Judul: Process engineering of hydrolysate production from sago hampas as substrate for bioethanol production
Abstrak: Sago hampas is one abundant biomass available in Indonesia, because Indonesia has more than half (56.5%) of world sago forest. The research objective was to obtain a high sugar hydrolysate from sago hampas, as a substrate for production of bioethanol. The study was done in four phases: 1) Analysis of sago hampas biomass and its pretreatment, 2) Hydrolysis of sago hampas starch using hydrothermal enzymatic method and using 0.25 M H2SO4 solution as a comparison, 3) Conversion of sago hampas cellulose into glucose using Trichoderma reesei, and 4) Application of hydrolysate from sago hampas for bioethanol production and its added value analysis. Results showed that the largest contain of sago hampas was starch followed by cellulose. Pretreatment of sago hampas using distilled water at 115 oC for 15 minutes gave the highest starch content of 17.98 g/L (the yield of 87.24%). In the other hand, treatment with 0.25 M H2SO4 at 115 oC for 15 minutes gave the highest total sugar at 20.23 g/L in the extract (88.16% conversion factor). Sago hampas starch in extract was then converted by enzymatic method to sugar with the highest dextrose equivalent result of 86.56%. Conversion of sago hampas cellulose into glucose was carried out by Trichoderma reesei in Erlenmeyer flask using water bath shaker, resulting in 0.3 g/L glucose. Glucose produced seems to be repressor for further cellulase production, which is known as glucose effect. Bioethanol concentration obtained from sugar hydrolysate using hydrothermal enzymatic method was slightly higher compared to bioetanol concentration obtained using 0.25 M H2SO4 method, i.e 2.82% and 2.65% respectively. Added value obtained from sago hampas hydrolysate production using hydrothermal enzymatic method with cellulose residue as by-product was about Rp. 444.79 for each kg of output with 41.54% of added value ratio. Production factor compensation for businnes owner, worker and other input price were 41.06%, 7.25% and 51.69% respectively.
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Judul: Sakarifikasi Empulur Sagu (Metroxylon sagu) dengan Konsorsium Enzim Amilolitik dan Holoselulolitik untuk Produksi Bioetanol
Abstrak: Starchy materials such as sago in bioethanol production is one effort in finding solutions to the depletion of fossil fuel reserves but leaving a large amount of wastes. In this research, native sago pith was used directly for bioethanol production. Sago pith is heterogeneous substrates that need pretreatment to reduce the level of crystallinity of fibers and dissolve the starch; also required a number of enzymes to hydrolyze. This research aim is to determine the effects of microwave treatment and consortia of enzymes (α-amylase, amyloglucosidase and pullulanase, cellulase and xylanase) in fermentable sugar production process from the pith of sago palm and its utilization for bioethanol production. This study included the preparation of raw materials sago pith, pith composition analysis including proximate components, starch, amylose and the composition of fiber (cellulose, hemicellulose, and lignin), characterization and preparation of enzymes for determining the optimum temperature, the process of hydrolysis and characterization of syrup. Furthermore, the results of hydrolysis are used in the production of bioethanol in batch and closed systems. The results showed that, microwave treatment made starch easy to swell and break the crystalline structure of fiber. Enzymes consortia in saccharification increased the fermentable sugar production but S. elippsoides used tend to convert glucose into organic acids in spite ethanol.
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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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