Judul: Aktivitas Antibakteri Ekstrak Kulit Petai (Parkia speciosa Hassk.) Terhadap Bakteri Escherichia coli dan Staphylococcus aureus
Abstrak: Parkia speciosa Hassk. is one of edible plants that not developed as medicinal plants yet.The purpose of this research is to study antibacterial activity of peel extract to Staphylococcus aureus and Escherichia coli bacteria with gel diffusion (well method). Peel extract that used in this research were from extraction of n-hexane, ethyl acetate, and ethanol 70%. The concentration were 50, 100, 150, 200, 250, and 300 mg/mL for every solvent. The result of this research showed that ethyl acetate extract has the highest antibacterial activity with 404,25% of 10 mg/mL streptomycin’s antibacterial activity agains Staphylococcus aureus, and 279,12% of 10 mg/mL streptomycin’s antibacterial activity agains Escherichia coli. TLC result showed that ethyl acetate extract with toluene:ethyl acetate (93:7) as solvent has eight spots under 254 nm UV that was mean ethyl acetate extract of petai peel consisted of eight compound. The result of Analysis of Variance with SPSS 16 program for windows showed that variance of solvents and concentration were significantly different for inhibition areas
Keyword: Bogor Agricultural University (IPB), TLC, Staphylococcus aureus, Parkia speciosa Hassk, Escherichia coli, antibacteria

Judul: Antibacterial activity and mechanisms of inhibition of piper betle Linn extract (green variety) towards food pathogenic bacteria
Abstrak: The antibacterial effects of three kinds of Piper betle Linn extract were evaluated towards Escherichia coli and Staphylococcus aureus using well diffusion method. The plant extract, were prepared by solvent extraction of the dried Piper betle leaves using ethanol, ethyl acetate and water. The ethanol extract performed the best antibacterial effect expressed by the diameter of inhibition zone of 24 mm and 14 mm for S. aureus and E. coli respectively. The ethyl acetate extract was also active toward both pathogens with the diameter zone of 16 mm for S. aureus and 12.7 mm for E. coli. The water extract showed the lowest antibacterial activity with the diameter of inhibition zone of 11.5 mm and 10 mm for S. aureus and E. coli respectively.
Keyword: Scanning Electrone Microscope (SEM), Antibacterial activities, Atomic Absorption Spectrophotometer (AAS)

Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular