Judul: Synthesis and Characterization of Fluorapatite Based on Golden Snail Shell with Precipitation and Solid-State Reaction Method
Abstrak: Pemasangan implan sebagai benda asing dalam tubuh sering kali mengalami reaksi penolakan oleh tubuh. Hal tersebut dapat dihindari melalui pelapisan implan dengan fluorapatit (FAp). Salah satu faktor keberhasilan sintesis FAp ditentukan oleh metode sintesis. Penelitian ini bertujuan menyintesis FAp dengan metode presipitasi (FAp-P) dan solid-state reaction (FAp-SS) berbahan dasar cangkang keong emas. Penelitian dilakukan melalui tiga tahap, yaitu preparasi sampel, sintesis FAp, dan karakterisasi FAp dengan X-ray diffraction (XRD), fourier transform infrared (FTIR), dan scanning electron microscope-energy dispersive X-ray (SEM-EDX). Hasil XRD menunjukkan kristalinitas yang baik untuk kedua metode. FAp-SS menghasilkan spektrum FTIR yang lebih mirip dengan spektrum FAp dibandingkan dengan FAp-P. Hasil SEM menunjukkan morfologi sampel FAp-SS lebih seragam dibandingkan FAp-P. Di samping itu, EDX mengonfirmasi rasio Ca/P dari FAp-P sebesar 1,84 dengan P/F 2,00 sedangkan rasio Ca/P dari FAp-SS sebesar 1,86 dengan P/F 2,94. Hasil tersebut mengonfirmasi metode solid-state reaction lebih mendekati standar FAp, yaitu Ca/P 1,67 dan P/F 3,00., Implant placement as a foreign object in the body often experiences a rejection reaction by the body. It can be avoided through implant coating with fluorapatite (FAp). One factor that determines FAp's successful synthesis is the synthesis method. This study aims to synthesize FAp by precipitation method (FAp-P) and solid-state reaction (FAp-SS) made from golden snail shells. The research was conducted through three stages, which are sample preparation, FAp synthesis, and FAp characterization with X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscope-energy dispersive X-ray (SEM-EDX). XRD results showed good crystallinity for both methods. FAp-SS produced an FTIR spectrum that was more similar to the FAp spectrum compared to FAp-P. SEM results showed that the morphology of FAp-SS was more uniform than FAp-P. In addition, EDX confirmed that the Ca/P ratio of FAp-P was 1.84 with a P/F of 2.00, while the Ca/P ratio of FAp-SS was 1.86 with a P/F of 2.94. These results confirm that the solid-state reaction method is closer to the FAp standard, namely Ca/P 1.67 and P/F 3.00.
Keyword: cangkang keong emas, fluorapatit, presipitasi, solid-state reaction

Judul: Synthesis and Characterization of Fluorapatite with pH Variations Based on Rice Fields Snail Shells Using the Precipitation Method
Abstrak: Kerusakan pada gigi biasanya membutuhkan pengganti berupa gigi buatan, yaitu implan gigi. Salah satu bahan utama pembuatan implan gigi adalah fluorapatit (FAp) yang dapat berasal dari limbah cangkang keong sawah sebagai prekursor berupa kalsium hidroksida pada sintesis FAp. Penelitian ini bertujuan menyintesis dan mengkarakterisasi FAp berbasis cangkang keong sawah dengan metode presipitasi menggunakan variasi pH. Metode penelitian ini dilakukan melalui tiga tahap, yaitu preparasi sampel cangkang keong sawah, sintesis FAp dengan tiga variasi pH berbeda (5, 7, dan 9) menggunakan metode presipitasi dan karakterisasi FAp dengan X-ray diffraction (XRD). Hasil karakterisasi terbaik dilanjutkan dengan fourier transform infrared (FTIR) dan scanning electron miroscope energy dispersive X-ray (SEM-EDX). Hasil penelitian menunjukkan bahwa dari tiga variasi pH, maka FAp dengan pH 9 memiliki hasil yang terbaik berdasarkan hasil XRD (kristalinitas, ukuran kristal, fase kristal) dan rendemen. FAp pH 9 terbukti memiliki gugus fungsi -OH, OH-F, dan -PO43- yang sesuai dengan analisis FTIR. FAp dengan pH 9 juga terbukti memiliki morfologi permukaan yang seperti gumpalan dan rasio molaritas Ca/P sebesar 3,59 dan P/F sebesar 5,83 dengan analisis SEM-EDX., Damage to the teeth usually requires replacement in the form of artificial teeth, namely dental implants. One of the main ingredients for making dental implants is fluorapatite (FAp) which can be derived from rice snail shell waste as a precursor in the form of calcium hydroxide in FAp synthesis. This study aims to synthesize and characterize FAp based on rice field snail shells with the precipitation method using variations in pH. This research method was carried out in three stages, namely preparation of rice snail shell samples, synthesis of FAp with three different pH variations (5, 7, and 9) using the precipitation method, and FAp characterization by X-ray diffraction (XRD). The best characterization results were followed by fourier transform infrared (FTIR) and scanning electron microscopy energy dispersive X-ray (SEM-EDX). The results showed that of the three variations of pH, FAp with pH 9 had the best results based on XRD results (crystallinity, crystal size, crystal phase) and yield. FAp pH 9 proved to have functional groups -OH, OH-F, and -PO43- which was by FTIR analysis. FAp with pH 9 was also shown to have a lump-like surface morphology and a Ca/P molarity ratio of 3,59 and P/F of 5,83 by SEM-EDX analysis.
Keyword: Dental Implant, Fluorapatite, Precipitation, Rice Fields Snail Shell

Judul: Utilization of terra/MODIS L1B data for analysis of horizontal wind profile in the troposphere
Abstrak: This study was concerned with horizontal wind derived from data collected with the Moderate-resolution Imaging Spectroradiometer (MODIS) on board the NASA’s Earth Observation System (EOS)-Terra satellite. The aim of this study is to develop a method for the estimation of horizontal wind movement in the troposphere based on Navier-Stokes equation. The method was applied to a calibrated and geolocated Terra/MODIS L1B 1 km data set. The data inputs to estimate surface temperature are retrieved from TIR (Thermal Infrared) bands 31 (10.780 μm to 11.280 μm) and 32 (11.770 μm to 12.270 μm). The obtained surface temperatures were later used to approximate geopotential height on a constant-pressure surface by using the modified Poisson equation. The main assumptions used are the hydrostatic equilibrium, ideal gas law, constant lapse rate and constant acceleration of gravity. Based on the distribution of geopotential height, the pressure gradient force is measured by the gradient of geopotential on an isobaric coordinate to present the horizontal wind profile. For certain topographic areas especially in the mountain ranges, there was a disadvantage of using pressure as a vertical coordinate which lead to inaccuracy. In spite of that, Terra/MODIS L1B data with 1 km spatial resolution can be used to estimate the horizontal wind movement in the troposphere.
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