Judul: Rekayasa Bioproses Produksi Bioetanol dari Hidrolisat Pati Sagu (Metroxylon sp.) Menggunakan Saccharomyces Cerevisiae Var.ellipsoides Pada Kultivasi Nir-Sinambung dan Semi Sinambung:
Abstrak: Starch of sago is one of the sources of ethanol which is able to be produced by enzymatic hydrolysis and followed by cultivation process. It has high concentration of carbohydrate (80 %), so it can produce glucose highly with enzymatic hydrolysis process. The total amount of glucose has correlation with amount of ethanol, in cultivation process. The first step of research was to prepare substrate from sago starch which was hydrolysed enzymatically using α- amylase and amyloglucosidase (AMG) enzymes. Preliminary research was conducted to determine optimum concentration in which S.cerevisiae var.ellipsoides can live and produce the highest ethanol content. The concentrations being tested were 18, 24, 30 and 36 % (g/L) of total sugar. The main research consists of two systems: batch and fed-batch. Result shows that 24 % concentration (g/L) was find to be the optimum consentration for S.cerevisiae var.ellipsoides with ethanol production reaches up to 10,2 ± 0,000 % (w/v). One of the main research is using batch cultivation. The best result of highest ethanol concent was reached (10,77 ± 0,000 % w/v) when aeration was stopped after biomass condition has reached the maximum condition. The best result on fed-batch cultivation with the highest ethanol concentration (12,05 ± 0,00 % w/v) also was gained at the same treatment with feed concentration of glucose 16 % g/L. Based on calculation of cultivation kinetic parameters, it is shown that in batch cultivation the highest Yp/s, Yp/x (0,15; 0,47; 4,48) was gained on the third treatment that is aeration stopped at 30th hour. On fed-batch cultivation, the highest Yp/s and Yp/x value (0,51 and 5,05) is shown on treatment of which aeration is stopped after 30th hour and feed concentration of 16 % g/L.
Keyword: 

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.
Keyword: 

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.
Keyword: