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INDONESIA
Jurnal Matematika & Sains
Published by Institut Teknologi Bandung
ISSN : -     EISSN : -     DOI : -
Core Subject : Education,
Mathematics
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Articles 5 Documents
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Search results for , issue " Vol 12, No 3 (2007)" : 5 Documents clear
Recalculating the Orbit of α-Centauri AB Suryadi Siregar; Hanindyo Kuncarayakti
Jurnal Matematika & Sains Vol 12, No 3 (2007)
Publisher : Institut Teknologi Bandung

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Abstract

The two main components of the closest star system, α Centauri AB (RA 14h39m, Dec -60o50, J2000.0) is indubitablyone of the most studied visual double stars. This paper presents the results of our recalculation of orbital and physicalparameters of the system using Thiele-van den Bos method, based on observational data from year 1900 to 2002.Despite some significant discrepancies, in general our results confirmed previous results of orbital parameterdeterminations using different method.
Studi Pengaruh Rasio Masukan Sumber V/III Terhadap Distribusi Sb dan Karakteristik Kelistrikan Lapisan Tipis GaAs1-x Sbx yang Ditumbuhkan dengan Teknik MOCVD [On the Study of the Effect of Source Input V/III to the Distribution of Sb and Electricity.....] Andi Suhandi; Pepen Arifin; Maman Budiman; Muhamad Barmawi
Jurnal Matematika & Sains Vol 12, No 3 (2007)
Publisher : Institut Teknologi Bandung

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Abstract

The study of the dependence of the Sb distribution in GaAs1-xSbx films and the electric properties of the GaAs1-xSbx filmsgrown by MOCVD technique using TMGa, TDMAAs, and TDMASb to the V/III source input ratio has been done. The Sbsolid composition in GaAs1-xSbx film was determined by using Vegards law from the shift of the peak intensity of X-raydiffraction pattern. Electric properties of the GaAs1-xSbx films were investigated through room temperature Hall effectmeasurement. The results suggest that the concentration of Sb incorporation into the GaAs1-xSbx films is stronglyaffected by V/III source input ratio. For V/III source input ratio of unity, the Sb distribution coefficient, which is theratio of the Sb composition in GaAs1-xSbx solid to the Sb vapor input mole fraction, is nearly unity. The Sb distributioncoefficient decreases with increasing of V/III source input ratio, for V/III input ratio langer than 1. The range of carriermobility are between 200 – 430 cm2/V.s, depending on the V/III input ratio, and the Sb composition. The highest carriermobility occurred at V/III input ratio of approximately one.
Ekstraksi dan Pemisahan Penisilin G dari Fenilasetat dengan Teknik Membran Cair Emulsi Imam Santoso; Buchari Buchari; Muhammad Bachri Amran; Aminudin Sulaeman
Jurnal Matematika & Sains Vol 12, No 3 (2007)
Publisher : Institut Teknologi Bandung

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Abstract

The separation and purification of penicillin G from phenyl acetic acid (PAA) is very difficult to be carried out becausethe two compounds are weak acids and the two compounds can change from one to another by influence of pH. The aimof this research is to establish the optimal conditions for the extraction and separation of penicillin G from phenylaceticacid using the emulsion liquid membrane technique. The optimal conditions were ratio of internal phase volume tomembrane phase volume of 1:1; time of stiring for emulsion preparation of 1 minute; emulsion contact rate of 300 rpm;emulsion contact time of 15 minutes; rate of stirring of emulsion of 2000 rpm; rest time of emulsion of 13 minutes;concentration of penicillin G as external phase 375 ppm; and concentration of surfactant 5% (v/v). At these conditionspenicillin G can be extracted and separated from phenylacetic acid with a separation factor of 19.3 and a contact timeof 15 minutes. Thus the technique of emulsion liquid membrane may be used as a reasonably effective method toseparate penicillin G from phenylacetic acid.
Intramolecular Forces Density in Mesophilic and Thermophilic Proteins: Amino Acid Clusters Based Study Rukman Hertadi; Minoru Kanehisa
Jurnal Matematika & Sains Vol 12, No 3 (2007)
Publisher : Institut Teknologi Bandung

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Abstract

Thermostability of (hyper)thermophilic enzymes has been taken as an advantage in industry to enhance biochemicalreactions at elevated temperature. Factors responsible for the thermostability in this class of proteins, however, stillremain unclear despite the many works that have been done to elucidate such factors by performing variouscomparative studies to homologous pairs of (hyper)thermophilic and mesophilic proteins. In the current work, weelucidated the factors by comparing intramolecular forces density in tertiary structure of mesophilic and(hyper)thermophilic proteins in terms of the content of various types of amino acid clusters. A graph spectral methodwas employed to probe the charged, hydrophobic and aromatic clusters in each tertiary structure of all classes ofthermophilic proteins used in our study. Our results revealed that mesophilic and (hyper)thermophilic proteins containsimilar level of all types of amino clusters, thereby stabilized with similar level of high-density intramolecular forces,but the former contain a higher number of non-cluster residues and less stabilized by electrostatic interactions, therebymore sensitive to heat.
Oligomer Resveratrol dari Kulit Batang Shorea assamica Dyer (Dipterocarpaceae) dan Sitotoksitasnya Sahidin Sahidin; Euis Holisotan Hakim; Yana Maolana Syah; Lia Dewi Juliawaty; Sjamsul Arifin Achmad; Nordin Hj Lajis
Jurnal Matematika & Sains Vol 12, No 3 (2007)
Publisher : Institut Teknologi Bandung

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Abstract

Four resveratrol oligomers which consist of two resveratrol trimers, i.e., vaticanol A (1) and α-viniferin (2), and two resveratrol tetramers, i.e., vaticanol B (3), and isohopeafenol (4) have been isolated from acetone extract of the stem bark of Shorea assamica Dyer. The elucidations on the structure of these four compounds were based on the spectroscopic data, including UV, IR, 1-D and 2D NMR spectra, and comparison with related data reported previously. Cytotoxicity of the isolated compounds against murine leukemia P-388 cells exhibited that vaticanol A (1), α-viniferin (2), vaticanol B (3) dan isohopeaphenol (4) had IC50 of 27.0, 17.5, 46.4, and 36.0 ppm, respectively. The results showed that cytotoxicity of resveratrol trimers were relatively higher than resveratrol tetramers.

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