Judul: Penggunaan sterilisasi iradiasi Sinar Gamma Co-60 dan Mesin Berkas Elektron pada viabilitas inokulan dalam bahan pembawa (kompos dan gambut)
Abstrak: Carrier material is very important role to decide the quality of biological fertilizer. The carrier consist of high amount of indigenous microbes about 106 cell/gram carrier even more. Therefore, sterilization of carrier material either for kill or reduce the amount of indigenous microbe is the absolutely thing to do. There are several factors in carrier sterilization, such as sterilization activity, sterilization cost, and sterilization process effect of carrier type. This research used some of sterilization methods, there were Gamma Ray Irradiation C0-60 method and Electron Beam Machine (EBM) method at 50 kGy. Both of them are compared with autoclave method which is conventional method at temperate 121oC for one hour on two days in a row. The carriers that used in this research were compost product of BATAN and peat from South Kalimantan. in testing the ability of inoculants survival (Azotobacter, Azospirillum, Phosphate Solublizing Fungi), they are added in the sterilized carriers and they are saved at 20oC. and then we do counting the inoculants population periodicly until ten weeks. Gamma Ray Irradiation Co-60, Electron Beam Machine, and autoclave the same method to kill indigenous microbes. Whereas from inoculant viability tests, The Effect of Gamma Ray Irradiation Co-60 and Electron Beam Machine to carriers is better than autoclave because this method only give good effect to carrier (peat) less than six weeks, where contaminant will not found visually. On the other hand the Gamma Ray Irradiation Co-60 and Electron Beam Machine carriers still have good condition until ten weeks.
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Judul: Efektivitas sterilisasi iradiasi sinar gamma CO-60 dan mesin berkas elektron terhadap berbagai bahan pembawa serta viabilitas inokulan dalam bahan pembawa arang batok dan zeolit
Abstrak: Biofertilizer is a substance containing living microorganism such as nitrogen fixing bacteria, phosphate solubilizing microorganism and organic matter decomposing microorganism which applied to seed, plant surface or soil to improve growth and increasing supply of availability of primary nutrients to the plant. Application of biofertilizer becomes alternative fertilizer to support application of chemical fertilizer to preserve the environment. Biofertilizers are packaged on carrier material such as peat, charcoal, compost, zeolite and others which can provide ideal home and keep the effectiveness of microorganism during storage period. Carrier is important thing to determine the quality of biofertilizer. The property of good carrier is free for unwanted indigenous microorganism to keep high number of inoculants microorganism, so that must be carrier sterilization. The purpose of this research was to investigate the effectiveness of Gamma Irradiation Co-60, Electron Beam Machine (EBM) and autoclave toward decreasing the number of indigenous microorganism on carrier material coconut shell charcoal, zeolite, wood charcoal and peat from Rawa Pening. Beside that to investigate viability of Azospirillum, Azotobacter and Phosphate Solubilizing Fungi inoculants on carrier material coconut shell charcoal and zeolite. Sterilization of Gamma Irradiation Co-60 and EBM conducted in PATIR – BATAN, while sterilization of autoclave, sterility tests and viability tests conducted in Laboratory of Soil Biotechnology, Agricultural Faculty, IPB. The result shows using Gamma Irradiation Co-60 at 50 kGy, Electron Beam Machine (EBM) and autoclave are effective to sterilize indigenous microorganism on carrier materials with minimum detection limit was 102 cfu/g. The result of viability of Azospirillum, Azotobacter dan Phosphate Solubilizing Fungi inoculants on sterilized carrier material by Gamma Irradiation Co-60, EBM and autoclave tended to decline during storage 70 days at room temperature (250C). Viable cell Azospirillum inoculants on zeolite sterilized by Gamma Irradiation Co-60 and autoclave give best performance of viability test with decreased number of cell were 11.11 %. While using autoclave toward coconut shell charcoal leads to decrease viable cell of Phosphate Solubilizing Fungi inoculants to 99.75 % aimed that autoclave was not best method of sterilization.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf