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: 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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