Judul: Ekstraksi senyawa antibakteri dari diatom laut Nitzschia sp. dan uji aktivitasnya terhadap bakteri gram positif dan negatif
Abstrak: Mikroalga merupakan mikroorganisme yang sangat besar jumlahnya, namun haru sedikit yang telah diteliti secara mendalam mengenai senyawa bioaktif dihasilkan. Salah satu senyawa bioaktif yang dihasilkan mikroalga adalah senyawa yan! antibiotik. Jenis mikroalga yang telah diteliti diantaranya adalah dari kelas Bacillariophyta atau diatom, yaitu diatom Nitzschia. Penelitian terhadap diatom Nitzschia sp dilakukan oleh Duff (1966) (yang dikutip Metting dan Pyne, 1986), juga Nitzschia palatea yang diteliti oleh Chesters beserta Scott (1955) (yang dikutip Zajic, 1970), dan Nitzschia ovalis yang diteliti oleh Maksimova, et al. (1984) (yang dikutip De La Noue dan De Pauw, 1988). Hasil penelitian tersebut membuktikan bahwa diatom Nitzschia memiliki aktivitas antibakteri. Penelitian ini bertujuan untuk menentukan kurva pertumbuhan Nitzschia mengekstrak senyawa antibakteri pada setiap fase pertumbuhan, dan menguji aktivitas senyawa tersebut pada bakteri Gram positif Staphylococcus aureus dan Bacillus subtilis, serta bakteri Gram negatif Pseudomonas sp dan Escherichia coli. Kultur Nitzschia sp ditumbuhkan dalam F medium, dengan kepadatan awal 1,48 x 10' sel per ml medium, dan dikultivasi pada suhu ruang dengan diberi aerasi melalui selang silikon. Kultur diberi cahaya dari lampu TL 20 Watt dengan intensitas cahaya 2000 luks. ...
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Judul: Ekstraksi dan uji aktivitas senyawa antibakteri dari mikroalga chlorella sp
Abstrak: Mikroalga adalah mata rantai awal dalam suatu ekosistem perairan yang menghasilkan energi. Di Indonesia, mikroalga jenis Chiarella sp telah dibudidayakan tetapi secara umum, pemanfatannya masih terbatas di bidang akuakultur yaitu sebagai pakan alami seperti pakan larva udang, moluska dan zooplankton air tawar seperti rotifer, copepoda dan artemia. Selain sebagai pakan alami, Chiarella sp juga menghasilkan komponen bioaktif yang dapat berupa antibiotik, algisidal, toksin, bahan aktif untuk industri farmasi dan pemacu pertumbuhan (Pyne and Meeting, 1986). Ekstrak sel dan ekstrak media tumbuh Chiarella vulgaris dilaporkan memberikan aktivitas antibakteri pada bakteri gram positif dan bakteri gram negatif (Aubert, Aubert and Gauthier, 1979; Reichelt and Borowitzka, 1984 yang dikutip Pyne and Meeting, 1986). Penelitian ini bertujuan untuk menentukan kurva pertumbuhan Chiarella sp, mengekstrak senyawa antibakteri pada tiap fase pertumbuhan dan menguji aktivitasnya pada bakteri gram positif dan bakteri gram negatif. Mikroalga yang digunakan adalah Chiarella sp. Penelitian yang dilakukan meliputi tahap kultivasi Chiarella sp, ekstraksi dan uji aktivitas senyawa antibakteri yang dihasilkan terhadap bakteri gram positif Staphylococcus aureus dan Bacillus subtilis serta bakteri gram negatif Escherichia coli dan Pseudomonas sp.
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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