Judul: Produksi protein empat isolat ganggang mikro asal air tawar dan sawah pada skala laboratorium dan lapang: pengaruh konsentrasi hara media
Abstrak: Results of previous studies proved that some types of microalgae have a high growth and high protein content, so it is potential to be cultivated as a source of forage and food substitutes. Protein content is different in each type of micro algae. This research was conducted to determine the optimum composition and concentration of nutrients in the media for cultivating each of the 4 microalgae isolates studied at laboratory scale as well as evaluating their protein content at field scale with 2 days-harvest interval. The study was begun with the cultivation of 4 microalgae isolates (ICBB 9111, ICBB 9112, ICBB 9113, and ICBB 9114) at a laboratory scale each in 50 ml of media with 5 different concentrations. Concentrations of the 5 media tested were: 0.75 times the M4 standard media composition (0.75 M4), M4, 1.25 M4, 1.50 M4, and 1.75 M4. Composition of the M4 standard media used was (g/L): 1.5 NaNO3, 0.049 K2HPO4, 0.0366 MgSO4, 0.0271 CaCl2, 0006 Citric Acid, 0006 Fe-Ammonium Citrate, 0.001 EDTA, 0.02 Na2CO3, and 1 ml micro nutrient with a composition of (g/L): 2.86 H3BO3, 0.1485 MnCl2, 0.1245 ZnSO4, 0.0506 Na2MoO4.2H2O, 0056 CoCl2.6H2O and 0.043 CuSO4. The results of this study indicated that the optimum growth rate at laboratory-scale of the 4 microalgae isolates studied was achieved at different media concentrations: for ICBB 9111 and ICBB 9113 isolates was at the M4 standart media, whereas for isolates ICBB 9112 and ICBB 9114 was at 0.75 M4. These optimum media concentrations were then used for cultivating each isolate at the field scale. Cultivation of the 4 microalgae isolates investigated at the field scale with an harvest-interval of 2 days produced different biomass weight. The average dry biomass production of isolates ICBB 9111, ICBB 9112, ICBB 9113 and ICBB 9114 were, respectively, 0.28, 0.21, 0.26 and 0.32 g/L. These dry biomass were then used to analyze the protein content. The highest protein content was obtained from the isolate ICBB 9114 with an average level of 33.99%, while the lowest one was from the isolate ICBB 9113 with an average level of 26.05%. Variations in biomass and protein production indicated the effects of isolate types of microalgae, rate of nutrients utilization or metabolism and environmental factors.
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Judul: Produksi lipid dan karbohidrat ganggang mikro asal sawah dan perairan tawar yang dikultivasi pada skala lapang
Abstrak: Production of bioenergy as an alternative for oil fuel requires biomass as raw material. With an extremely rapid growth rate, microalgae is potential to be developed as a source of bioenergy by extracting lipids and carbohydrates from its biomass. This research was initiated by a laboratory-scale cultivation of 4 isolates of microalgae (ICBB 9111, ICBB 9112, ICBB 9113, and ICBB 9114) in 50 ml medium with 5 different concentrations, i.e. 0.75 times the standard media M4 composition (0.75 M4), M4, 1.25 M4, 1.50 M4, and 1.75 M4. The composition of M4 standard media (g/L): 1.5 NaNO3, 0.049 K2HPO4, 0.0366 MgSO4, 0.0271 CaCl2, 0.006 citric acid, 0.006 Fe-ammonium citrate, 0.001 EDTA, 0.02 Na2CO3 and 1 ml micro nutrient with composition (g/L): 2.86 H3BO3, 0.1485 MnCl2, 0.1245 ZnSO4, 0.0506 Na2MoO4.2H2O, 0.0506 CuSO4, and 0.043 CoCl2.6H2O. The laboratory scale growth-rates of microalgae at different compositions of standard media were varied. Based on the results of analysis of variance, Duncan's Multiple Range Test, and growth chart, the optimum medium for the field-scale cultivation were 0.75 M4 for microalgae ICBB 9112 and ICBB 9114, and M4 for microalgae ICBB 9111 and ICBB 9113. The growth rate of microalgae at field scale was faster than those at laboratory one. The average biomass productivity of microalgae ICBB 9111, ICBB 9112, ICBB 9113, and ICBB 9114 after cultivated for 2 days at field scale were, respectively, 0.28, 0.21, 0.26, and 12.32 g/L. The highest lipid production was produced by isolate ICBB 9114 (32% w/w) at 0.75 M4 medium, and the highest carbohydrate production was obtained from isolate ICBB 9113 (44% w/w) at M4 media. This result indicates that when the microalgae lipid production is high, the corresponding carbohydrate production is lower and vice versa.
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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