Judul: Isolasi dan Identifikasi Golongan Flavonoid daun Dandang  Gendis (Clinacanthus nutans) Berpotensi sebagai Antioksidan
Abstrak: Isolation of flavonoid was carried out by extracting the leaves of Dandang Gendis (Clinacanthus nutans) with 70% ethanol. Maceration was used as a method of extraction. The extract then was concentrated and calculated for its yield, phytochemical test, and flavonoid group test. The extract were hydrolysed and partitioned in ethyl acetate, then fractionated using column chromatography through gradient elusion process between a mixture of methanol:chloroform. Antioxidant test was conducted by FTIR (Fourier Transform Infrared) to analyze the functional groups present in the most active fractions. The 70% ethanol gave 34.58% yield. Phytochemical test was positive for alkaloids, triterpenoids, and flavonoids. Flavonoid group test was positive for flavon and flavonol. The most active fraction was fraction l with IC50 value of 48.42 mg/L, flavonoid group test was positive for flavon and flavonol, and FTIR analysis results showed the functional groups of O-H, C = O, C-O, aromatic C=C, and aliphatic C-H.
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Judul: Isolation of Phenolic Active Compounds as Antioxidant from Dandang Gendis (Clinachantus nutans) Leaves.
Abstrak: Daun dandang gendis (Clinacanthus nutans) merupakan salah satu tanaman obat yang berpotensi sebagai antioksidan. Tujuan penelitian ini ialah mengisolasi senyawa bioaktif dari tanaman yang termasuk famili Acantaceae untuk mendapatkan komponen aktif senyawa fenolik dengan aktivitas antioksidan yang tinggi. Aktivitas antioksidan ditentukan dengan metode penggaitan radikal bebas 1,1-difenil-2-pikrilhidrazil. Dari hasil fraksinasi menggunakan kromatografi lapis tipis preparatif dengan eluen n-butanol:air:asam asetat (4:5:1) diperoleh 3 fraksi. Fraksi teraktif ialah fraksi 2 dengan nilai konsentrasi hambat 50% (IC50) 89.50 mg L-1, sedangkan IC50 untuk senyawa kontrol, hidroksi toluena terbutilasi (BHT) sebesar 6.87 mg L-1. Hasil ini menyimpulkan bahwa aktivitas antioksidan fraksi 2 jauh lebih rendah bila dibandingkan dengan aktivitas BHT. Uji senyawa fenolik dilakukan dengan kromatografi gas‒spektrometer massa dan diduga terdapat 3 senyawa fenolik, yaitu p-isopropenilfenol, o-hidroksiasetofenon, dan p-hidroksiasetofenon.
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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