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: Pengaruh Pemanasan Microwave Terhadap Sifat Penerimaan Enzim Amilolitik dan Holoselulolitik Untuk Produksi Fermentable Sugar dari Empulur Sagu (Metroxylon sagu)
Abstrak: Sago (Metroxylon sagu) has been one of the important raw materials for the production of useful substances. Because contains more than 80% carbohydrates, which is consists of 55.86% starch and 14.52% lignocellulosic material, the utilization of sago pith is essential for the fermentable sugar production in terms bioenergy production. In other hand, using the sago pith might prevent the waste of the resources. Lignin is one of the main components in lignocellulosic materials in sago pith. Its existence influence the sago pith structural rigidity by holding and stiffening the fibres together so decreasing the enzymatic suspectibility of sago pith. The use of microwave radiation is a promising approach to pretreatment that utilizes thermal and non-thermal effects generated by microwaves in aqueous environments. This study have shown that the microwave heating caused the process of swelling and gelatinization of starch granules and also could enhance lignin degradation itself. Thus could be very efficient in destroying the starch and lignin crystalline arrangement, obtaining a soft gel, and destroying cellulose-hemicellulose structure. On the other hand, if the energy that given to the slurry of sago pith more than it needed then it would build resistant characteristic of sago pith and increasing enzymes concentration wouldn’t enhance yield of reducing sugars. Pretreatment were evaluated based on yields of total sugars, reducing sugars, polymerization degree, equivalent dextrose, filtrate volumes, weight of residue, and filtrate purity from enzymatic hydrolysis of the pretreated biomass. The experimental results in this study can be used in existing simultant process of bioethanol production by using Pichia stipitis and Saaccharomyces elippsoides. The highest ethanol content was given by technical glucose and fermented by Pichia stipitis, prove the pretreatment could not efficiently degradated biomass due to the lignin content was too high. Thus, the lignin content is one of the matter in efficiently pretreatment in order to get the highest yield of reducing sugars.
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Judul: Transisi Fasa Materi Hadronik ke Materi Kuark pada Inti Bintang Neutron.
Abstrak: Bintang neutron terdiri dari beberapa lapisan yang disusun oleh materi nuklir yang berbeda dengan kerapatan yang semakin tinggi ketika mendekati pusat bintang. Inti luar bintang neutron disusun oleh materi hadronik (nukleon, lepton, dan hyperon), sedangkan inti dalam bintang neutron disusun oleh kuark-kuark bebas (up, down, strange) yang saling berinteraksi. Tujuan penelitian ini adalah mempelajari bagaimana transisi dari inti luar ke inti dalam bintang neutron dengan menggunakan pendekatan RMF (Relativistic Mean Field) untuk materi hadronik dan CIDDM (Confined Isospin Density Dependent Mass) untuk materi kuark. Tekanan transisi diperoleh ketika potensial kimia barion materi hadronik dan materi kuark bernilai sama. Nilai tekanan transisi dengan parameter SU6-TM1 sekitar 87 MeV/fm3 dan diperoleh massa maksimum bintang neutron yaitu 1.92M dengan jari-jari sekitar 8.62 km. Nilai tekanan transisi dengan parameter SU6-G2 sekitar 53 MeV/fm3 dan massa maksimum bintang neutron yaitu 1.88M dengan jari-jari sekitar 8.16 km. Jenis transisi fasa adalah orde satu ditandai dengan diskontinuitas dalam kerapatan energi (adanya mixed phase). Parameter-parameter pada model nuklir yang digunakan menyebabkan perbedaan kekakuan persamaan keadaan (EOS) dari materi hadronik dan materi kuark sehingga nilai tekanan transisi dari fasa hadronik ke fasa kuark juga berbeda.
Keyword: bintang neutron, persamaan keadaan, transisi fasa