Judul: Penentuan Total Fenolik, Flavonoid, dan Aktivitas Antioksidan Ekstrak Kulit Kayu Mahoni (Swietenia Macrophylla King) pada Berbagai Konsentrasi Etanol.
Abstrak: Pohon mahoni (Swietenia Macrophylla King) banyak ditemukan di dataran tinggi di Indonesia dan umumnya digunakan sebagai obat dan pestisida alami. Penelitian terdahulu sudah dilakukan mengenai aktivitas antioksidan dari berbagai macam pelarut, namun demikian belum diketahui pengaruh perbedaan konsentrasi pelarut etanol terhadap kandungan senyawa fenolik, flavonoid, dan aktivitas antioksidan kulit kayu mahoni. Penelitian ini bertujuan untuk menganalisis pengaruh perbedaan konsentrasi pelarut etanol terhadap senyawa metabolit sekunder dan aktivitas antioksidan. Kulit kayu mahoni diekstraksi dengan metode maserasi menggunakan pelarut air dan beberapa konsentrasi etanol (30%, 50%, 70%, dan 96%). Penentuan kadar total fenolik dan flavonoid menggunakan metode spektrofotometri, dan aktivitas antioksidan diukur menggunakan metode 1,1- diphenyl-2-picrylhydrazyl (DPPH). Hasil penelitian menunjukkan bahwa pelarut etanol 70% menghasilkan kadar total fenolik terbesar (123,16 mg GAE/g), sedangkan kadar total flavonoid terbesar dari etanol 50% (8,40 mg QE/g), dan aktivitas antioksidan terbesar terdapat pada pelarut air (27,22 µmol TE/g).
Keyword: antioksidan, DPPH, kulit kayu, mahoni

Judul: Identifikasi dan Potensi Antioksidan Flavonoid Kulit Kayu Mahoni (Swietenia macrophylla King)
Abstrak: Mahogany bark as wood processing industrial waste has not widely used compared to other parts of mahogany. This research was conducted to identify the flavonoids from mahogany bark and its role as an antioxidant. Antioxidant activity of mahogany bark’s extract was measured by using two methods namely diphenil-1.1-2-picrylhydrazyl (DPPH) method and tiobarbituric acid (TBA) method. Identification of flavonoids (quersetin) was performed by using HPLC and TLC. Antioxidant activity of flavonoids (quersetin) was measured by using DPPH method.Inhibition activity of mahogany bark’s extract on DPPH method for the extraction of methanol, n-hexane, diethyl ether, ethyl acetate, vitamin E (positive control) and water at concentrations of 50 ppm are respectively for 81.33%, 12.74%, 23:40%, 65.54 %, 30.42%, and 68.04%. The inhibition activity of mahogany bark’s extract on TBA methods for methanol fraction 200, 100, 50 ppm was 59.81%, 59.02%, 58.96%. Extraction of water 200, 100, 50 ppm was 54.65%, 49.01%, 43.09%. Vitamin E 200, 100, 50 ppm was 40.91%, 36.48%, 27.15%. Kuersetin content in the sample is 16 mg/100g sample. Inhibition activity of antioxidants on kuersetin as 50, 100, and 200 ppm for 87.2%, 89.1%, 92.8%.
Keyword: 

Judul: Implementasi Space Time Composite (STC) Data Model Menggunakan Model Data Relasional
Abstrak: The data model is a concept that describes the data stored in the database and the relationship between the data to the user in logic. Development of data models is very important in the design of the database as the basis of the stage of database design to be made. This study aims to apply the concept of Space Time Composite (STC) on the Model Data storage vector data types that can store enough information and describes the process of drafting objects and objects spatiotemporal evolution over time. From the results of the test queries on the data model that have been created, queries in a system are acquired that can help display the information preparation of objects from time to time and know the history of the object polygon and arc that has undergone changes in topology.
Keyword: