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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 339 Documents
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In Situ Measurement of the Growth Rate of the (111) Face of Borax Single Crystal Suharso Suharso
Jurnal Matematika & Sains Vol 10, No 3 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

The quality of borax crystals is determined by grade and specifically shaped crystals of high purity. One of fundamental studies of this quality is an investigation of the growth rate of each face of borax single crystals. This paper studies the growth rates of borax single crystals along the (111) direction at various relative supersaturations using in situ optical microscopy technique to elucidate mechanism of growth and crystal growth rate equation. The result shows that the growth mechanisms of the (111) face of borax crystal at temperature of 20°C are spiral growth mechanism below relative supersaturation of 0.49 and a birth and spread mechanism above relative supersaturation of 0.49.
Anisotropi Magnetik Film Tipis TiO2:Co yang Ditumbuhkan dengan Teknik MOCVD Horasdia Saragih; Pepen Arifin; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

TiO2:Co thin films have been successfully deposited by using MOCVD technique. The titanium (IV) isopropoxide [Ti(OCH(CH3)2)4] 99,99%, tris (2,2,6,6-tetramethyl-3, 5-heptanedionato) cobalt (III) 99%, and oxygen gas (O2) were used as Ti, Co, and O precursors, respectively. Crystal structure, morphology and magnetic properties of thin films were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), and vibrating sample magnetometer (VSM), respectively. The magnetic anisotropy (K) of thin films was very strong depended on the growth temperatures. The thin film grown at temperature of 400°C has anatase-213 structure and K value of 40000 Oe.emu/cm3. At the growth temperature of 450°C, the thin films were has still anatase-213 and K value of 95000 Oe.emu/cm3. At growth temperature of 500°C, the thin films have K value of 72000 Oe.emu/cm3. The crystal structure of films was changed with an additional plane of anatase-301. The thin film grown at temperature of 550°C has K value of 103600 Oe.emu/cm3. The structure of thin film was polycrystalline, mixed by anatase-213, rutile-220 and TiCoO3 (310) phase. All of films have thickness of about 0,7-0,9 µm.
Model Inklusi Silinder dalam Jaringan Homogen untuk Elastografi Biomedik Idam Arif; Astalini Astalini
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

A cylindrical inclusion model in a tissue matrix is proposed for biomedical elastography. Solutions of elasticity equation are applied to observe the effects of the inclusion on the distribution of a uniform stress given to the matrix. The inclusion and the matrix are assumed to be isotropic, homogen, and linear. The obtained analytical solutions are illustrated in the form of graphics for breast tumors and cysts. It is shown that the effects are located in the region less than 3R, with R being the inclusion radius. If the inclusion is stiffer than the matrix (µb>µt), then the displacement in z direction is negative and is positive in y direction. It means that the strain and stress components in z direction (ezz,szz) are negative and (eyy,syy) are positive in y direction. If the inclusion is softer than the matrix (µb>µt) then the displacement in z and y directions is negative. Therefore the strain and stress components in z direction and in y direction both are also negative.
Pengaruh Daya RF terhadap Kandungan Ge dan Sifat Opto-Elektronik Lapisan Tipis a-SiGe:H Mursal Mursal; Amiruddin Supu; Ida Usman; Toto Winata; Sukirno Sukirno
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

The effect of rf power on Ge content (CGe) and opto-electronic properties of a-SiGe:H thin films deposited by PECVD method had been investigated. a-SiGe:H thin films were grown on corning glass 7059 substrate from a gas mixture of SiH4 and GeH4 10% diluted in H2, respectively. The substrate temperature was kept at 275oC and the rf power was varied from 50 - 120 Watt. The results showed that the CGe of a-SiGe:H thin films decreases with increasing in rf power, and therefore the optical bandgap (Eopt) increases. We found that the optimum rf power was 90 Watt, which corresponds to the highest photo-sensitivity of 1.43 x 104.
Botulinus Toxin (“Botox”) Edward J. Wood; Amanda North
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

The toxin produced by the bacterium Clostridium botulinum is one of the most lethal toxins known. The structure of the type A toxin has been solved by x-ray crystallography and this reveals how the toxin acts. The 150kDa molecule is in three parts, a receptor-binding domain that enables it to bind to nerve cells, a translocation domain that enables the toxin to enter the cells, and a protease domain that specifically digests proteins concerned with the delivery of the neurotransmitter acetylcholine at the neuromuscular junction leading to paralysis of the muscles required for breathing. Despite its highly lethal nature the type A toxin, as Botox®, is used medically in tiny doses to treat a number of clinical conditions, and more recently cosmetically, to remove wrinkles and frown lines.
Sintesis Kopoliester dari ε- Kaprolakton dan 2,2-dimetil-1,3-Propandiol: Prepolimer Alternatif untuk Sintesis Poliester Berat Molekul Tinggi M. Hasan; S.I. Rahayu; I Made Arcana; Cynthia Linaya Radiman
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

Copolyesters from ε- caprolactone and 2,2-dimethyl-1,3-propanediol have been synthesized by using distannoxane as catalyst. The influence of monomer compositions on viscosity, melting point and structure of polyesters was studied. The results showed that the increase of ε- caprolactone content in copolymer increased the melting point and viscosity of polyester. This was supported by the decrease of hydroxyl number of polyester when the ε- caprolactone monomers in the copolymers increased.
Tiga Senyawa Oligostilbenoid dari Kulit Batang Dipterocarpus retusus Blume (Dipterocarpaceae) Muhtadi Muhtadi; Euis Holisotan Hakim; Yana Maolana Syah; Lia Dewi Juliawaty; Sjamsul Arifin Achmad; Ikram M. Said; Jalifah Latip
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

Three oligostilbenoids, (-)-ε-viniferin, (-)-α-viniferin and (-)-vaticanol A, together with two derivative coumarin compounds, scopoletin and (-)-bergenin, were isolated from acetone extracts of the tree bark of Dipterocarpus retusus Blume. The chemical structure of the isolates were established based on spectroscopic data, UV, IR, 1H-NMR, 13C-NMR, and by comparison with the related compounds. (-)-ε-Viniferin, (-)-α-viniferin and (-)-vaticanol A showed cytotoxic activity against murine leukaemia P-388 cells with their IC50 values were 7,8; 17,5 and 27,0 µg/mL, respectively.
Pengaruh Temperatur Deposisi Lapisan Penyangga Aluminium Nitrida terhadap Struktur Kristal dan Morfologi Film Tipis GaN dengan Metoda DC Unbalanced Magnetron Sputtering Dadi Rusdiana
Jurnal Matematika & Sains Vol 11, No 1 (2006)
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Abstract

Gallium nitride thin films were grown on (0001) sapphire substrates by DC unbalanced magnetron sputtering using of aluminum nitride buffer layer. The properties of GaN thin films were improved by optimization of the growth temperature of buffer layers between 450 °C to 700 °C. Results showed that GaN film properties such as crystal structures and morphological properties were improved. XRD characterization shows that there was most probability to create a better of crystal structure with orientations of (1011) and (1120) with FWHM 0.3° and 0.6° respectively if the growth temperature of buffer layer was 450 °C.
S-Brane Solutions with Accelerating Cosmology in M-theory Freddy Permana Zen; Arianto Arianto; Bobby Eka Gunara; Selly Feranie
Jurnal Matematika & Sains Vol 11, No 1 (2006)
Publisher : Institut Teknologi Bandung

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Abstract

We study the expansion and accelerated expansion of universe from S-branes of the M-theory. The dynamics of expansion is described by the scale factor of S-brane solutions and equation of state from the S-bran dark energy models. We provide analytic expressions to calculate the equation of state of these models as a function of time. Moreover, we also study cosmological expansion with the intersection solutions, which may have an interesting characteristic, namely, they never obtain the accelerated expansion. The critical expansion is given by the limit β→0.
Karakteristik Struktur dan Listrik Film Tipis GaN yang Ditumbuhkan di atas Substrat Si(111) dengan Metode Plasma Assisted-Metalorganic Chemical Vapor Deposition (PA-MOCVD) Heri Sutanto; Agus Subagio; Edi Supriyanto; Pepen Arifin; Sukirno Sukirno; Maman Budiman; Mohamad Barmawi
Jurnal Matematika & Sains Vol 11, No 1 (2006)
Publisher : Institut Teknologi Bandung

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Abstract

Gallium nitride (GaN) thin films have been grown on Si(111) substrate by PA-MOCVD method, with trimethylgallium (TMGa) and radical nitrogen resulted by plasma of nitrogen gas as a source of Ga and N respectively. The growth was performed at 675 °C; 0.4 torr; 90 sccm and 0.08-0.12 sccm of substrate temperature, reactor pressure, gas flow of nitrogen and TMGa, respectively. The grown polycrystalline GaN thin films have hexagonal structure and n-type semiconductor. The growth rate of the grown thin films increased with increasing gas flow of TMGa. The Hall mobility value of films is still low due to the presence of O and C impurities. The highest value of mobility was found to be 64.88 cm2/V.s with 5.47 x 1018 cm-3 of carrier concentration.

Page 10 of 34 | Total Record : 339

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