Judul: Fraksinasi Antioksidan Daun Sirih (Piper betle Linn.) dengan Kromatografi Lapis Tipis
Abstrak: Penambahan antioksidan pada lemak dan minyak maupun baban pangan yang mengandung lemak dan minyak merupakan cara yang paling efektif untuk mencegah oksidasi lemak. Selama ini antioksidan yang digunakan secara luas dalam industri pangan adalah antioksidan sintetik yang banyak menimbulkan kekhawatiran akan efek toksiknya. Oleh karena itu, pencarian antioksidan dari sumber alami giat dilakukan karena dianggap lebih aman untuk dikonsumsi. Salah satu bahan alami yang telah diketahui mengandung antioksidan adalah daun sirih.
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Judul: Mempelajari Penggunaan Kromatografi Kolom untuk Deklorofilasi Ekstrak Antioksidan Daun Sirih Hijau (Piper betle Linn.)
Abstrak: Daun sirih telah diketahui mempunyai potensi untuk dikembangkan menjadi sumber antioksidan alami. Hal ini didasarkan pada beberapa penelitian yang menunjukkan bahwa ekstrak antioksidan daun sirih rnempunyai aktivitas antioksidasi yang lebih tinggi dari BHA pada konsentrasi 200 ppm (Cahyono, 1995). Akan tetapi, ekstrak ini mempunyai warna yang hijau pekat. Warna ini diduga berasal dari klorofil yang ikut terekstrak. Oleh karena itu, dalam penelitian ini dilakukan deklorofilasi (penghilangan klorofil) dari ekstrak dengan menggunakan kromatografi kolom sehingga didapat ekstrak yang tidak berwarna dan tetap mempunyai aktivitas antioksidasi yang tinggi.
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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