Judul: Optimization of Kraft Pulping Process of Rice Straw (Oryza sativa) as a Biomaterial for Biomedical Pulp Products
Abstrak: Jerami padi umumnya hanya dimanfaatkan sebagai pakan ternak, dibiarkan membusuk, dan dibakar cenderung memiliki dampak negatif terhadap lingkungan. Pemanfaatan jerami padi dapat menjadi alternatif sebagai bahan baku pulping karena mengandung selulosa cukup tinggi. Penelitian ini mengkaji potensi jerami padi sebagai bahan baku pulp untuk produk pulp biomedis menggunakan proses pulping kraft. Response surface methodology dengan model central composite design digunakan untuk mengoptimalkan kondisi pulping kraft jerami padi dengan kadar alkali aktif, sulfiditas dan waktu pemasakan sebagai variabel bebas. Pembuatan pulp dilakukan pada suhu 170 °C dengan nisbah L/W pemasakan 20:1 dan sampel 500 berat kering oven. Rendemen tersaring dan selektivitas delignifikasi digunakan sebagai parameter respon untuk menentukan kondisi pulping kraft yang optimum. Hasil penelitian menunjukkan bahwa kondisi pulping kraft optimum terdapat pada konsentrasi kadar alkali aktif 17%, sulfiditas 21,15%, dan waktu pemasakan 120 menit. Hal ini dapat ditunjukkan dengan rendemen pulp dan selektivitas delignifikasi yang tinggi. Pada kondisi optimum ini, pulp dapat digunakan sebagai bahan pembuatan pulp biomedis., Rice straw is generally only used as animal feed, left to rot, and burned tends to have a negative impact on the environment. The utilization of rice straw can be an alternative as raw material for pulping because it contains high enough cellulose. This study examined the potential of rice straw as a pulp raw material for biodegradable biomedical pulp products using the kraft pulping process. The response surface methodology with central composite design model was used for optimizing the kraft pulping condition of rice straw with active alkaline content, sulfidity and pulping time as independent variables. The pulping was conducted at a temperature of 170 °C with an L/W ratio of 20:1 and a sample of 500 ovens dry weight. Screen pulp yield and delignification selectivity were used as response parameters to determine the optimum pulping kraft condition. The result shows that the optimum pulping kraft conditions were found at a concentration of active alkaline content of 7%, sulfidity of 21,15%, and pulping time of 120 minutes. It can be indicated by high screen pulp yield and delignification of selectivity. In this condition, the optimum pulp can be used as a material for biomedical pulp.
Keyword: delignification of selectivity, pulp kraft, response surface methodology, screen yield

Judul: Manufacture and Characterization of Nonwood Paper from Dry Sugarcane Leaves and Rice Straw Waste as Paper Bags
Abstrak: Bahan nonkayu menjadi alternatif untuk mengatasi kebergantungan akan kayu dalam industri kertas. Daun kering tebu dan jerami padi merupakan dua contoh limbah pertanian pascapanen yang belum banyak dimanfaatkan. Penelitian ini bertujuan membuat kertas yang dapat digunakan sebagai kantong kertas dengan memanfaatkan limbah daun kering tebu dan jerami padi. Daun kering tebu dan jerami padi dicampurkan dalam tiga perlakuan (%b/b), T1 (50:50), T2 (75:25), dan T3 (25:75). Pulp dibuat secara kimiawi menggunakan NaOH 10% pada suhu ±100 °C selama 120 menit. Pulp lalu dicampurkan dengan perekat PVAc 5% sebelum dicetak menjadi lembaran berukuran A4. Hasil uji ANOVA menunjukkan pengaruh yang nyata (P<0,05) antara perbedaan nisbah bahan baku dengan nilai gramatur, ketahanan tarik, dan ketahanan sobek kertas. Perlakuan T3 menghasilkan kertas terbaik, memenuhi standar mutu kertas, dan dapat digunakan sebagai kantong kertas., Nonwood materials are an alternative to overcome dependence on wood in the paper industry. Dried leaves of sugarcane and rice straw are two examples of postharvest agricultural waste that has not been widely utilized. This research aims to prepare a paper that can be used as paper bags by utilizing dry leaf waste of sugarcane and rice straw. Dried leaves of sugarcane and rice straw were mixed in three treatments (%w/w), T1 (50:50), T2 (75:25), and T3 (25:75). The pulp was chemically prepared using 10% NaOH at ±100°C for 120 min. The pulp was mixed with 5% PVAc adhesive before molding into A4-sized sheets. The ANOVA test results showed a significant effect (P<0.05) between the various ratios of raw materials to grammage, tensile strength, and tear resistance of the paper. T3 treatment produced the best paper, complies with paper quality standards, and can be used as paper bags.
Keyword: agricultural waste, dry sugarcane leaves, paper, paper bags, rice straw

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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