Preparation Of Hydroxyapatite Powders For Medicalapplications Via Sol-gel Technique

PREPARATION OF HYDROXYAPATITE POWDERS FOR MEDICALAPPLICATIONS VIA SOL-GEL TECHNIQUE. Hydroxyapatite (HA) powders have been prepared via sol-gel procedure using calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate as the precursors for calcium and phosphorus, respectively. An ammoniacal solution of the monomers was heated at 100°C for about 3 –4 h until a white gel of hydroxyapatite mixture were obtained. The obtained gel was then dried at 340°C for 7 h and subsequently subjected to an 820°C calcination for 2 h. The yield of the powder mixture ranged between 50 to 53 g. XRD measurement shown that the powder contained hydroxyapatite crystal with b-TCP ( 15-20%) and calcium oxide (4-6%) as secondary phases. Further treatment was conducted to gain hydroxyapatite powder of higher purity, thus the correct Ca/P ratio, by adding an appropriate amount of di-ammonium hydrogen phosphate and heated while stirring at 90°C for 4 h. Good purity (almost 100%) of the obtained hydroxyapatite was confirmed by XRD analysis.This result proved that our HA powder meets the medical prerequisite: a HA purity of above 95%. Morphological evaluation by SEM measurement shows that the particles of the HA agglomerate are globular in shape with an average size of 1-2 mm in diameter. Meanwhile, the primary particles have a diameter of 70-150 nm in average. Surface area of the powder is 7 m2/g and the mean particle size as measured using X ray sedimentation method is ca. 1 mm. The measurements are not in good agreement with the morphological investigation. We consider, accordingly, that the particles presumably have high surface potentials, thus forming very tightly bonded agglomerate

Pengaruh Modifikasi Kristal Kalsium Atorvastatin terhadap Laju Disolusi

Kalsium atorvastatin merupakan salah satu obatanti-kolesterol yang memiliki bentuk kristal yangbanyak dan kelarutan yang kurang baik, denganbioavailabilitas yang hanya mendekati 14%. Penelitianmengenai pengaruh Perubahan bentuk kristal kalsiumatorvastatin terhadap profil disolusi bertujuan untukmengetahui terbentuk atau tidaknya kristal kalsiumatorvastatin bentuk lain setelah proses modifikasidan perbandingan profil disolusi berdasarkan hasiluji disolusi terbanding. Metode penelitian meliputimodifikasi kristal mengacu kepada jurnal EuropeanPatent dengan modifikasi pada suhu pemanasandan pendinginan, karakterisasi produk kristal yangterbentuk dengan menggunakan difraksi sinar xdan spektrofotometer infra merah, juga uji disolusiterbanding. Metode modifikasi kristal menghasilkankristal baru bentuk V. Hasil modifikasi kristal kalsiumatorvastatin menunjukkan kristal A adalah kalsiumatorvastatin tanpa modifikasi, kristal B dan C adalahkalsium atorvastatin modifikasi dengan pelarut etanoldan metanol. Hasil uji disolusi terbanding diperolehbahwa kristal B dan C melarut 16% dan 6,3% lebihbanyak dari kristal A pada 45 menit pada dapar fosfatpH 6,8, kristal B dan C melarut 14,55% dan 23,65%lebih banyak dari kristal A pada 45 menit pada daparasetat pH 4,5 kristal B dan C melarut 4,97% dan7,545% lebih banyak dari kristal A pada 45 menit padadapar asam klorida pH 1,2

Analisis Variasi Jarak Sumbu Poros Terhadap Tegangan Kontak Dan Tegangan Bending Pada Helical Gear Pair Berdasarkan Metode Elemen Hingga

This researchs object is determining  the effect of modifying center distance to bending stress and contact stress on the helical gear pair based on the finite element method. And to know the safety factor on each center distance variation within helical gear pair. Gear being analyzed is one of the gears on Honda motor cycles branded Beat. To know the specification of gear, the helical gear geometry measurements were taken. Based on the results of measurements was carried out models of helical gear pair by AUTO CAD software. Then,  bending stress and contact stress analysis with finite element method on  ANSYS 12.1. Optimal center distance of gear pairs is determined by safety factors on the quasi statatis condition. From the research results can be concluded that the change of center distance can affect the bending stress and contact stress on gears and affect of security design. A safe center distance variation is 52.65 mm, 52,75 mm, 52,85mm and 52.95 mm

PENGARUH PENGAWASAN KEUANGAN, AKUNTABILITAS DAN TRANSPARANSI PENGELOLAAN KEUANGAN TERHADAP KINERJA PEMERINTAH DAERAH (Survey pada Dinas di Pemerintah Kabupaten Bandung Barat)

ABSTRAK Penelitian ini bertujuan untuk mengetahui seberapa besar pengaruh pengawasan keuangan, akuntabilitas dan transparansi pengelolaan keuangan terhadap kinerja pemerintah daerah. Populasi pada penelitian ini adalah pada Team Anggaran di dinas-dinas Kabupaten Bandung Barat Jumlah sampel yang diambil sebanyak 40 responden. Metode penelitian yang digunakan adalah metode deskriptif dan verifikatif. Teknik pengumpulan data yang dilakukan melalui data primer dengan kuesioner. Teknik sampling menggunakan teknik Probability Sampling dengan menggunakan metode Simpel Random Sampling. Analisis statistik yang digunakan dalam penelitian ini yaitu uji validitas, uji reabilitas, analisis korelasi berganda, analisis regresi linier berganda, uji T, uji F, uji asumsi klasik, dan koefisien determinasi. Hasil penelitian menunjukan bahwa besarnya pengaruh pengawasan keuangan terhadap kinerja pemerintah daerah yaitu sebesar 9,5%. Pengaruh akuntabilitas pengelolaan keuangan terhadap kinerja pemerintah daerah memberikan pengaruh sebesar 22,5%. Pengaruh transparansi pengelolaan keuangan daerah terhadap kinerja pemerintah daerah memberikan pengaruh sebesar 29,0%. Secara simultan menunjukan bahwa besarnya pengaruh pengawasan keuangan, akuntabilitas dan transparansi pengelolaan keuangan terhadap kinerja pemerintah daerah sebesar 61,0% Sedangkan sisanya yaitu sebesar 39% dipengaruhi factor lain yang tidak diamati dalam penelitian ini. Dengan demikian, semakin tinggi pengaruh pengawasan keuangan, akuntabilitas dan transparansi pengelolaan keuangan maka akan semakin meningkatkan kinerja pemerintah daerah. Kata kunci : pengawasan keuangan, akuntabilitas pengelolaan keuangan, transparansi pengelolaan keuangan dan kinerja pemerintah daera

PENGARUH MODIFIKASI KRISTAL KALSIUM ATORVASTATIN TERHADAP LAJU DISOLUSI

Kalsium atorvastatin merupakan salah satu obatanti-kolesterol yang memiliki bentuk kristal yangbanyak dan kelarutan yang kurang baik, denganbioavailabilitas yang hanya mendekati 14%. Penelitianmengenai pengaruh perubahan bentuk kristal kalsiumatorvastatin terhadap profil disolusi bertujuan untukmengetahui terbentuk atau tidaknya kristal kalsiumatorvastatin bentuk lain setelah proses modifikasidan perbandingan profil disolusi berdasarkan hasiluji disolusi terbanding. Metode penelitian meliputimodifikasi kristal mengacu kepada jurnal EuropeanPatent dengan modifikasi pada suhu pemanasandan pendinginan, karakterisasi produk kristal yangterbentuk dengan menggunakan difraksi sinar xdan spektrofotometer infra merah, juga uji disolusiterbanding. Metode modifikasi kristal menghasilkankristal baru bentuk V. Hasil modifikasi kristal kalsiumatorvastatin menunjukkan kristal A adalah kalsiumatorvastatin tanpa modifikasi, kristal B dan C adalahkalsium atorvastatin modifikasi dengan pelarut etanoldan metanol. Hasil uji disolusi terbanding diperolehbahwa kristal B dan C melarut 16% dan 6,3% lebihbanyak dari kristal A pada 45 menit pada dapar fosfatpH 6,8, kristal B dan C melarut 14,55% dan 23,65%lebih banyak dari kristal A pada 45 menit pada daparasetat pH 4,5 kristal B dan C melarut 4,97% dan7,545% lebih banyak dari kristal A pada 45 menit padadapar asam klorida pH 1,2.Kata Kunci: Kalsium atorvastatin, difraksi sinar-x,disolusi, kristal, polimorfisme

Surface modification of polycaprolactone (PCL) microcarrier for performance improvement of human skin fibroblast cell culture

Polycaprolactone (PCL) has many advantages for use in biomedical engineering field. In the present work PCL microcarriers of 150-200 µm were fabricated using oil-in-water (o/w) emulsification coupled with solvent evaporation method. The surface charge of PCL microcarrier was then been improved by using ultraviolet/ozone treatment to introduce oxygen functional group. Immobilisation of gelatin onto PCL microspheres using zero-length crosslinker provides a stable protein-support complex, with no diffusional barrier which is ideal for mass processing. The optimum concentration of carboxyl group (COOH) absorbed on the surface was 1495.9 nmol/g and the amount of gelatin immobilized was 1797.3 µg/g on UV/O3 treated microcarriers as compared to the untreated (320 µg/g) microcarriers. The absorption of functional oxygen groups on the surface and the immobilized gelatin was confirmed with the attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and the enhancement of hydrophilicity of the surface was confirmed using water contact angle measurement which decreased (86.93o – 49.34o) after UV/O3 treatment and subsequently after immobilisation of gelatin. The attachment and growth kinetics for human skin fibroblast cell (HSFC) showed that adhesion occurred much more rapidly for gelatin immobilised surface as compared to untreated PCL and UV/O3 PCL microcarrier

Calcified Algae for Tissue Engineering.

This book presents the latest advances in marine structures and related biomaterials for applications in both soft- and hard-tissue engineering, as well as controlled drug delivery

THE EFFECTS OF EXCESS CALCIUM AND AGING MEDIA ON THE MECHANICAL PROPERTIES OF CALCIUM PHOSPHATE FILLING MATERIALS

The effect of excess calcium and aging media on calcium phosphate biomaterials mechanical strength was studied. The variation of excess calcium and sample type hasshown different performancewhen they are being aged in the moist environment (ME) and the simulated body fluid (SBF).The calcium phosphateswere synthesized via low temperature hydrothermal method and sampled to two types of powder-water (3:2)mixture and paste for 90 days of the aging time. Two mechanical tests were applied, compression and diametrical tensile test, while XRD to evaluate phases.Scanning electron micrograph showed the paste samples that soaked in SBF was better entanglement of the particles, bettercompressionstrength but with degradation and diametrical tensile strength improvement by aging. Calcium hydroxide and ammonium di-hydrogen phosphoric was traced in all the samples along with calcium deficient hydroxyapatite as the main phase