Judul: Studi Pengaruh Alkaline Pretreatment terhadap Delignifikasi pada Lignoselulosa Gracilaria sp. (Below Standard).
Abstrak: Gracilaria sp. (below standard) merupakan biomassa berlignoselulosa yang mengandung selulosa, hemiselulosa dan lignin. Kandungan lignin menghambat konversi selulosa menjadi gula sederhana. Delignifikasi merupakan suatu proses penghilangan lignin pada material berlignoselulosa. Delignifikasi yang dilakukan pada penelitian ini yaitu mengunakan alkaline pretreatment dengan variasi konsentrasi NaOH 0, 0,01 M dan 0,05 M pada suhu 27 oC serta waktu pretreatment selama 24 jam. Komposisi lignoselulosa dari rumput laut Gracilaria sp. (below standard) sebelum pretreatment memiliki selulosa, hemiselulosa dan lignin berturut-turut 10,88%, 9,85% dan 8,76%. Pretreatment yang dilakukan pada rumput laut Gracilaria sp. (below standard) memberi pengaruh terhadap kandungan hemiselulosa, lignin dan yield regenerated biomass. Penurunan bobot lignin tertinggi (63,22%) dan jumlah yield regenerated biomass terendah 62,9% dihasikan pada perlakuan konsentrasi NaOH 0,05 M. Mikrostruktur Gracilaria sp. (below standard) setelah pretreatment mengalami kerusakan berupa jaringan yang terkoyak dan tidak kompak. Filtrat yang pada perlakuan konsentrasi NaOH 0,05 M menghasilkan gula pereduksi sebesar 98,97%
Keyword: Alkaline pretreatment, Gracilaria sp. (below standard), lignoselulosa, NaOH

Judul: Ultrasonic Pretreatment of Gracilaria sp. Processing in  Bioethanol Manufacturing
Abstrak: Bioetanol terbuat dari bahan berselulosa melalui beberapa tahapan proses. Rumput laut Gracilaria sp. memiliki potensi sebagai bahan baku bioetanol karena mengandung selulosa. Praperlakuan ultrasonikasi dengan larutan alkali dalam pembuatan bioetanol menarik untuk dilakukan karena mampu meningkatkan rendemen etanol. Penelitian ini bertujuan untuk menentukan pengaruh waktu praperlakuan ultrasonikasi dengan larutan alkali pada bahan baku untuk meningkatkan kandungan total gula pereduksi dan kadar etanol. Tahapan penelitian meliputi persiapan sampel, praperlakuan ultrasonikasi dalam alkali dengan waktu 60, 90 dan 120 menit, sakarifikasi, fermentasi dan destilasi. Selulosa teridentifikasi pada sampel ditandai dengan adanya puncak pada bilangan gelombang 1058 cm-1 . Praperlakuan ultrasonikasi 120 menit menghasilkan kandungan total gula pereduksi dan kadar etanol tertinggi masing-masing sebesar 96,34 mg/mL dan 3%., Bioethanol is made from cellulosic materials through several stages of the process. Seaweed of Gracilaria sp. has potential as raw material for bioethanol since it contains high cellulose. The pretreatment of ultrasonication with alkaline solutions in bioethanol production is interesting because it can increase the yield of ethanol. This study aims to determine the effect pretreatment time of ultrasonication with alkaline solutions in increasing the total content of reducing sugars and ethanol yield. The research includes sample preparation, pretreatment of ultrasonication in alkaline at times 60, 90 and 120 min, saccharification, fermentation and distillation. Cellulose is identified in the functional group analysis characterized by a peak at wave number 1058 cm-1 . The pretreatment of 120 min ultrasonication resulted in the highest total content of reducing sugar and ethanol content of 96.34 mg/mL and 3% respectively.
Keyword: alkaline, bioethanol, Gracilaria sp, ultrasonication

Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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