Judul: Synthesis and Characterization of ZnO Nanoparticles with Pectin as a Capping Agent
Abstrak: Nanopartikel seng(II) oksida dapat disintesis melalui berbagai metode. Metode sintesis berpengaruh terhadap sifat dan karakteristik nanopartikel ZnO yang dihasilkan. Metode yang digunakan pada penelitian ini adalah presipitasi dan hidrotermal dengan perbedaan urutan penambahan reagen. Akan tetapi, selama proses hidrotermal, peluang terjadi agregasi sangat tinggi, sehingga diperlukan pula penggunaan capping agent. Oleh karena itu, penelitian ini bertujuan menyintesis nanopartikel ZnO menggunakan pektin sebagai capping agent melalui metode presipitasi dan hidrotermal, serta mengetahui pengaruh urutan penambahan reagen terhadap nanopartikel ZnO-pektin yang diperoleh. Nanopartikel ZnO yang diperoleh dikarakterisasi menggunakan XRD dan SEM. ZnO-pektin hasil sintesis OH⁻ dropwise memiliki ukuran yang lebih kecil dibandingkan dengan ZnO-pektin Zn²⁺ dropwise. Dengan demikian, pektin sebagai capping agent terbukti dapat mengontrol ukuran partikel ZnO melalui perbedaan urutan penambahan reagen., Zinc(II) oxide nanoparticles can be synthesized through a variety of methods. The synthesis method affects the properties and characteristics of the ZnO nanoparticles produced. The methods used in this study are precipitation and hydrothermal with different sequences of adding reagents. However, during the hydrothermal process, the chance of aggregation is very high, so the use of capping agents is also necessary. Therefore, this study aims to synthesize ZnO nanoparticles using pectin as a capping agent through precipitation and hydrothermal methods, and determine the effect of the sequence of addition of reagents on the ZnO-pectin nanoparticles obtained. The obtained ZnO nanoparticles were characterized using XRD and SEM. ZnO-pectin synthesized by OH⁻ dropwise has a smaller size compared to ZnO-pectin Zn²⁺ dropwise. Thus, pectin as a capping agent is proven to control ZnO particle size through the order of reagents additions.
Keyword: hydrothermal, nanoparticles, precipitation, zinc(II) oxide

Judul: Sintesis dan Karakterisasi Nanopartikel ZnO dengan Variasi Suhu Kalsinasi dan Penambahan Surfaktan menggunakan Metode Kopresipitasi Kimia
Abstrak: ZnO merupakan oksida logam yang memiliki karakteristik yang menarik dengan energi celah pita yang lebar. Penelitian ini bertujuan menyintesis ZnO dengan metode kopresipitasi dan mengkarakterisasi menggunakan berbagai instrumentasi. Perlakuan variasi suhu kalsinasi dilakukan agar dihasilkan partikel dengan ukuran dan tingkat kristalinitas yang baik. Penambahan surfaktan polivinil pirolidon (PVP) pada saat sintesis ZnO bertujuan mencegah terjadinya aglomerasi. Karakterisasi ZnO menggunakan spektroskopi ultraviolet-tampak (UV-Vis), difraksi sinar-X (XRD), spektroskopi inframerah transformasi fourier (FTIR), dan mikroskop elektron pemayaran (SEM). Hasil penelitian menunjukkan bahwa nilai celah pita ZnO meningkat seiring dengan kenaikan suhu. ZnO yang disintesis pada suhu kalsinasi 800 °C memiliki struktur wurtzit heksagonal. Ukuran kristal ZnO adalah 45,64 nm, sedangkan ZnO-PVP sebesar 40,37 nm. Tingkat kristalinitas ZnO terbaik adalah 61,34%. Spektrum FTIR menunjukkan serapan ZnO pada daerah sidik jari. Mikrograf SEM memperlihatkan bahwa ZnO tanpa penambahan PVP mengalami aglomerasi. ZnO hasil sintesis menunjukkan aktivitas antibakteri dengan terbentuknya zona hambat., ZnO is a metal oxide that has special characteristics with a wide band gap energy. This study aims to synthesize ZnO by coprecipitation method and to characterize it using various instrumentation techniques. The calcination temperature variation treatment was carried out in order to produce particles with good size and crystallinity level. The addition of polyvinyl pyrrolidone (PVP) surfactant during the synthesis of ZnO aims to prevent agglomeration. ZnO characterization used visible- ultraviolet spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), and scanning electron microscopy (SEM). The result showed that the value of the ZnO band gap increased with increasing temperature. ZnO synthesized at a calcination temperature of 800 °C has a hexagonal wurtzite structure. The crystal size of ZnO is 45,64 nm, while that of ZnO-PVP is 40,37 nm. The best ZnO crystallinity level is 61,34%. The FTIR spectrum shows ZnO absorption in the fingerprint region. SEM micrographs showed that ZnO without the addition of PVP agglomerated. The synthesized ZnO has antibacterial activity which is indicated by the formation of an inhibition zone.
Keyword: antibacterial, coprecipitation, polyvinyl pyrrolidone, temperature, ZnO

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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