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: 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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