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INDONESIA
Makara Journal of Technology
Published by Universitas Indonesia
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Core Subject : Science,
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Articles 4 Documents
Search results for , issue " Vol 8, No 2 (2004)" : 4 Documents clear
Wavelenght-Dispersive X-Ray Flourescence Accuration Widyatmoko, H
Makara Journal of Technology Vol 8, No 2 (2004)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v8i2.81

Abstract

X-Fuorescence spectrometry is a method, which is increasingly applied in the geochemical analysis. X-Fuorescence spectrometry is classified under two categories -WDXRF (wavelenght - dispersive X-ray fluorescence spectrometer) and EDXRF (energy-dispersive X - ray fluorescence spectrometer). WDXRF can be configured as a sequential spectrometer , a simultaneous spectrometer or a hibrid instrument, which combines the advantages of the simultaneous and sequential spectrometers into one instrument. Each instrument is different in some characteristics, and each has applications for which it is specifically suited. In this investigation sequential spectrometer PW 1450 was used to analyze the major, minor and trace elements in the samples. The standards used in calibrating the PW 1450 for the analysis of all samples are materials of known composition (30 internatioanal standards and 66 standards from Institut für Mineralogie der Uni. Köln, Germany). Interelement and matrix effects are treated by matrix matching of samples and standards, dilution, preconcentration of the element of interest, and mathematic corrections during data analysis. The examination of two samples and the statistic description using standard deviation and coefficient of variant show that the XFA is accurate enaugh for many elements, especially for the major elements, but for Mg, Ca, K, Na, P, S, Co, Rb, Zn, Ni, Ba, Pb in comparison with Atomic Absorpsion Spectrometry (AAS), Flame Emission Spectrometer (FES), Inductively Coupled Plasma (ICP) and photometer it is less sensitive. It is posible to devaluate the errors by using coefficient of variant and standard deviation.
Synthesize of Emulsion Polymer Latex for Sub-Grade CBR Improvement in The Road Construction Moto, Keba; Julian, V; Syamsudin, Syamsudin; Wiradi, T; Wijaya, Sastra K
Makara Journal of Technology Vol 8, No 2 (2004)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v8i2.82

Abstract

Synthesize of emulsion polymer latex for sub-grade CBR improvement in the road construction. Latex polymer for California Bearing Ratio (CBR) enhancement in sub-grade soil of road building has been prepared by emulsion polymerizations technique. The prepared polymer then characterize by Fourier Transform Infrared (FTIR). For application purpose, CBR test was done to the compacted polymer added-soil. The CBR test is done also for both soaked and unsoaked samples. It is found that our latex polymer is better then other imported latex polymer. For the latex polymer, which is design to have Temperatur glass (Tg) around 9.8-19.6o, indicating the formation of C=O and -C-O-C- bonds at 1732-1736 cm-1 energy absorption as binder groups. CBR test results show that our latex polymer has CBR value around 15-18 % compare to the soil without polymer binder.
Secondary Flow Experimental Study for Axial Compressor Cascade Strong Stagger With and Without Tip- Clearance: Static Pressure Distribution on Blade Surface Syamsuri, Syamsuri
Makara Journal of Technology Vol 8, No 2 (2004)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v8i2.83

Abstract

The performance of blade cascade is influenced by the growth and boundary layers separation along blade surface and endwall (casing and hub). The secondary flow which happens near hub and casing compressors is three dimentional flow separation phenomenon comes from interaction blade boundary layer with casing and hub boundary layers in the compressor. The secondary flow causes secondary losses, blockage effect, and turning angle (deflection) distribution along blade span. The result of the research shows that the increase of the angle of attack reveals lines of constan pressure to be curved forward (upstream) or pressure gives rise to spanwise caused by a strong curl flow. Separation is also increase and cross between two blades. Hence, three dimentional separation region in corner also increase.
Effect of Photoperiodicity on Co2 Fixation By Chlorella vulgaris Buitenzorg in Bubble Column Photobioreactor For Food Supplement Production Wijanarko, Anondho; Dianursanti, Dianursanti; Witarto, Arief; Soemantojo, Roekmijati
Makara Journal of Technology Vol 8, No 2 (2004)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v8i2.84

Abstract

To reduce the level of CO2 content in air, effort on converting CO2 to useful products is required. One of the alternatives includes CO2 fixation to produce biomass using Chlorella vulgaris Buitenzorg. Chlorella vulgaris Buitenzorg is applied for production of food supplement. Chlorella vulgaris Buitenzorg is also easy to handle due to its superior adaptation. Currently, Chlorella vulgaris Buitenzorg has been analyzed by some experts for its cellular composition, its ability to produce high quality biomass and the content of essential nutrition. A  series of experiments was conducted by culturing Chlorella vulgaris Buitenzorg using Beneck medium in bubbling column photobioreactor. The main variation in this experiment was photoperiodicity, where growth of Chlorella vulgaris Buitenzorg was examined during photoperiodicity condition. The difference between CO2 gas concentration of inlet and outlet of the reactor during operational period, was compared to the same experiment under continuous illumination. Under photoperiodicity of 8 and 9 h/d, the culture cell densities (N) were approximately 40 % higher than under continuous illumination. Final biomass density of Chlorella vulgaris Buitenzorg at 9 h/d illumination was 1.43 g/dm3, around 46% higher than under continuous illumination. Specific carbon dioxide transfer rate (qCO2) in photoperiodicity was 50-80% higher than under continuous illumination. These experiments showed that photoperiodicity affects the growth of Chlorella vulgaris Buitenzorg The specific  growth rate (μ) by photoperiodicity was higher than that by continuous ilumination while the growth period was two times longer. Based on the experiments, it can be concluded that photoperiodicity might save light energy  consumption. The prediction of kinetic model under continuous illumination as well as under photoperiodicity illumination showed that Haldane model became the fitted kinetic model.

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