This study reports for the first time the theoretical prediction of structural, electronic, elastic and optical properties of cubic BaLiCl3, BaLiBr3, and BaLiI3 perovskites. The corresponding properties of the well-known BaLiF3 are also theoretically investigated. Density Functional Theory (DFT) using the Generalized Gradient Approximation (GGA) was implemented within the Quantum Espresso package to investigate the properties of the perovskites. The results revealed that BaLiX3 (X = F, Cl, Br, and I) are in ionic crystal forms with optimized lattice parameters of 4.04, 4.90, 5.21, and 5.66 Å, respectively. The minor band gaps were found to be 6.62 eV (Γ→Γ), 4.29 eV (R→Γ), 3.50 eV (R→Γ), and 2.58 eV (R→Γ) for the respective compounds. The investigation of their elastic properties indicated that these perovskites are all mechanically stable, while only BaLiBr3 and BaLiI3 are malleable. Finally, the studied perovskites exhibit excellent optical properties, including low reflectivity and high absorption in the ultraviolet region. Hence, it is predicted that these perovskites are suitable for various optoelectronic applications involving absorption in the UV region. However, BaLiBr3 and BaLiI3 are more favorable than BaLiF3 and BaLiCl3 to be deposited as thin films due to their flexibility.

Abstrak Telah ditentukan celah energi optik ekstrak daun alpukat (Persea Americana Mill) asal Desa Oinlasi menggunakan metode Tauc plot. Penentuan nilai celah energi ditentukan untuk 3 kemungkinan jenis transisi yaitu direct transition, indirect transition, dan direct forbidden transition. Berdasarkan perhitungan menggunakan metode Tauc plot, celah energi rata-rata yang diperoleh untuk masing-masing transisi secara berturut-turut adalah 1,834 eV, 1,829 eV, dan 1,835 eV. Berdasarkan nilai celah energi senyawa hasil ekstrak daun alpukat dapat dikelompokkan sebagai bahan semikonduktor. Oleh karena itu, disimpulkan bahwa ekstrak daun alpukat berpotensi digunakan sebagai bahan alternatif piranti elektronik. Kata kunci : Daun alpukat, celah energi, semikonduktor, Tauc plot Abstract A study on determination optical energy gap of avocado leaves extract (Persea Americana Mill) from Oinlasi Village using Tauc plot method has been done. Determination of energy gap value was done for 3 possible transition types : direct transition, indirect transition, and direct forbidden transition. Based on calculations using Tauc plot method, energy gap average obtained for each transition are 1,834 eV, 1,829 eV, and 1,835 eV, respectively. Based on this energy gap value, the compound of avocado leaves extract can be categorized as a semiconducting material. Therefore, it can be concluded that avocado leaves extract has the potential to be used as alternative materials in electronic devices. Keywords : avocado leaves, energy gap, semiconductor, Tauc plot

Abstrak Telah dilakukan penelitian interpretasi pola penyebaran batuan dan daerah terakumulasi air tanah menggunakan metode magnetik di Desa Oematnunu Kabupaten Kupang. Tujuan penelitian ini untuk mengetahui pola sebaran batuan dan daerah terakumulasinya air tanah serta membuat pemetaannya. Akuisisi data dilakukan dengan Proton Precession Magnetometer (PPM) tipe GSM–19T dan data yang diperoleh berupa nilai medan magnet total serta variasi harian yang diolah serta diinterpretasikan secara kualitatif dan kuantitatif. Interpretasi kualitatif menunjukkan nilai anomali medan magnet total berkisar -250 nT sampai 450 nT dan terbagi atas anomali medan magnet rendah pada kisaran -250 nT sampai -10 nT, anomali medan magnet sedang dengan kisaran nilai -10 nT sampai 110 nT serta anomali medan magnet tinggi di kisaran 110 nT sampai 450 nT. Untuk  interpretasi kuantitatif menunjukkan struktur batuan yang diduga berupa batu pasir (aquifer) berada di bagian utara hingga barat laut dengan kedalaman sekitar 0 m - 100 m. Kata kunci: Metode magnetic; suspeptibilitas; akuifer; Oematnunu Abstract Interpretation of rock distribution patterns and areas groundwater accumulation using magnetic methods in Oematnunu Village Kupang District. The purpose of this research was to determine the pattern distribution of rocks and areas of groundwater accumulation and to make the mapping. The acquisition data was carried out by using the GSM-19T Proton Precession Magnetometer (PPM) and the data obtained in the form of total magnetic field values and daily variations were processed and interpreted qualitatively and quantitatively. The qualitative interpretation shows the total magnetic field anomaly values ranging from -250 nT to 450 nT and is divided into low magnetic field anomalies in the range -250 nT to -10 nT, moderate magnetic field anomalies with values ranging from -10 nT to 110 nT, and high magnetic field anomalies. in the range 110 nT to 450 nT. For quantitative interpretation, it shows the rock structure which is thought to be sandstone (aquifer) in the north to the northwest with a depth of about 0 m - 100 m.Keywords: Magnetic method; suspension; aquifer; Oematnunu

Waste materials continue to increase and have become a major problem in many countries. In this work,waste was recycled to form bioplastic composites. The study focused on the bioplastic (starch-cellulose acetate)-carbon material composites. The Graphene Oxide (GO) and Carbon-dots (CD) were chosen as filler materials. The physical properties of these bioplastics were investigated using tensile test, water uptake test and biodegradation test. Results showed that the addition of GO and CD reduced the tensile strength and elongation. It was also found that the water uptake decreased while the biodegradation rate increased with GO or CD addition. The interaction between the bioplastic starch-cellulose acetate matrix and the carbon materials as fillers can change the mechanical properties of the bioplastics. The carbon materials fill in the pores in bioplastics and make the bioplastic more waterproof and their hydrophilic properties attract water faster and help the activation of microbial activity during the biodegradation.

Telah dilakukan penelitian untuk mengetahui pola anomali magnetik dan perlapisan batuan bawah permukaan yang diduga berasosiasi dengan mineral logam pada daerah Fatunisuan Kecamatan Miomaffo Barat Kabupaten Timor Tengah Utara. Interpretasi kualitatif dari hasil penelitian memperlihatkan pola anomali magnetik di lokasi penelitian bernilai sekitar -60 nT sampai 160 nT yang terbagi atas anomali rendah (-160 nT sampai 0 nT) , anomali sedang (0 nT sampai 100 nT) dan anomali tinggi (100 nT sampai 160 nT). Untuk interpretasi kuantitatif dari sayatan A-A1, sayatan B-B1 dan sayatan C-C1 menunjukkan bahwa batuan yang memiliki nilai suseptibilitas terbesar, yaitu batugamping antara 0,00127 cgs sampai 0,00791 cgs diduga berasosiasi dengan mineral logam. Sebaran batugamping ini dapat ditemukan secara dominan pada sekitar arah barat daya, barat-barat daya, timur laut, timur-timur laut, barat, barat-barat laut dan Tenggara.