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: Studi Produksi Bioetanol untuk Peningkatan Budidaya dan Nilai Tambah Pascapanen Sagu (Metroxylon spp.) Asal Sorong
Abstrak: Sago (Metroxylon spp.) is a potential starch-producing crop which produce 20 – 40 tonnes starch ha-1 year-1. Each years, big amount of sago starch are wasted because it is not exploited well. The people only utilize sago starch for consumption in daily food needs. The low utilization of sago reduces its harvest performances. Sago starch can be used as raw material for renewable alternative energy such as bioethanol. The main object of this study is to analyze the optimation of enzyme application to hydrolyze sago starch that were collected from Sorong and the ratio of water with starch usage in bioethanol fermentation. The second aim is to ensure the kind of sago starch that can be used to produce bioethanol, so that it becomes the driving force for sago farmers in the cultivation of sago intensively in Sorong District. This study was used enzyme to hydrolyze sago starch into liquid sugar. Fermentation of liquid sugar used yeast contained Saccharomyces cereviseae until it produces bioethanol. The sago starch are used in this study that is Iwarwo type. The highest etanol content was 10.93% at 72 hours after fermentation. The result was collected from condition of 1:5 sago starch with water ratio treatment, 1 mL of α-amylase enzyme kg-1 sago starch and 1.2 mL glucoamylase enzyme kg-1 sago starch.
Keyword: bioethanol, hydrolysis, optimation, sago starch, Sorong

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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