Judul: Total Phenolic and Flavonoids Content, and Antioxidant Activity of Mango Peel Extract of Cengkir Variety based on Simplisia’s Particle Size
Abstrak: Kulit mangga diketahui memiliki senyawa polifenol sehingga berpotensi sebagai antioksidan. Aktivitas antioksidan pada kulit mangga dapat ditingkatkan dengan memperkecil ukuran partikel simplisia. Penelitian ini bertujuan menentukan pengaruh ukuran partikel simplisia terhadap kadar total fenolik dan flavonoid, serta aktivitas antioksidan ekstrak kulit mangga varietas cengkir. Penelitian ini menggunakan dua ukuran partikel simplisia yang berbeda. Kulit mangga diekstraksi dengan cara maserasi menggunakan pelarut air. Kadar total fenolik dan flavonoid, serta aktivitas antioksidan dari masing-masing ekstrak diukur secara kolorimetri. Hasil penelitian menunjukkan kadar total fenolik ekstrak 40 mesh (≤420 x 103 nm) dan ekstrak nanopartikel (597 nm) kulit mangga varietas cengkir berturut-turut sebesar 156,61 ± 2,32 mg GAE/g bobot kering dan 170,42 ± 2,84 mg GAE/g bobot kering. Kadar total flavonoid ekstrak 40 mesh dan ekstrak nanopartikel kulit mangga varietas cengkir berturut-turut sebesar 115,76 ± 0,96 mg QE/g bobot kering dan 132,15 ± 1,05 QE/g bobot kering. Ekstrak 40 mesh kulit mangga varietas cengkir termasuk antioksidan sedang, sedangkan ekstrak nanopartikel kulit mangga varietas cengkir termasuk antioksidan kuat. Ukuran partikel simplisia secara positif memengaruhi kadar total fenolik dan flavonoid, serta aktivitas antioksidan kulit mangga varietas cengkir., Mango peel is known to contain polyphenol compounds so its potential as antioxidant. The antioxidant activity of mango peel can be increase by reducing the simplisia’s particle size. This research was aimed to determine the effects of simplisia’s particle size on total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of cengkir mango peels. This research used two differents simplisia’s particle size. Mango peel was extracted by maceration using water as a solvent. TPC, TFC, and antioxidant activity of each extract were measured in colorimetric way. The result showed that TPC of 40 mesh (≤420 x 103 nm) extract and nanoparticle (597 nm) extract of cengkir mango peels were 156,61 ± 2,32 mg GAE/g dry weight and 170,42 ± 2,84 mg GAE/g dry weight, respectively. The TFC of 40 mesh extract and nanoparticle extract of cengkir mango peels were 115,76 ± 0,96 mg QE/g dry weight and 132,15 ± 1,05 mg QE/g dry weight, respectively. The 40 mesh extract of cengkir mango peels were moderate antioxidant, while the nanoparticle extract of cengkir mango peels were strong antioxidant. Simplisia’s particle size positively affects the TPC, TFC, and antioxidant activity.
Keyword: antioxidant, cengkir mango peels, flavonoid, nanoparticle, phenolic

Judul: Antioxidant Activity and Total Phenolic Content of Cinnamon Bark (Cinnamomum burmannii) from Jambi based on Simplisia's Particle size
Abstrak: Kulit kayu manis mengandung senyawa polifenol yang berpotensi sebagai antioksidan dan dapat ditingkatkan dengan memperkecil ukuran partikel simplisia. Penelitian ini bertujuan menentukan pengaruh ukuran partikel simplisia terhadap rendemen ekstrak, nilai kadar total fenolik, dan aktivitas antioksidan kulit kayu manis asal Jambi. Kayu manis diekstraksi menggunakan pelarut etanol 70%, pengujian aktivitas antioksidan dilakukan menggunakan uji DPPH dengan nilai IC50. Hasil rendemen simplisia nanopartikel lebih tinggi yakni sebesar 38,36% dari kedua sampel lainnya. Hasil uji aktivitas antioksidan sampel simplisia nanopartikel lebih kuat yakni sebesar 34,56 ± 0,72 μg/ml daripada kedua sampel lainnya. Kadar total fenolik sampel simplisia nanopartikel lebih tinggi daripada sampel lainnya yakni sebesar 60,14 ± 3,66 mg GAE/g bobot kering. Hasil pengujian menunjukkan hasil yang berbeda nyata (p<0,05). Korelasi diantara nilai total fenolik dengan nilai IC50 DPPH sangat kuat dan bernilai negatif. Semakin tinggi kadar total fenolik maka semakin kecil nilai IC50, sehingga semakin baik aktivitas antioksidan yang dimiliki pada sampel. Ukuran simplisia terbukti secara positif mempengaruhi hasil rendemen ekstrak, nilai kadar total fenolik dan aktivitas antioksidan kulit kayu manis., Cinnamon bark is known contains polyphenol compounds which have potential as antioxidants and can be increased by reducing the size of the simplisia particles. This research was aimed to determine the effects of simplisia’s particle size on extract yield, total phenolic levels, and antioxidant activity of cinnamon bark from Jambi. Cinnamon was extracted using 70% ethanol solvent, antioxidant activity testing was performed using DPPH test with IC50 value. The yield of simplisia nanoparticles was higher at 38.36%. The antioxidant activity test results of the nanoparticle simplisia samples were stronger, 34.56 ± 0.72 μg/ml than the. The TPC of the nanoparticle simplisia samples was higher than the other samples, 60.14 ± 3.66 mg GAE/g dry weight. The test results showed significantly different results (p<0.05). The correlation between the total phenolic value and the IC50 DPPH value is very strong and negative. The higher the total phenolic content, the lower the IC50 value, so the better the antioxidant activity in the sample. The simplisia size was proven to positively affect the total phenolic content and antioxidant activity of cinnamon bark.
Keyword: antioksidan, fenolik, kulit kayu manis, nanopartikel

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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