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: Pengaruh meode ekstraksi terhadap jumlah ekstrak dan aktivitas senyawa abtibakteri dari mikroalga chlorella sp.
Abstrak: Mikroalga saat ini mendapat perhatian dari berbagai kalangan karena mampu memproduksi berbagai bahan kimia seperti protein, lipid, pigmen, serta berpotensi dalam menghasilkan asam-asam lemak tidak jenuh, asam-asam lemak essensial, antibiotik, vitamin, energi dan sebagai pakan ikan. Chlorella sp. merupakan salah satu spesies mikroalga yang memiliki banyak manfaat, telah diproduksi secara komersial dan digunakan sebagai makanan kesehatan (health food). Chlorella juga menghasilkan komponen bioaktif, diantaranya adalah senyawa antibakteri yang merupakan hasil metabolit sekunder. Senyawa antibakteri dari mikroalga Chlorella diperoleh dengan cara ekstraksi. Penelitian ini dilakukan dalam dua tahap, yaitu penelitian pendahuluan dan penelitian utama. Penelitian pendahuluan bertujuan untuk menentukan kurva pertumbuhan Chlorella pada medium PHM (Phosfat Hidrogen Magnesium) yang disimpan di ruang AC (suhu 18°C 20°C) serta menentukan umur panen. Penentuan kurva pertumbuhan dilakukan dengan cara menghitung jumlah sel setiap hari. Penghitungan jumlah sel dengan menggunakan hemasitometer sampai kultur mengalami fase kematian. Sedangkan penelitian utama bertujuan untuk mempelajari metode ekstraksi dengan waktu pengadukan yang berbeda-beda dan ekstraksi secara bertahap. Selain itu penelitian utama bertujuan untuk menguji aktivitas dari senyawa antibakteri Chlorella sp. terhadap pertumbuhan bakteri Pseudomonas sp. dan Staphylococcus aureus. Ekstraksi biomassa dari mikroalga Chlorella sp. dilakukan dengan pengadukan selama 6 jam, 12 jam dan 18 jam menggunakan modifikasi metode Quinn. Sedangkan pengujian aktivitas senyawa antibakteri dilakukan dengan menggunakan metode CDS (Calibrated Dichotomous Sensitivity) test. Dari penelitian.pendahuluan diperoleh hasil bahwa umur kultur Chlorella sp. mencapai 85 hari serta terdiri dari 5 fase pertumbuhan yaitu fase lag, fase log (1-18 hari), fase penurunan laju pertumbuhan (19-22 hari), fase stasioner (23-71 hari), serta fase kematian (72 hari). Umur panen ditentukan pada saat kultur berada pada fase tengah stasioner (47 hari). ...
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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