Judul: Aktivitas Antioksidan Lignin dari Lindi Hitam Kraft Berbahan Baku Kayu Eukaliptus
Abstrak: Kraft black liquor is produced from kraft process as byproduct. Lignin is the highest component in this black liquor, approximately 46% of the total solid. Lignin can be isolated from black liquor by precipitation using H2SO4 20% (w/v) until pH of 2. Klason method was used to purify lignin through hydrolysis using H2SO4 72% (w/v) to eliminate polysaccharides. The observed parameters were yield, molecular weight, phenolic hydroxyl content, functional groups analysis by infrared spectrophotometer, and testing the antioxidant activity of lignin. The phenolic hydroxyl content of 2.40%, respectively. Vibration of aromatic ring and deformation of C-H indicated that qualitatively lignin was present. Antioxidant activity of lignin was tested with DPPH method (1,1-diphenyl-2-picrylhydrazyl) as a free radical, measured using UV-Vis spectrophotometer at wavelength 515 nm. BHT (buthylated hydroxyltoluene) was used as a positive control. Percentage inhibition was plotted as a lignin concentration function. From the resulting graph can be determined lignin concentration required to reach 50% of percentage inhibition as the IC50. The IC50 was 43 ppm, which is less than 50 ppm, meaning that the eucalypt kraft lignin is potential as an antioxidant.
Keyword: 

Judul: Aktivitas Antioksidan Lignin dari Lindi Hitam Kraft Berbahan Baku Kayu Acacia mangium
Abstrak: The use of black liquor, spent liquor produced from pulp processing, can be increased through isolation and purification to produce various useful products. One of the components in the liquor is lignin. Lignin was isolated from black liquor by precipitation using H2S04 20%. Lignin has potential application as an antioxidant. Phenolic hydroxyl groups in lignin can scavenge the free radicals. In this study, antioxidant activity of lignin, which is isolated from black liquor of Acacia mangium wood as the raw material, was examined by diphenyl picrylhydrazyl (DPPH) method. Lignin would scavenge the DPPH free radicals and change the color from purple to pale yellow of diphenyl picrylhydrazine. The change of color intensity was measured by ultraviolet-visible spectrophotometer. The result showed that lignin had strong antioxidant activity with 50% inhibition concentration (IC50) value of 18 ppm, higher than 3,5-di(t-butyl)-4- hydroxytoluene with IC50 value of 1880 ppm. Antioxidant activity of lignin was increasing with the increasing phenolic hydroxyl content and the decreasing lignin molecular weight
Keyword: 

Judul: Implementation of Spatio-Temporal Change Query in Relational Database.
Abstrak: Geographic object changes in various views. Object changes are recorded using a model of static storage. No historical connection between old version data and new version data has been built. For that, a storage model of spatio-temporal queries that can analyze spatio-temporal changes has been developed. The object changes the geometry are grouped according to the taxonomy of Spatio-Temporal Pattern Change. This research has been able to apply the query patterns change including born, expand, merge, contract, split, normal and die. This query based on geometric (area) changes. The implementation of spatio-temporal change queries represents an object changes continuously with easy, change detection is done by comparing two versions of data. Keyword: spatio-temporal change query, spatio-temporal change pattern.
Keyword: