Judul: Isolasi bakteri Zymomonas dan seleksi kemampuannya dalam menghasilkan etanol
Abstrak: Sebanyak 20 isolat bakteri hasil isolasi dari nira aren (Arenga pinnata Merr.) yang berlainan, memperlihatkan ciri-ciri khas sebagaimana genus Zymomonas, suatu bakteri anaerobik fakultatif penghasil etanol yang unik. Ketika isolat-isolat tersebut diuji kemampuannya menghasilkan etanol, ternyata semuanya memproduksi etanol de- ngan kadar yang beragam, yaitu antara 1,12% sampai 2,03 %(v/v). Dua isolat diantaranya (NS-1104 dan NB-1122) menunjukkan kemampuan yang kurang lebih setara dengan yang dilaporkan dimiliki oleh galur Zymomonas mobilis 3TH Delft.
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Judul: Produksi Bioetanol dari Nira Aren (Arenga pinnata) oleh Zymomonas mobilis
Abstrak: Ketersediaan bahan bakar minyak (BBM) sebagai energi tak terbarukan semakin lama semakin menipis dan langka khususnya bensin, sehingga dibutuhkan bahan bakar alternatif yang dapat menggantikan bensin. Nira aren merupakan salah satu bahan yang sangat prospektif untuk dijadikan bioetanol karena mengandung gula yang cukup tinggi. Penelitian ini bertujuan untuk mendapatkan kondisi terbaik yang sesuai untuk meningkatkan rendemen bioetanol. Fermentasi dilakukan dengan menggunakan Zymomonas mobilis pada suhu kamar selama 72 jam. Analisa produk dilakukan setiap 12 jam. Dalam penelitian ini dievaluasi pengaruh penggunaan konsentrasi inokulum Zymomonas mobilis, yaitu 5%, 10%, dan 15% (v/v) serta pengaruh konsentrasi gula total pada nira yaitu X1 (18.61%), X2 (24.77%) dan X3 (33.66%). Hasil analisa komponen kimia pada bahan utama nira aren didapatkan kadar gula total sebesar 183.4 g/L, kadar gula pereduksi sebesar 95.16 g/L, total karbon sebesar 8.07% ± 0.05, total nitrogen sebesar 0.089% ± 0.02 dan urea yang dibutuhkan sebesar 1.53 g/ 100 ml. berdasarkan hasil penelitian konsentrasi inokulum terbaik sebesar 15% (v/v) dan konsentrasi gula X1 (18.61%). Konsentrasi gula yang terlalu tinggi menghambat pembentukan produk. Kadar etanol tertinggi sebesar 40.75 g/L atau 4.08% (b/v) dengan biomassa sebesar 8.05 g/L, μ maks 1.56 jam-1, Y x/s sebesar 0.01 g sel/ g substrat, Y p/x sebesar 33.96 g etanol/g sel, Y p/s sebesar 0.27 g etanol/ g substrat, qp sebesar 53.07 g produk/ g sel. jam, dan qs sebesar 194.20 g substrat/ g sel.jam.
Keyword: bioetanol, jumlah inokulum, gula total, nira aren, Zymomonas mobilis

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