Judul: Kajian Penggunaan Selulosa Mikrobial Sebagai Bahan Baku Pembuatan kertas
Abstrak: Paper refers to thin mass of felted sheet separated from water suspension of prevalently cellulose-based pulp fiber on a fine screen, followed by sheet forming, compression, drying and finishing action. Paper and paper products are widely used as printing and writing media, packaging material and other varieties of functions. World consumption of paper steadily increases at 3,05 % per year, while in Indonesia the yearly consumption in the last five years (i.e 2002 – 2006) recorded an average increase at 2,8%. Consequently, this calls for intensive use of cellulose-based materials. In general, the raw material for pulp and paper comes from woods, due to their more secured continuity-supply and favorable properties or characteristic. Conversely, this situation can enchanc the rate of forest destruction (deforestation) from which the woods are obtained. Nowadays, deforestation rate tends to increase uncontrollably along with increasing-demand for woods and their derived products, including pulp and paper. Such alarming deforestation can exert negative impacts on the environment, among which is global warming. The global warming further will affect climate change radically and natural disasters (e.g. floods, erosion, storms, and hurricanes). The use of wood for pulp, paper, and other celullose based products reveals several weaknesses, among others, high energy consumption and catastrophic environmental pollution caused by the use of chemical substances for the delignification (lignin dissolution) process during wood pulping, which harmful to human beings and other living creatures. Another set back is the low productivity of wood for the supply of cellulose (i.e. polymer containing glucose units) compared to the cutting rotation of the tree growth to provide wood, which takes a long time and bring about concerns related to environmental issues. This unfavorable situation demand the seeking of other cellulose alternatives, which can expectedly substitute for or lessen the reliance on wood materials for pulp and paper manufacturing. One of the favorable alternatives is the microbial cellulose synthesized biologically from particular biomass materials potential as glucose source, using particular types of microorganisms (i.e. bacteria) among other Acetobacter species. The microbial cellulose afford remarkable advantage over the conventional wood derived sellulose, such as high level purity (free from lignin and hemicellulose), the easy isolation of the process, and exerting high cellulose crystallinity as well as its productivity. This entails an immense potency of raw material for microbial cellulose in an attempt to overcome the difficulty in procuring the conventional wood based cellulose materials for pulp and paper.
Keyword: 

Judul: Penggunaan Selulosa TandanKosong Kelapa Sawit dan Selulosa Mikrobial dari Nata de Cassavasebagai Pensubstitusi Selulosa Kayu dalam Pembuatan Kertas
Abstrak: Nowadays, forest-extracted wood cellulose still predominantly serves as raw material for pulp and paper manufacture in Indonesia. Consequently, the deforestation rate has alarmingly increased 2% per year. Attempts are necessary to seek alternative cellulose sources that sound potentially available, among which are empty oil-palm fruit bunches (EOPFB) and microbial-cellulose, as synthesizedwith the aid of microorganisms from substrate containing glucose, fructose, sucrose, or other simple carbohydrates, such as juicy waste from tapioca processing (e.g. nata de cassava). In this research, pulp of nata de cassava‟s microbial cellulose was mixed with EOPFB pulp at various proportions (w/w), i.e. 100%+0%, 75%+25%, 50%+50%, 25%+75%, 0%+100%to be processed into pulp and paper. Grammage target made was 60 gr/m2 and 120 gr/m2. Prior to paper-sheet forming, additives were added to such mixture (i.e. 2% alum, 2.5% tapioca starch, and 5% kaolin). Sheet forming also made without additives (as control). The forming of each combination between mixture proportion, grammage target and additive/control-use was replicated 2 times, and the data examined comprised pulp/paper physical and strength properties. The data were analyzed using a completely randomized design with factorial pattern. The yields of microbial-cellulose pulp and of EOPFB pulp were consecutively (wet basis) 60,09% and 61,619%. Physical and strength properties of paper with grammage 60 gr/m2and 120gr/m2consecutively, i.e. water content (4,04-8,95% & 3,83- 9,01%), grammage (59,8-78,92gr/m2& 107,64-145,32 gr/m2), tensile index 0,0056-0,0424 & 0,01002-0.06499 kNm/g), tear index (4,04-8,22 & 4,55-7,72 mN m2/gr),folding endurance (3,5-108,5 & 4-397,5), Cobb60 (56,86-211,32 & 75,03- 398,12 g/m2 for the smooth surface; and 51,07-218,91 & 57,65-404,46 g/m2for the rough/lower surface), brightness (15,64-38,03% & 13,1-26,26%) and printing opacity (62,81-97,55% & 42,99-99,38%). Analysis on biomass conversion revealed that the manufacture of paper from the mixture (w/w) of nata de cassava‟s microbial cellulose (50%) and empty oil palm fruit bunch pulp (50%) through the expansion of each cultivating areas, both totaling 200 ha can substitute for 4.247.156forest-tree stands per year. With this tree-saving figure, it can afford the CO2absorption (uptake) from the air equal to approximately 594.601,85 tons of CO2 per year.
Keyword: carbon uptake, biomass conversion analysis, pulp/paper, empty oil-palm fruit bunch, nata de cassava, microbial cellulose

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model