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: 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: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite