Judul: Pengaruh Jenis Rumput Laut Hijau (Ulva lactuca dan Chaetomorpha sp) terhadap Karakteristik Garam Rumput Laut.
Abstrak: Rumput laut hijau Ulva lactuca dan Chaetomorpha sp. yang terdapat di Indonesia dapat dimanfaatkan sebagai sumber bahan baku pembuatan garam rumput laut. Tujuan penelitian ini untuk menentukan pengaruh rumput laut hijau U. lactuca dan Chaetomorpha sp. terhadap karakteristik garam rumput laut yang memiliki kadar NaCl <60%, rasio Na:K yang rendah, dan aktivitas antioksidan yang tinggi. Garam rumput laut dihasilkan dari filtrat ekstraksi tepung rumput laut dengan pelarut akuades konsentrasi 1:10, dan dipanaskan dalam water bath suhu 40ºC selama 10 menit dan dikeringkan menggunakan oven suhu 60ºC selama 48 jam. Garam U. lactuca menghasilkan rendemen 23,67%, rasio Na:K 1,74, NaCl 57,36%, dan total fenol 466,13 mg GAE/g, serta aktivitas antioksidan (ABTS) 147,54 ppm, dan (CUPRAC) 40,04 µmol/g. Garam Chaetomorpha sp. menghasilkan rendemen 17,33%, rasio Na:K 1,63, NaCl 61,45%, dan total fenol 677,78 mg GAE/g, serta memiliki aktivitas antioksidan (ABTS) 95,40 ppm, dan (CUPRAC) 59,20 µmol/g garam., Green seaweed Ulva lactuca and Chaetomorpha sp. found in Indonesia can be used as a source of raw material for making seaweed salt. The purpose of this study was to determine the effect of green seaweeds Chaetomorpha sp. and U. lactuca on the characteristics of seaweed salt which has <60% NaCl level, low Na:K ratio, and high antioxidant activity. Seaweed salt is produced from seaweed flour extraction filtrate with distilled water with a concentration of 1:10, and heated in a water bath at 40°C for 10 minutes and dried using an oven at 60°C for 48 hours. U. lactuca salt produces a yield of 23.67%, Na:K ratio 1.74, NaCl 57.36%, and total phenol 466.13 mg GAE/g, and antioxidant activity (ABTS) 147.54 ppm, and (CUPRAC) 40.04 µmol/g. Chaetomorpha sp. salt produces a yield of 17.33%, Na:K ratio 1.63, NaCl 61.45%, and total phenol 677.78 mg GAE/g, and has antioxidant activity (ABTS) 95.40 ppm, and (CUPRAC ) 59.20 µmol/g salt.
Keyword: antioxidant, Chaetomorpha sp., seaweed salt, Ulva lactuca

Judul: Antioxidant Activity and Characteristics of Ulva lactuca Combination Salt, Antioxidant Activity and Characteristics of Ulva lactuca Combination Salt
Abstrak: Rumput laut hijau Ulva lactuca dapat dimanfaatkan sebagai sumber bahan baku garam rumput laut yang memiliki aktivitas antioksidan. Penelitian ini bertujuan menentukan kombinasi filtrat dan residu terbaik garam rumput laut yang memiliki karakteristik sesuai dengan standar mutu garam konsumsi yang dianjurkan untuk pasien hipertensi. Garam rumput laut diperoleh dari filtrat ekstraksi tepung Ulva lactuca dengan pelarut akuades rasio 1:10. Garam dari filtrat murni (K) yang diperoleh ditambahkan residu dengan rasio garam filtrat dan residu 1:1 (A), 1:2 (B), dan 2:1 (C). Garam yang dihasilkan dilakukan uji komposisi mineral, kontaminan logam berat, rasio Na:K, kadar NaCl, kadar serat pangan, kadar iodium (KIO3), uji sensori garam, dan uji antioksidan. Garam K memiliki rasio Na:K 1,45, kadar NaCl 17,87%, dan residu logam berat di bawah standar maksimum SNI garam diet. Kadar serat pangan tertinggi dihasilkan pada garam B sebesar 35,63%. Aktivitas antioksidan menggunakan metode uji ABTS diperoleh nilai tertinggi pada garam C sebesar 55,07 ppm dan kapasitas antioksidan dengan metode uji CUPRAC diperoleh nilai tertinggi pada garam filtrat sebesar 21,57 μmol trolox/g., Ulva lactuca green seaweed can be used as raw material source for seaweed salt which has antioxidant activity. This study aims determine the best combination of filtrate and residue of seaweed salt which has characteristics in accordance with the standard of consumption salt quality which recommended for hypertensive patients. Seaweed salt was obtained from the extraction filtrate of Ulva lactuca flour with a 1:10 ratio of distilled water as a solvent. The salt from the pure filtrate (K) obtained was added to the residue with the ratio of the filtrate salt to the residue of 1:1 (A), 1:2 (B), and 2:1 (C). The resulting salt was tested for mineral composition, heavy metal contaminants, Na: K ratio, NaCl content, dietary fiber content, iodine content (KIO3), salt sensory test, and antioxidant test. The salt K has a Na: K ratio of 1.45, NaCl content of 17.87%, and heavy metal residues below the SNI maximum standard for dietary salt. The highest content of dietary fiber was produced in salt B of 35.63%. The antioxidant activity using the ABTS test method obtained the highest value for the C salt of 55.07 ppm and the antioxidant capacity with the CUPRAC test method obtained the highest value for the filtrate salt of 21.57 μmol trolox/g.
Keyword: antioxidants, NaCl, Na: K ratio, Ulva lactuca, seaweed salt

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model