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  1. Saari NF, Putra A, Irianto, Dan RM, Zeli MA, Ramlan R, et al.
    Heliyon, 2024 Feb 29;10(4):e26148.
    PMID: 38390043 DOI: 10.1016/j.heliyon.2024.e26148
    Piping system is the main structure in many industrial applications, especially for large industry relating with processing and transporting fluids, such as oil and gas industries. The fluid-induced vibration is often the cause of structural fatigue in pipes and therefore piping vibration need to be closely monitored. In case of high piping vibration, knowledge of the natural frequency of a pipe section is crucial for an engineer to propose the right troubleshoot action, either for a temporary or even for a long-term solution for the piping vibration. Therefore, prediction of the pipe natural frequency using a simple formulae is thus of interest, without dealing with complex numerical simulation using a commercial software which consumes cost and time. In this paper, the vibration mode shapes of various possible geometries of pipes in practice were simulated in ANSYS and the simulated natural frequency is related to a natural frequency of an Euler-Bernoulli beam using a correction factor for each corresponding piping geometry. This paper extends the previous work by allowing the boundary conditions of the pipe ends to be simply supported, in addition to the clamped edges. In this way, the frequency factor charts are presented in the range of possible correction factor values to accommodate the real conditions of pipe arrangement in practical application. An experiment from a case study to verify the proposed method is also presented.
  2. Handayani D, Aminah I, Pontana Putra P, Eka Putra A, Arbain D, Satriawan H, et al.
    Saudi Pharm J, 2023 Sep;31(9):101744.
    PMID: 37649676 DOI: 10.1016/j.jsps.2023.101744
    Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging nosocomial pathogen among hospitalized patients, with high morbidity and mortality rates. The discovery of a novel antibacterial is urgently needed to address this resistance problem. The present study aims to explore the antibacterial potential of three depsidone compounds: 2-clorounguinol (1), unguinol (2), and nidulin (3), isolated from the marine sponge-derived fungus Aspergillus unguis IB1, both in vitro and in silico. The antibacterial activity of all compounds was evaluated by calculating the Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) against MRSA using agar diffusion and total plate count methods, respectively. Bacterial cell morphology changes were  studied for the first time using scanning electron microscopy (SEM). Molecular docking, pharmacokinetics analysis, and molecular dynamics simulation were performed to determine possible protein-ligand interactions and the stability of the targeting penicillin-binding protein 2a (PBP2a) against 2-clorounguinol (1). The research findings indicated that compounds 1 to 3 exhibited MIC and MBC values of 2 µg/mL and 16 µg/mL against MRSA, respectively. MRSA cells displayed a distinct shape after the addition of the depsidone compound, as observed in SEM. According to the in silico study, 2-chlorounguinol exhibited the highest binding-free energy (BFE) with PBP2a (-6.7 kcal/mol). For comparison, (E)-3-(2-(4-cyanostyryl)-4-oxoquinazolin-3(4H)-yl) benzoic acid inhibits PBP2a with a BFE less than -6.6 kcal/mol. Based on the Lipinski's rule of 5, depsidone compounds constitute a class of compounds with good pharmacokinetic properties, being easily absorbed and permeable. These findings suggest that 2-chlorounguinol possesses potential antibacterial activity and could be developed as an antibiotic adjuvant to reduce antimicrobial resistance.
  3. Salim, M. A., Wan Mohamad, W. M. F., Maksom, Z., Kamat, S. R., Sukarma, L., Putra, A., et al.
    MyJurnal
    This paper presents the housing improvement proposition in the Melaka resident area.Quality Function Deployment is used as a method to analyze customer behavior regarding customer requirement, satisfaction and comparison among the developers. By using this method, the main requirement by the buyer for their bungalow is their need of sufficient space to place their appliances in the house. At the end of the study, the details of buyer requirements are plotted into House of Quality, where it is believed to improve the quality of future bungalow house development in Melaka.
  4. Putra A, Saari NF, Bakri H, Ramlan R, Dan RM
    ScientificWorldJournal, 2013;2013:742853.
    PMID: 24324380 DOI: 10.1155/2013/742853
    A laboratory-based experiment procedure of reception plate method for structure-borne sound source characterisation is reported in this paper. The method uses the assumption that the input power from the source installed on the plate is equal to the power dissipated by the plate. In this experiment, rectangular plates having high and low mobility relative to that of the source were used as the reception plates and a small electric fan motor was acting as the structure-borne source. The data representing the source characteristics, namely, the free velocity and the source mobility, were obtained and compared with those from direct measurement. Assumptions and constraints employing this method are discussed.
  5. Herawan SG, Ahmad MA, Putra A, Yusof AA
    ScientificWorldJournal, 2013;2013:545948.
    PMID: 24027443 DOI: 10.1155/2013/545948
    Activated carbons are regularly used the treatment of dye wastewater. They can be produced from various organics materials having high level of carbon content. In this study, a novel Pinang frond activated carbon (PFAC) was produced at various CO₂ flow rates in the range of 150-600 mL/min at activation temperature of 800°C for 3 hours. The optimum PFAC sample is found on CO₂ flow rate of 300 mL/min which gives the highest BET surface area and pore volume of 958 m²/g and 0.5469 mL/g, respectively. This sample shows well-developed pore structure with high fixed carbon content of 79.74%. The removal of methylene blue (MB) by 95.8% for initial MB concentration of 50 mg/L and 72.6% for 500 mg/L is achieved via this sample. The PFAC is thus identified to be a suitable adsorbent for removing MB from aqueous solution.
  6. Herawan SG, Hadi MS, Ayob MR, Putra A
    ScientificWorldJournal, 2013;2013:624865.
    PMID: 23737721 DOI: 10.1155/2013/624865
    Activated carbons can be produced from different precursors, including coals of different ranks, and lignocellulosic materials, by physical or chemical activation processes. The objective of this paper is to characterize oil-palm shells, as a biomass byproduct from palm-oil mills which were converted into activated carbons by nitrogen pyrolysis followed by CO2 activation. The effects of no holding peak pyrolysis temperature on the physical characteristics of the activated carbons are studied. The BET surface area of the activated carbon is investigated using N2 adsorption at 77 K with selected temperatures of 500, 600, and 700°C. These pyrolysis conditions for preparing the activated carbons are found to yield higher BET surface area at a pyrolysis temperature of 700°C compared to selected commercial activated carbon. The activated carbons thus result in well-developed porosities and predominantly microporosities. By using this activation method, significant improvement can be obtained in the surface characteristics of the activated carbons. Thus this study shows that the preparation time can be shortened while better results of activated carbon can be produced.
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