Judul: Pengaruh Praperlakuan Alkali dan Asam terhadap Karakteristik Mutu Bakto Agar Gelidium sp.
Abstrak: Agar merupakan polisakarida yang ditemukan dalam dinding sel alga merah dan dimanfaatkan sebagai media pertumbuhan mikrobiologi. Rumput laut yang dapat dimanfaatkan sebagai bahan pembuatan agar media yaitu rumput laut Gelidium sp. Pemanfaatan Gelidium sp. masih terbatas karena metode ekstraksinya yang cukup sulit sehingga dibutuhkan suatu metode yang tepat untuk menghasilkan agar media dari Gelidium sp. Tujuan penelitian ini yaitu untuk mempelajari pengaruh praperlakuan NaOH dan asam asetat dengan konsentrasi berbeda terhadap mutu agar media Gelidium sp. serta membandingkannya dengan agar media komersial. Alkali yang digunakan adalah NaOH dengan konsentrasi 4%, 5%, dan 6%. Asam yang digunakan yaitu asam asetat dengan konsentrasi 0,5% dan 1%. Praperlakuan dengan konsentrasi NaOH 4% dan asam asetat 0,5 % masuk ke dalam standar mutu bakto agar grade reguler pada parameter kadar air dan kadar abu, serta grade premium pada parameter kadar abu tak larut asam dan kekuatan gel.
Keyword: asam asetat, agar media, ekstraksi agar, Gelidium sp., NaOH

Judul: Pengaruh Praperlakuan Alkali dan Bagian Talus Sargassum polycystum terhadap Karakteristik Asam Alginat
Abstrak: Asam alginat merupakan produk antara dalam proses ekstraksi alginat. Asam alginat pada penelitian ini dihasilkan dari tiga bagian talus yang berbeda. Metode yang digunakan yaitu ekstraksi asam alginat dengan pelarut Na2CO3 2%. Tahapan praperlakuan dilakukan sebelum proses ekstraksi dengan cara perendaman menggunakan pelarut KOH untuk meningkatkan kualitas asam alginat. Penelitian bertujuan menentukan pengaruh praperlakuan alkali dan bagian talus S. polycystum terhadap karakteristik asam alginat serta membandingkan dengan standar mutu alginat. Praperlakuan alkali dan bagian talus memberi pengaruh nyata terhadap rendemen, viskositas, dan kekuatan gel asam alginat. Karakteristik asam alginat terpilih yaitu pada faktor praperlakuan KOH 0.9% dengan talus bagian pangkal yang memiliki rendemen sebesar 21.51%, kadar abu 10.34%, kadar air 7.04%, nilai pH 2.54, viskositas 53.37 cP, derajat putih 57.91%, dan kekuatan gel 58.80 g/cm2. Karakteristik asam alginat yang dihasilkan telah memenuhi standar asam alginat yang ditetapkan oleh Food and Agricultural Organization, kecuali pada parameter kadar abu.
Keyword: asam alginat, bagian talus, KOH, Sargassum polycystum

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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