Judul: Productivity of phenolic, flavonoid, and antioxidant of Justicia gendarussa at different shades and dose of nitrogen fertilizer
Abstrak: Penelitian ini bertujuan menentukan kombinasi naungan dan dosis pupuk nitrogen yang dapat menghasilkan produktivitas fenolik, flavonoid, dan antioksidan terbaik pada bagian aerial parts dari gandarusa (Justicia gendarussa). Rancangan split-plot digunakan pada penelitian ini dengan naungan (0, 25, dan 50%) sebagai petak utama dan dosis pupuk nitrogen (0, 90, 180, dan 270 kg/ha) sebagai anak petak. Hasil penelitian menunjukkan bahwa produktivitas fenolik, flavonoid, antioksidan, dan bobot kering tertinggi didapat pada perlakuan tanpa naungan dengan dosis pupuk nitrogen 270 kg/ha. Panen bobot kering tanaman mencapai 10,9 gram/tanaman. Produktivitas fenolik adalah 210 mg GAE/tanaman, sedangkan produktivitas flavonoid 112 mg QE/tanaman. Produktivitas antioksidan dengan metode DPPH, ABTS, FRAP, dan CUPRAC berturut-turut adalah 63,5; 334; 171; 525 µmol TE/tanaman. Analisis Pearson menunjukkan bahwa produktivitas fenolik dan flavonoid sangat berkolerasi kuat dengan produktivitas antioksidan. Tanpa naungan dengan dosis pupuk nitrogen 270 kg/ha merupakan kombinasi perlakuan budi daya paling tertinggi berdasarkan parameter penelitian, yaitu naungan dan dosis pupuk nitrogen berbeda., This study aims to determine the combination of shade and the dose of nitrogen fertilizer that can produce the best productivity of phenolic, flavonoid, and antioxidant of aerial parts of gandarusa (Justicia gendarussa). A split-plot design was used in this study with shade (0, 25, and 50%) as the main plot and nitrogen fertilizer doses (0, 90, 180, and 270 kg/ha) as subplots. The results showed the highest productivity of phenolics, flavonoids, antioxidants, and dry weight in the treatment without shading with a dose of 270 kg/ha of nitrogen fertilizer. The dry weight harvest of the plants was 10.9 g/plant. The phenolic productivity was 210 mg GAE/plant, while the productivity of flavonoids was 112 mg QE/plant. Antioxidant productivity using DPPH, ABTS, FRAP, and CUPRAC methods were 63.5; 334; 171; 525 µmol TE/plant, respectively. Pearson correlation shows that the productivity of phenolics and flavonoids is highly correlated with antioxidant productivity. Without shading and a dose of nitrogen fertilizer of 270 kg/ha was the best combination of cultivation treatments based on the research parameters based on shading and dose of nitrogen fertilizer.
Keyword: antioxidant, cultivation, flavonoids, Justicia gendarussa, phenolics

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: