Judul: Synthesis of Carbon Nanoparticles (C-dots) from Natural Dye and Their Characteristics
Abstrak: Nanopartikel karbon (C-dots) merupakan salah satu hasil dari perkembangan nanoteknologi yang mulai dikembangkan pada tahun 2004. C-dots memiliki sifat dapat berfluoresens. C-dots berpotensi menggantikan nanopartikel lain, seperti quantum dots yang telah berkembang lebih dulu. C-dots memiliki aplikasi yang hampir sama dengan quantum dots namun tidak beracun, sehingga dapat diaplikasikan lebih luas di berbagai bidang kehidupan. C-dots dapat disintesis dari prekursor yang mengandung karbon. Kualitas C-dots dapat ditingkatkan dengan sumber karbon senyawa organik yang memiliki sistem konjugasi serta mengandung heteroatom, salah satunya senyawa pewarna alami. Metode sintesis C-dots memberikan pengaruh terhadap kualitas C-dots hasil sintesis. Penelitian ini bertujuan mengkaji pustaka mengenai sintesis C-dots dari prekursor pewarna alami tumbuhan dan pengaruh metode sintesis serta prekursor heteroatom doping terhadap C-dots dari pewarna alami tumbuhan. Hasil menunjukkan C-dots yang disintesis dari tanin memiliki kualitas yang lebih baik dibandingkan dengan senyawa pewarna lainnya. Metode solvotermal meningkatkan kualitas C-dots dari gugus fungsi pelarutnya. Doping heteroatom nitrogen dapat menggunakan etilendiamina (EDA) dan urea sebagai sumber nitrogen. EDA meningkatkan panjang gelombang emisi, sedangkan urea meningkatkan quantum yield (QY) fluoresensi., Carbon nanoparticles (C-dots) are one of the results of the development of nanotechnology that began to study in 2004. C-dots have the property of being able to fluorescent. C-dots have the potential to replace other nanoparticles, such as quantum dots that have found earlier. C-dots had the same applications as quantum dots but not toxic so that they can be applied more widely in various sectors. C-dots can synthesize from a carbon-based precursor. The quality of C-dots can enhance with carbon-based organic compounds that have conjugated systems and contain heteroatoms, one of which is a natural dye compound. The synthesized method can influence the properties of C-dots. The research reviewed the literature on the synthesis of C-dot from natural plant dye precursors and the effect of synthesis methods and heteroatom doping precursors on C-dot from natural plant dyes. The results showed that the C-dots synthesized from tannin had better quality than other dye compounds. The solvothermal method improves the quality of C-dots from functional groups of solvent. Doping nitrogen can use ethylenediamine (EDA) and urea as nitrogen sources. EDA increases emission wavelength, while urea increases quantum yield (QY) of fluorescence.
Keyword: C-dots, emission, heteroatom doping, natural dye, quantum yield

Judul: Synthesis of fluorescent carbon nanoparticle
Abstrak: Nanopartikel karbon (C-dot) merupakan material yang termasuk ke dalam kelas nanopartikel 0 dimensi. C-dot dapat disintesis dari beberapa jenis asam organik yang berperan sebagai sumber karbon dan urea sebagai agen pasivasi permukaan C-dot. C-dot disintesis menggunakan metode oven mikrogelombang. Tujuan penelitian ini ialah menyintesis dan mencirikan C-dot dari beragam asam organik, yaitu asam askorbat, asam sitrat, dan asam oksalat dan beragam kadar urea yang ditambahkan. Kadar urea yang ditambahkan masing-masing 0, 10, 25, 50, dan 75% (b/b). Hasil yang diperoleh menunjukkan pendaran C-dot di bawah lampu ultraviolet 366 nm semakin meningkat dengan meningkatnya kadar urea. Emisi yang dihasilkan dari C-dot ini berada pada panjang gelombang 500 nm. Spektrum inframerah kadar urea yang beragam tidak menunjukkan perbedaan gugus fungsi yang nyata. Ukuran diameter rata-rata C-dot yang diperoleh sebesar ±18 nm. Uji kemampuan sensor C-dot yang dipreparasi dari asam askorbat dan urea 75% menunjukkan selektif terhadap ion logam Cr6+., Carbon nanoparticle (C-dot) is a material which belongs to the class of 0- dimensional nanoparticle. C-dot can be synthesized from several types of organic acid as a carbon source and urea as a passivation agent on the C-dot surface. C-dot was synthesized using microwave method. The purpose of this study was to synthesize and to characterize the C-dot from various organic acids, namely ascorbic acid, citric acid, and oxalic acid and various levels of added urea. The levels of aded urea were 0, 10, 25, 50, and 75% (w/w). The results showed the Cdot luminescence under ultraviolet light 366 nm increased with the increasing levels of urea. An emission resulting from the C-dot is located at a wavelength of 500 nm. Infrared spectra measurements of urea levels showed there was no significant differences in functional groups. The average diameter size of the Cdot was ±18 nm. The ability test toward heavy metal ion of the C-dot prepared using ascorbic acid and urea 75% showed selective toward Cr6+ ion. Key words: ascorbic acid, citric acid, carbon nanoparticle, fluorescence
Keyword: asam askorbat, asam sitrat, C-dot, fluoresens

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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