Judul: Produksi Xilitol dari Hidrolisat Limbah Tandan Kosong Sawit oleh Candida tropicalis.
Abstrak: Limbah padat terbesar yang dihasilkan dari perkebunan kelapa sawit salah satunya adalah tandan kosong kelapa sawit (TKKS). Limbah tersebut hingga saat ini dimanfaatkan sebagai pupuk organik namun pemanfaatan tersebut belum maksimal. Limbah TKKS dengan komponen utama hemiselulosa, selulosa, dan lignin dapat dihidrolisis menjadi xilosa dan dikonversi menjadi produk xilitol yang memiliki nilai jual tinggi. Xilitol merupakan gula alkohol yang memiliki manfaat untuk mencegah kerusakan gigi, memiliki nilai kalori dan nilai glikemik yang rendah sehingga aman bagi penderita diabetes. Penelitian ini bertujuan untuk memproduksi xilitol dari limbah TKKS dengan pemberian arabinosa sebagai kosubstrat pada sel Candida tropicalis. Xilosa dihidrolisis secara kimiawi menggunakan asam dan rendemen yang dihasilkan diukur dengan metode DNS, nilai rendemen xilosa tertinggi yaitu 4.93%. Xilitol yang dihasilkan diukur dengan ELISA Reader menggunakan kit D-sorbitol Colorimetric Assay pada panjang gelombang 540 nm dan waktu inkubasi selama 30 menit. Kadar xilitol tertinggi yang dihasilkan pada sampel TKKS sebesar 13.559%. Penambahan ko-substrat arabinosa tertinggi diperoleh pada arabinosa 5% di waktu fermentasi 8 jam.
Keyword: Arabinosa, C. tropicalis, tandan kosong kelapa sawit, xilitol

Judul: Optimasi Konsentrasi Arabinosa sebagai Ko-substrat untuk Produksi Xilitol oleh Sel Amobil Candida tropicalis
Abstrak: This research was carried out to investigate xylitol production by Candida tropicalis immobilized cells under two sets condition, which were addition of arabinose as a co-substrate and its fermented on sugar mixed medium. Ratio xylose to arabinose was used at the range 6:1-6:3% (xylose 30 g/L and arabinose 5-15 g/L). Sugar mixed medium variation which used in this research were xylose and glucose; xylose and arabinose; and also xylose, glucose, and arabinose, respectively. Candida tropicalis cells entrapped in Ca-alginate and incubated in batch fermentation on 100 rpm rotary shaker at 30˚C for 96 hours. Xylitol produced by cells were measured using spectrophotometer and by D-sorbitol/Dxylitol enzymatic assays. The results revealed that addition of arabinose at the range 6:1-6:3% could increased xylitol production (3.11-5.90 g/L). The highest volumetric rate of xylitol production (0.06 g/L h) and yield product (0.20 g xylitol produced /g xylose consumed) were achieved at ratio 6:3%. Contrary with glucose in fermentation medium could decreased xylitol production of 20% compared with control medium. This negative effect of glucose was annulled by adding arabinose in sugar mixed medium containing xylose, glucose, and arabinose can reached xylitol production for 4.2 g/L.
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: