Judul: Design of Gendarussa Fermentation by  Aspergillus tamarii with Response on Antioxidant Capacity, Total Flavonoids and  Phenolics
Abstrak: Tanaman obat di Indonesia sangat berlimpah sehingga berpotensi dijadikan bahan baku obat, salah satunya gandarusa (Justicia gendarussa Burm F.). Gandarusa merupakan tanaman obat yang termasuk ke dalam kelompok tanaman perdu yang memiliki potensi sebagai antioksidan. Potensi tersebut disebabkan adanya senyawa metabolit sekunder seperti fenolik dan flavonoid. Aspergillus tamarii adalah fungi yang berfilamen sehingga dipercaya mampu meningkatkan senyawa metabolit sekunder melalui proses fermentasi media padat. Tujuan penelitian ini untuk mendapatkan desain formula fermentasi pada gandarusa oleh A.tamarii dengan respon kapasitas antioksidan, kadar total fenolik (TPC) dan flavonoid (TFC). Desain fermentasi dilakukan dengan menggunakan software Design Expert metode two half level factorial. Hasil penelitian menunjukkan faktor fermentasi yang berpengaruh terhadap TPC, TFC, kapasitas antioksidan 2,2- diphenyl-1-picrylhydrazyl (DPPH) dan ferric reducing antioxidant power (FRAP) adalah waktu, suhu, dan konsentrasi inokulum. Solusi desain fermentasi gandarusa yang didapat waktu fermentasi 14 hari, suhu fermentasi 45 ˚C, kelembaban 2 mL, dan konsentrasi inokulum 100%., The medicinal plants in Indonesia are abundant and have the potential to be used as raw materials for medicine production, one of which is gendarusa (Justicia gendarussa Burm F.). Gendarusa is a medicinal plant that belongs to the group of perennial plants and has the potential to be an antioxidant. This potential is due to the presence of secondary metabolites such as phenolics and flavonoids. Aspergillus tamarii is a filamentous fungus believed to be capable of increasing secondary metabolite compounds through solid-state fermentation. This research aimed to obtain a fermentation formula design for gendarusa by A.tamarii with response variables of antioxidant capacity, total phenolic content (TPC), and total flavonoid content (TFC). The fermentation design was conducted using the Design Expert software with a two-half-level factorial method. The research results showed that the fermentation factors affecting TPC, TFC, 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant capacity, and ferric-reducing antioxidant power (FRAP) are time, temperature, and inoculum concentration. The fermentation design solution for gendarusa obtained a fermentation time of 14 days, a fermentation temperature of 45 ˚C, a moisture content of 2 mL, and an inoculum concentration of 100%.
Keyword: antioksidan, Aspergillus tamarii, Design Expert, fermentasi media padat, gandarusa

Judul: Optimization of Extraction for Total Phenolics and Highest  Antioxidant Capacity in Gandarusa Using Two-Level Half Factorial Design
Abstrak: Gandarusa (Justicia gendarussa Burm. f.) telah digunakan sebagai obat tradisional dan dilaporkan memiliki senyawa fitokimia dan aktivitas antioksidan yang tinggi. Penelitian ini bertujuan untuk mengukur pengaruh perbedaan kondisi ekstraksi berdasarkan rasio cairan terhadap padatan, suhu, konsentrasi pelarut, waktu, dan pH tanaman gandarusa dengan two level half factorial design terhadap produksi metabolit sekunder dan kapasitas antioksidannya. Sampel diekstraksi sesuai dengan desain two level half factorial. Kandungan fenolik, kapasitas antioksidan DPPH dan FRAP tertinggi didapat oleh run-13 berturut-turut sebesar 28,15 mg GAE/g, 54,19 μmol TE/g, dan 218,73 μmol TE/g. Desain two level factorial digunakan untuk menentukan faktor yang signifikan terhadap ekstraksi kadar fenolik total, serta kapasitas antioksidan DPPH dan FRAP. Faktor suhu berperan signifikan (< 0,05) terhadap kadar fenolik total. Sedangkan pada kapasitas antioksidan DPPH didapatkan bahwa faktor cairan terhadap padatan dan pH berperan signifikan (< 0,05). Pada FRAP didapatkan bahwa faktor cairan terhadap padatan menjadi faktor yang berperan signifikan (< 0,05). Kata kunci: antioksidan, factorial, gandarusa, cairan terhadap padatan, suhu, Gandarusa (Justicia gendarussa Burm. f.) is often used as a traditional medicine and is reported to contain high levels of phytochemical compounds and antioxidant activity. This study aimed to measure the influence of different extraction conditions based on liquid to solid ratio, temperature, solvent concentration, time, and pH of gandarusa plant on the production of secondary metabolites and antioxidant capacity using a two-level half factorial design. Samples were extracted according to the two-level half factorial design. The highest phenolic content, DPPH and FRAP antioxidant capacity were obtained from run 13, with values of 22.75 mg GAE/g, 43.36 μmol TE/g, and 166.72 μmol TE/g, respectively. A two-level factorial design was used to determine the significant factors affecting the extraction of total phenolic content, DPPH antioxidant capacity, and FRAP antioxidant capacity. Temperature was found to have a significant effect (<0.05) on the total phenolic content. Meanwhile, for DPPH antioxidant capacity, the liquid to solid ratio and pH was found to be the significant factor (<0.05). In FRAP, it was found that the liquid to solid factor was a significant factor (<0.05). Keyword: antioxidant, factorial, gandarusa, liquid to solid, temperature
Keyword: antioxidant, factorial, gandarusa, liquid to solid, temperature

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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