Judul: Biosintesis Nanopartikel Perak Lactobacillus delbrueckii subsp. bulgaricus Sebagai Antifungi Pyricularia oryzae
Abstrak: Pyricularia oryzae adalah fungi patogen penyebab penyakit blas pada tanaman padi. Pengendalian P.oryzae dilakukan dengan nanopartikel perak yang telah dimanfaatkan di bidang pertanian, lingkungan, dan teknologi. Penelitian ini bertujuan melakukan biosintesis nanopartikel perak dari Lactobacillus delbrueckii subsp. bulgaricus yang akan dimanfaatkan sebagai agen antifungi P.oryzae. Nanopartikel perak disintesis dengan menggunakan metabolit sekunder dari L.delbrueckii subsp. bulgaricus yang mampu mereduksi perak nitrat (AgNO3) secara ekstraseluler dalam medium de Man Rogosa and Sharpe (MRS). Terbentuknya nanopartikel perak dalam larutan uji MRS diketahui menggunakan Spektrofotometer UV-Vis. Analisis ukuran partikel ditentukan menggunakan Particle Size Analyser (PSA). Aktivitas antifungi diuji menggunakan metode difusi. Pembentukan nanopartikel perak dari L.delbrueckii subsp. bulgaricus terdeteksi pada panjang gelombang 423 nm. Nanopartikel perak yang terbentuk rata-rata berukuran 2.0 nm dengan nilai Polydispersity Index (PI) 0,288. Aktivitas penghambatan P.oryzae tertinggi dari nanopartikel perak sebesar 24.33 mm pada konsentrasi 75%.
Keyword: antifungi, Lactobacillus delbrueckii sp, nanopartikel perak, perak nitrat, PSA

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.
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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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