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K Sofjan Firdausi
Jurusan Fisika, Universitas Diponegoro, Semarang
Physics

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DETEKSI DINI KUALITAS MINYAK GORENG DAN STUDI AWAL TINGKAT KEHALALANNYA MENGGUNAKAN POLARISASI ALAMI Eva, Yulianti; Indriyani, Y; Husna, A; Putri, N Kharisma; Murni, Sri; Amitasari, Ria; Putranto, Ari Bawono; Sugito, Heri; Firdausi, K Sofjan
BERKALA FISIKA 2014: Berkala Fisika Vol. 17 No. 3 Tahun 2014
Publisher : BERKALA FISIKA

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Abstract

In this paper, we investigate natural light polarization for preliminary test of quality and authentication (halal) level of frying oil. Recently standard methods used are usually based on Indonesian National Standard (SNI), however all parameters are very difficult to be determined simultaneously. On the other hands even the test is time consumed, inexpensive, complicated and also preliminary treatments required, which is a major problem in era of rapid information need. One of an alternative solution is to use natural light polarization method. In the experiment, several vegetable frying oils and animal oils are used to be tested. The change of polarization angle is used to indicate the level of oil quality and its authentication. The result shows that higher polarization indicates lower oil quality relative to the others, which is in agreement to the previous study. This method is, not only, able to differentiate various edible vegetable oils, but also to distinguish edible oils and expired oils. More over, it has a prospect to indicate an authentication of oil that is a subject of a halal or not-halal case.This method is relative simply, not time consumed, conducted accurately without any previous treatments, and it provides a good prospect as a preliminary test for oil quality and its authentication. Keywords: Natural polarization, oil quality, halal or authentication level
STUDI UJI ALTERNATIF KUALITAS MINYAK GORENG BERDASARKAN PERUBAHAN POLARISASI CAHAYA TERIMBAS Susan, Ade Ika; Firdausi, K Sofjan; Setiabudi, Wahyu
BERKALA FISIKA Vol 14, No 4 (2011): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

AbstractIn this research, we report the quality of several cooking oils before and after heating. The parameter of quality was based on electrooptics characteristic or, so called, the change ofpolarization angle induced by external electric field. In this examination, it was used threedifferent brands of cooking oils. The samples were heated in the time interval between 0-120minutes. The electrooptics characteristic was determined by measuring the change ofpolarization angle of light as it passed through the oil while it was applied by external electricfield. The field was produced by two parallel plates connected to different potential between 0-9kV. The light source was diode laser atλ = 650 nm and λ = 532 nm. The quality of oil was then determined by average polarization angle per potential difference, i.e. α ≡ Δθ/ΔV. Based on the result of observation, the fresh oil before heated has smaller change of polarization angle thanoil after heated, which is in agreement to the previous study. The longer heating time is, morefree radicals are produced, which leads to higher polarization. It shows also that the change ofpolarization depends on the wavelength.  From two diode lasers, the effective wavelength toproduce higher number free radicals is obtained by 532 nm. The increasing average ofpolarization angle is linearly to the increasing of heating time. It is obvious that the electroopticsparameter could be proposed as an alternative quality test of cooking oil.Keyword: Cooking oil quality, Change of polarization angle, electrooptics
REVIEW PENGUJIAN HUKUM MALUS DAN SIFAT OPTIS AKTIF LARUTAN GULA MENGGUNAKAN SISTEM DETEKSI CAHAYA Amitasari, Ria; Istiyawan, Wardono; Sugito, Heri; Bawono P, Ari; Firdausi, K Sofjan
BERKALA FISIKA Vol 16, No 1 (2013): Berkala Fisika
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Abstract In this paper, we review the test results of Malus’ Law and optical activity of sugarsolution using a system light detector. Two polarizers were used in the experiment to serve thechoice of a certain direction of electric field of light and to determine the change of polarizationangle. The change of transmitted intensity were measured using LDR detector which was thenacquisitioned by microcontroller and displayed via LCD and computer using  Microsoft Visual Studio C#. The experiment result is in agreement to the Malus’ Law with correlation coefficient of 0.99, and by using the equipment we obtain linearity between the change of polarization angle andconcentration of sugar solution, which is appropriate to the theory, as well. The specific rotarypower is (54±2) o/dm(g/mL) in the experimental uncertainty.Keywords: Malus law, change of polarization angle, light detector
PEMANFAATAN SIFAT OPTIS AKTIF ALAMI UNTUK KENDALI MUTU MINYAK GORENG MENGGUNAKAN LAMPU PIJAR Asy Syifa, A Y; Nisa, Fathia; Prasanti, Irvani D; Murni, Sri; Firdausi, K Sofjan
BERKALA FISIKA Vol 16, No 2 (2013): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

In this study the properties of natural optical activity of the various vegetable cookingoils was used as a new method for a quality control and was proposed as a new prospect forpreliminary test of oil quality. The samples used were various packaging cooking oil obtained inthe shops and were considered already fulfilled by SNI. The source of light to illuminate was a75W light-bulb. The change of the polarization angle of light was measured using polarizer basedon Malus’ law, and it was used to indicate the levels of oil quality degradation. The experimentalresult shows that highest change of polarization angle indicates relative lowest quality of oils. Anolive oil shows the best oils relative from other types of vegetable oils. The natural polarization inthis case is able to differentiate between various types of oil, and to distinguish fresh oil andexpired oil. It seems that natural polarization accommodates some contributed components oflevel of degradation of oil quality, i.e. free fatty acid and saturated fat. This method provides someadvantages, such as, simple equipments, a fast test, without preliminary treatment, and accurateresults. For the future, it shows a reliable test to conduct as a previous quality control for cookingoil and replaces the role of conventional, expensive standard methods. This method offers also achallenge to evaluate the level of authentication or halal of oils and fats.Keywords: oil quality, polarization angle, optical activity.
PEMBUATAN LAPISAN FOTOKATALIS ZINC OXIDE (ZnO) DENGAN TEKNIK SPRAY COATING DAN APLIKASINYA PADA PENGERING JAGUNG Hidayanto, Eko; Sutanto, Heri; Firdausi, K Sofjan; Arifin, Zaenal
BERKALA FISIKA Vol 16, No 4 (2013): Berkala Fisika
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Abstract

ZnO thin film has been deposited on the glass with a spray coating technique. Gel of ZnO 0.5 M was synthesized by dissolving 0.5 M zinc acetate dehydrate in isopropanol andmonoethanolamine solution at room temperature with the molar ratio of MEA and ZnAc is 1:1. The solution was stirred using a magnetic stirrer at 70°C for 30 minutes to get the clear and homogeneous ZnO gel. ZnO gel is placed on the spray hole and sprayed on a heated glasssubstrate till 40oC. Then, the spraying layer spraying was allowed to stand for 3 days tostrengthen the contact with glass layer. Deposition results of ZnO layer is transparent withtransmittance values of 71.4 % and decreases with a decrease in wavelength imposed on the layer.The energy dispersive X-ray (EDX) results show the composition of zinc (Zn) is less than theoxygen (O) with a ratio Zn : O = 38.44 % : 61.56 %. The scanning electron microscopy (SEM)results show ZnO thin film has a smooth and homogeneous surface with a grain size of 57 nm. Thetest results demonstrate ZnO layer has a band gap value of 3.01 eV. The drying corn shows thatdirectly drying using sunlight has a faster rate compared using ZnO glass. Surface morphology ofthe layer of dried corn using ZnO glass has brighter color and lice compared to directly drying onsunlight.Keywords: Photocatalyst, ZnO, Thin Film, Spray Coating, Corn, Drying
KOMPARASI KUALITAS CITRA HASIL REKONSTRUKSI METODE ALGEBRAIC RECONSTRUCTION TECHNIQUE (ART) ADITIF DAN MULTIPLIKATIF (MART) PADA CT SCAN Anam, Choirul; Firdausi, K Sofjan
BERKALA FISIKA Vol 14, No 4 (2011): Berkala Fisika
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Abstract

AbstractImage recontruction for CT scan by the methods of additive ART and muliplicative ART (MART) have been carried out using Malab software. The object used is Sheep-Logan phantomwith matrix size 50x50,  used a paralel beam and  angle interval 10, 50, 10,respectively. It is obtained that additive ART produces many artifacts, while MART producesfewer artifacts. Additive ART produces a contras between objects and background with relativelyhigh, while MART produces relatively lower contrast. It is obtained that in the additive ART,interval angle affects the quality of image. This does not happen to MART. So, the MARTreconstruct CT image faster, because it can be obtained relatively good image despite the angleinterval is large.Keywords: Image reconstruction, Additive ART, Multiplicative ART (MART)
SIFAT ELEKTROOPTIS SEBAGAI PARAMETER INDIKASI MUTU BERBAGAI JENIS MINYAK GORENG KEMASAN Murni, Sri; Firdausi, K Sofjan; Hidayanto, Eko; Bawono P, Ari
BERKALA FISIKA Vol 15, No 4 (2012): Berkala Fisika
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Abstract

Abstract In this paper, we introduce the change of polarization angleβ induced by external electric field, as a quality indication of several edible oils without preliminary treatment. The averagevalue ofβ in the interval of applied potential difference plays important role as level of number offree radicals produced in the edible oils. The samples used were olive oil, extra olive oil, palm oil,and corn oil. Theβ value was obtained by measurement of the change polarization angle as the function of magnitude the electric field on the samples. The electric field was produced by DCvoltage power supply on two parallel plates in a separated distance of 2.5 cm and in area of 5 cm× 3 cm. The source of light used was He-Ne laser 1 mW (λ=633 nm). The experiment result showsthat for all the fresh frying oil samples the polarization angle has value between 2.3× 10/V and3.3× 10-4 0/V in the experimental condition. The extra olive oil has the smallest value while palmoil has the greatest. According to the previous study, the olive oil is relatively the best oil.Keywords: frying oil, electrooptics, polarization angle
EVALUASI KUALITAS BEBERAPA JENIS MINYAK GORENG KEMASAN SETELAH DIPANASKAN MENGGUNAKAN SIFAT ELEKTROOPTIS Murni, Sri; Bawono Putranto, Ari; Hidayanto, Eko; Firdausi, K Sofjan
BERKALA FISIKA Vol 16, No 3 (2013): Berkala Fisika
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Abstract

In this report, we have determined the average value of polarization angle for various edible oils, before and after heating. The change of polarization angle was measured averagebetween potential differences 0-9 kV. The heating time for the samples was conducted up to 10 hours at average temperature by 180°C. The source of light was He-Ne Laser 1 mW (633 nm) with optical length of samples of 1 cm. In agreement to the previous experiment, our result shows that all vegetable oils provide increasing of free radicals indicated by increasing polarizationangle for longer heating time. For the heating time interval 0-10 hours, the level degradation ofoil rises quadratically. From various edible oils, olive oil is still the relative best quality from allsamples in this experiment. This method, once again, shows more powerful relative to otherstandard methods.Keywords: frying oil, electrooptics, polarization angle
STUDY OF ELECTROOPTICS BEHAVIOUR OF NAPHTHALENE AND ANTHRACENE Firdausi, K Sofjan; Khumaeni, Ali; Richardina, Very; Arianto, Fajar; Budi, Wahyu Setia
BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
Publisher : BERKALA FISIKA

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Abstract

In this paper, we demonstrate electro-optics behaviour of naphthalene and anthracene using change of polarization of sample induced by external electric field. The source of light for polarization was 1 mW-he-ne Laser 633 nm. The induced external Electric field was produced by high DC voltage 0 – 7 kV. The samples were diluted in solutions-form using wash-benzene. The result shows that anthracene has higher polarizability than naphthalene, which is indicated by higher change of polarization in anthracene than naphthalene. The Assumption that potential difference is proportional to the distance between molecules is shown qualitatively by graphs of Van der Waals potential energy or force between molecules. In this case, anthracene has higher level Energy than naphthalene so that it can be used in visible excitation for environmental spectroscopy. Keywords: electro-optics, polarization, naphthalene, anthracene, Van der Waals potential energy 
PEMBUATAN KURVA ISODOSIS PAPARAN RADIASI DI RUANG PEMERIKSAAN INSTALASI RADIOLOGI RSUD KABUPATEN KOLAKA - SULAWESI TENGGARA Syahria, Syahria; Setiawati, Evi; Firdausi, K Sofjan
BERKALA FISIKA Vol 15, No 4 (2012): Berkala Fisika
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Abstract

t have been conducted research about the influence of distance variability betweensecondary radiation source and the determining spot to scatter  radiation exposure in theinspection room I radiology instalation RSUD Kolaka – South East Sulawes, it producted isodosecurve .This research use phantom, in the form of water in the plastic container high 40 cm andwidth 21 cm, with exposure wide 30×  40 cm. Exposure condition is given by fixed expose factor covering of tube voltage 90 kV, tube current 150 mA and exposure time 0.8 second.  Sample in this research is distance of 1 meter; 1,5 meter and 2 meter from the secondary radiation source to thedetermining spot, which measuring the scatter radiation exposure is directly conducted by thesurvey meter measuring instrument.The result of research indicates that the amount of thescattered radiation exposure will downhill progresivley to addition distance, so it can know thepoints/places that safe to the scatter radiation exposure. It can also know the maximum time limitallowed for a radiator worker in the inspection room I.Keywords : Isodose Curve ,  Phantom, Expose factor, Scatter radiation exposure.
Co-Authors A Husna, A A Y Asy Syifa Ade Ika Susan Ali Khumaeni Ari Bawono P Ari Bawono Putranto Choirul Anam AM Diponegoro Eko Hidayanto Evi Setiawati Fajar Arianto Fathia Nisa Heri Sugito Heri Sutanto Irvani D Prasanti Kuwat Triyana N Kharisma Putri, N Kharisma Ria Amitasari Sri Murni Syahria Syahria Very Richardina Wahyu Setia Budi Wardono Istiyawan Y Indriyani, Y Yulianti Eva, Yulianti Zaenal Arifin