Judul: Penurunan Tegangan Permukaan dan Daya Hambat Escherichia coli dan Staphylococcus aureus oleh Ekstrak Daun Graptophyllum pictum (L.) Griff
Abstrak: Wungu (Graptophyllum pictum (L.) Griff) merupakan salah satu tanaman obat unggulan khas Indonesia. Metabolit sekunder pada daun wungu berpotensi menurunkan tegangan permukaan dan menghambat aktivitas antibakteri. Penelitian ini bertujuan mengetahui nilai tegangan permukaan dan aktivitas antibakteri terhadap bakteri Escherichia coli dan Staphylococcus aureus oleh ekstrak air, metanol, dan etil asetat daun wungu. Pada penelitian ini, daun wungu diekstraksi menggunakan 3 jenis pelarut, yaitu air, metanol dan etil asetat. Penelitian dilanjutkan dengan mengukur tegangan permukaan menggunakan metode cincin du-Nouy dan aktivitas antibakteri menggunakan metode difusi cakram. Hasil penelitian menunjukkan ekstrak daun wungu dapat menurunkan tegangan permukaan dengan nilai Konsentrasi Misel Kritik (KMK) ekstrak etil asetat sebesar 0.18%, ekstrak metanol (0.40%), dan ekstrak air (0.84%). Ekstrak etil asetat daun wungu merupakan ekstrak terbaik dengan nilai KMK terendah yaitu 0.18%. Penelitian ini juga menunjukkan ekstrak air dan metanol daun wungu pada konsentrasi 10000 ppm tidak memiliki daya hambat terhadap bakteri uji Escherichia coli dan Staphylococcus aureus.
Keyword: antibakteri, Graptophyllum pictum, tegangan permukaan

Judul: Aktivitas Inhibisi Enzim α-Glukosidase dan Antioksidan dari Ekstrak Etanol Daun Wungu (Graptophyllum pictum (L.) Griff) dan Partisinya
Abstrak: Wungu leaves (Graptophyllum pictum (L.) Griff) is a plant that is widely used in treating a variety of ailments, including diabetes and known to contain phenolic compounds that have antioxidant activity. The purpose of this study was to determine the inhibition of the enzyme α-glucosidase and antioxidant activities of ethanol extracts and fractions of diethyl ether, ethyl acetate, and butanol from wungu leaves (Graptophyllum pictum (L.) Griff) by in vitro studies. Extraction of wungu leaves was done by maceration and the fractination was done through liquid-liquid extraction. Results showed that ethanol extracts and its fraction have no inhibitory activity toward α-glucosidase, but it was potentially as antioxidant through inhibition of radical DPPH. Ethyl acetate fraction (500 ppm) can capture the DPPH radical 74.105% with IC50 values of 68.11 ppm which is the highest antioxidant activity and is followed by the fraction of butanol, ethanol, and diethyl ether.
Keyword: DPPH, wungu leaves, α-glucosidase, antioxidant, antidiabetic

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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