Judul: Effect of Waste Agar Saccharification Time Using H2SO4 on Reducing Sugar Produced
Abstrak: Gula pereduksi terbuat dari bahan berselulosa melalui proses hidrolisis. Limbah agar merupakan hasil samping yang dihasilkan dari produksi agar rumput laut. Limbah yang dihasilkan dapat mencapai 65-75%. Limbah agar memiliki kadar selulosa yang cukup tinggi yaitu 21,29%. Hidrolisis limbah agar dapat dilakukan secara kimia dan enzimatik. Hidrolisis secara kimia dapat dilakukan dengan menggunakan larutan asam sulfat (H2SO4), sedangkan hidrolisis secara enzimatik dapat dilakukan dengan menggunakan enzim selulase. Penelitian ini bertujuan menentukan pengaruh waktu hidrolisis asam limbah agar terhadap gula pereduksi yang dihasilkan dengan pembanding gula pereduksi hasil hidrolisis secara enzimatik. Lama waktu hidrolisis asam yang digunakan yaitu 15, 30, dan 45 menit. Kandungan total gula pereduksi terbaik terpadat pada perlakuan waktu hidrolisis asam selama 30 menit dengan nilai 34,92 mg/mL dan nilai glukosa 0,852 g/L, xylosa 9,55 g/L, dan xylitol 6,44 g/L. Hidrolisis secara enzim menghasilkan nilai gula pereduksi sebesar 104,09 mg/mL dan nilai glukosa 28,8 g/L. Perlakuan terbaik dalam penelitian ini yaitu hidrolisis asam selama 30 menit dan hidrolisis secara enzim yang menghasilkan nilai gula pereduksi dan glukosa yang lebih tinggi. Kata Kunci: gula pereduksi, hidrolisis asam, hidrolisis enzim, limbah agar, Sugar reduction is made of cellulose material through the process of hydrolysis. Waste agar is a byproduct resulting from the production of seaweed. The resulting waste can reach 65-75%. Waste to have high enough cellulose levels of 21,29%. Hydrolysis of waste so that it can be done chemically and enzymatically. Hydrolysis can be chemically done using a solution of sulfuric acid (H2SO4), while enzymatic hydrolysis can be done using cellulase enzymes. This study aims to determine the time influence of waste acid hydrolysis time on reducing sugars produced by comparing sugar reducing the results of enzymatic hydrolysis. The time of acid hydrolysis used is 15, 30, and 45 minutes. The total content of reducing sugar is the densest at 30 minutes of acid hydrolysis treatment with a value of 34,92 mg/mL with a glucose value of 0,852 g/L, xylose 9,55 g/L, and xylitol of 6,44 g/L. Enzyme hydrolysis produces a reduced sugar value of 104,09 mg/mL with a glucose value of 28,8 g/L. The best treatments in this study were acid hydrolysis for 30 minutes and enzyme hydrolysis which resulted in higher values of reducing sugars and glucose. Keywords: acid hydrolysis, agar waste, enzyme hydrolysis, sugar reduction
Keyword: acid hydrolysis, agar waste, enzyme hydrolysis, sugar reduction

Judul: Effect of Alkali Pretreatment on Enzymatic Hydrolysis in the Process of Making Bioethanol from Gracilaria sp.
Abstrak: Praperlakuan adalah proses perubahan dalam komposisi kimia, struktur makro, dan mikro dari lignoselulosa. Penelitian ini bertujuan untuk mengetahui pengaruh faktor praperlakuan dengan alkali NaOH 5% terhadap hidrolisis enzimatik pada proses pembuatan bioetanol menggunakan Gracilaria sp.sebagai bahan baku. Praperlakuan dengan alkali NaOH 5% dilakukan dengan variasi waktu yang berbeda yaitu 60, 90, dan 120 menit pada suhu 50oC. Setelah praperlakuan dilakukan proses hidrolisis enzimatis menggunakan enzim selulase pada shaker inkubator suhu 50oC, 150 rpm selama 72 jam, kemudian proses fermentasi selama 72 jam menggunakan kapang Saccaharomices cerevisiae. Hasil penelitian menunjukkan bahwa praperlakuan alkali NaOH 5% dapat meningkatkan kualitas biomassa Gracilaria sp. Kadar lignin yang dihasilkan sebesar 10,43 ± 0,15%. Hasil hidrolisis tertinggi dengan kandungan gula pereduksi sebesar 13,54 mg/ml. Uji kualitatif dengan K2Cr2O7 menunjukkan positif etanol pada larutan., Pretreatment is a process of changing the chemical composition, macrostructure, and microstructure of lignocellulose. This study aims to determine the effect of pretreatment factors with 5% NaOH alkali on enzymatic hydrolysis in the bioethanol production process using Gracilaria sp. as raw material. Pretreatment with 5% NaOH alkali was carried out with different time variations, namely 60, 90, and 120 minutes at a temperature of 50oC. After pretreatment, the enzymatic hydrolysis process was carried out using cellulose enzymes on a shaker incubator at a temperature of 50oC, 150 rpm for 72 hours, then the fermentation process for 72 hours using Saccharomices cerevisiae mold. The results showed that 5% NaOH alkali pretreatment could improve the quality of Gracilaria sp. biomass. The lignin content produced was 10.43 ± 0,15%. The highest hydrolysis resulted with a reduced sugar content of 13.54 mg/ml. Qualitative test with K2Cr2O7 showed positive ethanol in the solution.
Keyword: alkali pretreatment, enzymatic hydrolysis, Gracilaria sp., reducing sugar

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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