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Abstrak :
Penelitian ini merupakan rangkaian penelitian lanjutan dari studi iron removal pada sampel pregnant leach solution (PLS) hasil pelindian bijih nikel laterit. Penelitian ini berfokus pada pengendapan unsur nikel dan kobalt yang terkandung di dalam sampel dengan proses hidrometalrugi menjadi produk mixed hydroxide precipitate (MHP). Sebelumnya, sampel PLS sudah dilakukan penghilangan kadar besi dengan penambahan kalsium karbonat sebanyak 2 kali dengan kandungan 25% w/w dan 12,5% w/w yang dilakukan selama 2 jam dan 1 jam pada temperature 90oC. Hasil pengurangan besi yang dilakukan menunjukkan pengurangan kandungan besi dari sampel bijih PLS sebesar 75% dari kandungan semula yang sudah diuji dengan ICP. Selanjutnya penelitian dilanjutkan untuk memproduksi MHP dengan penambahan larutan NaOH sebesar 4M kedalam larutan PLS yang sudah dikurangi kandungan besinya dengan presipitasi sebelumnya. Presipitasi dengan NaOH dilakukan hingga mencapai pH 7 lalu dipanaskan hingga suhu 60oC selama 1 jam. Hasil penelitian yang dilakukan hingga pH 7 menunjukkan hasil yang belum optimal dengan kandungan nikel yang hanya sebesar 5% dari total kandungan setelah dilakukan proses pengurangan kadar besi yang kedua kali. Penelitian ini menemukan beberapa faktor yang mungkin menyebabkan tidak bertambahnya kadar nikel dalam produk MHP setelah dilakukan presipitasi dengan larutan NaOH. Tingkat viskositas yang terlalu tinggi selama titrasi, masih tingginya kadar pengotor yang terkandung dalam larutan pasca pengurangan besi, serta endapan yang tidak kristalin menjadi faktor yang membuat larutan lewat jenuh dan kurang optimalnya hasil pasca penelitian. Waktu penyimpanan larutan pasca titrasi juga menjadi faktor yang membuat kandungan nikel dan kobalt tereduksi dan pengotor tidak terikat sempurna. ......This research is a follow-up research series from the study of iron removal on pregnant leach solution (PLS) samples from the leaching of laterite nickel ore. This research focuses on the deposition of Nickel and Cobalt elements contained in the sample by a hydrometallurgical process to become a mixed hydroxide precipitate (MHP) product. Previously, the PLS sample had iron content removed with the addition of calcium carbonate 2 times with a content of 25% w/w and 12.5% ​​w/w for 2 hours and 1 hour at a temperature of 90oC. The results of the iron reduction carried out showed a reduction in the iron content of the PLS ore samples by 75% of the original content that had been tested with ICP. Furthermore, the research continued to produce MHP with the addition of 4M NaOH solution into the PLS solution which had been reduced in iron content by previous precipitation. Precipitation with NaOH was carried out until it reached pH 7 and then heated to a temperature of 60oC for 1 hour. The results of the research carried out up to pH 7 showed that the results were not optimal with the nickel content only 5% from all the contents after the second process of reducing the iron content was carried out. This study found several factors that might cause the nickel content to not increase in MHP products after precipitation with NaOH solution. Viscosity levels that are too high during titration, high levels of impurities contained in the solution after iron reduction, and non-crystalline precipitates are factors that make the solution supersaturated and post-test results are less than optimal. The storage time of the post-titration solution is also a factor that makes the reduced nickel and cobalt content and impurities not completely bound.

Abstrak :
Nanocomposites of zinc-aluminium-anthranilate (ZAAN) have been synthesized at different concentrations of anthranilic acid by co-precipitation method. These materials have been examined in detail by powder X-ray powder diffraction (PXRD) which showed the expansion of the basal spacing from 0.89 to ca. 1.33 nm and the shifting of the 003 peak towards the lower 2q angle. This indicates that the anthranilate anion was successfully intercalated into the interlayer gallery. However, FTIR analysis showed nitrate anion was also co-intercalated in the interlayer. The resulting nanocomposites show Type IV adsorption-desorption isotherms indicated the mesoporous structure of the material. BET surface area was found to be slightly different compared to zinc-aluminium-nitrate-layered double hydroxide (ZANO) after the intercalation process took place. Both ZANO and ZAAN have similar surface morphology, namely a flaky-like structure, but they are of different sizes.

Abstrak :
Indonesian Journal of Dentistry 2006; Edisi Khusus KPPIKG XIV: 111-116 Apexification is the preparation of the endodontic treatment for a tooth with pulpal necrosis and incomplete developed apex. The aim of this treatment is to stimulate further apex development and formation of calcified tissue at the apex, so that conventional endodontic treatment could be performed. One of the most suitable material for apexification is calcium hydroxide since it has an excellent biocompatibility, antimicrobial property, and ability to stimulate hard tissue formation. In this case, apexification was performed on a 9 years old boy with incompletely developed apex and necrosis 36 tooth. Thereis, no subjective or clinical symptoms after 6 months. Although in the radiograph, apical closure was not clearly detected, apical stop was obtained in clinical examination. Subsequently, the 36 tooth was restored with onlay.

Abstrak :
Fluorosis is a condition due to ingestion of excessive amounts of flour which can cause the change in tooth structure and strength. However, there is still lack of explanation on the surface structure of crystal hydroxyapatite that influences the microscopic characteristic of fluorosis enamel. Objectives: To investigate the surface structure of crystal hydroxy-apatite in fluorosis enamel. Materials and methods: Determination of fluor concentration and the surface structure of normal and fluorosis enamel specimen were carried out by using Scanning Electron Microscopy/ Energy Disperse X-Ray (SEM/ EDX). Results: Fluor concentration of fluorosis enamel was significantly higher with increased surface roughness and porosity than normal enamel. SEM observation also showed gaps areas between enamel rods and visible aprismatic zone in some regions. Conclusion: High level of fluor concentration on fluorosis enamel indicated the subtitution of OH- by F- increasing the surface roughness of enamel surface.

Abstrak :
Apexification is a procedure well recognized and accepted by clinicians and researchers alike. Apexification is an endodontic treatment that intends to stimulate of apex formation. One material in dentistry is calcium hydroxide that is most commonly used to induce an apical hard tissue barrier. Because of the capacity to promote enviromental condition for tissue repair, calcium hydroxide can be used in the management of most endodontic problem, such as pulp capping, pulpotomy, root canal treatment, apexification and various endodontic situations. Due to its high alkalinity is has an antibacterial effect, promotes mineralization, induces healing, and initiates hard tissue formation. Although there have been many reports on the subject, the mechanisms of action are still unknown.