Judul: Aktivitas Antioksidan Zeolit Alam Terpilar-TiO2
Abstrak: Utilization of zeolite in Indonesia is still limited. However, in the field of agriculture and environmental processing technology, zeolites are widely known as reliable adsorbent materials. This study aimed to determine the antioxidant activity of TiO2-pillared zeolite by using 1,1-diphenyl-2-picrylhidrazyl. The natural zeolites were activated with variation of acid concentration and heating temperature. The pillarization product of the best activated zeolite were characterized by X-ray diffractometer (XRD) and scanning electron microscope (SEM-EDX). The antioxidant activity of natural zeolite increased after being pillared with TiO2. XRD diffractogram showed that Sukabumi’s natural zeolite was a mixture of clinoptilolite and mordenite types with 53.03% crystallinity, whereas the SEM-EDX result showed that the composition of TiO2 increased 13.82% in zeolite activated at 400 oC and 4.34% in zeolite activated with 2.0 M acid concentration. These increase promoted the antioxidant activity of 14.80% and 6.17%, respectively.
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Judul: Potensi Zeolit Alam Sebagai Antioksidan
Abstrak: Zeolite is an aluminosilicate mineral which are three dimensional frameworks in its structure, has cavities and channels connected to each other creating wide surface so that effective as an adsorbent. Besides, zeolite has negative charge, which can interact with charged compounds or molecules such as 1,1-diphenyl-2-picrylhydrazyl (DPPH). The aim of this research is to measure the activity of Indonesian natural zeolites from Banten, Lampung, Sukabumi, and Tasikmalaya to scavenge DPPH free-radical. Antioxidant activity test against DPPH performed on the untreated zeolite, temperature-activated zeolite, and acid-activated zeolite. The highest antioxidant activity was shown by Sukabumi zeolite, which was 85.56% when activated at 100 °C and 65.56% when activated with 1 M HCl. The results of scanning electrone microscopy and X-ray diffraction analysis showed that zeolites from Banten, Lampung, Sukabumi, and Tasikmalaya are clinoptilolite typ
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Judul: Pemodelan chord pada piano menggunakan metode fuzzy learning vector quantization
Abstrak: Seorang pemain piano pemula maupun autodidak umumnya belum melalui tahap latihan yang baik sehingga kemampuan untuk mengenali chord yang dimiliki masih kurang. Oleh karena itu, suatu sistem yang dapat mengenali chord untuk membantu proses pemahaman chord yang dimainkan dibutuhkan. Penelitian ini memodelkan chord yang terdiri atas 3 nada (triad) ke dalam beberapa kelas. Data yang digunakan dalam penelitian ini adalah 24 chord mayor dan minor. Data training dan data testing divariasikan dalam 4 model menggunakan 5-fold crossvalidation. Ekstraksi ciri akan dilakukan dengan metode Mel Frequency Cepstrum Coefficients, dan klasifikasi akan dilakukan dengan metode Fuzzy Learning Vector Quantization (FLVQ). Pemodelan FLVQ dilakukan dengan melakukan variasi pada learning rate serta koefisien fuzzyness. Penelitian ini telah berhasil membentuk model FLVQ dengan akurasi rata-rata 79.38% serta akurasi maksimum 100%. Akurasi maksimum dicapai dengan nilai learning rate α sebesar 0.05 dan koefisien fuzzyness β sebesar 0.05 menggunakan epoch sebanyak 20 pada FLVQ model 2.
Keyword: chord, FLVQ, MFCCs, modeling, note.