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Teknologi Indonesia

JTI
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Published by Lembaga Ilmu Pengetahuan Indonesia

ISSN : 01261533 EISSN : 23031913 DOI : -

Core Subject : Science,

Computer Science & IT

JTI is a journal in the Departement of Engineering Sciences - Indonesian Institute of Sciences (LIPI). JTI has policy to publish a new and original research paper or a review paper in The scope of Technology. JTI publishes two issues per year. The journal has been registered with printed-ISSN number as 0126-1533 and electronic ISSN number as 2303-1913.

Arjuna Subject : -

Articles 163 Documents

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STUDY OF MSSBAUER SPECTROSCOPY ON FE90-XMN10ALX (X = 10, 20, 30, AND 40 AT. %) BCC PHASE NANOCRYSTALLINE ALLOYS Tarigan, Kontan; Ginting, Masno
Teknologi Indonesia Vol 36, No 3 (2013)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v36i3.208

Nanocrystalline alloys of Fe90-xMn10Alx (x= 10, 20, 30, and 40 at. %) were prepared via mechanical alloying technique using Fe, Mn, and Al commercial powders with a 48-hr milling time. Mssbauer spectroscopy show hyperfine field distribution (HFD) varied according to Fe content. HFD with concentration of x = 10, 20 dan 30 at. % repealed sexted structure and to be narrow with increasing of concentration x, and HFD shifted to smaller field value, i. e. 298.6, 262.6 and 240.8 kOe. For smallest Fe content (x = 40 at. %) repealed singlet spectrum with positive isomer (? ? 0,067 mm / s) without detected the HFD.

SUB-ACUTE TOXICITY STUDY OF CENTELLA ASIATICA AQUEOUS EXTRACT ON THE LIVER OF RATS: DOSE-RESPONSE RELATIONSHIP ASSESSMENT Wiyono, Tri; Nurlaila, -
Teknologi Indonesia Vol 38, No 2 (2015)
Publisher : LIPI Press

Pegagan or Centella asiatica (CA) is a quite popular medicinal plant which has various properties such as anti-inflammatory and wound healing. Unfortunately, research on the toxicity of CAis still hard to find. Toxicity test of CA on spermatogenesis process had been done in previous research meanwhile its long term toxicity test has not been done. The aims of this study were to evaluate the toxicity of CA aqueous extract and to determine the relationship between the dose and toxic response when given to rats within 15 days. Forty Sprague-Dawley male rats were divided into 4 groups, then administered orally with 450, 900, 1,800 mg/kgBW of CA aqueous extract and 10 ml/kgBW distilled water as control. Observation on the liver histopathology and the levels of aspartate aminotransferase (AST) also alanine aminotransferase (ALT) in the blood indicated that there was a relationship between the dose and toxic response of CA aqueous extract on repeated administration during 15 days treatment in rats. Level of toxicity rose from congestion, steatosis, to cell necrosis. Dose of 1,800 mg/kgBW potentially led to necrosis of liver cells of rats.

GROWTH RESPONSE OF NANNOCHLOROPSIS AT OUTDOOR CULTIVATION IN MEDIUM WITH VARIATION OF NITROGEN CONCENTRATION Astuti, J. Tri; Sriwuryandari, Lies; Yusiasih, Retno; Sembiring, Tarzan
Teknologi Indonesia Vol 33, No 2 (2010)
Publisher : LIPI Press

Micro-algae are fast-growing unicellular photosynthetic microorganisms that able to fi x CO2 while capturing solar energy. Source and concentration of nitrogen itself affected to the growth character and composition of microalgae. Cultivation with limited of nitrogen resulted great increase in the lipid content. This study was conducted to investigate the infl uence of nitrogen concentration to the growth rate and lipid characteristics of Nannochloropsis sp. In this study, ammonium nitrate (NH4NO3) was added in different concentration, i.e. 0; 30; 70; and 100% based on nitrogen content in f/2 medium, or equivalent to 0; 1.06; 2.47; and 3.53 (10-4 M). All treatment was prepared triplicate, then cultivated at outdoor batch culture systems and aerated continuously with a sterilized of atmospheric air. The algae biomass was harvested at 14th day after inoculated and then analyzed. Data showed that Nannochloropsis sp. could be cultivated in the outdoor batch system, which temperature was in the range of 26.1137.97oC, with average of 33.44oC. Compared to its initial condition, pH culture increased signifi cantly from 6.92 to 8.54. The highest OD680nm (0.500) and dry cell concentration (458mg.L-1) was obtained by using NH4NO3 at 2.47x10-4 M. The lipid content was 63.58% and 46.59% of dry cell weight when using nitrogen 1.06x 10-4M and 2.47x10-4M, respectively. Composition of fatty acid was not signifi cantly affected by the changing of nitrogen concentration. Palmitic acid (C16:0) was the most of fatty acid in Nannochloropsis sp. (44.4753.97%), followed by lauric acid (25.7834.34%), and myrictic acid (19.0721.19%). The using of N-NH4NO3 at 2.47x10-4M gave the highest lipid content of 213.15mg.L-1.

ENZYMATIC HYDROLYSIS OF THE FEC 25 AND ROTI CASSAVA STARCH (Manihot esculenta) VARIETIES BY α-AMYLASE FROM A MARINE BACTERIUM (BREVIBACTERIUM SP.) rahmani, nanik; Andriani, Ade; Hartati, Sri; Yopi, Yopi
Teknologi Indonesia Vol 39, No 3 (2016)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v39i3.295

Cassava (Manihot esculenta) is one of the food sources that is familiar for Indonesian society. Carbohydrates of cassava can be enzymatically hydrolyzed into small oligosaccharides that can be used as a material for functional food components production. Starch from the FEC 25 and roti cassava starch have been hydrolyzed by α-amylase from marine bacterium, Brevibacterium sp. for maltooligosaccharides production. The best hydrolysis reaction condition of the FEC 25 cassava starch were starch concentration of 6.0% (w/v), the ratio of α-amylase and starch 1:1, 50 mM of sodium phosphate buffer pH 6.6, the reaction temperature at room temperature (30oC) and the reaction time of 8 hours with the highest reducing sugar value of 21.675 ppm. While the best hydrolysis of the Roti cassava starch were starch concentration of 6% (w/v), the ratio of α-amylase and starch 1:1, 50 mM of sodium phosphate buffer pH 6.6 and the reaction temperature at 50oC, the reaction time of 8 hours with the highest reducing sugar value of 13.278 ppm. The results of maltooligosaccharides analysis using thin layer chromatography (TLC) showed that the type of maltooligosaccharides formed on hydrolysis the FEC 25 cassava starch are glucose, maltose and maltotriosa, while Roti cassava starch are glucose, maltose, maltotriose, and maltopentaose. The formation of maltooligosaccharides showed that both of cassava starch can be hydrolyzed by α-amylase from marine bacterium Brevibacterium sp.

THE INTERACTION BETWEEN GLOBAL CLIMATE CHANGE AND TROPICAL FOREST ECOSYSTEMS Rozak, Andes Hamuraby
Teknologi Indonesia Vol 36, No 1 (2013)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v36i1.198

In the last 100 years, the global mean temperature has increased approximately 0.6oC and is predicted to increase approximately 1.1oC to 6.4oC in the end of 21st century. On the other hand, deforestation still continues with the rate of -5.2 million hectares per year. This global climate change phenomenon in physical dimension has been analyzed in detail; yet its effect to the changes of biodiversity particularly in tropical forest ecosystems is still poorly understood. From the literature review, it is clear that there is correlation between global climate change and tropical forest ecosystems. The effect of climate change to forest ecosystems itself includes species range shifts, species extinction risks, biome shifts, and biogeochemical cycling. Furthermore, the deforestation of tropical forestecosystems also has reverse effects to the global climate change, i.e. is increasing the amount of green house gasses which directly changes the three climatic variables which are the Earth surface temperature, the total precipitation, and the atmospheric moisture convergence.

PERFORMANCE OF MICROWAVE PRETREATMENT ON ENZYMATIC AND MICROWAVE HYDROLYSIS OF BETUNG BAMBOO (Dendrocalamus asper) Fatriasari, Widya; Syafii, Wasrin; Wistara, Nyoman; Syamsu, Khaswar; Prasetya, Bambang
Teknologi Indonesia Vol 37, No 3 (2014)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v37i3.232

In this present study, we focused on how the changes in the best microwave pretreatment affected the performance of enzymatic and microwave hydrolysis of pretreated bamboo. This solid fraction was subjected to enzymatic hydrolysis following NRE L protocol and microwave acid-hydrolysis with/without presence of activated carbon (0.5 g/g) at 1% and 5% of sulfuric acid concentration for 512.5 m at 330 watt. Short duration microwave-acid hydrolysis of microwave pretreated bamboo showed better reducing sugar yield than that of enzymatic one. Microwave heating for 12.5 inm at 330 W hydrolyzed with 1% acid using microwave irradiation demonstrated a high reducing sugar yield (25.81% of dry biomass or 27.12% of dry substrate). In this treatment, 37.92% of hollocellulose can be converted into reducing sugar or equivalent to 36.12% of maximum potential sugar released. This yield was increased 6.09 times compared to the highest reducing sugar yield coming from enzymatic hydrolysis using 20 FPU/g of cellulase enzymes. Reducing sugar yield obtained with 5% microwave acid hydrolysis of microwave pretreatment for 5 m at 770 W was equal to the result of hydrolysis for 12.5 m at 330 W. Unfortunately, the activated carbon as solid catalyst in microwave hydrolysis could only reduce brown compound without reducing sugar yield improvement.

VARIASI SUHU MUKA LAUT BULANAN BERDASARKAN KANDUNGAN KIMIA KORAL Cahyarini, Sri Yudawati; Pfeiffer, Miriam; Prayudi, Dudi
Teknologi Indonesia Vol 32, No 2 (2009)
Publisher : LIPI Press

Information on environmental changes which is available today is limited to only dozen years back. In order to make an assesment on environmental changes, information on longer time is required. Corals can provide environmental data till thousand years back. To have some information, it is required to analyze geochemical proxy. By analyzing geochemical elements such as Sr/Ca, ?18O, sea surface temperature and salinity can be reconstructed. Further, by analyzing and interpreting time series data of coral geochemical proxy can be used to understand intensity, process, and mechanism of the environmental damage. In this study, reconstruction of sea surface temperature using Sr/Ca and ?18O coral from Timor is used as a case. The result shows that Sr/Ca is influenced by sea surface temperature.

THE EFFECT OF ZnO ADDITIVE ON PHYSICAL PROPERTIES AND MICROSTRUCTURE OF BaFe12O19 MAGNETIC MATERIAL Sebayang, Perdamean; Sudiro, Toto; Aryanto, Didik; Nugraha, Endra
Teknologi Indonesia Vol 39, No 2 (2016)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v39i2.265

Preparation of BaFe 12 O 19 powder containing varying amount of ZnO as 5, 10, 15 and 20 % by mass were prepared by a high energy milling (HEM) for 1 hour and compacted into a pellet using 80 kgf/cm 2 in compressive pressure. The samples were sintered at elevated temperatures of 800 and 1,000 o C for 2 hours, separately. The characterization results indicated that BaFe 12 O 19 -10 mass % ZnO exhibits excellent in physical and magnetic properties that can be potentially used for recording media and microwave absorbing material applications.

PENGOLAHAN BAN BEKAS BERWAWASAN LINGKUNGAN MENJADI BAHAN BAMPER PADA OUTOMOTIF Bukit, Nurdin; Frida, Erna
Teknologi Indonesia Vol 34 (2011)
Publisher : LIPI Press

On the minimizing of waste tires which can damage the environment can be done by processing waste tires into powder waste tires and used as a fi ller in the manufacture of thermoplastic elastomer composite which can be used as bumpers on automotive. The Research has been done by mixing the powder waste tires, SIR-20 compound and polypropylene,with Polipropilena Maleic anhydride compatibilizer. Preparation of raw materials is done by making rubber compound with two roll mill mixing equipment. Composite made by blending process at temperature of 180C with a speed of 60 rpm in an internal mixer, with composition (30, 40, 50)% weight and size of 1mm and 60 mesh, composite results in a granular form in the molding hot press, cold, then made in to specimens for each test sample in accordance with JIS K 6781 standard size for tensile test. The Results obtained from mechanical test properties waste tires size 60 mesh powder better than the size of 1mm. The best mechanical properties obtained on the composition of 50% with a maximum of 13 MPa tensile strength and elongation at break 148%. The result of SEM analysis of morphology 60 mesh size is more than homogeneous than 1mm.

Investigation of Hydrogen Flow Uniformity in a Serpentine Separator Plate of a PEMFC Using Computational Fluid Dynamics Simulation Wahyu, Haifa; Oemry, Achiar; Djunaedi, Imam
Teknologi Indonesia Vol 35, No 3 (2012)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v35i3.189

This paper presents an investigation on the uniformity of hydrogen flow in a separator plate of a Polymer Electrolyte Membrane Fuel Cell (PEMFC). Hydrogen is the main reactant of a PEMFC that fl ows within the separatorplate and into the MEA. Separator plates have fl ow fi eld lay out which is the determining factor for the uniform distribution of the gas. The separator plates used in this study has the shape of serpentine fl ow fi eld, taken from a 200 Watt PEMFC stack. The fl ow of hydrogen gas is simulated within the separator plate to analyse the pressure and velocity distribution which has a correlation with the fl ow fi eld design. The objective of the study is to determine flow uniformity within the separator plates by increasing the hydrogen gas pressure from 1 bar up to 3 bars. Although flow distributions for the three cases are similar and quite uniform, but the velocity in the plates was reduced when the hydrogen pressure was increased. This is due to the backpressure occurs as a result of resistance from the flow field and also the gas diffusion layer governing a fuel cell. From the experiments on the characterization of fuel cell stack, the best practice is to maintain the inlet pressure at low level, that is around 1 bar, which is in agreement with the current simulation results. The fl ow was simulated using commercial CFD package by employing Navier-Stokes method which is the governing equation of the computational fl uid dynamics (CFD) application. The results are compared to the steady output without random differences of an experimental running of the fuel cell stack.

Page 13 of 17 | Total Record : 163

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