19672 research outputs found
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Natural gas industry transformation in Peninsular Malaysia: The journey towards a liberalised market
No full textMalaysia's gas industry has been undergoing a profound transformation that is imperative in ensuring energy security. The rising demand especially in Peninsular Malaysia and regulating prices of natural gas saw PETRONAS selling natural gas at a relatively low price that affects the Government's revenue collection negatively. This article contextualised the changes in the law and policy that concerns the management of gas resources in Malaysia. The journey from a price regulated gas market towards a liberalised market is explained. This energy transition process requires more than changes in the law. It involves the synergy of dynamics from various aspects to ensure that the ecosystem is conducive for the development of a healthy natural gas sector to ensure secured energy supply, while catalysing the growth of new industries and generating new revenues for the nation. The challenges and pushbacks throughout this journey are highlighted. Discussions show how the problems were tackled strategically within the political, social and economic domains, as well as the interaction between them. These interactions demonstrate the importance of energy justice in policy making. Policy decisions are made to balance the competing goals of various key stakeholders
Segmentation of left ventricle in late gadolinium enhanced MRI through 2D‐4D registration for infarct localization in 3D patient‐specific left ventricular model
No full textPurpose: To evaluate a 2D-4D registration-cum-segmentation framework for the delineation of left ventricle (LV) in late gadolinium enhanced (LGE) MRI and for the localization of infarcts in patient-specific 3D LV models. Methods: A 3-step framework was proposed, consisting of: (1) 3D LV model reconstruction from motion-corrected 4D cine-MRI; (2) Registration of 2D LGE-MRI with 4D cine-MRI; (3) LV contour extraction from the intersection of LGE slices with the LV model. The framework was evaluated against cardiac MRI data from 27 patients scanned within 6 months after acute myocardial infarction. We compared the use of local Pearson's correlation (LPC) and normalized mutual information (NMI) as similarity measures for the registration. The use of 2 and 6 long-axis (LA) cine-MRI scans was also compared. The accuracy of the framework was evaluated using manual segmentation, and the interobserver variability of the scar volume derived from the segmented LV was determined using Bland-Altman analysis. Results: LPC outperformed NMI as a similarity measure for the proposed framework using 6 LA scans, with Hausdorrf distance (HD) of 1.19 ± 0.53 mm versus 1.51 ± 2.01 mm (endocardial) and 1.21 ± 0.48 mm versus 1.46 ± 1.78 mm (epicardial), respectively. Segmentation using 2 LA scans was comparable to 6 LA scans with a HD of 1.23 ± 0.70 mm (endocardial) and 1.25 ± 0.74 mm (epicardial). The framework yielded a lower interobserver variability in scar volumes compared with manual segmentation. Conclusion: The framework showed high accuracy and robustness in delineating LV in LGE-MRI and allowed for bidirectional mapping of information between LGE- and cine-MRI scans, crucial in personalized model studies for treatment planning
Characterization of quorum sensing genes and N-acyl homoserine lactones in Citrobacter amalonaticus strain YG6
No full textIn the phylum of Proteobacteria, quorum sensing (QS) system is widely driven by synthesis and response of N-acyl homoserine lactone (AHL) signalling molecules. AHL is synthesized by LuxI homologue and sensed by LuxR homologue. Once the AHL concentration achieves a threshold level, it triggers the regulation of target genes. In this study, QS activity of Citrobacter amalonaticus strain YG6 which was isolated from clams was investigated. In order to characterise luxI/R homologues, the genome of C. amalonaticus strain YG6 (4.95 Mbp in size) was sequenced using Illumina MiSeq sequencer. Through in silico analysis, a pair of canonical luxI/R homologues and an orphan luxR homologue were identified and designated as camI, camR, and camR2, respectively. A putative lux box was identified at the upstream of camI. The camI gene was cloned and overexpressed in E. coli BL21 (DE3)pLysS. High-resolution triple quadrupole liquid chromatography mass spectrometry (LC-MS/MS) analysis verified that the CamI is a functional AHL synthase which produced multiple AHL species, namely N‑butyryl‑L‑homoserine lactone (C4-HSL), N‑hexanoyl‑L‑homoserine lactone (C6-HSL), N‑octanoyl‑L‑homoserine lactone (C8-HSL), N‑tetradecanoyl‑L‑homoserine lactone (C14-HSL) and N‑hexadecanoyl‑L‑homoserine lactone (C16-HSL) in C. amalonaticus strain YG6 and camI gene in recombinant E. coli BL21(DE3)pLysS. To our best knowledge, this is the first functional study report of camI as well as the first report describing the production of C14-HSL by C. amalonaticus
Elevated concentration of radioactive potassium in edible algae cultivated in Malaysian seas and estimation of ingestion dose to humans
No full textAlthough the various benefits of seaweeds are well recognised, potential health hazards are much less well researched, as an instance the possible presence of concentrated levels of natural radionuclides. In present work the concentrations of natural radionuclides in seaweed cultivated in Malaysian seas are assessed using conventional HPGe γ-ray spectrometry. An edible species of seaweed has been collected from several seaweed farms located along coasts of the Andaman and South China Sea. Activity concentrations of 226Ra, 228Ra and 40K in samples collected from Langkawi are observed to be greater than those from Sabah, while 40K radioactivity levels (2.2E3 ± 100 – 3.8E3 ± 180 Bq kg−1) in all samples are noted to be well above the world average value of between 400 and 580 Bq kg−1. The estimated amount of total potassium is in the range 68 – 120 g (kg of seaweed)−1 and 53–106 g kg−1 obtained via ICP-OES, which are in line with data for New Zealand seaweed of between 43.7 and 123 g kg−1. The estimated total effective dose of 84 μSv·y−1 is lower compared to a global internal dose of 290 μSv·y−1 as reported by UNSCEAR. Accordingly, the mean cancer risk from such consumption was also estimated to be slightly lower (1.92 × 10−3) compared to the ICRP cancer risk factor of 2.5 × 10−3 based on the additional annual dose limit of 1 mSv for a member of the general public, which gives an annual mortality probability of 10−5 (1 in 100,000; ICRP, 1991). Although posing a low risk health hazard, periodic monitoring of natural radioactivity in foodstuff remains important in seeking to ensure the radiological safety of the public
Isolation of antioxidative compounds from Micromelum minutum guided by preparative thin layer chromatography-2,2-diphenyl-1-picrylhydrazyl (PTLC-DPPH) bioautography method
No full textThe application of preparative thin layer chromatography-2,2-diphenyl-1-picrylhydrazyl (PTLC-DPPH) bioautography technique successfully isolated a lignan sesamin (1), two prenylated coumarins (2 and 3) and a marmesin glycosides (4) from Micromelum minutum methanol bark extract. Compounds 2 and 3 were identified as new compounds whereas 1 and 4 were first isolated from Micromelum genus. Structural identification of all compounds were done by detailed spectroscopic analyses and comparison with literature data. Antioxidant capacities of extract, active fraction and compounds were measured based on DPPH free radical savenging activity, oxygen radical absorbance capacity (ORAC) and β-carotene bleaching. The DPPH activity of methanol extract and its fraction present the IC50 values of 54.3 and 168.9 µg/mL meanwhile the β-carotene bleaching results were 55.19% and 5.75% respectively. The ORAC measurements of M. minutum extract, compounds 2 and 4 showed potent antioxidant activity with the values of 5123, 5539 and 4031 µmol TE/g respectively
The relationship of safety climate factors, decision making attitude, risk control, and risk estimate in Malaysian radiation facilities
No full textSafety culture practices tend to strongly influence workers to control possible risk, make decision, and have a true perception on the risk despite the aim of encouraging safe work environment and reducing the numbers of human errors. The present study assessed the perceptions of the workers on nine safety culture practices as well as the individual risk estimate on the chemical and radiation hazard. In this study, a questionnaire survey was conducted among the workers of nuclear and radiation facilities in Malaysia. In this study, structural equation modelling (SEM) was utilised to analyse the relationship between the variables. The reliability and validity of the measured item was found to be acceptable. Meanwhile, the significant direct path of safety climate factors managed to be shown together with risk control measures, decision making attitude, and individual risk estimate. However, risk control measure and decision-making attitude did not mediate the relationship between safety climate factors and the risk estimate. On the other hand, priority to safety was identified as the most important factor that affects risk estimate, risk control measure, and decision-making attitude. This study also emphasized the requirement of communicative information which can be performed through information sharing, dissemination, and questioning mechanism. Overall, these findings manage to facilitate radiation stakeholders in developing the framework of safety culture practices as well as strengthening the safety management system
Cycloartane triterpenoid (23R, 24E)-23-acetoxymangiferonic acid inhibited proliferation and migration in B16-F10 melanoma via MITF downregulation caused by inhibition of both β-catenin and c-Raf–MEK1–ERK signaling axis
No full textWe recently reported that (23R, 24E)-23-acetoxymangiferonic acid (23R-AMA), a cycloartane triterpenoid isolated by activity-guided separation from a methanol extract of Garcinia sp. bark, inhibited melanin production via inhibition of tyrosinase (TYR) expression in the B16-F10 melanoma cell line. Since 23R-AMA also inhibited microphthalmia-associated transcription factor (MITF) expression, an upstream factor of TYR, these features of 23R-AMA were thought to be appropriate for development of whitening cosmetics. However, 23R-AMA exhibited growth inhibition other than inhibition of melanin production in B16-F10 cells. Therefore, we investigated biological activities of 23R-AMA in detail, focused on its application as an anti-melanoma compound. In this study, we demonstrated that 23R-AMA inhibited cell proliferation and basic FGF (bFGF)-induced migration in B16-F10 cells. Furthermore, 23R-AMA promoted ser45/thr41 phosphorylation of β-catenin and suppressed its intranuclear accumulation, which was suggested to be related to inhibition of MITF expression. The transcriptional activity of MITF is known to be regulated by phosphorylation via activated ERK. Further investigation revealed that 23R-AMA inhibited phosphorylation of c-Raf, MEK-1, and ERK, and also that of upstream molecules including FAK and c-Src. These results suggested that 23R-AMA inhibited growth and migration of B16-F10 melanoma by regulating both MITF expression and its activity. The activities of 23R-AMA reported in this study are new aspects of cycloartane triterpenoids
Approaches for preserving content integrity of sensitive online Arabic content: A survey and research challenges
No full textTrends in Internet usage and accessing online content in different languages and formats are proliferating at a considerable speed. There is a vast amount of digital online content available in different formats that are sensitive in nature with respect to writing styles and arrangement of diacritics. However, research done in the area aimed at identifying the necessary techniques suitable for preserving content integrity of sensitive digital online content is limited. So, it is a challenge to determine the techniques most suitable for different formats such as image or binary. Hence, preserving and verifying sensitive content constitutes an emerging problem and calls for timely solutions. The digital Holy Qur'an in Arabic, constitutes, one case of such sensitive content. Due to the different characteristics of the Arabic letters like diacritics (punctuation symbols), kashidas (extended letters) and other symbols, it is very easy to alter the original meaning of the text by simply changing the arrangement of diacritics. This article surveys the different approaches that are presently employed in the process of preserving and verifying the content integrity of sensitive online content. We present the state-of-the-art in content integrity verification and address the existing challenges in preserving the integrity of sensitive texts using the Digital Qur'an as a case study. The proposed taxonomy provides an effective classification and analysis of existing related schemes and their limitations. The paper discusses the recommendations of the expected efficiency of such approaches when applied for use in digital content integrity. Some of the main findings suggest unified approaches of watermarking and string matching approaches can be used to preserve content integrity of any sensitive digital content
Tribological behaviour of the double FeCoNiCrCux middle-entropy alloy coatings
No full textIn the present research, the double FeCoCrNiCux medium-entropy alloy coatings were manufactured on Cr12MoV die steel by laser cladding technology. The cross-section, microstructure, phase, micro-hardness, and tribological behaviour of the coatings were investigated systemically. The dilution effect of the substrate had the weaker effect on the second layer compared to the first layer. The double FeCoCrNiCux cladding layers only had a single face-centred cubic phase led to the lower micro-hardness and wear resistance. The different atomic radius of the alloying elements in the coatings generated a large lattice dislocation. The face-centred cubic structure of coatings had a higher hardness than that of the traditional face-centred cubic structure. The Cu element is easy to segregate at the grain boundaries to form the Cu-rich solid solution
Pretreated aluminium dross waste as a source of inexpensive alumina-spinel composite ceramic hollow fibre membrane for pretreatment of oily saline produced water
No full textPretreatment of produced water using ceramic membrane is considered promising due to its excellent separation performance and thermal and mechanical stabilities, however, the high cost of ceramic membranes discourages industries for large scale applications. The purpose of this work is to fabricate ceramic hollow fibre membranes from alumina-spinel composite powder synthesized from low-cost aluminium dross waste for the pretreatment of oily saline produced water. The hollow fibre membranes were prepared via phase inversion-based extrusion and sintering technique. Aluminium dross (less than 50 µm) was subjected to pre-treatment via water leaching and calcination, resulting in alumina (Al2O3) and spinel (MgAl2O4) as major constituents. Subsequently, the as-prepared alumina-spinel composite powder was used as a ceramic material in fabricating the hollow fibres. The effect of sintering temperatures on the morphology, crystalline phase, pore size and porosity, mechanical properties, and removal efficiencies of the alumina-spinel composite hollow fibre membranes were investigated. The microfiltration test of the hollow fibres was assessed using produced-water feed of 200 mg L−1 at 1 bar. The hollow fibre sintered at 1275 °C offers 92.41% rejection percentage of oil, the highest after 50 min of stable flux. Furthermore, turbidity was found to decrease from 378 NTU to 28.5 and 22.5 NTU for hollow fibres sintered at 1250 and 1275 °C after 2 h of filtration. In this work, the alumina-spinel composite hollow fibre membranes are found to be an effective tool as an alternative for the pretreatment of oily saline produced water