Judul: Extraction of Total Anthocyanin Content from Secang Wood Using Ultrasonic Assisted Extraction Method
Abstrak: Kayu secang kaya akan senyawa polifenol seperti antosianin, dikenal memiliki kekuatan antioksidan. Metode ekstraksi yang umum seperti maserasi, seringkali lambat dan memberikan rendemen rendah. Untuk meningkatkan efisiensi, metode Ultrasonic Assisted Extraction (UAE) menjadi alternatif. UAE menggunakan gelombang suara dengan frekuensi di atas pendengaran manusia (≥ 20 kHz) untuk mempercepat proses ekstraksi. Penelitian ini fokus pada evaluasi pengaruh amplitudo dan waktu eksitasi dalam UAE terhadap ekstraksi antosianin total dari kayu secang. Alat UAE yang digunakan adalah Sonicator UP200ST Hielscher dengan daya 200 W dan frekuensi 26 kHz. Percobaan menggunakan rancangan acak lengkap dua faktor yaitu, waktu eksitasi (15 dan 30 menit) dan amplitudo ultrasonik (40, 60, 80%). Parameter yang diamati meliputi kadar air, rendemen, kadar antosianin total, dan aktivitas antioksidan. Sebagai pembanding, metode maserasi dilakukan pada suhu 35°C selama 7 jam. Hasil menunjukkan UAE efektif meningkatkan rendemen, kadar antosianin total, dan aktivitas antioksidan dibandingkan maserasi. Meskipun terjadi kenaikan suhu pada amplitudo 60% dan 80%, pengontrol suhu menjaga suhu tetap sekitar 35°C, mengurangi risiko oksidasi antioksidan. Perlakuan terbaik adalah amplitudo 80% dan waktu eksitasi 30 menit, menghasilkan rendemen 17.87%, kadar antosianin total 211,94 ppm, dan aktivitas antioksidan IC50 42,67 ppm. Penerapan UAE meningkatkan rendemen sebesar 5,07-9,39%, kadar antosianin total meningkat 15,47-108,62%, dan aktivitas antioksidan meningkat 8,67-35,53% dari kayu secang. Dengan demikian, UAE terbukti sebagai metode ekstraksi efektif, mempercepat proses dan meningkatkan kualitas ekstrak antioksidan dari kayu secang., Sappan wood rich in polyphenolic compounds such as anthocyanins, is known for its potent antioxidant properties. Common extraction methods, such as maceration, are often slow and yield low extraction efficiency. To enhance efficiency, the Ultrasonic Assisted Extraction (UAE) method becomes an alternative. UAE utilizes sound waves with frequencies above human hearing (≥ 20 kHz) to expedite the extraction process. This study focuses on evaluating the influence of amplitude and sonication time in UAE on the total anthocyanin extraction from sappan wood. The UAE device used was the Sonicator UP200ST Hielscher with a power of 200 W and a frequency of 26 kHz. The experiment employed a completely randomized design with two factors: sonication time (15 and 30 minutes) and ultrasonic amplitude (40, 60, 80%). Parameters observed included moisture content, yield, total anthocyanin content, and antioxidant activity. For comparison, the maceration method was conducted at a temperature of 35°C for 7 hours. Results indicate that UAE effectively improves yield, total anthocyanin content, and antioxidant activity compared to maceration. Despite the temperature increase at amplitudes of 60% and 80%, temperature control maintained the temperature around 35°C, minimizing the risk of antioxidant oxidation. The optimal treatment was an 80% amplitude with a 30-minute sonication time, resulting in a yield of 17.87%, a total anthocyanin content of 211.94 ppm, and antioxidant activity with an IC50 of 42.67 ppm. The application of UAE increased the yield by 5.07-9.39%, the total anthocyanin content by 15.47-108.62%, and antioxidant activity by 8.67-35.53% from sappan wood. Thus, UAE proves to be an effective extraction method, accelerating the process and enhancing the quality of antioxidant extracts from sappan wood.
Keyword: extraction, anthocyanin, antioxidant, sappan wood, ultrasonic

Judul: Effect of Extraction Method on  Yield and Antityrosinase Activity  of Merbau Wood Extract (Intsia bijuga (Colebr.) Kuntze).
Abstrak: Penelitian ini bertujuan untuk menentukan rendemen, aktivitas antitirosinase, dan profil fitokimia ekstrak kayu merbau (KM) dengan berbagai metode ekstraksi. Kayu merbau diekstraksi menggunakan metode maserasi konvensional (MK) dengan perendaman selama 24 jam, magnetic stirer (MS) dengan kecepatan 300 rpm selama 45 dan 60 menit, serta metode ultrasound-assisted extraction (UAE) selama 45 menit dengan amplitudo 65%. Hasil penelitian menunjukkan bahwa interaksi antara metode ekstraksi dan pengulangan ekstraksi berpengaruh terhadap rendemen, aktivitas antitirosinase, dan total fenol. Ekstraksi KM pada UAE-F1 menghasilkan nilai rendemen tertinggi (13,3776±0,308%). Ekstraksi KM pada UAE-F3 menghasilkan aktivitas antitirosinase ( IC50 1,548±0,102 ppm) terkuat dan total fenol (692,86±7,14 mg/g AGE) tertinggi. Hasil ekstraksi dengan metode UAE merupakan kondisi ekstraksi terbaik dengan pengulangan ekstraksi dari F1 hingga F3. Spektrum FTIR pada F1 menunjukkan semua ekstrak terdeteksi memiliki gugus fungsi yang sama yaitu O-H (3800-3000 cm-1) dan C=C (1600- 1475 cm-1). Ekstrak UAE memiliki jumlah gugus fungsi yang paling tinggi., This study aimed to determine the yield, antityrosinase activity, and phytochemical profile of merbau wood extract (KM) with various extraction methods. Merbau wood was extracted using conventional maceration (MK) method with immersion for 24 hours, magnetic stirrer (MS) at 300 rpm for 45 and 60 minutes and ultrasound-assisted extraction (UAE) method for 45 minutes with an amplitude of 65%. The results showed that the interaction between the extraction method and the extraction repetition affected the yield, antityrosinase activity and total phenol. KM extraction with UAE-F1 resulted in the highest yield value (13.3776±0.308%). KM extraction with UAE-F3 resulted in the strongest antityrosinase activity (IC50 1.548±0.102 ppm) and the highest total phenol (692.86±7.14 mg/g AGE). The extraction result using the UAE method was the best extraction condition with the extraction repetition from F1 to F3. The FTIR spectrum at F1 showed that all extracts were detected to have the same functional groups, namely O-H (3800-3000 cm-1 ) and C=C (1600-1475 cm-1). UAE extract has the highest number of functional groups.
Keyword: maserasi, magnetic stirer, total fenol, ultrasound-assisted extraction, maceration, magnetic stirer, total phenolic content, ultrasound-assisted extraction

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
Keyword: