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: Flavonoid Content and Antioxidant of Gandarusa (Justicia gendarussa Burm. f.) Methanol Extract Cultivated with Manure and NPK
Abstrak: Gandarusa (Justicia gendarussa Burm. f.) merupakan salah satu tanaman obat yang berpotensi sebagai antioksidan karena adanya kandungan metabolit sekunder. Kandungan metabolit sekunder dan antioksidan pada tanaman dapat dipengaruhi oleh kondisi lingkungan tumbuh tanaman tersebut, salah satunya pemberian pupuk. Penelitian ini bertujuan menentukan teknik budidaya yang tepat menggunakan komposisi pupuk kandang dan NPK terhadap tanaman gandarusa, dengan menganalisis kadar flavonoid dan aktivitas antioksidan secara in vitro. Pupuk yang digunakan adalah kombinasi pupuk kandang dan NPK dengan dilakukannya enam perlakuan. Total flavonoid diukur menggunakan metode kuantitatif spektrofotometri, sedangkan aktivitas antioksidan ditentukan menggunakan metode CUPRAC dan ABTS. Hasil menunjukkan pemberian 50% pupuk kandang dan 50% NPK memberikan hasil total flavonoid tertinggi pada daun sebesar 4,5690 mg/g, dan berkorelasi positif serta signifikan terhadap total antioksidan metode ABTS pada daun sebesar 15,089 µmol/g., Gandarusa (Justicia gendarussa Burm. f.) is a medicinal plant that has the potential as an antioxidant due to the presence of secondary metabolites. The content of secondary metabolites and antioxidants in plants can be affected by the environmental conditions where the plants growth, such as application of fertilizers. This research aims to determine the appropriate cultivation technique using the composition of manure and NPK on gandarusa, by analyzing the levels of flavonoids and antioxidant activity with in vitro method. The fertilizers used were a combination of manure and NPK with six treatments. Total flavonoids content was determined quantitative spectrophotometric methods, and the antioxidant activity use CUPRAC and ABTS methods. The results showed the application of 50% manure and 50% NPK gave the highest total flavonoid yields in gandarusa leaves 4,569 mg/g and had a positive and significant correlation with the total antioxidant ABTS method on leaves 15,089 µmol/g.
Keyword: Antioksidan, Flavonoid, Gandarusa, NPK, Pupuk Kandang

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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