Judul: Sintesis Kopolimer Onggok-Amino Akrilat Kationik Sebagai Pengendali Erosi Tanah
Abstrak: Onggok merupakan limbah pengolahan tepung singkong. Kandungan utama onggok adalah pati yang berupa polisakarida. Polisakarida merupakan polimer yang paling melimpah di alam. Kopolimerisasi onggok dengan polimer (2-dimetilaminoetil)metakrilat (DMAEMA) dapat menghasilkan kopolimer kationik karena DMAEMA memiliki gugus amina tersier yang dapat dikonversi menjadi ammonium kuaterner yang bersifat kationik. Penelitian ini bertujuan menyintesis kopolimer onggok-amino akrilat kationik dan mengetahui kemampuannya sebagai pengendali erosi tanah. Penelitian diawali dengan preparasi kopolimer onggok-amino akrilat melalui kopolimerisasi cangkok onggok-DMAEMA pada suhu 70 °C selama 3 jam. Selanjutnya dilakukan metilasi pada kopolimer onggok-amino akrilat menggunakan dimetilsulfat (DMS) pada suhu 65 °C sehingga diperoleh kopolimer onggok-amino akrilat kationik yang kemudian diuji kemampuannya sebagai pengendali erosi tanah pada tanah lempung liat berpasir dan lempung liat berdebu pada intensitas air hujan 45 mm jam-1 dan 100 mm jam-1. Kopolimer onggok-amino akrilat dapat disintesis melalui metode kimia dengan kopolimerisasi pencangkokan-penautan silang pada onggok dan monomer DMAEMA, penaut silang metilena bis-akrilamida dan inisiator ammonium persulfat sehingga diperoleh rendemen 44.66% dan nisbah pencangkokan 42.15%. Kopolimer ongok-amino akrilat kationik berhasil disintesis melalui metilasi terhadap kopolimer onggok-amino akrilat dengan menggunakan agen metilasi dimetilsulfat di dalam pelarut dimetilformamida dengan konversi 94.96% pada waktu sintesis 18 jam dan nisbah kopolimer onggok-amino akrilat:DMS sebesar 1:2 (b/v). Kopolimer onggok-amino akrilat kationik efektif untuk mengurangi erosi pada tanah lempung liat berdebu dan lempung liat berpasir dengan intensitas air hujan 45 mm jam-1 dan 100 mm jam-1. Kopolimer onggok-amino akrilat kationik efektif untuk menurunkan volume limpasan total dan laju limpasan akhir pada tanah lempung liat berpasir dengan intensitas air hujan 45 mm jam-1 hingga 65.26%, meningkatkan volume infiltrasi total dan laju infiltrasi akhir pada tanah lempung liat berdebu dengan intensitas air hujan 45 mm jam-1 hingga 192.80%, menurunkan kedalaman limpasan pada tanah lempung liat berpasir dengan intensitas air hujan 45 mm jam-1 hingga 65.25%, menurunkan TDS pada tanah lempung liat berpasir dengan intensitas air hujan 45 mm jam-1 hingga 48.36%, menurunkan TSS dan bobot tanah tererosi total pada tanah lempung liat berdebu dengan intensitas air hujan 45 mm jam-1 hingga 93.16% dan 82.05%.
Keyword: onggok, DMAEMA, erosi tanah

Judul: Sintesis dan Pencirian Superabsorben Onggok-g-Asam Akrilat
Abstrak: Onggok is a solid waste from tapioca processing. The aim of this study is to modify onggok into superabsorbent polymer. The modification was conducted through grafting and crosslinking of acrylic acid (AA) on onggok backbone, with N,N’-methylene-bis-acrylamide (MBA) as crosslinker, and ammonium persulfate (APS) as initiator. The synthesis was conducted at 70 oC for 3 hours and the water absorption capacity of the copolymer products were then measured. A 761.01 g/g value was obtained from copolymer composed of 4.5 g onggok, 25.5 g AA, 24 mg MBA, and 24 mg APS. The occurence of grafting-crosslinking copolymer was confirmed by infrared spectra, which exhibited all characteristic bands of both polysaccharide fractions of onggok and AA units. The absorbency of superabsorbents were measured in solutions having pH ranging from 2 to 11. The maximum value was 630.65 g/g at pH 6.65. The superabsorbent’s absorbency in salt solution was decreased with increasing ionic strength up to 0.342 M concentration of NaCl. The absorbency kinetics of superabsorbents were studied as well and the rate parameter in water was found to be 2.61 minutes for onngok with 60 mesh particle size.
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Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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