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: Kajian Struktur dan Morfologi Hidroksiapatit yang Disintesis Menggunakan Metode Hidrotermal
Abstrak: Hydroxyapatite is a material that can be bonded to the building blocks of bone. In this study has been carried out the synthesis of hydroxyapatite using hydrothermal method. Precursor calcium is derived from leghorn chicken eggshell as well as to the source of phosphate using (NH4)2HPO4. In the hydrothermal method to various temperatures of 150 oC, 200 oC, 250 oC, and 300 oC at 3 hours and variations in time of 1 hour and 5 hours at a temperature of 150 oC. Phase and crystal structure of hydroxyapatite were analyzed using X-ray diffractometer (XRD). While the morphology of hydroxyapatite imaged using scanning electron microscopy (SEM). The samples were synthesized using hydrothermal method has formed hydroxyapatite phase. Hydroxyapatite synthesized by hydrothermal method have a value close to the lattice parameter of data JCPDS. XRD characterization results on the various temperatures and hydrothermal time of the 6 samples such as 150 oC, 200 oC, 250 oC, 300 oC for 3 hours and 150 oC at 1 hour, 3 hours, and 5 hours showed that the optimum phase HAp formed it a sample temperature of 150 oC time 3 hours is equal to 98.6% which an efficiency is 45.6%, 78.028 nm crystal size, and degree of crystallinity of 83.4%. Test result by SEM showed that formation of space between microsized HAp particles were clearly visible on the sample. Space of this size is about 2.1 μm.
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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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