Judul: Likuifikasi Onggok dan Konversinya Menjadi Ester Poliol Oleat sebagai Pengawabusa.
Abstrak: Onggok merupakan biomassa yang mengandung selulosa dan pati. Onggok dilikuifikasi dengan etilena glikol dalam suasana asam menghasilkan poliol. Poliol kemudian diesterifikasi dengan asam lemak dengan ragam nisbah massa poliol:asam lemak, yaitu 1:1, 1:2, 1:3, dan 1:4. Ester poliol dari onggok diuji efektivitasnya sebagai pengawabusa (defoamer). Likuifikasi onggok menghasilkan rendemen likuifikasi 91.65%, dan bilangan hidroksil 613.5 mg KOH/g. Spektrum inframerah onggok yang terlikuifikasi menunjukkan vibrasi ulur hidroksil pada bilangan gelombang 3288 cm-1. Setelah esterifikasi, tidak terdapat serapan inframerah untuk vibrasi gugus hidroksil dan terdapat pergeseran vibrasi karbonil menjadi 1738 cm-1 sehingga dapat disimpulkan poliol telah teresterifikasi. Ester poliol oleat dengan bilangan ester terbesar adalah pada nibah massa 1:1, yakni 206 mg KOH/g. Ester poliol oleat dengan efektivitas busa paling baik ialah pada nisbah massa 1:1 dan 1:3 dengan konsentrasi optimum masing-masing 3200 mg/L dan 4800 mg/L.
Keyword: asam oleat, esterifikasi, likuifikasi, onggok, poliol

Judul: Sintesis dan Pencirian Ester dari Asam Oleat dan Poliol Berbasis- Onggok
Abstrak: Onggok is a solid waste from tapioca industry that contains cellulose. Polyhydroxyl compounds (polyol) can be produced through liquefaction of cellulose. Cellulose liquefaction was carried out in ethylene glycol medium catalyzed by sulfuric acid, at 150 °C over 4 h, with 98.72% of yield. The polyol was esterified with oleic acid and sulfuric acid as catalyst to synthesize a nonionic surfactant. Esterification was carried out at 140 °C in 4 h, with oleic acid-polyol ratios of 1:2, 1:1, and 2:1. The free fatty acid contents and acid values of the esterification products were 23.07, 43.05, 60.97% and 32.67, 60.97, 86.34 mg KOH/g, respectively. Infrared spectrum of the ester products showed a C=O stretching band in wavenumber region of 1750–1715 cm-1, which was not present in polyol, but in oleic acid (1720–1680 cm-1). Intensity of O-H stretching band in ester products was weaker than in polyol spectrum (around 3400 cm-1) and C-H stretching band of the ester products in 2950–2800 cm-1 was originated from oleic acid.
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Judul: Indexing Spatio-Temporal Pada Data Hotspot
Abstrak: The spatial information of hotspot is always changing over time. The recording of these changes makes it necessary to add dimension of time (temporal) into database. The database which is capable to store spatial and temporal information is known as spatiotemporal database. This database is bigger than a normal database because it stores all versions of an object over time and not allowed data to be physically deleted. A large database size causes it’s search time increases. It makes an access structure is needed in spatiotemporal database. Indexing is one of the access structure applied in the spatiotemporal database that accelerates data searching process. Spatiotemporal indexing method consists of two parts namely spatial indexing which is based on geographical information, and temporal indexing which is based on data timing information. The process of hotspot data indexing will be done in this research by using R-Tree approach for spatial data and Change Temporal Index (CTI) for temporal data. R-Tree is a hierarchical, height-balanced external memory data structure for multidimensional object. The hierarchical of R-Tree based on list of administrative such as regency, provinces and island. Change Temporal Index makes indexed data based on temporal side like valid time. CTI keeps valid data in current database and previous data according to interval valid time in historical database. This research is expected to accelerate the retrieving process in spatiotemporal databases. Spatial indexing makes searching faster up to 70%, temporal indexing makes searching faster up to 35% and spatiotemporal indexing makes searching faster than without indexing up to 50%.
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