Judul: Biomassa Dan Polisakarida Mikroalga Porphyridium Cruentum Yang Dipanen Dengan Metode Berbeda Serta Inhibisi Α-Glukosidase
Abstrak: Polisakarida dan biomassa Porphyridium cruentum diketahui memiliki aktivitas dalam menghambat α-glukosidase. Kendala yang dihadapi dalam pengembangan P. cruentum ialah proses pemanenan. Proses pemanenan dalam penelitian ini dilakukan menggunakan metode sentrifugasi, gabungan mikrofiltrasi dan sentrifugasi serta gabungan sedimentasi dan sentrifugasi. Jumlah biomassa kering dari metode sentrifugasi, gabungan mikrofiltrasi dan sentrifugasi serta gabungan sedimentasi dan sentrifugasi berturut-turut 0,37 ± 0,01 g/L, 0,58 ± 0,12 g/L, dan 2,53 ± 0,32 g/L dengan nilai IC50 inhibisi α-glukosidase dari masing-masing ekstrak 209,67 ppm, 98,35 ppm dan 39,52 ppm. Jumlah polisakarida kering dari metode sentrifugasi, mikrofiltrasi (permeat), gabungan mikrofiltrasi dan sentrifugasi, serta gabungan sedimentasi dan sentrifugasi berturut-turut 3,44 ± 0,11 g/L, 1,36 ± 0,08 g/L, 1,72 ± 0,12 g/L, dan 2,38 ± 0,85 g/L dengan nilai IC50 inhibisi α-glukosidase dari masing-masing metode 432,17 ppm, 404,58 ppm, 267,68 ppm dan 246,39 ppm.
Keyword: biomassa, inhibisi α-glukosidase, pemanenan, polisakarida, Porphyridium cruentum

Judul: Pemisahan Biomassa Dan Eksopolisakarida Porphyridium Cruentum Menggunakan Ultrafiltrasi Serta Pengaruhnya Terhadap Aktivitas Inhibisi Α-Glukosidase
Abstrak: Porphyridium cruentum merupakan mikroalga merah uniseluler yang menyekresikan eksopolisakarida (EPS) ke dalam medium kultivasi. Biomassa dan EPS P. cruentum memiliki potensi untuk dikembangkan dalam bidang farmasi, nutraseutika, serta kosmeseutika. Konsentrasi garam tinggi dan volume air yang besar pada media kultivasi menyebabkan biaya produksi tinggi pada pemanenan dan pemisahan EPS. Penelitian ini bertujuan untuk menentukan pengaruh membran ultrafiltrasi (UF) terhadap karakteristik permeat (viskositas, pH, salinitas), kadar abu dan kadar garam EPS, serta aktivitas inhibisi α-glukosidase pada pemanenan dan pemisahan EPS. Penelitian yang dilakukan yaitu pengujian kandungan logam berat pada air laut, kultivasi mikroalga P. cruentum menggunakan media Guillard selama 40 hari, karakterisasi membran UF 0.05 dan 0.01 μm, pemanenan menggunakan UF 0.05 μm, pemisahan EPS menggunakan UF 0.01 μm, pengeringan biomassa dan EPS menggunakan freeze dryer. Kandungan logam berat (Hg, As, Cd, Cu, Pb, Zn, Ni) air laut yang digunakan masih berada dalam standar baku mutu untuk biota laut. Sel P. cruentum umur 40 hari berbentuk bulat, berwarna merah, dan diameternya 4.86-9.93 μm. Nilai OD, pH, salinitas, dan viskositas P. cruentum berturut-turut 0.83 ± 0.004, 7.64 ± 0.005, 47.23 ± 0.05‰, 7.97 ± 0.25 cp. Permeabilitas membran UF 0.05 μm (137.32 L/m2jam) lebih besar dibandingkan membran UF 0.01 μm (62.38 L/m2jam). Nilai fluks kultur yang dipanen menggunakan UF 0.05 μm mengalami penurunan dari 131.37 L/m2jam ke 94.75 L/m2jam dan rejeksi biomassa 96%. Membran UF 0.05 μm mampu menahan biomassa P. cruentum. Fraksi retentat 1 (R1) dan permeat 1 (P1) dihasilkan pada proses pemanenan. Fraksi retentat merupakan bagian yang tertahan di membran sedangkan permeat merupakan bagian yang lolos dari membran. Nilai fluks pada pemisahan EPS menggunakan UF 0.01 μm mengalami penurunan dari 58.11 L/m2jam ke 51.53 L/m2jam. Penurunan fluks menunjukkan fouling pada membran UF. Fraksi retentat 2 (R2) dan permeat 2 (P2) dihasilkan pada proses pemisahan EPS. Proses pemisahan EPS menyebabkan terjadinya penurunan viskositas, salinitas, berat kering, kadar abu, dan kadar garam dari P1 ke P2. Senyawa yang teridentifikasi menggunakan Fourier Transformed Infrared (FTIR) pada P1 dan P2 adalah simetrik COO dan C-O dengan COOH serta COOasam uronik. Eksopolisakarida P. cruentum mengandung maltoheptosa yang dapat berperan sebagai immunomodulator. Jumlah maltoheptosa yaitu P1 (12.42 g/L), R2 (14.19 g/L), dan P2 (16.11 g/L). Nilai Inhibition Concentration (IC50) inhibisi α-glukosidase P. cruentum yaitu P1 (419.06 μg/mL), R1 (425.48 μg/mL), P2 (178.67 μg/mL), dan R2 (502.25 μg/mL). Aktivitas inhibisi α-glukosidase terbaik pada P2 178.67 μg/mL. Penggunaan membran UF pada proses pemisahan EPS memengaruhi komposisi EPS sehingga juga berpengaruh terhadap aktivitas inhibisi α-glukosidase.
Keyword: eksopolisakarida, α-glukosidase, P. cruentum, ultrafiltrasi

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