Judul: Ekstraksi Rumput Laut Coklat Padina sp. dan Pengujian Ekstrak sebagai Inhibitor Tirosinase
Abstrak: Pigmentasi kulit yang disebabkan oleh sinar matahari diprakarsai oleh suatu proses yang disebut melanogenesis. Proses melanogenesis dikatalisis oleh tirosinase. Penelitian ini bertujuan menentukan aktivitas inhibitor tirosinase dari ekstrak metanol Padina sp. dan menentukan komponen aktif yang terkandung dalam ekstrak metanol Padina sp. yang diambil dari Pantai Karimun Jawa, Jepara, Jawa Tengah. Ekstraksi dilakukan dengan maserasi dan menghasilkan rendemen sebesar 2,53±0,44%. Penentuan aktivitas inhibitor tirosinase menggunakan substrat L-tirosin dan L-DOPA. Hasil IC50 untuk masing-masing substrat berturut-turut adalah 34.32±6,54 μg/mL dan 30,32±4,55 μg/mL. Ekstrak Padina sp. positif mengandung alkaloid, flavonoid, komponen fenolik, steroid, triterpenoid, dan saponin yang diduga sebagai kelompok senyawa kimia yang berpotensi menjadi inhibitor tirosinase.
Keyword: ekstraksi, inhibitor tirosinase, Padina sp

Judul: Ekstraksi Rumput Laut Coklat Sargassum sp. (CP 02) dan Pengujian Ekstrak sebagai Inhibitor Tirosinase
Abstrak: Enzim tirosinase merupakan enzim yang berperan dalam pembentukan melanin. Zat yang dapat menghambat kerja enzim tirosinase disebut inhibitor tirosinase. Sargassum sp. merupakan salah satu jenis rumput laut coklat yang dapat berperan sebagai inhibitor tirosinase. Tujuan dari penelitian ini adalah menentukan rendemen ekstrak, menentukan aktivitas ekstrak dalam menghambat enzim tirosinase dan menentukan kelompok senyawa kimia yang terdapat pada ekstrak Sargassum sp. (CP 02). Hasil penelitian menunjukkan redemen ekstrak Sargassum sp. (CP 02) sebesar 2,37±0,66%, nilai IC50 pada reaksi monophenolase dengan substrat L-tirosin sebesar 13,43±1.45 μg/mL dan nilai IC50 pada reaksi diphenolase dengan substrat L-DOPA sebesar 11,60±2,30 μg/mL. Sargassum sp. (CP 02) mengandung kelompok senyawa kimia flavonoid, komponen fenolik, saponin, triterpenoid dan steroid.
Keyword: alga coklat, inhibitor tirosinase, Sargassum sp

Judul: The Construction of Greedy SVP LLL Algorithm
Abstrak: A lattice is a set of all integer linear combination of a set of linearly independent vectors in ℝ𝑛���. The independent vectors are called bases of lattice. Any lattice can be generated from many bases, and these bases have the same cardinality. In the lattice, the most fundamental and renowned problem is the Shortest Vector Problem (SVP). SVP is a tracking problem of the shortest nonzero vector in a lattice with equivalent bases. In two dimensions, SVP problem has resolved exactly by Gauss’ algorithm. When the lattice dimension is higher than two, A.K. Lenstra, H.W. Lenstra and L. Lovasz gave a LLL algorithm to compute approximation of nonzero shortest vector in the lattice. Reduced bases solution obtained from LLL algorithm still be an approximation and has polynomial running time of arbitrary dimension which large enough. In 1994, Schnoor and Euchner modified this LLL algorithm as a new variant which later was named deep insertion LLL algorithm. This algorithm is a modified version of the LLL algorithm to the terms of the exchange step to improve the accuracy of output of LLL reduced bases and applying it to the subset sum problem. The purpose of this research are: (1) Reconstruct the LLL algorithm and deep insertion LLL algorithm using a geometric approach. (2) Construct a greedy SVP LLL algorithm. (3) Implement the three algorithms in a symbolic programming language, and evaluate them experimentally. A bases ℬ=[𝐛���1,𝐛���2,…,𝐛���𝑛���] in ℝ𝑚��� is called reduced LLL with parameter 𝛿��� if satisfies: (a) |𝜇���𝑗���𝑖���|≤12, for every integer 𝑖���,𝑗��� with 1≤𝑖���<𝑗���<𝑛���. (b)𝛿���‖𝜋���𝑗���(𝐛���𝑗���)‖2≤‖𝜋���𝑗���(𝐛���𝑗���+1)‖2, for 𝑗���=1,2,…,𝑛���−1,where 𝛿��� is a reduced parameter of real numbers with 14<𝛿���<1. The first requirement is the reduced basis 𝛿��� must “nearly orthogonal” and in its computation case, this requirement can be reached out by using the Gram-Schmidt’s orthogonalization. While the second requirement is called exchange step, or used to called as Lovasz condition. By using both of these requirements, then they establish the LLL algorithm. Then, Schnoor and Euchner modify the LLL algorithm based on the requirements of the exchange step called the deep insertion LLL algorithm, where the exchange step is based on the comparison of the projected vector in orthogonal complement [𝐛���1,𝐛���2,…,𝐛���𝑘���−1]⊥ after j-th reduction. To construct greedy SVP LLL algorithm, the requirements of the exchange step is based on purely by comparing norm of lattice 𝐛���𝑗��� with norm lattice 𝐛���𝑖��� for 𝑖���=1,2,3…,𝑗���−1. The process of insertion reduced vector after the exchange step also has done greedily. Then, we calculate the number of arithmetic operation in greedy SVP LLL algorithm for further analysis. The result of our exprimentation for three algorithms on the certain matrix size shows that the running time of the three algorithms increases propotional to the size of the matrix. The result also shows that by using 𝛿���=34 for the LLL algorithm and the deep insertion LLL algorithm, and the greedy SVP LLL algorithm which is a new variant made by using no parameter of 𝛿���, outperform of the other of two previous algorithm in terms of speed with the same output.
Keyword: LLL algorithm, LLL deep insertion algorithm, greedy SVP LLL algorithm