Judul: Urea Enrichment and Paraffin Coating on Onggok-Poliacrylamide Superabsorbent.
Abstrak: Superabsorben disintesis dengan menggunakan polimerisasi pencangkokantaut- silang, dengan onggok sebagai kerangka utama, akrilamida sebagai monomer, amonium persulfat sebagai inisiator, dan metilena bis-akrilamida sebagai penaut-silang. Superabsorben tanpa saponifikasi memiliki daya serap air sebesar 32.35 g/g, yang dengan saponifikasi meningkat menjadi 615.62 g/g. Pengayaan superabsorben dilakukan dengan merendam dalam larutan urea 1000 ppm selama 24 jam. Superabsorben tersebut dapat diaplikasikan sebagai media pembawa pupuk untuk tanaman dan sebagai pengondisi tanah. Superabsorben yang telah diperkaya oleh urea kemudian dilapisi dengan parafin 3, 6, dan 10%. Superabsorben tanpa pelapisan parafin melepaskan nitrogen sebesar 100% dalam waktu 240 menit, sedangkan superabsorben dengan pelapisan parafin 3% melepaskan nitrogen 100% dalam waktu 2 hari. Pelepasan nitrogen dalam waktu 2 hari dari superabsorben dengan parafin 6 dan 10% berturut-turut sebesar 68.40 dan 53.54%. Pelepasan nitrogen secara perlahan dengan cara pelapisan superabsorben dengan parafin dapat mengurangi besarnya nitrogen yang hilang dan dampak negatif terhadap lingkungan.
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Judul: Pengayaan Superabsorben Onggok-Poliakrilamida dengan Urea Melalui Metode Perendaman.
Abstrak: Superabsorbent can be synthesized from onggok and polyacrylamide using ammonium persulfate and N,N'-methylene bis-acrylamide through grafting-crosslinking methods. Superabsorbent can be enriched with urea fertilizer with slow nutrient-release properties. This superabsorbent enrichment can overcome the losses caused by conventional urea use because urea contains nitrogen nutrient which utilization efficiency is difficult to be increased. Enrichment of superabsorbent with urea was carried out by soaking superabsorbent in urea solution. Maximum enrichment was obtained in superabsorbent soaked in 1000 ppm urea solution for 17 and 24 hours with loading percentage of 36.72 and 32.48%. The release of nitrogen was tested in static aqueous media. Superabsorbent immersed in 1000 ppm urea solution for 17 hours released nitrogen most slowly, in 5 days. Release rate of nitrogen was 0.0370 ppm/min, and the nitrogen release pattern was in accordance with the pattern of plant nutrient uptake.
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Judul: Quantitative Trait Loci Mapping for Trait in Categorical Scale
Abstrak: Genes or regions on chromosome underlying a quantitative trait are called Quantitative Trait Loci (QTL). Characterizing genes controlling quantitative trait on their position in chromosome and their effect on trait is through a process called QTL mapping. In estimating the QTL position and its effect, QTL mapping basically utilize the association between QTL and DNA markers. However, many important traits are obtained in categorical scale, such as resistance from certain disease. From a theoretical point of view, QTL mapping method assuming continuous trait could not be applied to categorical trait. This research was focusing on the assessment of the performance of Maximum Likelihood (ML) and Regression (REG) approach employed in QTL mapping as well as the performance of Lander and Botstein (LB) and Piepho method in determining critical value in testing the existence of QTL for binary and ordinal trait by means of simulation study. The simulation study to evaluate the performance of ML and REG approach was conducted by taking into account several factors that may affecting the performance of both approaches. The factors are: (1) marker density; (2) QTL effect; (3) sample size; (4) shape of phenotypic distribution; (5) number of categories; and (6) number of QTL. Moreover, the simulation study for evaluating LB and Piepho method in determining critical value was conducted by generating distribution of the test statistic under null hypothesis. From simulation study, it was obtained that LB and Piepho method showing similar performance in determining critical value in testing the existence of QTL for binary and ordinal trait. The simulation study also indicating that both methods could be used in determining critical value in QTL mapping analysis for binary trait as well as for ordinal trait if the REG approach is used but not if ML approach is used due to their poor performance. In assessing the performance of ML and REG approach in QTL mapping analysis for binary trait, the two approaches showing comparable performance; whereas for ordinal trait REG approach showing poor performance compared with ML approach in estimating thresholds. As a result, in QTL mapping analysis, ML and REG approach could be used when dealing with binary trait, whereas ML approach is suggested when dealing with ordinal trait.
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