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.
Keyword: 

Judul: Meta-analysis the Effect of Temperature and  Extraction Method to Characteristics of Sodium Alginate from Seaweed  Sargassum sp.
Abstrak: Alginat merupakan hidrokoloid yang dihasilkan oleh Sargassum sp.. Kualitas natrium alginat dapat dipengaruhi oleh metode dan suhu ekstraksi. Tujuan penelitian ini menentukan pengaruh perbedaan metode (asam dan kalsium) dan suhu ekstraksi (40-50°C dan 60-70°C) terhadap karakteristik Na-alginat (rendemen, derajat putih, kadar abu, pH, viskositas, dan kadar air) dari Sargassum sp.. Penelitian dilakukan dengan metode meta-analysis berupa subgroup analysis, dan hasil ditampilkan dengan forest plot. Natrium alginat yang optimal dihasilkan oleh metode asam dan suhu 60-70°C. Metode asam menghasilkan derajat putih, kadar abu, pH, viskositas, dan kadar air lebih optimal, namun rendemen lebih rendah dari metode kalsium. Hasil rendemen, derajat putih, kadar abu, dan viskositas optimal pada suhu 60-70°C. Perbedaan metode menghasilkan perbedaan signifikan pada derajat putih dan viskositas, namun tidak berbeda signifikan pada nilai rendemen, kadar abu, pH, dan kadar air. Perbedaan suhu menghasilkan perbedaan signifikan pada nilai rendemen dan derajat putih, namun tidak berbeda signifikan pada kadar abu, pH, viskositas dan kadar air, Alginate is a hydrocolloid produced by Sargassum sp.. The quality of sodium alginate can be influenced by the method and extraction temperature. The purpose of this research was to study the effect of different methods (acid and calcium), and extraction temperatures (40-50°C and 60-70°C) on the characteristics of sodium alginate (yield, whiteness, ash, pH, viscosity, and water content) from Sargassum sp.. This study used subgroup analysis by meta-analysis. The results are shown by forest plot. The result showed that the optimal characteristics of sodium alginate are produced by the acid method and extraction temperature 60-70°C. The acid method produces more optimal whiteness, ash, pH, viscosity, and water content, but lower yield. Extraction temperatures 60- 70°C produces optimal results on yield, whiteness, ash, and viscosity. Different methods resulted in significant differences in the whiteness and viscosity, but did not significantly differ in the yield, ash, pH, and moisture content. Temperature difference resulted in a significant difference in the yield and whiteness, but did not give a significant difference in the ash, pH, viscosity, and water content.
Keyword: extraction, meta-analysis, Sargassum sp, sodium alginate

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