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Jurnal Fisika
Published by Universitas Negeri Semarang
ISSN : -     EISSN : 2684978X     DOI : https://doi.org/10.15294/jf
Core Subject : Science,
Physics
urnal Fisika coverage extends across the whole of physics, encompassing pure, applied, theoretical and experimental research, as well as interdisciplinary topics. Research areas covered by the journal include
Arjuna Subject : Fisika dan Astronomi - Fisika dan Astronomi (Lain-Lain)
Articles 22 Documents
 1   2   3 
Synthesis of Carbon Quantum Dots and Their Optical Properties Under Various Conditions Dhobi, Saddam; Hangsarumba, Surendra; Kamat, Raman Kumar; Yadava, Kishori; Gupta, Suresh Prasad
Jurnal Fisika Vol. 15 No. 2 (2025): Jurnal Fisika 15 (2) 2025
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jf.v15i2.33311

Abstract

Carbon quantum dots (CQDs) are nanomaterials that possess great optical properties, and they hold potential for being used in biosensing, imaging, and optoelectronics. The aim of this work is to synthesis, characterization and study the optical properties of CQDs under various condition. In the present work, CQDs have been prepared by mixing equal amount (citric acid and urea) and heating in microwave at 165 °C-180 oC for 2 min to obtained dark brown color. The dark brown power was characterizations using FTIR to confirmed the different functional groups such as –P–O, –S–O, – O–C, C=C C=N and CH2/CH3 (oxygenated-, nitrogenated- and aromatic-types), while XRD analysis indicated the valuable crystalline organic phases with heterogeneous functionality features. The optical properties were carried out in water and sugar solutions (100–155mg/dl) as function of CQDs concentration, temperature, frequency and UV activation times using a Theremino spectrometer. The fluorescence intensity was enhanced with the increase of citric acid and was quenched by urea. In sugar at higher CQD concentrations, intensity was decreased from molecular trapping and light scattering. The fluorescence intensity exhibited fluctuations in water during 60s with red and blue-shifts, and the maximum peak was at 545 nm. The intensity increased with decreasing CQD: water ratio and decreased at higher concentrations, because of absorption and scattering. The temperature and frequency have strong effects on the optical responses; the higher temperatures (58 °C) promote dispersed aggregates in finer particles which leads to more light transmission in addition to larger absorption values at higher frequencies. This demonstrated the tunable features of CQDs optical properties and might give suggestions for subsequent optimization for their applications in biosensing, imaging, and optoelectronics.
Development of Sound-Absorbing Composites Made from Water Hyacinth Waste and Recycled Cardboard Anastasya, Agitha; Widyaningsih, Ayu; Firmansyah, Lucky Fathoni
Jurnal Fisika Vol. 15 No. 2 (2025): Jurnal Fisika 15 (2) 2025
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jf.v15i2.37524

Abstract

Noise is a factor that can disrupt the comfort and effectiveness of daily activities, including learning. To address this issue, this study develops an environmentally friendly sound-absorbing material made from water hyacinth and cardboard, both of which possess natural porosity suitable for acoustic applications. This experimental research aims to determine the sound absorption coefficient of composite materials produced from various combinations of these wastes. Five composite variations were prepared: Sample A (4 g water hyacinth, 4 g cardboard, 8 g matrix), Sample B (5 g water hyacinth, 3 g cardboard, 8 g matrix), Sample C (3 g water hyacinth, 5 g cardboard, 8 g matrix), Sample D (4 g water hyacinth, 4 g cardboard, 9 g matrix), and Sample E (4 g water hyacinth, 4 g cardboard, 7 g matrix). The absorption coefficient was measured using an impedance tube. The results showed that each composition produced different absorption coefficients. Sample D, with a composite-to-matrix ratio of 7:9, had the highest sound absorption coefficient of 0.327 at a frequency of 100 Hz. Meanwhile, Sample E, with a composite-to-matrix ratio of 9:7, had the lowest coefficient of 0.014 at 350 Hz. The findings indicate that water hyacinth and cardboard can be utilized as sound-absorbing materials, with absorption coefficients ranging from 0.01 to 0.32, thereby meeting the ISO 11654 standard.

Page 3 of 3 | Total Record : 22

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