Judul: Cellulose-based Hydrogel from Oil Palm Empty Fruit Bunch Potential as Stem Cell Encapsulating Agent
Abstrak: Produk hasil dari kelapa sawit adalah salah satu komoditas unggulan Indonesia yang terbaharukan, bernilai ekonomi tinggi, dan tergolong dalam prioritas industri nasional. Peningkatan volume industri kelapa sawit akan meningkatkan hasil samping industri berupa tandan kosong yang berpotensi dimanfaatkan sebagai produk inovasi. Penelitian ini membuat hidrogel selulosa menggunakan tandan kosong kelapa sawit dan menelaah potensinya sebagai agen enkapsulasi sel punca. Isolasi selulosa menghasilkan produk dengan bobot molekul rerata senilai 2716,48 g/mol dengan kadar lignin akhir mencapai 0,62%. Sintesis natrium karboksimetilselulosa berhasil dilakukan dan dibuktikan dengan muncul serapan khas gugus karboksilat pada spektrum serapan inframerah. Hidrogel dibuat dengan menggunakan selulosa, natrium karboksimetilselulosa, dan epiklorohidrin. Hidrogel memiliki nilai daya serap air dengan rentang 237–711%. Salah satu aplikasi dari hidrogel ini adalah material enkapsulasi sel punca yang berpotensi digunakan dalam bidang kedokteran regeneratif. Hidrogel dari limbah sawit ini berpotensi memiliki sifat yang mirip dengan hidrogel komersial dalam mendukung pertumbuhan sel punca dan mempercepat regenerasi sel pada jaringan yang rusak., Oil palm products are one of the major commodities in Indonesia that is renewable, high in economic value, and listed in national industry priority. The increasing volume of the palm oil industry will increase the industrial side product in the form of empty fruit bunches that can be utilized as innovation. This research focuses on preparing cellulose-based hydrogel from oil palm empty fruit bunch and studying its potential as a stem cell encapsulating agent. The product of cellulose isolation had an average molecular weight of 2716.48 g/mol with a final lignin concentration of 0.62%. Synthesis of sodium carboxymethylcellulose was considered successful and proven by the appearance of the peak in the infrared absorption spectrum specific to the carboxylic group. Hydrogel was made from cellulose, sodium carboxymethylcellulose, and epichlorohydrin. The hydrogel had a water uptake value of 237–711%. One of the hydrogel applications is a stem cell encapsulating agent potential to be used in regenerative medicine. This hydrogel from palm waste has the potential to have properties similar to commercial hydrogel in supporting the growth of stem cells and accelerating cell regeneration in damaged tissues.
Keyword: enkapsulasi sel, hidrogel, sel punca, selulosa, TKKS

Judul: Sintesis Hidrogel Berbasis Selulosa dari Limbah Padat Industri Agar sebagai Scaffold Imobilisasi Enzim
Abstrak: Hidrogel berbasis polisakarida terbuat dari selulosa yang tersebar merata dalam matriks alginat melalui proses ikatan silang. Limbah padat pengolahan agar memiliki kandungan selulosa yang cukup tinggi. Sintesis hidrogel dengan penambahan selulosa limbah agar sebagai scaffold untuk imobilisasi enzim belum pernah dilakukan. Penelitian bertujuan untuk mendapatkan selulosa dengan ukuran berbeda dari limbah padat pengolahan agar, mengkarakterisasi hidrogel berbasis selulosa dengan ukuran berbeda, dan menentukan pelepasan enzim yang keluar dari hidrogel berbasis selulosa. Tahapan penelitian meliputi persiapan sampel, hidrolisis selulosa, dan sintesis hidrogel dengan variasi makroselulosa (0,5%, b/v) serta mikroselulosa (0,24, 0,48, dan 0,96%, (b/v)). Kadar selulosa diperoleh sebanyak 16,46% dengan satu ukuran makromolekul 10-200 µm sedangkan setelah dihidrolisis menjadi mikroselulosa dengan diameter serat sebesar 597,23 nm. Hidrogel alginat-selulosa menghasilkan rasio swelling dan fraksi gel terbaik sebesar 91,67 ± 11,8% dan 96,57 ± 0,05%. Perlakuan tersebut menghasilkan efektivitas pelepasan enzim terendah pada waktu ke-1 jam sebesar 11,80% dan mencapai puncak sebesar 97,12% pada waktu ke-24 jam. Selulosa dari limbah padat industri pengolahan agar dapat memperbaiki karakteristik hidrogel alginat. Hidrogel alginat-selulosa dapat digunakan sistem pengontrol enzim yang dapat diaplikasikan pada bidang pengolahan makanan dan bioproses., Polysaccharide-based hydrogel is made of cellulose dispersed in an alginate matrix through a cross-linking process. Solid waste of the agar industry has a fairly high cellulose content. The synthesis of hydrogel with the addition of waste cellulose agar as a scaffold for enzyme immobilization has never been done. The aim of the research was to obtain cellulose of different sizes from solid waste from agar processing, characterize cellulose-based hydrogel of different sizes, and to control the released enzyme from the hydrogel. The research includes sample preparation, cellulose hydrolysis, and hydrogel synthesis with addition of macro-cellulose (0.5%, w/v) and micro-cellulose (0.24, 0.48, 0.96% (w/v)). The cellulose content was obtained as much as 16.46% with a macromolecule size of 10-200 µm while after hydrolysis it became microcellulose with a fiber diameter of 597.23 nm. The alginate-cellulose hydrogel produced the best absorption and gel fraction of 91.67 ± 11.8% and 96.57 ± 0.05%, respectively. This treatment resulted in the lowest enzyme release effectiveness at 11.80% and reached a peak of 97.12% at 24 hours. Cellulose from the solid waste of the agar processing industry can improve the characteristics of the alginate. The alginate-cellulose hydrogel can be used as an enzyme control system that can be applied to food processing and bioprocessing.
Keyword: alginate, cellulose, enzyme imobilization, hydrogel, alginate, cellulose, enzyme imobilization, hydrogel

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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