Judul: Pemurnian agar-agar dengan metode absorbsi kitosan
Abstrak: Alga yang biasanya disebut rumput laut merupakan salah satu komoditas perairan yang sangat mungkin dikembangkan di Indonesia. Agar-agar merupakan ekstrak kering polisakarida dari alga atau ganggang merah (Rhodophyceae). Agar-agar yang digunakan sebagai bahan pengental dalam bidang mikrobiologi biasa disebut agar media. Agar bakto banyak digunakan sebagai media kultur karena sifatnya yang lebih murni dibandingkan agar biasa. Namun pada uummnya, harga agar bakto di pasaran cukup mahal.
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Judul: Pemanfaatan Rumput Laut Gracilaria verrucosa Sebagai Produk Bakto Agar dan Aplikasinya Dalam Media Pertumbuhan Mikroorganisme
Abstrak: Gracilaria verrucosa is a kind of seaweed cultivated in brackish water with water salinity of 6-14 ppt. Gracilaria produces a primary compound hydrocoloid metabolite called agarophyt. The aim of this study was to utilize Gracilaria as a bacto agar product with three methods of drying and also to apply bacto agar as a gelling agent in the microbial growth media. The source of Gracilaria sp used in this study was a seaweed that is cultivated by farmers in the village of Langen Sari, Subang. Characterization of raw materials included analysis of moisture content, ash content, protein content, fat content, and carbohydrate content. Acid treatment was carried out before the extraction processing which the acid treatment used of 1% CH3COOH. Temperature and extraction time constant were used at a temperature of 90oC for 45 minutes. Drying methods were done with three, oven dryer, spray dryer, and drum drier. The application of bacto agar as microbial growth media was applying the product by growing yeast and bacteria. Nutrient Agar has been used as a media for the growth of bacteria and Potato Dextrose Agar has been used as a media for the growth of yeast. The inoculation of microbial cultures performed in the plate agar media. In the plate agar media, syneresis occurred when the incubation was accomplished for 48 hours. Therefore additional tests were performed to determine the concentration of the bacto agar to reduce syneresis by testing the addition of gel strength with bacto concentration to 1.5%, 2%, and 2.5%.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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