Judul: Sintesis Serat Nano dari Alginat-Polivinil Alkohol Menggunakan Metode Pemintalan Elektrik.
Abstrak: Alginat sudah dikenal sebagai polimer yang banyak digunakan untuk keperluan medis misalnya sebagai bahan pembalut luka. PVA merupakan polimer yang larut dalam air, memiliki kemampuan membentuk serat yang baik, dan biokompatibel. Serat alginat-PVA dibuat menggunakan metode pemintalan elektrik dengan campuran larutan Alginat (2%)/PVA (10%) dalam rasio volume 3/3, 2/3, dan 1/3 serta pengaruh jarak spinneret-kolektor 8 cm, 10 cm, dan 12 cm. Analisis gugus fungsi menunjukkan keidentikan senyawa yang dihasilkan dan tidak adanya pembentukan gugus fungsi baru. Analisis XRD menunjukkan perubahan puncak kristal yang semakin melebar dan menurunkan intensitas puncak kristalin. Data SEM menunjukkan pengaruh variasi komposisi alginat dan jarak spinneret-kolektor terhadap morfologi serat yang dihasilkan. Jarak spinneret-kolektor 10 cm menghasilkan serat yang kontinyu dan tidak mengalami pembengkokkan. Serat alginat-PVA 3/3 (v/v) dan 2/3 (v/v) memenuhi syarat perdagangan serat nano karena memiliki diameter serat sekitar 172.242 nm – 326.244 nm. Berdasarkan hasil nilai kuat tarik dan persen elongasi serat alginat-PVA 3/3 (v/v) dapat digunakan sebagai pembalut luka karena memenuhi standar material medis.
Keyword: alginat, pemintalan elektrik, polivinil alkohol

Judul: Hidrogel Antibakteri Berbasis Polivinil Alkohol- Alginat-ZnO.
Abstrak: Alginat diperoleh dari ekstraksi rumput laut Sargassum sp. Hidrogel berbasis polivinil alkohol-alginat berpotensi sebagai matriks untuk memperbaiki dan meregenerasi jaringan akibat luka. Hidrogel PVA-alginat ditambahkan ZnO sebagai antibakteri, dan disintesis dengan teknik kombinasi beku-leleh dan iradiasi gamma. Penelitian bertujuan menyintesis hidrogel PVA-alginat-ZnO dari alginat komersial untuk mendapatkan komposisi optimum, dilanjutkan sintesis hidrogel PVA-alginat-ZnO dari alginat ekstraksi dan menguji aktivitas antibakteri. Alginat hasil ekstraksi ditentukan kadar air, rendemen, viskositas, dan gugus fungsi. Kadar air yang diperoleh sebesar 14%, rendemen sebesar 34%, dan viskositas sebesar 12 cP. Keberhasilan sintesis hidrogel ditandai adanya gugus fungsi ester pada FTIR. Komposisi optimum hidrogel diperoleh berdasarkan nilai kemampuan mengembang dan aktivitas antibakterinya. Hidrogel alginat hasil ekstraksi memberikan nilai yang tidak jauh berbeda dibandingkan alginat komersial. Aktivitas antibakteri alginat hasil ekstraksi lebih baik dibandingkan alginat komersial. Morfologi hidrogel dilihat menggunakan mikroskop elektron payaran menunjukkan adanya pori-pori dan distribusi ZnO.
Keyword: alginat, antibakteri, hidrogel, matriks, PVA-alginat-ZnO

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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