Judul: Aktivitas Antioksidan Ekstrak Etanol Daun Serai (Cymbopogon citratus) dan Potensinya Sebagai Pencegah Oksidasi Lipid
Abstrak: Cymbopogon citrates is usually used as spices by Indonesian people. The utilization of lemongrass is only limited on it stem, but the leaf remain as waste. The aim of this research was to analyze phytochemical components and to determine the phnolic content and antioxidant assay with ethanol solvent each 30%, 70% and 96%. The extraction of lemongrass leaf was performed by maceration. The result of phytochemical analysis indicated that the ethanolic extract of lemongrass leaf contains alkaloid, saponin, tannin, flavonoid, phenol and steroid. The phenol content determination was performed by Folin- Ciocalteau method with the highest phenolic content was obtained on ethanolic extract 30% was 50.017 GAE (Gallic Acid Equivalent) mg/g. The ethanol extract of lemongrass leaves through its inhibitory potency as an antioxidant against free radical DPPH (2,2-diphenyl-1-pikrylhydrazyl) with with the highest IC50 on 70% ethanol was 79.444 mg/L. The antioxidant activity on lipid system with rancimat method was obtained on 70% ethanol as 1.19 and the longest induction time was 6.15 hours.
Keyword: Bogor Agricultural University (IPB), DPPH., rancimat, total phenolic, antioxidant, lemongrass leaf

Judul: Aktivitas Antibakteri dan Toksisitas Minyak Serai Dapur (Cymbopogon citratus) dengan Perlakuan Pemekatan pada Suhu Berbeda
Abstrak: Lemongrass (Cymbopogon citratus) is a species of the genus Cymbopogon that produces essential oils with a distinctive fragrance. Lemongrass oil can be an alternative choice of natural antibacterial agents during the Covid-19 pandemic in hand soap and hand sanitizer because it is easy to obtain and the price is affordable. Lemongrass essential oil is reported to contain many chemical compounds that contribute to its activity. Chemical compounds reported in lemongrass essential oil include β-mirsen, 3-undekuna, neral, geranial, nerol, geranil asetat and juniper camphor. Differences in the composition of chemical compounds in essential oils can affect the bioactivity of this essential oils. The differences in the composition of chemical compounds in lemongrass essential oil are influenced by several factors, including the treatment in the distillation process and after the distillation process. Evaluation of the effect of post-distillation temperature on the chemical components in lemongrass oil is an aspect that we need to work on as an effort to ensure its quality and efficacy. In this study, the procedure was started by distillation of lemongrass at a temperature of 100–105ºC for 3,5 hours and then stored in the refrigerator. As a comparison, commercial lemongrass oil was provided and then concentrated using a rotary evaporator at different temperatures, at 30, 40, and 50 ºC. There are five samples of lemongrass oil which are then ready to be analyzed. The toxicity test was carried out using the brine shrimp lethality test (BSLT). The results of the BSLT test showed that the five samples had an LC50 value of <1000 ppm. In addition to BSLT, antibacterial activity tests were carried out on lemongrass oil which included minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Antibacterial test was conducted against S. aureus and S. epidermidis by disc method. The result showed that lemongrass oil has very strong antibacterial properties against S. aureus and is in the strong category against S. epidermidis. Meanwhile, the MIC values of lemongrass oil without evaporation treatment was 1250 ppm and 625 ppm, respectively against S. aureus and S. epidermidis. The MBC values of the sample was 2500 ppm and 10000 ppm against S. aureus and S. epidermidis, respectively. While the MIC values of lemongrass oil concentrated at 40 ºC were 5000 ppm and 2500 ppm against S. aureus and S. epidermidis, respectively. The analysis of chemical composition using GC-MS shows that in lemongrass oil without evaporation treatment there are 13 compounds detected with the abundance of each compound > 1% while in lemongrass oil evaporated at 40 ºC for 11 compounds was detected. The main constituent in lemongrass oil was citral, neral and β-mirsen.
Keyword: antibacterial, BSLT, GC-MS, lemongrass

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