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ASEAN Journal on Science and Technology for Development

ajstd
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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 8 Documents

Search results for , issue "Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)" : 8 Documents clear

Correlation Between Thermal Diffusivity Variation and Quality of Cold Preserved Fish F.A Ansari; K.A Abbas; M.M.H Megat Ahmad
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The present paper deals with establishment of correlation between thermal behaviour and quality of cold preserved fish. Experiments were designed and transient temperature-time variations were recorded at the center and other three equidistant locations during air blast cooling of slab shaped pieces of fresh water fish. A number of pieces from the same lot were cold preserved at 3°C for a period of 28 days and experiments were repeated daily. Time-temperature records were used to determine thermal diffusivity of each sample using the empirical approach of the first author, reported elsewhere. It was observed that the measured thermal diffusivity increased up to 14 days and then stayed approximately constant up to the end of the preservation period (28 days). According to the reported literature, it was found that the shelf life of fish preserved at 3°C is 14 days. Regression analysis was made to develop an empirical correlation between thermal diffusivity and preservation time of the fish under investigation.

Chemical Precipitation and Coatings of Tin Selenide Z Zainal; N Saravanan; K Anuar; M.Z Husein; W.M.M Yunus
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Tin selenide were prepared chemically in alkaline aqueous solution. The crystalline powder was coated onto microscope glass slides using polyvinyl alcohol solution. The coatings were subjected to annealing at various temperatures to study the effect towards the structure, morphology and composition of the material. The product prepared was characterised using various techniques. The photoresponse for the samples were also studied. The photoelectrochemical (PEC) cell configuration was p-SnSe | (0.01 M K4Fe(CN)6¾0.01 M K3Fe(CN)6.3H2O¾0.1 M Na2SO4| Pt).

Cathodic Electrodeposition and Characterization of ni3se2 thin Films K Anuar; Z Zainal; N Saravanan; A.R Kartini
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Nickel selenide thin films have been potentiostatically electrodeposited on titanium substrate at room temperature from aqueous solution containing Ni-EDTA and Na2SeO3. Various deposition potentials were attempted in order to determine the optimum electrodeposition potential. The films were characterised using x-ray diffraction analysis (XRD) and the photoactivity of the electrosynthesised films were studied using linear sweep voltammetry (LSV). The band-gap energy was determined using UV-visible spectroscopy. The XRD analysis indicated the formationof polycrystalline Ni3Se2. The film exhibited p-type semiconductor behaviour with good photosensitivity. The bandgap energy (Eg) was about 1.4eV.

Optical Response of Poly (1,4-Phenylene-1,2-Di (P-Phenoxyphenyl) Vinylene) Towards Oxygen Gas F.S Mehamod; R Daik; M Ahmad
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

This research involved the synthesis of poly (1,4-phenylene-1,2-di (p-phenoxyphenyl) vinylene), dpop-PDV from di (p-phenoxybenzoyl) benzene compound as the monomer. The potential of the produced polymer as sensing reagent for O2 detection based on fluorescence quenching was studied. Di (p-phenoxybenzoyl) benzene was synthesised via the Friedel-Crafts benzoylationwith terephthaloydichloride and biphenylether as starting materials and anhydrous AlCl3 as the catalyst, while the dpop-PDV was synthesized via the McMurry coupling reaction. The polymerization was carried out in THF with TiCl4 and Zn as the catalyst and reducing agent respectively. Characterization on monomer and polymer had been carried out by using FTIR, GCMS, DSC, TGA, GPC and melting point measurement. Response of the polymer towards oxygen gas was described in terms of fluorescence spectra, repeatability, reproducibility and the response curve. Results obtained showed that the fluorescence intensity decreased upon exposure to O2 gas, indicating that the polymer was responsive to the presence of the O2 gas and the sample was found regenerable by flushing the polymer solution with N2 gas.

Mesoporous Inorganic Membrane Reactor for Oxidative Coupling of Methane N.C May; A.R Mohamed; S Bhatia
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The mesoporous inorganic membrane has been developed and characterized for oxidative coupling of methane reactions. In this research, g-alumina membrane was modified with Lanthanum. The membrane has shown thermal stability in prolonged exposure to the high-temperature application of 600-900°C. The results were confirmed by TGA and OCM experimentations. TGA results showed only 2-3% loss from an initial weight that is mainly due to evaporation of water and release of the nitrate compound. The membrane was also found stable for at least a month of operationwhile the catalyst was being regenerated to regain its activity. The SEM cross-sections show successful deposition of Lanthanum in spite of its non-uniform deposition layer and crack formation.

Associations of Common ?-Thalassemia Mutations With ?-Globin Gene Frameworks in Northern Thailand P Sanguansermsri; D Shimbu; R Wongvilairat; T Sanguansermsri
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

This study aimed to characterize polymorphism of the b-globin gene (framework) among common b-thalassemia mutations found in northern Thailand. Thirty-one homozygous b-thalassemia major patients admitted to Chiang Mai University Hospital were identified using direct DNA sequencing method. Among 15 patients with homozygous of codon 41/42 (-TCTT), eight were homozygous of framework 1 (FW1), one was homozygous of FW3A, and the remainders were heterozygousof FW1 and FW3A. The gene frequencies of FW1 and FW3A in the patients were 0.733 (22/ 30) and 0.267 (8/30), respectively. All 11 patients with homozygous of codon 17 (A-T) were homozygous of FW3A, while three patients with homozygous of intron 1 nt 1 (G-T) were homozygous of FW1. Both patients with homozygous of codon 71/72 (+A) were FW3A. In this report, the numbers of b-globin gene frameworks were restricted in each b-thalassemia mutation. This investigation may provide further information for the study of the evolution of common mutations causing b-thalassemia major in northern Thailand.

Characterization of Lignin Precipitated From The Soda Black Liquor of Oil Palm Empty Fruit Bunch Fibers by Various Mineral Acids M.N Mohamad Ibrahim; S.B Chuah; W.D. Wan Rosli
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Soda lignin from oil palm empty fruit bunch was directly isolated by various mineral acids i.e. sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid at three levels of concentration (20% v/v, 60%v/v and concentrated). A comparison study was performed through physicochemical properties and structural features using FT-IR, UV, 13C-NMR and nitrobenzene oxidation. The FT-IR results showed that there is no significant difference between the main structures of the lignin isolated by various acids. However, low concentration of phosphoric acid is preferable because of its highest yield. The S: V: H ratio of 7-15:6-11:1 as evaluated by the nitrobenzene oxidation procedure suggests that soda lignin can be classified as belonging to either the cereal straw on grass type. The UV results indicate that phosphoric acid consistently gave the highest absorbance value among the four acids tested in this study regardless of its concentration level. The C13-FTNMR spectra, suggest that the lignin structure is independent of the type of acid used for precipitation.

Dynamic Mechanical Thermal Analysis (DMTA) of Thermoplastic Natural Rubber (TPNR) Barium Ferrite (bafe12o19) Composites S Hamdan; D.M.A Hasihim; M Yusop
ASEAN Journal on Science and Technology for Development Vol. 21 No. 1 (2004): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

filled with 0-6 volume percentage of barium ferrite was performed using a Polymer Laboratory- Dynamic Mechanical Thermal Analyser (PL-DMTA) over a range of temperature from -100 to 100°C at 10hz. The results showed that the storage modulus (E') of the composites below the transition temperature increase with filler content up to ~3-4 volume percentage. Incorporation of the filler does not change the matrix glass transition that occurs around -40°C but the damping curve becomes broader with increasing filler content. The addition of filler in the compositedoes not affect the glass transition and melting temperature. The blend of TPNR and barium ferrite powder is only a physical mixture that does not act chemically.

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