Judul: Hidrogel Antibakteri Berbasis Polivinil Alkohol- Karaginan-AgNO3.
Abstrak: Hidrogel adalah salah satu polimer hidrofilik yang memiliki jaringan taut silang dan kemampuan mengembang dalam air. Hidrogel dapat dibuat dengan campuran polivinil alkohol (PVA), karaginan, dan zat antibakteri AgNO3. Penelitian ini bertujuan menyintesis hidrogel antibakteri berbasis PVA-karaginan- AgNO3, serta menentukan pengaruh komposisi, mempelajari karakterisasi dan potensinya sebagai zat antibakteri. Hidrogel PVA-karaginan-AgNO3 dipreparasi dengan kombinasi metode freeze-thaw dan iradiasi. Komposisi terbaik karaginan dan AgNO3 yang diperoleh dengan membuat hidrogel dari karaginan komersial, yaitu 3% karaginan dan 5 mM AgNO3. Hidrogel dengan komposisi terbaik memiliki kemampuan mengembang paling tinggi diantara komposisi yang lain. Analisis gugus fungsi karaginan hasil ekstraksi menunjukkan karaginan jenis kappa yang memiliki kadar air, viskositas, kadar sulfat, dan rendemen berturutturut sebesar 13%, 214 cPs, 9%, dan 44 %. Uji aktivitas antibakteri terbaik ialah hidrogel dengan AgNO3 5 mM. Hidrogel PVA-karaginan-AgNO3 memiliki potensi sebagai penutup luka dengan menunjukkan aktivitas antibakteri.
Keyword: antibakteri, hidrogel, karaginan, PVA-karaginan-AgNO3

Judul: Hidrogel Antibakteri Berbasis Polvinil Alkohol-Karaginan-ZnO.
Abstrak: Hidrogel merupakan kelompok yang terdiri atas material polimer yang mampu menyerap air dalam jaringan 3 dimensinya dan berpotensi sebagai penutup luka. Pada penelitian ini, hidrogel dibuat dengan mengombinasikan polimer sintetis polivinil alkohol (PVA), polimer alami karaginan, serta zat antibakteri ZnO menggunakan metode beku-leleh dan iradiasi gamma. Penelitian ini bertujuan menyintesis hidrogel PVA-karaginan-ZnO dari karaginan komersial dan hasil ekstraksi, serta menentukan pengaruh komposisi, karakterisasi hidrogel dan aktivitas antibakterinya. Komposisi terbaik dari PVA dan karaginan dalam sintesis hidrogel ialah 10%:3% karena memiliki kemampuan mengembang yang tinggi. Karaginan yang diekstraksi dari rumput laut Eucheuma cottonii merupakan jenis kappa-karaginan yang memiliki kadar air, rendemen, viskositas, dan kadar sulfat berturut-turut sebesar 13%, 44%, 214 cps, dan 9%, serta analisis FTIR pada 845 cm-1 (ikatan C-O-SO3 dari galaktosa-4-sulfat). Hidrogel PVA-karaginan-ZnO dari karaginan komersial maupun karaginan hasil ekstraksi dengan konsentrasi ZnO sebesar 0.5% atau 5000 ppm memiliki aktivitas antibakteri terbaik terhadap bakteri Staphylococcus aureus dan Escherichia coli. Hidrogel dari kombinasi PVA-karaginan-ZnO ini dapat dimanfaatkan sebagai penutup luka.
Keyword: hidrogel, karaginan, kemampuan mengembang, penutup luka

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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