Judul: Characterization of Antibacterial Properties in Peptide  Filtrate from Commercial Dadih Collected at Varied bamboo
Abstrak: Dadih adalah produk fermentasi susu tradisional yang berasal dari Sumatera Barat, dibuat dari susu kerbau melalui fermentasi alami dalam bambu. Dadih ber potensi menghasilkan peptida bioaktif, salah satunya peptida antibakteri. Penelitian ini bertujuan untuk karakterisasi sifat antibakteri dari filtrat peptida yang didapat dari dadih komersial dengan ukuran bambu berbeda. Metode yang dilakukan yaitu, filtrasi peptida dengan cutoff 3 kDa, pengukuran pH, total asam teritrasi, kadar protein (Lowry), dan pengujian antibakteri dengan Staphylococcus aureus, Bacillus cereus, Escherichia coli, dan Salmonella typii. Hasil penelitian menunjukkan ukuran bambu berbeda tidak memiliki pengaruh yata (P>0,05) terhadap kadar protein, pH, dan total asam pada dadih. Ukuran bambu berbeda tidak berpengaruh nyata (P>0,05) terhadap daya hambat antibakteri dadih pada bakteri Gram positif. Namun, memiliki pengaruh nyata (P<0,05) terhadap daya hambat antibakteri dadih pada bakteri Gram negatif yaitu E. coli dan S. typii. Hal ini menunjukkan aktivitas antibakteri dadih lebih berpengaruh terhadap bakteri Gram negatif karena produksi senyawa-senyawa antibakteri yang berbeda pada setiap bambu.
Keyword: dadih, antibakteri, bambu, filtrat peptida

Judul: Physical Properties and Protein Profiling of Commercial Traditional Dadih Produced from Different Bamboos.
Abstrak: Susu kerbau digunakan sebagai bahan baku dan difermentasi secara tradisional dalam bambu. Penelitian ini meneliti karakteristik fisik dan profil protein dadih komersial yang diproduksi dengan bambu berukuran berbeda di Sumatera Barat. Data yang diamati meliputi pH, viskositas, kadar protein, dan SDSPAGE, yang dianalisis dengan One-Way ANOVA. Hasil penelitian menunjukkan bahwa pH dan viskositas dadih tidak berbeda signifikan (P>0,05) antara bambu kecil dan bambu besar. Namun, kadar protein menunjukkan perbedaan signifikan (P<0,05). Profil protein dadih dari tabung besar menunjukkan berat molekul antara 8,14 kDa - 22,30 kDa, sedangkan dari tabung kecil berkisar antara 9,29 kDa - 57,22 kDa. SDS-PAGE mengungkapkan lima pita protein dalam dadih tabung kecil, termasuk BSA, a-kasein, ß-laktoglobulin, dan a-laktalbumin, dengan satu pita tidak teridentifikasi. BSA dan ß-laktoglobulin tidak ditemukan dalam dadih tabung besar, menunjukkan laju proteolitik yang lebih ekstrim dalam tabung besar dibandingkan tabung kecil., Buffalo milk is used as the raw material and is traditionally fermented in bamboo. This study examines the physical characteristics and protein profiles of commercial dadih produced using different sizes of bamboo in West Sumatra. The observed data include pH, viscosity, protein content, and SDS-PAGE, analyzed using One-Way ANOVA. The results of the study show that the pH and viscosity of the dadih did not differ significantly (P>0.05) between small and large bamboo. However, the protein content showed a significant difference (P<0.05). The protein profile of dadih from large bamboo tubes showed molecular weights ranging from 8.14 kDa to 22.30 kDa, while in small bamboo tubes, the molecular weights ranged from 9.29 kDa to 57.22 kDa. SDS-PAGE revealed five protein bands in dadih from small bamboo tubes, including BSA, a-casein, ß-lactoglobulin, and a-lactalbumin, with one band unidentified. BSA and ß-lactoglobulin were not found in dadih from large bamboo tubes, indicating a more extreme proteolytic rate in large tubes compared to small tubes.
Keyword: olahan susu, dadih, protein

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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