ashik U.P.M.,University of MalayaKuala Lumpur | Wan Daud W.M.A.,University of MalayaKuala Lumpur
RSC Advances | Year: 2015

n-Ni/SiO2, n-Fe/SiO2 and n-Co/SiO2 nano-catalysts were prepared by co-precipitation cum modified Stöber method and applied for thermocatalytic decomposition of methane in order to investigate their thermal stability and activity to produce greenhouse gas free hydrogen and nano-carbon. The mean particles sizes of the produced nano-catalysts obtained from BET analysis are 32.19 nm, 30.26 nm and 49.92 nm, respectively. Temperature programmed methane decomposition were conducted as a preliminary catalytic examination and further isothermal analyses were performed at 700 °C, 600 °C and 500 °C. Production of hydrogen at each experimental temperatures and corresponding carbon yield were measured. Among the three catalysts inspected, n-Ni/SiO2 was found to be the most efficient one for thermocatalytic methane decomposition. Furthermore, significant catalytic stability was observed with n-Ni/SiO2 at 500 °C and 600 °C. While, the rapid deactivation of the n-Fe/SiO2 and n-Co/SiO2 catalysts are attributed to particle agglomeration and the irregular formation of nano-carbon due to metal fragmentation. Physical and chemical characteristics of the produced nano-catalysts were investigated by N2 adsorption-desorption measurement (BET), X-ray diffraction (XRD), transmission electron microscopy (TEM) and hydrogen-temperature programmed reduction (H2-TPR). Produced nano-carbon were inspected with TEM, FESEM and XRD. This journal is © The Royal Society of Chemistry.

Sudamalla P.,Indian National Institute of Engineering | Matheswaran M.,Indian National Institute of Engineering | Saravanan P.,University of MalayaKuala Lumpur
Sustainable Environment Research | Year: 2012

An adsorbent prepared from mango seed was used to study its sorption potential on removing Crystal Violet dye from aqueous solution. The influences of operating parameters like pH, temperature, initial concentration and adsorbent dosage on dye adsorption were studied. A maximum dye removal of 95% was achieved with an initial concentration of 10 mg L-1. The percentage removal was mathematically described as a function of experimental parameters and was modeled through response surface methodology. The results show that the responses of color removal in adsorption of dyes were significantly affected by the synergistic effect of linear term of time and dosage and the quadratic term of temperature and time. A 24 full factorial design of experiments was adopted and statistical analysis was performed in the form of the analysis of variance and Student's t-test, which gave good interpretation in terms of interaction of experimental parameters. The interaction of the parameters temperature, pH, dye concentration and adsorbent dosage on Crystal Violet removal is also highly significant with confidential level > 99%. © 2012, Chinese Institute of Environmental Engineering. All rights reserved.

Aris M.H.,University of MalayaKuala Lumpur | Annuar M.S.M.,University of MalayaKuala Lumpur | Ling T.C.,University of MalayaKuala Lumpur
Polymer Degradation and Stability | Year: 2016

Lipase-catalyzed hydrolysis of poly(ɛ-caprolactone) (PCL) in toulene was investigated. PCL with number-average molecular weight (Mn) 10,000 g mol−1 was hydrolyzed using immobilized Candida antarctica lipase B (CALB). The increase in PCL concentration led to a decrease in degradation rate. Enhanced rate was observed when reaction temperature was increased from 30 to 50 °C. Enzymatic chain scission of PCL yielded cyclic dicaprolactone, tricaprolactone, tetracaprolactone and oligomers with Mn less than ∼1000 g mol−1. Catalytic formation of cyclic lactones via back-biting mechanism in low water content environment was attributed to CALB. Its hydrolysis of PCL displayed consecutive random- and chain-end scission with time from detailed thermal, molecular weight and structural analyses. Apparent activation energy, Ea for hydrolysis was 45 kJ mol−1 i.e. half of that reverse reaction. Dicaprolactone and oligomers from hydrolysis readily re-polymerized to produce mid-range polymer with Mn 1400 g mol−1 after 36 h in the same reaction medium. © 2016 Elsevier Ltd

M'Ng J.C.P.,University of MalayaKuala Lumpur | Mehralizadeh M.,University of MalayaKuala Lumpur
PLoS ONE | Year: 2016

The motivation behind this research is to innovatively combine new methods like wavelet, principal component analysis (PCA), and artificial neural network (ANN) approaches to analyze trade in today's increasingly difficult and volatile financial futures markets. The main focus of this study is to facilitate forecasting by using an enhanced denoising process on market data, taken as a multivariate signal, in order to deduct the same noise from the open-high-low-close signal of a market. This research offers evidence on the predictive ability and the profitability of abnormal returns of a new hybrid forecasting model using Wavelet-PCA denoising and ANN (named WPCA-NN) on futures contracts of Hong Kong's Hang Seng futures, Japan's NIKKEI 225 futures, Singapore's MSCI futures, South Korea's KOSPI 200 futures, and Taiwan's TAIEX futures from 2005 to 2014. Using a host of technical analysis indicators consisting of RSI, MACD, MACD Signal, Stochastic Fast %K, Stochastic Slow %K, Stochastic %D, and Ultimate Oscillator, empirical results show that the annual mean returns of WPCA-NN are more than the threshold buy-and-hold for the validation, test, and evaluation periods; this is inconsistent with the traditional random walk hypothesis, which insists that mechanical rules cannot outperform the threshold buy-andhold. The findings, however, are consistent with literature that advocates technical analysis. © 2016 Chan Phooi M'ng, Mehralizadeh.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Vignesvaran K.,University of MalayaKuala Lumpur | Alias Z.,University of MalayaKuala Lumpur
Archives of Insect Biochemistry and Physiology | Year: 2016

Drosophila melanogaster glutathione S-transferase D3 (DmGSTD3) has a shorter amino acid sequence as compared to other GSTs known in the fruit flies. This is due to the 15 amino acid N-terminal truncation in which normally active amino acid residue is located. The work has made use of homology modeling to visualize the arrangement of amino acid side chains in the glutathione (GSH) substrate cavity. The identified amino acids were then replaced with amino acids without functional groups in the side chains and the mutants were analyzed kinetically. Homology modeling revealed that the side chains of Y89 and Y97 were shown facing toward the substrate cavity proposing their possible role in catalyzing the conjugation. Y97A and Y89A GSH gave large changes in Km (twofold increase), Vmax (fivefold reduction), and Kcat/Km values for GSH suggesting their significant role in the conjugation reaction. The replacement at either positions has not affected the affinity of the enzyme toward 1-chloro-2,4-dinitrobenzene as no significant change in values of Kmax was observed. The replacement, however, had significantly reduced the catalytic efficiency of both mutants with (Kcat/Km)GSH and (Kcat/Km)CDNB of eight- and twofold reduction. The recombinant DmGSTD3 has shown no activity toward 1,2-dichloro-4-nitrobenzene, 2,4-hexadienal, 2,4-heptadienal, p-nitrobenzyl chloride, ethacrynic acid, and sulfobromophthalein. Therefore, it was evident that DmGSTD3 has made use of distal amino acids Y97 and Y89 for GSH conjugation. © 2016 Wiley Periodicals, Inc.

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