Judul: Klasifikasi Sedimen Berdasarkan Nilai Intensitas Hamburbalik Dasar Perairan Menggunakan Multibeam Echosounder di Perairan Selatan Pulau Biak
Abstrak: Multibeam echosounder (MBES) merupakan teknologi hidroakustik yang dapat menghasilkan batimetri dan intensitas hamburbalik dasar perairan yang dapat dimanfaatkan menjadi peta klasifikasi sedimen. Pesisir Biak Kota merupakan penghubung utama antara Pulau Biak dengan pulau lain sehingga dibutuhkan data MBES sebagai pendukung pembangunan atau pengelolaan sumberdaya bawah laut. Tujuan penelitian ini adalah menghasilkan peta klasifikasi sedimen di Perairan Selatan Pulau Biak menggunakan MBES Teledyne Reson T-50P dengan frekuensi 400 kHz. Batimetri diolah menggunakan metode Combined Uncertainty and Bathymetry Estimator (CUBE), intensitas hamburbalik diolah menggunakan metode SIPS Backscatter, dan klasifikasi sedimen dibuat berdasarkan rentang intensitas hamburbalik penelitian terdahulu. Batimetri menunjukan bagian perairan dangkal dengan kedalaman 1 – 40 meter dan perairan dalam dengan kedalaman 40 – ±236 m. Hasil intensitas hamburbalik perairan menunjukan rentang nilai -8,1 – 76,6 dB. Perairan dangkal dekat pesisir dengan kedalaman 1 – ±40 meter menunjukan kelas sedimen pasir sangat kasar, pasir kasar, pasir sedang, pasir halus, pasir sangat halus, pasir berlempung, pasir berlumpur, pasir berlanau, lanau kasar, dan lanau sedang. Perairan dalam dengan kedalaman 40 – ±236 meter menunjukan kelas sedimen lanau halus, lanau sangat halus, lanau berpasir, lempung, lempung berpasir, lempung berlanau, lempung berlumpur, dan lumpur.
Keyword: intensitas hamburbalik, klasifikasi sedimen, multibeam echosounder, sedimen perairan

Judul: Analisis Nilai Intensitas Hamburbalik Multibeam Echosounder untuk Klasifikasi Sedimen di Pulau Damar Besar, Kepulauan Seribu
Abstrak: Salah satu teknologi hidroakustik yang dapat digunakan untuk klasifikasi dan memetakan jenis sedimen dasar perairan adalah multibeam echosounder (MBES). MBES memancarkan lebih dari satu beam dengan pola pancaran melebar dan memanjang dari badan kapal. Penggunaan MBES dapat menghasilkan data hamburbalik yang mampu menentukan jenis dasar perairan. Tujuan penelitian ini untuk mengklasifikasi sedimen dasar perairan Pulau Damar Besar. Klasifikasi sedimen dilakukan dengan melihat nilai intensitas hamburbalik dan ditentukan jenis sedimen berdasarkan nilai rentang hamburbalik dalam pembagian kelas yang sudah ada pada data penelitian terdahulu. Selain itu klasifikasi sedimen ditentukan berdasarkan visual dan tesktur dari pengambilan sedimen di lapang. Sedimen dasar perairan Pulau Damar Besar dapat diklasifikasikan menjadi 8 kelas dengan rentang nilai hamburbalik yaitu lumpur halus -34.92 dB s/d -33.01 dB, lumpur sedang -32.99 dB s/d -31.01 dB, lumpur kasar -30.99 dB s/d -30.55 dB, pasir lanauan -28.99 dB s/d -27 dB, pasir berlumpur -26.99 dB s/d -25 dB, pasir liat -24.99 dB s/d -23 dB, pasir sangat halus -22.99 dB s/d -21.01 dB, dan pasir halus -20.99 dB s/d -19.04 dB., One of hydroacoustic technology that can be used to classify and map the type of bottom water sediment is multibeam echosounder (MBES). MBES emits more than one beam with a scatter pattern widening and extending from the ship's body. The use of MBES can produce backscatter data that is able to determine the type of bottom water. The purpose of this study was to classify the sediments of Damar Besar Island bottom water. Sediment classification was carried out by looking at the value of backscatter intensity and determining the type of sediment based on the value of the scattering range in the class division that already exists in the previous research data. In addition, the classification of sediments was determined on the basis of visuals and texture from taking sediments in the research location. The sediment of the bottom water of Damar Besar Island can be classified into 8 classes with a backscatter intensity value range, namely fine silt -34.92 dB to -33.01 dB, medium silt -32.99 dB to -31.01 dB, coarsed silt -30.99 dB to -30.55 dB, silty sand -28.99 dB to -27 dB, muddy sand -26.99 dB to -25 dB, clayed sand -24.99 dB to -23 dB, very fine sand -22.99 dB to -21.01 dB, and fine sand -20.99 dB to -19.04 dB.
Keyword: backscatter intensity, sediment classification, multibeam echosounder, Damar Besar Island, bottom water sediment

Judul: Characterization of The Chemical Constituents and Antioxidant Capacity of Green and Oolong Teas (Camellia sinensis) Manufactured in Thailand
Abstrak: Tea in Thailand most manufactured in northern area, especially Chiang Rai, Chiang Mai, Nan, and Mai Hang Son province. The aim of this study was to determine and compare the chemical compositions and antioxidant capacity of 4 important Thai tea products. A total of 13 of green teas of 2 major cultivars, assamicaand cv. oolong no.12 (chin hsuan oolong) and 26 of oolong tea of 2 major varieties, cv. oolong no. 12 and cv. oolong no. 17 (chin shin oolong) were collected from 18 factories in Chiang Rai province in 2011. The total polyphenol content was determined according to International Organization for Standardization (ISO 14502-1). For antioxidant capacity, DPPH radical scavenging activitiy assay and ferric reducing antioxidant power assay were determined. The catechins content and caffeine content were determined using HPLC by ISO method (ISO-14502-2). Results showed that about 95% of the 39 tea samples manufactured in Thailand had moisture content below 7%, 5% of tea samples being above 7%. The total polyphenol content in green tea was found to vary from 11.86 to 21.19%GAE, while in oolong tea was found in a range of10.22 to 17.57%GAE. The caffeine content in green tea samples were in a range of 1.69 to 3.7%, while in oolong tea samples were in a range of 1.61 to 3.26%. The catechin content in green tea samples were in a range of 8.31-14.08%, while in oolong tea samples were in a range of 6.81-12.46%. The antioxidant capacity in green tea samples was 164.01 mmole TE/100 g dry basis, while in oolong tea samples was about 132.73mmole TE/100 g dry basis. This study provided useful information for the tea industry in Thailand and other countries in processing and selecting a good-quality tea.
Keyword: Antioxidant capacity, Camellia sinensis, Green tea, Oolong tea, Thailand