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INDONESIA
Jurnal Matematika & Sains
Published by Institut Teknologi Bandung
ISSN : -     EISSN : -     DOI : -
Core Subject : Education,
Mathematics
Arjuna Subject : -
Articles 339 Documents
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Penentuan Energi Kisi Oksida-Oksida Piroklor Dede Suhendar; Ismunandar Ismunandar
Jurnal Matematika & Sains Vol 11, No 1 (2006)
Publisher : Institut Teknologi Bandung

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Abstract

Lattice energy of pyrochlore oxides prediction is important in relation with the synthesis effort. This work was aimed to find an equation that could be used to predict the lattice enthalpy of pyrochlore oxides. As standards, pyrochlores with known enthalpy formation were used to calculate the lattice entalphy via Born Haber cycle U(BHC). Lattice energies, U, of pyrochlore oxides were calculated by Glasser (G), Glasser-Jenkins, (GJ), and Yoder-Flora, (YF) equations. Plotting of Born-Haber lattice energies U(BHC) vs. U(G), U(GJ), and U(YF) resulted in R2 = 0.9564, 0.8671, and 0.9993, respectively. Based on the fitting of U(BHC) vs. U(YF), then a combination of Yoder-Flora and Kapustinskii equations were formulated and tested for U(BHC) of pyrochlore oxides. The Yoder-Flora-Kapustinskii (YFK) equation was U(YFK)pyrochlore = Σ U(K) oxide of A + Σ U (K) oxide of B where U(K) is lattice energy of oxide calculated by Kapustinskii equation using ionic radii of A in eight coordination number, and B in six coordination number, except for B ions from oxide fluorite structures in eight coordination number. The differences between U(YFK) and U(BHC) were < 3 %..
Evaluation of the Ethylene Effect on Well Defined Copper Enzymes Megawati Santoso; Harold M. Goff
Jurnal Matematika & Sains Vol 11, No 1 (2006)
Publisher : Institut Teknologi Bandung

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An indirect approach in studying ethylene binding sites of copper enzymes was carried out since ethylene pleitropic effect in plants and the general affinity of Cu(I) complexes for ethylene suggest a possibility of ethylene binding to various copper enzymes. For this purpose, superoxide dismutase (SOD) and tyrosinase were evaluated using two different methods. H-NMR spectra of three different conditions of SOD (native SOD; reduced SOD; and reduced SOD in the presence of ethylene) were acquired at 25 °C. Activity of mushroom tyrosinase was monitored in the absence of ethylene by evaluating the formation of dopachrome at 475 nm. Three other assay systems were constructed the same way as the control, except one of the reagents (enzyme, DL-DOPA, or sodium phosphate buffer) was each saturated with ethylene prior to mixing all of reagents. Both systems behaved unsatisfactorily for the purpose of evaluation. The coordinated ethylene proton-NMR signal was obscured by the broad HOD signal, due to the partial oxidation of Cu(I) SOD by trace oxygen. Nonetheless, the tyrosinase assay results demonstrated that displacement of oxygen in the assay system by ethylene did not account for the loss of activity. The observed ethylene effect on tyrosinase activity, however, was minimal, since ethylene could produce threshold physiological response at concentration of 6.5 x 10-9 M.
Lanthanum (III) Selective Electrode Based on 1,10-Diaza-4,7, 13,16-Tetraoxacyclooctadecane-N,N’-Diacetic Acid (DACDA) as an Ionophore Susanto Imam Rahayu; Buchari Buchari; Indra Noviandri; Suyanta Suyanta
Jurnal Matematika & Sains Vol 11, No 1 (2006)
Publisher : Institut Teknologi Bandung

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Abstract

A lanthanum(III) ion selective electrode based on ionophore 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N-diacetic acid was studied. The electrode was prepared with an inner solution system in a membrane composition that contained an active ionophore 1,10-diaza-4,7-13,16-tetraoxacycloocta decana-N,N-diacetic acid (DACDA), an anionic side potassium tetrakis (4-chlorophenyl) borate (KTCPB), a plasticizer o-nitro phenyl octyl ether (NPOE) and a polyvinyl chloride (PVC) matrix support. A good response was obtained with a slope of 19.53 ± 1.62 mV/decade and the electrode gave responses with a detection limit of 3.92x10-6 M. The measurement range was wide (10-5-10-1 M) and the responses time was about 27 seconds. The electrode could measure lanthanum ion with a few interfering alkali, earth alkali and transition elements.
The Probability of Flare Occurrences Based on Sunspot Group and Magnetic Configurations Dhani Herdiwijaya; Sherly Imelda
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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We study the probability of flare occurrences observed in Hα and X-ray based on the classification and evolution of sunspot group and the magnetic structure within period 1994 to 2001. We found that there was a strong correlation between flare occurrences with the morphology and configuration of sunspot group and the magnetic structure. We also found that simple sunspot groups move more slowly before flare event, whereas complex groups move faster. On the other hand we did not find correlation between maximum area of sunspot group and the intensity of solar flare.
Pengaruh Pemberian Elisitor Homogenat Jamur Pythium aphanidermatum (Edson) Fitzp. terhadap Kandungan Ajmalisin dalam Kultur Akar Catharantus roseus (L) G. Don Mukarlina Mukarlina; Rizkita Rachmi Esyanti; Arbayah Hamonangan Siregar
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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An experiment to study the effect of elicitor from Pythium aphanidermatum (Edson) Fitzp. on ajmalicine content of Catharanthus roseus (L) G. Don. root culture has been conducted. The C. roseus root culture in Zenk medium (1977) with the the addition of 10-7 M of napthalene acetic acid (NAA) and 10-7 M of benzylaminopurine (BAP) as growth factors was elicited with autoclaved P. aphanidermatum homogenate at concentrations of 0.05, 0.5, 1.0 and 50 mg DW/mL, then harvested at 18, 24, 36, 48, and 72 h after elicitation. The ajmalicine content was analyzed qualitatively and quantitatively by HPLC (High Pressure Liquid Chromatography) connected to chromatopack CR-7A plus. The result showed that ajmalicine content was influenced significantly by the concentration of elicitor and harvesting time. The highest ajmalicine content on the roots i.e. 165.6 ± 1.1 μg/g DW with the increment percentage of 181,6% was obtained by addition of 5.0 mg DW/mL of elicitor for 24 h, while on the media, the highest ajmalicine content i.e. 291.5 ± 0.9 mg DW/mL with the increment percentage of 306,5% was obtained by addition of 5.0 mg DW/mL elicitor for 36 hours. These results indicated that elicitation might be responsible for the higher ajmalicine content in the media compared to its accumulation in the root.
L2 Discretization of the Coulomb Three-body Problem in A Non-orthogonal Laguerre-function Basis Agus Kartono
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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In this paper a general analysis of the three-body Coulomb potential polynomials was presented. The three-body Coulomb wave functions expansion in a non-orthogonal Laguerre-type base function is shown to give two modified Pollaczek polynomials. The frozen-core model is used to examine the three-body Coulomb Hamiltonian. The resulting three-term recurrence relation is a special case of the Pollaczek polynomials which is a set of orthogonal polynomials having a nonempty continuous spectrum in addition to an infinite discrete spectrum. The completeness of the three-body Coulomb wave functions is further studied for different Laguerre basis size.
N-Type Conductivity in Wurtzite Mn-Doped GaN thin Films Grown by Plasma Assisted MOCVD Budi Mulyanti; Agus Subagio; Edi Supriyanto; Heri Sutanto; Fitri Suryani Arsyad; Pepen Arifin; Maman Budiman; Mohamad Barmawi
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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Ferromagnetic semiconductor GaN:Mn thin films were successfully grown by plasma-assisted metalorganic chemical vapor deposition (PA-MOCVD) method on c-plane sapphire substrate. The films were grown at various Mn source flux in the range of 5 - 40 sccm and growth temperature which was lower than that of MOCVD themal, i.e. in the range of 625-700 °C. Cyclopentadienyl manganese tricarbonyl (CpMnT) was used as a source of Mn. X-ray diffraction patterns confirmed that GaN:Mn films are wurtzite and do not show second phase for film with Mn concentration up to 6.4% at 650 °C of growth temperature. Hall effect measurements show n-type characteristics. The carrier (electron) density tends to decreases and Hall mobility tends to with the increase of Mn concentration is increased. Hysteresis curves observed from VSM measurements indicated that all of the samples are ferromagnetic at room temperature.
Optimization of Deposition Parameters for high Quality a-SiGe:H Thin Films Mursal Mursal; Ida Usman; Toto Winata; Sukirno Sukirno; Mohamad Barmawi
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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The effect of substrate temperature and rf power on the characteristics of a-SiGe:H alloys thin films has been investigated. The a-SiGe:H films made from a mixture of 10% silane (SiH4) and 10% germane (GeH4) gas diluted in hydrogen (H2) were grown on corning glass 7059 by using Plasma Enhanced Chemical Vapor Deposition (PECVD) method. The results showed that the deposition rate of a-SiGe:H films increased with the increasing of substrate temperature and rf power. The optical band gap (Eopt) of the films was improved by increasing of the rf power. The dependency of Eopt on the rf power is attributed to the change in Ge content in the films. The photosensitivity (σph/σd) of the films deposited at 200 °C and 175 °C slightly increased with increasing of rf power from 30-50 Watt. For the films deposited at 225 °C, the photosensitivity increased with increasing of rf power from 30-40 Watt, and relatively constant at rf power of 40-60 Watt.
Database and Animation Package of Stellar Evolution Study Mahaseana Putra; Muhamad Irfan Hakim; Aprilia Wardana; Winardi Sutantyo
Jurnal Matematika & Sains Vol 11, No 3 (2006)
Publisher : Institut Teknologi Bandung

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The study of stellar evolution is an active major branch in astrophysics. Results from stellar evolution studies are indispensable for studies in some other areas such as chemical evolution of star clusters and galaxies. Recently theoretical/computational studies of stellar evolution often involve large populations of stars (~106) which need databases of evolution tracks with various realistic parameters (mass, chemical composition, etc). In this paper, an attempt in building such a database and construction of animations of the evolution of stellar internal structures and isochrones which is useful in teaching stellar evolution were described.
Persistensi dan Variabilitas Hidrometeorologi Daerah Aliran Sungai Citarum Ruminta Ruminta; Bayong Tjasyono Hanggoro K.; Indratmo Soekarno
Jurnal Matematika & Sains Vol 11, No 3 (2006)
Publisher : Institut Teknologi Bandung

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The persistences and variabilities of the hydrometeorology had been studied in the Upper Citarum River Basin, West Java, based on monthly observations data of the rainfall, evapotranspiration, humidity, and runoff from January 1968 to December 2000 and monthly global phenomena data from National Centers for Environmental Prediction (NCEP) and National Centers for Atmospheric Research (NCAR) reanalyses. The results showed that rainfall, evapotranspiration, and humidity have two firm persistences i.e. wet and dry periods, while the runoff has no firm persistence. The stability of rainfall and humidity were less than evapotranspiration and runoff; the stability patterns of rainfall tend to increase, whereas, the evapotranspiration tend to decrease; the stability patterns of the humidity and runoff have no firm trends; the rainfall and runoff have very high variability i.e., 73% and 62%, respectively. The result indicated that the processes of the rainfall and runoff were very chaotic, while evapotranspiration and humidity have low variability i.e., 19% and 3%, respectively. These data indicated that the evapotranspiration and humidity have low pattern, variability patterns of the all hydrometeorological components had increasing trends, the hydrometeorological components were influenced by global phenomena as a consequence of the significant correlations between hydrometeorological components and some global phenomenas, especially Central Indian Precipitation (CIP), Global Temperature (GT), Dipole Mode Index (DMI), Pacific Warm Pool (PWP), and Precipitable Water (PW).

Page 11 of 34 | Total Record : 339

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