Judul: Aktivitas Ekstrak Daun Cengkeh dalam Meregulasi Penuaan: Studi pada Schizosaccharomyces pombe
Abstrak: Radikal bebas merupakan penyebab penuaan (aging) dan menurunnya kemampuan hidup sel. Senyawa antioksidan seperti flavonoid banyak dimanfaatkan sebagai penangkal radikal bebas. Salah satu tanaman yang mengandung flavonoid ialah cengkeh. Informasi mengenai manfaat ekstrak daun cengkeh sebagai agen antioksidan dan antipenuaan belum banyak tersedia. Oleh karena itu, penelitian ini bertujuan untuk mengetahui kemampuan ekstrak daun cengkeh dalam meregulasi penuaan seluler. Pada penelitian ini digunakan khamir Schizosaccharomyces pombe yang umum digunakan sebagai organisme model untuk mempelajari siklus sel dan aging. Total rendemen yang dihasilkan dari ekstraksi daun cengkeh dengan metode maserasi menggunakan pelarut etanol 70% yaitu sebesar 12.9%. Konsentrasi ekstrak daun cengkeh (100 ppm) dapat memperpanjang masa hidup khamir dan meningkatkan resistensi khamir terhadap cekaman oksidatif (H2O2). Hal ini mengindikasikan bahwa ekstrak daun cengkeh memiliki potensi sebagai agen penunda penuaan dan antioksidan. Mekanisme toleransi terhadap cekaman oksidatif diketahui terlibat dalam proses penundaan penuaan yang diperantarai oleh aktivitas mitokondria. Pada penelitian ini, ekstrak daun cengkeh tidak meningkatkan aktivitas mitokondria sel khamir sehingga dapat diduga bahwa mekanisme antipenuaan dan antioksidan ekstrak daun cengkeh tidak terkait terhadap aktivitas mitokondria.
Keyword: aging, ekstrak daun cengkeh, Schizosaccharomyces pombe

Judul: Aktivitas Ekstrak Cengkeh Sebagai Agen Anti-aging pada Saccharomyces cerevisiae
Abstrak: Cengkeh (Syzygium aromaticum) merupakan salah satu tumbuhan Indonesia yang menghasilkan antioksidan. Hingga saat ini, aktivitas cengkeh sebagai zat antioksidan dan potensinya sebagai senyawa anti-penuaan (antiaging) in vivo belum pernah dilaporkan. Saccharomyces cerevisiae merupakan khamir yang banyak dijadikan sebagai model untuk mengetahui biologi molekular dan biokimia pada level seluler. Oleh karena itu, penelitian ini bertujuan mengetahui pengaruh ekstrak cengkeh terhadap masa hidup S. cerevisiae. Bunga cengkeh diekstraksi menggunakan metode maserasi. Metode yang digunakan untuk analisis penuaan sel dan pengaruh ekstrak cengkeh pada viabilitas khamir terhadap cekaman oksidatif adalah metode spot test. Khamir diamati aktivitas mitokondrianya menggunakan mikroskop fluoresens. Ekstrak cengkeh diketahui mampu memperpanjang masa hidup khamir dan mampu meningkatkan toleransi khamir terhadap cekaman oksidatif. Kemampuan tersebut diduga melalui peningkatan aktivitas mitokondria khamir.
Keyword: Saccharomyces cerevisiae, metode spot test, zat antioksidan

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