Judul: Study of biomass characters, content and profile of xanthones derivates, and antioxidant properties of mangosteen fruit’s hulls on the several aspects of agronomy
Abstrak: Research reports about the presence of xanthones compounds in the fruit hull of mangosteen and xanthone bioactivity provides great hope for Indonesia as mangosteen producing countries and is the center of origin of the mangosteen plant to explore utilization. Studies on isolation of types of xanthones and biological activity have been widely reported. However, there is a gap between research of chemical /pharmacological and agronomy fields, so it has not been clearly the known the cultuvation and environmental factors on the mangosteen tree. Xanthones development as industrial materials of phytopharmaca or other natural industry requires cultivation standard to produce the raw material of fruit hull which is determined according to industry standards. To achieve this we need studies on biomass production potential of mangosteen fruit hull, xanthone derivatives and profile, and antioxidant properties in aspects of agronomy. This research aims to study the influence of agroecology of production centers, various stages of fruit development of mangosteen and after the fruit is harvested, a diverse group of fruit quality, and the influence of farming inputs of N, P, K fertilization on biomass production of fruit hull, levels and profiles of xanthone derivates, and antioxidant properties. Research began in 2006 through January 2009. The plant material of the mangosteen fruit from mangosteen population in various centers: Leuwiliang, Bogor; Wanayasa, Purwakarta; Puspahiang, Tasikmalaya; Kaligesing, Purworejo dan Watulimo, Trenggalek. The analysis was conducted in various laboratories at the Department of Agronomy and Horticulture; Laboratory of RGCI, Laboratory of Ecophysiology; Integrated Laboratory, Faculty of Agriculture, IPB; and analytical profile of xanthones with Liquid Chromatography Mass Chromatography (LCMS) at the Institute of Molecular Biology, University of Queensland. The results showed that there are fruit hull varries with production location and different stages of fruit maturity. Production of fruit hull is not affected by cultivation technology. Watulimo mangosteen is the largest fruit size and thick hull, so it have the high hull biomass. During the development of fruit, fruit diameter and fruit weight increased until the fruit was 3 month after anthesis (MAA) and then did not change significantly when entering the final process of maturation, 74.99-75.51 g per fruit. The thickness of fruit hull is different between stage of fruit maturity, the highest is 2 MAA and decrease when the ripening fruit; the weight of the hull increase in accordance with the age of the fruit with the highest weight at 3 MAA that is 51.48 g/ fruit. After the fruit is harvested and stored happen deterioration of physical characteristics of fruit. Grouping of fruit quality based on physical characteristics affect hull thickness, weight of wet hull, dry and weight hull but does not affect the hardness of fruit hull; and also affect chemistry characters namely total soluble solids and vitamin C. Input cultivation of N and K fertilization did not increase the physical characters of the mangosteen fruit. Only posphor fertilization increases fruit weight significantly in both doses 600 and 1200 g P2O5 per tree, with fruit weight range 70.22-73.63 g/fruit. The thickness and weight of the fruit hull biomass increased with fertilization at the doses of
Keyword: Radical scavenger, Garcinia mangostana, Guttiferae, Fruit hull, Xanthones derivate, Xanthones profile, Antioxidant

Judul: Physiological study of hardening and color changes of pericarp in relation to climacteric respiration and moisture content in mangosteen (Garcinia mangostana) after harvest
Abstrak: Mangosteen is a high economic value fruit in Indonesia. The problems encountered are the fruit pericarp quickly harden and the color immediately changed to dark purple-black, and sepals quickly turned into brown in color after harvest, so shelf life is short, especially at room temperature. This research aimed to study the process of change in hardness, pericarp and sepal color, and the sepal freshness of the mangosteen fruit and the factors that influence the physiology and biochemistry during storage. The research consisted of five experiments: (1) hardening physiology of mangosteen pericarp, (2) effect of exogenous ethylene and storage temperature on quality changes of mangosteen, (3) effects of 1-methylcyclopropene (1-mcp) and storage temperature on hardening of and color change of pericarp of mangosteen, (4) Effect of cytokinin and CoSO4 on physical quality of mangosteen during cool storage, and (5) Effect of coating material and cytokinin CPPU (N-(2-chloro-4-pyridyl)-N-phenylurea (Forchlorfenuron)) on the quality of mangosteen on cool storage. The results showed that the peak rate of ethylene production one day earlier than the respiration climacteric. The peak rate of ethylene production occurred on day 11 while the respiration climacteric peak occurred on day 12. Climacteric respiration will lead to biochemical changes in the mangosteen fruit pericarp, such an increase in protein content, increased activity of the enzyme phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), and peroxidase (POD), and increasing the amount of lignin. Pericarp hardening occured due to water content decrease in the mangosteen and increased content of lignin. Fruit stored at a temperature of 15oC can last up to 28 days after treatment (DAT). Whereas fruit stored at room temperature only last up to 14 DAT. Mangosteen fruit stored at a temperature of 15oC had lower level of resistance and hardness. had a higher water content, lower weight loss, slower color change, and had a higher total soluble solids (TSS) and titratable acidity (TA). Exogenous ethylene treatment did not provide a marked influence on all the variables observed, which means that the mangosteen fruit wass less sensitive to exogenous ethylene treatment. 1-MCP treatment at various doses did not prolong the shelf life of the mangosteen fruit. This treatment is consistent in both room temperature and at a temperature of 15oC. 6% beeswax better reduce weight loss than other types of coating materials.
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Judul: Kriteria Osilasi Untuk Pertidaksamaan Diferensial Taklinear Orde Dua
Abstrak: dimana pertidaksamaan dibatasi pada suatu selang [T,oo) dengan T?:O, aCt) kontinu pada selang [0,00) dan j(u) mempunyai turunan pertarna yang kontinu pada selang (-00,00) dengan uj(u) >0 untuk u;"O. Dengan menggunakan Asumsi A dan Asurnsi B, diperoleh beberapa teorerna ten tang kriteria osilasi untuk pertidaksamaan diferensial taklinear orde dua.
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