Makara Journal of Science
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KOMPAKTIBILITAS KOMPOSIT ISOTROPIK Al/Al2O3 DENGAN VARIABEL WAKTU TAHAN SINTER
No full textCompactibility of Al/Al2O3 Isotropic Composite with Variation of Holding Time Sintering. The requirement of component with structural ability, light weight and also strength is increasing base on Metal Matrix Composites (MMCs) by aluminum as matrix (AMCs). A structural ability is connected to composites compactibility which is depend on quality of interfacial bounding. Powder metallurgy is one of method to produce composite with powder mixing, compacting and sintering. Volume fractions reinforced and sintering time can influence composites compactibility. Volume fractions reinforced variable can produce different reinforcement effect. Beside that, on sintering enables the formation of new phase during sintering time. In this research, Al/Al2O3 isotropic composites are made with aluminum as matrix and alumina (Al2O3) as reinforced. Volume fraction reinforced used 10%. 20%. 30% and 40%. Sintering temperature and compaction pressure are each 600oC and 15 kN. The tests that applied are compression and metallographic test. The result that obtained is optimum compactibility of Al/Al2O3 composite reached at holding time 2 hour. During sintering, new phase can occur that is aluminum oxides (alumina), with unstable properties. The best volume fraction reinforced and holding time sintering are 40% and 2 hours. Key words: MMCs, compactibiliy, holding time sintering, powder metallurg
ADSORPTION OF WATER AND BENZENE VAPOUR IN MESOPOROUS MATERIALS
No full textMesoporous materials have attracted the attention of many researchers due to the potential applications promised by the materials. This article discusses adsorption of water and benzene vapour in mesoporous materials (mesoporous silica: MCM-41, MCM-48 and their modification). MCM-41 and MCM-48 were synthesized hydrothermally at 100°C using cethyltrimethylammonium chloride or dodecyltrimethylammonium bromide for MCM-41 (C16) or MCM-41 (C12) respectively and a mixture of cethyltrimethylammonium bromide and Triton X-100 for MCM-48 as templates. Their modifications were conducted by silylation of MCM-41 (C16) and MCM-48 with trimethylchloro silane (MCM16- TMCS and MCM48-TMCS) and t-butyldimethylchloro silane (MCM16-TBDMCS and MCM48-TBDMCS). Results showed that MCM-41 and MCM-48 materials had hydrophobic features which were shown in the small amount of water adsorption at low P/P0. The hydrophobicity of samples used in this study decrease in the sequence: MCM-41 (C16) > MCM-48 > MCM-41 (C12). The hydrophobicity increased when MCM-41 and MCM-48 were silylated with TMCS or TBDMCS. All unsilylated MCM materials show higher affinity to benzene at low P/P0 than the silylated samples. The results of water and benzene adsorption showed that silylated samples are promising candidates as selective adsorbents for organic compounds. Keywords: Adsorption, water, benzene, MCM-41, MCM-4
PERLUASAN METODE MFCC 1D KE 2D SEBAGAI ESKTRAKSI CIRI PADA SISTEM IDENTIFIKASI PEMBICARA MENGGUNAKAN HIDDEN MARKOV MODEL (HMM)
No full textIn this paper, we introduce an extension of Mel-Frequency Cepstrum Coefficients (1D-MFCC) methodology to bispectrum data, referred to as 2D-MFCC, for feature extraction. 2D-MFCC is based on 2D bispectrum data rather than 1D spectrum vector yielded by Fourier transform, so the filter in 1D-MFCC must be extend to 2D filter and using 2D cosine transform to get the mel-cepstrum coefficients from the filtered bispectrum values. Based on 2D-MFCC, we develop a speaker recognition system with Hidden Markov Model (HMM) as classifier. The experimental results show that the recognition rate is around 88%, 92% and 99% for 20, 40 and 60 data training, respectively.  
KOMUNITAS ZOOPLANKTON DI PERAIRAN WADUK KRENCENG, CILEGON, BANTEN
No full textZooplankton communities in the Krenceng Reservoair, Cilegon, Banten. This research was carried out to know the structure of zooplankton communities and relations between the phytoplankton and zooplankton in the Krenceng Reservoair, Cilegon. The zooplankton abundance with used Sedwigck Rafter Counting Method, diversity and evenness were counted. Relations between zooplankton and the environmental factors as well as its relations to phytoplankton calculated with regression. The results showed that are 13 species of the zooplankton found which including in three classes with the highest abundance on Novembers 2002 and March 2003 of the Rotifera. The analysis of regression pointed out that the environmental factors such: pH, BOD5, nitrate, CO2 and abundance of phytoplankton influence the abundance zooplankton in November. While in March, the abundance of zooplankton is influenced by brigthtness, nitrate, orthophosphates and C organic. The abundance of phytoplankton influenced positively by the abundance of zooplankton. Keywords: Banten, Komunitas, Waduk Krenceng, Zooplankto
PENGEMBANGAN PERANGKAT LUNAK SIMULASI KOMPUTER SEBAGAI ALAT BANTU DALAM ANALISIS FARMAKOKINETIK
No full textThe Development of a Computer Simulation Software as a Tool in Pharmacokinetics Analisys. This research uses mammilary model (one compartment and two compartments) as compartment model in which a single drug administration is given via oral and intravenous. Mathematical modeling in differential equations can be derived from a pharmacokinetics model. The solutions are pharmacokinetics variables and parameters that can be solved using some mathematical and numerical methods such as Laplace transformation, residual method, superposition principle, trapezoidal rule and some solving methods in differential equations.To overcome manual calculation and to visualize a drug’s dynamics in the graph form, a computer simulation software based on Visual Basic has been built. The simulation results show that any particular sample data plasma can be checked whether it is given orally or injection and has a tendency to be compatible with an assumption of one compartment or two compartments. For urin data, the software capability is still limited only for one compartment. However, it can checked if the corresponding data is given via oral or injection. So the simulations show that pharmacokinetics variables and parameters will have individual effects. Keywords: pharmacokinetics, mammilary model, pharmacokinetics model, residual metho
Studi Spektroskopi Electron Spin Resonance (Esr) Lapisan Tipis Amorf Silikon Karbon (A-Sic:H) Hasil Deposisi Metode Dc Sputtering
No full textThe dangling bond defect density in sputtered amorphous silicon carbon alloys have been studied by electron spin resonance (ESR). The results show that the spin density decreased slightly with increasing methane fl ow rate (CH4). The infl uence of carbon and hydrogen incorporation on g-value revealed that for CH4 fl ow rate up to 8 sccm, the ESR signal is dominated by defects characteristic of a-Si:H fi lms and for CH4 fl ow rate higher than 8 sccm the g-value decreased towards those usually found in a-C:H fi lms. Infrared (IR) results suggest that as CH4 fl ow rate increases more carbon and hydrogen is incorporated into the fi lms to form Si-H, Si-C and C-H bonds. A direct relation between the IR results and the defect density and g-value is observed.Keywords: Electron spin resonance, silicon carbon, defect density, sputterin
STUDI DISORDER LAPISAN TIPIS AMORF SILIKON KARBON (a-SiC:H) HASIL DEPOSISI METODE DC SPUTTERING
No full textDisorder Study of Amorphous Silicon Carbon (a-SiC:H) Films Deposited by DC Sputtering Method. Disorder amorphous network of amorphous silicon carbon (a-SiC:H) films has been investigated for films prepared by dc sputtering method. The films were deposited using silicon target in argon and methane gas mixtures. The optical absorption coefficients have been performed by UV-VIS (ultra violet-visible) reflectance and transmittance spectroscopy. Disorder parameter has been obtained from the optical absorption coefficient α (E) using Tauc plot. Increasing methane flow rate has an effect on increasing Tauc gap and decreasing disorder parameter. The amorphous network of the films tends to be more disorder with increasing methane flow rate. The relation of disorder amorphous network with structural and compositional properties will be discussed.Keywords: Disorder, amorphous silicon carbon, sputtering, structural properties, infrare
THE NEW VARIANT OF THE SANDMEYER MODIFICATION REACTION BY IN-SITU GENERATED FORMALDEHYDE: SEMI-SYNTHESIS OF VANILLIN FROM GUAIACOL
No full textIthas been carried out the modification of Sandmeyer modification reaction by in-situ generated formaldehyde. The insitu generated formaldehyde has been performed via heterogeneous phase reaction between 6.40 mL (0.10 mol) CH2Cl2 as organic phase with 40 mL 6.0 N KOH-alcoholic solution as aqueous phase and 2.56 g tetrabutylammoniumperchlorate as phase transfer catalyst (PTC) by 40o C for 4 hours. Furthermore, 5.9 mL (0.05 mol) guaiacol 1 is dropwised to add to the reaction mixture. After the addition of guaiacol 1 finished, then reaction is allowed to run for 1 hour, so that the white crystal of vanillil alcohol 10 can be produced in 25.3%. Followed by oxidation of vanillil alcohol 10 with mixture of K2Cr2O7/conc. H2SO4 solution as oxidator, and 18-crown ether-6 as phase transfer catalyst (PTC) in heterogeneous phase at the room temperature for 5 hours, can be afforded vanillin 4 in 6.2% (calculated from starting material 1).Keywords: Guaicol, sandmeyer reaction, formaldehyde, vanilli
EFEK ESTROGENIK EKSTRAK ETANOL 70% KUNYIT (Curcuma domestica VAL.) TERHADAP MENCIT (Mus musculus L.) BETINA YANG DIOVARIEKTOMI
No full textEstrogenic Effect of 70% Ethanol Turmeric (Curcuma domestica Val.) extract on ovariectomized Female Mice (Mus musculus L.). The influence of extract turmeric (Curcuma domestica Val.) on endometrium thickness, vaginal epithelium, mammary gland, and protein of estrogen receptor of ovariectomized mice was examined. Twenty five ovariectomized mice which were divided into five groups, were treated by ethynilestradiol (8,4 x 10-3 g), aquades (10 ml), and turmeric extract at doses 230 mg/kg b.w.; 310 mg/kg b.w.; and 390 mg/kg b.w. for eight days. At the end of experiments the mice were killed, then the uterus, vagina, and mammae were removed and the wet weight of uterus was recorded. Uterus, vagina, and mammae were examined histologically. Estrogen receptor protein from uterus were analized by using SDS-PAGE. One way anava test showed that turmeric extract at doses 310 mg/kg b.w. and 390 mg/kg b.w give estrogenic effect on vaginal ephitelium, endometrium thickness, and diametre of mammary glands. SDS-PAGE analysis showed there were differences in protein concentration between control and treatment groups which were seen in the thickness of the bands. Estrogen receptor band could be detected in sampel of treatment groups at molecular weight 45 kDa. Keywords: Curcuma domestica Val., estrogen, ovariectomy, Mus musculus L
HYDROCARBON DEGRADING BACTERIA: ISOLATION AND IDENTIFICATION
No full textThere is little information how to identify hydrocarbon degrading bacteria for bioremediation of marine oil spills. We have used gravel which contaminated oil mousse from Beach Simulator Tank, in Marine Biotechnology Institute, Kamaishi, Japan, and grown on enrichment culture. Biostimulation with nutrients (N and P) was done to analyze biodegradation of hydrocarbon compounds: Naphthalene, Phenanthrene, Trichlorodibenzofuran and Benzo[a]pyrene. Community of bacteria from enrichment culture was determined by DGGE. Isolating and screening the bacteria on inorganic medium contain hydrocarbon compounds and determination of bacteria by DAPI (number of cells) and CFU. DNA was extracted from colonies of bacteria and sequence determination of the 16S rDNA was amplified by primers U515f and U1492r. Twenty nine strains had been sequence and have similarity about 90-99% to their closest taxa by homology Blast search and few of them have suspected as new species. Keywords: Isolation, Identification, Biostimulation, Extraction, Sequence, DGG