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: Variabilitas Transpor Arlindo Laut Flores dan Kaitannya dengan ENSO
Abstrak: Air Arlindo yang masuk ke Indonesia sebagian besarnya dilewatkan Laut Flores. Variasi volume transport Arlindo dipengaruhi oleh fenomena anomali iklim interannual seperti El Nino Southern Oscillation (ENSO). Hasil studi terdahulu menyimpulkan terjadinya La Nina meningkatan jumlah transport Arlindo, sedangkan El Nino melemahkan transport Arlindo. Untuk memahami lebih lanjut keterkaitan ENSO dengan variabilitas transport Arlindo dilakukanlah penelitian menggunakan data hasil model INDESO dan hasil observasi satelit dengan rentang waktu 2008 hingga 2015. Penelitian dilakukan di Laut Flores dengan mengkaji bagian barat (119.5oBT) dan bagian timur (123oBT) untuk melihat volume Arlindo yang masuk ke dan keluar dari Laut Flores. Analisis sirkulasi dilakukan dengan menghitung rataan komponen arus dan suhu permukaan laut secara tahunan dan pada rentang tahun ENSO untuk melihat pola sirkulasi perairan. Estimasi volume transpor dihitung dari transek di pintu barat dan pintu timur. Deret waktu volume transpor Arlindo Flores kemudian dianalisis variabilitasnya dengan analisis penapisan lolos-pita(band-pass filter) dan transformasi wavelet sinambung (Continous Wavelet Transform). Hasil penting studi ini menunjukkan bahwa sumber utama Arlindo Flores berasal dari pembelokan Arlindo Makassar dan Arlindo pintu timur Indonesia yang masuk melalui terusan Lifamatola. Kecepatan Arlindo Flores di lapisan tercampur menguat pada musim barat sebaliknya di lapisan termoklin Arlindo Flores menguat pada musim timur. Sumbu utama Arlindo Flores didominasi oleh komponen arus zonal serta mengalami intensifikasi dan bergerak menyusur bagian utara Kepulauan Nusa Tenggara. Fluktuasi Arlindo Flores pada skala-waktu interannual menunjukkan volume transport maksimum terjadi pada tahun La Nina (November 2008-Maret 2009), sedangkan volume transpor minimum terjadi pada tahun El Nino (November 2014-Desember 2015). Struktur menegak Arlindo lebih kuat di kedalaman antara permukaan sampai 400 m. Variabilitas Arlindo Flores menandakan adanya fluktuasi pada periode intraseasonal, semi-annual, dan annual. Fluktuasi Arlindo skala interannual muncul jelas dari hasil penapisan lolos-pita, dimana fluktuasinya terlihat signifikan di kedalaman termoklin.
Keyword: Arus Lintas Indonesia, Laut Flores, ENSO, INDESO model, variabilitas volume transpor