Judul: Kajian Produksi Sel Khamir (Saccharomyces cerevisiae) Melalui Kultivasi Semi Sinambung (Fed-Batch).
Abstrak: Saccharomyces merupakan genus khamir yang memiliki kemampuan mengubah glukosa menjadi sel, etanol dan dan CO2. Industri fermentasi khamir, umumnya menggunakan kultivasi batch dimana proses yang digunakan lebih mudah tetapi tidak memberikan hasil yang tinggi dibandingkan dengan kultivasi fed-batch. Sistem fed-batch adalah suatu sistem yang menambahkan media baru secara teratur pada kultur tertutup, tanpa mengeluarkan kultur yang ada di dalam bioreaktor. Keuntungan menggunakan fed-batch secara teoritis adalah menghasilkan jumlah sel yang lebih tinggi. Tujuan dari penelitian ini adalah melihat pengaruh laju alir susbtrat pada sistem fed-batch terhadap jumlah biomassa, gula pereduksi dan pH, dan menentukan laju alir susbtrat terbaik untuk menghasilkan sel dan rendemen sel yang lebih tinggi. Penelitian dilakukan dengan sistem batch terlebih dahulu untuk melihat pola pertumbuhan Saccharomyces cerevisiae pada batch dan menentukan saat yang tepat untuk memulai fed-batch. Pada kultur batch diperoleh produksi biomassa sel tertingi pada fase stasioner sebesar 10,31 g/L pada jam ke 30, dan menghasilkan rendemen sel sebesar 0,04 g/g. Substrat saat sel tertinggi dan substrat terendah ini digunakan sebagai waktu untuk mengawali pengumpanan pada fed-batch. Laju alir yang dicobakan pada kultivasi fed-batch adalah F=0,12L/jam; F=0,18L/jam dan F=0,24L/jam. Pada kultivasi fed-batch diperoleh F=0,18/jam merupakan laju alir yang memberikan nilai produksi biomassa tertinggi sebesar 10,66 g/L dengan nilai produksi sel tiap jam sebesar 0,06 g/L/jam. Laju alir yang lebih rendah (F=0,12/jam) merupakan laju alir yang terbaik untuk menghasilkan nilai rendemen sel (Yx/s) tertinggi yaitu sebesar 0,07 g/g. Pada laju alir yang kecil, susbtrat yang ditambahkan dimanfaatkan Saccharomyces dalam memperbanyak sel, sedangkan pada laju alir substrat yang lebih besar, kelebihan suplai substrat digunakan untuk pembentukan etanol selain sel sehingga memperkecil nilai Yx/s.
Keyword: Batch, Fed-batch, laju alir, Saccharomyces cerevisiae

Judul: Rekayasa Bioproses Produksi Bioetanol dari Hidrolisat Pati Sagu (Metroxylon sp.) Menggunakan Saccharomyces Cerevisiae Var.ellipsoides Pada Kultivasi Nir-Sinambung dan Semi Sinambung:
Abstrak: Starch of sago is one of the sources of ethanol which is able to be produced by enzymatic hydrolysis and followed by cultivation process. It has high concentration of carbohydrate (80 %), so it can produce glucose highly with enzymatic hydrolysis process. The total amount of glucose has correlation with amount of ethanol, in cultivation process. The first step of research was to prepare substrate from sago starch which was hydrolysed enzymatically using α- amylase and amyloglucosidase (AMG) enzymes. Preliminary research was conducted to determine optimum concentration in which S.cerevisiae var.ellipsoides can live and produce the highest ethanol content. The concentrations being tested were 18, 24, 30 and 36 % (g/L) of total sugar. The main research consists of two systems: batch and fed-batch. Result shows that 24 % concentration (g/L) was find to be the optimum consentration for S.cerevisiae var.ellipsoides with ethanol production reaches up to 10,2 ± 0,000 % (w/v). One of the main research is using batch cultivation. The best result of highest ethanol concent was reached (10,77 ± 0,000 % w/v) when aeration was stopped after biomass condition has reached the maximum condition. The best result on fed-batch cultivation with the highest ethanol concentration (12,05 ± 0,00 % w/v) also was gained at the same treatment with feed concentration of glucose 16 % g/L. Based on calculation of cultivation kinetic parameters, it is shown that in batch cultivation the highest Yp/s, Yp/x (0,15; 0,47; 4,48) was gained on the third treatment that is aeration stopped at 30th hour. On fed-batch cultivation, the highest Yp/s and Yp/x value (0,51 and 5,05) is shown on treatment of which aeration is stopped after 30th hour and feed concentration of 16 % g/L.
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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