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Acrylated Epoxidized Soybean Oil as a Green Alternative Healant in Development of Autonomous Self-Healing Materials
No full textProgresses in the development of self-healing materials have resulted in transition from repairing damaged materials via external interference to autonomous internal healing process. This paper explores reaction between acrylated expoxidized soybean oil (AESO) with pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) hardener, followed by microencapsulation of AESO for its potential use in a novel self-healing system. Self-healing reaction involving AESO and PETMP is considered more environmentally friendly than most of the reported self-healing reactions not only because AESO is derived from renewable resources, but also due to the fact that the reaction does not rely on any heavy metal catalyst. Such catalysts are usually introduced in a self-healing system to speed up the intended healing process and it could be very harmful to the environment and also to the end users. It was found that AESO and PETMP are able to crosslink with each other and solidify at room temperature within 15 min of mixing. The reaction occurs readily at room temperature without any external interference, suggesting the viability of the reaction to be utilized in an autonomous self-healing system. This paper follows through with microencapsulation of AESO in melamine-urea-formaldehyde, and result of the characterizations reveal that the microcapsules obtained are spherical with average diameter of around 150 µm, free-flowing, thermally stable at temperature up to 200 °C, and the calculated % of microencapsulation reached as high as 86.4%. © 2018, Springer Science+Business Media, LLC, part of Springer Nature
Extractive separation of benzene and cyclohexane using binary mixtures of ionic liquids
No full textThe separation of benzene and cyclohexane is a challenging process in petrochemical industry due to their close boiling points. Solvent mixing is a useful technique to enhance the extraction performance of liquid–liquid extraction process. In this work, the performance of solvent mixtures involving two organic solvents (N,N-dimethylformamide and ethylene glycol) and four ionic liquids (ILs), namely, 1-ethyl-3-methylimidazolium thiocyanate (C2mimSCN), 1-ethyl-3-methylimidazolium dicyanamide (C2mimN(CN)2), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C2mimTf2N) and 1-ethyl-3-methylimidazolium acetate (C2mimAc) was investigated for the extractive separation of benzene and cyclohexane. The mixing ratios of the binary solvents were optimized using the ideal mixing calculation and validated experimentally through liquid–liquid extraction process. Six new quaternary liquid–liquid equilibria for the mixed solvents with benzene and cyclohexane were investigated at 25 °C and 1 atm, with feed concentrations of benzene ranging from 10 to 50 wt%. Ethylene glycol was discovered a good solvent pair with C2mimTf2N that could lead to potential cost savings. At the optimized mixing fraction, the {C2mimTf2N + C2mimSCN} mixture demonstrated the highest extraction performance, which was superior to that of sulfolane. Additionally, the {C2mimSCN + C2mimN(CN)2} and {C2mimN(CN)2 + C2mimAc} mixtures were found to increase the selectivity while maintaining the benzene distribution ratio in relation to sulfolane. The ILs were not present in the raffinate layer of any of the systems, indicating the reliable performance of the ILs in terms of avoiding solvent cross-contamination. This work demonstrated the use of binary solvent mixtures as a new efficient and versatile method to enhance extraction performance. © 2019 Elsevier B.V
In-vitro cytotoxicity of Trigona itama honey against human lung adenocarcinoma epithelial cell line (A549)
No full textIntroduction: Many efforts have been made to identify natural alternatives to reduce the side effects of cytotoxic drugs in cancer treatment. With this in mind, the current study aimed to investigate the cytotoxicity effects of one of the multifloral Malaysian honey, Kelulut honey (Trigona itama), as a potential natural anticancer agent in stimulating apoptosis and cell cycle arrest to a human lung adenocarcinoma epithelial cell line (A549). Methods: The cells were treated with various concentrations of T. itama honey for 24, 48 and 72 h. The cytotoxicity and cell viability were determined using trypan blue exclusion assay (TBEA) and flow cytometric analysis. Results: The moisture content in the analysed honey was 14.3 ± 0.8%, which was within the accepted international standard. The pH, electrical conductivity and proline content were 3.17 ± 0.02, 0.47 mS/cm - 0.55 mS/cm and 19.1 mg/kg 20.2 mg/kg respectively. The findings demonstrated a significant dose and time-dependent inhibitory effect of T. itama honey with the maximum cytotoxic effects observed at 72 h with 20% concentration of T. itama honey, indicating 100% growth inhibition. Meanwhile, IC50 of T. itama honey treatment for A549 cells was determined as 0.62% v/v. Moreover, T. itama honey had a promising cytotoxic effect and proven capable of inducing cell cycle arrest at G2/M phase at 72 h of exposure with IC50 concentration. Conclusion: This study provided prefatory evidence on T. itama honey's significant anticancer activity against human lung cancer cell lines. © 2019 Elsevier Gmb
Detection of Somaclonal Variation in Micropropagated and Acclimatized Plantlets of Oryza sativa MRQ 74 from Stem Explants
No full textIn plant tissue culture system, the excessive supply of plant growth hormones may inhibit further growth and development of the regenerants and sometimes it may induce somaclonal variation. In this study, the optimum concentration of plant growth hormones for in vitro regeneration of Oryza sativa L. cv. MRQ 74 was identified and subsequently the occurrence of somaclonal variation of regenerated plantlets was determined through cytological analysis of in vivo and in vitro grown plantlets. MS media supplemented with 0.1 mg L-1 BAP in combination with 0.1 mg L -1 NAA was found to be the optimum concentration for shoots and roots induction of Oryza sativa L. cv. MRQ 74. Plantlets derived from MS media supplemented with 0.5 mg L -1 2,4-D showed higher survival rate than that of MS media supplemented with 0.1 mg L -1 BAP in combination with 0.1 mg L -1 NAA. The plant height, number of leaf, leaf length and number of seeds per stalk of acclimatized plants were significantly lower (p<0.05) as compared with plants grown in vivo. Cytological analysis of in vivo and in vitro grown Oryza sativa L. cv. MRQ 74 revealed that the presence of 2,4-D in the culture media had significantly decreased the mitotic index (MI) and increased the ploidy level of the cell nuclei. The findings of the present study would be useful for plant breeders and biotechnologist since somaclonal variation provides a useful source of genetic variation for crop productivity and quality improvement. © 2019, Sociedade Brasileira da Ciencia das Plantas Daninha. All rights reserved
FIrpic thin film as saturable absorber for passively Q-switched and mode-locked erbium-doped fiber laser
No full textIn this paper, we demonstrate the generation of passive all-fiber Q-switched and mode locked erbium doped fiber lasers (EDFLs) by using Bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato) iridium(III) (FIrpic) as a saturable absorber (SA). The material was prepared by solvent-casting technique and inserted between two fiber ferrules to form an SA. Then it was placed in an EDFL cavity. A stable Q-switched pulse laser operating at 1560.4 nm was achieved at a threshold pump power of 30 mW. The pulse repetition rate increased from 39.22 to 87.4 kHz and the pulse width decreased from 9.5 to 3.4 µs as the pump power was gradually increased from 30 to 208 mW. Meanwhile, a soliton self-starting mode-locking pulses at a wavelength of 1562.57 nm was achieved by adding an additional 52 m SMF to the EDFL cavity. The mode-locked laser had a repetition rate of 3.43 MHz and a pulse width of 120 ns within the pump power of 35–185 mW. The results suggest that FIrpic SA can be used to produce stable Q-switched and mode-locked fiber lasers at a low pump power. © 2019 Elsevier Inc
Application of an evolutionary algorithm-based ensemble model to job-shop scheduling
No full textIn this paper, a novel evolutionary algorithm is applied to tackle job-shop scheduling tasks in manufacturing environments. Specifically, a modified micro genetic algorithm (MmGA) is used as the building block to formulate an ensemble model to undertake multi-objective optimisation problems in job-shop scheduling. The MmGA ensemble is able to approximate the optimal solution under the Pareto optimality principle. To evaluate the effectiveness of the MmGA ensemble, a case study based on real requirements is conducted. The results positively indicate the effectiveness of the MmGA ensemble in undertaking job-shop scheduling problems. © 2017, Springer Science+Business Media New York
A new species of the simulium (Simulium) crocinum species-group (diptera: Simuliidae) from Vietnam
No full textA new black fly species, Simulium yukawai, is described on the basis of one female and its pupal exuviae from Vietnam. This new species is placed in the S. crocinum species-group of Simulium (Simulium) (Diptera: Simuliidae). It is characterized in the female by the paraproct covered with 48–50 distinct hairs on its ventral and lateral surfaces, and in the pupa by the frons and most of the thorax bare, gill with six dark filaments in three pairs closely arising from the base, of which the two outer filaments of the dorsal and middle pairs are much longer than other filaments, abdomen with distinct spine-combs on the dorsal surface of segments 7–9, and cocoon wall-pocket shaped, with a large anterolateral window on each side. Taxonomic notes are given to separate this new species from related species. This species is the fourth member of the S. crocinum species-group known from Vietnam. © 2019, Malaysian Society for Parasitology. All rights reserved
Improving stability of zinc nanoparticles in chitosan solution with a nanosecond pulsed laser
No full textA green method is presented to fabricate zinc nanoparticles using laser ablation synthesis in a natural polymer solution. The main aims are to reduce the zinc nanoparticles size and to increase their stability by using different ablation times in a chitosan solution as a natural polymer stabilizer. A Nd:YAG pulsed laser (532 nm) of energy 60 mJ/pulse, with a pulse duration of 10 ns was used to ablate a zinc plate immersed in chitosan solution from which the nanoparticles were produced. The average particle sizes as well as the volume fraction of the zinc nanoparticles in the solution were measured at 5, 10, 15, 30 min of ablation time. The results showed that the particle size decreased from 9.43 to 5.04 nm with spherical morphology and its volume fraction increased from 0.24 10-7 to 8.5 10-7 as the ablation time progressed from 5 to 30 min respectively. As a comparative study, a reasonable decrease was observed in the particle size for chitosan than distilled water. It was also noted that the stability and dispersion of zinc nanoparticles were much higher in the chitosan solution compared to water. In addition, the COSMO (conductor-like screening model) solvation model was used to compare the enthalpies of Zn-NPs in different media. Obtained results confirmed their stability was higher when merged in a natural polymer compared to water. © 2019 Astro Ltd
K-pop, Aspirasi Kemodenan dan Ketidakpatuhan Strategik dalam Kalangan Wanita Melayu (K-pop, Aspiration of Modernization and Strategical Non-compliance Among The Malay Women's Circle)
No full textThe popularity of K-pop among Malay women has been criticised by various parties because of its tendency to erode culture of the Malay community and violate Islamic values – two important elements in the Malaysian modernity project. For example, the participation of Malay women lamenting the death of popular K-pop artist Kim Jong-Hyun and the Korean artist group's controversial act-B1A4; embracing three tudung-clad Malay girls in Kuala Lumpur received criticism from the public and Islamic authorities. This situation has given rise to a polemic of K-pop that is considered contrary to the idea of modernity of Malaysia. Hence, this article argues that Malay women use K-pop as a platform to adapt and negotiate the aspirations of global modernity through the practice of strategic disobedience with a diverse view under personal capacity and as a member of the local fan groups. For example, this incident has earned the attention of the Department of Islamic Development Malaysia (JAKIM) and the Federal Territory Religious Department (JAWI), which consider that kind of behaviour as against the Islamic law and Malay values. This qualitative study uses thematic textual analysis approach and focuses on the diverse views and audience interpretations of K-pop in the form of comments that appear in social media such as Twitter and YouTube as well as two popular news portals – The Star and Free Malaysia Today (FMT). The findings will be analysed through two important themes – self-regulation and selected openness – and these will establish strategic disobedience as a concept to explain the popularity of K-pop and its consumption among young Malay women. © 2019, Universiti Kebangsaan Malaysia Press. All rights reserved
Optimal Scheduling of Plug-in Electric Vehicle Charging Including Time-of-Use Tariff to Minimize Cost and System Stress
No full textTechnological advancement, environmental concerns, and social factors have made plug-in electric vehicles (PEVs) popular and attractive vehicles. Such a trend has caused major impacts to electrical distribution systems in terms of effciency, stability, and reliability. Moreover, excessive power loss, severe voltage deviation, transformer overload, and system blackouts will happen if PEV charging activities are not coordinated well. This paper presents an optimal charging coordination method for a random arrival of PEVs in a residential distribution network with minimum power loss and voltage deviation. The method also incorporates capacitor switching and on-load tap changer adjustment for further improvement of the voltage profile. The meta-heuristic methods, binary particle swarm optimization (BPSO) and binary grey Wolf optimization (BGWO), are employed in this paper. The proposed method considers a time-of-use (ToU) electricity tariff such that PEV users will get more benefits. The random PEV arrival is considered based on the driving pattern of four different regions. To demonstrate the effectiveness of the proposed method, comprehensive analysis is conducted using a modified of IEEE 31 bus system with three different PEV penetrations. The results indicate a promising outcome in terms of cost and the distribution system stress minimization. © 2019 by the authors