Judul: Potensi dan Karakteristik Natrium Alginat Padina australis pada Kondisi Lingkungan Perairan yang Berbeda di Kabupaten Sumbawa
Abstrak: Alginate is the main content of the cell wall of brown algae and is mainly consisted of β-D mannuronic acid and α-L guluronic acid units. Extracts of alginate play a key role in food industries, textiles, health and cosmetics. In food industry, alginates are used to stabilize mixtures dispersions and emulsions, which increase viscosity and forms gel, such as jam and jellies. Alginates can be used in the manufacture of soft capsules and consumed as a beverage for lowering blood sugar level. In the textile industry, alginate is used as an additive for textile dye. Padina australis is one of brown algae which mostly found in Sumbawa coastal waters. This species has potential as a raw material for alginate production. Differences in P. australis habitat may influence the alginate content as weel as characteristics. Several studies have shown that biomass and alginate content of brown algae are different on temporal and spatial scale. Spatial and temporal variations of biomass and alginate content are determined by differences in several physical and biological factors. Information and studies about the enviromental factor affecting biomass and alginate content of brown seaweed is rarely performed. Therefore, this study aims to determine the physical chemical parameters and location are appropriate for life and alginate content of Padina australis. Data were collected in the period between October 2012 to February 2013. Transect square method and visual observation was applied to determine condition of P. australis. Water parameters were analyzed in situ and in laboratory. Data analysis using analysis of varians (ANOVA) and Pearson correlation were performed. The result shows that biomass and alginate content of Padina australis is significantly influenced by interaction of physical and chemical enviromental factor. Padina australis grew in station 1 on October had the highest biomass and alginate content with characteristics of physical and chemical enviromental were hard substrate, current 0,40 m s-1, nitrate 1,5 μg.At/l, nitrite 0,06 μg.At/l, ammonia 0,27 μg.At /l, phosphorus 0,21 μg.At /l, pH 8, temperature 32 °C and salinity 32 psu. Ash content of alginate (38,48 – 41,76%) of Padina australis at all three stations were high considered, the value of viscosity (25 – 153 cps) is low viscosity, gel strength (7,30 – 19,33 g/cm2) is categorized as low and no detectable presence of Pb contents.
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Judul: Kajian penggunaan NaOCl dan kaporit pada pemucatan natrium alginat dari rumput laut cokelat (Sargassus polycystum)
Abstrak: Seaweed which is commonly found is mainly from red algae, green algae, and brown algae. Unfortunately, the utilization of seaweed in Indonesia has not been deeply explored. One product that can be obtained from seaweed extraction is alginate. Alginate can be extracted from Alginophyt plant, a group of brown seaweed (Phaeophyceae). Seaweed from brown algae contains approximately 20% of alginate. This compound is the main component of brown algae's cell wall and can be commercialized as gel, filler, stabilizer, emulsifier as well as basic ingredient in food processing, pain industry, pharmacy, and as explosive material. Sodium alginate is water soluble and has high commodity value. Based on Food grade and Pharmaceutical grade, degree of whiteness is one of the most important factors to determine the quality of sodium alginate.
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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. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular