ORCID Profile
0000-0003-3146-9517
Current Organisation
Universitas Brawijaya
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Publisher: Hindawi Limited
Date: 2016
DOI: 10.1155/2016/9240416
Abstract: Palm fibers were immersed in sea water for 1, 2, 3, and 4 weeks prior to application as reinforcement of green biocomposite. Instead of common resin matrix, natural sago starch was applied as the matrix compound. The immersion treatments had significantly affected fibers surface morphology and interfacial bonds of fiber and the matrix as observed through Scanning Electron Microscopy (SEM). The quality of interfacial bonds became higher by additional duration of the sea water immersion. The best interlocking surfaces of fibers and matrix appeared in the composite with 4-week immersed fibers, indicated by disappearance of gaps between fiber and matrix. The morphology of fibers surface interlocking process was clearly seen during the duration of immersion.
Publisher: Private Company Technology Center
Date: 29-10-2022
DOI: 10.15587/1729-4061.2022.266012
Abstract: The balance of dissolved oxygen and pH levels is paramount in aquaculture, as a media for cultivating aquatic organisms under controlled conditions. An imbalance in both oxygen and pH could severely harm the cultured aquatic organisms. Various strategies are used to prevent hypoxia and maintain the pH level of the culture. Interestingly, hypoxia or deprivation of oxygen supply in aquaculture was often reported to co-occur with the seawater acidification. Despite that, there was no evidence that the O2 level was directly linked to pH changes. Thus, the existing treatment strategies are separated between O2 and pH maintenances, which often inflate cost and cause environmental burden due to the use of synthetic chemicals. This study was conducted to observe the mechanism and effect of the O2 addition to aquaculture seawater in molecular level when the pH value of the water was modified. The understanding of the mechanism may lead to an alternative to the harmful aquaculture treatments. The molecular mechanics analysis was applied to examine the mechanism of pH adjustment in non-aerated and aerated seawater. The results indicated that O2 accelerated the pH recalibration of seawater, particularly in the alkaline modified s les compared to the acid modified s les. Mechanical simulations further showed the repulsion between and O2 causes vibration which shortens OH bond by 17.71 % while elongates O-O bond by 1.00 %. Additionally, the spin coupling between OH- and O2 promotes global energy transfer which stimulates the vibration of the alkaline modified water system. Together, those mechanisms enabled the pH value to return to the baseline. These findings contribute a molecular mechanism view of aquaculture pH maintenance in the presence of O2, as well as revisiting the use of aeration in aquaculture treatment
Publisher: Private Company Technology Center
Date: 31-08-2020
Publisher: Trans Tech Publications, Ltd.
Date: 12-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.724.39
Abstract: Effects of sea water immersion for palm fiber in relation to surface morphology, roughness and bonding between the fiber and sago matrix were observed. Duration of immersion varied in 1, 2, 3 and 4 weeks, and then dried at room temperature for 3 hours continued by oven at 80 °C for 6 hours. SEM and roughness arithmetic tests were applied to see surface morphology, roughness and bonding between fiber and the matrix. Result shows fiber morphology and roughness varies by the duration of immersion. The surface roughness increases as immersion continues along with fiber - matrix bonding improvement. The maximum duration of 4 weeks fiber immersion resulted in the best interlocking of matrix and fibers, as the slits between them disappear.
Publisher: Index Copernicus
Date: 09-2020
DOI: 10.5604/01.3001.0014.5119
Abstract: Purpose: To find out more about the role of hydrogen gas bubbles in improving the hydrophobic nature of a layer, especially in the layers of microparticles Alumina (Al2O3) with Magnesium (Mg). Design/methodology/approach: The method used is an experimental method by first conducting the SEM-Edx test, testing the content of the elements in the waxy layer and observing the topographic shape on the surface of the taro leaves. Then prepare a mixture of Alumina micro particles with Magnesium to investigate the hydrophobicity of the taro leaves. The mixed presentations between Alumina and Magnesium are: (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%). Findings: The results of this study found three conditions of the Alumina and Magnesium mix layer when in contact with a droplet, namely: Hydrophobic conditions occur when the surface structure of the rough mixed micro layer forms micro crevices, then bubbles of hydrogen gas fill it to form trapped gases. When droplets come in contact with the surface of the mixed layer the effect of the gas being trapped is very effective at creating hydrophobic properties. While the transition conditions occur when more and more hydrogen gas bubbles along with the increasing percentage of Mg and the opposite occurs in micro particle fissures. Bubbles fill the micro-gap space fully so that the tops of the micro particles are covered by bubbles. This causes the droplet surface tension to weaken, so the droplet contact angle decreases. Furthermore, hydrophilic conditions occur when the micro gap is getting narrower as the percentage of Mg increases and the formation of hydrogen gas bubbles increases. The high level of bubble density in the micro gap closes the peaks of the micro particles, which results in the surface tension of the droplet getting weaker. In this weak surface tension condition, the hydrogen bubble can break through the droplet surface tension and change its hydrophobic nature to hydrophilic. Research limitations/implications: This research is limited to the hydrophobicity of Alumina and Magnesium materials, mainly to investigate the role of hydrogen gas in supporting the hydrophobic nature of taro leaves (Colocasia esculenta). Practical implications: The practical implication in this study is the use of hydrophobic membranes which are widely applied to filtration. Originality/value: Discovered the composition of a membrane mixture of Alumina (Al2O3) and Magnesium (Mg) to create hydrophilic and hydrophobic conditions.
Publisher: Hindawi Limited
Date: 29-07-2021
DOI: 10.1155/2021/8827427
Abstract: The direct use of vegetable oil is constrained by vegetable oils’ viscosity, which is relatively high. Therefore, this study discusses reducing the vegetable oils viscosity molecularly, using natural additives of Areca extract. The role of Areca extract on diminishing the viscosity of vegetable oil was simulated utilizing HyperChem software. Then, the viscosity was verified using the ASTM D445 method. The results show that the epicatechin in the Areca extract generates a local magnetic field on its aromatic ring that plays the role of energizing electron mobility in vegetable oil. On the one hand, increased electron mobility decreases oil polarity but, on the other hand, increases the London force via a temporary dipole charge. Simultaneously, it relaxes oil molecules that tend to increase molecule distance decreasing the London force. Since viscosity is proportional to the London force and oil polarity thus, these three phenomena determine the role of Areca extract on the oil viscosity. The viscosity reduction is smaller at a larger number of the double bonds in the fatty acid chain since the local magnetic field’s induction on the electron spin is interrupted in the double bonds
Publisher: Private Company Technology Center
Date: 30-06-2020
Publisher: Hindawi Limited
Date: 12-01-2022
DOI: 10.1002/ER.7638
Publisher: Private Company Technology Center
Date: 30-06-2023
DOI: 10.15587/1729-4061.2023.279099
Abstract: High sulfate content in seawater forms sulfate salts, which become impurities in sea salts. This study investigates the influence of lime juice in the adsorption of sulfate ions in seawater using commercial activated carbon. A full factorial experimental design was employed to optimize the level factors of activated carbon type, adsorbent dosage, and concentration of lime juice in response to the percentage reduction in sulfate concentration. Activated carbon (GCB) and acid-washed activated carbon (GCA) were two types of coconut shells granular activated carbon used for the experiment without further modification. The main effect and interaction effects were analyzed using analysis of variance (ANOVA) and p-values to define the influence of variables affecting sulfate ions adsorption. The adsorption of sulfate ions in seawater was affected by the interaction between the activated carbon type and the dosage, and the concentration of lime juice. The lime juice factor significantly enhanced the performance of activated carbon to adsorb the sulfate ions in seawater, and the factor's contribution was 58.2 %. The optimum sulfate ions reduction from seawater was attained at levels of factors activated carbon GCB, the dosage of 50mg, and the concentration of lime juice 50 µl. The interaction between lime juice and activated carbon pores are electrostatic. The impurities are attracted by the revealed polarity of the activated carbon pores. High electronegativity of lime juice acid pulls the negatively charged ions of the impurities. The more economical activated carbon, GCB, which performed better in sulfate ion adsorption, provides an alternative for reducing sea salt impurities. Hence, GCB can directly be mixed with the seawater to produce high quality sea-salt. Therefore, this study is suitable to improve sea salt product quality that processed with activated carbon
Publisher: Praise Worthy Prize
Date: 28-02-2017
Publisher: Elsevier BV
Date: 08-2023
No related grants have been discovered for I Nyoman Gede Wardana.