Judul: Optimization of Total Flavonoid Extraction and Antioxidant Activity of Gandarusa Leaf Using Two Half Factorial.
Abstrak: Gandarusa (Justicia gendarussa Burm.F.) memiliki berbagai kandungan senyawa bioaktif dengan kandungan antioksidan tinggi yang umumnya dimanfaatkan sebagai obat herbal. Penelitian ini bertujuan untuk mengetahui kombinasi ekstraksi pelarut terbaik serta pengaruh terhadap beberapa faktor yaitu pH, konsentrasi pelarut, waktu, suhu, serta rasio antara cairan dan padatan menggunakan metode Two-half factorial terhadap kadar flavonoid dan antioksidan pada tanaman gandarusa. Hasil penelitian optimasi ekstraksi metode two half factorial menunjukan bahwa kadar total flavonoid dipengaruhi oleh faktor dengan kontribusi tertinggi yaitu interaksi konsentrasi etanol dan pH. Aktivitas antioksidan DPPH dipengaruhi oleh faktor interaksi suhu, konsentrasi etanol, dan pH serta FRAP dipengaruhi oleh faktor interaksi rasio cairan/padatan, suhu, konsentrasi etanol dan pH. Formula rasio cairan/padatan 10 mL/g, suhu 80°, konsentrasi etanol 80%, dan pH 6 merupakan kondisi yang optimum dalam ekstraksi senyawa flavonoid dan aktivitas antioksidan dengan nilai desirability sebesar yaitu 0,82., Gandarusa (Justicia gendarussa Burm.F.) has various bioactive compounds with high antioxidant content which is commonly used as herbal medicine. This study aimed to determine the best solvent extraction combination and the effect of several factors, namely pH, solvent concentration, time, temperature, and the ratio between liquid and solid using the Two-half factorial method on flavonoid and antioxidant levels in gandarusa plants. The results of the extraction optimization research using the two-half factorial method show that the total flavonoid content was influenced by the factor with the highest contribution, namely the interaction of ethanol concentration and pH. DPPH antioxidant activity was influenced by the interaction factors of temperature, ethanol concentration, and pH and FRAP was influenced by the interaction factors of liquid/solid ratio, temperature, ethanol concentration and pH. The liquid/solid ratio formula of 10 mL/g, temperature 80°, ethanol concentration 80%, and pH 6 was the optimum condition in the extraction of flavonoid compounds and antioxidant activity with a desirability value of 0.82.
Keyword: antioxidant, flavonoid, gandarusa, optimization

Judul: Optimization of Extraction of Phenolic Content and  Antioxidant Activity of Gandarusa (Justicia gendarussa Burm f.) Leaf with  Response Surface Methodology (RSM)
Abstrak: Ektraksi daun gandarusa (Justicia gendarussa Burm f.) dapat dipengaruhi oleh pelarut, suhu, dan waktu ekstraksi. Penelitian ini bertujuan menentukan suhu, waktu, dan konsentrasi pelarut optimum kadar total fenolik dan aktivitas antioksidan ekstrak etanol daun gandarusa dengan metode Respon Surface Methodology (RSM). Parameter uji yang dilakukan terhadap ekstrak daun gandarusa antara lain penentuan kadar total fenolik dengan metode Folin-Ciocalteu serta aktivitas antioksidan DPPH dan FRAP. Variabel bebas yang digunakan dalam desain eksperimen adalah konsentrasi etanol (10%, 50%, dan 90%), suhu (30℃, 45℃, dan 60℃) dan waktu ekstraksi (60, 120, dan 180 menit). Kadar total fenolik menunjukan korelasi yang positif dan signifikan terhadap aktivitas antioksidan FRAP daun gandarusa. Kondisi optimal untuk kadar total fenolik dan aktivitas antioksidan DPPH dan FRAP ekstrak daun gandarusa yaitu pelarut etanol 16,8%; suhu 30℃; dan waktu 180 menit. Nilai prediksi dan nilai verifikasi kadar total fenolik dan aktivitas antioksidan DPPH tidak berbeda secara signifikan., Extraction of gandarusa leaves (Justicia gendarussa Burm f. ) can be affected by solvent, temperature, and extraction time. This study aimed to determine the optimum temperature, time, and concentration of solvents, the total phenolic contents and antioxidant activity of gandarusa leaf ethanol extract by the Response Surface Methodology (RSM). Parameters of the test carried out on the extract of gandarusa leaf include determination of total phenolic contents using the Folin-Ciocalteu method as well as the antioxidant activity of DPPH and FRAP. The independent variables used in the experimental design were ethanol concentration (10%, 50%, and 90%), temperature (30℃, 45℃, and 60℃) and extraction time (60, 120, and 180 minutes). Total phenolic content showed a positive and significant correlation to the antioxidant activity of FRAP gandarusa leaves. Optimal conditions for total phenolic content and antioxidant activity of DPPH and FRAP of gandarusa leaf extract are 16,8% ethanol solvent; temperature 30℃; and time 180 minutes. The predictive value and verification value of the total phenolic content and antioxidant activity of DPPH did not different significantly.
Keyword: Antioxidant activity, gendarussa, independent variables, phenolic, RSM

Judul: Estimating Parameter and the Convergence of Parameter Estimator of Poisson Hidden Markov Model
Abstrak: Model hidden Markov terdiri dari sepasang proses stokastik yaitu proses observasi dan proses yang memengaruhi observasi. Proses stokastik yang memengaruhi observasi ini diasumsikan membentuk rantai Markov dan tidak diamati. Model Poisson hidden Markov (MPHM) adalah salah satu model hidden Markov diskret dan proses observasinya jika diketahui proses yang memengaruhinya diasumsikan menyebar Poisson., A hidden Markov model (HMM) consists of a pair of stochastic processes, that is the observation process and process that affected observation. The stochastic process which causes this observation is assumed to form a Markov chain and is not observed. Poisson hidden Markov models (PHMM) is one of the discrete HMM and the observation process given the cause is assumed having a Poisson distribution.
Keyword: Poisson hidden Markov model, Forward-Backward algorithm, Expectation Maximization algorithm