Judul: Karakteristik Gelombang Internal di Laut Bali dari Data Sentinel-1A dan Pemodelan Laut
Abstrak: Gelombang internal yang merambat ke Laut Bali diduga berasal dari bagian selatan Selat Lombok, dimana terdapat ambang laut (sill) Nusa Penida sebagai area pembangkitan gelombang internal. Pendeteksian rona permukaan gelombang internal dapat menggunakan citra satelit radar Sentinel-1A serta pemodelan sirkulasi laut CROCO. Penelitian ini bertujuan untuk mendeskripsikan rona permukaan dari gelombang internal, serta mendeskripsikan mekanisme pembentukan dan penjalaran gelombang internal di Laut Bali. Citra radar menunjukkan paket gelombang internal di Laut Bali tersebar di dua wilayah, yaitu di wilayah pembangkitan yaitu di dekat Selat Lombok, dan di wilayah propagasi yaitu di bagian barat dan utara Laut Bali. Panjang puncak gelombang internal semakin meningkat seiring pergerakan gelombang ke wilayah propagasi. Laut Bali memiliki tipe pasang surut campuran cenderung ganda, dengan pergerakan ke arah utara dan selatan secara bergantian pada fase pasang dan surut secara berturut-turut. Arus meridional di wilayah sill dominan bergerak ke arah utara pada fase pasang menuju surut dan mengakibatkan peningkatan kedalaman piknoklin pada bagian utara sill hingga kedalaman 400 m. Penelitian ini menunjukkan adanya pergerakan arus ke arah atas dan bawah secara bergantian setelah arus melewati sill dan membuktikan terbentuknya puncak dan lembah dari gelombang internal., Internal waves (IWs) that propagate into Bali Sea are expected to originate from the southern part of Lombok Strait, which has Nusa Penida sill as IWs generating area. IWs detection was carried out using Sentinel-1A radar satellite imagery and CROCO ocean circulation modeling. This study aims to describe the surface hue of the IWs, also describe the mechanism of IWs formation and propagation in Bali Sea. The radar image shows that wave packets are spread over two areas, namely in the generation area near Lombok Strait, and in the propagation area, namely in the western and northern parts of Bali Sea. The IWs crest length will increase as it moves into the propagation region. Bali Sea has a mixed semidiurnal tidal type, with currents in the sill area move north and south alternately during the high and low tide phases. Meridional currents in the sill area move northward during the high to low tide phase, resulting in the subsidence of the pycnocline in the northern part to 400 m. This study shows an alternating upward and downward movement of vertical currents in the northern part of the sill and indicate the occurrence of peaks and valleys of IWs.
Keyword: Bali Sea, CROCO, internal wave, sill, Sentinel-1A

Judul: Internal Wave Detection and Quantification Using SIMRAD EK80 Broadband Echosounder Instrument in Padang Bay Waters Bali
Abstrak: Internal wave adalah peristiwa yang terjadi di laut dangkal dan laut dalam, dimana kemunculan internal wave hanya dapat terjadi jika kolom air terstratifikasi akibat adanya perbedaan densitas massa air. Penelitian ini bertujuan mendeteksi peristiwa internal wave, serta mengukur nilai acoustic backscatter dari internal wave terjadi di Selat Lombok. Data yang digunakan adalah hasil pengukuran instrument broadband echosounder SIMRAD EK80 frekuensi 200 kHz tipe pulsa continuous wave (CW) dengan data pendukung elevasi muka air, suhu, salinitas, dan densitas dari Conductivity Temperature Depth (CTD) “yoyo” selama 24 jam. Nilai hambur balik didapatkan dengan analysis menggunakan perangkat lunak Sonar5-Pro. Echogram menunjukkan adanya pembentukan nonlinearinternal wave disertai dengan adanya turbulent terjadi pada saat gelombang pasang membawa massa air dengan densitas berbeda melewati topografi kasar di Selat Lombok. Nilai backscatter hasil segmentasi berentang dari -75 dB sampai -59 dB., Internal waves are events that occur in shallow sea and deep sea, where the appreanced of internal waves can only occurs if the water column is stratified due to differences in water mass density. This study aimed to detect internal wave events, as well as measure the acoustic backscatter value of internal waves occurring in the Lombok Strait. The data used is the measurement result of SIMRAD EK80 broadband echosounder instrument with frequency of 200 kHz continuous wave (CW) pulse type with supporting data for water level elevation, temperature, salinity, and density from Conductivity Temperature Depth (CTD) “yoyo” for 24 hours. The backscatter value was obtained by analysis using the Sonar5-Pro software. Echogram showed the formation of nonlinear internal waves accompanied by the presence of turbulence that occur when high tidal waves carry water masses from different density through rough topography in Lombok Strait. The backscatter value of the segmentation results range from -75 dB to -59 dB.
Keyword: Backscatter, Broadband, Continuous Wave, Internal Wave, Tidal Wave

Judul: Sintesis dan Pencirian Kompleks Fe(III)-Kuersetin
Abstrak: Quercetin belongs to flavonols which is able to chelate metal ions. Quercetin may chelate metal ions at 3’,4’-catechol, 3- or 5-hydroxycromone sites. In this study, quercetin was complexed with Fe(III). The complex with Fe(III) ions from FeCl3·6H2O was more stable than the complex derived from Fe(NO3)3·9H2O. The quercetin was yellow in color and showed maximum wavelengths (λ􀭫􀭟􀭶) at 250 and 370 nm. The Fe(III)-quercetin complex from Fe(NO3)3·9H2O was yellowish green with 􀟣􀭫􀭟􀭶 at 280 and 420 nm, whereas that from FeCl3·6H2O was dark green with 􀟣􀭫􀭟􀭶 at 280 and 430 nm. The 􀟣􀭫􀭟􀭶 shift indicated that the complex was formed at 3-hydroxychromone site. The Fe(III)- quercetin complex was formed with 1:1 metal-ligand mole ratio based on atomic absorption spectrophotometry analysis and the X-ray diffractogram showed that the crystallinity of the complex was 37%.
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