Judul: Produksi Bioetanol Dari Sirup Glukosa Ubi Jalar (Ipomoea batatas L) Secara Fed Batch Dengan Menggunakan Saccharomyces cerevisiae
Abstrak: Ketersediaan pasokan energi khususnya bahan bakar fosil merupakan salah satu permasalahan yang dihadapi oleh Indonesia. Cadangan minyak bumi Indonesia semakin menipis sedangkan jumlah kebutuhan bahan bakar semakin meningkat dan diperkirakan akan habis 23 tahun ke depan jika tidak ditemukan sumber energi baru. Indonesia merupakan salah satu negara pengimpor bahan bakar minyak. Kebutuhan bahan bakar minyak di Indonesia mencapai 215 juta liter per hari sedangkan produksi dalam negeri 178 juta liter per hari dan kekurangannya 40 juta liter per hari harus diimpor. Pengembangan bioenergi merupakan salah satu alternatif untuk meningkatkan pasokan energi. Indonesia memiliki kondisi iklim dengan curah hujan yang cukup, sinar matahari sepanjang tahun, ketersediaan lahan yang luas, keanekaragaman hayati, sumber daya manusia, sumber daya alam sehingga potensial untuk pengembangan bioenergi. Salah satu sumber bahan baku bioenergi adalah ubi jalar sebagai sumber bahan baku bioetanol untuk subtitusi bensin. Ubi jalar memiliki umur panen yang relatif singkat yaitu antara 3-3.5 bulan dengan produktivitas mencapai 40 ton/ha. Beberapa penelitian telah dilakukan tentang pembuatan bioetanol dari ubi jalar dengan kadar etanol yang dihasilkan sebesar 9-21%. Melalui penelitian ini dilakukan pembuatan bioetanol dari sirup glukosa ubi jalar dengan mengkaji potensi bahan baku ubi jalar dalam pembuatan sirup glukosa sebagai bahan baku pembuatan bioetanol serta melalukan rekayasa bioproses pada sistem fed batch dengan perubahan sistem pertumbuhan Saccharomces cerevisiae dari kondisi aerobik menjadi anaerobik serta variasi konsentrasi substrat yang diumpankan pada sistem fed batch terekayasa. Sehingga melalui penelitian ini diharapkan dapat menghasilkan rendemen bioetanol yang lebih tinggi dengan kandungan gula sisa yang rendah.
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Judul: Pembuatan Bioetanol Dari Dekstrin Dan Sirup Glukosa Sagu (Metroxylon Sp.) Menggunakan Saccharomyces Cerevisiae Var. Ellipsoideus
Abstrak: There are some factors of fossil fuel problems in Indonesia namely the decreasing of fossil fuel production, the increasing of domestic energy consumption, the high price of fossil fuel and the harmless of fossil fuels itself to the environment. The research of energy alternative source should be carried out as an effort to reduce the energy supply based on fossil fuels. Bioenergy is the main alternative to overcome the energy crisis based on fossil fuel. Bioenergy is one of alternatives energy based on biomass derivate; material from living organism (plants, animals and microorganism). The development of the bioenergy is absolutely appropriate to be implemented in Indonesia because it is supported by the abundant of natural resources potency and also the availability of the field. One of bioenergy which can be developed is bioethanol which can replace the use of gasoline. The main purpose of this research was to produce bioethanol from sago starch by using Saccharomyces cerevisiae var. ellipsoideus in batch system. The particular purposes of this research were to determine the kind of substrate and substrate sugar concentration based on yield of ethanol produced and value of biomass, and also its influence to the other fermentation parameters (total residual glucose and pH). Besides that, this research was also aimed to know the influence of process manipulation (full agitation dan stop agitation) towards ethanol yield, biomass quantity, total residual glucose and pH. Saccharomyces cerevisiae var. ellipsoideus can utilize dextrin and glucose syrup to produce biomass and ethanol. Fermentation of glucose syrup 24 % using Saccharomyces cerevisiae var. ellipsoideus for 24 hours produce the highest amount of biomass 2,84 g/l and the highest ethanol yield 28,3 g/l. At the 6th hour, the yeast is still in log phase, but at 12th hour it had been in stationary phase. The total residual glucose and pH were decreasing during fermentation process. Bioprocess manipulation was carried out by using glocose syrup 24 % as substrate and stopped the agitation at 6th hour. Ethanol and biomass quantity produced by full agitation was higher than that produced by stop agitation at 6th hour. The full agitation could produce ethanol up to 26,96+1,80 g/l and stop agitation at 6th hour could produce ethanol up to 21,21+2,83 g/l. At the 24th hour, the average of pH values on full agitation was 3,22+0,02, meanwhile the mean of pH values on stop agitation at 6th hour was reached at 3,23+0,00. The lower of pH values could inhibit the microorganism growth. The values of Y x/s, Y p/s dan Y p/x on full agitation were 0,04+0,00, 0,41+0,00 and 10,41+0,34, meanwhile on stop agitation at 6th hour were 0,04+0,00, 0,34+0,07 and 9,48+1,45. The agitation stopped at the 6th hour caused inhomogeneous condition so the process of fermentation was not well done.
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Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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