Judul: Synthesis and Characterization of Fluorapatite with Variations in Sintering Temperature Based on Rice Snail Shells Using the Precipitation Method
Abstrak: Kerusakan pada gigi merupakan salah satu contoh kurangnya unsur kalsium pada tubuh kita, karena kalsium berperan dalam perkembangan tulang dan gigi. Cangkang keong sawah dapat digunakan sebagai prekursor untuk pembentukan fluorapatit (FAp). Penelitian ini bertujuan menyintesis dan mengkarakterisasi FAp dari cangkang keong sawah dengan metode presipitasi serta mengetahui pengaruh variasi suhu sintering. Metode penelitian ini dilakukan melalui tahapan preparasi cangkang keong sawah, Sintesis FAp dengan variasi suhu sintering (600 °C, 800 °C, dan 1000 °C) dengan metode presipitasi. Hasil sintesis FAp dikarakterisasi dengan X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) serta Scanning Electron Microscope Energy Dispersive X-Ray (SEM-EDX). Hasil penelitian menunjukkan bahwa fluorapatit yang disintering dengan suhu 1000 °C memiliki nilai kristalinitas yang paling tinggi berdasarkan hasil XRD. Spektrum FTIR dari FAp suhu 1000 °C diidentifikasi memiliki gugus -OH, OH-F, dan -PO43-. Hasil analisis SEM-EDX menunjukkan fluorapatit dengan suhu 1000 °C memiliki bentuk seperti batang dan jarum serta memiliki rasio molaritas Ca/P sebesar 13,18 dan P/F sebesar 4,29., Synthesis and Characterization of Fluorapatite with Variations in Sintering Temperature Based on Rice Snail Shells Using the Precipitation Method. Supervised by IRMA HERAWATI SUPARTO and CHARLENA Tooth decay is an example of a lack of calcium in our bodies, because calcium plays a role in the development of bones and teeth. Rice snail shells can be used as a precursor for forming fluorapatite (FAp). This study aims to synthesize and characterize FAp from rice field snail shells using the precipitation method and to determine the effect of variations in sintering temperature. This research method was carried out through the stages of preparation of rice snail shells, FAp synthesis with various sintering temperatures (600 °C, 800 °C, and 1000 °C) with the precipitation method. The results of the FAp synthesis were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) and Scanning Electron Microscope Energy Dispersive X-Ray (SEM-EDX). The results showed that fluorapatite sintered at 1000 °C had the highest crystallinity value based on XRD results. The FTIR spectrum of FAp at 1000 °C was identified as having -OH, OH-F, and -PO43- groups. The results of SEM-EDX analysis showed that fluorapatite at a temperature of 1000 °C had a shape like rods and needles and had a Ca/P molarity ratio of 13.18 and P/F of 4.29.
Keyword: Fluorapatite, Crystallinity, Precipitation, Rice Fields Snail Shell

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: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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