Judul: Ekstraksi dan isolasi zat aktif dari mikroalga Scenedesmus acuminatus dan pengaruhnya terhadap pertumbuhan bakteri dan khamir
Abstrak: Mikroalga sebagai salah satu komoditi perikanan memiliki potensi yang besar untuk dimanfaatkan. Bebera- pa mikroalga telah diketahui dapat menghasilkan berbagai bahan bioaktif. Sebagai sumber bahan kimia mikroalga dapat mengha- silkan produk seperti gliserol, beta karotin, vitamin dan bahan-bahan bioaktif. Bahan bioaktif yang telah diketahui dapat dihasilkan dari mikroalga yaitu: anti oksidan, algicides, toksin, bahan obat-obatan dan zat pengatur pertumbuhan. Zat pengatur pertumbuhan merupa- kan zat aktif yang menarik perhatian para peneliti karena aktifitasnya yang bersifat memacu pertumbuhan. Mikroalga mengandung vitamin-vitamin yang terbagi menjadi dua kelompok yaitu kelompok vitamin yang terda- pat dalam sel (vitamin content) dan kelompok vitamin yang diekskresikan oleh sel mikroalga ke dalam media pertumbuhannya (excreted vitamin). Vitamin termasuk dalam kelompok faktor pertumbuhan yang dapat berpengaruh terhadap pertumbuhan mikroorganisme. Tujuan penelitian ini adalah untuk mengekstraksi zat aktif dari mikroalga Scenedesmus acuminatus dan mempelajari pengaruhnya ...
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Judul: Pemisahan Ekstrak lntraseluler dari Mikroalga  Nitzschia closterium dan Penentuan Konsentrasi Hambatan Minimumnya Terhadap Mikroba Patogen
Abstrak: Mikroalga merupakan salah satu biota perairan yang belum banyak dimanfaatkan secara optimal. Di Indonesia, pemanfaatan biota ini hanya terbatas sebagai pakan alami. Selain sebagai pakan, mikroalga merupakan salah satu sumber bahan aktif dan bahan kimia yang sangat potensial. Sejumlah peneliti menyatakan pendapatnya secara pasti bahwa beberapa spesies mikroalga menghasilkan metabolit intraseluler dan ekstraseluler yang dapat menghambat pertumbuhan organisme lain. Selain vitamin, asam amino, karbohidrat dan nutrien lainnya, mikroalga juga mengandung komponen aktif biologi yang didalamnya juga termasuk antibiotik, algasidal, racun, komponen aktif farmasi (antitumor, antikanker) dan komponen pemacu pertumbuhan.
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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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