Judul: Phenolic Content and Antioxidant Activity Gendarussa  Methanol Extract Cultivated with the Combination of Manure and NPK Fertilizers
Abstrak: Pengaplikasian pupuk organik dan anorganik akan memengaruhi kadar senyawa fenolik tanaman gandarusa. Penelitian ini bertujuan menentukan metode budidaya terbaik melalui aplikasi pupuk kandang, NPK, atau kombinasi keduanya terhadap kadar total fenolik dan aktivitas antioksidan ekstrak metanol daun dan batang gandarusa. Tanaman gandarusa dibudidaya dengan enam perlakuan, yakni kontrol (T1), pupuk kandang (T2), NPK (T3), 50% pupuk kandang + 50% NPK (T4), 50% pupuk kandang + 10% NPK (T5), dan 10% pupuk kandang + 50 % NPK (T6). Total fenolik diukur dengan metode Folin Ciocalteu. Aktivitas antioksidan diukur dengan metode Ferric Reducing Antioxidant Power (FRAP) dan 2,2’-difenil-1-pikrilhidrazil (DPPH). Kadar total fenolik tertinggi diperoleh pada perlakuan T3 daun dan T6 batang (4,28 dan 2,54 mg GAE/g bobot kering). Aktivitas antioksidan FRAP tertinggi diperoleh pada perlakuan T3 daun dan batang, sedangkan pada metode DPPH perlakuan T1 daun dan T6 batang menunjukkan aktivitas tertinggi (11,54; 5,31; 0,64; 0,19 µmol TE/g bobot kering). Kadar total fenolik hanya menunjukkan korelasi yang positif dan signifikan terhadap aktivitas antioksidan sampel daun metode FRAP., The application of organic and inorganic fertilizers affects to the levels of gendarussa plant’s phenolic compounds. This research aims to determine the best cultivation method using manure, NPK, or the combination to achieve the highest phenolic content and antioxidant activity in methanol extract of gendarussa. Gendarussa plants are cultivated with six treatments, control (T1), manure (T2), NPK (T3), 50% manure + 50% NPK (T4), 50% manure + 10% NPK (T5), and 10% manure + 50% NPK (T6). Total phenolic was measured by Folin Ciocalteu method. Antioxidant activity was determined by FRAP and DPPH assay. The highest phenolic content was obtained from sample T3 (leaf) and T6 (stem) (4,28 and 2,54 mg GAE/g dry weight). The highest FRAP antioxidant activity was obtained from sample T3 of both leaf and stem, while the highest DPPH antioxidant acitivity was obatained from sample T1 (leaf) and T6 (stem) (11,54; 5,31; 0,64; 0,19 µmol TE/g dry weight). Total phenolic content only shows a positive and significant correlation to the antioxidant activity of leaf samples using FRAP assay.
Keyword: Antioxidant activity, Gendarussa, Manure fertilizer, NPK fertilizer, Phenolic

Judul: Aktivitas Antioksidan dan Total Flavonoid Ekstrak Etanol Gandarusa (Justicia gendarussa Burm. F.) yang Diberi Pupuk NPK, Kandang, dan Kombinasi
Abstrak: Gandarusa (Justicia gendarussa Burm. F.) merupakan tanaman yang sering dimanfaatkan karena kandungan antioksidannya. Penelitian ini bertujuan menentukan kadar total flavonoid dan aktivitas antioksidan, serta menganalisis korelasi antara kadar total flavonoid dan aktivitas antioksidan dari ekstrak etanol daun dan batang gandarusa dengan komposisi pemupukan berbeda. Kadar total flavonoid diukur dengan metode aluminium klorida. Aktivitas antioksidan diukur dengan metode Cupric Reducing Antioxidant Capacity (CUPRAC) dan 2,2-diphenyl-1-picrylhydrazyl (DPPH). Kadar total flavonoid daun dan batang tertinggi dihasilkan dengan tanpa pemupukan sebesar 5,23 dan 1,85 mg QE/g. Aktivitas antioksidan tertinggi metode CUPRAC diperoleh pada perlakuan pupuk NPK pada sampel daun dan batang yaitu sebesar 55,25 dan 20,39 µmol TE/g, sedangkan untuk DPPH diperoleh pada perlakuan 50% pupuk kandang dan 50% pupuk NPK untuk sampel daun, dan 50% pupuk kandang dan 10% pupuk NPK untuk sampel batang, dengan nilai berturut-turut 0,39 dan 0,08 µmol TE/g. Kadar total flavonoid daun dan aktivitas antioksidan berkorelasi negatif dan tidak signifikan, sedangkan pada batang bersifat positif dan signifikan secara statistik., Gandarusa (Justicia gendarussa Burm. F.) is often used because of its antioxidant content. This study aimed to determine the total flavonoid content and antioxidant activity, and to analyze the correlation between total flavonoid content and antioxidant activity of ethanol extract of the leaves and stems of gandarusa with different fertilizer composition. Total flavonoid content was measured with aluminum chloride method. Antioxidant activity was measured using CUPRAC and DPPH method. The highest flavonoid contents of leaf and stem sample were 5,23 and 1,85 mg QE/g obtained from treatment without fertilization. The highest antioxidant activity using CUPRAC method were 55,25 and 20,39 µmol TE/g obtained from NPK fertilizer, while for DPPH was obtained from treatment of 50% manure and 50% NPK fertilizer for leaf samples, and 50% manure and 10% NPK fertilizer for stem samples, respectively 0,39 and 0.08 mol TE/g. Leaf’s flavonoid content and antioxidant activity were negatively correlated and not significant, while the correlation in stem was positive and statistically significant.
Keyword: Antioxidant activity, Aktivitas Antioksidan, Manure fertilizer, NPK fertilizer, Flavonoid, Plant nutrition

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
Keyword: