13474 research outputs found
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Physical and toxicological properties of water treatment residue incorporated clay bricks / Puspanathan Krishnan
No full textWater Treatment Residue (WTR) disposal is a major issue in most parts of the world
as well as in Malaysia due to its huge quantity. It is estimated that WTR weighs at 2 %
of the total treated water quantity. In 2014, Malaysia produces 16,000 million L/d
(MLD) of drinking water. Only 30 % of the Malaysia Water Treatment Plant operates
with sludge treatment and treated effluent discharge to water course. The characteristic
of the WTR depends on the quality of river water (water source) and the type of
coagulants used. Common chemical coagulants used in Malaysia are alum (AlSO4) and
poly-aluminum chloride (PAC). These chemical coagulants generates residue which
containing aluminium which is classified as scheduled wastes (SW 204) under
Environmental Quality Act 1974, Environmental Quality (Schedule Wastes) Regulation
2005. This research study focused to reuse a portion of WTR as raw material which can
be used as plasticizer with laterite earth for clay bricks manufacturing process. The
research project investigated physical and mechanical properties of WTR Bricks such as
compressive strength, efflorescence effects, bulk density, water absorption, weight
reduction according to BS/EN Standard, loss of ignition, toxicity and ecotoxic analysis.
The results indicates best combination for laboratory size brick of 40% WTR – 60%
Laterite and commercial size bricks 30% WTR – 70% Laterite.”
Generating an adaptive and robust walking pattern for prosthetic ankle-foot utilizing a nonlinear autoregressive network with exogenous inputs / Hamza Al Kouzbary
No full textMany challenges are associated with the development of powered lower limb prostheses, ranging from their mechanical design to their control system. Many studies on the use of control algorithms in the field of rehabilitation robotics have attempted to mimic the behavior of an intact lower limb with different walking speeds over diverse terrains and used different control structures and logic to achieve this overarching goal. Recently, most of these studies tend to use a hierarchical control structure with three control levels. This three-level control structure has at least one element of discrete transition properties that requires many sensors to improve classification accuracy. However, these sensors also lead to higher computational load and costs. In this study, a developed artificial neural network capable of generating dynamic control signals of the missing foot, user-independent and free-mode method using minimum sensory feedback signals was proposed to eliminate the need to switch among different controllers. A database was constructed using four OPAL wearable devices (Mobility Lab, APDM Inc., USA) for seven able-bodied subjects. The gait of each subject at three ambulation speeds during ground-level walking was recorded to train a non-linear autoregressive network with an exogenous input recurrent neural network (NARX RNN) for estimating foot orientation (angular position) in the sagittal plane using shank angular velocity as external input. The trained NARX RNN estimated the foot orientation of all subjects at different walking speeds over a flat terrain with an average root mean square error of 2.1°±1.7°. The minimum correlation between the estimated and measured values was 86% which indicated the high similarity between the estimated and measured foot trajectories. Moreover, results of the t-test show that the error is normally distributed with a high certainty level (0.88 minimum p-value). In addition, the extreme value distribution of the measured
and estimated data of all subjects were quite identical which indicates probabilistic consistency of the model. NARX RNN capability to generate the dynamic control signals for different walking cadences will reduce the risk of amputees falling or stumbling when a wrong classification occurs using the conventional three-level controllers
Synthesis and characterization of semicarbazide and thiosemicarbazide bearing butylated hydroxytoluene moiety for antioxidant application / Syabilah Sazeli
No full textNew multipotent antioxidants (MPAOs) semicarbazides and thiosemicarbazides bearing thiolated butylated hydroxytoluene (BHT) moiety were synthesized by a simple reaction between acid hydrazide, aryl isocyanates, and isothiocyanates. The antioxidant activity of these compounds was evaluated by using in vitro α, α-diphenyl-β-picrylhydrazyl (DPPH) assay. Thiosemicarbazides 5a’-h’ were found more active in free radical scavenging activity than semicarbazides 5a-h. Compound 2-(2-((3,5-di-tert-butyl-4-hydroxybenzyl)thio)acetyl)-N-(naphthalen-2-yl)hydrazine-1-carbothioamide 5f’ showed the best antioxidant activity against DPPH radical (IC50 of 25.47 ± 0.42 μM) compared to the standard BHT. Compound 5f’ and 2-(2-((3,5-di-tert-butyl-4-hydroxybenzyl)thio)acetyl)-N-(naphthalen-2-yl)hydrazine-1-carboxamide 5f were blended into trimethylolpropane trioleate (TMPTO) synthetic lube oil subjected for isothermal differential scanning calorimetric (DSC) measurement at 125 oC and 150 oC to investigate their oxidative stability. At 125 oC, TMPTO blended with 0.25 wt.% of 5f’ showed 2 and 1.5 times higher oxidative stability than that of BHT and 5f, respectively. It was postulated that the promising oxidative stability of 5f’ was due to strong auto-synergistic effect
Mechanical and microstructure analysis of copper to copper foam brazing using copper-tin nickel-phosphorus amorphous filler alloys / Nur Amirah Mohd Zahri
No full textHeat exchangers made with metal foams elements have great potential in thermal applications as they have high heat flux cooling due to their large surface to volume ratio. However, finding an effective joining method to incorporate metal foams into heat exchanger designs is very challenging and has become a topic of interest in brazing technology. In this study, the brazing of copper foam to solid copper using different copper-tin-nickel-phosphorus (Cu-Sn-Ni-P) amorphous filler alloys was investigated. The parameters evaluated included the pore densities of Cu foams (pore per inch- PPI), the fillers metal and the brazing temperatures. The resultant joints were evaluated for compressive and shear strengths to determine their mechanical reliabilities. Microstructural evaluations were conducted on the brazed interface using Scanning electron microscope (SEM), X-ray diffraction (XRD) and Energy-dispersive X-ray spectroscopy (EDX) (point, line and area mapping). Finally, the corrosion behaviours of crystalline filler alloys and Cu/Cu foam/Cu brazed joints were analysed using electrochemical potentiodynamic polarisation and immersion tests, respectively. It was found that the compressive strengths of brazed Cu/Cu foam/Cu increase with increasing foam pore density. The highest compressive strength of 14.4 MPa was obtained for 50 PPI Cu foam brazed sample followed 25 PPI and 15 PPI Cu foams. This increase in compressive strength was due to the dense interconnected branches in 50 PPI Cu foam. In contrast, the highest shear strength of 3.7 MPa was obtained for brazed joint sample of 15 PPI Cu foam as compared to 25 PPI (3.3 MPa) and 50 PPI (2.8 MPa) Cu foams. This was due to the larger area of interconnected branches in 15 PPI Cu foam. SEM images revealed increases in cavities formation in the joint interface with increasing Cu foam pore density which correspond with the decrease in brazing joint strengths. EDX and XRD analysis have shown the concentrations of Cu, Cu6Sn5, Cu3P and Ni3P in the joint. EDX line scanning has verified the diffusion of P element into the Cu foam, which would have strengthened the Cu foam branches and contribute to its high compressive strength properties. The electrochemical potentiodynamic polarisation tests have shown that the Cu-9.7Sn-5.7Ni-7.0P filler has less noble corrosion potential (Ecorr) which make it prone to corrosion attack. However, Cu-9.7Sn-5.7Ni-7.0P filler has a more negative of corrosion current density (Icorr), indicating low corrosion rate and high corrosion resistance. This observation agrees with the immersion test of Cu/Cu foam/Cu using Cu-9.7Sn-5.7Ni-7.0P filler, which resulted in the thickest patina layer formation (initially formed by an aggressive corrosion) protecting the interface from further corrosion attack (high corrosion resistant). By considering the aspect of manufacturing, Cu foam strength, brazed joint strength, microstructure and corrosion performance, it is proposed that Cu/Cu foam /Cu with 15 PPI Cu foam using Cu-9.7Sn-5.7Ni-7.0P filler at brazing temperature of 680 °C would be the most suitable configuration for use in heat exchanger applications
Catalytic gas-phase hydrodeoxygenation of phenol over silica supported zinc catalysts at atmospheric pressure / Hamed Pourzolfaghar
No full textHydrodeoxygenation (HDO) is a promising process for bio-oil upgrading derived from biomass wood. Although the result of the process performance is encouraging, further investigation still continues especially in obtaining the best type of catalyst in an atmospheric process condition. In this study, the HDO of phenol-based bio-oil catalyzed by Zn/SiO2 under atmospheric H2 pressure was investigated in a continuous fixed bed reactor. The physicochemical properties of the catalysts were surveyed by XRD, BET, ICP‐OES, EDX, H2-TPD, NH3‐TPD, TGA, H2-TPR, and FESEM. Following, the effects of various process parameters on the conversion efficiency and selectivity of the catalytic reaction products have been investigated. Finally, the stability and regenerability of the catalysts as well as the mechanism of the reaction have been surveyed.
Characteristics outcomes indicated that the prepared catalyst is able to convert the phenol into aromatic hydrocarbons in low pressure hydrogen. The optimization study using various independent variables revealed that the hydrogen volumetric flow rate slightly affects product distribution and conversion efficiency. Process temperature increases the reaction conversion efficiency without changing the selectivity. The optimization study indicated that a process with 3% Zn/SiO2 as the catalyst, temperature at 500 ˚C, WHSV of 0.32 h-1, and H2 volumetric flow rate of 150 mL/min provides the highest possible conversion efficiency of phenol into aromatic hydrocarbons. The time-on-stream investigation illustrated that the silica-supported zinc was highly active up to 240 min of phenol HDO, with a conversion efficiency up to 80%, and after 420 min of TOS, the activity decreased to around a conversion rate of 43%. Reusability tests revealed that the catalyst displayed outstanding reusability and could be regenerated fully after four reusing rounds
Synthesis and characterization of carbon monoxide-releasing molecules (CORMS) as bioactive agents / Lee Shiaw Xian
No full textDespite the toxicity of CO, the development of carbon monoxide-releasing molecules (CORMs) has gained increasing popularity since the discovery of the potential therapeutic properties of CO towards human body. In this study, four series of UV activable photoCORMs with the general structure of ML(CO)4 and M2L(CO)8 (Bimetallic), where M = Cr, Mo, and W, were synthesized by reacting group 6 hexacarbonyl (Cr, Mo, and W) with four new Schiff base ligands based on phenanthroline containing fluorene, 2-hydroxynaphthalene, 2-hydroxy-3-methoxy and phenylene-phenanthroline as side groups (Correspond to L1, L2, L3, and L4). All the synthesized photoCORMs release CO in the presence of UV light (365 nm). All compounds were characterized by FT-IR, 1H-NMR, 13C-NMR, and CHN elemental analysis. Twelve X-ray crystal structures were obtained out of the sixteen synthesized compounds. The half-life and the number of CO released of the synthesized photoCORMs were studied using a three-layered myoglobin solution which is a modified version of the standard myoglobin assay. Chromium photoCORMs C1, C2, C3, and C4 had much shorter half-life compared to molybdenum and tungsten photoCORMs. Molybdenum and tungsten photoCORMs were stable in 10% DMSO-PBS solution in the absence of light over 48 hours but chromium photoCORMs showed signs of decomposition. All compounds were subjected to anticancer and antimicrobial studies in the absence and presence of UV light illumination. The synthesized photoCORMs showed notable photo-induced cytotoxicity against human colorectal cancer cell lines (HT-29 and HCT 116) and showed remarkedly high selectivity when tested against the human normal colon fibroblast (CCD18-Co). However, all photoCORMs were generally non-active against all the tested microbes and only the second and the third series photoCORMs displayed slight photo-induced antimicrobial activities. The SwissADME simulation predicted that most of the synthesized compounds possess “drug-like” properties
Life cycle assessment for the production of refined palm products and palm-based biofuels / Yung Chee Liang
No full textPalm oil is an important commodity for Malaysia which contributes 5-7% to the national gross domestic product. Being the second-largest producer in the world, crude palm oil (CPO) production in Malaysia has reached 19.858 million tonnes in 2019. Majority of the CPO produced are refined and fractionated in the local refineries before export or further downstream applications. The main objective of the study is to determine the environmental impacts of palm oil refining, fractionation and biofuels production in Malaysia. For palm oil refining and fractionation, the inventory data are derived from primary data supplied by six palm oil refineries for a period of five years operation. For biodiesel production, the inventory data are derived from primary data collected from six commercial biodiesel plants for a period of three years operation. The inventory data for hydroprocessing are referred to pilot plant operation data due to no commercial hydroprocessing activity in the country. Life cycle assessment (LCA) is conducted using SimaPro software version 9.1.1.1 and impact assessment is performed according to ReCiPe 2016 (Hierarchist) methodology. In the gate-to-gate LCA, bleaching earth, electricity and transportation of CPO are the main contributors to environmental impacts in the palm oil refining stage while RBD palm oil is the single major contributor to the palm oil fractionation stage. Improvement in the transportation of CPO can reduce the environmental impacts effectively in the refinery subsystem through sourcing of CPO from nearby palm oil mills and the use of modern Euro 5-compliant trucks. Methanol, acids and sodium methoxide (transesterification catalyst) are the three major contributors to the environmental impacts in the biodiesel subsystem. Hydrogen and electricity are the two important contributors to the hydroprocessing subsystem. Allocation based on economic value is suitable for LCA of palm oil refining, fractionation and biodiesel production due to different economic values of the products and co-products. Energy allocation based on lower heating values is suitable for the hydroprocessing subsystem since the products and co-products are energy-based. Sensitivity analysis on allocation procedures at refining and fractionation shows an insignificant difference between allocation based on mass and energy content simply due to the similar energy content of the refined and fractionated palm products. Sensitivity analysis on prices movement shows a negligible variation on the allocated environmental impacts for both the refinery and the biodiesel subsystems. The impact assessment of the palm biodiesel subsystem shows that the replacement of fossil-based methanol with biomethanol derived from biogas is the preferred mitigation option. 19% reduction in global warming impact and 60% saving of fossil resources are anticipated for the gate-to-gate impact assessment. The cradle-to-gate and cradle-to-grave LCA highlight the important contribution of biogas emissions from the palm oil mills subsystem to the overall global warming impact. Biogas capturing at palm oil mills and the replacement of fossil-based methanol are the two important strategies to reduce the potential environmental impacts
Power elites and state-business relations: Malaysia-China selected belt and road initiative projects / Khaw Mooi Hock
No full textThis study focuses on state-state-business ties, a new phenomenon shaped by how local power elites (LPEs) collaborate with Chinese transnational corporate elites (TCEs) to implement infrastructure projects related to China’s Belt and Road Initiative (BRI). These LPE-TCE links, in turn, have led to the creation of novel forms of state-business relations (SBRs), with diverse outcomes and implications. In Malaysia, these state-state-business ties, forged by both countries for their respective business enterprises, were primarily a consequence of an interesting confluence of two major events, which took place between 2014 and 2016: 1) Malaysia’s 1Malaysia Development Berhad (1MDB) scandal; and 2) the introduction of China’s BRI. These events then witnessed leaders of two single-dominant parties (SDPs), the United Malays National Organisation (UMNO) and Chinese Communist Party (CCP), coming together to pursue their respective economic and political objectives. This thesis draws attention to this important and new phenomenon that offers interesting theoretical insights in both elite- and SBR-related studies. The conventional wisdom of homogenised SBRs is built on, by indicating that, in practice, state-business ties are extremely heterogeneous. This study has developed a conceptual framework that explains how state-state-business ties, forged by two countries, both led by SDPs, that control their respective enterprises, have contributed to unique SBRs, created to undertake BRI projects, which in turn are driven by specific LPE-TCE links. Case studies are employed to trace empirically why the three BRI projects in Malaysia were implemented on a non-transparent basis. These studies provide insights into how disparate forms of SBR-based institutional architecture function, not only at the federal level, but also in different states in Malaysia, with links externally to Chinese enterprises. In the process, it draws attention to the emergence of diverse types of power and inter- and intra-elite relationship issues of different LPEs, like elite unity, elite contestation, and elite settlement, which have contributed to the creation of dissimilar SBRs. This study notes that different LPEs, as key actors in the state, might have turned effective and collaborative SBRs, fashioned to implement the three BRI projects, into economic endeavours that also feature ineffective and collusive relationships, characterised by rent-seeking behaviour. This study also highlights that key UMNO elites and Chinese state-owned enterprises (SOEs) appear to be central in these novel SBRs, an issue that has had major implications for the Malaysian economy, as well as its political system
A coalition model for efficient indexing in wireless sensor network with random mobility / Hazem Jihad Ali Badarneh
No full textWireless Sensor Networks grow rapidly due to the sensing and scanning capabilities, in addition to the capabilities of Wireless Sensor Networks nodes to move randomly and send periodic reports. In such environments, the periodic reports of sensors' nodes contain the transmission attributes that represent the transmission locations and time. Because of these attributes, it requires to be efficiently allocated and effectively processed. In the case of random mobile sensors, a huge number of packets are generated, which exacerbated the burden of indexing the mobile sensors' reports, because of dependability on packets' attributes. However, several studies have attempted to improve the Grid-based index-trees by dividing the network area into smaller areas called grids. The fundamental principle underlying the division is to construct the index structure by determining the mobile sensors that belong to each grid, then construct the index according to the attributes of the packet. Nevertheless, it is more practical to improve the indexing procedures of random mobile sensors, because of the following challenges. First, the high dependability on multi-attributes (location and time) of packets in random mobile sensors. Second, in a random mobile environment, it is required for registering the current grid location of each sensor and assign its destination periodically. Specifically, this thesis proposes an efficient model called Dynamic Static Coalition-based (DySta-Coalition for short) to improve the indexing procedures of random mobile sensors. The proposed model consists of Dynamic-Coalition framework, Static-Coalition algorithm, and Coalition-Based Index-Tree framework. Dynamic-Coalition framework establishes a relevance between sensors and gateways to construct dynamic blocks called dynamic-coalitions. The proposed framework aims to improve the indexing packets and mitigate the disseminated data. Static-Coalition algorithm rearranges the packets in each gateway, by source (location attribute). Accordingly, it arranges the packets, step-by-step before accumulated in the main server for indexing. Coalition-Based Index-Tree framework is an indexing process for random mobile sensors. Finally, the performance of DySta-Coalition model is comprehensively evaluated on various synthetic datasets with various parameters (number of mobile sensors, clusters, and dimensions) and metrics (packets delivery ratio, routing overhead, space cost overhead, index building time, and number of traversed nodes). First, evaluate Dynamic-Coalition framework and Static-Coalition algorithm, in terms of Average Routing Overhead and Packet Delivery Ratio. As well as, evaluate Coalition-Based Index-Tree framework in terms of the number of traversed nodes, space-cost overhead, and index building-time. The second evaluation divides into three scenarios. The first one evaluates Coalition-Based Index-Tree framework independently, without any effect from Dynamic-Coalition framework and Static-Coalition algorithm. The second and third scenarios evaluate the performance of Coalition-Based Index-Tree by examining the effects of Dynamic-Coalition framework and Static-Coalition algorithm on Coalition-Based Index-Tree framework. The evaluation results demonstrate that DySta-Coalition model can mitigate the disseminated packets, which results in minimizing dependability on the attributes of the packet. Furthermore, it is supreme according to the results of index building time and space cost overhead
Comparative study onneuroprotection of aqueous and ethanolicextracts of Calocybe indica (Purkayastha & Chandra) in neuro-2A-blastoma cell / Muhammad Taha Bennett
No full textMushrooms have gained worldwide popularity for both their nutritional and medicinal properties. Despite thousands of edible mushrooms worldwide, only a handful of mushrooms are available on a commercial scale or have been extensively studied for their therapeutic properties. A lot of research on health properties of mushrooms focus on chronic diseases such as cancer, heart disease and diabetes. In particular, a lot of research is currently focusing on neurodegenerative diseases such as Alzheimer’s disease. The current research focuses on Calocybe indica Purkayastha & Chandra (milky white mushroom), a relatively unknown mushroom. Fresh fruiting bodies of mushrooms were sliced then either freeze-dried or oven-dried before extracted using aqueous and ethanolic (99.8%) solvents. Cultures of mouse Neuro-2a-blastoma (N2a) cells were seeded into a 96-well plate and assessed by using a colorimetric 3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay with varying concentrations of the mushroom extracts (0-500 μg/mL) in order to determine potential neuroprotective properties of the mushroom. A negative control of N2a cells was used to determine cell viability and a positive control of H2O2 was used to determine cell toxicity. Oven-dried aqueous extract of Calocybe indica showed the highest cell viability (121%), followed by oven-dried ethanol extract (113%), freeze-dried aqueous extract (112%), and freeze-dried ethanol extract (105%). Neuroprotection against H2O2 followed a similar trend. Lower concentrations of Calocbye indica correlated with higher cell viability and neuroprotection. The total phenolic content and antioxidant activity of the mushroom were evaluated using a Folin-Ciocalteu reagent and 2,2-diphenyl-1- picrylhydrazyl (DPPH) dye.Oven-dried ethanol extracts showed the highest neuroprotective effects, the second highest total phenolic content (5.04 mg GAE/50 g dried mushroom weight), and the third highest antioxidant activity (12.89 mg/mL). Freeze-dried ethanol extracts showed the highest total phenolic content (7.2 mg GAE/50 g dried mushroom weight) and the highest antioxidant activity (EC50=8.63 mg/mL) despite having the lowest neuroprotective effects. A moderate positive correlation (R2 = 0.61) was found between total phenolic content and antioxidant activity. While phenolic content plays a considerable role in antioxidant activity, there is reasonable evidence that non-phenolic compounds contribute greatly to antioxidant activity and neuroprotection