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: Sintesis Nanofiber dari Polivinil Alkohol (PVA)-Kolagen Menggunakan Metode Elektrospining.
Abstrak: Salah satu penggunaan polimer polivinil alkohol (PVA) yaitu sebagai matriks yang akan dicampurkan kolagen dalam pembuatan bahan pembalut luka primer yang berfungsi menutup luka, menghambat pertumbuhan bakteri dan media pembentukan jaringan. Penambahan PVA agar mendapatkan serat dengan sifat mekanik yang lebih baik. Serat PVA-kolagen dari campuran larutan PVA (10%) dan variasi konsentrasi kolagen (1% dan 2%) dibuat menggunakan metode electrospinning dengan pengaruh variasi tegangan 15 kV, 19 kV, dan 23 kV. Analisis gugus fungsi menunjukkan adanya senyawa identik yang dihasilkan dan tidak terbentuk gugus fungsi baru. Analisis XRD menunjukkan pelebaran puncak kristal dan menurunkan intensitas puncak kritalin. Data SEM menunjukkan adanya pengaruh variasi tegangan dan konsentrasi kolagen terhadap morfologi serat. Serat PVA-kolagen 2% menghasilkan serat yang lebih seragam, berdiameter 284-426 nm, memiliki ketebalan 0.0324-0.0483 mm, dan memiliki persen elongasi yang tinggi sehingga dapat digunakan sebagai bahan pembalut luka.
Keyword: electrospinning, kolagen, polivinil alkohol

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.
Keyword: