Judul: Uji Aktivitas Antibakteri dari Mikroalga Chlorella sp.
Abstrak: Mikroalga Chlorella sp. Merupakan mikroalga uniselluler dan salah satu spesies mikroalga yang memiliki banyak manfaat. Mikroalga ini dapat menghilangkan atau menetralisir senyawa racun di dalam tubuh. Tujuan penelitian ini adalah menguji senyawa antibakteri dari mikroalga Chlorella sp. dengan metode maserasi dan dievaporasi. Ekstrak kasar yang diperoleh kemudian di uji kadar lemak dan uji antibakteri. Ekstrak mikroalga Chlorella sp. memiliki diameter zona hambat menggunakan pelarut metanol terhadap bakteri Pseudomonas sp. terbesar yaitu 4.4 mm. Diameter zona hambat dari ekstrak mikroalga Chlorella sp. menggunakan pelarut n-heksana terhadap bakteri E. coli terbesar yaitu 5 mm
Keyword: Mikroalga, Chlorella sp., Antibakteri, Metanol, N-heksan

Judul: Ekstraksi dan uji aktivitas senyawa antibakteri dari mikroalga chlorella sp
Abstrak: Mikroalga adalah mata rantai awal dalam suatu ekosistem perairan yang menghasilkan energi. Di Indonesia, mikroalga jenis Chiarella sp telah dibudidayakan tetapi secara umum, pemanfatannya masih terbatas di bidang akuakultur yaitu sebagai pakan alami seperti pakan larva udang, moluska dan zooplankton air tawar seperti rotifer, copepoda dan artemia. Selain sebagai pakan alami, Chiarella sp juga menghasilkan komponen bioaktif yang dapat berupa antibiotik, algisidal, toksin, bahan aktif untuk industri farmasi dan pemacu pertumbuhan (Pyne and Meeting, 1986). Ekstrak sel dan ekstrak media tumbuh Chiarella vulgaris dilaporkan memberikan aktivitas antibakteri pada bakteri gram positif dan bakteri gram negatif (Aubert, Aubert and Gauthier, 1979; Reichelt and Borowitzka, 1984 yang dikutip Pyne and Meeting, 1986). Penelitian ini bertujuan untuk menentukan kurva pertumbuhan Chiarella sp, mengekstrak senyawa antibakteri pada tiap fase pertumbuhan dan menguji aktivitasnya pada bakteri gram positif dan bakteri gram negatif. Mikroalga yang digunakan adalah Chiarella sp. Penelitian yang dilakukan meliputi tahap kultivasi Chiarella sp, ekstraksi dan uji aktivitas senyawa antibakteri yang dihasilkan terhadap bakteri gram positif Staphylococcus aureus dan Bacillus subtilis serta bakteri gram negatif Escherichia coli dan Pseudomonas sp.
Keyword: 

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: