Judul: Uji Aktivitas Antioksidan Gel Ekstrak Batang Buah Naga Merah (Hylocereus polyrhizus) dengan Metode DPPH.
Abstrak: Batang buah naga merah atau Hylocereus polyrhizus mempunyai kandungan metabolit sekunder yang berperan aktif sebagai antioksidan. Tujuan dari penelitian ini adalah untuk menguji aktivitas antioksidan ekstrak dan gel ekstrak batang buah naga merah. Hasil analisis fitokimia menunjukkan ekstrak batang buah naga merah mengandung alkaloid, flavonoid dan steroid. Aktivitas antioksidan ditentukan dengan metode DPPH. Ekstrak batang buah naga merah memiliki nilai IC50 sebesar 1020.95 ppm dan gel ekstrak batang buah naga merah memiliki nilai IC50 sebesar 77601187.54 ppm. Semakin rendah IC50, maka aktivitas antioksidan semakin tinggi. Berdasarkan uji yang dilakukan, ekstrak dan ekstrak gel memiliki aktivitas antioksidan sangat lemah dengan nilai IC50 lebih dari 200 ppm.
Keyword: antioksidan, batang buah naga merah, DPPH, fitokimia, gel

Judul: Aktivitas Antioksidan Ekstrak Sulur Buah Naga Putih (Hylocereus undatus) dengan Metode DPPH dan Rancimat
Abstrak: Manfaat buah naga sebagai sumber antioksidan telah banyak dilaporkan sebelumnya, namun belum ada yang melaporkan akan manfaat sulur buah naga yang selama ini jumlahnya melimpah. Penelitian bertujuan menganalisis komponen fitokimia, menentukan kadar total fenol dan flavonoid serta menguji aktivitas antioksidan ekstrak sulur buah naga putih. Hasil analisis fitokimia menunjukkan ekstrak aseton dan etil asetat mengandung alkaloid, flavonoid dan steroid, sedangkan ekstrak metanol mengandung alkaloid, flavonoid dan triterpenoid. Hasil penentuan kadar total fenol dan flavonoid menunjukkan kadar tertinggi pada ekstrak aseton sebesar 44.70 GAE mg/g dan 22.28 RUE mg/g. Ekstrak sulur buah naga berpotensi sebagai antioksidan melalui penghambatan radikal bebas DPPH dengan nilai IC50 terbaik pada ekstrak aseton sebesar 25.32 mg/L. Hasil pengujian antioksidan dalam sistem lipid menggunakan metode Rancimat diperoleh faktor proteksi (Fp) tertinggi pada ekstrak metanol sebesar 1.64.
Keyword: antioksidan, fenolik, flavonoid, oksidasi lipid, sulur buah naga putih

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