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: Distibusi Nilai Target Strength Ikan Pelagis di Perairan Pancur, Kabupaten Lingga, Kepulauan Riau
Abstrak: Perairan pancur merupakan pusat pengumpulan ikan hasil tangkapan nelayan. Mata pencaharian masyarakat di Pancur yaitu nelayan. Informasi mengenai stok ikan di perairan sangat penting. Metode akustik dapat digunakan untuk menentukan pendugaan stok ikan di suatu perairan. Nilai target strength dapat digunakan sebagai scaling factor dalam pendugaan stok ikan. Penelitian ini bertujuan menganalisis distribusi target strength dan pendugaan stok ikan Pengambilan data pada penelitian menggunakan SIMRAD EK-15 frekuensi 200 kHz dan pengolahan data menggunakan software Sonar4. Distribusi nilai target strength di setiap jalur tracking ditemukan ikan dengan ukuran dan jumlah yang berbeda-beda. Jumlah keseluruhan target yang terdeteksi yaitu sebanyak 84276 ekor ikan. Jumlah ikan yang paling banyak terdeteksi yaitu dengan nilai TS -68 dB sampai -65 dB sebanyak 39577 ekor sedangkan jumlah yang paling sedikit yaitu - 41 dB sampai -38 dB dengan jumlah sebanyak 141 ekor. Diduga nilai TS -68 dB sampai -59 dB merupakan ikan bilis (Stolephorus spp). Ikan dengan ukuran 12.32 cm sampai 49.54 diduga merupakan ikan selain ikan bilis, seperti ikan duri dan ikan lebam., The fountain is a center for collecting fish caught by fishermen. The livelihoods of the people in Pancur are fishermen. Information about fish stocks in the waters is very important. Acoustic methods can be used to determine the estimation of fish stocks in a waters. The target strength value can be used a scaling factor in estimatin fish stocks. This study aims to analyze the distribution of target strength and fish stock estimation. Data collection in this study used SIMRAD EK15 with a frequency of 200 kHz and data processing using Sonar4 software. The distribution of target strength values in each tracking path was found to be fish with different sizes and numbers. The total number of detected targets was 84276 fish. The highest number of fish detected was with a TS value of -68 dB to -65 dB as many as 39577 fish while the smallest number was -41 dB to -38 dB with a total of 141 fish. It is suspected that the target strength value -68 dB to -59 dB is an anchovy fish (Stolephorus spp). Fish with a size of 12.32 cm to 49.54 are suspected to be fish other than anchovies, such as thorn fish and bruising fish.
Keyword: blackfish, horizontal distribution, pancur, target strength, blackfish, horizontal distribution, Pancur, 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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