Judul: Aktivitas antimikroba ekstrak tumbuhan Lumut Hati (Marchantia paleacea) terhadap bakteri patogen dan pembusuk makanan
Abstrak: Liverwort (Marchantia paleaceae)from Cibodas Botanical Garden was used as raw materials in this research. The objective of this research was to assess the antimicrobial activity of liverwort (M. paleacea). Maceration was used to extract the active compound with 4 different solvents i.e ethanol, methanol, ethyl acetate, and hexane. The potency of antimicrobial activity from extract was assesed by agar diffusion method and direct-contact test by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The effectivity of the best extract as antimicrobial agent was tested at pH 4, 6 and 8, and after heating for 20 minutes at 80oC and 100oC.
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Judul: Kajian Aktivitas Antibakteri Daun Gatel (Laportea decumana (Roxb.) Wedd.) dan Daun Benalu Cengkeh
Abstrak: Many researches showed that several plants have a good antibacterial activity. The leaves of gatel and clove mistletoe are empirically used to cure several diseases. The aims of this research were: (1) to study the potential of antibacterial activity of gatel and clove mistletoe hexane, ethyl acetate and methanol extracts against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa by the well diffusion method; (2) to calculate the minimum inhibitory concentration (MIC) value of the potential extracts; and (3) to study the effect of various pH to antibacterial activity of the extracts. The results showed ethyl acetate and methanol extracts of the studied plants have low antibacterial activity against B. cereus and E. coli. Based on the MIC values, the ethyl acetate extract of gatel leaves showed over 99% percent inhibition against E. coli at a concentration of 3.5%, 4.0%, 4.5% and 5.0%. The same result was obtained by modifying the pH (4, 5 and 6) at the extracts concentration of 5% and 10%. The methanol extract of gatel leaves showed below 60% inhibition of B. cereus at a concentration of extract 4.0%, 4.5%, 5.0%, 5.5% and 6.0%, and more than 90% inhibition at the pH. The ethyl acetate extract of clove mistletoe showed more than 98% inhibition againts E. coli at a concentration of 3.5%, 4.0%, 4.5% and 5.0% and at pH 4, 5 and 6. Percent of inhibition less than 50% occured in the methanol extract of clove mistletoe at 4.0%, 4.5%, 5.0%, 5.5% and 6.0% concentration against B. cereus. For the methanol extract of clove mistletoe, the effect of pH variation (4, 5, 6 and 7) resulted in 92%-97% inhibition. The result may increase the utilization of research plant not only for health purposes but also as a natural food preservative and open new possibilities for the development of natural functional foods.
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Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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