Judul: Efek Modifikasi π-Spacer dan Akseptor terhadap Sifat Elektronik dan Optik Galangin sebagai Zat Pemeka Sel Surya
Abstrak: Energi matahari menjadi sumber energi listrik alternatif yang dapat dipanen menggunakan Dye Sensitized Solar Cells (DSSC). Eksplorasi sifat elektronik dan optik pewarna menjadi penting mengingat performansi DSSC bergantung juga pada performansi pewarna yang digunakan. Perbaikan performansi pewarna dapat dilakukan dengan memodifikasi strukturnya. Studi ini mengeksplorasi performansi galangin termodifikasi secara komputasi menggunakan DFT dengan level teori B3LYP dan basis set def2-SVP. Modifikasi dilakukan dengan memvariasikan tiofena dan furan sebagai π-spacer serta 4-etinil asam benzoat dan asam sianoasetat sebagai akseptor. Molekul dengan tiofena dan asam sianoasetat memiliki performansi paling baik ditinjau dari sifat elektroniknya. Sifat optiknya yang kurang optimal diatasi dengan memvariasikan jumlah gugus π-spacer yang digunakan. Molekul dengan 2 gugus tiofena memberikan performansi yang lebih baik lagi. Hal ini berkaitan dengan efektivitas delokalisasi elektron π pada tiofena dan kemampuan penarikan elektron yang dimiliki asam sianoasetat. Molekul ini sudah sangat layak untuk diterapkan sebagai pewarna, karena karakteristik elektronik dan optiknya sudah baik., Solar energy is an alternative source of electrical energy that can be harvested using Dye-Sensitized Solar Cells (DSSC). Exploration of the electronic and optical properties of dyes is important because performance of DSSCs also depends on the dye’s performance. Performance of dye can be improved by modifying its structure. This study computationally explores the performance of modified galangin using DFT with B3LYP theory level and def2-SVP basis set. Modifications were made by varying thiophene and furan as π-spacers also 4-ethynyl benzoic acid and cyanoacetic acid as acceptors. Molecule with thiophene and cyanoacetic acid has the best performance in terms of their electronic properties. Its optical properties were overcomed by varying the number of π-spacer groups used. Molecules with 2 thiophene groups give even better performance. This is related to the effectiveness of π-electron delocalization in thiophene and the electron-withdrawing ability of cyanoacetic acid. This molecule is very feasible to be applied as a dye, because its electronic and optical characteristics are very good.
Keyword: absorption spectra, DFT, DSSC, energy gap, galangin

Judul: The Performance of Dye Sensitized Solar Cell (DSSC) with Mangosteen Rind Extract and Papaya Leaf Extract Natural Dye Mixture
Abstrak: Pewarna alami secara umum memiliki rentang absorpsi cahaya yang lebih sempit dari pewarna sintetis, sehingga efisiensi konversi energi dye sensitized solar cell (DSSC) yang dihasilkan lebih kecil. Pencampuran pewarna memiliki potensi untuk memperluas area absorpsi cahaya. Penelitian ini bertujuan menganalisis kinerja DSSC berbahan dasar pewarna alami campuran ekstrak kulit manggis dan daun pepaya. Pewarna dipreparasi dengan metode maserasi dan diperoleh tiga jenis pewarna, yaitu ekstrak kulit manggis, ekstrak daun pepaya, dan campuran keduanya dengan tiga rasio volume berbeda. Elektrode kerja merupakan kaca indium tin oxide (ITO) dengan semikonduktor TiO2 yang direndam dalam pewarna. Elektrode lawan adalah kaca ITO yang dilapisi grafit. Elektrolit polimer dipreparasi dengan mencampurkan larutan elektrolit iodida/triiodida dengan polistirena tersulfonasi. Pencampuran pewarna terbukti dapat meningkatkan efisiensi konversi energi DSSC. Pewarna campuran ekstrak kulit manggis dan daun pepaya dengan rasio 3:1 memberikan efisiensi konversi energi terbesar, yaitu 1,97%., Most natural dyes have narrower light absorption wavelength ranges than synthetic dyes, resulting in dye sensitized solar cells (DSSC) with lower energy conversion efficiency. Mixing natural dyes can widen the light absorption area. This research aims to analyze the performance of DSSCs with mixed natural dyes of mangosteen rind extract and papaya leaf extract. The dye was prepared by maceration. Three varieties of dyes were obtained, which are mangosteen rind extract, papaya leaf extract, and the mixture of both in three different volume ratios. The working electrode is an ITO glass with TiO2 semiconductor, immersed in dye. The counter electrode is an ITO glass with a thin graphite layer. Polymer electrolyte was prepared by mixing an iodide/triiodide electrolyte solution with sulfonated polystyrene. Mixing of dyes is proven to be able to increase the energy conversion efficiency of DSSC. Mixed dye of mangosteen rind extract and papaya leaf extract with 3:1 volume ratio yielded the highest energy conversion efficiency of 1,97%.
Keyword: DSSC, mangosteen rind, mixed dye, papaya leaf, sulfonated polystyrene

Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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