Ea Cahya Septia Mahen

Hydrogels represent a promising alternative for plant cultivation, offering excellent water and nutrient retention. This study reports the synthesis and characterization of an agarose-based hydrogel composite enhanced with eggshell powder (ESP). The hydrogel composites were prepared in four agarose-to-ESP ratios: 10:0 (Hyd-ES0), 10:1 (Hyd-ES1), 10:3 (Hyd-ES3), and 10:5 (Hyd-ES5). Fourier-transform infrared spectroscopy (FTIR) analysis revealed minimal peak shifts, indicating no significant chemical modifications. Characteristic ESP peaks were identified in the composite hydrogels, confirming the effective integration of ESP into the agarose matrix. The addition of ESP reduced the decomposition rate of the hydrogels and increased macromolecular stability. Density measurements indicated higher density with increasing ESP concentration, supported by enhanced crystal formation, as evidenced by more intense diffraction peaks in X-ray diffraction (XRD) patterns. Morphological analysis revealed that the porosity of the hydrogel, swelling, and weight-loss tests showed a decline in both properties with higher ESP content. Seed germination experiments demonstrated that stem, root, and leaf growth, as well as fresh and dry weights, were most optimal with the Hyd-ES1 hydrogel composite. Thus, Hyd-ES1 hydrogel exhibits significant potential as a medium for seed germination and plant growth.

Zero-dimensional Perovskite Magic-size Clusters play crucial roles in understanding and controlling nucleation and growth of semiconductor nanoparticles. However, their metastability behavior is a critical hindrance for reliable characterizations. Here, we report the first demonstration of using an excess amount of surface ligand and SiO₂ as novel passivation for synthesizing the magic-sized clusters (MSCs) by the Ligand-assisted reprecipitation method. A synergetic effect between an excessed surface ligand and SiO₂ inhibits the protonation and deprotonation reaction between amine-based and acid-based ligand, leading to enhanced PL stability. The obtained CH₃NH₃PbBr₃ PMSCs/SiO₂ retain 70% of its initial emission intensity in ambient conditions for 20 days. This passivation approach opens an entirely new avenue for the reliable characterizations of CH₃NH₃PbBr₃ PMSCs, which will significantly broaden their application for understanding and controlling nucleation and growth of semiconductor nanoparticles.

The effect of silica (SiO2) addition on optical properties of organometal halide perovskite PMMA composite film was studied. The organometal halide perovskite, MAPbBr3, was synthesis using ligand assisted re-precipitation (LARP) method, and then was compose to PMMA and SiO2 directly to make composite films. The absorbances, transmittances, and photoluminescence (PL) spectrum of the samples were characterised using UV Vis and PL spectroscopy. The result shows that the addition of silica leads blueshift on photoluminescence and absorbance spectra. The blue shift reveals one-dimensional confinement effect in perovskite.

This paper reports on the result of a preliminary study of utilization of a smartphone ambient light sensor for get the average speeds of motion along a straight line based on experiments. We attach a smartphone to a dynamics train that travels across multiple light sources where the distance is already set. The main source of this experiment is obtained from the luminosity curve obtained from free android applications. From the curve, we can get position information against time. So from the data we can get the value of average speed. Then the use of the smartphone light sensor in physics experiments can be done easily and fun.

This paper presents drag force analysis of free falling object using software tracker. We use video cupclips that have been embedded in this software. The video featured cupcakes to which hung a number of different paper clips were dropped simultaneously. We track the trajectory of free falling cupclips using the software to get the information of position, speed, and acceleration of each cupcake against time. From the data we get the value of drag forces and drag coefficients for each time. The result shows that the drag force value increased to almost constant value, otherwise the drag coefficient is reduced to almost constant values well. According to the results, the analyzed data has good agreement with the theory. Thus, software tracker can be used as media to learn drag force easily and inexpensively.

In this study, we have synthesized and applied the activated carbon fibbers from pyrolyzed cotton to adsorp fume pollutants. The activated carbon fibbers from cotton were synthesized using an oven with simple heating method at low carbonization temperature. The cotton was successfully turned into carbon within four hours at carbonization temperature of 250°C. The reults showed that activation process using KOH and NaOH significantly affected the functional groups, morphology, diameter, and porosity of the activated carbon fibbers.

In this paper, we report on a homemade optical spectrometer using diffraction grating and image processing techniques. This device was designed to produce spectral images that could then be processed by measuring signal strength (pixel intensity) to obtain the light source, transmittance, and absorbance spectra of the liquid sample. The homemade optical spectrometer consisted of: (i) a white LED as a light source, (ii) a cuvette or sample holder, (iii) a slit, (iv) a diffraction grating, and (v) a CMOS camera (webcam). In this study, various concentrations of a carbon nanoparticle (CNP) colloid were used in the particle size sample test. Additionally, a commercial optical spectrometer and tunneling electron microscope (TEM) were used to characterize the optical properties and morphology of the CNPs, respectively. The data obtained using the homemade optical spectrometer, commercial optical spectrometer, and TEM showed similar results and trends. Lastly, the calculation and measurement of CNP size were performed using the effective mass approximation (EMA) and TEM. These data showed that the average nanoparticle sizes were approximately 2.4 nm and 2.5 ± 0.3 nm, respectively. This research provides new insights into the development of a portable, simple, and low-cost optical spectrometer that can be used in nanomaterial characterization for physics undergraduate instruction.

ZnAl2O4: Mn4+ particle were synthesize using co-precipitation using NaOH and PVA as precipitating agent and surfactants, followed by microwave-assisted thermal treatment. The morphology properties and absorption spectral of particles were investigate using SEM and UV-Vis spectrometer. The results showed that the ZnAl₂O₄ particles has a spinel structure with various particle size. Absorption spectral exhibits that particle has a potential photo catalytic properties at visible light spectra, especially for the pollutant degradation.