Makara Journal of Science
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The Use of Eco-Friendly Catalyst in the Production of Ester
No full textThis study utilized an eco-friendly heterogeneous catalyst in the synthesis of ester via esterification of ethanol and acetic acid under refluxing conditions. The amount of acetic acid converted was determined by titrimetric method. Aluminum pillared material was produced from natural clay by ion exchange and calcined at 473 K. Powdered X-Ray diffraction (PXRD), Fourier Transform Infra-Red (FT-IR) and BET gas sorption analysis were employed to characterize the pillared material. The result revealed that significant improvement on physicochemical characteristics of the natural clay occurred as a result of pillaring. The results also revealed that the conversion of acetic acid was dependent on the catalyst/feed ratio of 2:2:1. The maximum conversion of acetic acid of 95.79% was obtained at the reaction temperature of 363 K and 150 minutes. The pillared clay material is more active in the conversion of acetic acid than the natural bentonite clay. This study illustrated that pillared bentonite clay is an eco-friendly solid catalyst for use in the production of chemical precursors for several industrial products
Density Profiles, Energy, and Oscillation Strength of a Quantum Dot in Two Dimensions with a Harmonic Oscillator External Potential using an Orbital-free Energy Functional Based on Thomas–Fermi Theory
No full textThis research aims i) to determine the density profile and calculate the ground state energy of a quantum dot in two dimensions (2D) with a harmonic oscillator potential using orbital-free density functional theory, and ii) to understand the effect of the harmonic oscillator potential strength on the electron density profiles in the quantum dot. This study determines the total energy functional of the quantum dot that is a functional of the density that depends only on spatial variables. The total energy functional consists of three terms. The first term is the kinetic energy functional, which is the Thomas–Fermi approximation in this case. The second term is the external potential. The harmonic oscillator potential is used in this study. The last term is the electron–electron interactions described by the Coulomb interaction. The functional is formally solved to obtain the electron density as a function of spatial variables. This equation cannot be solved analytically, and thus a numerical method is used to determine the profile of the electron density. Using the electron density profiles, the ground state energy of the quantum dot in 2D can be calculated. The ground state energies obtained are 2.464, 22.26, 90.1957, 252.437, and 496.658 au for 2, 6, 12, 20, and 56 electrons, respectively. The highest electron density is localized close to the middle of the quantum dot. The density profiles decrease with the increasing distance, and the lowest density is at the edge of the quantum dot. Generally, increasing the harmonic oscillator potential strength reduces the density profiles around the center of the quantum dot
Antifungal Activity of (+)-2,2’-Epicytoskyrin A and Its Membrane-Disruptive Action
No full text(+)-2,2’-Epicytoskyrin A, a bis-anthraquinone isolated from fungal endophyte Diaporthe sp. GNBP-10 associated with Uncaria gambir Roxb., was investigated for its antifungal activity. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) against 22 yeast strains and three filamentous fungi. The MICs of (+)-2,2’-epicytoskyrin A ranged from 16 to 128 µg/mL, which exhibited lower activity than the antifungal nystatin. A study of the mechanism of action revealed similar effects of (+)-2,2’-epicytoskyrin A and nystatin on Candida tropicalis at their MICs (16 and 8 µg/mL, respectively) and 2 times of the MIC. Both compounds caused cytoplasmic material and ion leakages on fungal cell, which were characterized by an increase in absorbance at 260 nm and 280 nm as well as Ca2+ and K+ ion concentrations. The morphology of the fungal cells after (+)-2,2’-epicytoskyrin A treatment was observed under a scanning electron microscope. The control cells, which were not treated with either (+)-2,2’-epicytoskyrin A or nystatin, showed a smooth surface, while the cells treated with either (+)-2,2’-epicytoskyrin A or nystatin shrank and displayed a donut-like shape. More shrinkage was observed in the 2 times MIC concentration and even more in the cells exposed to nystatin. The action of (+)-2,2’-epicytoskyrin A was proposed through membrane disruption
Volatile Compounds Detected in Coconut Shell Liquid Smoke through Pyrolysis at a Fractioning Temperature of 350-420 C
No full textThis study evaluated the volatile components of liquid smoke from coconut shells obtained through the pyrolysis process at fraction 350-420 °C. The volatile compounds of liquid smoke from a coconut shell were analyzed using gas chromatography and mass spectrometry (GC-MS). Nineteen peaks were detected by GC-MS in the coconut shell liquid smoke, and 19 compounds also were identified. The volatile compounds were identified as follows based on their function group’s composition percentage: phenol (90.75%), carbonyl (3.71%), alcohol (1.81%), and benzene (3.73%), respectively. The liquid smoke contains a high ratio of phenol derivatives (90.75%) in volatile profile. The phenol derivatives were the major volatile compounds found in the coconut shell liquid smoke. 
Statistical Properties of Cloud Propagation over Sumatra during CPEA-I
No full textCloud propagation over Sumatra and the surrounding area (10°S-10°N, 70°-120°E) during the Coupling Processes in the Equatorial Atmosphere-I (CPEA-I) campaign (10 April to 9 May 2004) was tracked using brightness temperature (Tb) data from the GOES-9 satellite. The cloud tracking was based on three-dimensional data with a threshold of Tb < 210 K. During the campaign, westward-moving clouds were more dominant than eastward-moving systems, with a ratio of approximately 4:1. This characteristic coincided with the dominant easterly wind aloft. Most clouds propagated with a speed varying between 4 and 35 m/s, with a mean value of 13.7 m/s. If the westward and eastward propagations were separated, the average duration, speed, and span of the westward (eastward) moving clouds are 7.7 (5.8 h), -14.5 (9.8 m/s), and 435.5 (187.1 km), respectively. The characteristics of cloud propagation during the CPEA-I were influenced by environmental factors such as relative humidity, temperature, the vertical movement of air, and wind shear. Such factors interacted with the inactive and active phases of the Madden-Julian Oscillation
Diversity and Antifungal Activity of Actinomycetes Symbiont Hard Coral Mucus of Genera Goniopora and Porites
No full textScreening new bioactive compounds from marine actinomycete organisms associated with corals (Goniopora and Porites) can be an alternative method to discover the natural antifungal compounds. This study aims to determine the density and diversity of actinomycete symbionts based on repetitive sequence-based-polymerase chain reactions (rep-PCR) and to discern the ability of antifungal activity of isolates symbiotic with hard coral mucus by using a pour plate method. A total of 143 isolates were obtained from the hard coral mucus of genera Goniopora and Porites. High genetic diversity was observed among the isolates. Ten isolates with different morphological characteristics were selected to extract its secondary metabolites and then followed by an antifungal test. The isolate with the code of SCAS324 was the one with the antifungal activity, marked by the formation of a very strong inhibition zone of 54.7±0.4 mm toward Aspergillus flavus and 49.2±2.7 mm toward Candida albicans. Antifungal screening showed that the antifungal activity of the isolate SCAS324 was three times as effective as the commercial antifungal
Vinblastine and Vincristine Production on Madagascar Periwinkle (Catharanthus roseus (L.) G. Don) Callus Culture Treated with Polethylene Glycol
No full textVinblastine and vincristine are secondary metabolites from Madagascar periwinkles that have a very high economic value as chemotherapy drugs. These compounds are naturally produced in a very low quantity in planta. One promising alternative method for vinblastine and vincristine production is to use a treatment that can trigger plant stress response in vitro. This study has been done to evaluate the effect of drought stress using polyethylene glycol (PEG) on vinblastine and vincristine production in the C. roseus callus culture, which were grown on medium Zenk supplemented with plant growth regulators (PGR) 1 μM NAA + 10 μM Kinetin to induce laticifer and idioblast differentiation. 13-week-old callus cultures were then treated with 0%, 6%, 9%, and 12% (w/v) PEG4000 each for 0, 24, 48, and 72 hours. Biochemical analysis was performed using HPLC to determine the levels of vinblastine and vincristine, while the presence of differentiated cells (idioblasts and laticifers) was determined using a histochemical method. Protein profiles of the culture were determined by SDS-Page. The results showed that drought treatment with PEG4000, until the concentration was 12% (w/v), did not significantly affect the production of vinblastine and vincristine, but might affect terpenoid production. Histochemical analysis confirmed the presence of idioblasts, non-elongated laticifers, and laticifers that were producing and accumulating terpenoids highest in the 12% PEG treatment. PEG treatments also did not change the protein profile of callus
Simulation and Experimental Study of a 2D Photonic Crystal Structure that Reflects a Quantum Dots Emission in the Normal Direction
No full textTwo-dimensional photonic crystal structures not only confine light and guide waves laterally but also reflect light in the normal direction due to a slow Bloch mode effect. However, evidence of the utilization of this structure as a mirror is required. Therefore, in this work, a simulation was made and experimental results were obtained to prove that there was an increase in the intensity of reflected CdSe colloidal quantum dots emission in the normal direction when a 2D photonic crystal structure was used. A thin TiO2 film was shaped into a two-dimensional photonic crystal structure using a simple sol-gel and polystyrene-mask-etching procedure. This structure was then placed on top of the thin CdSe quantum dots film layer. The emission of quantum dots onto the two-dimensional photonic crystal structure was compared to quantum dots emission onto a flat, thin TiO2 film. An increase in the quantum dots emission of up to 105% was in the presence of the two-dimensional photonic crystal structure. This finding is very useful for photonic device applications, such as light-emitting diodes, laser systems and bio-tagging detection systems. 
Determination of Pathotypes from Indonesian Xanthomonas oryzae Pv. Oryzae Population causing Bacterial Leaf Blight and their Reactions on Differential Rice
No full textThe objective of this work was to study the virulence of 15 Xanthomonas oryzae pv. oryzae (Xoo) isolates collected in three provinces in Indonesia (North Sumatra, South Sumatra, and South Sulawesi) based on five Indonesian differential rice genotypes and 10 near isogenic lines (NILs) that have been known to differ in their resistance to bacterial leaf blight (BLB), in a greenhouse assessment. In addition, this study also aims to monitor the responses of 31 rice genotypes (21 NILs, five differentials, five improved cultivars) to BLB disease in a field experiment. The 15 isolates showed different virulence patterns on the NILs’genotypes with a single resistance gene indicating the pathogen diversity. Eight different pathotypes were present, as demonstrated by a particular virulence pattern of each isolate on the genotypes. Determination of Xoo pathotype revealed that Xoo pathotypes responded differently based on their reaction to NILs and Indonesian differential genotypes. The field assessment demonstrated the incidence and severity of BLB disease on rice genotypes ranging from 25% to 100% and 5.5% to 72.91%, respectively, while the mean disease index ranged from 1.15% to 72.9%. The disease response varied among rice genotypes. IRBB50 (Xa4+xa5), IRBB51 (Xa4+xa13), IRBB52 (Xa4+Xa21), IRBB53 (Xa4+Xa21), IRBB56 (Xa4+xa5+xa13), IRBB57 (Xa4+xa5+Xa21), IRBB59 (Xa4+xa13+Xa21), IRBB64 (Xa4+xa5+Xa7+Xa21), IRBB66 (Xa4+xa5+Xa7+xa13+Xa21), IRBB7(Xa7), Angke (Xa4+xa5) and Code (Xa4+Xa7) were revealed to be highly resistant to the BLB pathogen. These genotypes have potential as genetic material for the pyramiding of several resistance genes for the development of rice resistance to BLB disease in Indonesia
Identification of MADS-box Gene in Oil Palm (Elaeis guineensis Jacq.)
No full textThe bunch size represented by the fruit number is the main parameter of oil palm (Elaeis guineensis Jacq.) yield. The fruit number, which is determined during the initial phase of development, is related to various factors, including the genetic properties of the trees. Trees that have more pistillate flowers have more fruit. The diversity of MADS-box genes assumed can be used as a marker for trees that have a higher number of pistillate flowers. Therefore, the aims of this research were to isolate and identify the MADS-box genes from flowers of tenera oil palm using PCR techniques. The SQUAMOSA (SQUA) gene and the GLOBOSA (GLO) gene are members of the MADS-box genes family that are responsible for sepal, petal and stamen organ development. The genomic DNA of the staminate flowers of trees that have more staminate flowers (P1) and the genomic DNA of the pistillate flowers of trees that have more pistillate flowers (P2) were isolated using the CTAB+ PVP method. The CTAB+PVP method was more efficient for isolating pistillate flower genomic DNA than staminate flower genomic DNA. The genomic DNA of P1 and P2 was amplified with two primers: BMS and BMG. The BMS primers gave a PCR product size of 1250 bp for the genomic DNA of P1 and P2. Meanwhile, the BMG primers gave a PCR product size of 1250 bp and 1300 bp for P1 and P2, respectively. The PCR products were sequenced and analyzed for homology using the GenBank database. BLAST analysis showed the PCR products have high homology with the SQUA1 gene and the GLO2 gene. Alignment analysis showed that the DNA fragments amplified with the BMS primers of the P1 and P2 sequences have variations in the exons and introns, and the variations were observed only in the introns of the DNA fragments amplified with the BMG primers.