Judul: Functionalization of Agar Processing Waste-Derived Nanocellulose with Silver Nanoparticles for Antibacterial Hydrogel Production
Abstrak: Limbah padat pengolahan agar ditransformasi menjadi nanoselulosa untuk diaplikasikan dalam berbagai bidang. Penelitian bertujuan mendapatkan nanofibril selulosa dari limbah padat pengolahan agar-agar, menentukan pengaruh fikosianin sebagai reducting agent dalam fungsionalisasi nanoselulosa dengan nanopartikel perak (CNF/AgNPs), menentukan aktivitas antibakteri dari hidrogel alginat yang diimobilisasi CNF/AgNPs. Nanofibril selulosa (CNF) telah berhasil diperoleh dengan perlakuan Hydated Deep Eutectic Solvent (choline chloride:oxalic acid) dengan diameter fiber dan nilai kristalinitas masing-masing sebesar 80,37±1,06 nm dan 85,66%. Nanofibril selulosa berhasil difungsionalisasikan dengan nanopartikel perak (AgNPs) menggunakan fikosianin sebagai reducting agent. Gugus fungsi aldehida (C=O) pada bilangan gelombang 1729 cm-1 dalam nanofibril selulosa berhasil berikatan dengan AgNPs. Hidrogel alginat yang diimobilisasi perlakuan CNF/AgNPs 20% memiliki aktivitas antibakteri tertinggi pada bakteri Gram negatif Pseudomonas aeruginosa, namun aktivitas antibakteri terhadap bakteri Gram positif Propionibacterium acne dan Staphylococcus aureus tidak berbeda nyata dengan perlakuan lainnya. Imobilisasi CNF/AgNPs pada hydrogel alginate memiliki potensi untuk diaplikasikan sebagai antibacterial wound dressing., Solid agar processing waste is transformed into nanocellulose for various applications. The research aim to obtain cellulose nanofibrils from solid agar processing waste, determine the influence of phycocyanin as a reducting agent in the functionalization of nanocellulose with silver nanoparticles (CNF/AgNPs), and assess the antibacterial activity of alginate hydrogel immobilized with CNF/AgNPs. Cellulose Nanofibrils (CNF) were successfully obtained through treatment with a Hydrated Deep Eutectic Solvent (chlorine chloride:oxalic acid), with fiber diameter and crystalinity index (CI) values of 80.37±1.06 nm and 85.66% respectively. Nanofibril cellulose was successfully functionalized with silver nanoparticles (AgNPs) using phycocyanin as a reducting agent. The aldehyde functional group (C=O) at the wavenumber of 1729 cm-1 in nanocellulose successfully bonded with AgNPs. Alginat hydrogel immobilized with 20% CNF/AgNPs treatment exhibited the highest antibacterial activity against Gram-negative bacterium Pseudomonas aeruginosa, while the antibacterial activities against Gram-positive Propionibacterium acne and Staphylococcus aureus did not significantly differ from other treatment. Immobilized of CNF/AgNPs in alginate hydrogel holds potential for application as an antibacterial wound dressing.
Keyword: DES, Fikosianin, Nanopartikel perak, Nanoselulosa, Rumput laut, Wound dressing

Judul: Synthesis of Alginate Hydrogel Incorporated with Nanocellulose from Solid Waste Agar Industry as A Wound Dressing
Abstrak: Hydrogels used in wound dressings must possess specific characteristics. The isolation of nanocellulose from the solid waste agar industry using deep eutectic solvents (DES) and its incorporation into alginate hydrogel as a wound dressing candidate have not been observed thus far. The objective of this study was to produce nanocellulose from the solid waste agar industry using different hydrated deep eutectic solvents (DES) and investigate the properties of alginate-incorporated nanocellulose (ALG-CEL) hydrogels as wound dressing candidates. This research was carried out by sample preparation and pretreatment of the solid waste agar industry, cellulose nanofibrillation, and hydrogel synthesis using selected nanocellulose with concentrations of 0.1, 0.3, and 0.6% (w/v). Pretreated solid waste contains cellulose and high ash content. The selected nanocellulose exhibited the highest yield, nanoscale fiber shape, and type-I cellulose with high crystallinity in the ChCl:urea treatment. The NC6 hydrogel showed the best characteristics, with a high gel content, swelling degree, tensile strength, and slow cumulative release. A controlled-release mechanism was identified for all treatments. The drug release kinetics of the ALG-CEL hydrogel fulfilled the Korsmeyer-Peppas model with the Fickian diffusion type. Nanocellulose from the solid waste agar industry improved the characteristics of alginate hydrogels and delivered drugs.
Keyword: alginate, deep eutectic solvents, hydrogel, solid waste agar industry, wound dressing

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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