Judul: Evaluasi Kandungan Polifenol dan Kapasitas Peredaman Radikal dari 20 Genotipe Ekstrak Etanol Rimpang Temu Ireng (Curcuma aeruginosa Roxb.)
Abstrak: Temu ireng (Curcuma aeruginosa Roxb.) adalah tanaman rempah yang memiliki berbagai manfaat dan sering digunakan sebagai obat tradisional. Varietas unggul temu ireng untuk dikembangkan sebagai tanaman obat, harus stabil atau dapat tumbuh di berbagai kondisi lingkungan. Penelitian ini dilakukan untuk mengevaluasi kandungan polifenol dan kapasitas peredaman radikal bebas melalui interaksi genotipe oleh lingkungan (GEI) dengan metode DPPH dan TEAC (Trolox Equivalent Antioxidant Capacity) dari 20 genotipe ekstrak etanol rimpang temu ireng yang tumbuh di tiga lingkungan yang terletak di zona agro-ekologis yang berbeda. Hasil analisis AMMI-varians (Additive Main Effect and Multiplicative Interaction - variants) menunjukkan efek signifikan untuk genotipe, lingkungan, dan interaksi genotipe oleh lingkungan. Genotipe stabil di tiga lokasi untuk kandungan polifenol adalah G8, G9, G10, G11, G14, G19, dan G20. Genotipe stabil di tiga lokasi untuk kapasitas peredaman radikal DPPH adalah G5, G10, G15, G18 dan C1 dan untuk kapasitas peredaman radikal ABTS (metode TEAC) adalah genotipe selain G1, G3, G6, G7, G12, G13, G16, C1, C2, dan C3.
Keyword: aditif, AMMI, GEI, TEAC, varians

Judul: Pengaruh Pelarut Ekstraksi Rimpang Temu Ireng Metode Microwave Assisted Extraction Terhadap Kandungan Polifenol dan Kapasitas Antioksidan
Abstrak: Temu ireng (Curcuma aeruginosa) merupakan salah satu tanaman yang mengandung senyawa fenolik berupa flavonoid yang berpotensi sebagai antioksidan alami. Pemilihan pelarut ekstraksi yang tepat merupakan hal yang penting untuk mendapatkan metabolit sekunder berkualitas. Penelitian ini bertujuan menentukan pelarut terbaik untuk mengekstrak rimpang temu ireng berdasarkan kadar fenolik total, kadar flavonoid total, dan kapsitas antioksidan dengan metode 2,2-diphenyl-1-pycrilhidrazil (DPPH) dan Ferric Reducing Antioxidant Power (FRAP). Kadar fenolik total diukur menggunakan metode Folin-Ciocalteu dan kadar flavonoid total diukur menggunakan metode Alumunium Klorida. Sampel diekstraksi dengan metode microwave assisted extraction (MAE) dengan pelarut akuades, etanol 50%, metanol 50%, dan aseton 50%. Hasil penelitian menunjukkan pelarut aseton 50% memiliki kadar fenolik total tertinggi (3,10 mg GAE/g BK), sedangkan pelarut metanol 50% menunjukkan kadar flavonoid total tertinggi (4,10 mg QE/g BK), serta kapasitas antioksidan DPPH (1,28 µmol TE/g BK), dan FRAP (12,21 µmol TE/g BK). Pelarut terbaik dalam mengekstrak senyawa aktif pada rimpang temu ireng adalah metanol 50% karena menghasilkan kadar flavonoid total serta kapasitas antioksidan metode DPPH dan FRAP tertinggi., Curcuma aeruginosa is one of the plants that contain phenolic compounds in the form of flavonoids that have the potential to be natural antioxidants. Choosing the right extraction solvent is essential to obtaining quality secondary metabolites. This study aimed to determine the best solvent to extract black rhizomes based on total phenolic content, total flavonoid content, and antioxidant capacity by DPPH and FRAP methods. The total phenolic content was measured using the Folin-Ciocalteu method and the total flavonoid content was measured using the Aluminum Chloride method. The samples were extracted by microwave assisted extraction (MAE) method with aqueous solvents, 50% ethanol, 50% methanol, and 50% acetone. The results showed that 50% acetone solvent had the highest total phenolic content (3,10 mg GAE/g BK), while 50% methanol solvent showed the highest total flavonoid content (4,10 mg QE/g BK), as well as the antioxidant capacity of DPPH (1,28 µmol TE/g BK), and FRAP (12,21 µmol TE/g BK). The best solvent for extracting the active compounds in the rhizomes of black temu is 50% methanol because it produces the total flavonoid levels and the highest antioxidant capacity of the DPPH and FRAP methods.
Keyword: flavonoid, Antioksidan, Pelarut, Fenolik, Temu ireng

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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