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The Partnership for 21st Century Skills emphasizes the importance of reflective practices to develop critical thinking skills and motivation in students. The aim of this study was to examine the effect of reflective learning practices on undergraduate students' critical thinking skills and motivation during chemistry course. In this study, a quasi-experimental design with one group pretest-posttest was applied, using convenience sampling to select a study group of 30 undergraduate students. In the experimental group, reflective learning practices were implemented. DOT-CCTTv3 (Danczak-Overton-Thompson Chemistry Critical Thinking Test) was used as the data collection tool. IMMS questionnaire was also used to get feedback about reflective learning practices in classroom and to what extent these practices affect their motivation. Descriptive statistical techniques such as mean and standard deviation were calculated, paired sample t test was used to determine the mean difference between the pretest and posttest scores of the groups. This difference was found to be in favor of the experimental group. In the study, when the pretest and posttest scores of the experimental group were checked, a significant difference was found between the DOT-CCTTv3 pretest and posttest mean scores. The results of IMMS questionnaire showed that all four factors greatly affect the motivation of students after reflective learning practices. Based on these finding, it is concluded that reflective learning practices have a positive effect on students' critical thinking skills and motivation. It is recommended that in regular curricula of schools reflective learning practices should be practiced including, reflective dialogue, group discussions, self- evaluation, thinking aloud for enhancing critical thinking learning comprehension among students. To keep students engaged and motivated throughout the course, teachers should ensure that they use problem-based approach, and developments in real life. [ABSTRACT FROM AUTHOR]

Abstract Non-invasive photoplethysmography (PPG) technology was developed to track heart rate during motion. Automated analysis of PPG has made it useful in both clinical and non-clinical applications. However, PPG-based heart rate tracking is a challenging problem due to motion artifacts (MAs) which are main contributors towards signal degradation as they mask the location of heart rate peak in the spectra. A practical analysis system must have good performance in MA removal as well as in tracking. In this article, we have presented state-of-art techniques in both areas of the automated analysis, i.e., MA removal and heart rate tracking, and have concluded that adaptive filtering and multi-resolution decomposition techniques are better for MA removal and machine learning-based approaches are future perspective of heart rate tracking. Hence, future systems will be composed of machine learning-based trackers fed with either empirically decomposed signal or from output of adaptive filter.

Abstract Phonocardiogram (PCG) signal represents recording of sounds and murmurs resulting from heart auscultation. Analysis of these PCG signals is critical in diagnosis of different heart diseases. Over the years, a variety of methods have been proposed for automatic analysis of PCG signals in time, frequency, and time-frequency domains. This paper presents a comprehensive survey of different methods proposed for automatic analysis of PCG signals with the objective to evaluate the current state-of-the-art and to determine the potential domains of effective analysis. An important aspect of our contribution is that the review is carried out as a function of domains of analysis rather than simply discussing different methods. Our method further splits analysis into pre-processing, localization, and classification, and details are presented in terms of techniques and classifiers used during these phases. Finally, results are summarized for normal heart beat, noisy heart beat, and different pathologies using metrices like accuracy and detection rate. In addition to time and frequency domain, time-frequency based methods including wavelet, empirical mode decomposition (EMD) and time-frequency representation (TFR) are selected for detailed analysis. The review concludes that the time-frequency representations like EMD and wavelets represent areas of exploration in future along with perspective of using different time-frequency techniques together.

The creation of hydrogen by photocatalytic water splitting is a core research area in the worldwide attempts to discover a valid substitute for fossil fuels. Here, van der Waals CdO/PtS2 heterostructures for photocatalytic water splitting with excellent carrier separation and light absorption are reported based on first-principles calculations. Heterostructures with different stacking arrangements, CdO/PtS2-A and CdO/PtS2-B, possess suitable band edges for photocatalytic water splitting. The type-II band alignment with an intrinsic electric field produces efficient resistance to photo-induced charge carrier recombination. The charge carriers are more highly competent to reach the surface and participate in the reaction, which subsequently improves the photocatalytic performance due to a much smaller effective mass of electrons and holes. Moreover, the heterostructures exhibit enhanced optical absorption with an enormous absorption coefficient (105 cm−1) for absorption over a wide range of the visible spectrum compared to monolayers, which represents an efficient boost in photocatalytic activity. Our results demonstrate that CdO/PtS2 is an auspicious and exceptional photocatalyst for solar water splitting. [ABSTRACT FROM AUTHOR]

First-principles calculations have been employed here to investigate the optical and electrical properties of experimentally synthesized Mo(W)S2-SnO2 vdW heterostructures [J. Phys. Chem. C 2020, 124, 1, 647–652, Chem. Phys. 2019, 525, 110398]. Rigorous dynamical stability assessments confirm structural robustness, evident in phonon dispersion and AIMD simulations at 500 K. The interfacial binding energy values reflect the stability of our simulated heterostructures. With intrinsic type-II band alignment and direct band gaps of 1.21eV (MoS2-SnO2) and 1.003eV (WS2-SnO2), these heterostructures emerge as promising candidates for high-efficiency optical devices. Higher static dielectric constants in comparison with numerous heterostructures signify low charge carrier recombination rates, enhancing practical appeal. Optical analyses reveal substantial visible and ultraviolet (UV) spectrum absorption, while MoS2-SnO2 and WS2-SnO2 heterostructures exhibit photoelectric conversion efficiencies of 15.08% and 13.65%. A thorough examination of optical characteristics provides a comprehensive understanding of positioning Mo(W)S2-SnO2 vdW heterostructures for advanced optoelectronic devices. [ABSTRACT FROM AUTHOR]

Low cost and highly efficient two dimensional materials as photocatalysts are gaining much attention to utilize solar energy for water splitting and produce hydrogen fuel as an alternative to deal with the energy crisis and reduce environmental hazards. First principles calculations are performed to investigate the electronic, optical and photocatalytic properties of novel two dimensional transition metal dipnictide XP 2 (X = Ti, Zr, Hf) monolayers. The studied single layer XP 2 is found to be dynamically and thermally stable. TiP 2 , ZrP 2 and HfP 2 systems exhibit semiconducting nature with moderate indirect band gap values of 1.72 eV, 1.43 eV and 2.02 eV, respectively. The solar light absorption is found to be in energy range of 1.65-3.3 eV. All three XP 2 systems (at pH = 7) and the HfP 2 monolayer (at pH = 0) that straddle the redox potentials, are promising candidates for the water splitting reaction. These findings enrich the two dimensional family and provide a platform to design novel devices for emerging optoelectronic and photovoltaic applications., Competing Interests: There is no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Two-dimensional heterostructures formed by stacking layered materials play a significant role in condensed matter physics and materials science due to their potential applications in high-efficiency nanoelectronic and optoelectronic devices. In this paper, the structural, electronic, and optical properties of SiC/CrS 2 van der Waals heterostructure (vdWHs) have been investigated by means of density functional theory calculations. It is confirmed that the SiC/CrS 2 vdWHs is energetically and thermodynamically stable indicating its great promise for experimental realization. We find that the SiC/CrS 2 vdWHs has a direct-band gap and type-II (staggered) band alignment, which can effectively separate the photo-induced electrons and holes pairs and extend their life time. The carrier mobilities of electrons and holes along the armchair and zigzag directions are as high as 6.621 × 10 3 and 6.182 × 10 4  cm 2  V -1  s -1 , respectively. Besides, the charge difference and potential drop across the interface can induce a large built-in electric field across the heterojunction, which will further hinder the electron and hole recombination. The SiC/CrS 2 vdWHs has enhanced optical absorption capability compared to individual monolayers. This study demonstrates that the SiC/CrS 2 vdWHs is a good candidate for application in the nanoelectronic and optoelectronic devices., (© 2021 IOP Publishing Ltd.)