Judul: Analisis Karakteristik Nilai Hamburbalik Akustik Zooplankton Menggunakan Instrumen Acoustic Doppler Current Profiler (ADCP) di Laut Halmahera
Abstrak: Kajian mengenai karakteristik distribusi zooplankton penting dilakukan mengingat organisme tersebut memiliki peran penting di ekosistem laut sebagai konsumen tingkat satu dalam rantai makanan. Penelitian ini bertujuan menganalisis karakteristik nilai hamburbalik akustik zooplankton secara temporal dan spasial di Laut Halmahera menggunakan instrumen Acoustic Doppler Current Profiler (ACDP) tipe vessel-mounted dengan frekuensi 153,6 kHz. Pada penelitian ini juga dilakukan pengamatan kondisi perairan kajian melalui analisis data oseanografi dan batimetri. Data akustik dan oseanografi merupakan hasil survei Ekspedisi Jala Citra I “Aurora” tahun 2021 sedangkan data batimetri diunduh dari GEBCO. Data mentah hasil pemeruman ADCP berupa nilai digital (count) perlu dikonversi menjadi hamburbalik akustik atau Mean Volume Backscattering Strength / MVBS (dB) menggunakan persamaan sonar agar proporsional dengan biomassa zooplankton. Proses konversi meliputi koreksi terhadap pelemahan suara akibat pengaruh jarak terhadap objek dan penyerapan suara oleh medium air, koreksi jarak miring transduser ADCP, dan koreksi terhadap pengaruh derau. Organisme zooplankton pada data mentah ADCP berada pada rentang 70 – 160 count, sedangkan pada data MVBS hasil konversi berada pada rentang -86,50 dB sampai -62,64 dB. Pengamatan secara temporal menunjukkan terjadinya fenomena migrasi yaitu adanya agregasi zooplankton yang bergerak sesuai siklus harian matahari. Pada pengamatan secara spasial, kepadatan zooplankton lebih tinggi di lokasi perairan semi-tertutup. Pada lokasi perairan terbuka, terdapat fenomena migrasi vertikal harian yang dibuktikan dari karakteristik nilai hamburbalik akustik zooplankton sesuai dengan waktu pemeruman ADCP. Di sisi lain, pada pengamatan distribusi vertikal, MVBS zooplankton secara umum bernilai tinggi di lapisan permukaan dan menurun seiring pertambahan kedalaman. Penelitian ini membuktikan bahwa instrumen ADCP dapat digunakan untuk mengamati keberadaan dan tingkah laku zooplankton berdasarkan nilai hamburbaliknya., The study of the distribution characteristics of zooplankton is essential considering that these organisms have an important role in the marine ecosystem as first level consumers in the food chain. This study aims to analyze the temporal and spatial characteristics of zooplankton acoustic backscatter values in the Halmahera Sea using a vessel-mounted Acoustic Doppler Current Profiler (ACDP) instrument with a frequency of 153,6 kHz. This study also observed the condition of the study waters through oceanographic and bathymetric data analysis. Acoustic and oceanographic data are the results of the Jala Citra I "Aurora" survey expedition on 2021 while the bathymetry data is downloaded from GEBCO. The raw data result from ADCP is in the form of a digital value (count) that needs to be converted into acoustic backscattering or Mean Volume Backscattering Strength / MVBS (dB) using sonar equations so that it is proportional to zooplankton biomass. The conversion process includes correction for the attenuation of sound due to the effect of the distance to the object and sound absorption by the water medium, correction on the tilt distance of the ADCP transducer, and correction for the effect of noise. Zooplankton organisms in the raw ADCP data have a range between 70 – 160 count, while in the converted MVBS data they are in the range of -86,50 dB to -62,64 dB. Temporal observations show the phenomenon of migration where the aggregation of zooplankton moves according to the daily solar cycle. In spatial observation, the density of zooplankton is higher
Keyword: Acoustic backscatter, ADCP, Halmahera Sea, Zooplankton

Judul: Deteksi Nilai Hambur Balik Plankton di Laut Jawa dengan Hidroakustik 100 KHz
Abstrak: Plankton adalah biota yang berperan penting dalam ekosistem perairan. Kelimpahan dan ketersediaan plankton di Laut Jawa dapat dianalisa berdasarkan nilai hambur balik. Pada penelitian ini, kelimpahan plankton diukur memakai gelombang frekuensi 100 kHz dengan instrumen EK SIMRAD 70 Multifrekuensi Echosounder. Pengambilan data dilakukan pada 17 Oktober sampai 11 November 2017 di perairan Laut Jawa. Pengolahan data dilakukan untuk melihat sebaran plankton secara spasial dan temporal memakai software Echoview tipe 5.0 dengan nilai pembatas sebesar (threshold) -100 dB s/d -70 dB. Nilai dari plankton yang teridentifikasi pada setiap lapisan dengan frekuensi 100 kHz yaitu -99.28 dB hingga -86.11 dB. Distribusi horizontal nilai SV plankton dengan nilai rata-rata sebesar -92.06 dB. Distribusi vertikal dicatat setiap 5 meter lapisan perairan. Pada kedalaman 5 meter ditemukan nilai sebaran yaitu -99.74 dB hingga -83.97 dB. Nilai hambur balik terbesar berada pada kedalaman 45 m yaitu - 81.29 dB. Hubungan sebaran distribusi plankton terhadap waktu (temporal) dibagi kedalam 4 rentang waktu selama 24 jam dan dibandingkan dengan 2 lokasi berbeda. Analisis perbandingan nilai SV plankton secara temporal menunjukkan perubahan densitas plankton yang fluktuatif dari waktu ke waktu., Planktons are organisms that play an important role in the ecosystem. Abundancy and availability of plankton in Java Sea can be analyzed by backscattering strength volume. In this research, abundancy of plankton is measured by using 100 kHz frequency wave of Multifrequency Echosounder (ME) EK SIMRAD 70. Data collection was carried out on October 17 to November 11, 2017 in Java Sea. Data processing was aimed to know the spatial and temporal distribution of plankton by using Echoview type 5.0 with threshold around -100 dB to -70 dB. The value of plankton identified in each layer with a frequency of 100 kHz is -99.28 dB to -86.11 dB. The distribution of plankton value is -92.06 dB horizontally. While vertical distribution is divided into several depth group. The first 5 meters is -99.74 dB to - 83.97 dB. The highest value of backscattering is found at 45 m which is -81.29 dB. Corelation of distribution versus time is split into 4 time ranges during 24 hours and compared into 2 different locations. The comparative analysis of plankton SV values in temporal terms shows a fluctuating change in plankton density from time to time.
Keyword: Densitas, Distribusi, Frekuensi, Laut Jawa, Plankton, Density, Distribution, Frequency, Java Sea, Plankton

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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