Judul: Chemometric Analysis of Plant Origin and Polarity Index on Total Phenolics, Flavonoids, and Antioxidant Activity of Caricature Plant (Graptophyllum pictum (L.) Griff.) Extract
Abstrak: Daun ungu (Graptophyllum pictum (L.) Griff.) adalah tumbuhan obat dari Papua Nugini dan Polinesia yang kemudian menyebar ke Indonesia. Asal tanaman, indeks polaritas pelarut, serta total fenolik dan flavonoid diduga memiliki korelasi terhadap aktivitas antioksidan daun ungu. Penelitian dilakukan bertujuan untuk mengetahui besarnya pengaruh asal tanaman, indeks polaritas pelarut, serta total fenolik dan flavonoid terhadap aktivitas antioksidan (DPPH) daun ungu menggunakan analisis PCA. Korelasi rendemen ekstrak daun ungu menghasilkan nilai korelasi Pearson sebesar 0.857 dan nilai p sebesar 0.063 serta nilai korelasi Spearman sebesar 0.872 dan nilai p sebesar 0.054. Dalam komparasi kandungan fitokimia daun ungu, sampel daun ungu asal Thailand tidak memiliki kandungan alkaloid dan glikosida. Berdasarkan kandungan fenolik, flavonoid, dan aktivitas antioksidannya, sampel daun ungu asal Indonesia dan Thailand terbagi menjadi dua jenis yang berbeda., Caricature Plant (Graptophyllum pictum (L.) Griff.) is a medicinal plant from Papua New Guinea and Polynesia which later spread to Indonesia. Plant origin, solvent polarity index, and total phenolics and flavonoids are thought to have a correlation to the antioxidant activity of purple leaves. The aim of this study was to determine the effect of plant origin, solvent polarity index, and total phenolic and flavonoid on the antioxidant activity (DPPH) of caricature plant using PCA analysis. The yield correlation of purple leaf extract resulted in a Pearson correlation value of 0.857 and a p-value of 0.063 and a Spearman correlation value of 0.872 and a p-value of 0.054. In comparison to the phytochemical content of caricature plants, caricature plant samples from Thailand did not contain alkaloids and glycosides. Based on the phenolic content, flavonoids, and antioxidant activity, caricature plant samples from Indonesia and Thailand were divided into two different types.
Keyword: Antioxidant, Flavonoid, Graptophyllum pictum, phenolic, origin, polarity index

Judul: Aktivitas antioksidan dan kandungan kimiawi ekstrak daun wungu (Graptophyllum pictum L. Griff.)
Abstrak: Graptophyllum pictum L. Griff., a plant that originated from Papua and Polynesia, is believed to have antioxidant activity. This study aimed to examine of antioxidant activity and chemical content of Graptophyllum pictum L. Griff. leaves. Also, it was designed to determine the best extracting solvent that provides the highest antioxidant activity. This study used four different solvents, which were the solvent water, ethanol 30%, ethanol 70%, and ethanol 96%. Extracts of each solvent were studied to determine the presence or absence of the antioxidant activity and chemical content by using vitamin C as a comparison. The antioxidant activity of water extract, ethanol 30%, ethanol 70%, and ethanol 96% extract were determined using the DPPH (2,2 diphenyl-1-picryl-hydrazyl) with a spectrophotometer at a wavelength of 517 nm. Phytochemical test showed that water extract, ethanol 30%, ethanol 70%, and ethanol 96% Graptophyllum pictum L. Griff. leaves contain alkaloids and flavonoids. Ethanol 30% and ethanol 70% extract were contained saponin. Ethanol 70% and ethanol 96% extract contained tannins and steroids. Antioxidants activity test (IC50) of four types of solvents showed that the antioxidant activity is not active on four types of solvent used, but ethanol 70% extract of Graptophyllum pictum L. Griff. leaves has a weak antioxidant activity with IC50 of 257.79 ppm. It can be concluded that water, ethanol 30%, ethanol 96% extract Graptophyllum pictum L. Griff. leaf have no antioxidant activity as measured using the DPPH method.
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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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