Judul: Elektrode Komposit Zeolit sebagai Biosensor Berbasis Tirosinase
Abstrak: Tyrosinase is a copper-containing oxidase, which catalyzes the first 2 steps in mammalian melanogenesis and responsible for enzymatic browning reactions. This study aims to develop and characterize tyrosinase biosensor of zeolite composite and its stability. The enzyme should be properly attached to the transducer for maintaining enzyme activity. Tyrosinase activity was monitored by L-DOPA as a substrate. The optimum conditions of tyrosinase activity obtained by respon optimizer were tyrosinase 50 U/mL and zeolite 150 mg/mL. Using of ferrocene as mediator and zeolite as the immobilization matrix on electrode increased the activity of tyrosinase. KMapp and Imaks app values of tyrosinase were determined by Lineweaver-Burk method, giving 6.04 mM and 6.42 mM, respectively. The electrode of zeolite as immobilizing matrix was relatively stable until 2 hours, the remaining tyrosinase activity was 87.45%
Keyword: tyrosinase inhibitor, tyrosinase-based electrode, biosensor

Judul: Glucose biosensor using a glucose dehydrogenase flavin adenine dinucleotide electrochemically immobilized on zeolite nanoparticles
Abstrak: A glucose biosensor was developed to measure blood glucose levels. The performance of these new glucose biosensors was continuously improved, producing better performance and stability. The technique selection and immobilization matrix are key factors for biosensor development, so that the prospecting of materials that can be used as a matrix for supporting enzyme, continue to be explore. The purpose of this study was to determine the activity and stability of the enzyme glucose dehydrogenase (GDH) that were immobilized on zeolite nanoparticles (NPZ) and determine the kinetic parameters and analytical performance by electrochemical methods. The resulting enzyme electrode with NPZ and enzyme electrode with zeolite A showed a high activity against the enzyme electrode glucose than without NPZ. The reaction kinetics of third electrodes of enzyme followed the Dixon equation. The 𝐼����𝑚����𝑎����𝑥����𝑎����𝑝����𝑝���� values for enzyme electrode without NPZ, with NPZ, and with zeolite A were 27.25 μA, 77.52 μA, and 48.54 μA, respectively. The 𝐾����𝑀����𝑎����𝑝����𝑝���� values for GDH enzyme that immobilized on the NPZ were 1.16 mM, 12.30 mM for GDH enzyme that immobilized on zeolite A and 0.95 mM for GDH enzyme immobilization without NPZ. The enzyme electrode without NPZ, with NPZ, and with zeolite A also showed a high sensitivity with value for the sensitivity were 0.58 μA mM-1, 0.81 μA mM-1, and 2.51 μA mM-1, respectively. The third enzyme electrodes showed different linear area with range for the enzyme electrode without NPZ, with NPZ and with zeolite A were 1.00-15.00 mM, 2.00-20.00 mM, and 0.06-10.00 mM, respectively. The blood glucose level of normal person ranged from 4 to 6 mM, so that the enzyme electrode with NPZ and without NPZ are suitable for use in the determination of the concentration of blood glucose. While the enzyme electrode with zeolite A has a smaller range so it is more suitable to use in the determination of glucose concentration in the foods or beverages. The enzyme electrode with NPZ and the enzyme electrode with zeolite A showed a good accuracy with relative error values were 3.84% and3.48%, respectively. Repeatability measurements also showed a good precission results with relative standard deviation values (%RSD) for the enzyme electrode with NPZ and enzyme electrode with zeolite A were 3.83% and 3.16%, respectively. By combining two immobilization techniques, physical adsorption on zeolite and entrapment on carbon paste, high enzymatic activity, good accuracy, and repeatability was attained. The enzyme electrode with NPZ and the enzyme electrode with zeolite A demonstrated a good electrochemical response toward glucose, allowing it to detect blood glucose levels and glucose levels in foods and beverages.
Keyword: glucose biosensor, immobilization, zeolite

Judul: Kajian Numerik Peluncuran Kapal Jaring Cumi DI Galangan Kapal Marunda Dan Muara Angke, Jakarta Utara
Abstrak: Peluncuran kapal merupakan salah satu proses dalam pembangunan kapal. Ketika proses peluncuran kapd terjadi perpindahan berat kapal dari landasan pernbangunan ke laut. Kapal yang diluncurkan di galangan kapal Marunda lebih sering mengaIami kerusakan dibandingkan kapal yang diluncurkan di Galangan kapal Muara Angke. Bagian kapal yang sering rusak pada saat peluncuran adalah bagian lambung kapal dan bagian papan dasar dekat gading-gading kapal. Hal ini terjadi karena para pengrajin kapal di kedua galangan kapal tersebut meluncurkan kapal yang dibangunnya berdasarkan pengalaman. Permasalahan yang ingin dipecahkan dalam skripsi ini adalah bagairnana para desainer dan pengrajin dapat memperkirakan seberapa besar gaya-gaya yang bekerja pada sebuah kapal ketika sedang diluncuikan. Komputasi gaya-gaya ini sangat penting untuk diketahui sebelum kapal diluncurkan dan kondisi masuknya kapal ke dalam laut dapat berlangsung dengan mulus.
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