Judul: Synthesis of Hydroxyapatite Nanoparticle from Tutut (Bellamyâ Javanica) Shells by Using precipitation and Hydrothermal Method
Abstrak: Biomaterials as bone replacement is a bioceramics of calcium phosphate-based known as hydroxyapatite (HAp) (Ca10(PO4)6(OH)2). Hap have the similar composition and crystallography of bone . In this study, synthesis of HAp by using precipitation and hydrothermal methods have been performed by using tutut shells (Bellamya Javanica). HAp of precipitation product contained 100 wt% of hydroxyapatite phase with Ca/P ratio of 1.71. The result of functional group analysis also showed the presence of hydroxyapatite phase as indicated by–OH, –PO4, dan –CO3 groups. HAp of wet precipitation product had lattice parameter of a = b = 9.418 Å, c = 6.885 Å. HAp of hydrothermal product contained 94.55 wt% of hydroxyapatite phase and 5.45 wt% of calcium oxide phase with Ca/P ratio of 2.03. The functional group analysis result showed peaks of –OH, –PO4, dan –CO3 groups, indicated the presence of hydroxyapatite phase. In addition to the peaks, the characteristic peaks of Ca–O and Ca–OH bond were also appear. HAp of hydrothermal product had lattice parameter of a = b = 9.4163 Å, c = 6.8791 Å. The synthesis of HAp nanoparticle both using precipitation and hydrothermal method have yielded. The HAp particles shaped spherical-polygonal with an average size of diameter particles around 10-20 nm. Whereas that by hydrothermal method is nanorod with the particle size of 15–20 nm in diameter and 40–60 nm in length.
Keyword: hydroxyapatite (HAp), hydrothermal, nanoparticle, wet precipitation, crystal structure

Judul: Sintesis Hidroksiapatit Berbasis Limbah Cangkang Keong Sawah (Bellamya javanica) dan Modifikasi Pori Menggunakan Gelatin
Abstrak: Hydroxyapatite is a ceramic material with a structure and composition similar to bone. In this study, hidroxyapatite was synthesized using shell of rice field snail as basic ingredients as a source of calcium (Ca(OH)2) and (NH4)2HPO4 as a source of phosphate. Synthesis method used was the wet method. In the synthesis process, porogen in the form of gelatin was added to increase the pore size. Concentrations of the added gelatin, were 20% and 30%. X-Ray diffraction results showed that the HAp phase has been formed with a fairly high purity. The best pores size resulted from the 30% gelatin concentration, was 0.5-3.98 μm. Infrared spectrum showed that the porogened and nonporogened Hap indicated functional group of HAp constituent
Keyword: shell of rice field snail., pore modification, hydroxyapatite, gelatin

Judul: Budget deficits, government debt and fiscal sustainability: application of vector error correction model
Abstrak: Buruknya kinerja deficit anggaran dan utang perintah sejak krisis ekonomi telah membuat kondisi fiscal menjadi unsustainab;e. Indikatornya, pemerintah tidak mampu membayar angsuran pokok utang dari sumber dananya sendiri melainkan dari penarikan pinjaman baru. Pemerintah cenderung membiarkan saja defisit terjadi dan membiayainya melalui pinjaman baru. Hal ini membuat ketergantungan deficit utang menjadi sangat tinggi. Sehingga untuk mengatasinya, pada saat yang sama harus mengatasi utang dan sebaliknya. Seandainya tingkat ketergantungan kedua variable tersebut tidak setinggi kenyataannya, upaya mengatasi kedua masalah tersebut akan jauh lebih mudah.
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