Judul: Optimasi Biosintesis Nanopartikel Perak oleh Lactobacillus delbrueckii subsp.bulgaricus
Abstrak: Nanopartikel perak banyak dimanfaatkan di bidang kesehatan dan industri, misalnya sebagai antibakteri, antifungi, antivirus, antiinflamasi, deteksi apoptosis dan terapi kanker. Biosintesis nanopartikel perak dengan menggunakan mikroorganisme mulai dikembangkan karena bersifat ramah lingkungan, non toksik, murah, dan mudah. Kontrol distribusi ukuran partikel selama sintesis merupakan kriteria yang penting dalam biosintesis nanopartikel perak. Penelitian ini bertujuan untuk melakukan optimasi biosintesis nanopartikel perak dengan variasi waktu inkubasi kultur, suhu reaksi biosintesis nanopartikel perak dan pH. Lactobacillus delbrueckii subsp.bulgaricus ditumbuhkan pada media Mann Rogose and Sharp cair pada suhu 42 oC dan agitasi 150 rpm dengan variasi waktu inkubasi 12, 24, 36, 48, 60, dan 72 jam. Optimasi suhu reaksi dilakukan dengan menggunakan variasi suhu 28, 40, 50 dan 60 oC. Optimasi pH dilakukan dengan menggunakan variasi pH 4.0, 5.0, 6.0, 7.0 dan 8.0. Hasil yang diperoleh menunjukkan bahwa tidak ada pengaruh perbedaan lama inkubasi bakteri terhadap biosintesis nanopartikel perak. Optimasi biosintesis nanopartikel perak diperoleh pada suhu reaksi 60 oC dengan ukuran nanopartikel perak 2.1 nm dan pH 8.0 dengan ukuran nanopartikel perak 8.3 nm.
Keyword: 

Judul: Pemanfaatan Metabolit Ekstraseluler Lactobacillus delbrueckii Subsp. bulgaricus dalam Pembentukan Nanopartikel Perak
Abstrak: The Synthesis of silver nanoparticles using microorganisms as well as metabolites have been developed with consideration of the hazardous waste free environment. The objective of this research was to biosynthesis the silver nanoparticles with the extracellular metabolites of L. delbrueckii subsp. bulgaricus. Silver nitrate (AgNO3) being reduced on the extracellular level with help of de Man, Rogosa and Sharpe (MRS) medium which contained with metabolism compound product of L. delbrueckii subsp. bulgaricus which then formed the silver nanoparticles as a metal. The existence of silver nanoparticles inside the MRS medium was detected by UV-Vis that based on specific absorption spectrum of silver nanoparticles on the 400 nm wavelength. The Analysis of Fourier Transform Infrared (FTIR) showed that there were organic components that plays role in the silver nanoparticles formation. The protein reductor of AgNO3 ions was presumed to be the organic component that contained in the metabolites of L. delbrueckii subsp. bulgaricus and plays role in the formation of silver nanoparticles. Furthermore, particle size analysis provides the information about the average size of the formed silver nanoparticles, that was equal to 2.7 nm
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: