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: 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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