Makara Journal of Science
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Characterizing Particle Board Made of Oil Palm Empty Fruit Bunch Using Central Composite Design
No full textParticle board was made using processed oil palm empty fruit bunch and casein glue. This research used two factor variables and eight response variables to determine the best matrix/filler ratio and compression pressure for particle board production. The factor variables, (matrix/filler ratio and compression pressure), determined the response variables: modulus of rupture, water content, density, tensile strength, and both endothermic-and-exothermic temperatures and heats. This research aimed to optimize the mechanical and physical property of particle boards by using the bunch/glue ratio. The processing of data was undertaken by Response Surface Method (RSM) with Central Composite Design (CCD). The optimal conditions under which particle board created were at matrix/filler ratio of 50:50 and compression pressure of 3.53 kg/cm2; resulting in a modulus of rupture of 325.32 kg/cm2, water content of 0.009%, density 0.826 g/cm3, and tensile strength of 2.573 kg/cm2. This research also indicates that casein glue results in particle board with optimum parameters of endothermic temperature of 247.74 °C, an endothermic heat of -4.122 mW, exothermic temperature of 431.08 °C, and exothermic heat of 7.526 mW. Based on physical testing, most particle board properties obtained fulfilled the standards of water content and density as required by the Indonesian National Standard/SNI 03-2105-2006
Development of an environment-friendly and solvent-free synthetic route for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones/thiones by La(NO3)3.6H2O as an efficient catalyst
No full textFacile and environment-friendly procedure for the synthesis of corresponding 3,4-dihydropyrimidin-2-(1H)-ones/thiones derivatives were developed via one-pot three-component Biginelli reaction between β-keto esters (methyl or ethyl acetoacetate), aromatic aldehyde (benzaldehye derivatives) and urea or thiourea in the presence of Lanthanum (III) Nitrate Hexahydrate (La(NO3)3.6H2O) as highly efficient catalyst under solvent-free conditions. This protocol has advantages such as readily, inexpensive and non-toxic catalyst, simple reaction work-up catalyst, high atom-economy, excellent yields and short reaction times.  
Influences of Zn Concentration on Dielectric Properties of ZnxNi1-xFe2O4 Magnetic Nanoparticles
No full textDielectric properties of ZnxNi1-xFe2O4 magnetic nanoparticles (MNPs) with various Zn concentration (x = 0.2-0.8) have been investigated over a wide frequency range 5–120 kHz. Zn-Ni ferrite MNPs have spinel cubic structure. The crystallite size of the sample for x = 0.2 was about 21.5 nm and then decreases by increasing Zn concentration. For sample with x = 0.4 at frequency 20 kHz, the real dielectric constant ( ) was 35.9, imaginary dielectric constant ( ) was 20.4 and loss tangent ( ) was 0.6. Zn concentration would affect to availability of ferrous and ferric ions in the octahedral site which are preferentially occupied by Zn2+ ion. The dielectric constants decrease with increasing frequency. The sample with at x = 0.6 has the highest dielectric on frequency 5 kHz. The maximum AC conductivity ( ) was 1.7 10-4 Ω-1 at 65 kHz observed for concentration x = 0.3. The dielectric constants and conductivity at low frequency are due to the existence of grains boundary while the dispersion in the high frequency region are due to the conducting grains
QSAR Studies of Nitrobenzothiazole Derivatives as Antimalarial Agents
No full textQuantitative Structure and Activity Relationship (QSAR) analyses were carried out for a series of 13 nitrobenzothiazole derivatives as antimalarial compounds to find out the structural relationship of their antimalarial activities against the W2 Plasmodium falciparum strain. The electronic descriptors have been determined using the atomic net charges (q), dipole moment (μ), ELUMO, EHOMO, polarizability (α) and Log P. In addition, the descriptors were calculated through HyperChem for Windows 8.0 using the PM3 semi-empirical method. The antimalarial activities (IC50) were taken from literature [1]. Furthermore, the QSAR model was determined by multiple linear regression (MLR) approach, giving equation model of QSAR: Log IC50 = 41.483 + 54.812 (qC2) – 50.058 (qS3) + 416.766 (qC4) + 440.734 (qC5) – 754.213 (qC7) – 73.721 (qC8) + 246.715 (qC9) + 0.551 (μ) – 13.269 (EHOMO) – 3.404 (ELUMO) + 0.042 (α) + 0.107 (Log P). The most statistically significant QSAR model with correlation coefficients n = 13, (r) = 1.00, (r2) = 1.00, SE = 0, and PRESS = 3.40 were developed by MLR. Based on the model of the above QSAR equation 43 new nitrobenzothiazole derivatives were modeled and 24 of these compounds showed high antimalarial activity. It is recommended that these are synthesized for further investigation 4 new compounds (45, 49, 52 and 55) show equivalent activity to that achieved with chloroquine antimalarial drugs
Morphological and Structural Studies of ZnO Micro-Nanorod Structures Synthesized Using a Low-Cost Hydrothermal Method
No full textMicro-nanorod structures of zinc oxide (ZnO) have been successfully synthesized via a simple and low-cost hydrothermal method. ZnO solutions with different concentrations of 0.05 and 0.1 M were prepared using zinc nitrate tetrahydrate and hexamethylenetetramine precursors. They were dissolved in aquades and stirred before the hydrothermal process at 95 °C for 4 hours in an oven. Extensive characterizations using scanning electron microscope (SEM) and X-ray diffraction (XRD) were conducted on ZnO powder samples. SEM results showed that hexagonally shaped ZnO micro-nanorods were formed with diameters ranging from hundreds of nanometers to several micrometers. The ZnO sample synthesized at 0.05 M was observed to have a better surface morphological structure than the 0.1 M sample. In addition, XRD measurements confirmed that samples exhibited a hexagonal crystal structure of ZnO. Moreover, the calculated crystallite sizes of ZnO using the Debye-Scherrer equation using the full-width half maxima of the XRD peaks were 25.153 nm for the 0.05 M sample and 28.707 nm for the 0.1 M sample. The most prominent growth of ZnO had 101 plane orientation or nonpolar a-plane followed by nonpolar 100 m-plane and 002 polar c-plane orientations. This study offers a simple and low-cost route to produce high-quality ZnO micro-nanorods for use in various electrical and optical devices
Determination of Polycyclic Aromatic Hydrocarbons (PAHs) Using Environmentally Friendly Liquid Chromatography
No full text An analytical method to determine polycyclic aromatic hydrocarbons (PAHs) is required to obtain high-quality analytical results. The purpose of this study is to achieve good separation of a few PAHs by using environmentally friendly liquid chromatography. Accordingly, a liquid chromatograph incorporating a fluorescence detector, UV detector, and a capillary column is employed herein to simultaneously minimize the use of chemicals and obtain analytical results better than those obtained using a conventional column. Observation parameter include single analysis of each PAH, method validation, the new stationary phase, the effect of mobile phase concentration, and Quencher effect. The PAHs tested include naphthalene, phenanthrene, anthracene, fluoranthene, and pyrene. The test results show that when using an acetonitrile concentration of 100%, the retention times of different PAHs do not differ significantly. Furthermore, upon decreasing the acetonitrile concentration, the retention time increases, and better separation was achieved. The value ranges of precision, LOD, LOQ, and linearity are 3.43–12.42%, 4.7–15.1 mg/L, 15.6–50.5 mg/L, and 0.87–0.99, respectively. The new Sil-S-ImC30 stationary phase showed good results in terms of separation of PAHs. Likewise, the use of 60, 70, 80, and 90% acetonitrile as the mobile phase in combination with 0.03 M acrylamide as the quencher affected retention time but not separation. 
Isolation and Characterization of Cellulose from Underexploited Golden Melon Skin
No full textGolden melon skin (GM) is an underexploited plant resource in Nigeria from which cellulose (GMC) was isolated and characterized. Characterization was achieved using Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis, and scanning electron microscopy. GMC was further evaluated for its water holding capacity (WC), oil holding capacity (OC), water swelling capacity (SC), and heavy metal adsorption capacity. FT-IR spectroscopy revealed peaks corresponding to GMC, while the XRD diffraction planes exhibited by GMC were typical of cellulose I crystals with a crystallinity index of 40%. The thermal degradation of GMC revealed a first mass loss at 190–295 °C, second loss at 305–410 °C, and third loss 285–430 °C. The WC was 11.62 g/g, OC was 2.75 mL/g, and SC was 9.32 mL/g. The heavy metal adsorption capacity of GMC toward Cu (II) was 34.52 mg/g, and it was 28.73 mg/g toward Pb (II) in an aqueous solution. These results show that GM is a potential source of cellulose, which might have useful applications
Kinematic and Thermodynamic Structures of Mesoscale Convective Systems During Heavy Rainfall in Greater Jakarta
No full textA mesoscale convective system (MCS) is a large complex convective cloud system associated with a contiguous rainfall area that contributes significantly to heavy rainfall. This study analyzed the kinematic and thermodynamic structures of MCS during a heavy rainfall event. The MCSs that coincided with the heavy rainfall event and covered GJ occurred on January 17, 2013, 2014, and February 9, 2015. The three MCS cases were described from satellite observations over GJ during heavy rainfall. The main data consisted of satellite cloud top temperatures and national weather service soundings. We found a cloud shield with a temperature ≤ 221 K size and size less than 30,000 km2 at the mature stage of the MCS. Low moisture convection was unstable prior to MCS development. The warm moist air at 500–400 hPa could contribute to heavy rainfall above GJ. We suspect that the strong low-level convergence winds produced an updraft, and high moist air led to a developing convective cloud. The moist atmosphere on the third MCS was not always higher than others, but wind was low. These conditions caused the high intensity of heavy rainfall that occurred in GJ on the third MCS
Construction of pcDNA3.1 Vector Encoding rpfD Gene of Mycobacterium tuberculosis
No full textTuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis). TB is still a major health problem. The Bacillus Calmette-Guérin (BCG) vaccine is the only one available for TB and is known to confer variable levels of protection. Because of this variability, a new vaccine is needed to control TB. Proteins secreted by M. tuberculosis are known to induce protective immunity. Within the genome of M. tuberculosis, there is a family of proteins called resuscitation promoting factor (Rpf), which plays a role in the reactivation of M. tuberculosis. RpfD is a member of the Rpf family that has been shown to be immunogenic, making it suitable for use as a TB vaccine. The rpfD gene of the M. tuberculosis Beijing strain from the bacterial stock of the Department of Microbiology at the Medical Faculty of the Universitas Indonesia was amplified using polymerase chain reaction (PCR) and then inserted into the mammalian expression vector pcDNA3.1(+). Then, the pcDNA3.1(+)-rpfD vector was transformed to Escherichia coli DH5α. A 465-bp target fragment was obtained, and the accuracy of the cloning was confirmed using colony PCR, restriction enzyme digestion, and sequencing. We expect that this recombinant plasmid will induce immunity in future animal models and thus will prove itself to be a candidate for an M. tuberculosis vaccine
Assisted Surface-state Recombination of Orange-peel Carbon Nanodots in Various Matrices
No full textThe contentious origin of the luminescence of carbon nanodots (CDs) has attracted considerable attention. In this work, we synthesized CDs from orange peel by using a microwave-assisted technique. We investigated the optical properties of the synthesized CDs. Moreover, we studied the effect of matrix addition on the optical properties of CDs. We found that matrix addition significantly influences the absorbance and photoluminescence of CDs. Shifts in absorbance peak intensity and emission peak wavelength indicated that the bonding of matrix molecules on the surfaces of the CDs has changed the structures of CDs. This finding is supported by the extended half-life of CDs after matrix addition. Our results will expand research on the use of CDs as phosphorescent materials