Judul: Perbaikan Parameter Kuat Geser Clay Shale menggunakan Xanthan Gum Modifikasi Polyvinyl Alcohol (PVA)
Abstrak: Tanah mendukung keberlanjutan konstruksi, namun tanah ekspansif seperti Clay Shale menimbulkan tantangan. Penggunaan semen sebagai bahan stabilisasi kimiawi berdampak lingkungan. Biopolimer seperti Xanthan Gum dapat mengurangi dampak negatif, meskipun memiliki kelemahan. Penambahan bahan aditif seperti Polyvinyl Alcohol (PVA) diperlukan untuk mengatasi kekurangan tersebut. Pada penelitian ini, pengaruh penambahan Xanthan Gum dan PVA serta kombinasinya terhadap parameter tanah dievaluasi. Parameter tanah yang dievaluasi adalah properti tanah berupa indeks plastisitas, kadar air dan kuat geser tanah. Pencampuran Xanthan Gum dimodifikasi PVA terhadap Clay Shale menggunakan metode kombinasi wet mixing dan dry mixing. Hasil penelitian ini menunjukkan bahwa penambahan Xanthan Gum, PVA dan modifikasinya mampu meningkatkan nilai indeks plastisitas tanah berturut-turut sebesar 156%, 98% dan 6%. Nilai indeks plastisitas pada sampel untreated maupun treated menunjukkan peningkatan. Modifikasi Xanthan Gum menggunakan Polyvinyl Alcohol mampu meningkatkan nilai kohesi dan sudut gesek dalam pada Clay Shale sebesar 200% dan 103%. Penelitian ini menyimpulkan bahwa penambahan PVA pada Xanthan Gum mampu meningkatkan kekuatan Clay Shale secara efektif
Keyword: Clay Shale, Cohesion, Friction angle, Polyvinyl Alcohol, Xanthan Gum

Judul: Improvement of Shear Strength Parameters of Clay Shale by Adding Calcite using SCU-CP Method
Abstrak: Clay shale menyebabkan masalah dalam konstruksi apabila telah tersingkap karena sifat ekspansif dan mudah lapuk. Metode perbaikan tanah dengan calcite precipitation efektif meningkatkan daya dukung dan menurunkan potensi pengembangan tanah ekspansif. Penelitian ini bertujuan mengevaluasi peningkatan parameter kuat geser clay shale dengan metode calcite precipitation. Penelitian ini dilakukan dengan uji properties tanah, laju hidrolisis dan rasio presipitasi, serta uji direct shear pada tanah jenuh (saturated) dan kering (dry). Properties clay shale menunjukkan nilai PL, LL, dan PI sebesar 41.60%, 21.97%, dan 19.62%, dengan klasifikasi tanah lempung plastisitas rendah hingga sedang (CL). Konsentrasi optimum untuk treatment diperoleh pada konsentrasi kedelai 20 g/L dengan rasio presipitasi 93%, Pada sampel treated-saturated peningkatan nilai kohesi (c') dari 4.10 kPa menjadi 12.07 kPa dan sudut gesek internal (φ') dari 0.54° menjadi 2.87°. Peningkatan signifikan pada sampel treated-dry dengan c' dari 7.53 kPa menjadi 183.84 kPa dan φ' dari 2.31° menjadi 19.25°. Penerapan metode SCU-CP lebih efektif pada clay shale., Clay shale, known for its expansive and weathered characteristics, poses challenges in construction when exposed. The calcite precipitation method offers a viable solution to bolster load-bearing capacity and counteract potential soil expansion while ensuring reversible changes. This study aims to evaluate improvements in the shear strength parameters of clay shale through the calcite precipitation method. The research involved soil properties tests, hydrolysis rate and precipitation ratio analyses, and direct shear tests on both saturated and dry soil specimens. Results showed clay shale samples with PL, LL, and PI values of 41.60%, 21.97%, and 19.62%, respectively, categorizing them as low to medium plasticity clayey soils (CL). The optimal treatment concentration was determined at 20 g/L soybean concentration with a precipitation ratio of 93%. In treated-saturated conditions, cohesion (c') increased from 4.10 kPa to 12.07 kPa, and internal friction angle (φ') rose from 0.54° to 2.87°. Remarkable enhancements were observed in treated-dry samples, with c' increasing from 7.53 kPa to 183.84 kPa, and φ' rising from 2.31° to 19.25°. The SCU-CP method effectively improved the properties of dry clay shale.
Keyword: Calcite, clay shale, expansive, residual shear strength, SCU-CP

Judul: Mitochondrial DNA Gene Organization and Phylogenetic Relationship of Naja siamensis
Abstrak: Naja siamensis is one of Asiatic cobra in the Family of Elapidae, known as a cryptic snake. It has many morphological variations that lead to misidentification. Misidentification can cause the wrong concept in developing antivenom types due to high snakebite cases occur in Thailand. Thus, an accurate species identification using a molecular approach is crucially required. Mitochondrial DNA has been used widely in snake molecular studies. These studies were aimed to determine the arrangement of the N. siamensis partial mitochondrial genes using reptile-oriented primers and to reveal the phylogenetic relationship among other species of Asian cobra. DNA extraction was carried out based on the standard DNA salting-out protocol and was conducted by bioinformatics analysis using BLASTn and MEGA 6 software. Gene annotation was performed against N. kaouthia complete genome. A total of 3121 bp of N. siamensis mtDNA genes were sequenced consisting of partial of six regions: 16S rRNA, ND1, tRNA-Ile, CRII region, tRNA-Leu, tRNA-Gln, and COI genes. The mtDNA gene organization of N. siamensis was predicted to has a similar pattern with the common Elapidae mtDNA gene organization. This study showed that there is a monophyletic form in Naja genus and N. kaouthia is the closest species with N. siamensis based on partial 16S rRNA and ND1 gene.
Keyword: 16S rRNA, Elapidae, ND1, phylogenetic relationship