Judul: Aktivitas Antioksidan dan Kandungan Senyawa Dugaan pada Ekstrak Kemenyan (Styrax benzoin)
Abstrak: Kemenyan (Styrax benzoin) merupakan hasil hutan bukan kayu dengan marga Styracaceae dan ordo Ebenales. Kadar fenolik dan flavonoid yang terkandung pada spesies ini menjadi tolok ukur terhadap aktivitas antioksidan yang dimiliki. Tujuan penelitian ini adalah menentukan senyawa dugaan pada ekstrak teraktif antioksidan. Ekstrak metanol difraksionasi dengan teknik partisi cair-cair menggunakan pelarut n-heksana, kloroform, dan etil asetat. Aktivitas antioksidan dari setiap fraksi ditentukan dengan menggunakan metode 2,2-difenil-1-pikrilhidrazil. Fraksi kloroform memiliki aktivitas antioksidan terkuat dengan nilai IC50 37.23 μg/mL dan kadar fenolik serta flavonoid total 410.97 mg EAG/g dan 521 mg EK/g. Analisis menggunakan kromatografi cair spektrometri massa menunjukkan keberadaan 5 senyawa yang diduga memiliki aktivitas sebagai antioksidan, yaitu 1-(2,4-dihidroksifenil)-2-(4-hidroksifenil) propana-1-on, kromon, 5,7-dihidroksi-2-(4-hidroksifenil)-6,8-dimetil-2,3-dihidroksikromon-4-on, 5,7-dihidroksi-2-(4-hidroksifenil)-8-(3 metilbut-2-enil)-2,3-dihidrokromon-4-on, dan prolifisin A.
Keyword: Antioksidan, kemenyan, total fenolik, total flavonoid

Judul: Penentuan Total Fenolik, Flavonoid, dan Aktivitas Antioksidan Ekstrak Kulit Kayu Mahoni (Swietenia Macrophylla King) pada Berbagai Konsentrasi Etanol.
Abstrak: Pohon mahoni (Swietenia Macrophylla King) banyak ditemukan di dataran tinggi di Indonesia dan umumnya digunakan sebagai obat dan pestisida alami. Penelitian terdahulu sudah dilakukan mengenai aktivitas antioksidan dari berbagai macam pelarut, namun demikian belum diketahui pengaruh perbedaan konsentrasi pelarut etanol terhadap kandungan senyawa fenolik, flavonoid, dan aktivitas antioksidan kulit kayu mahoni. Penelitian ini bertujuan untuk menganalisis pengaruh perbedaan konsentrasi pelarut etanol terhadap senyawa metabolit sekunder dan aktivitas antioksidan. Kulit kayu mahoni diekstraksi dengan metode maserasi menggunakan pelarut air dan beberapa konsentrasi etanol (30%, 50%, 70%, dan 96%). Penentuan kadar total fenolik dan flavonoid menggunakan metode spektrofotometri, dan aktivitas antioksidan diukur menggunakan metode 1,1- diphenyl-2-picrylhydrazyl (DPPH). Hasil penelitian menunjukkan bahwa pelarut etanol 70% menghasilkan kadar total fenolik terbesar (123,16 mg GAE/g), sedangkan kadar total flavonoid terbesar dari etanol 50% (8,40 mg QE/g), dan aktivitas antioksidan terbesar terdapat pada pelarut air (27,22 µmol TE/g).
Keyword: antioksidan, DPPH, kulit kayu, mahoni

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