Judul: Variasi nilai target strength ikan gurame (Osphronemus goramy) sesuai tilt-angle
Abstrak: Ikan gurame (Osphronemus goramy) mengalami perubahan kebiasaan makan dan aktif berenang ke permukaan serta dasar perairan. Hidroakustik merupakan teknologi yang digunakan untuk mendeteksi kondisi bawah air. Simrad EK-15 merupakan alat instrumen hidroakustik single beam yang digunakan untuk mengetahui nilai target strength. Target strength dipengaruhi oleh pergerakan dan gelembung renang ikan. Simrad EK-15 dengan frekuensi 200 kHz digunakan dalam penelitian untuk mengukur nilai target strength. Serangkaian percobaan dilakukan untuk mengetahui variasi nilai target strength dan titik puncak target strength dalam kaitannya dengan tilt-angle. Panjang total gurame 1,2,3 berturut-turut yaitu 26 cm, 29.9 cm dan 32.3 cm. Berdasarkan metode tethered. Gurame 1 memiliki titik puncak rata-rata target strength sebesar -40.416 dB. Gurame 2 memiliki titik puncak rata-rata target strength sebesar -36.849 dB. Gurame 3 memiliki titik puncak rata- rata target strength sebesar -35.836 dB. Pada gurame 1 rata-rata target strength tertinggi pada sudut 45° atau ke arah vertikal. Pada gurame 2 dan 3 rata-rata target strength pada sudut gurame 0° atau horizontal lebih tinggi dibandingkan dengan rata-rata target strength gurame pada sudut ke arah vertikal. Target strength rata-rata yang lebih tinggi dapat dijelaskan oleh pengaruh sudut kemiringan pada data target strength keseluruhan. Hasilnya dapat digunakan untuk memahami pengaruh sudut kemiringan terhadap target strength. Kata kunci: gurame, Oshpronemus goramy, Simrad EK-15, tilt angle, target strength, Goramy (Osphronemus goramy) has changed eating habits and actively swims to the surface and bottom of the waters. Hydroacoustic is a technology used to detect underwater conditions. Simrad EK-15 is a single beam hydroacoustic instrument used to determine the target strength value. The target strength is affected by the movement and swimming bubbles of the fish. Simrad EK-15 with a frequency of 200 kHz is used in this study to measure the value of target strength. A series of experiments were conducted to determine the variation in the value of the target strength and the peak point of the target strength in relation to the tilt-angle. The total length of goramy 1,2,3, respectively, is 26 cm, 29.9 cm and 32.3 cm. Based on the tethered method. Goramy 1 has a peak average target strength of -40,416 dB. Goramy 2 has a peak average target strength of -36,849 dB. Goramy 3 has a peak average target strength of -35,836 dB. In goramy 1 the highest average target strength is at an angle of 45° or in the vertical direction. In goramy 2 and 3 the average target strength of goramy at an angle of 0° or horizontal is higher than the average target strength of goramy at an angle to the vertical. The higher average target strength can be explained by the influence of the slope angle on the overall target strength data. The results can be used to understand the effect of slope angle on target strength. Keywords: goramy, Oshpronemus goramy, Simrad EK-15, tilt angle, target strength
Keyword: target strength, tilt-angle, oshpronemus goramy, ikan gurame, Simrad EK-15

Judul: Target Strength Measurement of Snakehead Fish (Channa striata Bloch 1793) Juveniles Using Hydroacoustic Method under Controlled Conditions
Abstrak: Ikan Gabus (Channa striata) merupakan ikan karnivora yang banyak ditangkap karena rasa dagingnya yang gurih dan mudah ditemukan di perairan berlumpur, rawa-rawa, kolam, perairan sungai. Ikan gabus anakan lebih banyak ditangkap sebagai pakan untuk ikan hias lainnya, ancaman terhadap anakan gabus secara terus menerus dapat berakhir dengan kepunahan. Hal ini menjadi penting untuk menganalisa hubungan antara Target strength (TS) dengan panjang total anakan ikan gabus menggunakan instrumen echosounder SIMRAD EK15. Pengolahan data target strength 15 ikan gabus dengan rentang panjang badan 10-15 cm dilakukan dalam perangkat lunak echoview versi demo menggunakan metode digitasi per 1 ping dengan thresholding diantara -70 dB hingga -30 dB. Nilai TS yang diperoleh memiliki rata-rata -46.80 dB sampai -45.01 dB. Analisis hubungan antara panjang total dan nilai TS anakan ikan gabus memiliki hubungan yang sangat kuat yang ditunjukkan oleh koefisien regresi sebesar 85.31% dan persamaan TS= 64.439ln(L) – 215.66., Snakehead fish (Channa striata) is a carnivorous fish that is widely caught for the savory meat taste and easy to found in muddy waters, swamps, ponds, river waters. Snakehead fish juveniles are mostly caught as food for other ornamental fish, Threats that continuously run over the snakehead fish’s juveniles might makes them end up in extinction. It’s become important to analyse the relationship between Target Strength (TS) and the total length of snakehead fish’s juveniles using SIMRAD EK 15 echosounder. The target strength data of 15 snakehead fish with body length range of 10-15 cm is processed using the demo version of echoview by digitizing each ping and applying threshold between -70dB to -30dB. Results of the average value of TS ranged from -46.80 dB to -45.01 dB. The relationship between total length and TS value of snakehead fish has a strong relationship, which is indicated by regression coefficient of 85.31% and the equation TS = 64,439ln(L) – 215.66
Keyword: hydroacoustic, juvenile, SIMRAD EK 15, snakehead fish, target strength

Judul: Prenilasi Senyawa β-Diketon sebagai Prekursor 3-Prenilflavon
Abstrak: One group of flavonoids that has not been commonly synthesized is 3- prenylflavone. The main objective of this experiment was to synthesize precursor of 3-prenylflavone. Firstly, β-diketone was synthesized via 4 steps from phenol as starting compound with total yield of 24%. Prenylation of β-diketone with prenyl bromide and K2CO3 base produced 4 fractions which were separated by using preparative thin layer chromatography (PTLC) with n-hexane:EtOAc (8:2) as the eluent. Fraction with Rf = 0.80 was further separated by using preparative PTLC with n-hexane:EtOAc (99:1) as the eluent. Two fractions were obtained with Rf = 0.38 and 0.42. The first fraction has been characterized as diprenylated β-diketone with 49% yield. Application of protecting group on the phenolic OH group in β- diketone are needed to obtain monoprenylated β-diketone which can be further cyclized into 3-prenylflavone
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