Judul: Ekstraksi senyawa antibakteri alga laut jenis Laurencia sp. yang berasal dari perairan kepulauan Seribu
Abstrak: Penelitian ini bertujuan untuk mengekstrak senyawa antibakteri dari alga laut spesies Laurencia (Klas Rhodophyceae), membandingkan jenis pela- rut yang digunakan dalam ekstraksi, mempelajari efektifitas bahan antibakteri terhadap pertumbuhan bakteri yang diujikan. Metode penelitian dibagi dalam dua tahap, yaitu ekstraksi zat antibak- teri dari Laurencia sp 1 dan Laurencia sp 2 serta pengujian kepekaan bahan antibakteri terhadap Staphylococcus aureus, Pseudomonas aeruginosa, Bacil- lus subtilis dan Escherichia coli dengan menggunakan modifikasi prosedur umum "Calibrated Dichotomous Sensitivity" (CDS) test. Ekstraksi yang di- lakukan merupakan tahap awal untuk mendapatkan ekstrak kasar ("crude ex- tract"). Pelarut organik yang digunakan adalah etanol absolut dan metanol 80%. Hasil ekstraksi Laurencia sp 1 yang menggunakan pelarut etanol abso- lut menunjukkan adanya aktifitas antibakteri terhadap Staphylococcus aureus dengan diameter penghambatan sebesar 11 mm (pada pengenceran 1:10) dan sebesar 13 mm (pada pengenceran 1:100 000); terhadap Bacillus subti- lis dengan diameter penghambatan sebesar 13 mm (pada pengenceran 1:100 000), sedangkan pada pengenceran 1:10 daerah penghambatannya negatif. S. aureus dikategorikan "sensitif" terhadap bahan antibakteri yang diekstrak dari Laurencia sp 1 dengan pelarut etanol absolut, sedangkan B. subtilis dikategorikan "resisten" terhadap bahan antibakteri tersebut. ...
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Judul: Ekstraksi antioksidan dari alga laut Laurencia sp. dan efektivitasnya dalam menghambat kerusakan awal minyak ikan
Abstrak: Perubahan pola konsumsi masyarakat menimbulkan sikap selektif masyarakat dalam memilih makanan yang bermutu baik. Hal tersebut akan memacu penggunaan zat- zat aditif yang dinilai dapat memperbaiki mutu makanan, seperti antioksidan. Antioksidan merupakan zat aditif yang berfungsi menghambat dan mencegah kerusakan minyak, lemak dan bahan pangan berlemak akibat proses oksidasi. Proses oksidasi ini menyebabkan ketengikan, menurunnya nilai gizi pangan dan dapat menim- bulkan senyawa toksik. Penelitian ini bertujuan untuk mempelajari efektivitas ekstrak antioksidan yang dihasilkan dari alga laut Laurencia sp. dalam menghambat kerusakan awal minyak ikan selama penyimpanan. Penelitian dibagi atas penelitian pendahuluan dan penelitian utama. Penelitian pen- dahuluan meliputi ekstraksi alga laut Laurencia sp. dalam keadaan segar dan dikeringkan serta melakukan pengujian aktivitas antioksidan. Ekstraksi yang dilakukan menggunakan pelarut metanol, dietil eter dan n-heksana secara berkesinambungan, dan uji aktivitas antioksidan menggunakan metode tiosianat. ...
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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