Judul: Aktivitas Buah Bakau Rhizophora stylosa Griff. sebagai Antidiare secara In Vitro
Abstrak: Diare merupakan masalah kesehatan utama yang disebabkan oleh bakteri. Buah bakau (R. stylosa) telah banyak dimanfaatkan oleh masyarakat sebagai obat tradisional. Penelitian ini bertujuan mengetahui efektivitas dan daya hambat ekstrak buah bakau (R. stylosa) terhadap bakteri penyebab diare. Metode penelitian yang digunakan adalah metode sumur agar. Hasil penelitian menunjukkan bahwa rendemen ekstrak metanol merupakan rendemen tertinggi dari ekstrak lainnya dengan nilai 3,45%. Ekstrak metanol memiliki aktivitas antibakteri tertinggi dengan diameter zona hambat sebesar 1-14 mm. Konsentrasi hambat minimum (KHM) bakteri Escherichia coli sebesar 0,5 mg/mL, Staphylococcus aureus sebesar 0,2 mg/mL, Pseudomonas aeruginosa dan Salmonella typhimurium masing–masing sebesar 0,7 mg/mL. Komponen aktif yang terkandung dalam ekstrak metanol adalah alkaloid, tanin, saponin, fenol hidrokuinon, flavonoid, dan triterpenoid. Bioautografi aktivitas antibakteri terhadap bakteri uji E. coli menghasilkan fraksi aktif pada nilai Rƒ 0,64 dan 0,39 sedangkan pada S. aureus nilai Rƒ sebesar 0,64 dan 0,41. Hasil identifikasi dengan pereaksi Dragendorff menunjukkan senyawa tersebut merupakan golongan senyawa alkaloid.
Keyword: antibakteri, antidiare, buah bakau (R. stylosa)

Judul: Aktivitas Antibakteri Ekstrak Daun Bakau Hitam Rhizophora mucronata terhadap Bakteri Penyebab Diare
Abstrak: Diarrhea is one of the major health problems in Indonesia. One of the first caused is bacteria. Leaves of Rhizophora mucronata have been widely used by coastal people as folk medicine for treating diarrhea. The aims of this study was to determine the effectivity and inhibitory of Rhizophora mucronata leaf extract as antibacterial to diarrhea-causing bacteria. The procedure of this research used antibacterial assay determined by agar well diffusion method. The activity of each extract was tested by using diarrhea-causing bacteria. Methanol extract of R. mucronata leaf was the highest yield (21.47%). The active compounds of methanol and aqueous extracts consisted of tannin, saponin, flavonoid, phenol hydroquinone, and triterpenoid. Alkaloid was only showed in methanol extract. Methanol extract had the highest antibacterial activity with inhibition zone of 3-12 mm. Minimum inhibitory concentrations of methanol extract were 0.4 mg/mL (Escherichia coli dan Pseudomonas aeruginosa), 0.2 mg/mL (Staphylococcus aureus), and more than 0.4 mg/mL (EPEC dan Salmonella typhimurium). Bioautography of antibacterial activity toward E. coli revealed the active fractions with Rf value of 0.11 and 0.72. Preliminary identification using Dragendorff spray reagent detected the active compound was alkaloid
Keyword: 

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
Keyword: