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INDONESIA
SAINS DAN MATEMATIKA
Published by Universitas Diponegoro
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Articles 5 Documents
Search results for , issue "Volume 19 Issue 1 Year 2011" : 5 Documents clear
Pembuatan Zeolit Nanopartikel dengan Metode High Energy Milling (Zeolite Nanoparticle Fabrication using High Energy Milling Method) Muhriz, Mohammad; Subagio, Agus; Pardoyo, Pardoyo
JURNAL SAINS DAN MATEMATIKA Volume 19 Issue 1 Year 2011
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

Pembuatan nanopartikel menggunakan metode high energy milling belum banyak dilakukan di Indonesia. Tujuan dari penelitian ini adalah membuat zeolit nanopartikel dari zeolit alam dengan metode high energy milling. Zeolit alam Wonosari digerus dan diayak menggunakan ayakan 250 mesh dan kemudian digiling dengan High Energy Milling-Ellipse 3D Motion (HEM-E3D) selama 0, 2, 4, dan 6 jam dengan kecepatan 1000 rpm dan ball to powder ratio (BPR) sebesar 8:1. Bentuk fisis dari zeolit sebelum dan sesudah milling terlihat sama dan sulit dibedakan. Hasil karakterisasi SEM menunjukkan adanya penurunan ukuran partikel dari Z-0 menjadi Z-6. Zeolit dengan waktu milling Z-6 mempunyai ukuran partikel terkecil yaitu sebesar 70-280 nm Karakterisasi dengan metode BET menunjukkan zeolit beraglomerasi yang ditandai dengan tidak adanya perubahan berarti pada luas permukaan spesifik, volume pori total, dan ukuran pori rata-rata semua sampel.   Keywords: high energy milling, zeolit alam, ukuran partikel
Zooplankton Diversity and Abundance in Shrimp Pond Ecosystem in the Presence of Sargassum plagyophyllum and Gracilaria verrucosa Izzati, Munifatul
JURNAL SAINS DAN MATEMATIKA Volume 19 Issue 1 Year 2011
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

We studied zooplankton community structure in defferent ecosystem type where different species of aquatic plants are presented. The different in zooplankton community structure can be attributed to different aquatic plant species. We used two different species of aquatic plants, Sargassum plagyophyllum and Gracilaria verrucosa in shrimp pond ecosystem. Every aquatic plant species were replicated three times, and three enclosures without aquatic plant were used as controls. The different in morphological complexity of aquatic plant may affect zooplankton community structure. Our results indicated that the presence of aquatic plant differ in affecting zooplankton community structure. In general, pond with aquatic plant indicate more abundant and diverse of zooplankton. In the presence of Sargassum zooplankton was more abundant compared to the presence of Gracilaria. Whereas with Gracilaria, zooplankton biodiversity index were higher than with Sargassum.   Keywords: zooplankton, sargassum plagyophyllum, Gracilaria verrucosa.
Simulasi Pengaruh Kombinasi Target-Filter Tambahan Terhadap Spektrum Sinar-X pada Tabung Pesawat Mammografi dengan Program EGSnrc Budiwati, Trisna; Anam, Choirul; Setiawati, Evi
JURNAL SAINS DAN MATEMATIKA Volume 19 Issue 1 Year 2011
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

The mammography use the specific x-ray energy. At high x-ray energies (>35 keV) the subject contrast between the normal and malignant tissues in the breast is poor, at very low x-ray energies (10-15 keV) the contrast is highest, however the high absorption result in a high tissue dose. To achieve to good result must be used the optimal energy, that could be achieved by using specific x-ray target and additional filter materials to generate characteristic x-ray of the desired energy. This research was aimed to evaluate the influence of target-additional filter combination and filter thickness to the x-ray energy spectrum. The research was conducted by Monte Carlo simulation using EGSnrc program. The model of mammography tube was designed by BEAMnrc program, and phase space file was resulted by BEAMnrc was analyzed by BEAMDP. The tube x-ray contained of target and additional filter from molybdenum (Mo) and rhodium (Rh) material, window from berrylium, and collimator from Pb. Target-additional filter combination were Mo-Mo, Mo-Rh, Rh-Rh and Rh-Mo.  Variation of additional filter thickness that be used are 0,001 mm; 0,03 mm; and 0,05 mm. The results of the simulation indicated that an x-ray consist of bremmstrahlung and characteristic. X-ray spectrum were produced by Mo target had characteristic x-ray energy 17 keV and 19 keV, and Rh target had characteristic energy 20 keV and 23 keV. Target-additional filter combination that allowed are Mo-Mo, Mo-Rh, and Rh-Rh combination. Rh-Mo combination could not be used, because Mo filter would attenuated x-ray characteristic energy. For the Mo-Mo and Rh-Rh, the thicker the additional filter then the x-ray spectrum obtained has a more narrow, but the reduced intensity of the x-ray bremmstrahlung and characteristic.   Keywords: target-filter combination, x-ray spectrum, mammography, EGSnrc.
Konstruksi Greedy Kode Lexicographic untuk Membangun Perluasan Kode Golay (24 12,8) Aini, Aurora Nur; Irawanto, Bambang
JURNAL SAINS DAN MATEMATIKA Volume 19 Issue 1 Year 2011
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

Golay codes can be constructed by lexicographic codes. Lexicographic codes constructed by Greedy algorithm. Greedy construction is one type of Greedy algorithm. Given codes with minimum distance d and length n. To construct the greedy algorithm, the codeword with length n are processed in some fixed order, and the next codeword is inserted in the code when its distance from all codewords previously selected is  d. On Greedy construction, to set (n, k,d) codes, we only need to set (n-k,k) codes with  k iteration.   Keywords: linear codes, lexicographic codes, Golay, generator matrix
Komunitas Fitoplankton Danau Rawapening Soeprobowati, Tri Retnaningsih; Suedy, Sri Widodo Agung
JURNAL SAINS DAN MATEMATIKA Volume 19 Issue 1 Year 2011
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

Fitoplankton merupakan produsen primer perairan, sehingga keberadaannya sangat penting untuk tingkatan trofik di atasnya. Komunitas fitoplankton sangat ditentukan oleh kualitas perairan, sehingga fitoplankton dapat digunakan sebagai bioindikator kualitas perairan. Tekanan lahan di bagian hulu merupapan problem utama Danau Rawapening.Volume air Danau Rawapening cenderung menurun sebagai akibat sedimentasi yang cukup tinggi, sehingga mengganggu fungsi utamanya. Penelitian ini bertujuan mengkaji komunitas fitoplankton Danau Rawapening. Pengambilan sampel dilakukan pada 7 lokasi di Danau Rawapening. Identifikasi fitoplankton dilakukan menggunakan SRC dan mikroskup perbesaran 400 – 1.000 kali. Dijumpai 58 spesies fitoplankton dengan dominansi Bacillariophyta. Berdasarkan keanekaragaman fitoplankton, maka ekosistem Danau Rawapening kurang stabil – cukup stabil. Dominannya Aulacoseira granulata mengindikasikan kondisi eutrofik danau. Penelitian perlu dilanjutnya pada musim dan waktu yang berbeda.   Keywords: fitoplankton, Danau Rawapening, eutrofik, bioindikator

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