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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 13, No 2 (2008)" : 5 Documents clear
Aktifitas Antioksidan dan Inhibitor Tirosinase Beberapa Stilbenoid dari Tumbuhan Moraceae dan Dipterocarpaceae yang Potensial untuk Bahan Kosmetik Didin Mujahidin; Euis Holisotan Hakim; Yana Maolana Syah; Lia Dewi Juliawati
Jurnal Matematika & Sains Vol 13, No 2 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

In a drug discovery program to combat various diseases, many natural chemicals originating from Indonesian tropicalplants including Moraceae and Dipterocarpaceae have been investigated in our laboratory. These family of plants areknown as rich sources of stilbenoid type of compounds which have been shown to have various bioactivities, that arepotentially important in cosmetic bioindustry. In the course of our search for bioactive natural products from plants, wewere interested in the stilbenoid constituents of these plants. Thus, as part of this program, several stilbene derivativeswere successfully isolated from extracts of Morus macroura, a Moraceous plant locally named andalas, includingoxyresveratrol (1), lunularin (2) and new resveratrol dimers, namely andalasin A (3) and andalasin B (4). While,biotransformation of oxyresveratrol (1) using cell suspension culture of Solanum mammosum affordedtrans-oxyresveratrol-4-O-β-D-glucopyranoside (5). Similarly, some resveratrol derivatives have been isolated fromDipterocarpaceous plants, such as Shorea assamica, S. seminis, Vatica umbonata, and Dryobalanops oblongifolia.These species gave, among others, resveratrol (6), resveratrol-12-C-β-glucopyranoside (7), the resveratrol dimers(-)-ε-viniferin (8) and the new compound diptoindonesin A (9), in addition to resveratrol trimers (-)-α-viniferin (10), thenew compounds cis-diptoindonesin B (11) and trans-diptoindonesin B (12). Among these compounds oxyresveratrol (1),andalasin B (4), trans-oxyresveratrol-4-O-β-D-glucopyranoside (5), resveratrol (6), cis-diptoindonesin B (11) andtrans-diptoindonesin B (12) exhibited the most potent antioxidant activity [1,1-diphenyl-2-picrylhydrazil (DPPH)radical-scavenging activity]; moreover, andalasin A (3) have been reported to show a very strong tirosinase inhibitoractivity, thus valuable in cosmetic industry.
Effect of Cytokinins and Carbenicillin on In vitro Axillary-Shoot Growth of Albizia [Albizia falcataria (L.) Fosberg] Sri Nanan Widiyanto; Mirah Dila Sari; Rina Ratnasih Irwanto
Jurnal Matematika & Sains Vol 13, No 2 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

Effect of N6-benzylaminopurine (BA), 6-furfurylaminopurine (kinetin) and carbenicillin on axillary-shoot growth ofalbizia [Albizia falcataria (L.) Fosberg] from cotyledonary node-segments were evaluated in vitro. Shoot inductionmedium was composed of Murashige and Skoog (MS) basal medium with or without the addition of BA or kinetin. Thesensitivity to carbenicillin was tested using shoot induction medium with the addition of carbenicillin at 10-50 mg/L.The results showed that the optimal axillary-shoot growth was observed on medium containing 2.2 μM BA and 2.3 μMkinetin, which reached the average of 36.0±2,2 mm shoot-length and 2.9±1,1 nodes/shoot in four weeks. The addition ofcarbenicillin inhibited the axillary-shoot growth, shown by 6.1-11.5 mm of shoot length of and 1.0-11.1 of nodes/shoot.A total of 60 shoots were elongated and rooted in in vitro condition on MS medium without growth regulator. Allplantlets were successfully transferred to a soil-sand medium (1:1) and grew well in the green-house.
Fotokonduktor Al-GaN-Al untuk Aplikasi Detektor Ultraviolet Dadi Rusdiana
Jurnal Matematika & Sains Vol 13, No 2 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

An ultraviolet detector has been fabricated from a GaN thin film with Al-GaN-Al photoconductor structure. The I-Vcharacterization on the photoconductor samples under irradiation condition indicates an increase in the electronconcentration to 4.6 × 1018 cm-3 with photoconductivity of 59.9 Ω-1cm-1, whereas under dark condition thephotoconductivity is 45.7 Ω -1cm-1. There is an increase in the conductivity by about 14.2 Ω-1cm-1 as a result fromirradiation by photons with energy 3.4 eV. The I-V curve also yields a contact resistance of around 0.26 Ωcm3 withbarrier height between aluminum and GaN of 0.44 eV in dark condition, whereas with irradiation the barrier reduces to0.43 eV. The low contact resistance indicates that aluminum contact has an ohmic contact characteristic with type-nGaN semiconductor. The measurements on spectral responses of the photoconductor samples show that the samples arequite sensitive to light with wavelength between 345 nm and 365 nm which is in ultraviolet range. For wavelengthlonger than 365 nm the current response drops significantly. This suggests that the samples have a cutoff wavelength λcof about 365 nm.
Uncertainty Assessment of Alpha-Spectrometry Analysis of 210Po in Marine Sediment Sample from Jakarta Bay Ali Arman Lubis
Jurnal Matematika & Sains Vol 13, No 2 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

The expression of measurement uncertainties in a standardized form is a requirement for result reliability as it imposesimplications to the interpretation of analytical results. In this work, the analytical procedure involves samplepreparation steps for drying, dissolution and further radiochemical separation, self deposition and counting of 210Po ofmarine sediment sample are discussed. An isotopic tracer (209Po) is used to determine the overall chemical yield and toensure traceability to a national standard. The uncertainty assessment of 210Po is discussed using marine sedimentsample from Jakarta Bay with quality assurance based on Standard Reference Material, International Atomic EnergyAgency, No. 300 (SRM IAEA-300) and SRM IAEA-368 for marine sediments. 210Po is measured by a PIPS detectorcoupled to a multichannel spectrometer. The contribution of the sources to the expanded standard uncertainty in theconcentration of 210Po in marine sediment is assessed and the sample activity which contributed 71.10% of total isidentified as the major contribution.
Sintesis dan Karakterisasi Struktur Kristal Ion [Cr3O(OOCC6H5)6(H2O)3]4[α-SiW12O40]⋅10H2O⋅8CH3COCH3 Aldes Lesbani
Jurnal Matematika & Sains Vol 13, No 2 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

The complexation of polyoxometalate K4[α-SiW12O40] and organometallic complex of [Cr3O(OOCC6H5)6(H2O)3](NO3)forms ionic crystal of [Cr3O(OOCC6H5)6(H2O)3]4[α-SiW12O40]⋅10H2O⋅8CH3COCH3 (1a). Single crystal XRD analysisshowed that benzoic groups of organometallic complex were stacked to form eight-membered ring. The π-π interactionmay stabilize the crystal structure of 1a. FT-IR spectrum of ionic crystal showed that characteristic vibration ofpolyoxometalate and organometallic compound existed in the crystal. The amount of water molecules in 1a wasdetermined by using TG-DTA analysis. Ten water molecules were found in the ionic crystal of 1a. The GC analysisshowed that eight acetone molecules existed in the ionic crystal of 1a.

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