Showing papers by "National University of Malaysia published in 2011"

A Review on Heavy Metals (As, Pb, and Hg) Uptake by Plants through Phytoremediation

Abstract: Heavy metals are among the most important sorts of contaminant in the environment. Several methods already used to clean up the environment from these kinds of contaminants, but most of them are costly and difficult to get optimum results. Currently, phytoremediation is an effective and affordable technological solution used to extract or remove inactive metals and metal pollutants from contaminated soil and water. This technology is environmental friendly and potentially cost effective. This paper aims to compile some information about heavy metals of arsenic, lead, and mercury (As, Pb, and Hg) sources, effects and their treatment. It also reviews deeply about phytoremediation technology, including the heavy metal uptake mechanisms and several research studies associated about the topics. Additionally, it describes several sources and the effects of As, Pb, and Hg on the environment, the advantages of this kind of technology for reducing them, and also heavy metal uptake mechanisms in phytoremediation technology as well as the factors affecting the uptake mechanisms. Some recommended plants which are commonly used in phytoremediation and their capability to reduce the contaminant are also reported.

Applying the Theory of Planned Behavior (TPB) in halal food purchasing

Abstract: Purpose – In this study, Ajzen's Theory of Planned Behavior is used as a theoretical framework with the aim of extending prior research examining halal food purchasing behavior in Malaysia.Design/methodology/approach – Data are collected through self‐administered questionnaires. This paper uses multiple regression analysis to identify the factors affecting halal food purchasing behavior of Malaysian consumers.Findings – The multiple regression analysis results indicate that all factors have positive and significant influence on halal food purchasing intention.Research limitations/implications – Like other empirical studies, this study is not without its limitations. The sample size itself is relatively small. The study can be strengthened by increasing the sample size and including participants in other geographical areas. This study also considered only three antecedents of halal food purchasing among consumers in Malaysia. As Malaysia is actually trying to play for a bigger role in the halal industry, m...

Recent advances in flat plate photovoltaic/thermal (PV/T) solar collectors

Abstract: Flat plate photovoltaic/thermal (PV/T) solar collector produces both thermal energy and electricity simultaneously. This paper presents the state-of-the-art on flat plate PV/T collector classification, design and performance evaluation of water, air and combination of water and/or air based. This review also covers the future development of flat plate PV/T solar collector on building integrated photovoltaic (BIPV) and building integrated photovoltaic/thermal (BIPVT) applications. Different designs feature and performance of flat plate PV/T solar collectors have been compared and discussed. Future research and development (R&D) works have been elaborated. The tube and sheet design is the simplest and easiest to be manufactured, even though, the efficiency is 2% lower compared to other types of collectors such as, channel, free flow and two-absorber. It is clear from the review that for both air and water based PV/T solar collectors, the important key factors that influenced the efficiency of the system are the area where the collector covered, the number of passes and the gap between the absorber collector and solar cells. From the literature review, it is obvious that the flat plate PV/T solar collector is an alternative promising system for low-energy applications in residential, industrial and commercial buildings. Other possible areas for the future works of BIPVT are also mentioned.

Is religiosity an important determinant on Muslim consumer behaviour in Malaysia

Abstract: Purpose – The purpose of this paper is to examine the effect of religiosity on Muslim consumer behaviour and on purchasing decision.Design/methodology/approach – Survey comprised a sample of 232 Muslims from the middle‐ and upper‐income groups who work in Shah Alam and Bangi in the Selangor state of Malaysia.Findings – The findings indicate that religious Muslims in Shah Alam and Bangi area consider Islam as their source of reference and they spend moderately, as commanded by Allah in the Quran. This study confirms that religiosity acts as a full mediating role in the relationship between relative and contextual variables, and purchase behaviour of Muslim consumers.Originality/value – The paper's interesting findings serve to remind entrepreneurs that they cannot neglect the element of religion in their marketing activities, particularly in the development of products.

Spatial water quality assessment of Langat River Basin (Malaysia) using environmetric techniques.

Abstract: This study investigates the spatial water quality pattern of seven stations located along the main Langat River. Environmetric methods, namely, the hierarchical agglomerative cluster analysis (HACA), the discriminant analysis (DA), the principal component analysis (PCA), and the factor analysis (FA), were used to study the spatial variations of the most significant water quality variables and to determine the origin of pollution sources. Twenty-three water quality parameters were initially selected and analyzed. Three spatial clusters were formed based on HACA. These clusters are designated as downstream of Langat river, middle stream of Langat river, and upstream of Langat River regions. Forward and backward stepwise DA managed to discriminate six and seven water quality variables, respectively, from the original 23 variables. PCA and FA (varimax functionality) were used to investigate the origin of each water quality variable due to land use activities based on the three clustered regions. Seven principal components (PCs) were obtained with 81% total variation for the high-pollution source (HPS) region, while six PCs with 71% and 79% total variances were obtained for the moderate-pollution source (MPS) and low-pollution source (LPS) regions, respectively. The pollution sources for the HPS and MPS are of anthropogenic sources (industrial, municipal waste, and agricultural runoff). For the LPS region, the domestic and agricultural runoffs are the main sources of pollution. From this study, we can conclude that the application of environmetric methods can reveal meaningful information on the spatial variability of a large and complex river water quality data.

Smart packaging: sensors for monitoring of food quality and safety

Abstract: The development of chemical sensors and biosensors over several decades has been investigated resulting in novel and very interesting sensor devices with great promise for many areas of applications including food technology. The incorporation of such sensors into the food packaging technology has resulted what we call smart or intelligent packaging. These are truly integrated and interdisciplinary systems that invoke expertise from the fields of chemistry, biochemistry, physics and electronics as well as food science and technology. Smart packaging utilises chemical sensor or biosensor to monitor the quality & safety of food from the producers to the costumers. This technology can result in a variety of sensor designs that are suitable for monitoring of food quality and safety, such as freshness, pathogens, leakage, carbon dioxide, oxygen, pH, time or temperature. Thus, this technology is needed as on-line quality control and safety in term of consumers, authorities and food producers, and has great potential in the development of new sensing systems integrated in the food packaging, which are beyond the existing conventional technologies, like control of weight, volume, colour and appearance.

Perspectives of double skin façade systems in buildings and energy saving

Abstract: One of the most important methods of saving energy in a building is by carefully designing its facade. A ‘double skin facade’ is optimally one of the best options in managing the interaction between the outdoors and the internal spaces. It also provides some architectural flexibility to the design. Recently it has received much attention as opposed to the more typically glazed curtain wall. This is because of its ability to efficiently reduce energy and therefore saves cost. The amount of energy saved depends on the climate and the design chosen. The design of the DSF involves decisions on geometric parameters, glass selection, ventilation strategy, shading, daylighting, aesthetics, wind loads, and maintenance and cleaning cost expectations. DSF has an impact on several aspects of the design phase of a building. For example, thermal properties, acoustic characteristics and daylighting are affected in the exploitation phase of the building. In addition, in terms of building safety point of view, fire propagation maintenance or glazing thermal break must be taken into account. Currently, little work has been done on the behaviour of DSFs in hot and humid climates. This paper shall review previous studies made on double skin facade systems (DSFS) in buildings.

An Empirical Study of Factors Affecting Electronic Commerce Adoption among SMEs in Malaysia

Abstract: This study empirically examines determinants of E-commerce adoption by Malaysian Small and Medium-sized Enterprises. Research model for this study was drawn on the literature on information and communication technology, Information system, and electronic data interchange. This study tested seven hypotheses on factors that influence e-commerce adoption with empirical data from a sample of 200 SMEs in Malaysia. The findings show that relative advantage, compatibility, organizational readiness, manager's characteristics, and security have significant impact on e-commerce adoption. The study provides a clear understanding of manager's perception about e-commerce adoption in their businesses. This study is important in a global context, as SMEs in Malaysia are going for exporting their product in the global marketplace.

Total phenolic content and antioxidant activity of kesum (Polygonum minus), ginger (Zingiber officinale) and turmeric (Curcuma longa) extract

Abstract: Herb and spices namely kesum, ginger and turmeric were extracted by using juice extractor without the additional of solvent. These herb and spices were determined for moisture content and the extracts were analyzed for total phenolic content (TPC) and antioxidant activity (DPPH radical scavenging assay and FRAP ferric-reducing antioxidant power assay). The yield of kesum, ginger and turmeric extraction was 23.6%, 58.6% and 66.4%, respectively. The results showed that, there was significant difference (P < 0.05) in total phenolic content and antioxidant activity for kesum, ginger and turmeric extracts. Kesum extract had the highest total phenolic content followed by ginger and turmeric extract. A significant and positive high Pearson's correlations between TPC and DPPH assay (r = 0.86) and between TPC and FRAP assay (r = 0.91) respectively was observed for all plants extracts. This indicated that phenolic compounds were the main contributor of antioxidant activity in plants. However, there was no synergistic effect observed for all plants extract mixture.

Flow and heat transfer over a rotating porous disk in a nanofluid

Abstract: The steady flow of an incompressible viscous fluid due to a rotating disk in a nanofluid is studied. The transformed boundary layer equations are solved numerically by a finite difference scheme, namely the Keller-box method. Numerical results for the flow and heat transfer characteristics are obtained for various values of the nanoparticle volume fraction parameter φ and suction/injection parameter h0. Two models for the effective thermal conductivity of the nanofluid, namely the Maxwell–Garnett model and the Patel model, are considered. It is found that for the Patel model, the heat transfer rate at the surface increases for both suction and injection, whereas different behaviors are observed for the Maxwell–Garnett model, i.e. increasing the values of φ leads to a decrease in the heat transfer rate at the surface for suction, but increases for injection. The results of this study can be used in the design of an effective cooling system for electronic components to help ensure effective and safe operational conditions.

Antioxidant Activity of Pink-Flesh Guava (Psidium guajava L.): Effect of Extraction Techniques and Solvents

Abstract: The effect of commonly used techniques and solvents in the antioxidant activities of pink-flesh guava fruit were studied. The extraction techniques compared were homogenization, shaking, sonication, magnetic stirring, and maceration for 1, 2, and 3 days. The solvent systems used were methanol, ethanol, and acetone at three different concentrations (50%, 70%, and 100%) and with 100% distilled water. The antioxidant activity of the fruit was evaluated using Folin–Ciocalteu index, ferric-reducing antioxidant power assay, and 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging capacity. Ultrasonic and homogenization were the best techniques to extract the antioxidant from guava fruit. Homogenization technique was found to be the most convenient exhaustive and time-saving extraction technique. Results showed that the extracting solvent significantly (P < 0.05) altered the antioxidant property estimations of pink-flesh guava fruit. Pure solvents were inefficient extraction media for antioxidant. Enhanced extraction yields were obtained from solvent containing higher water concentrations and 50% acetone is a recommended solvent for extracting antioxidants compounds from pink-flesh guava fruit. High correlations between phenolic compositions and antioxidant activities of pink-flesh guava extracts were observed. High levels of antioxidant activities were detected in pink-flesh guava, indicating that the fruit may serve as an excellent dietary source of natural antioxidants.

Review of solar air collectors with thermal storage units

Abstract: Thermal energy storage is one of the most efficient ways to store solar energy for heating air by energy collected from sun. The relative studies are involved to the type of collection with the type of storage, i.e. separated to each other or integrated. This review summarizes the previous works on solar air heaters with storage materials include greenhouse, encapsulation, and the latest development in the solar thermal energy storage with air as a heat transfer fluid. The recent researches focused on the phase change materials (PCMs), as latent heat storage is more efficient than sensible heat storage. It has been appeared that PCM with high latent heat and suitable geometry are required for optimum thermal performance of solar air heater. The recent designs of solar air heaters with thermal storage units reduced the cost and the volume when integrated in one product.

Effect of ethanol concentration, extraction time and extraction temperature on the recovery of phenolic compounds and antioxidant capacity of Orthosiphon stamineus extracts

Abstract: Optimization of phenolic extraction from Orthosiphon stamineus was carried out in present study by investigating the effects of ethanol concentration (0-100%, v/v), extraction time (60-300 min) and extraction temperature (25-65oC) on the phenolic recovery using single factor experiment. Total phenolic content (TPC), total flavonoid content (TFC) and condensed tannins content (CTC) were used for determination of phenolic compounds while 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical-scavenging capacity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity were used for evaluating the antioxidant capacities of crude extract. Experimental results showed that all extraction parameters had significant (p<0.05) effect on phenolic contents (TPC, TFC and ABTS) and antioxidant capacities (ABTS and DPPH) of crude extract. The optimized conditions for phenolic extraction were 40% ethanol for 120 min at 65oC with values of 2003.4 mg GAE/100 g DW for TPC, 1611.9 mg CE/100 g DW for TFC, 202.4 mg CE/100 g DW for CTC, 765.4 μmol TEAC/100 g DW for ABTS and 2180.9 μmol TEAC/100 g DW for DPPH. DPPH was found to be positively significantly correlated with TPC but negatively significantly correlated with CTC under the influence of ethanol concentration. As a function of extraction temperature, all antioxidant compounds assays (TPC, TFC and CTC) were negatively correlated with antioxidant capacities (ABTS and DPPH).

An Empirical Study of Success Factors of Women Entrepreneurs in Southern Region in Malaysia

Abstract: This study investigates the key factors affecting success of women entrepreneurs in Southern region in Malaysia. Data was collected using a self administered questionnaire that was distributed through mail survey. Multiple regression analysis was used as a more suitable methodology to identify the important determinants of success of women entrepreneurs. The results suggest that family support, social ties and internal motivation affect positively and significantly to the success of women entrepreneurs in the small business. The survey result also shows that women entrepreneurs having problem when they enter into the business. The implications of this study are discussed along with some recommendations.

The Antioxidant Activity of New Coumarin Derivatives

Abstract: The antioxidant activity of two synthesized coumarins namely, N-(4,7-dioxo-2- phenyl-1,3-oxazepin-3(2H,4H,7H)-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 5 and N-(4-oxo-2-phenylthiazolidin-3-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 6 were studied with the DPPH, hydrogen peroxide and nitric oxide radical methods and compared with the known antioxidant ascorbic acid. Compounds 5 and 6 were synthesized in a good yield from the addition reaction of maleic anhydride or mercaptoacetic acid to compound 4, namely N'-benzylidene-2-(2-oxo-2H-chromen-4-yloxy)acetohydrazide. Compound 4 was synthesized by the condensation of compound 3, namely 2-(2-oxo-2H-chromen-4-yloxy) acetohydrazide, with benzaldehyde. Compound 3, however, was synthesized from the addition of hydrazine to compound 2, namely ethyl 2-(2-oxo-2H-chromen-4-yloxy)acetate, which was synthesized from the reaction of ethyl bromoacetate with 4-hydroxycoumarin 1. Structures for the synthesized coumarins 2-6 are proposed on the basis of spectroscopic evidence.

The Impact of Anthropogenic Heat on Formation of Urban Heat Island and Energy Consumption Balance

Abstract: This paper investigates the impact of anthropogenic heat on formation of urban heat island (UHI) and also determines which factors can directly affect energy use in the city. It explores literally the conceptual framework of confliction between anthropogenic heat and urban structure, which produced UHI intensity and affected energy consumption balance. It then discusses how these two factors can be affected and gives implication to the city and then focuses on whether actions should be taken for balancing adaptation and mitigation of UHI effects. It will be concluded by making the three important strategies to minimise the impact of UHI on energy consumption: landscaping, using albedo materials on external surfaces of buildings and urban areas, and promoting natural ventilation.

Advances in liquid based photovoltaic/thermal (PV/T) collectors

Abstract: In order to get more power and heat from PV/T system, it is necessary to cool the PV cell and decrease its temperature. This is not an easy task especially in hot and humid climate areas. There is a lack of an effective cooling strategy of PV/T panels. The liquid based photovoltaic thermal collector systems are practically more desirable and effective than air based systems. Temperature fluctuation in liquid based PV/T is much less than the air based PV/T collectors which subjected to variation in solar radiation levels. In this study a review of the available literature on PV/T collector systems which utilize water and refrigerant (working fluid) as heat removal medium for different applications has been conducted. Future direction of water-cooled and refrigerant hybrid photovoltaic thermal systems was presented. This study revealed that the direct expansion solar-assisted heat pump system achieved better cooling effect of the PV/T collector.