Judul: Microscopic structure and functional structure of Seaweed Salt Ulva and Sargassum Polycystum
Abstrak: Rumput laut dapat dikembangkan menjadi garam fungsional yang memiliki manfaat salah satunya antihipertensi. Penelitian ini bertujuan untuk menentukan struktur mikroskopik dan gugus fungsi garam rumput laut dengan beberapa perbandingan konsentrasi residu rumput laut dari rumput laut dari Ulva lactuca dan Sargassum polycytsum. Tahapan penelitian meliputi preparasi sampel, pembuatan tepung dan garam rumput laut serta mengkarakterisasi fisik garam rumput laut. Garam rumput laut Ulva lactuca dan Sargassum polycystum mengandung kadar abu 41,05%, 27,50% dan kadar protein 7,33%, 7,04%. Hasil terbaik pada uji sensori adalah garam rumput laut Ulva lactuca 1:2 dan Sargassum polycystum 2:1. Hasil identifikasi mikroskopis Scanning Electron Microscope (SEM) menunjukkan perbesaran terbaik pada perbesaran 5000x dan Particle Size Analyzer (PSA) menunjukkan ukuran partikel signifikan terbaik 720,25±123,25 (nm) pada garam Ulva lactuca residu 1:2 dengan indeks keseragaman polidispersitas 0.68±0,17. Gugus fungsi yang terdeteksi hasil FTIR yaitu Hidroksil (OH), Medial alkkyne (C≡C), asam karboksilat asimetrik dan simetrik (C=C), amida III (C-N), alifatik berfluor dengan gugus fungsi C-F, aliphatic phosphates (P-O-C), menunjukkan gugus fungsi metal oxygen bonding, gugus fungsi C-H dan gugus fungsi aryl disulfides (S-S)., Seaweed can be developed into functional salts which have antihypertensive benefits. This study aims to determine the microscopic structure and functional groups of seaweed salt with several comparisons of concentrations of seaweed residues from seaweed from Ulva lactuca and Sargassum polycytsum. The stages of the research included sample preparation, manufacture of seaweed flour and salt and physical characterization of seaweed salt. Seaweed salt Ulva lactuca and Sargassum polycystum contain ash content of 41.05%, 27.50% and protein content of 7.33%, 7.04%. The best results in the sensory test were Ulva lactuca seaweed salt 1:2 and Sargassum polycystum 2:1. Microscopic identification of the Scanning Electron Microscope (SEM) showed the best magnification at 5000x magnification and the Particle Size Analyzer (PSA) showed the best significant particle size of 720.25 ± 123.25 (nm) in Ulva lactuca salt residue 1: 2 with a polydispersity uniformity index of 0.68 ± 0.17. The functional groups detected by the FTIR results were Hydroxyl (OH), Medial alkkyne (C≡C), asymmetric and symmetric carboxylic acids (C=C), amides III (C-N), fluorine aliphatic with C-F functional groups, aliphatic phosphates (P O-C), shows the metal oxygen bonding functional group, the C-H functional group and the aryl disulfides (S-S) functional group.
Keyword: FTIR, salt, PSA, seawead, sensory, SEM, PSA

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: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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