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: Aktivitas Antifungi Ekstrak Daun Sirih Hijau (Piper betle L.) Terhadap Candida tropicalis
Abstrak: Betel leaf (Piper betle L.) is a medicinal plant that is widely used in treating various diseases, including vaginal candidiasis. One of the causes of this disease is Candida tropicalis. The aim of this study was to decide the effective concentration of the green betel leaf extract (Piper betle L.) as an anti-candidiasis (in vitro) against Candida tropicalis. Optimization of the effective concentration used the well diffusion method and analysis of the compounds used GC-MS. Green betel leaves were extracted using three solvents : water, ethanol 70%, and acetone. The percentage yield of acetone extract was greater than the water and the ethanol extracts, that was 19.64 %. From the result of phytochemical analysis, it was known that the acetone extract contains saponins, tannins, triterpenoids and steroids. Antibacterial activity test showed that all extracts have inhibitory effect on Candida tropicalis. Based on research data, acetone extract at 6.25 mg/mL is chosen as the effective concentration. The chemical components of green betel leaf acetone extract that have potential as anti-Candida tropicalis were benzoic acid; 2-hexadecen-1-ol, 3,7,11,15-tetramethyl and neophytadiene.
Keyword: Anti-candidiasis, Candida tropicalis, Piper betle L.

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