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INDONESIA
Teknologi Indonesia
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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MECHANICAL AND MAGNETIC PROPERTIES OF BONDED MAGNET Nd2Fe14B PRODUCED USING BINDER BAKELITE Muljadi, -; Sardjono, Priyo; Sebayang, Perdamean
Teknologi Indonesia Vol 37, No 3 (2014)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v37i3.231

Abstract

Bonded magnet Nd2Fe14B was made with mixing Nd2Fe14B powder and polymer bakelite using compressing method. The bakelite concentration was varied of 5 wt%, 10 wt%, 15 wt%, and 20 wt%. Both Nd2Fe14B and bakelite powders were mixed and milled for 24 hours using a ball mill. The powder was formed by dry pressing and subsequently dried in a drying cabinet at a temperature of 180oC for 4 hours. Then, magnetization process was done using impulse magnetizer, and performed measurements of the magnetic properties such as flux density, remanenceBr, coercivity Hic and energy density (BH)max using Gaussmeter and hysteresis permeagraph. Characterization of mechanical properties such as bending strength (BS) and vickers hardness (Hv) was determined before magnetization. Bakelite concentration had a significant influence on both magnetic and mechanical properties. From the characterization results, the optimum concentration of bakelite was 10% and 15% wt. Bonded Nd2Fe14B magnet obtained had the following properties: BS value of 27.7433.42 MPa, Hv value of 292.65314.33 MPa, the value of the magnetic flux density from 1360 to 1400 Gauss, remanence Br = 4.995:02 kG, coercivity Hic = 7.8 kOe, and energy density (BH)max about 5.13 to 5.24 MGOe at the optimum concentration.
PEMBUATAN NANOPAR TIKEL LixMn2O4 Wigayati, Etty Marti
Teknologi Indonesia Vol 32, No 2 (2009)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v32i2.10

Abstract

LixMn2O4 nanoparticle has been prepared using Li2CO3 and MnO2 as starting materials. Firstly, Li2CO3 and MnO2 were mixed using solid state reaction, then the powder was calcinated at 700oC and sintered at 800oC. The resulted pouder was characterized using SEM, XRD, and EIS (Electrochemical Impedance Spectroscopy). Henceforth, LixMn2O4 powder was processed into nanoparticle size through milling process using PBM (Planetary Ball Milling) for 80 hour and ultrasonificator with power of 300 watt for 2 hour. The characterization was conducted again using SEM, XRD, PSA and EIS. The result shows that there is no diffraction pattern change after the milling process. Examination using SEM shows particle changes from needles to round shapes with smaller sizes. Diffraction analyzes using Rietveld method results in lattice parameter of 8.23454 , cell unit volume of 558.3647 3 and the crystal structure is cubic with space group of Fd-3m. The particle size of the final product is analyzed using Particle Size Analyzer (PSA) which results in the value of 178 nm in average diameter. The measurement of electrical impedance gives values of 2 M ohm (before milling) and 8 M ohm (after milling).
EFFECT OF WET MILLING TIME OF Nd-Fe-B FLAKES MATERIALS ON PARTICLE SIZE, MICROSTRUCTURE, AND MAGNETIC PROPERTIES Sardjono, Prijo; Muljadi, Muljadi; Suprapedi, Suprapedi; Djauhari, Nenen Rusnaeni
Teknologi Indonesia Vol 39, No 2 (2016)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (16.054 KB) | DOI: 10.14203/jti.v39i2.292

Abstract

The refining of Nd-Fe-B alloy flakes has been done by a wet mechanical milling method using a ball mill. This process is used to produce a fine powder for making permanent magnet materials. The variation of milling time was 16, 24, 48 and 72 hours and a milling medium was used a toluene (pa- Emerck)) to protect the particle from oxidation during the milling process. After milling processes, the samples' distribution particle size were measured by using Particle Size Analyzer (PSA). Microstructure analysis has been conducted by using X-ray diffractometer (XRD) and Scanning Electron Microscope (SEM/EDX) for samples after and before milling. Vibrating Sample Magnetometer (VSM) was used to measure magnetic properties. The characterization results show that the refining process with the wet ball mill obtained finest powder with average size about 1.49 μm for milling time of 48 hours. According to SEM/EDX and XRD analysis, it shows that the crystal structure of the sample before milling was different compared to the sample after milling. It is found new magnetic phase with formula Nd2 Fe14 B. The magnetic properties of sample after milling 48 hrs is higher than that of sample before milling.
SCREENING OF NITRILE-DEGARADING ENDOPHYTIC BACTERIA FROM THE BIODIVERSITY OF INDONESIA Atmosukarto, Ines I. C.; Sunarko, Bambang
Teknologi Indonesia Vol 34 (2011)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v34iKhusus.47

Abstract

Nitriles are an important group of compounds which appear in the environment via natural or industrial synthesis. Nitrile-metabolising microorganisms usually convert nitriles via one of the following two hydrolytic pathways: 1) conversion of the nitrile directly to its corresponding carboxylic acid and ammonia by nitrilase, and/or 2) conversion of the nitrile by nitrile hydratase to an intermediate amide, which is then converted by an amidase to the corresponding carboxylic acid and ammonia. The potential biotechnological application of these enzymes to produce amides and/or acids from nitriles has a major industrial interest. Higher plants are host to microorganisms, generally referred to as endophytic microbes (or endophytes) which colonise the internal tissue of living plants without causing overt negative effects to their host. Rare and biologically active compounds have been isolated from these microbes ranging from anti-infective activity, antioxidant, anticancer, insecticidal and others. Some of the compounds that have been discovered in endophytic microbes include taxol, cryptocin, cryptocandin, and ambuic acid amongst a few. However, the potential of this relatively untapped source of microbial diversity as a source of nitrile converting enzymes has yet to be evaluated. In this study we have tested approximately 850 bacterial endophytes for their ability to utilize acetonitrile (aliphatic nitrile) and benzonitrile (aromatic nitrile) as a sole source of energy, carbon and nitrogen for their growth. Based on their growth pattern, 97 isolates of those were able to utilize acetonitrile, of which 7 could also utilise benzonitrile. This result suggests that those isolates are likely to possess enzymes which are able to convert nitriles as indicated by the presence of metabolic byproducts such as carboxylic acid and ammonia. This is to our knowledge the first report of such activity for endophytic bacteria.
Design and Analysis of the Prototype of Pico Hydro Scale Submersible Type Turbine-Generator for Flat Flow River Application Subekti, Ridwan Arief; Susatyo, Anjar; Irasari, Pudji
Teknologi Indonesia Vol 35, No 3 (2012)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v35i3.188

Abstract

This paper discusses the design and analysis of prototype of submersible type turbine-generator for fl at fl ow river application. 500 W pico hydro turbine with the net head of 1 m was used. The type of turbine used was ofPropeller type with the blade profi le shape of airfoil NACA 6412 and the runner blade number of 6 pieces. Turbine and generator was aligned on one shaft (direct coupled) so that the construction was simple. The generator usedwas of permanent magnet generator type of 500 W, 500 rpm, 1 phase, 50Hz, 220 V. The turbine-generator unit was then tested in one of Kebun Raya Cibodas channels. The test was conducted at varied heads and constant loadscomprised of 5 x 100 W lights. The test results presented in the form of head vs. speed and head vs. power graphs show that the system could only have effi ciency of 19.98%.
PRELIMINARY STUDY OF PYROLYSIS OF CACAO POD HUSKS AND PRODUCT YIELDS IDENTIFICATION Mansur, Dieni
Teknologi Indonesia Vol 37, No 2 (2014)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (16.051 KB) | DOI: 10.14203/jti.v37i2.221

Abstract

Pyrolysis of cacao pod husks as one of agricultural crop residue took place in a fixed bed type of pyrolyzer under atmospheric pressure at 500oC. The process was studied by varying methods and temperature of feeding.The effect of N2 flow rate as carrier gas was also investigated. These effects influenced yield of product after pyrolysis especially on the char. Char as the main product of pyrolysis was recovered as 70 C mol% with one step feeding at 25oC under 20 ml/min of N2. Pyrolysis of cacao pod husk also produced bio-oil that consisted of several chemical compounds such as aliphatic and cyclic ketones, carboxylic acids, furans, aldehydes, alcohols, phenols and heterocyclic aromatics.
Anatomical and Physiological Characteristics of Reclamation Plant on the Post-Mining Land in Riding Panjang, Bangka Nurtjahya, Eddy; Juairiah, Lina
Teknologi Indonesia Vol 35, No 3 (2012)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v35i3.268

Abstract

Tin mining leaves disturbed land with sandy texture, damages natural drainage and habitats, and very low water holding capacity. The enrichment of species selection criteria for revegetating tin tailing with anatomical and physiological characters is needed to facilitate decision maker to select local species suitable for revegetation and to meet the economical need of the local people in post tin mining era. Besides exotic species, a handful of local tree species was planted recently. The need of more local species is especially needed to support biodiversity in mined land. Study of some leaf anatomical and root physiological characters of twelve months seedlings of leban(Vitex pinnata L-Verbenaceae) and ubak (Syzygium grande (Wight) Walp.Myrtaceae) planted in unmined land and tin-mined land in Bangka Island was conducted using wholemount and paraffi n methods. The fi ndings showedthat anatomical and physiological parameters of V. pinnata are more signifi cant than those of S. grande. Therefore, V. pinnata is more adaptive grown on tin tailing than S. grande.
PENGARUH KOMPOSISI BAHAN TERHADAP KARAKTERISASI BRIKET LIMBAH BIJI JARAK PAGAR (JATROPHA CURCAS LINN) Sriharti, -; Salim, Takiyah
Teknologi Indonesia Vol 34 (2011)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v34iKhusus.38

Abstract

An experiment on the infl uence of material composition to the characteristic of the briquette jatropha seed waste (Jatropha curcas Linn) has been done. The material consist of jatropha seed waste, rice husk, jatropha seed shell waste and coconut shell. The methods of briquette processing were conducted with carbonization and pressing with hydraulic manual system with capacity of 16 briquette per batch. The result of chemical characteristics of jatropha briquette shows that moisture content, calorie value, fulfi ls the Indonesian National Standards (SNI) number 01-6235-2000, whereas ash content does not fulfi ls the SNI. The result of experiment showed that physical characteristics of jatropha briquette including initial and relaxation density fulfi ls the SNI. The composition of material jatropha seed waste with coconut shell showed the best result with combustion rate of 18.61 gram/minute, specifi c consumtion of fuel 0.0997 gram fuel/gram water, combustion power 161.961 watt and thermal effi ciency 74.27 %.
SUBSTITUTION COMPONENT CULTIVATION MEDIA OF PHOTO-FERMENTATION PROCESS FOR LOW COST HYDROGEN GAS BIOPRODUCTION Susilaningsih, Dwi -; Uhtiza, Tami Astie; Anam, Khairul -
Teknologi Indonesia Vol 40, No 2 (2017)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (359.597 KB) | DOI: 10.14203/jti.v40i2.378

Abstract

Employing the Rhodobium marinum bacteria as an agent of hydrogen bioproduction with facultative fermentation condition needs two steps of cultivations, i.e., pre-culture and hydrogen production periods with different media.  The two steps cultivation is important state for hydrogen gas production rate. ASY (Ammonium, Succinate, and Yeast extract) is usually used as standard medium in biohydrogen production and mostly the component is analytical grade of chemicals. Series of cultivation media substitution by combining ASY with other cost-effective chemicals were investigated. The total of sixteen combinations of media were observed (P0-P15). Cultivation condition of R. marinum was set in an illuminated light of 31.17 µmol s-1m-2photon and agitated in shaker of 120 rpm for nine days. The experiment was designed as random selection with anova analyses. The results exhibited that P7 medium combination released the highest hydrogen gas of 61.29±0.52 ml/80 ml media among the others combination media. Using one-way ANOVA, there was a statistically significant difference between the mean number and condition and it was found P7 was significantly different with the others combination media, except P7 was insignificantly different with P3 only. Overall, the combination media is cheaper than the ASY medium. The ASY medium price is about USD 677, and the substitution media prices were ranging from USD 4.24 to USD 613.47. However, the further research on optimisation cultivation condition is needed.
AKTIVITAS INHIBISI ?-GLUKOSIDASE GRANULAR TEH HIJAU (Camellia sinensis) GRADE Arraca Yabukita HASIL DIAFILTRASI MENGGUNAKAN MEMBRAN NANOFILTRASI Widiyarti, Galuh; Susilowati, Agustine; Aspiyanto, -
Teknologi Indonesia Vol 35, No 1 (2012)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v35i1.176

Abstract

The activity of ?-glucosidase inhibition test of local granular green tea (Camellia sinensis) grade of Arraca Yabukita has been done. Granular green tea obtained by vacuum drying of the concentrate of the diafiltration process using nanofiltration membrane (DF-NF) at 50C for 0-80 hours. Every 8 hours of drying time, the analysis of water content, total polyphenols, and ?-glucosidase inhibitory activity of granular green tea were conducted. The?-glucosidase inhibitory activity test was performed by by Kim Yong-Mu method and compared to quercetin as standard. The results showed that, the drying process increases the ?-glucosidase inhibitory activity of granular green tea. At the optimum drying time 72 hours, the ?-glucosidase inhibitory activity of granular green tea is about 18 times higher than quercetin.

Page 10 of 17 | Total Record : 163

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