Judul: Penentuan Struktur Molekul dari Fraksi Air Tumbuhan "Sarang Semut" Mymecodia pendens Merr. & Perry yang mempunyai aktivitas Sitoteksik dan sebagai Antioksidan
Abstrak: Kemajuan bidang industri berbanding terbalik dengan kualitas lingkungan, yang menyebabkan munculnya penyakit-penyakit degeneratif seperti kanker hati, jantung, arthritis, diabetes dan sebagainya. Penyakit generatif umumnya terjadi akibat gaya hidup modern, polusi, stress, makanan cepat saji dan sebagainya yang menyebabkan stress oksidatif atau ketidak seimbangan antara jumlah oksidan dan prookasidan dalam tubuh. Pada kondisi ini, aktivitas molekul radikal bebas atau spesies oksigen reaktif (SOR) dapat mengganggu proses metabolisme sel dan menyebabkan kerusakan pada DNA, protein dan lipoprotein di dalam tubuh. Resiko ini sebenarnya dapat dikurangi dengan mengkonsumsi antioksidan dalam jumlah yang cukup. Meskipun demikian umumnya masyarakat tidak terlalu peduli dengan hal-hal tersebut.
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Judul: Analysis of Antioxidant Activity of Flavonoid Compounds from Moringa Oleifera Leaves Using Density Functional Theory
Abstrak: Perubahan gaya hidup dan pola makan manusia telah meningkatkan risiko penyakit degeneratif akibat oksidasi berlebihan dan pembentukan radikal bebas. Radikal bebas ini berhubungan dengan penyakit serius seperti aterosklerosis, diabetes, dan kanker. Antioksidan dari tanaman, seperti flavonoid dalam daun kelor (Moringa Oleifera) yaitu quercetin, myricetin dan kaempferol, dapat menghambat kerusakan oksidatif ini. Analisis sifat aktivitas antioksidan diperlukan untuk mengetahui senyawa flavonoid mana yang paling efektif dalam pembersihan radikal bebas. Metode perhitungan komputasi DFT dapat menjadi solusi dalam studi teoritis untuk menganalisis sifat tersebut, dengan fungsi exchange-correlation B3LYP dan basis set def2/SVP. Perhitungan yang dilakukan pada penelitian ini adalah optimasi molekul, frekuensi vibrasi, dan single point energy yang dilakukan pada fase gas dan fase pelarut air dengan nilai parameter pelarut air diambil dari model CPCM (Conductor-like Polarizable Continuum Model) pada Software ORCA 5.2.0 sebagai pelarut implisit (Implicit Solvent). Efektifitas antioksidan dianalisis berdasarkan tiga mekanisme interaksi senyawa flavonoid, yaitu HAT, SET-PT, dan SPLET dengan memperoleh nilai terendah dari parameter-parameter termodinamika berupa BDE, IP+PDE, dan PA+ETE pada ketiga mekanisme tersebut. Selanjutnya, dianalisis nilai perhitungan parameter reaktivitas global dengan nilai HOMO dan LUMO yang diperoleh dari perhitungan single point energy dari ketiga senyawa flavonoid tersebut pada fase gas dan fase pelarut air. Sifat antioksidan yang baik ditandai dengan nilai energi gap (?E) yang kecil, electronegativity(?) yang tinggi, potensial kimia (µ) yang lebih positif, hardness (?) yang rendah, softness (s) yang tinggi, electrophilicity (?) yang besar, nucleophilicity (e) yang kecil, energi ionisasi (IE) yang rendah, dan afinitas elektron (EA) yang tinggi. Kata kunci: antioksidan, DFT, CPCM, Quercetin, Myricetin dan Kaempferol, Human lifestyle and dietary habits have increased the risk of degenerative diseases due to excessive oxidation and the formation of free radicals. These free radicals are associated with serious diseases such as atherosclerosis, diabetes, and cancer. Plant-based antioxidants, such as the flavonoids quercetin, myricetin, and kaempferol found in Moringa Oleifera leaves, can inhibit this oxidative damage. Analyzing the antioxidant activity properties is necessary to determine which flavonoid compounds are most effective in free radicals scavenging. Computational DFT calculations can be a solution in theoretical studies to analyze these properties, using the B3LYP exchange-correlation function and def2/SVP basis set. The calculations performed in this study include molecular optimization, vibrational frequencies, and single point energy, conducted in both gas phase and aqueous solvent phase, with the aqueous solvent parameters taken from the CPCM (Conductor-like Polarizable Continuum Model) model in ORCA 5.2.0 software as the implicit solvent. Antioxidant effectiveness is analyzed based on three interaction mechanisms of flavonoid compounds, namely HAT, SET-PT, and SPLET, by obtaining the lowest values of thermodynamic parameters such as BDE, IP+PDE, and PA+ETE in these three mechanisms. Furthermore, the global reactivity parameters are analyzed with HOMO and LUMO values obtained from single point energy calculations of the three flavonoid compounds in both gas phase and aqueous solvent phase. Good antioxidant properties are indicated by a small energy gap (?E), high electronegativity (?), more positive chemical potential (µ), low hardness (?), high softness (s), large electrophilicity (?), small nucleophilicity (e), low ionization energy (IE), and high electron affinity (EA). Keywords: Antioxidant, DFT, CPCM, Quercetin, Myricetin dan Kaempferol
Keyword: Antioksidan, antioxidant, DFT, CPCM, Quercetin, Myricetin, Kaempferol, Teori Fungsi Kerapatan

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