Judul: Optimasi Fermentasi Justicia gendarussa Burm.f. oleh Aspergillus oryzae Berdasarkan Respon Kapasitas Antioksidan, Total Fenolik dan Flavonoid
Abstrak: Gandarusa mempunyai aktivitas antioksidan yang diduga berasal dari senyawa flavonoid dan fenolik. Faktor-faktor yang mempengaruhi hasil fermentasi padat oleh Aspergillus oryzae belum diketahui, sehingga diperlukan penelitian mengenai optimasi fermentasi untuk memaksimalkan potensi tersebut. Proses fermentasi diberi perlakuan seperti suhu, waktu, konsentrasi inokulum, dan kelembaban. Faktor suhu dan kelembaban mempengaruhi proses selama pertumbuhan jamur pada media, parameter tersebut tidak lepas dari parameter waktu fermentasi. Semakin lama waktu fermentasi maka kandungan total fenolik dan kapasitas antioksidannya semakin tinggi. Fermentasi tanaman gandarusa dengan Aspergillus oryzae mengalami peningkatan nilai kandungan total fenolik dan flavonoid, kapasitas antioksidan metode DPPH dan FRAP dibandingkan dengan tanaman gandarusa yang tidak difermentasi. Rancangan fermentasi optimal yang diperoleh adalah, waktu fermentasi 14 hari, suhu fermentasi 45°C, kelembaban 20% total kadar air, dan konsentrasi inokulum 20%., Gandarusa has antioxidant activity that is believed to come from flavonoid and phenolic compounds. Factors influencing solid-state fermentation outcomes by Aspergillus oryzae are not yet known, so research is needed to optimize fermentation to maximize this potential. The fermentation process involves variables such as temperature, time, inoculum concentration, and humidity. Temperature and humidity factors affect the process during fungal growth in the media, and these parameters are closely linked to fermentation time. The longer the fermentation time, the higher the total phenolic content and antioxidant capacity. Fermentation of Gandarusa plants with Aspergillus oryzae leads to increased total phenolic and flavonoid content, as well as antioxidant capacity using DPPH and FRAP methods compared to non-fermented Gandarusa plants. The optimal fermentation design obtained includes a fermentation time of 14 days, fermentation temperature of 45°C, humidity of 20% total moisture content, and inoculum concentration of 20%.
Keyword: antioxidant, Aspergillus oryzae, Justicia gendarusssa, phenolic, solidstate fermentation

Judul: Aktivitas Antioksidan Hasil Fermentasi Media Padat Berbasis Gandarusa (Justicia gendarussa Burm. f.) oleh Aspergillus oryzae
Abstrak: Gandarusa menghasilkan metabolit sekunder yang memiliki potensi sebagai senyawa antioksidan. Penelitian ini bertujuan menentukan aktivitas antioksidan serta menentukan pelarut terbaik untuk mengekstraksi hasil fermentasi media padat berbasis kedelai dan gandarusa oleh Aspergillus oryzae. Kadar total fenolik dan flavonoid tertinggi diperoleh pada ekstrak etil asetat fermentasi campuran media kedelai dan gandarusa (1:1) serta gandarusa (16,668 mg GAE/g ekstrak dan 21,822 mg QE/g ekstrak). Aktivitas antioksidan DPPH dan ABTS tertinggi diperoleh pada ekstrak metanol fermentasi gandarusa dan campuran kedelai dan gandarusa (1:1) (4,964 mg TE/g ekstrak dan 63,35 mg TE/g ekstrak). Aktivitas antioksidan FRAP tertinggi diperoleh pada ekstrak etil asetat gandarusa tanpa fermentasi dengan nilai 106,004 mg TE/g ekstrak. Kadar total fenolik dan flavonoid menunjukkan korelasi positif dengan aktivitas antioksidan FRAP dan ABTS namun tidak berkorelasi dengan aktivitas antioksidan DPPH. Pelarut terbaik untuk mengekstraksi hasil fermentasi media padat berbasis kedelai dan gandarusa yaitu metanol., Gandarusa produce many secondary metabolites that have potential as antioxidant. This research aims to measured the activity of antioxidant and determining the best solvent to extract soybean and gandarusa-based solid media fermentation by Aspergillus oryzae. The highest phenolic and flavonoid content was obtained by ethyl acetate extract of fermented soybean-gandarusa (1:1) and gandarusa, respectively (16,668 mg GAE/g extract, 21,822 mg QE/g extract). The highest antioxidant activity of DPPH and ABTS methods was obtained by methanol extract of fermented gandarusa and soybean-gandarusa (1:1), respectively (4,964 mg TE/g extract, 63,35 mg TE/g extract). The highest activity antioxidant of FRAP method was found in ethyl acetat extract of non-fermented gandarusa (106,004 mg TE/g extract). Total phenolic and flavonoid content had a strong positive and significant correlation with antioxidant activity of FRAP and ABTS methods, while there is no significant correlation with antioxidant activity of DPPH method. The best solvent to extract secondary metabolite of fermented soybean and gendarussa-based solid media is methanol.
Keyword: antioxidant, flavonoid, gandarusa, phenolic, solid-state fermentation

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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