Judul: The exploration of chlorophyll and vitamin C content in weeds as a raw materials of food supplements
Abstrak: Gulma sebagai tumbuhan belum banyak diketahui manfaatnya. Gulma yang tumbuh di sekitar lahan pertanian mengakibatkan penurunan laju pertumbuhan dari tanaman yang dibudidayakan. Salah satu cara untuk memanfaatkan gulma adalah dengan menjadikan tumbuhan gulma sebagai sumber klorofil dan vitamin C yang dapat digunakan sebagai bahan dasar suplemen makanan. Sampel tumbuhan gulma diambil di daerah sekitar kampus IPB Darmaga dengan metode acak sederhana. Gulma yang diekstrak kandungan klorofil dan vitamin C-nya terdiri dari enam spesies gulma yaitu Ageratum conyzoides, Bidens pilosa, Paspalum conjugatum, Eleusine indica, Axonupus compressus, dan Rottboelia exaltata. Rottboelia exaltata mempunyai kandungan klorofil total paling tinggi (7.77 mg/L) diikuti Eleusine indica (6.94 mg/L), Ageratum conyzoides (5.18 mg/L), Axonupus compressus (4.61 mg/L), dan Paspalum conjugatum (3.00 mg/L). Gulma yang memiliki kandungan klorofil paling rendah yaitu Bidens pilosa (2.69 mg/L). Kandungan vitamin C pada keenam sampel gulma yang diuji berkisar antara 0.47-0.91 mg/100 g. Kandungan klorofil pada Rottboelia exaltata, Eleusine indica dan Ageratum conyzoides berpotensi sebagai bahan suplemen makanan dan kandungan vitamin C pada tumbuhan gulma yang diuji tidak berpotensi sebagai bahan dasar suplemen makanan., The benefit of weeds still rarely known. Weeds in agricultural area could decreased the rate of plants cultivation growth. The advantage of weeds is to be source of chlorophyll and vitamin C. Weed samples were collected from the IPB, Darmaga campus area with simply random method. Weeds were extracted for chlorophyll and vitamin C. The sample consisted of six weed species that were Ageratum conyzoides, Bidens pilosa, Paspalum conjugatum, Eleusine indica, Axonupus compressus, and Rottboelia exaltata. Rottboelia exaltata has the highest total chlorophyll content (7.77 mg/L) followed by Eleusine indica (6.94 mg/L), Ageratum conyzoides (5.18 mg/L), Axonupus compressus (4.61 mg/L), and Paspalum conjugatum (3.00 mg/L). The lowest chlorophyll content of weed samples is in Bidens pilosa (2.69 mg/L). The vitamin C content of the six weeds were 0.47-0.91 mg/100g. The Chlorophyll content in Rottboelia exaltata, Eleusine indica and Ageratum conyzoides are potential for a food supplement but vitamin C content are not potential for a raw material of dietary supplements. Keywords: Weeds, Chlorophyll, Vitamin C
Keyword: Gulma, Klorofil, Vitamin C

Judul: Dominance of Weed Upon Several Character of The Palm Environment and Its Potential Resistance to Herbicide glyphosate
Abstrak: Pengendalian gulma secara kimiawi pada lahan sawit secara berulang dalam jangka waktu yang lama dapat menyebabkan terjadinya potensi resistensi pada gulma. Tujuan penelitian adalah mengetahui gulma dominan pada karakter lingkungan yang berbeda dan mengetahui potensi resistensi terhadap herbisida glifosat. Benih gulma diambil dari Perkebunan Kelapa Sawit Jonggol IPB-Cargill Singasari, Kecamatan Jonggol, Bogor, Jawa Barat. Penelitian dilaksanakan pada bulan Januari sampai September 2020. Metode yang dilakukan dalam penelitian ini ada dua, yaitu identifikasi gulma dominan dan pengujian resistensi. Gulma dominan diidentifikasi dengan cara melakukan analisis vegetasi pada tiga blok terpilih dan dihitung berdasarkan nilai NJD. Gulma dominan yang didapat yaitu Eleusine indica. Pengujian resistensi dilakukan dengan melakukan penanaman dan pengaplikasian herbisida glifosat pada gulma dominan (E.indica) untuk menentukan tingkat resistensi herbisida glifosat. Nisbah resistensi dihitung dari nilai perbandingan Lethal Dose50 gulma resisten dengan gulma sensitif. Hasil penelitian menunjukkan bahwa keragaman gulma pada blok 1, 2, dan 5 didominasi oleh famili Poaceae. Jenis gulma yang mendominasi pada lahan curam (22.00%) dan intensitas cahaya rendah (1,135.20 x 1000 lux) yaitu spesies Ottochloa nodosa dan jenis gulma yang mendominasi pada lahan landai (14.86%) hingga datar (8.00%) dan intensitas cahaya sedang (1,427.60 x 1000 lux) hingga tinggi (1,979.00 x 1000 lux) yaitu gulma spesies E. indica. Perbedaan gulma dominan ini di pengaruhi oleh intensitas cahaya dan kemiringan (topografi) lahan. Perbedaan karakteristik tersebut menunjukkan adanya potensi resistensi gulma E. indica pada Blok 5 yang ditunjukkan dengan nilai Lethal Time50 sebesar 1.53 hari, Lethal Dose50 sebesar 5.35, dan nilai N, Weeds chemical control on palm oil estate over a long period of time can lead to weeds resistance. The purpose of the study was to reveal the dominant weeds in some environmental characters and to know the potential resistance to glyphosate herbicides. Weed seeds were taken from Jonggol Oil Palm Plantation IPB-Cargill Singasari, Jonggol Subdistrict, Bogor, West Java. The research was carried-out from January to September 2020. The research began with vegetation analysis to identify the dominant weeds in each selected block. Weeds was identied and calculated. Dominant weeds was defined by the highest Summed Dominance Ratio (SDR) Then the dominant weed was chosen to be tested for its resistance to glyphosate herbicides. The dominant weed seed, namely Eleusine indica, were planted in plastic pots 15 cm x 9 cm size containing as much as 20 seeds in each pot. At the age of 14 days after planting or after the appearance of 3 leaves various glyphosate herbicides dose was applied. Weeds dominant on the slope of ramps (14.86%), i.e Block 2, up to flat (8.00%) i.e Block 5, and medium light intensity (1,427.60 x 1000 lux) to high (1,979.00 x 1000 lux) was Eleusine indica, while the dominant weed on a steep slope (22.00%) 1.e. Block 1, and low light intensity (1,135.20 x 1000 lux) was Ottochloa nodosa species. Those different in characteristics also revealed the potential of Eleusine indica resistance. Proved in Block 5 shown by LT50 values of 1.53, LD50 of 5.35, and NR values in the range of 2 – 6 indicating the occurrence of low resistance.
Keyword: Dosis, Eleusine indica, Kimiawi, Pengendalian, Vegetasi

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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