Judul: Characterization of Physicochemical Properties of Nanocalcium Extracted from Tilapia (Oreochromis niloticus) Bone
Abstrak: The utilization of fish bone as minerals source such as calcium and phosphorus is an effort to increase the economic value of waste fish bones. Calcium and phosphorus are essential compounds which play an important role in metabolic processes as well as health benefits. Generally, calcium is available in micro size, which is absorbed in the metabolic system at 50% of total calcium intake then the best alternative to improve absorption is reducing the size in nano (nm) so become nanocalcium, by milling process. The research aimed to perform the extraction of nanocalcium from tilapia (Oreochromis niloticus) bones by using different types of solvents, followed by milling process and study the characterization of physicochemical changes. The research was conducted in three main phases: 1) raw material preparation, 2) the extraction of nanocalcium from fish bones and 3) characterization of physicochemical nanocalcium sample. There are some process stages to prepare raw material: washing, boiling, drying and size reduction, then performed extraction to soften and change the bone structure to be milled easily. The extractions were done as follow: water (sample A), NaOH (sample B), NaOH followed by HCl (sample C) and HCl (sample D) which is followed by milling process to become nanocalsium before characterized, using raw materials (sample BB) as a control. Physicochemical characteristics that observed are include yield, whiteness degree, particle size, proximate, calcium and phosphorus, functional groups, morphology surface and crystal structure of the sample. Physicochemical analyzed that sample C is the sample with best character because has smaller particle size (145.50 nm) and the whiteness degree (93.72%) close to commercial standards of whiteness calcium as well as low of moisture, protein and fat content while ash, calcium and phosphorus content are high with ratio of Ca/P = 1.87. Calcium obtained is close to the hydroxyapatite characteristic so aplicate it in food has good properties mainly related to its solubility and bioavailability. Absorption peaks of sample revealed by FTIR (Fourier Transform Infrared) identified that phosphate (PO4 3-) group indicated as the symmetric bending, symmetric stretching, asymmetric stretching, and asymmetric bending vibrations. Absorption band of carbonate (CO3 2-) group indicated the apatite carbonate type A and B. Morphological analysis using SEM (Scanning Electron Microscopy) showed that surface of sample is change as result of the extraction process and the type of used solvent. Extraction using acid solution made sample becomes more porous and sharper, while extraction using alkaline solution made sample surface flatter, while extraction using water did not change the surface morphology of tilapia bone powder. The result of EDS (Energy Dispersive X-ray Spectroscopy) analysis showed that sample consist of 4 main elements such as carbon (C), oxygen (O), phosphorus (P) and calcium (Ca). The type of solvent affects the mass percent of there elements. Extraction using acid solution was increased mass percent of phosphorus and decreased mass percent of carbon and calcium. XRD (X-Ray Diffraction) analysis showed crystalline phase in the sample form carbonate apatite either type A or B and hydroxyapatite [Ca5(PO4)3(OH)]. Samples performed crystalline
Keyword: 

Judul: Pengaruh Konsentrasi NaOH terhadap Karakteristik Tepung Tulang Ikan Sidat (Anguilla bicolor bicolor) Sebagai Sumber Kalsium
Abstrak: Industri pengolahan hasil perikanan menyisakan hasil samping berupa kepala, ekor, sirip, tulang dan jeroan ikan. Ikan sidat banyak dimanfaatkan menjadi kabayaki, sehingga bagian tubuh lainnya, termasuk tulang, tidak dimanfaatkan. Limbah tulang ikan sidat memiliki potensi untuk dimanfaatkan sebagai sumber kalsium untuk manusia. Penelitian ini bertujuan untuk menentukan pengaruh konsentrasi NaOH (0,5 N; 1 N; 1,5 N) terhadap sifat fisik dan kimia kalsium dari tulang ikan sidat yang dihasilkan melalui proses ekstraksi menggunakan NaOH, pengeringan dan kalsinasi pada suhu 600 °C. Hasil penelitian menunjukkan kadar kalsium tepung berkisar 29%, kadar fosfor 10%, kadar abu tak larut asam yang rendah 0,05–0,19% yang menunjukkan bahwa tepung tulang ikan mengandung bahan pengotor yang rendah. Nilai derajat putih tepung tergolong baik dengan kenampakan berwarna putih keabuan dan rendemen tertinggi 20%. Partikel tepung tulang ikan yang dihasilkan mengandung gugus fungsi PO43- dan CO32- dengan bentuk pulver berdasarkan hasil analisis SEM pada perbesaran 20.000x. Hasil penelitian menunjukkan tepung tulang ikan sidat yang dihasilkan dipengaruhi oleh konsentrasi NaOH yang digunakan., The fishery product processing industry in each production leaves byproducts in the form of heads, tails, fins, bones and fish offal. Fish bone is one of the fishery industry wastes that have wide potential to be developed because it contains important minerals. Eel fish is widely used as kabayaki, so other body parts such as bone is not used properly. This study aimed to determine the effect of NaOH concentration on the physical and chemical properties of calcium from eel bones produced through the extraction process using NaOH, drying and calcining at 600 °C. The results showed that calcium flour content ranged from 29%, phosphorus content was 10%. The degree value of flour white was classified as good with a grayish-white appearance with the highest yield of 20%. This fishbone meal contained PO43- and CO32- functional group with a pulverized shape based on the result of SEM analysis at a magnification of 20.000x. Based on the results of this study, eel fish bone meal affected by the concentration of NaOH.
Keyword: calcium, eel, fish bone meal

Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh.
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. ,,,
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular.