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Makara Journal of Science
Published by Universitas Indonesia
ISSN : 23391995     EISSN : 23560851     DOI : https://doi.org/10.7454/mss
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Makara Journal of Science publishes original research or theoretical papers, notes, and minireviews on new knowledge and research or research applications on current issues in basic sciences, namely: Material Sciences (including: physics, biology, and chemistry); Biochemistry, Genetics, and Molecular Biology (including: microbiology, physiology, ecology, taxonomy and evolution); and Biotechnology.
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Articles 8 Documents
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Search results for , issue "Vol. 24, No. 4" : 8 Documents clear
Effect of Applied Pressure During Sintering on the Densification and Mechanical Properties of SiCf/SiC Composites Prepared by Electrophoretic Infiltration Noviyanto, Alfian
Makara Journal of Science Vol. 24, No. 4
Publisher : UI Scholars Hub

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Abstract

SiC-fiber-reinforced SiC matrix ceramic (SiCf/SiC) composites were successfully fabricated by electrophoretic infiltration and sintering at various applied pressures. The effect of applied pressure (i.e., 5, 10, and 20 MPa) was thoroughly examined, and applied pressure appears to influence the densification and mechanical properties of SiCf/SiC composites. The densities of SiCf/SiC composites prepared at applied pressure of 5, 10, and 20 MPa were 2.99, 3.10, and 3.16 g/cm3, respectively. All samples showed dense microstructures in their matrix areas; however, many closed pores were found with increasing pressure. Pressure induced densification in the fiber area, and 20 MPa was determined to be the minimum pressure required for adequate densification. The liquid phase in the matrix area was effectively maintained at a high applied pressure, which resulted in densification. However, the liquid phase redistributed to the matrix or near the matrix area at applied pressures of MPa, leading to pores in the fiber areas of these samples. The highest flexural strength of 262 ± 18 MPa for the SiCf/SiC composite was achieved at an applied pressure of 20 MPa. Meanwhile, the flexural strengths of the composites prepared at 5 and 10 MPa were 198 ± 41 and 238 ± 32 MPa, respectively.
Lipid Peroxidation Inhibition Activity of Sintrong (Crassocephalum crepidioi-des) Leaf Extract in Rats Consuming Arak Jembrana Widayanti, Ni Putu; Laksmita W, Ayu Saka; Apriyanthi, Desak Putu Risky Vidika; Arijana, I G K Nyoman
Makara Journal of Science Vol. 24, No. 4
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The present study was conducted to determine the antioxidant activity of sintrong (Crassocephalum crepidioides) leaf extract to inhibiting lipid peroxidation by decreased malondialdehyde (MDA) level in the blood plasma of rats consuming arak Jembrana. The process of making sintrong leaf extract used 96% ethanol with maceration techniques. In vivo testing used five groups: (1) a control group, (2) treatment with arak, (3) treatment with arak followed by extract at a dose of 37.5 mg/kgBW, (4) treatment with arak followed by extract at a dose of 50 mg/kgBW, and (5) treatment with arak followed by extract at a dose of 75 mg/kgBW. As much as 1 cc/day of arak was provided for seven days. The extract treatment at a dose of 37.5 mg/kgBW decreased the MDA level from 21.24 nmol/L to 16.33 nmol/L. Based on a Tukey’s Honestly Significant Difference (HSDa) test, this treatment was not significantly different from that of the control group (normal condition).
Effect of Surfactant Addition on the Dispersion and Antioxidant Performance of Pyrogallol in Biodiesel Yusri, Silvya; Nasikin, Mohammad; Sutanto, Hery
Makara Journal of Science Vol. 24, No. 4
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Biodiesel is one of the most feasible energy sources that can be used as a replacement for fossil fuel. Biodiesel has several advantages over conventional fuels because of its availability, renewability, and high combustion efficiency. However, biodiesel that contains unsaturated fatty acid methyl esters is prone to oxidation during the blending process and storage period. The complete oxidation reaction of biodiesel produces insoluble gums that could potentially plug the fuel engines. This reaction has become the main barrier for biodiesel to compete with other biofuels. Among several methods, the addition of antioxidants is the most cost-effective method to prevent the oxidation reaction in biodiesel. Pyrogallol (PY), which is one of the best antioxidant additives for biodiesel, was used in this research to evaluate its performance. However, the fact that PY is partially soluble in biodiesel is considered a problem in the application of PY as an antioxidant additive in biodiesel. In this research, three different surfactants were added to increase the dispersion and performance of PY in biodiesel. Dispersion test, acid number analysis, and iodine value analysis were performed to evaluate the effect of surfactant addition on the dispersion and antioxidant performance of PY in biodiesel. The surfactant glycerol monostearate showed the best result in increasing the dispersion of PY in biodiesel compared with sorbitan monooleate and polyglyceryl-4-isostearate (PG4IS). By contrast, the best performance of PY in preventing the oxidation of biodiesel was achieved with the addition of PG4IS.
Lemongrass (Cymbopogon citratus) Ethanolic Extract Exhibited Activities That Inhibit -glucosidase Enzymes and Postprandial Blood Glucose Elevation Gunawan Puteri, Maria Dewi Puspitasari Tirtaningtyas; Tjiptadi, Felicia Melissa; Hendra, Phebe; Santoso, Filiana; Udin, Zalinar; Artanti, Nina; Florence Ignatia, Florence Ignatia
Makara Journal of Science Vol. 24, No. 4
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Lemongrass is a common ingredient in Indonesian traditional herbal medicine that potently inhibits carbohydrate hydrolysis. In this study, the in vitro α-glucosidase inhibitory (AGI) activity of lemongrass was compared with its in vivo activity to retard postprandial blood glucose elevation, and the bioactive compounds responsible for these activities were observed. Both water and ethanolic extracts of lemongrass (WLG and ELG, respectively) were tested in vitro for its inhibition of the sucrose and maltose hydrolyzing activities of rat intestinal glucosidase. ELG was observed to exert higher inhibitory activities (Sucrase IC50 = 8.74 mg/mL; Maltase IC50 = 18.93 mg/mL) than WLG. ELG was evaluated for its in vivo activity to retard blood glucose elevation in mice after sucrose, maltose, and glucose consumption. ELG was also fractionated using activity-guided chromatography, followed by liquid chromatography–mass spectrometry and high-performance liquid chromatography (HPLC). In vivo sugar tolerance test confirmed the AGI activity in a non-dose-dependent manner and showed potential additional mechanisms that may prevent postprandial hyperglycemia. The active principles were acquired in methanol-soluble fraction and purified using preparative thin-layer chromatography. HPLC analysis with commercial standards identified caffeic acid and kaempferol as the compounds responsible for the bioactivity of ELG. Results showed that lemongrass has the potential as herbal medicine ingredient in the management of diabetes.
DFT-based Study of Electric Field Effect on the Polarizability of Three Ringed Nematic Liquid Crystal Molecules Upadhyay, Pranav; Mishra, Mirtunjai; Trivedi, Ankur; Kumar, Jitendra; Kumar, Asheesh; Kumar, Devesh
Makara Journal of Science Vol. 24, No. 4
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Owing to its successful application to complex molecular systems, computational density functional theory (DFT) has been used to study the effect of an electric field on the molecular polarizability and HOMO–LUMO gap of 1-phenyl-4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}benzene (1) and its fluoro-, chloro-, and cyano- derivatives, namely, 1-fluoro-4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzene (2), 1-chloro-4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzene (3), and 4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzonitrile (4). These molecules belong to the family of nematic liquid crystals with three rings: two benzene and one cyclohexane. Furthermore, two DFT approaches, namely, B3LYP and M062X, have been used to examine the results obtained. This study reveals a remarkable feature: the polarizability of these molecules follows nearly a step function when varied with respect to the electric field. The 4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl)benzonitrile (4) polarizes more than all other derivatives, whereas 1-fluoro-4-(4-{2-[(1s,4r)-4-pentylcyclohexyl]ethyl}phenyl) benzene (2) has the widest stability region of them all. With the increase in the electric field, polarizability increases in a smooth manner until a point called here the shoot-up point at which polarizability switches to a higher value and remains nearly constant as the field increases further. However, beyond a certain value of the electric field, polarizability undergoes a steep fall. It is also found that the effective length (long molecular axis) of the molecule has a direct effect on its polarizability.
Efficient and Mild Four-component Process for the Synthesis of Highly Substituted Dihydro-2-oxopyrroles using ZrOCl2∙8H2O as an Environmental-ly Friendly Catalyst Mohamadpour, Farzaneh
Makara Journal of Science Vol. 24, No. 4
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This study investigated the catalytic ability of ZrOCl2∙8H2O as a mild, environmentally benign nature, and economical catalyst for the multi-component efficient synthesis of biologically active highly substituted dihydro-2-oxopyrrole derivatives with excellent yields and short reaction times. This procedure has several advantages, including use of mild, nontoxic, and inexpensive catalysts, one-pot synthesis, environmentally benign nature, simple operational procedure, and highly efficient conditions.
Computational Analysis of Chromophore Tripeptides FollowingFusion of Enhanced Green Fluorescent Protein and Cell-penetrating Peptides Widyaningtyas, Silvia Tri; Pratiwi, Ekawati Betty; Bela, Budiman
Makara Journal of Science Vol. 24, No. 4
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Cell-penetrating peptides (CPPs) are small peptides that can transfer other materials into a cellular compartment. In this research, we studied the effect of fusion of new CPPs to the N-terminal of enhanced Green Fluorescent Protein eGFP on the ability of the latter to fluoresce. Results showed that the recombinant protein CPPs-eGFP could be successfully expressed in Escherichia coli. In contrast to E. coli expressing wild-type eGFP, which could fluoresce under ultraviolet (UV) or visible light, E. coli expressing CPPs-eGFP lost their ability to fluoresce. PyMol, a molecular visualization system, revealed that fusion of the new CPPs to the N-terminal of eGFP alters interactions between chromophore-forming tripeptides and the adjacent amino acids of other tripeptides. Disrupting peptide interactions induced structural changes in eGFP that caused it to lose its fluorescence ability. We suggest performing computational analyses to predict the biological function of new fusion proteins prior to starting laboratory work.
Association between Dietary Macronutrient Intake and High-Sensitivity C-Reactive Protein Levels among Obese Women in Kuantan, Malaysia Shahadan, Siti Zuhaidah; Daud, Azlina; Ibrahim, Muhammad; Md. Isa, Muhammad Lokman; Draman, Samsul
Makara Journal of Science Vol. 24, No. 4
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Elevated high-sensitivity C-reactive protein (hs-CRP) levels may be associated with an increased risk of cardiovascular disease (CVD). In general, an individual’s dietary intake may influence the hs-CRP level. However, evidence on the influence of dietary macronutrient intake on hs-CRP levels among obese Malaysian women remains fragmented. Therefore, this study aims to investigate the association between the hs-CRP level and dietary macronutrient intake of obese adults living in Kuantan. The assessment of 24-hour dietary recall and venous hs-CRP levels were investigated in 67 women with a body mass index of 27.5 to 39.9 kg/m². The findings revealed that obese women living in Kuantan had elevated hs-CRP levels (median = 7.95 mg/L, IQR = 7.90) and a significant negative correlation between the hs-CRP level and total dietary fiber intake (r = 0.205, p =.014). In conclusion, this study suggests that certain macronutrients, particularly dietary fiber, seem to be associated with elevated hs-CRP in obese women. Hence, this information could help assess and manage low-grade chronic inflammation and underlying obesity-related conditions.

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