Judul: berjudul Respon Pertumbuhan Sorghum bicolor (L.) Moench pada Media Tanah Bekas Tambang Emas dengan Pemberian Humic Substance Complex.
Abstrak: Kegiatan revegetasi yang dilakukan di lahan pasca tambang umumnya terkendala kondisi tanah yang tidak subur untuk dilakukan penanaman sehingga menimbulkan permasalahan pertumbuhan vegetasi. Hal tersebut dikarenakan perubahan sifat fisik, kimia, dan biologi tanah akibat kegiatan eksplorasi, penataan lahan, eksploitasi dan pengaruh kegiatan ekstraksi seperti pembuangan limbah konsentrat. Salah satu cara dalam membenahi permasalahan tanah ialah dengan menggunakan HSC. Penelitian ini bertujuan untuk megukur respon pertumbuhan tanaman S. bicolor sebagai bioindikator pada tanah bekas tambang emas. Tanah yang digunakan merupakan tanah bekas kegiatan tambang emas di area Landfill PT Cibaliung Sumberdaya, Provinsi Banten. Konsentrasi larutan HSC yang digunakan yakni 1%, 2.5%, dan 5%. Parameter yang diamati meliputi panjang batang, jumlah akar primer, panjang akar primer, dan jumlah akar sekunder. Taraf konsentrasi larutan HSC 5% memberikan rataan hasil terbaik pada parameter panjang akar primer dengan 8.48 cm dan jumlah akar sekunder dengan 14 akar sekunder. Hal ini mengindikasikan pemberian larutan konsentrasi HSC dapat memperbaiki sistem perakaran pada tanah bekas tambang emas.
Keyword: HSC, S. bicolor, Tanah

Judul: Respon Sorghum bicolor (Linn.) terhadap Perbaikan Tanah Masam PT Holcim Tbk, Cibadak, Kabupaten Sukabumi
Abstrak: Mining activities have some obstacles such as acid soil where soil pH is low, high Al saturation, less of macro nutrients content, especially P, K, Ca, and Mg, and low organic content. The purpose of this research was to determine the right treatment of acid soil reparation in the post-mining land and see the impact of acid soils reparation in Sorghum bicolor plants. The research consisted of two factors, namely the treatment of medium acid soil (soil color is gray, reddish brown, brown) and the HSC (Humate Substance Complex) treatment in concentration 1L: 400L, 1L: 800L, and without HSC (control). The appropriate treatment for grey and brown acid soil reparation is adding HSC with a concentration of 1L: 800L, while reddish brown soil with a concentration of 1L:400L. The reparation acid soil with HSC has some impacts on the performance improvement such as increased root length, apical root length, quantity of lateral roots, and lateral root length and leaf color.
Keyword: toxicity, Sorghum bicolor, HSC, acid soil

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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