Judul: Degradation of Petroleum Hydrocarbon on Petroleum – Polluted Soil by A10 and D8 Isolates.
Abstrak: Petroleum pollution could come from spilled oil during drilling, production, refining, and transportation activities. One way to overcome petroleum pollution is by bioremediation method. Bioremediation is a natural environment recovery that utilize microorganism activity to degrade hazardous organic compounds to other compounds like carbondioxide, water, biomass, and side products that are simpler than the original compounds. This research used exogenous bacteria isolates of A10 and D8 as subjects of the process. These isolates applied on 5% (w/w) crude oil contaminated soil. Crude oil hydrocarbon residue was measured using gravimetric method. During five weeks, D8 isolate was able to decrease crude oil contaminant up to 92.30% and A10 isolate up to 60.23%. The gas chromatography-mass spectrophotometry analysis showed that A10 and D8 isolates degraded crude oil by changing the oil compounds become shorter chains.
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Judul: Perombakan Hidrokarbon Dalam Tanah Terkontaminasi Minyak Berat, Minyak Ringan dan Oli Bekas oleh Bacillus sp.
Abstrak: Oil is the main source of energy for humans activities such as industries and transportations. The oil exploration activities have potential to pollute the environment (i.e.soil, water, and air). The sludge released bysuch activities can be degraded by bacteria into non-harmful compounds. Biodegradation process is done to achieve the concentration of Total Petroleum Hydrocarbon (TPH) in the contaminated soil less than 1%. The result showed that the bacteria of Bacillus sp. ICBB 7859, ICBB 9461, ICBB 5071 were able to degrade the concentration of TPH of heavy oil from 9.5082% to 0.4673%, 10.7747% to 0.3607% and 9.2442% to 0.6713%, respectively. The three isolates of bacteria needed nine weeks to complete the process. For light oil, Bacillus sp. ICBB 7859 was able to decrease the TPH from 2.9407% to 0.4378%, ICBB 9461 from 3.1433% to 0.4702%, and ICBB 5071 from 3.0742% to 0.5991% respectively, within four weeks. For iv lubricant wastes, Bacillus sp. ICBB 7859 was able to decrease the TPH of lubricant wastes from 7.6949% to 0.9067, ICBB 9461 from 7.4556% to 0.9222%, and ICBB 5071 from 7.3459% to 0.6796% respectively. The three isolates of bacteria completed the degradation process in different time. Bacillus sp. ICBB 7859 and ICBB 9461 degraded lubricant wastes within six weeks, and Bacillus sp. ICBB 5071 degraded the lubricant wastes within five weeks to reach the TPH concentration of less than 1%.
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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