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: Phenolic Content and Antioxidant Activity of Gendarussa Ethanolic Extract Cultivated with Manure and NPK Fertilizer
Abstrak: Nutrisi dapat mempengaruhi kandungan fenolik tanaman Justicia gendarussa Burm f. (gandarusa). Penelitian ini bertujuan memperoleh informasi komposisi pemupukan gandarusa dengan kadar total fenolik dan aktivitas antioksidan tertinggi, dan menganalisis korelasi antara kadar fenolik dan aktivitas antioksidan yang diperoleh. Pupuk yang digunakan adalah pupuk kandang, NPK, dan kontrol tanpa pemupukan. Laju aplikasi pemupukan 10% dan 50%. Sampel dimaserasi dengan etanol. Kadar total fenolik diukur dengan metode Folin-Ciocalteu. Aktivitas antioksidan diukur dengan metode Ferric Reducing Antioxidant Power (FRAP) dan 2,2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Korelasi dianalisis dengan uji Pearson’s. Kadar total fenolik daun dan batang tertinggi diperoleh pada perlakuan 50% pupuk kandang dan 50% pupuk NPK sebesar 8 dan 5 mg EAG g-1 bobot kering. Aktivitas antioksidan tertinggi diperoleh pada sampel daun perlakuan 50% pupuk kandang dan 50% pupuk NPK (FRAP) dan perlakuan pupuk NPK (ABTS), serta sampel batang perlakuan pupuk NPK (FRAP) dan kontrol (ABTS), dengan nilai berturut-turut 21, 25, 12 dan 27 µmol KAET g-1 bobot kering. Kadar total fenolik daun dan aktivitas antioksidannya berkorelasi positif, sedangkan korelasi pada batang tidak bersifat signifikan secara statistik., Nutrient can affect gendarussa plant’s phenolic content. The objective of the research is to obtain the fertilizing condition yielding the highest phenolic content and antioxidant activity on gendarussa, and analyze the correlation between the obtained phenolic content and antioxidant activity. Fertilizers used were manure, NPK, and no fertilizer being the control. Fertilizing application rate were 10% and 50%. Sample was macerated with ethanol. Total phenolic content was measured with Folin-Ciocalteu method. Antioxidant activity was measured with FRAP and ABTS assay. Correlation was analyzed with Pearson’s test. The highest phenolic contents were 8 and 5 mg GAE g-1 dry weight obtained from treatment 50% manure and 50% NPK of leaf and stem sample. The highest antioxidant activity were 21, 25, 12 and 27 µmol TEAC g-1 dry weight obtained from leaf 50% manure and 50% NPK (FRAP) and NPK sample (ABTS), and stem’s NPK (FRAP) and control (ABTS) sample. Leaf’s phenolic content and antioxidant activity were positively correlated, while that of the stem were insignificant.
Keyword: Pupuk, Nutrisi tanaman, Gandarusa, Fenolik, Aktivitas antioksidan, Antioxidant activity, Fertilizer, Gendarussa, Phenolic, 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.
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