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: Penggunaan Selulosa TandanKosong Kelapa Sawit dan Selulosa Mikrobial dari Nata de Cassavasebagai Pensubstitusi Selulosa Kayu dalam Pembuatan Kertas
Abstrak: Nowadays, forest-extracted wood cellulose still predominantly serves as raw material for pulp and paper manufacture in Indonesia. Consequently, the deforestation rate has alarmingly increased 2% per year. Attempts are necessary to seek alternative cellulose sources that sound potentially available, among which are empty oil-palm fruit bunches (EOPFB) and microbial-cellulose, as synthesizedwith the aid of microorganisms from substrate containing glucose, fructose, sucrose, or other simple carbohydrates, such as juicy waste from tapioca processing (e.g. nata de cassava). In this research, pulp of nata de cassava‟s microbial cellulose was mixed with EOPFB pulp at various proportions (w/w), i.e. 100%+0%, 75%+25%, 50%+50%, 25%+75%, 0%+100%to be processed into pulp and paper. Grammage target made was 60 gr/m2 and 120 gr/m2. Prior to paper-sheet forming, additives were added to such mixture (i.e. 2% alum, 2.5% tapioca starch, and 5% kaolin). Sheet forming also made without additives (as control). The forming of each combination between mixture proportion, grammage target and additive/control-use was replicated 2 times, and the data examined comprised pulp/paper physical and strength properties. The data were analyzed using a completely randomized design with factorial pattern. The yields of microbial-cellulose pulp and of EOPFB pulp were consecutively (wet basis) 60,09% and 61,619%. Physical and strength properties of paper with grammage 60 gr/m2and 120gr/m2consecutively, i.e. water content (4,04-8,95% & 3,83- 9,01%), grammage (59,8-78,92gr/m2& 107,64-145,32 gr/m2), tensile index 0,0056-0,0424 & 0,01002-0.06499 kNm/g), tear index (4,04-8,22 & 4,55-7,72 mN m2/gr),folding endurance (3,5-108,5 & 4-397,5), Cobb60 (56,86-211,32 & 75,03- 398,12 g/m2 for the smooth surface; and 51,07-218,91 & 57,65-404,46 g/m2for the rough/lower surface), brightness (15,64-38,03% & 13,1-26,26%) and printing opacity (62,81-97,55% & 42,99-99,38%). Analysis on biomass conversion revealed that the manufacture of paper from the mixture (w/w) of nata de cassava‟s microbial cellulose (50%) and empty oil palm fruit bunch pulp (50%) through the expansion of each cultivating areas, both totaling 200 ha can substitute for 4.247.156forest-tree stands per year. With this tree-saving figure, it can afford the CO2absorption (uptake) from the air equal to approximately 594.601,85 tons of CO2 per year.
Keyword: carbon uptake, biomass conversion analysis, pulp/paper, empty oil-palm fruit bunch, nata de cassava, microbial cellulose

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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