Judul: In Silico Study: The Potential of Kaffir lime leaves  (Citrus hystrix) as an Alternative to Antibiotic Growth Promoter (AGP) in Broiler  Chickens
Abstrak: Ayam broiler merupakan ternak yang rentan terinfeksi mikroorganisme pa togen, sehingga banyak peternak menggunakan Antibiotic Growth Promoter (AGP). AGP merupakan imbuhan pakan yang diberikan untuk memacu pertum buhan dan memperbaiki saluran pencernaan, namun kini sudah dilarang penggunaannya. Pelarangan AGP menyebabkan peralihan penggunaan imbuhan pakan seperti imbuhan pakan fitogenik. Daun jeruk purut (Citrus hystrix) mem iliki senyawa aktif metabolit sekunder sehingga berpotensi untuk dijadikan im buhan pakan fitogenik. Penelitian ini bertujuan menganalisis potensi senyawa ak tif daun jeruk purut dengan melihat berbagai aktivitas biologi dan kemampuan dalam menghambat bakteri E. coli dan S. aureus menggunakan metode in silico. In silico merupakan metode komputasi yang digunakan untuk memprediksi kiner ja senyawa aktif suatu bahan. Senyawa aktif yang diperoleh berasal dari jurnal terindeks scopus, kemudian dilakukan pencarian kode SMILES, nilai probable activity (Pa), dan prediksi interaksi antara senyawa aktif dengan protein bakteri E.coli dan S.aureus. Hasil yang didapatkan yaitu 143 senyawa aktif memiliki kode SMILES dan 96 dari 143 senyawa aktif memiliki nilai Pa 0,300 pada ak tivitas antibakteri, antioksidan, penghambat glikosiltransferase peptidoglikan, antiinfeksi, imunomodulator, dan antiinflamasi sehingga berpotensi sebagai alter natif AGP. Daun jeruk purut juga mampu menghambat bakteri E. coli dan S. aureus secara in silico., Broiler chickens are livestock that are susceptible to infection with pathogenic microorganisms, so many farmers use Antibiotic Growth Promoter (AGP). AGP is a feed additive given to stimulate growth and improve the digestive tract, but its use is now prohibited. The prohibition of AGP has led to a shift in the use of feed additives such as phytogenic feed additives. Kaffir lime leaves (Citrus hystrix) have active secondary metabolite compounds that have the potential to be used as phytogenic feed additives. This study aims to analyzing the potential of the active compounds and the activity kaffir lime leaves by looking at various biological activities and abilited E. coli and S. aureus bacteria using the in silico method. In silico is a computational method used to predict the performance of the active compound of a material. The active compounds were obtained from scopus indexed journals, then searched for the SMILES code, probable activity (Pa) values, and predicted interactions between the active compounds and the proteins of E.coli and S.aureus bacteria. The results obtained were 143 active compounds had SMILES code and 96 of 143 active compounds had a Pa 0,300 value for antibacterial, antioxidant, peptidoglycan glycosyltransferase inhibitor, anti-infective, immunomodulatory, and anti-inflammatory so that it has the potential to be used as an alternative to AGP. Kaffir lime leaves are also able to inhibit E. coli and S. aureus bacteria in silico.
Keyword: antibiotik growth promoter, in silico

Judul: Potensi Daun Sambung Nyawa (Gynura procumbens (Lour.) Merr.) sebagai Alternatif Antibiotic Growth Promoter pada Ayam Broiler”
Abstrak: Antibiotic Growth Promoter (AGP) merupakan antibiotik yang sudah dilarang penggunaanya pada ayam broiler. Senyawa fitokimia tumbuhan atau fitogenik dapat ditambahkan pada pakan sebagai alternatif AGP, salah satunya adalah daun sambung nyawa. Penelitian ini bertujuan menganalisis aktivitas dan menguji kemampuan senyawa aktif daun sambung nyawa (Gynura procumbens (Lourr.) Merr.) terhadap penghambatan bakteri E. coli dan C. perfringens melalui simulasi secara komputasi untuk memprediksi potensinya sebagai alternatif pengganti AGP pada ayam broiler. Analisis metode in silico yang digunakan yaitu PASS dan STITCH. Analisis PASS menunjukkan nilai Pa lebih dari 0,3 dinyatakan berpotensi. Daun sambung nyawa berpotensi sebagai alternatif AGP melalui aktivitas antibakteri, penghambatan peptidoglikan glikosiltransferase, antiinfeksi, antiinflamasi, dan antioksidan. Senyawa quercetin dan apigenin daun sambung nyawa mempunyai potensi untuk menghambat pertumbuhan bakteri E. coli dan C. perfringens melalui penghambatan biosintesis asam lemak dan pembentukan dinding sel bakteri., Antibiotic Growth Promoter (AGP) is an antibiotic that has been banned for use in broiler chicken. One of phytochemical compound as an alternative AGP substitute is Gynura procumbens leaves. The aims of this research was to analyze the activity and to evaluate the active compound of Gynura procumbens (Lour.) Merr. leaves against the inhibition of E. Coli and C. Perfringens through computational simulation to predict its potential as an alternative to AGP in broiler chickens.The method used is PASS and STITCH analysis. PASS analysis shows a Pa value of more than 0.3 as a potential source. Gynura procumbens (Lour.) Merr. leaves had potential as an alternative AGP through its antibacterial activity, inhibition of peptidoglycan glycosyltransferase, anti-infection, anti-inflammatory, and antioxidant activity. Quercetin and apigenin compounds in Gynura procumbens (Lour.) Merr. leaves had a potency to inhibit the growth of E. Coli bacteria and C. perfringens through fatty acid biosynthesis and formation of bacterial cell walls inhibition.
Keyword: AGP, C. perfringens, E. coli, Gynura procumbens leaves, in silico

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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