Judul: Surface Tension Phenomenon, Foam Stability, and Antibacterial on Extract Phase of Lerak Fruit (Sapindus rarak)
Abstrak: Buah lerak (Sapindus rarak) mengandung saponin alami yang memiliki aktivitas antibakteri. Penelitian ini bertujuan mendapatkan fase ekstrak teraktif dari buah tersebut dan mengkaji fenomena tegangan permukaan, stabilitas busa, dan aktivitas antibakteri terhadap Propionibacterium acnes. Sampel dimaserasi menggunakan pelarut etanol 70%. Ekstrak etanol dilarutkan dengan etanol 70% kemudian dipartisi dengan dua macam pelarut, yaitu n-heksana dan etil asetat. Masing-masing fase ekstrak ditentukan tegangan permukaan, stabilitas busa, dan aktivitas antibakteri terhadap P. acnes. Hasilnya menunjukkan bahwa fase ekstrak etil asetat memiliki tegangan permukaan terbaik (konsentrasi misel kritis paling rendah pada 0,017%), stabilitas busa 2 kali lipat lebih tinggi (71%) dibandingkan fase lainnya, walaupun aktivitas antibakterinya masih tergolong rendah (konsentrasi hambat minimum >10mg/mL). Dengan demikian, fase etil asetat merupakan fase teraktif yang berpotensi digunakan sebagai bahan dasar pembuatan sabun untuk kulit wajah., The lerak fruit (Sapindus rarak) contains natural saponins, which have antibacterial activity. This study aims to obtain the fruit’s most active extract phase and examine surface tension, foam stability, and antibacterial activity toward Propionibacterium acnes. The sample was macerated using 70% ethanol. The ethanol extract was dissolved in 70% ethanol and partitioned using two different solvents, n-hexane and ethyl acetate. The surface tension, foam stability, and antibacterial activity toward P. acnes were determined for each extract phase. The results showed that the ethyl acetate extract phase gave the best surface tension (lowest critical micelle concentration at 0.017%), and foam stability was twice as high (71%) as the other extract phases. However, antibacterial activity was relatively low (minimum inhibitory concentration >10 mg/mL). Thus, the ethyl acetate phase is the active phase that can be used as a basic ingredient for facial soap.
Keyword: antibakteri, saponin, sapindus rarak, stabilitas busa, tegangan permukaan

Judul: Antibacterial Activity of Meranti Bark Ethanol Extract Againts Staphylococcus aureus
Abstrak: Ekstrak kulit kayu meranti diketahui memiliki aktivitas antibakteri. Dalam penelitian ini, berbagai konsentrasi etanol, 50% (E50), 75% (E75), dan 100% (E100) digunakan sebagai pelarut untuk mengekstraksi kulit kayu menggunakan metode ekstraksi soxhlet. Hasil ekstrak ditentukan dan kemudian dilakukan uji aktivitas antibakteri terhadap S. aureus menggunakan metode difusi cakram. Kandungan fitokimia ditentukan secara kualitatif mengacu pada metode Harborne. Komposisi kimia ekstrak dengan aktivitas antibakteri tertinggi dianalisis dengan LC-MS dan dikonfirmasi dengan spektroskopi FTIR. Hasil penelitian menunjukkan bahwa rendemen ekstrak tertinggi diperoleh pada E75 (8,39%), diikuti oleh E50 (7,86%), dan E100 (6,58%). Ekstrak tersebut dapat menghambat pertumbuhan S. aureus pada kisaran sedang sampai kuat. Analisis fitokimia dan spektrum FTIR mengkonfirmasi adanya kandungan flavonoid, fenolhidrokuinon, tanin, saponin, dan triterpenoid dalam ekstrak. Analisis LC-MS menunjukkan adanya (+)-Nootkatone, aurantimide acetate, Vitisin C, Kievitone yang diduga berperan dalam aktivitas antibakteri terhadap S. aureus., Meranti bark extract has been known posses the antibacterial activity. In this study, various concentrations of ethanol, 50% (E50), 75% (E75), and 100% (E100) was used as solvent to extract the bark using soxhlet extraction method. The extract yields were determined and then subjected to the antibacterial activity assay against S. aureus using disc diffusion method. The phytochemicals content was determined qualitatively reffered to Harborne method. The chemical composition of the extract with the highest antibacterial activity was analyzed by LC-MS and confirmed by FTIR spectroscopy. The study showed that the highest extract yield was obtained in E75 (8.39%), followed by E50 (7.86%), and E100 (6.58%). The extract can inhibited the growth of S. aureus in the range of moderate to strong. The phytochemical analysis and FTIR spectrum confirmed flavonoid, phenolhydroquinone, tannin, saponin, and triterpenoid in the extract. LC-MS analysis showed the presence of (+)-Nootkatone, aurantimide acetate, Vitisin C, Kievitone that suggested have a role in the antibacterial activity against S. aureus
Keyword: antibakteri, konsentrasi pelarut, etanol, meranti, rendemen, sokhlet, antibacterial, ethanol solvent concentration, meranti, soxhlet, yield

Judul: Query Expansion based on Bilingual Dictionary Using Conditional Probability
Abstrak: Query expansion is a technique that can be used to bridge vocabulary gaps between queries and documents in the collection. With query expansion, user will be helped to formulate queries well so that user will optimize the search result. In this study, the expansion term was resulted from the translation of bilingual dictionary. Subsequently, several terms of expansion were elected based on the closeness of its relationship with the original query. This research showed that conditional probability can be used to select expansion term in bilingual translation method query expansion. The result of 1000 documents was more than 97% relevan document can be retrieved by this system. The more expansion term used, the larger number relevan document was retrieved.
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