Judul: Stability of Three Genotypes of Gandarusa at Three Planting Locations based on Total Phenolic Content and Antioxidant Activity
Abstrak: Gandarusa (Justicia gendarussa Burm. f.) adalah tanaman herbal yang dapat dikembangkan potensinya berdasarkan stabilitas genotipenya. Penelitian ini bertujuan menyeleksi tiga genotipe dengan penanaman multilokasi (Bogor, Cianjur, dan Sukabumi) berdasarkan parameter kadar total fenolik dan aktivitas antioksidan metode DPPH dan FRAP. Sampel diekstraksi menggunakan etanol proanalisis. Kadar total fenolik diuji menggunakan metode Follin-Ciocalteu. Aktivitas antioksidan diukur menggunakan metode DPPH dan FRAP. Data hasil pengukuran dianalisis menggunakan uji Scott-Knott dan AMMI-2. Hasil biplot AMMI-2 menunjukkan bahwa genotipe G2 (batang hitam) dapat beradaptasi secara spesifik pada lokasi Cianjur, sedangkan genotipe G1 (batang hijau) dan G3 (daun putih) tidak spesifik pada satu lokasi tertentu. Lalu, tidak ada genotipe yang stabil pada semua lokasi (Bogor, Cianjur, dan Sukabumi), sehingga diperlukan penelitian lebih lanjut untuk pengembangan genotipe gandarusa lain yang stabil di berbagai lokasi berdasarkan kandungan total fenolik dan kapasitas antioksidan (DPPH dan FRAP)., Gandarusa (Justicia gendarussa Burm. f.) is a herbal plant that can be developed based on its genotypic stability. This study aims to select three genotypes with multi-location plantings (Bogor, Cianjur, and Sukabumi) based on parameters of total phenolic content and antioxidant activity. Samples were extracted using ethanol proanalysis. Total phenolic levels were tested using the Follin-Ciocalteu method. Antioxidant activity was measured using the DPPH and FRAP methods. The results were analyzed using the Scott-Knott and AMMI-2 tests. The results of the AMMI-2 biplot showed that genotype G2 (black stem) can adapt specifically to the Cianjur location, while genotypes G1 (green stem) and G3 (white leaves) are not specific to one particular location. Then, there is no stable genotype at all locations (Bogor, Cianjur, and Sukabumi), so further research is needed to develop other willow genotypes that are stable in various locations based on total phenolic content and antioxidant capacity (DPPH and FRAP).
Keyword: antioxidant, gandarusa, multilocation test, phenolic, stability of genotype

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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