Judul: Synthesis and Characterization of Fluorapatite-Copper(II) Oxide with Sol-Gel Method as an Antibacterial Biomaterial
Abstrak: Fluorapatit (FAp) merupakan salah satu material kalsium fosfat yang berpotensi sebagai material antibakteri untuk pelapis implan gigi. Penelitian ini bertujuan menyintesis FAp pada tiga suhu pemasiran (600, 800, dan 1000 °C), tembaga(II) oksida (CuO), dan fluorapatit-tembaga(II) oksida (FAp-CuO) dengan metode sol-gel, serta menguji sifat antibakteri produk sintesis. Sintesis FAp melalui metode sol-gel telah berhasil dilakukan dan produk terbaik diperoleh pada suhu pemasiran 1000 °C (FAp 1000) berdasarkan nilai kristalinitasnya sebesar 90%. Hasil pencirian menggunakan difraktometer sinar-X (XRD), spektrometer inframerah transformasi Fourier, dan mikroskop elektron payaran-spektroskopi dispersif energi mengonfirmasi bahwa FAp 1000 merupakan fase dominan dengan nilai nisbah Ca/P dan P/F berturut-turut sebesar 1,84 dan 4,67. Produk CuO yang diperoleh juga merupakan fase dominan berdasarkan pola XRD. Penggantian ion Ca2+ oleh ion Cu2+ pada FAp-CuO terbukti mampu menurunkan nilai rerata ukuran kristal, kristalinitas, dan nisbah Ca/P. Tiga sampel uji (FAp, CuO, dan FAp-CuO) memiliki sifat antibakteri yang lemah terhadap Staphylococcus aureus dan Escherichia coli dengan rerata diameter zona hambat terbesar pada FAp-CuO, berturut-turut 0,243 dan 1,397 mm., Fluorapatite (FAp) is one of the calcium phosphate compounds that can be used as an antibacterial material for covering dental implants. This study aims to synthesize FAp at three sintering temperatures (600, 800, and 1000 °C), copper(II) oxide (CuO), and fluorapatite-copper(II) oxide (FAp-CuO) by sol-gel method, as well as test the antibacterial properties of synthetic products. Synthesis of FAp via the sol-gel process has been successfully carried out, and the best product is obtained at a sintering temperature of 1000 °C (FAp 1000) based on its crystallinity value of 90%. The characterization results using an X-ray diffractometer (XRD), Fourier-transform infrared spectrometer, and scanning electron microscope-energy dispersive spectroscopy confirmed that FAp 1000 was the dominant phase with Ca/P and P/F ratio values of 1,84 and 4,67; respectively. The CuO product formed is also the dominating phase according to the XRD pattern. Substituting Ca2+ ions with Cu2+ ions in FAp-CuO reduced the average crystal size, crystallinity, and Ca/P ratio. Three test samples (FAp, CuO, and FAp-CuO) had weak antibacterial properties against Staphylococcus aureus and Escherichia coli, with the largest average inhibitory zone diameter in FAp-CuO; 0,243 and 1,397 mm; respectively.
Keyword: antibakteri, fluorapatit-tembaga(II) oksida, pemasiran, sol-gel

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: Dynamics Model for Rural and Urban Economic Growth
Abstrak: Lewis theory of structural change has focused on mechanisms that allow countries to transform their domestic economic structure to a more modern economy. The proposed model deals with the mechanism of interaction between rural and urban Economic. This model is concerned with the process of labor transfer from rural to urban areas. This study aims to model the dynamics of economic growth in rural and urban areas, including determining the equilibrium solution and to carry out simulation of the model. The simulation results show that the transfer of labor from rural to urban areas will increase the rate of change of capital so that structural changes can be realized. In addition, increased propensity to save in rural areas will also accelerate structural change
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