The effect of different rare earth oxides on mechanical and optical properties of hot pressed α/β-Sialon ceramics

The effect of Y₂O₃ and different REOs (La₂O₃, Nd₂O₃ and Er₂O₃) on mechanical and optical properties on Sialon ceramics was studied. Duplex α/β-Sialon ceramics were revealed by XRD patterns in sintered body. α-Sialon phase was increased abruptly with the addition of Y₂O₃ and different REOs. Mechanical properties were also increased with the addition of REOs as compared without REOs. The crystallization at the triple junction with Y₂O₃ added Sialon was observed by TEM, which may be related to the slow cooling rate in hot press sintering process. Slow cooling rate causes the crystallization of glassy phase that occurred in grain boundaries and triple junctions. Crystallization of glassy phase enhances the mechanical properties of the material. Y₂O₃ had the positive effect on densification and mechanical properties. Mg-α/β-Sialon composite shows higher light transmission in NIR region than any other composition but better mechanical properties were shown by other compositions.     

Investigation of thermally stimulated properties of SHI beam irradiated polycarbonate/polystyrene double layered samples

The double layered samples of polycarbonate/polystyrene (PC/PS) have been prepared by solvent casting method and irradiated with 55 MeV C⁵⁺ beam at different ion fluences range from 1 × 10¹¹ to 1 × 10¹³ ion/cm². The effect of swift heavy ion (SHI) beam in interfacial phenomena, phase change, dielectric relaxation, degradation temperature, stability, charge storage and transport mechanism of PC/PS pristine and irradiated double layered samples have been investigated by thermally stimulated discharge current (TSDC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). TSDC show α, β-relaxation peaks shifted to the lower temperatures side with increase of fluence. The activation energy and relaxation time decrease, while the depolarization current and charge released increase with increase in the ion fluences. DSC curve show the glass transition temperature (T_g) and heat capacity decreases with increase in the ion fluences. The TGA characteristics represent the thermal stability, which is found to be decreased with increase in the ion fluences.     

Cleaning of high sulfur Indian coal by oil agglomeration and leaching

The present paper reports an attempt for cleaning of high sulfur Indian coal with two consecutive steps of oil agglomeration at ambient temperature followed by leaching at various conditions. The physico-chemical characterizations of the raw and treated coal samples were carried out by using Fourier transform infrared (FTIR), FESEM, Thermogravimetric analysis and Differential Thermal Analysis (TGA-DTA), and petrographic techniques to assess the product quality. The petrographic and FTIR spectral analyses reveal reduction in different forms of sulfur contents in coals by the use of oil agglomeration and leaching. Scanning electron microscope morphology of the treated coal samples are attributed to the occurrence of the cavitations in the coal structure.     

Combustion behavior of KOH desulphurized coals assessed by TGA-DTG

This work presents the results obtained from the experimental study on the effects of KOH treatment and its combustion behavior of high sulfur Indian coal. Coal was treated with 5–20% KOH (v/v) concentration for 6–24 h reaction time to identify the effects of KOH treatment on coal properties. Experimental results showed that upto 36.79% of total sulfur can be removed from coal with 20% KOH concentration and 24 h contact time at atmospheric condition. However, gross calorific value of coal decreased from 6800 to 6084 kcal/kg due to removal of combustibles from coal. Combustion characteristics of treated coal were assessed by Thermo-gravimetric analysis/ Differential thermo-gravimetric (TGA/DTG analysis). Further various combustion kinetic parameters like ignition temperature, peak temperature, burnout temperature, activation energy (E), and pre-exponential factor (A) are estimated. Experimental results show that the ignition temperature of coal decreased from 321°C to 252°C, peak temperature decreased from 459°C to 409°C due to changes in the coal matrix after desulfurization. The activation energy of coal calculated decreased from 79 to 45 kJ/mol due to desulfurization using 20% KOH concentration and 24 h reaction time.     

Modelling the complex modulus strain relationship of asphalt binders

The authors present the results and analysis of amplitude sweep tests done on 10 different asphalt binders using dynamic shear rheometer. The test was done from 30 to 70°C using a spindle geometry of 25 mm diameter with 1 mm gap setting. Matching function concept coupled with a three stage optimization procedure has been used to propose a new model for evaluating the complex modulus of bitumen at any given temperature and strain level. The model has been validated and is found to be fairly accurate for different types of binders.     

Detection of latent fingerprints using luminescent Gd0.95Eu0.05PO4 nanorods

Lanthanide ions doped luminescent materials are widely studied for latent fingerprint detection. However, most of these materials are synthesized at very high temperatures and use UV C light for visualization, which is harmful to eye, skin, etc. Herein, the Gd_0.95Eu_0.05PO₄ nanorods synthesized by a simple co-precipitation method at 185 °C were reported for latent fingerprint visualization under 395 nm light. The Gd_0.95Eu_0.05PO₄ nanomaterial has monoclinic crystal structure and shows rod-shaped morphology. Further, these Gd_0.95Eu_0.05PO₄ nanorods exhibit excellent photoluminescence properties and strong fuchsia emission under UV light. These nanorods have been employed for developing latent fingerprints on various porous and non-porous substrates by the powder dusting technique, which exhibits clear and well defined details with high contrast, selectivity and sensitivity under 395 nm UV light. Latent fingerprints developed after 72 h of their deposition also show clear contrast with these nanorods. Therefore, the Gd_0.95Eu_0.05PO₄ nanorods can be used for latent fingerprint visualization applications.     

Machine Learning Assisted Analysis,Prediction, and Fabrication of High-Efficiency CZTSSe Thin Film Solar Cells

The Earth-abundant element-based Cu₂ZnSn(S,Se)₄ (CZTSSe) absorber is considered as a promising material for thin-film solar cells (TFSCs). The current record power conversion efficiency (PCE) of CZTSSe TFSCs is ≈13%, and it's still lower than CdTe and CIGS-based TFSCs. A further breakthrough in its PCE mainly relies on deep insights into the various device fabrication conditions; accordingly, the experimental–oriented machine learning (ML) approach can be an effective way to discover key governing factors in improving PCE. The present work aims to identify the key governing factors throughout the device fabrication processes and apply them to break the saturated PCE for CZTSSe TFSCs. For realization, over 25,000 data points were broadly collected by fabricating more than 1300 CZTSSe TFSC devices and analyzed them using various ML techniques. Through extensive ML analysis, the i-ZnO thickness is found to be the first, while Zn/Sn compositional ratio and sulfo-selenization temperature are other key governing factors under thin or thick i-ZnO thickness to achieve over 11% PCE. Based on these key governing factors, the applied random forest ML prediction model for PCE showed Adj. R² = >0.96. Finally, the best-predicted ML conditions considered for experimental validation showed well-matched experimental outcomes with different ML models.     

Touchy feely vectors: A compensatory design approach to support model-based reasoning in developing country classrooms

Educational technology designs in developing countries mostly focus on making knowledge resources widely available, through MOOCs, repositories and computer-based tutoring. The use of digital media for cognitive augmentation, particularly interactive designs that help learners understand modelling topics in STEM, is underexplored. We report a 3-year design study examining this potential in the Indian context, testing two iterations of an interactive system, Touchy-Feely Vectors (TFV). The design supports learning vectors, a modelling topic pre-university students struggle with. Virtual lesson-plans were co-designed with teachers to augment — but not replace — their existing practices, and to address classroom and resource constraints. Pre-post testing of TFV-1 (a computer-based prototype) showed that it helped students develop a more integrated vector concept, and improved their reasoning. Field-implementation of TFV-2 (a textbook-linked touch-screen based design) in 6-classrooms (3-Control, N=135; 3-Experimental, N=131) showed that it fostered cognitive engagement in average-students and geometry-algebra integration (model-based reasoning) in good-students. These results, along with a requirements analysis based on textbooks, indicate that the interaction possibilities supported by different representational media critically shape student reasoning. The study also illustrates a systematic approach to design and test digital media systems that support cognitive augmentation in developing countries.