Judul: Pemanfaatan Tanin dari Kulit Kayu Acacia Mangium sebagai Pewarna Alami dengan Sifat Antibakteri
Abstrak: Tanin merupakan kelompok senyawa polifenol yang banyak terdapat pada kulit kayu. Hasil ekstraksi dari tanin dapat memberikan warna sehingga dapat dimanfaatkan sebagai pewarna alami. Sebagai agen pewarna alami, tanin memiliki aktivitas antioksidan dan antibakteri. Penelitian ini bertujuan untuk memanfaatkan tanin dari limbah kulit kayu untuk dijadikan pewarna alami dengan sifat antibakterti yang dapat mengurangi dampak buruk dari pewarna sintetis terhadap pencemaran air. Tanin dilarutkan menggunakan air dengan variasi suhu. Beberapa pengujian komponen kimia tanin diantaranya: fenolik dan analisis lanjut fenolik berupa Py-GCMS, antioksidan, dan antibakteri. Ekstraksi tanin diperbanyak pada suhu optimal berdasarkan pertimbangan pengujian. Pengaplikasian tanin ke kain dengan ditambahkan mordan tawas, lalu kain diuji aktivitas antibakteri. Kerusakan struktur bakteri dianalisis di bawah FESEM. Suhu 90 ᵒC merupakan suhu terbaik utnuk melakukan perbanyakan ekstrak tanin. Kain yang sudah diaplikasikan dengan tawas dan tanin menunjukkan aktivitas antibakteri yang kuat dengan diameter (1–2) cm., Tannins are a group of polyphenolic compounds that are widely found in bark. The extraction of tannins can provide color so that it can be used as a natural dye. As a natural coloring agent, tannins have antioxidant and antibacterial activities. This study aims to utilize tannins from bark waste to be used as natural dyes with antibacterial properties that can reduce the adverse effects of synthetic dyes on water pollution. Tannins are dissolved using water with temperature variations. Some tests of tannin chemical components include: phenolic and further analysis of phenolic in the form of Py-GCMS, antioxidant, and antibacterial. Tannin extraction was propagated at the optimal temperature based on testing considerations. Application of tannin to fabric by adding alum mordant, then the fabric was tested for antibacterial activity. Bacterial structure damage was analyzed under FESEM. The temperature of 90 ᵒC was the best temperature to propagate the tannin extract. The fabric applied with alum and tannin showed strong antibacterial activity with a diameter of (1-2) cm.
Keyword: antibakteri, ekstraksi, mordan, tanin

Judul: Fraksinasi Lignin dan Aplikasinya pada Kain sebagai Agen Antibakteri
Abstrak: Lignin mengandung gugus hidroksil fenolik yang dapat digunakan sebagai zat antibakteri alami. Berdasarkan penelitian sebelumnya, lignin memiliki sifat antibakteri yang baik pada bakteri gram positif. Akan tetapi, struktur lignin yang kompleks, heterogen, dan hidrofobik menyebabkan sulitnya aplikasi tersebut. Oleh karena itu penelitian ini bertujuan menghasilkan lignin yang bersifat hidrofilik dengan aktivitas antibakteri yang tinggi. Selain itu, penelitian ini bertujuan untuk menganalisis pengaruh tawas terhadap ketahanan sifat antibakteri kain berlapis lignin setelah pencucian. Pada penelitian ini, fraksinasi organosolv kayu Acacia crassicarpa menggunakan pelarut aseton, air, dan n-heksan. Kelarutan lignin diuji untuk mengetahui sifat hidrofiliknya. Kemudian sifat kimia lignin terfraksinasi diuji dengan FTIR, Py-GCMS, TGA, DSC, dan total phOH. Sedangkan aktivitas antibakteri dievaluasi dengan metode difusi agar terhadap bakteri S.aureus, S. epidermidis, P. acnes, dan B. subtilis. Aplikasi lignin pada kain rami menggunakan tawas sebagai agen pengikat silang. Hasil penelitian menunjukan bahwa fraksinasi organosolv mengahasilklan lignin bersifat lebih larut air dengan nilai kelarutan sebesar 70%, S/G rasio 1,56 dan total phOH 12,12 mmol/g. Total phOH dan S/G rasio diduga berkorelasi positif dengan aktivitas antibakteri sehingga memiliki nilai zona bening yang lebih besar (0,8-1,4 cm). Selain itu, kain berlapis lignin organosolv yang telah di cuci memiliki ketahanan terhadap bakteri uji dengan nilai rata-rata diameter zona bening sekitar 0,1-0,4 cm., Phenolic hydroxyl groups found in lignin can be employed as organic antibacterial agents. According to earlier studies, lignin effectively combats gram positive bacteria. However, the application is challenging due to the lignin's complicated, heterogeneous, and hydrophobic structure. As a result, the goal of this project is to create hydrophilic lignin with strong antibacterial properties. The study also seeks to examine how alum affects the durability of the antibacterial capabilities of lignin-coated fabrics after washing. In this study, acetone, water, and n-hexane were utilized as solvents for the organosolv fractionation of Acacia crassicarpa wood. Testing the solubility of lignin revealed that it is hydrophilic. Following that, FTIR, Py-GCMS, TGA, DSC, and total phOH were used to examine the chemical characteristics of fractionated lignin. The agar diffusion method was used to assess the antibacterial activity in the meantime against the bacteria S. aureus, S. epidermidis, P. acnes, and B. subtilis. applying lignin using alum as a crosslinking agent to hemp textiles. According to the findings, lignin generated through organosolv fractionation is more water soluble, having a solubility value of 70%, a S/G ratio of 1,56, and a total pH of 12,12 mmol/g. They have a higher clear zone value because total phOH and S/G ratios are believed to have a favorable link with antibacterial activity (0,8-1,4 cm). Additionally, the textiles coated with lignin and treated with organosolv demonstrated resistance to the test microorganisms with an average clear zone diameter of between 0,1 cm and 0,4 cm.
Keyword: antibacterial, clear zone, fractionation, lignin, organosolv

Judul: Analysis of Unequal Income Distribution with Cobb-Douglas Production Function
Abstrak: This paper studies the economic growth model by Moav (2002). Moav model shows the existence of unequal income distribution between low-income with high-income community. That kind of unequal income distribution is caused by uneven distribution of income. On this Moav model, there is one area called the threshold. Threshold becomes a benchmark to determining whether a society is categorized into low- or high- income community. The production function used in this paper is the Cobb-Douglas function. The dynamics of this model is described as difference equation of low-income, threshold, and high-income community. Simulation study on the model is carried out using Maple 13 and Mathematica 7.0 software. Overall, from the observed case, high-income community will reach a stable condition earlier, followed by the threshold, and then the low-income community.
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