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ASEAN Journal on Science and Technology for Development
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.
Arjuna Subject : -
Articles 8 Documents
 1 
Search results for , issue "Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)" : 8 Documents clear
Characteristics of unsupported alumina membrane prepared using sol-gel technique M.R. Othman,; A.L. Ahmad; H. Mukhtar
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29037/ajstd.257

Abstract

A laboratory scale alumina membrane was prepared using sol-gel technique. Results from the experiment demonstrate that the addition of PVA is important for viscosity adjustment to determine the appropriate coating time if the membrane is required for coating on the porous support. The effects of varying PVA content  and sintering temperature on the characteristics of the sintered membrane are discussed. In this work, a 2 volume % of PVA solution containing 4g of PVA in lOOml of water was discovered to be adequate to achieve appropriate porosity level and avoid cracks in the gel layer. It was also discovered that the sol viscosity essentially increased as the PVA addition was increased. On the contrary, the coating time decreased as PVA content in the sol was increased. Generally, the pore size of the membrane increased with the increase in PVA addition. The density of the membrane increased with increase in sintering temperature. The porosity level however, decreased as the temperature was increased. The pore size became greater and pore size distribution wider at higher sintering temperatures.
Characteristics of unsupported alumina membrane prepared using sol-gel technique M.R. Othman,; A.L. Ahmad,; and H. Mukhtar
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (729.52 KB) | DOI: 10.29037/ajstd.306

Abstract

A laboratory scale alumina membrane was prepared using sol-gel technique. Results from the experiment demonstrate that the addition of PVA is important for viscosity adjustment to determine the appropriate coating time if the membrane is required for coating on the porous support. The effects of varying PVA content and sintering temperature on the characteristics of the sintered membrane are discussed. In this work, a 2 volume % of PVA solution containing 4g of PVA in lOOml of water was discovered to be adequate to achieve appropriate porosity level and avoid cracks in the gel layer. It was also discovered that the sol viscosity essentially increased as the PVA addition was increased. On the contrary, the coating time decreased as PVA content in the sol was increased. Generally, the pore size of the membrane increased with the increase in PVA addition. The density of the membrane increased with increase in sintering temperature. The porosity level however, decreased as the temperature was increased. The pore size became greater and pore size distribution wider at higher sintering temperatures. 
Developm ent of carboxymethylcellulose from nata de coco Lydia S. Manguiat,; Veronica C. Sabularse, and; Dario C. Sabularse Sabularse
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (790.296 KB) | DOI: 10.29037/ajstd.307

Abstract

Nata de coco was used as raw material for the preparation of food-grade carboxymethylcellulose referred to as carboxymethyl-nata (CMN). The effect of various conditions in the carboxymethylation of nata cellulose was determined. The concentration of NaOH, mercerisation time, shredding time during mercerisation and etherification, and the concentration of monochloroacetic acid significantly affected the following physico-chemical properties of CMN, namely, degree of substitution (DS), viscosity, degree of polymerisation (DP), and solubility. The best processing conditions were: the use of 40% NaOH, 60 mins mercerisation time, 60 mins shredding time during mercerisation and etherification, and J.35g/mL ClCH COOH. CMN with desirable properties wasproduced using these conditions.
Effects of pressure on thermal contact resistance for rough mating surfaces M. Z. Abdullah,; Y. C. Yau,; Z. A. Zainal Alauddin, and; K. N. Seetharamu
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (434.422 KB) | DOI: 10.29037/ajstd.308

Abstract

Thermal contact resistance has been studied experimentally to  investigate the effect of pressure between two aluminium or two brass rough surfaces at three different heat flux levels. Three different rough surfaces are considered in the range of 2.63 to 40.69?m. It is demonstrated that the thermal contact resistance reduces significantly with pressure for both materials, the harder material gives higher thermal contact resistance as expected
Forecasting water demand using back propagation networks in the operation of reservoirs in the citarum cascade, west java, indonesia Mulya R. Mashudi
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (813.795 KB) | DOI: 10.29037/ajstd.309

Abstract

This study investigates the use of Neural Networks (NN) as a potential means of more accurately forecasting water demand in the Citarum River basin cascade. Neural Networks have the ability to recognise nonlinear patterns when sufficiently trained with historical data. The study constructs a NN model of the cascade, based on Back Propagation Networks (BPN). Data representing physical characteristics and meteorological conditions in the Citarum River basin from 1989 through 1995 were used to train the BPN. Nonlinear activation functions (sigmoid, tangent, and gaussian functions) and hidden layers in the BPN were chosen for the study.
Membrane cleaning using electric pulse in dead end ultrafiltration of proteinaceous solution A.L. Ahmad'; and I.A. Azid
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (955.535 KB) | DOI: 10.29037/ajstd.310

Abstract

Dead end ultrafiltration of Bovine Serum Albumine (BSA) using a polymeric membrane has been studied. Membrane fouling for such fine biological product due to the formation of filter cake and adsorption of the proteinaceous solution is the major bottleneck for such separation process. The application of electric pulses has shown an effective means in cleaning the membrane and reducing the fouling rate for dead-end ultrafiltration of BSA. The flux is significantly increased by both electrophoretic motion of solutes away from the membrane surface and electro-osmosis occurring in the filter cake. An automated experimental rig equipped with data acquisition system has been developed to test the effectiveness and performance of such membrane cleaning. The improvement of flux becomes more pronounced with increasing electric field strength. The effects of other processing variables such as pulse interval, pulse duration, ionic strength of the electrolyte, pH of the solution and solution concentration were studied on this membrane cleaning technique. Data are analysed for its average flux, average cake concentration, average percentage of cake and water recovery for every cleaning condition. It is found out that the chemical and physical properties of the solution (pH and ionic strength of the electrolyte) have a great effect on this membrane cleaning method. Protein solution at pH 8 and 0.0 lM ionic strength of the electrolyte gave the best membrane cleaning performance. Shorter pulse interval and with relatively 10 seconds pulse duration are the optimum conditions on application of pulse to remove the filter cake from the membrane.
Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration Musa Ahmad; T.W. Tan
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (434.321 KB) | DOI: 10.29037/ajstd.311

Abstract

An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to any pH changes and could be used to determine the end-point of the acid-base titration.
The mechanical properties of fly ash concrete prepared and cured at high temperatures D.R. Munaf; M.S. Besari; M.M. IqbaP; and I. Kadir
ASEAN Journal on Science and Technology for Development Vol. 18 No. 2 (2001): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (624.565 KB) | DOI: 10.29037/ajstd.313

Abstract

Results of an experimental investigation on the effect of fly ash content, water cement (w/c) ratio of concrete prepared and cured at temperatures of ambience, 40°C and 60°C are presented in this paper. The mechanical properties investigated here include its workability, its behaviour under compression and splitting tension. Microscopic investigations were also carried out using SEM micrographic images to gain understanding of concrete at its microstructural level.The results indicate that high temperature increases early compressive strengths of concrete, but has decreasing effects on the strengths at later ages. The use of fly ash in concretes cast and cured at elevated temperatures improves the physical and mechanical properties of fresh as well as those of hardened concrete.Various mathematical models describing the properties of such concretes are considered at the end of this paper. The strength properties of high temperature fly ash concrete were best represented by a simple exponential function of time, while its stress-strain relationship could be best described by an exponential function of strain of a more complicated form.

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