Judul: Pelapisan Komposit Hidroksiapatit-gelatin pada Paduan Logam CoCrMo dengan Metode Dip Coating yang Dimodifikasi
Abstrak: Hidroksiapatit (HAp) dengan rumus kimia Ca10(PO4)6(OH)2 merupakan salah satu senyawa anorganik penyusun jaringan keras pada tubuh manusia seperti tulang dan gigi. Tujuan penelitian ini adalah menyintesis HAp dari cangkang keong sawah yang dikompositkan dengan gelatin dan melapisinya pada permukaan paduan CoCrMo dengan metode dip coating yang dimodifikasi untuk meningkatkan bioaktivitas kerekatan antara logam dan HAp. Kadar Ca yang terkandung dalam sampel CaO sebesar 44.73%. Analisis pola difraksi menggunakan difraksi sinar-X menunjukkan adanya fase HAp. Pelapisan komposit HAp-gelatin pada paduan CoCrMo dilakukan dengan ragam waktu perendaman, 6, 12 dan 24 jam. Konsentrasi gelatin yang ditambahkan adalah 1%, 2% dan 3%. Berdasarkan hasil analisis morfologi pelapisan terbaik dihasilkan pada waktu perendaman selama 24 jam dengan tambahan gelatin 3%. Hasil pengukuran pelepasan ion Ca2+ menunjukkan bahwa tambahan gelatin dapat meningkatkan bioaktivitas kerekatan antara HAp dan loga
Keyword: CoCrMo, modified dip coating method, gelatin, hydroxyapatite

Judul: Hydroxyapatite coating on metal alloys CoCrMo-TiN with Sol-Gel method
Abstrak: Hidroksiapatit (HAp) disintesis dengan metode presipitasi-sonikasi menggunakan sumber kalsium dari serbuk cangkang keong sawah dan sumber fosforus dari (NH4)2HPO4. Kadar kalsium diukur menggunakan spektofotometer serapan atom sebesar 82.82%. Suhu diragamkan pada 600, 800, dan 1000 oC untuk menentukan suhu terbaik pelapisan. Suhu terbaik tersebut digunakan untuk melapiskan HAp pada paduan logam CoCrMo-TiN menggunakan metode sol-gel termodifikasi. Lapisan yang menempel pada paduan logam diidentifikasi dengan diffraksi sinar X (XRD) dan uji korosi. Hasil XRD menunjukkan sebagian besar permukaan paduan logam CoCrMo-TiN terlapisi oleh HAp. Selain HAp, terdapat fase lain seperti kalsium fosfat, apatit karbonat tipe A dan tipe B. Hasil uji korosi paling baik ditunjukkan pada paduan logam CoCrMo-TiN yang terlapisi HAp dengan laju korosi paling kecil, yaitu 0.0082 mpy., Hydroxyapatite is synthesized by precipitation-sonification using calcium from field snail shell powder phosphorus from (NH4)2HPO4. The calcium level measured by atomic absorption spectrophotometer was 82.82%. The temperatures were varied on 600, 800, and 1000 oC to determine the best temperature of the coating. The best temperature was used to superimpose the HAp on the CoCrMo-TiN metal alloy using the modified sol-gel method. The layer on the metal alloy was identified with x-ray diffraction (XRD) and corrosion test. The XRD result showed that most of the CoCrMo-TiN metal alloy surface was coated by HAp. Beside HAp, there were several other phases such as calcium phosphate, carbonate apatite type A and type B. The best result of the corrosion test was showed in CoCrMo-TiN metal alloy coated with HAp with the smallest corrosion rate 0.0082 mpy. Key words: hydroxyapatite, metal alloys CoCrMo-TiN, precipitation-sonification, sol-gel modified
Keyword: hidroksiapatit, paduan logam CoCrMo-TiN, presipitasi-sonikasi, sol-gel termodifikasi

Judul: As partial requirement fulfilment for the Doctorate Degree in plant taxonomy
Abstrak: An account of the diversity, distribution, and taxonomy of the Asteraceae in Sumatera is given, There are 133 species of74 genera in 11 tribes, New species are recoqnized in this study, Prenanthes L. (2 species), Senecio L. (1 species), and Emilia sonchifolia (L.) DC (1 variety). The tribe Heliantheae is the largest, with 28% ofthe total number ofthe genera, followed by Astereae with 15%, Inuleae 12%, Senecioneae 10%, Anthemideae, Eupatorieae and Lactuceae 8%, the' other tribes are represented by 4% or less, The most diverse genus is Blumea DC with 14 species. Other genera are only represented by 10 species or less, usually 3, or 2, or, more usually, by 1 species only. In terms ofindigenous and endemic species, Sumatera is richer than Java, There are 43 important weed species, which were introduced from tropical America, Africa, Asia and Europe. Among these Chromolaena odorata (L.) RM. King & H Rob. and Mikania micrantha Kunth are reported as the most noxious ones. Studies on 9 species of Vernonia Schreb, in Sumatera were conducted to find distinct characters to support their taxonomic delimitation. Foliar trichome types may have taxonomical value to delimit sections. However, further study on many more specimens form larger geographical areas such as Malesia is required combined with other investigations, i.e. chemotaxonomy, pollen morphology or DNA analyses to obtain a better idea for new proposals of redefinitions of the sections.
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