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Journal of Mathematical and Fundamental Sciences
Published by Institut Teknologi Bandung
ISSN : 23375760     EISSN : 23385510     DOI : https://doi.org/10.5614/j.math.fund.sci.
Core Subject : Science, Education,
Astronomy Chemistry Earth & Planetary Sciences Mathematics Physics
Journal of Mathematical and Fundamental Sciences welcomes full research articles in the area of Mathematics and Natural Sciences from the following subject areas: Astronomy, Chemistry, Earth Sciences (Geodesy, Geology, Geophysics, Oceanography, Meteorology), Life Sciences (Agriculture, Biochemistry, Biology, Health, Medical, Pharmacy), Mathematics, Physics, and Statistics.
Arjuna Subject : Matematika - Matematika (Lain-Lain)
Articles 689 Documents
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Pengaruh Jenis Poliol terhadap Pembentukan Poliuretan dari Monomer PEG400 dan MDI Eli Rohaeti; N. M. Surdia; Cynthia L. Radiman; E. Ratnaningsih
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 2 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.2.2

Abstract

The properties of polyurethane depend largely on building blocks, especially the kind of polyol. Not only pure synthetic compounds but also various natural substances such as saccharides (glucose, fructose, maltose, sucrose) and amylose can be used as possible resources of polyol in polyurethane synthesis. Those natural substances are natural polymeric materials having appropriate reactivity thank to its functional groups such as hydroxyl groups. Natural polymers having more than two hydroxyl groups per molecule can be used as polyols for polyurethane synthesis. In this study, the effect of addition of saccharide (glucose, maltose) and amylose in the synthesis polyethylene glycol 400 (PEG400) and methylene-4,4'-diphenyldiisocyanate (MDI) based polyurethane was studied by measuring the hydrogen bonding index (HBI) and the thermal properties. Characterization of functional groups in resultant polyurethane was analyzed by FTIR spectrophotometry, the thermal properties were conducted with Differential Thermal Analysis (DTA), Differential Scanning Calorimetry (DSC), and Thermal Gravimetric Analysis (TGA). The addition of saccharide (glucose, maltose) and amylose on the synthesis polyurethane from polyethylene glycol 400 (PEG400) and methylene-4,4'-diphenyldiisocyanate (MDI) can increase the hydrogen bonding index and the glass transition temperature of polyurethane. In all case the increase of glucose unit in polyol can increase the hydrogen bonding index, the glass transition temperature, and the thermal stability of polyurethane.
Domain Motion in 3-isopropylmalate dehydrogenase: A Strategy to Enhance its Thermal Stability Zeily Nurachman; Tairo Oshima; Nobuo Tanaka
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 2 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.2.6

Abstract

In order to elucidate the thermal properties of Thermus thermophilus 3-isopropylmalate dehydrogenase, mutant structures with mutations at the C-terminus were compared with each other. The structural movement can be anticipated from the structural changes among mutants in regions of a minor groove and pillar. Our previous studies revealed that the open-close movement of the active site groove antagonizes to that of the minor groove (like a paperclip) and the thermostability of the enzyme increases when the active site groove is closed. In the present study, it is shown that the motion of the enzyme mainly occurs in the first domain and strand D in the pillar structure is a hinge-bending region of the movement. The motion of the first domain to expand the minor groove may close the active site groove suggesting a mechanism for the enhanced thermal stability of 3-isopropylmalate dehydrogenase.
The Non Linear Finite Element Model for Characterization of Brick Masonry Infill Wall under Cyclic Lateral Forces B. Budiono; Herwani Herwani
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 2 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.2.4

Abstract

Brick masonries as the infill walls between columns, for some degree of horizontal loading, are capable of resisting the horizontal load as shear walls. The different behavior of the structure due to the existence of the brick masonries in this case will change the stiffness as well as the strength of the structure. Ignoring this contribution of the brick masonries develops a misleading concept and design for the structure. In this study, a mathematical model representing the relationship between uniaxial stress vs. strain and the failure envelope of the infill brick wall masonry is developed. The implementation of the model is expected to be capable for analyzing the behavior of the structures subjected to external load in particular under cyclic loading. The model assumes that the contribution of the infill walls are taken into account for the analysis and the brick material used is considered as a compression dominated material. Analysis was carried out using non-linear discrete finite element method. Eight nodal isoparametric elements are developed representing concrete and brick masonry elements. Steel reinforcement and linkage elements are modeled as three nodal plane truss element. The variables studied in the analysis are degree of energy dissipation and stiffness degradation. The result showed that the model gives satisfactory results. However, some improvement needs to be considered in the linkage element model.
Kultur Campuran dan Faktor Lingkungan Mikroorganisme yang Berperan dalam Fermentasi “Tea-Cider” Pingkan Aditiwati; Kusnadi Kusnadi
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 2 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.2.5

Abstract

Tea is agricultural product containing beneficial substances, especially used for human health. The study of "Tea-cider" fermentation has been conducted using batch culture method. The purposes of the study were to observe mixed microbial culture which were actively involved in the process of "Tea-cider" fermentation, to determine the optimum fermentation conditions, as well as to evaluate the inhibition effect of the product against pathogenic bacteria. The study was carried out in two steps. Firstly, the isolation of microorganisms from "Tea-cider"; secondly producing "Tea-cider" using mixed microbial culture isolated from "Tea-cider" and "Tea-cider" itself as inoculum. Type and concentration of inoculum were optimized for the fermentation process. Mixed of the pure culture of isolated microorganisms with variation of initial cell at ratio B : K1 : K2 = 1 : 1 : 1, 3 : 1 : 1 and 5 : 1 : 1 while the variation of inoculum were 5%, 10%, and 15% (v/v). Optimization in temperature, pH and sugar concentration at the variation of temperature 250C, 280C, 300C, and 350C, pH of 4, 5, and 6, and sugar concentration 5%, 10%, and 15% (w/v) respectively. The pH, acid concentration, reducing sugar concentration and alcohol concentration were analized at 48 hours interval during 14 days fermentation. The product was tested for antimicrobial effect using agar diffusion method and for organoleptic. The result showed that mixed microbial culture which were actively involved in "Tea-cider" fermentation were yeast Schizosaccharomyces pombe (K1) dan Brettanomyces sp (K2), and a species af aceticacid Acetobacter xylinum (B). The optimum condition of "Tea-cider" fermentation were as follows, the ratio of B : K1 : K2 optimum mixed culture inoculum at 5 : 1 : 1 and 10% (v/v) for the inoculum. The incubation temperature was 300C, the medium initial pH was 5 and the intial sugar concentration was 10% (w/v). The "Tea-cider" product was able to inhibit the growth of some pathogenic bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli and had a good preferred taste.
Variasi Nilai Gradien Hidrolik dan Pengaruhnya terhadap Perubahan Nilai Tahanan Jenis pada Sistem Akifer Bersudut Berdasarkan Pendekatan Model Fisik Budiono Budiono; Deny Juanda Puradimaja; Sulistijo Sulistijo
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 2 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.2.7

Abstract

The core of this research is simulation on a physical model of inclined confined aquifer in laboratory scale. The model dimensions is 79.50 cm long, 78.00 cm wide, and 10.00 cm tall. The aquifer is simulated as single confined aquifer with thickness of 8 cm. The aquifer material is composed of coarse sand with good gradation and has uniformity coefficient of 7.105. The measurements consist of elevation head (z), pressure head (hp), total head (h), and resistivity with Schlumberger configuration. The confined aquifer layer is set up to be horizontal. Then, in order to get the hydraulic gradient and dip layer variations, the position of the model box is inclined with varied degree of: 00, 100, 200, and 270. To get the most representative result, the resistivity is measured with line spread parallel to strike and perpendicular to strike.The analysis shows that the increase of the hydraulic gradient (i) have the tendency to cause the decrease of true resistivity values (ρ). Based on the line spread direction and R2 values, there are 2 representatives equations as follows: 1). With line spread parallel to strike:4,88ln()64,60ρ=−+i;R2=0,95. 2). With line spread perpendicular to strike without correction on AB/2 and K value:ρ=;R3,80ln()58,20−+i2=0,99.
Pengujian Prototip Suspensi Aktif Tegar (Robust) Model Seperempat Kendaraan Nyoman Bangsing
Journal of Mathematical and Fundamental Sciences Vol. 36 No. 1 (2004)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2004.36.1.6

Abstract

In this paper the result of the performance test of a robust-active suspension system will be presented. The performance of the developed suspension system was evaluated under a sinusoidal road disturbance with amplitude of 3 mm (peak to peak), and within the frequency test range of 1 "“ 9 Hz. The experimental results show that in the frequency test range of 1 "“ 4 Hz, the sprung mass acceleration of the active suspension is smaller than that of the passive suspension. However, the sprung mass acceleration of the active suspension is higher than that of the passive one, in the frequency test range of 5 "“ 9 Hz. Moreover, the unsprung mass acceleration of the active suspension is smaller than its passive counterpart in all of the frequency test range 1 "“ 9 Hz.
Pengolahan Fasa untuk Mendapatkan Model Tinggi Permukaan Dijital (DEM) pada Radar Apertur Sintetik Interferometri (INSAR) Data Satelit Ishak Hanafiah Ismullah
Journal of Mathematical and Fundamental Sciences Vol. 36 No. 1 (2004)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2004.36.1.2

Abstract

Comparing to optical sensors, radar technology has only just begun. Mapping by optical sensors, especially with Photogrammetric methode shows a very good result, but the main constraint is cloud cover conditions, and this was the weakness point of the Photogrammetric techniques. Indonesia is a tropical country which has dominant cloud coverage, and some of the area has cloud cover almost all year long. Radar imaging has some advantages e.q. sun independence, cloud penetration etc. Active systems in ERS1, ERS2, RADARSAT, JERS, and ENVISAT make possible to do interferometric processing. This paper try to explain how to process phase information from radar satellite data especially from ERS1 and ERS2. The result has been compared with the Digital Photogrammetric technigue, for Papandayan and Cikurai vulcano, West Java.
Pengaruh Dua Macam Perlakuan Mikroorganisme terhadap Kemudahan Degradasi Poliuretan Hasil Sintesis dari Monomer Polietilen Glikol Berat Molekul 400 dengan Metilen-4,4’- difenildiisosianat E. Rohaeti; N. M. Surdia; C. L. Radiman; E. Ratnaningsih
Journal of Mathematical and Fundamental Sciences Vol. 36 No. 1 (2004)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2004.36.1.1

Abstract

Degradation of polyurethane sheets using two types of microorganism treatment has been carried out. In this research, the polyurethane sheets were prepared by polyethylene glycol with a molecular weight of 400 and methylene-4,4'-diphenyldiisocyanate at room temperature, followed by heat-pressed at temperature of 180oC. Characterization of polyurethane sheets was based on functional groups using Fourier Transform Infra Red spectrophotometry and thermal properties using Differential Thermal Analysis, and also for physical properties using X-Ray Diffraction. Degradation treatment was carried out by exposing polyurethane to activated sludge and compared to Pseudomonas aeruginosa in a Luria Bertani liquid media at 37oC. The variation of incubation time was 5, 10, 15, 20, 25, and 30 days, respectively with changes of media every 5 days. After degradation, weight loss of polyurethane sheets was determined. The result showed that polyurethane was biodegradable, although at different degradation rate. Weight loss of polyurethanes by activated sludge was higher than by Pseudomonas aeruginosa. Thus, activated sludge was more effective than Pseudomonas aeruginosa in degradating polyurethane. Identification with X-Ray Diffraction showed that degradation decreased the degree of crystallinity of the polyurethane material. Fourier Transform Infra Red spectra after degradation showed that the specific peak for the urethane group disappeared. Variation of the incubation time showed that the polyurethane product had the highest weight loss during the first five days.
Pengaruh Konsentrasi Oksidator pada Proses Hidroksilasi Minyak Jarak (Castor Oil) Dengan atau Tanpa Proteksi Gugus Hidroksi Marlina Marlina; N. M. Surdia; C. L. Radiman; S. Achmad
Journal of Mathematical and Fundamental Sciences Vol. 36 No. 1 (2004)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2004.36.1.3

Abstract

Oil is derived from the bean of castor plant ricinus communis l., belonging to euphorbiaceae family. Oil rendement per gram of castor bean is 45 "“ 48 % with hight pure product and better than standard resulted by The Association of Official Analytical Chemistry (AOAC). The main components in castor oil are oleic, palmitic and resinoleic acid. Protection process by acetylation occurs well on hydroxyl group of castor oil, indicated by increasing of iodine number and decreasing of hydroxyl number. Oxidation process is more efective on protected oil than non protected oil. The excess of oxidator concentration changed the product to be aldehide and carboxylic acid. Optimum condition was reached when oxidator concentration was 15 %, with hydroxyl value of 1280.438 mg/g and iodine number of 33.093 mg/g.
Penurunan Zat Organik dan Kekeruhan Menggunakan Teknologi Membran Ultrafiltrasi dengan Sistem Aliran Dead-End (Studi Kasus : Waduk Saguling, Padalarang) Suprihanto Notodarmojo; Anne Deniva
Journal of Mathematical and Fundamental Sciences Vol. 36 No. 1 (2004)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2004.36.1.5

Abstract

A laboratory scale experiment to study the aplicability of ultrafiltration membrane technology to treat the water of Saguling Reservoir has been done. The main parameters in this study are flux, organic content, and turbidity. The membranes used are cellulose accetate based membrane, composed of 11, 13, 15 percent cellulose accetate respectively. Chemical analysis of Saguling Reservoir water shows that, color, organic content, and turbidity are the parameters exceeding the standard. In this study, treated water by using Poly Alummunium Chloride (PAC) as feeding solution was also been used. The results shows that CA-15, membrane has 15 % content of cellulose accetate, performed best. The permeability of the membrane was 5-12 l/m2.hr.bar, and rejects up to 90 % of organic content, 90-100% rejection of Total Suspended Solid and 90% turbidity.

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