Judul: Sintesis Nanopartikel Karbon Dot dan Grafena Oksida Tereduksi dari Jelaga Kerosen
Abstrak: Jelaga merupakan produk samping dari proses pembakaran yang berbahaya bagi lingkungan. Kandungan karbon yang tinggi pada emisi jelaga berpotensi sebagai bahan awal pembuatan nanopartikel, seperti grafena oksida tereduksi (rGO) dan karbon dot (C-dot). Penelitian ini bertujuan menyintesis rGO dan C-dot dengan metode sonikasi oksidasi asam dan tanpa oksidasi asam, serta metode gelombang mikro dan refluks dari jelaga kerosen. Hasilnya dibandingkan menggunakan spektrometer sinar ultraviolet-tampak (UV-Vis), inframerah transformasi Fourier, Raman, dan fluoresensi hibrid. Spektrum UV-Vis grafena oksida (GO) menunjukkan bahwa hasil metode sonikasi tanpa oksidasi asam memiliki puncak yang lebih tajam dan sempit dibandingkan dengan oksidasi asam. Spektrum raman menunjukkan bahwa GO berhasil direduksi dengan iradiasi gelombang mikro, tetapi masih berbentuk banyak lapisan dengan nisbah intensitas puncak D terhadap G sebesar 0,82. Presentasi puncak G yang lebih besar dari pada D menunjukkan perbaikan struktur dari sp3 ke sp2. Hasil sintesis karbondot (C-dot) berhasil dilakukan dengan metode refluks dengan pendaran berwarna biru kehijauan. Kata kunci: grafena, jelaga, gelombang mikro, karbondot, Soot is a by-product of the combustion process that harms the environment. The high carbon content in soot emissions has the potential to be a starting material for making nanoparticles such as reduced graphene oxide (rGO) and carbon dots (C-dot). This research aims to synthesize rGO and C-dot using and without acid oxidation, sonication methods, and microwave and reflux methods from kerosene soot. The results were compared using ultraviolet-visible light (UV-Vis), Fourier transform infrared spectroscopy, Raman, and hybrid fluorescence spectroneters. The UV-Vis spectrum of graphene oxide (GO) showed that the results of the sonication method without acid oxidation have sharper and narrower peaks compared to acid oxidation. The Raman spectrum exhibited that GO was successfully reduced by microwave irradiation, but it still forms many layers with a peak intensity ratio of D to G of 0.82. The presentation of peak G, which is more significant than D, indicates an improvement in the structure from sp3 to sp2. The carbon dot (C-dot) was successfully synthesized using the reflux method with a greenish-blue glow. Key words: carbon dots, graphene, microwave, soot
Keyword: carbon dots, graphene, microwave, soot

Judul: Sintesis Nanopartikel Karbon Berfluoresens dari Jelaga Kerosen dan Fine Coal
Abstrak: Carbon nanoparticles (C-dot) are among the materials which have fluorescence ability. C-dot can be synthesized from various materials with high carbon composition. The purposes of this research were to synthesize and characterize C-dot from kerosene soot and fine coal. C-dot was synthesized using the acid oxidation method with HNO3 as an oxidizing agent. The synthesized of Cdot has been conducted successfully with verification through out visual analysis, UV-Vis, fluorescence, and FTIR. The results showed that C-dot luminescence under 336 nm ultraviolet lamp increased with increasing concentrations of C-dot from both sources at 100, 250, 500, and 1000 ppm. UV-Vis measurement showed new absorption peaks indicating electronic transition from π→π* at 234 nm for Cdot from kerosene soot and 245 nm for C-dot from fine coal. The maximum emission obtaining from fluorescent measurement was 521 nm for C-dot from kerosene soot and 516 nm for C-dot from fine coal. Infrared spectrum showed real differences between C-dot and the starting material which indicated the success of functionalization at C-dot surface.
Keyword: Bogor Agricultural University (IPB), kerosene soot, kerosene soot, fine coal, fluorescence, carbon nanoparticle

Judul: Query Expansion based on Bilingual Dictionary Using Conditional Probability
Abstrak: Query expansion is a technique that can be used to bridge vocabulary gaps between queries and documents in the collection. With query expansion, user will be helped to formulate queries well so that user will optimize the search result. In this study, the expansion term was resulted from the translation of bilingual dictionary. Subsequently, several terms of expansion were elected based on the closeness of its relationship with the original query. This research showed that conditional probability can be used to select expansion term in bilingual translation method query expansion. The result of 1000 documents was more than 97% relevan document can be retrieved by this system. The more expansion term used, the larger number relevan document was retrieved.
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