Judul: Dugaan Golongan Senyawa Toksik Fraksi Aktif Etil Asetat Karang Lunak Dendronephthya Asal Lampung
Abstrak: Dendronephthya merupakan salah satu karang lunak yang tumbuh subur di wilayah pesisir Indonesia. Penelitian ini bertujuan menentukan fraksi paling toksik serta mengidentifikasi dugaan golongan senyawa aktif yang terkandung dalam ekstrak Dendronephthya. Sampel dimaserasi dengan pelarut metanol, kemudian residunya di maserasi kembali dengan pelarut n-heksana. Ekstrak metanol dipartisi cair-cair dengan pelarut etil asetat. Toksisitas ekstrak diujikan dengan metode uji letalitas larva udang. Ekstrak etil asetat memiliki toksisitas paling tinggi dengan LC50 sebesar 333 g/mL. Ekstrak ini kemudian difraksionasi lebih lanjut dengan kromatografi lapis tipis preparatif dan menghasilkan 3 fraksi. Fraksi 3 memiliki toksisitas paling tinggi dengan LC50 77 g/mL. Hasil uji fitokimia dan spektrum inframerah menunjukkan pada ekstrak etil asetat Dendronephthya diduga mengandung steroid, flavonoid, dan fenolik pada fraksi tersebut.
Keyword: Dendronephthya sp, flavonoids, Phenolic, Steroids, Toxicity, Fraksi paling toksis, Fitokimia eksrak, Toksisitas eksrak, Toksisitas fraksi, Komponen kimia

Judul: Uji Toksisitas Ekstrak Etil Asetat Teraktif Daun Dandang Gendis (Clinacanthus nutans) Menggunakan Uji Letalitas Larva Udang
Abstrak: Dandang gendis (Clinacanthus nutans) is a medical herb commonly used as a traditional medicine as antimalarial and antidiabetic. This study was started with maceration of the dried leaves of dandang gendis with ethanol,and then partitioned using n-hexane. The ethanol extract free of nonpolar compounds was then partitioned with ethyl acetate. The ethanol crude extract, n-hexane fraction, and ethyl acetate fraction were tested by using brine shrimp lethality test to determine the toxicity of each extract. The ethyl acetate fraction showed the highest activity with 50% lethal concentration (LC50) of 32 mg/L. Re-extraction of ethanol extract free of nonpolar compounds by using ethyl acetate in 90 minutes by three times extraction with material:solvent ratio of 1:2 resulted LC50 value of 29.02 mg/L. Phytochemical assay results showed that the ethyl acetate extract of dandang gendis leaves contained saponins, alkaloids, steroids, and flavonoids. Re-extraction of ethyl acetate extract contained higher flavonoids than ethyl acetate extract from the first extraction.
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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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