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ASEAN Journal on Science and Technology for Development

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Published by Universitas Gadjah Mada

ISSN : 22249028 EISSN : 22249028 DOI : -

Core Subject : Science, Education, Engineering,

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Computer Science & IT Mathematics

The coverage is focused on, but not limited to, the main areas of activity of ASEAN COST, namely: Biotechnology, Non-Conventional Energy Research, Materials Science and Technology, Marine Sciences, Meteorology and Geophysics, Food Science and Technology, Microelectronics and Information Technology, Space Applications, and Science and Technology Policy, Infrastructure and Resources Development.

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Articles 477 Documents

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BLACK AND WHITE LAHAR AS INORGANIC SUPPORT FOR THE IMMOBILIZATION OF YEAST INVERTASE Veronica C. Sabularse; Mayrene T. Tud; Marivic S. Lacsamana; Josefina L. Solivas
ASEAN Journal on Science and Technology for Development Vol. 22 No. 4 (2005): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Volcanic ejecta or lahar can serve as an inorganic support for the immobilization of invertase. Pampanga and Bicol lahar samples were pretreated by ignition at 550oC for 5 hrs followed by concentrated hydrochloric acid treatment, activatedby reaction with aminopropyltriethoxysilane (APTS) and then covalently bound to invertase using glutaraldehyde as linker. Chemical tests confirmed the attachment of APTS to lahar and glutaraldehyde to silanized lahar. The quantity of immobilized invertase on Pampanga white, Pampanga black and Bicol black lahar were 98.73%, 96.73% and 84.27%,respectively. Conditions for maximum activity of invertase immobilized on Pampanga white lahar were pH 3.5, 45oC and 0.3 M sucrose concentration. The Kmand Vmaxfor free invertase and immobilized invertase on Pampanga white lahar were 2.37 M and 48.75 mmol/min, and 3.88 M and 38.87 mmol/min, respectively. Invertase bound to Pampanga white lahar was most stable towards repeated and continuous use and towards storage with intermittent use as indicated by its relatively greater activity.

RECYCLED PET FOR RICE HUSK/POLYESTER COMPOSITES I. Ahmad; D. R. Abu Bakar; S. N. Mokhilas; A Ramli
ASEAN Journal on Science and Technology for Development Vol. 22 No. 4 (2005): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Rice husks were combined with unsaturated polyester resin, synthesized from glycolysed product of poly (ethylene terephthalate) (PET) waste to form rice husk (RH)/polyester composites. PET from post-consumer soft drink bottles was recycled through glycolysis, followed by polyesterified with maleic anhydride and then cross-linked with styrene to producea formulation for the resin. Characterizations of the synthesized resin were performed byhydroxyl, acid values and Fourier Transform InfraRed (FTIR) techniques. The effect of filler loading and surface modification of rice husks on the mechanical properties of the composites were also investigated. It has been observed that the increasing filler loading resulted in reduction of tensile strength, elongation at break and impact strength but increased tensilemodulus and hardness. At similar filler loading, alkalized filler composites have higher mechanical properties.

PHOTOCATALYTIC REMOVAL OF TR I- AND HEXA-VALENT CHROMIUM IONS FROM CHROME-ELECTROPL ATING WASTEWATER Puangrat Kajitvichyanukul; Chulaluck Changul
ASEAN Journal on Science and Technology for Development Vol. 22 No. 4 (2005): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

A novel technique based on photocatalysis was applied to eliminate chromium ions, a toxic hazardous environmental pollutant. The photoreduction of each species of chromium (total, hexavalent, and trivalent chromiums) from chrome-electroplating wastewater was investigated using a titanium dioxide suspension under irradiation by a low-pressure mercury lamp. The initial concentration of total chromium was 300 mg/l. The applied conditions were the direct photocatalytic reduction process at pH 3.65 and the indirect photocatalytic reduction with added hole scavengers at the same solution pH. Results from both processes were comparatively discussed. Result show that chromium was not efficiently removed by direct photoreduction. In contrast, with the adding of hole scavengers, which were formate ions, the photoreduction of chromium was very favorable. Both hexavalent and trivalent chromiums were efficiently removed. The photocatalytic mechanism is purposed in this study.

SUITABILITY OF SAGO STARCH BLENDED WITH ACRYLAMIDE AS AN ADDITIVE ON HANDSHEETS MADE FROM RECYCLED PULP FIBERS Wong Sin Yeng; Paridah Md. Tahir; Liew Kang Chiang
ASEAN Journal on Science and Technology for Development Vol. 22 No. 4 (2005): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

This study was carried out to determine the suitability of sago starch blended with acrylamide as paper additive. Solutions of unmodified and blended sago starch with acrylamide, were prepared at 5% weight over volume (w/v) basis before the basic properties (i.e., pH, viscosity and solid content) were determined. Thestarches were thenused to coat on laboratory made handsheets from recycled pulps. Various effects were studied, namely, modification of sago starch, addition of different types of initiator and further curing at different temperatures. The incorporation of acrylamide into sago starch through blending signif icantly increased the pH and viscosity of the solutions. All the blended starches remained biologically resistant even after 14 days of exposure to ambient temperature. Solutionof sago starch blended with acrylamide, gave superior performance when coated on the handsheets, producing handsheets with high folding endurance (110 times) and crushstrength (128 N) ascompared to the handsheets coated with the unmodified sago starch. Nevertheless, the smoothness and air permeance of these papers were unsatisfactory due to insufficient curing shown by the micrographs. The use of ceric ammonium nitrate (CAN) as initiator and further curing at 50oC however, were able to improve the smoothness and air permeance properties.

STUDIES ON FUCOIDAN AND ITS PRODUCTION FROM VIETNAMESE BROWN SEAWEEDS Bui Minh Ly; Ngo Quoc Buu; Nguyen Duy Nhut; Pham Duc Thinh; Tran Thi Thanh Van
ASEAN Journal on Science and Technology for Development Vol. 22 No. 4 (2005): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Sulfated fucans are among the most widely studied of all the sulfated polysaccharides of plant origin that exhibit biological activities in mammalian systems. In this report fucoidans from some Vietnamese Sargassumspecies such as S.polycystum, S.oligocystum, S.mcclurei, S. Swartzii and denticaprum were extracted and fractionated on a DEAE-Sephadex A-25 column. On the basis of chemical and spectral analyses, the fucoidan fractions obtained were found to be the sulfated fucogalactans containing sulfate ester groups and uronic acid, and composed essentially of fucose and galactose, as well as a minor amount of other sugars. The polysaccharide fractions were tested for anticancer activity. The primarily obtained results showed that all fucoidan fractions isolated from S. swartziidemonstrate bioactivity effects against cancer cells, while fraction F5 with a highest sulfate content exhibits the strongest anti-invasion activity. This indicates that sulfate content plays an important role in the anticancer activity of the brown algal fucoidans. A laboratory scale pilot for fuco idan production from Vietnamese brown seaweeds has been set with a capacity of 500 g of crude fucoidan per day.

New Approach of Highly Efficient Fermentation Process for Bio ethanol using Xylose as Agricultur e Residues Abu Saleh Ahmed; Seiya Watanabe; Sinin Hamdan; Tsutomu Kodaki; Keisuke Makino
ASEAN Journal on Science and Technology for Development Vol. 27 No. 1 (2010): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Agricultural waste biomasshas already been transferred to bioethanol and used as energy related products, although many issues such as efficiency and productivity still exist to be overcome. In this study, the protein engineering was applied to generate enzymes with completely reversed coenzyme specificity and developed recombinant yeasts containing those engineered enzymes for construction of an efficient biomass-ethanol conversion system. Recombinant yeasts were constructed with the genes encoding a wild type xylose reductase (XR)and the protein engineered xylitol dehydrogenase (XDH)(with NADP) of Pichiastipitis. These recombinant yeasts were characterized based on the enzyme activity and fermentation ability of xylose to ethanol. The protein engineered enzymes were expressed significantly in Saccharomycescerevisiaeas judged by the enzyme activity in vitro. Ethanol fermentation was measured in batch culture under anaerobic conditions. The significant enhancement was found in Y-ARSstrain, in which NADP+-dependentXDH was expressed; 85% decrease of unfavorable xylitol excretion with 26% increased ethanol production, when compared with the reference strain expressing the wild–type XDH.

S tudies on the phase transitions and properties of tungsten (VI) oxide nanoparticles by X - Ray diffraction (XRD) and thermal analysis S.F. Abdullah; S. Radiman; M.A. Abdul Hamid; N.B. Ibrahim
ASEAN Journal on Science and Technology for Development Vol. 27 No. 1 (2010): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Tungsten (VI) oxide, WO3nanoparticles were synthesized by colloidal gas aphrons(CGAs) technique.The resultant WO3nanoparticleswere characterized by thermogravimetric-differential thermal analysis (TG-DTA) and X-Ray diffraction (XRD) measurements in order to determine the phase transitions, the crystallinity and the size of theWO3nanoparticles. As a comparison, transmission electron microscope (TEM) was used to investigate the size of the WO3nanoparticles. The result from XRD and DTA show that the formation of polymorphsWO3nanoparticles have the following sequence: orthorhombic (b-WO3)®monoclinic (g-WO3) ®triclinic (d-WO3) ®monoclinic (e-WO3) with respect to the calcination temperature of 400, 500, 600 and 700°C. No diffraction peaks were found in the X-Ray diffraction measurements for the sample heat treated at 300°C (as-prepared), suggesting that an amorphous structure was obtained at this temperature whereas the crystallinity had been obtained by the other samples of theWO3nanoparticles at the calcination temperatures of 400, 500, 600 and 700°C. It is also found that the X-Ray diffraction measurements produced an average diameter of (30 ±5), (50 ±5), (150 ±10) and (200 ±10) nm at calcination temperatures of 400, 500, 600 and 700°C respectively by using Debye-Scherrer formula. The TG curve revealed that the WO3nanoparticles is purely anhydrous since the weight loss is insignificant (0.3 –1.4) % from 30 until 600°C for the WO3nanoparticles calcined at 400°C. Finally, the composition and the purity of the WO3nanoparticleshave been examined by X-Ray photoelectron spectroscopy (XPS). Theresults indicate no significant changes to the composition and the purity of the WO3nanoparticle produced due to the temperature variations

CATHODIC ELECTRODEPOSITION OF Cu 4 SnS 4 THIN FILMS FROM ACIDIC SOLUTION Anuar Kassim; Ho Soon Min; Tan Wee Tee; Abdul Halim Abdullah; Atan Sharif; Md. Jelas Haron; Saravanan Nagalingam; Zulkefly Kuang
ASEAN Journal on Science and Technology for Development Vol. 27 No. 1 (2010): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

In this work the synthesis of copper tin sulfide thin films by electrodeposition is carried out. The films were deposited onto ITO glass substrates from anaqueous solution bath containingcopper sulfate, tin chloride and sodium thiosulfate at pH 1 and room temperature. Prior to the deposition, a cyclic voltammetry experiment was carried out between two potential limits (+1000 to -1000 mV versus Ag/AgCl) to probe the effect of the applied potential and to determine the most likely suitable electrodeposition potential for the deposition of copper tin sulfide. The deposition was attempted at various cathodic potentials such as -400, -600, -800, -1000 mV to determine the optimum deposition potential. The films have been characterized by techniques such as optical absorption, X-ray diffraction and atomic force microscopy. The XRD patterns show that the films are polycrystalline with orthorhombic structure. The AFMstudies reveal the electrodeposited films were smooth, compact and uniform at deposition potentials of –600 mV versus Ag/AgCl. The direct optical band-gap energy was obtained to be 1.58 eV.

Energy cost of seed drying Weerachet Jittanit; George Srzednick; Robert Driscoll
ASEAN Journal on Science and Technology for Development Vol. 27 No. 1 (2010): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

In this work, the energy costs of drying corn, rice and wheat seeds between 3 drying options were compared. They consisted of 1) two-stage drying by using fluidised beddrye (FBD) in the 1ststage and in-store dryer (ISD) in the 2ndstage, 2) single-stage drying by fixed bed dryer (FXD) and 3) two-stage drying by using FXD in the 1ststage and ISD in the 2ndstage. The drying conditions selected for comparison were proved to be safe for seed viability by the previous studies. The results showed that the drying options 2 and 3 consumed less energy than option 1. However, the benefits from lower energy cost must be weighed against some advantages of using FBD. Furthermore,it appeared that running the burners of FXD and ISD for warming up the ambient air during humid weather condition could shorten drying time significantly with a little higher energy cost.

Mixed - mode Operating System for Real - time Performance Hasan M. M.; Sultana S.; Foo C.K.
ASEAN Journal on Science and Technology for Development Vol. 27 No. 1 (2010): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The purpose of the mixed-mode system research is to handle devices with the accuracy of real-time systems and at the same time, having all the benefits and facilities of a matured Graphic User Interface(GUI)operating system which is typicallynon-real-time. This mixed-mode operating system comprising of a real-time portion and a non-real-time portion was studied and implemented to identify the feasibilities and performances in practical applications (in the context of scheduled the real-time events). In this research an i8751 microcontroller-based hardware was used to measure the performance of the system in real-time-only as well as non-real-time-only configurations. The real-time portion is an 486DX-40 IBM PC system running under DOS-based real-time kernel and the non-real-time portion is a Pentium IIIbased system running under Windows NT. It was found that mixed-mode systems performed as good as a typical real-time system and in fact, gave many additional benefits such as simplified/modular programming and load tolerance.

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