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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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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 (Âµb>Âµt), 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 (Âµb>Âµt) 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.

Calcium Release from Cell Walls of Pea Epicotyls Caused by Proton Extrusion during Fusicoccin Action Idam Arif
Jurnal Matematika & Sains Vol 16, No 2 (2011)
Publisher : Institut Teknologi Bandung

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Proton and calcium net fluxes were measured simultaneously during fusicoccin action on peeled Pisum sativum L. epicotyl segments. The measurement employs ion selective microelectrodes to determine the fluxes. The membrane potential of parenchymal cells during the action was also measured. Fusicoccin at 10-3Â mol m-3Â causes immediate proton and calcium effluxes reaching about 60 and 80 nmol m-2Â s-1Â respectively within 40 minutes. It also causes membrane hyperpolarization of about -22 mV. The responses to 10-2Â mol m-3Â fusicoccin are larger. The data fit the Weak-Acid Donnan Manning model for exchange between wall calcium and extruded protons during fusicoccin action on peas. Keywords: Wall calcium, Ion exchange, Proton extrusion, Fusicoccin. Pelepasan Kalsium dari Dinding Sel Epikotil Kacang Polong yang Disebabkan oleh Ekstrusi Proton Selama Aksi Fusicoccin Abstrak Flux netto ion proton dan kalsium diukur secara bersamaan selama aksi fusicoccin pada segmen epikotil Pisum sativum L. yang dikupas epidermisnya. Â Pengukuran tersebut memakai mikroelektroda yang selektif hanya pada suatu ion untuk menentukan besarnya flux ion tersebut. Potensial membran sel parenkim selama aksi fusicocin tersebut juga diukur. Fusicoccin dengan konsentrasi 10-3Â mol m-3Â langsung menyebabkan efflux ion proton dan kalsium yang masing masing mencapai sekitar 60 dan 80 nmol m-2Â s-1Â dalam waktu 40 menit. Fusicoccin dengan konsentrasi yang samaÂ juga menyebabkan hiperpolarisasi membran sel sekitar -22 mV. Fusicoccin dengan konsentrasi yang lebih tinggi, yaitu10-2Â mol m-3, menyebabkan respon yangÂ lebih besar. Data tersebut bersesuaian dengan model Weak-Acid Donnan Manning yang menjelaskan pertukaran antara kalsium yang terkondensasi dalam dinding sel dengan proton yang keluar dari dalam sel selama aksi fusicoccin pada kacang polong. Kata kunci: Kalsium dinding sel, Pertukaran ion, Ekstrusi proton, Fusicoccin.

Respon Berbagai Bentuk, Ukuran dan Bahan Elektroda Pada Pengayaan Elektrolisis Tritium dalam Sampel Air Hidayanto, Eko; Tjahaja, Poppy Intan; Arif, Idam
BERKALA FISIKA Vol 12, No 3 (2009): Berkala Fisika
Publisher : BERKALA FISIKA

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Experiments were carried out to investigate the effects of various forms, sizes and materials of electrodes in the electrolytic enrichment for the determination of tritium concentration in water sample. Electrodes were made in several forms: square plate, cylinder and spiral. The electrolytic enrichment was carried out by conducting electric current to the electrodes in electrolytic cell at 150C filled with water sample, until the water volume is reduced to 10% from the initial volume. The concentrated water were then mixed with scintillate solution, and then counted using Liquid Scintillation Counter (LSC). The results show that the appropriate electrodes is nickel square plate with the recovery fraction and the enrichment factor respectively are 73.73% and 7.373

Dose Volume Product (DVP) As Descriptor for Estimating Total Energy Imparted to Patient Undergoing CT Examination Choirul Anam; Freddy Haryanto; Rena Widita; Idam Arif; Geoff Dougherty
Journal of Medical Physics and Biophysics Vol 3, No 1 (2016)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

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The purpose of this study is to expand a descriptor for estimating the total energy imparted to a patient undergoing a CT examination and to investigate its relationship to the currently used descriptor. Estimating the total energy imparted to a patient has previously been characterized by dose length product (DLP). We propose a descriptor which we call the dose volume product (DVP), defined as the product of the size specific-dose estimate (SSDE) and the volume irradiated in the patient (V). We also present algorithm to automate the calculation of DVP. There are several steps in calculating the DVP: the first is to contour the patient automatically, the second is to calculate the area of patient in every single slice, the third is to calculate the volume of the radiated part of the patient, the fourth is to calculate the water equivalent diameter (DW) automatically, the fifth is to calculate the SSDE, and the last is to calculate the DVP. To investigate the effectiveness of the algorithm, we used it on images of phantoms and patients. The results of this study show that the automated calculations of DVP for both body and head phantoms were in good agreement with theoretical calculations. The differences between them were within 2%. DVP and DLP had a linear relationship with R2 = 0.971 (slope 1099 cm2, 95% confidence interval (CI), 1047 to 1157 cm2) and R2 = 0.831 (slope 248.6 cm2: CI, 237.6 to 259.7 cm2), for thorax and head patients respectively.

Lattice-Gas Automata for Numerical Experimental Verification of Maxwell-Boltzmann Distribution Siti Nurul Khotimah; Idam Arif; The Houw Liong
Indonesian Journal of Physics Vol 12 No 3 (2001): Vol. 12 No.3, Juli 2001
Publisher : Institut Teknologi Bandung

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Lattice-gas automata model has been applied to simulate the distribution function of gas molecules. This study shows a transition of a single-component velocity distribution from its initial non-equilibrium to its final equilibrium. The distribution is independent of time when the system reaches its equilibrium. For a sufficiently dilute gas in equilibrium, the distribution function of x-velocity component is a Maxwell-Boltzmann distribution with its average velocity component is between zero and 3% of its maximum value. This numerical experiment also obtained that the speed distribution for two-dimensional problem is a Maxwell-Boltzmann distribution. From 12 trials, average and root mean square speeds are (8.6±0.3) and (9.7±0.3) lattice units per time step respectively. We introduce a factor β to converse the unit of speed to be in meter per second. Therefore, the absolute temperature (in Kelvin) of the experiment is expressed in the mass of one molecule and Boltzmann constant as (47,1±3,2)β2 m/k.

Study on Annual Internal Radiation Dose from Consumption of Sweet Potatoes Contaminated by 134 Cs Idam Arif; Siti Nurul Khotimah; Octolia Tobigasa Tambunan; Poppy Intan Tjahaja
Indonesian Journal of Physics Vol 21 No 1 (2010): Vol. 21 No. 1, January 2010
Publisher : Institut Teknologi Bandung

The transfer of 134Cs from soil to sweet potato crops has been investigated. Sweet potato crops were cultivated in soil contaminated by 134Cs with concentration of 167.62 Bq/g as well as in non-contaminated soil as control. The 134Cs activity concentrations of leaves, stems, roots, tubers and the whole plant were determined every week up to 16 weeks. 134Cs activity concentrations of soil in root zone and outside root zone were also determined. The maximum transfer factor for the whole sweet potato plants takes place at the second week with TF value of 1.277. The maximum TF value for each parts are roots (18.448), tubbers (13.153), stems (1.241), and leaves (0.746). Annual equivalent dose was calculated based on the activity of sweet potato plants at harvest time. This research obtained annual internal radiation dose from consumption of sweet potatoes contaminated by 134Cs of 0.0185 mSv/year. This value compared with average annual dose limits recommended by BAPETEN, IAEA and ICRP respectively was 0.14%, 0.37%, and 0.19%.

Calculation Procedure for Dynamic Condition of Ion Composition in Cell Walls Altered by Proton Fluxes Idam Arif
Indonesian Journal of Physics Vol 22 No 3 (2011): Vol. 22 No. 3, July 2011
Publisher : Institut Teknologi Bandung

The calculation procedure has been developed to determine the dynamic condition of the ion composition in cell walls during proton extrusion, known as the Weak Acid Donnan Manning (WADM) model for fluxes. In this model, the walls of plant cells are considered as a system containing weak acid polymers where the interaction of ions obeys the Manning condensation theory and the Donnan theory. When protons are transported across the walls during proton fluxes, the transported proton will interact with the wall ions and alter the ion composition. This depends on the wall parameters such as the concentration of ionisable sites, the pK of the wall weak acid, and the wall linear charge density parameter. When the linear charge density parameter is still higher than the reciprocal of the highest valence of the involve cations, the transported protons during proton fluxes will decrease the wall pH, alter the ion composition in the wall Donnan free space and water free space, and release the condensed cations. Therefore some of the proton fluxes are represented by the flux of the condensed cations outside the walls. However when the linear charge density parameter is less than the reciprocal of the highest valence of the involve cations, there is no condensed cations in the walls so that the transported protons only alter the ion composition in the wall Donnan free space and water free space.

Permeability and Porosity of Two-Dimensional Porous Media Microchannels using Lattice Gas Cellular Automata Siti Nurul Khotimah; Bergas Bimo Branarto; Sparisoma Viridi; Idam Arif
Indonesian Journal of Physics Vol 23 No 1 (2012): Vol. 23 No. 1, July 2012
Publisher : Institut Teknologi Bandung

In this study, lattice-gas cellular automata were used to solve the flow of incompressible Newtonian-fluid in porous media microchannels. We discuss fluid flow between two stationary parallel plates. By applying a constant pressure gradient, volumetric flux was determined as a function of time until a steady condition is achieved. For steady laminar flow, its velocity profile is parabolic. For flow in porous media between two stationary parallel plates, the results show that medium permeability depends on porosity and obstacle configurations. For a single obstacle, the permeability is a parabolic function with respect to positions of an obstacle in the direction perpendicular to the flow. The permeability is smallest when the obstacle is at the central line along the flow. A maximum permeability may be achieved when the obstacles attached to the channel wall. Other obstacle structures give lower permeability, even zero permeability for dead end microchannels.

ISOLASI DAN IDENTIFIKASI BAHAN AKTIF PENYEBAB PEMANCARAN CAHAYA PADA BAKTERI Photobacterium phosphoreum YANG DIISOLASI DARI CUMI LAUT JEPARA INDONESIA Ratnawulan, Ratnawulan; Pringgenis, Delianis; Arif, Idam
Makara Journal of Science Vol. 9, No. 1
Publisher : UI Scholars Hub

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Isolation and Identification of Active Compound Cause Light Emmitting of Bacterial Photobacterium phosphoreum Isolated from the Indonesia Jepara Marine Squid. This research carried out to study the bioluminescence process of bacterial Photobacterium phosphoreum isolated from Indonesia marine squid. The method used in the present study involved isolation, purification, electrophoresis, and the absorbance and light intensity measurement. This result show that the luciferace enzyme of bacterial Photobacterium phosphoreum or called LBPP catalyzes the emission of visible light from the reaction of reduced flavin mononucleotide (FMNH2 ), molecular oxygen (O2 ), and an aldehyde (RCOH). The electrophoresis data show that LBPP comprised of two different subunits a and b with 41kD and 38 kD molecular weights. The absorb pattern showed that the bioluminescence process centered around 516 nm and are consistent with the fluorescence data. This result concluded that the excitation state formed after LBPP bind subtracts and the ground state formed after LBPP releases product and visible light.

ISOLASI DAN IDENTIFIKASI BAHAN AKTIF PENYEBAB PEMANCARAN CAHAYA PADA BAKTERI Photobacterium phosphoreum YANG DIISOLASI DARI CUMI LAUT JEPARA INDONESIA Ratnawulan, Ratnawulan; Pringgenis, Delianis; Arif, Idam
Makara Journal of Science Vol. 9, No. 1
Publisher : UI Scholars Hub

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Isolation and Identification of Active Compound Cause Light Emmitting of Bacterial Photobacterium phosphoreum Isolated from the Indonesia Jepara Marine Squid. This research carried out to study the bioluminescence process of bacterial Photobacterium phosphoreum isolated from Indonesia marine squid. The method used in the present study involved isolation, purification, electrophoresis, and the absorbance and light intensity measurement. This result show that the luciferace enzyme of bacterial Photobacterium phosphoreum or called LBPP catalyzes the emission of visible light from the reaction of reduced flavin mononucleotide (FMNH2 ), molecular oxygen (O2 ), and an aldehyde (RCOH). The electrophoresis data show that LBPP comprised of two different subunits a and b with 41kD and 38 kD molecular weights. The absorb pattern showed that the bioluminescence process centered around 516 nm and are consistent with the fluorescence data. This result concluded that the excitation state formed after LBPP bind subtracts and the ground state formed after LBPP releases product and visible light.

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