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Background: E-learning is increasingly becoming a preference in higher education institutions worldwide; this is intended to assist educational institutions in achieving objectives to meet the proportion of individuals with their educational opportunities. Nevertheless, instructors and students frequently have concerns with their capacity to succeed in E-learning environments. Objectives: This study aimed to presents common eLearning challenges in regard to e-learning courses structure and its relations to various factors, for instance; students' autonomy, prior knowledge and experience, students-students dialogue, and students-instructor dialogue, and proposes solutions to these challenges based on the transactional distance theory. Moreover, this study presents evidence from Malaysian higher institutions based on theoretical models for e-learning course structure and its relations to the factors mentioned above. Methods: Data have been collected from 680 university learners all over Malaysia. Data were then examined using exploratory factor analysis, confirmatory factor analysis, and structural equation modelling employing Smart PLS 3.0 software. Results and conclusion: Research findings indicated that e-learning course structure was affected by all dimensions of overall path analysis findings: student autonomy, students background, student-instructor dialogue, and student-student dialogue. However, the e-learning course structure showed insignificant with students' prior experience. Implications: Implications for universities are discussed accordingly. Such findings provide vital support to the integrative association among collaborative control (CC) and transactional distance theory (TDT) regarding e-learning environments experience, which might support universities administrators in the higher education industry to implement, plan and evaluate online learning platforms applications in their institutions.

The use of online social networks (OSNs) has increasingly attracted attention from scholars' in different disciplines. Recently, student behaviors in online social networks have been extensively examined. However, limited efforts have been made to evaluate and systematically review the current research status to provide insights into previous study findings. Accordingly, this study conducted a systematic literature review on student behavior and OSNs to explicate to what extent students behave on these platforms. This study reviewed 104 studies to discuss the research focus and examine trends along with the important theories and research methods utilized. Moreover, the Stimulus-Organism-Response (SOR) model was utilized to classify the factors that influence student behavior. This study's results demonstrate that the number of studies that address student behaviors on OSNs have recently increased. Moreover, the identified studies focused on five research streams, including academic purpose, cyber victimization, addiction, personality issues, and knowledge sharing behaviors. Most of these studies focused on the use and effect of OSNs on student academic performance. Most importantly, the proposed study framework provides a theoretical basis for further research in this context.

Abstract The use of online social networks (OSNs) has increasingly attracted attention from scholars’ in different disciplines. Recently, student behaviors in online social networks have been extensively examined. However, limited efforts have been made to evaluate and systematically review the current research status to provide insights into previous study findings. Accordingly, this study conducted a systematic literature review on student behavior and OSNs to explicate to what extent students behave on these platforms. This study reviewed 104 studies to discuss the research focus and examine trends along with the important theories and research methods utilized. Moreover, the Stimulus-Organism-Response (SOR) model was utilized to classify the factors that influence student behavior. This study’s results demonstrate that the number of studies that address student behaviors on OSNs have recently increased. Moreover, the identified studies focused on five research streams, including academic purpose, cyber victimization, addiction, personality issues, and knowledge sharing behaviors. Most of these studies focused on the use and effect of OSNs on student academic performance. Most importantly, the proposed study framework provides a theoretical basis for further research in this context.

Triangular and hexagonal multilayer phosphorene quantum dots with armchair and zigzag terminations are investigated with the orthogonal tight-binding model. The effect of increasing the number of layers is revealed. The obtained results show that in a small size multilayer quantum dot, the edge states are as sensitive to the out-of-plane external electric fields as the edge states in a single layer dot to the in-plane external electric fields. The investigated optical absorption cross sections show that armchair phosphorene quantum dots have a regular behavior which should be useful for infrared detectors. In particular, it was found that in hexagonal armchair phosphorene dots, absorption peaks can be increased, decreased, or totally removed from the low-energy region depending on the orientation of the applied electric field. The effect of spurious doping can suppress the transitions < 0.4 eV, while the effect of the finite temperature is almost negligible. [ABSTRACT FROM AUTHOR]

Nanometric AgFeO2 and AgCrO2 delafossite were easily prepared by the flash auto-combustion method. The two main bands estimated from FTIR (Fourier-transform infrared) analysis were the tetrahedral A-site (573 cm−1 for AgFeO2, 630 cm−1 for AgCrO2) and the octahedral B-site (484 cm−1 for AgFeO2, 595 cm−1 for AgCrO2). This study is mainly focused on the elastic properties evaluated from the FTIR analysis and showed that AgCrO2 delafossite is more elastic than AgFeO2 delafossite. The elastic properties can be explained by studying the longitudinal and transverse velocities. Owing to the optical properties results, AgCrO2 delafossite is a promising material to be applied in optical devices. However, AgFeO2 delafossite is a promising material in magnetic applications because it showed a large switching field distribution by 9-fold more than that of AgCrO2 delafossite. Moreover, high-frequency applications were calculated from the magnetic analysis and showed that both samples could be applied in ultra-high microwave applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electronic and catalytic properties of group 15 clusters are studied using DFT. • Sp-and sp3-hybridized gases adsorbed physically while sp2-ones adsorbed chemically. • The clusters are semiconductors with band gaps (2.1−3 eV) tunable by the adsorption. • The overpotential (η) for oxygen evolution on the edges is lower than on the surface. • Sb-cluster has the lowest η, 0.31 v, due to moderate bonding with all intermediates. Density functional theory calculations are employed to investigate the electronic, adsorption, and catalytic properties of Bi-, Sb-, and As-nanoclusters. The stability of these clusters are confirmed by the obtained positive binding energies, the change in the free energy, and frequencies, also they can be grown on different substrates such as graphene and hexagonal boron nitride. They have energy gaps ranging from 2.1 to 3 eV that can be controlled by adsorption of different gases or molecules, for instance, adsorption of C 2 decreases the gap in Sb-18-a cluster from 2.7 eV to 0.8 eV. These clusters show also interesting adsorption properties where some gases are physically adsorbed (like, N2 and CH 4) while others are chemically adsorbed (O 2 and SO 2). In the first case, the linear N 2 molecule has a strong triple bond, from the sp-hybridization, that can't be broken through the interaction with the clusters, the same occurs also for the sp3-hybridized CH 4 with the strong sigma bonds. For the sp2-hybridized O 2 molecule, one of the relatively weaker double bond can be broken through the interaction to form another with the cluster. The oxygen evolution reaction (OER) on the edges of these clusters requires lower overpotential than their surfaces due to the moderate adsorption of O by one edge atom with respect to the strong adsorption by two surface atoms. Nanoclusters and quantum dots of Sb provide the best values for the overpotential due to moderate bonding that Sb atoms form with all intermediates not only O, namely overpotentials equal 0.31 and 0.39 V for the nanocluster and the quantum dots, respectively. This significant enhancement of the OER activity makes such clusters strong applicants for water oxidation catalysts. [ABSTRACT FROM AUTHOR]

Aims: The study is aimed to verify Aperio AT2 scanner for reporting on the digital pathology platform (DP) and to validate the cohort of pathologists in the interpretation of DP for routine diagnostic histopathological services in Wales, United Kingdom. Materials, Methods and Results: This was a large multicenter study involving seven hospitals across Wales and unique with 22 (largest number) pathologists participating. 7491 slides from 3001 cases were scanned on Leica Aperio AT2 scanner and reported on digital workstations with Leica software of e-slide manager. A senior pathology fellow compared DP reports with authorized reports on glass slide (GS). A panel of expert pathologists reviewed the discrepant cases under multiheader microscope to establish ground truth. 2745 out of 3001 (91%) cases showed complete concordance between DP and GS reports. Two hundred and fifty-six cases showed discrepancies in diagnosis, of which 170 (5.6%) were deemed of no clinical significance by the review panel. There were 86 (2.9%) clinically significant discrepancies in the diagnosis between DP and GS. The concordance was raised to 97.1% after discounting clinically insignificant discrepancies. Ground truth lay with DP in 28 out of 86 clinically significant discrepancies and with GS in 58 cases. Sensitivity of DP was 98.07% (confidence interval [CI] 97.57-98.56%); for GS was 99.07% (CI 98.72-99.41%). Conclusions: We concluded that Leica Aperio AT2 scanner produces adequate quality of images for routine histopathologic diagnosis. Pathologists were able to diagnose in DP with good concordance as with GS. Strengths and Limitations of this Study: Strengths of this study - This was a prospective blind study. Different pathologists reported digital and glass arms at different times giving an ambience of real-time reporting. There was standardized use of software and hardware across Wales. A strong managerial support from efficiency through the technology group was a key factor for the implementation of the study. Limitations: This study did not include Cytopathology and in situ hybridization slides. Difficulty in achieving surgical pathology practise standardization across the whole country contributed to intra-observer variations. [ABSTRACT FROM AUTHOR]

The electronic and adsorption properties of chemically modified square hexagonal boron nitride quantum dots are investigated using density functional theory calculations. The free energy and frequency calculations show that all the boron nitride flakes are stable before/after modification and metal adsorption. Edge modification significantly enhances the stability and interactivity of the flake. For instance, the free energy of binding decreases from −6.5 eV in the hydrogenated flake to −7.1 eV in the pristine one and the dipole moment increases from 4.5 D to 53.7 D, respectively. A wide spectrum of band gaps can also be achieved, where the band gap can be smoothly varied from ∼6 eV in edge fluorinated flakes to 0.2 in sulfurated ones. Six hydrated metals, Cd, Co, Cr, Cu, Fe, and Zn, are considered for adsorption by the flakes. The transition metals are highly selected by the flakes while heavy metals are weakly adsorbed. All hydrated metals are physically adsorbed by the edge and surface of hydrogenated flakes except Cu, which is chemically adsorbed. Chemical groups or elements attached to the flake strongly enhance the adsorption strength; the adsorption energy of hydrated Cr on the surface increases from 0.6 eV to 8.6 eV after attaching two COOH groups to the surface. Hydrogen evolution has also been observed through the adsorption process. The calculated low overpotential for the oxygen evolution reaction (0.52 V) and hydrogen adsorption strength (0.11 eV) for the hydrogen evolution reaction indicate that boron nitride quantum dots are not only potential candidates for the removal of different metals from wastewater but also for efficient water splitting. [ABSTRACT FROM AUTHOR]

In the present study, we prepared AgCrO2 delafossite at high annealing temperature 800 °C by flash auto-combustion technique which is an easy and a low-cost method. The objective of this study was to tailor the structural, magnetic and antimicrobial study of AgCrO2 delafossite at this high annealing temperature (800 °C) which can be used in the fascinating applications. The sample was examined using X-ray diffraction pattern to confirm its single-phase hexagonal structure. Moreover, the morphology was analyzed by the field-emission scanning electron microscopy to clarify that AgCrO2 delafossite was in the nanoscale range. The energy-dispersive X-ray analysis was performed to show the composition of the sample. The room-temperature magnetic hysteresis loop assured that the sample had superparamagnetic behavior. The investigated sample AgCrO2 delafossite can be considered to have a strong antibacterial activity against Gram-positive and Gram-negative bacteria. However, by studying the effect of AgCrO2 delafossite against fungi microorganism, no activity was detected using AgCrO2 delafossite. The promising application of this study is to add AgCrO2 delafossite to various drugs as an antibacterial agent. [ABSTRACT FROM AUTHOR]

The evolution of social commerce (s-commerce) has changed both businesses and customers. Therefore, understanding customer engagement behaviour in the s-commerce context has become a key competitive advantage for companies that aim to build a customer-centric business. The purpose of this study is to provide an in-depth review of customer engagement studies in the context of s-commerce. This study used a systematic literature review approach on customer engagement studies in the context of s-commerce. The results show that social theories and factors play a significant role in customer engagement along with technological factors. More importantly, drawn from the review results, a research framework was developed to show the factors that provide the greatest influence in customer engagement behavior. [ABSTRACT FROM AUTHOR]

Nanocrystalline Cr-doped Ni/Cd/Zn of general formula Ni0.7Cd0.1Zn0.2CrxFe2−xO4 (x= 0, 0.1, 0.3, 0.5, 0.7, 1) were synthesized by coprecipitation method. X-ray analysis (XRD) confirmed that the samples had a single-phase cubic spinel structure. The morphology was studied using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) to assure that the samples were in the nanoscale range. Spectroscopic analysis was carried out using UV-VIS-NIR spectroscopy for all samples. One can conclude that Ni0.7Cd0.1Zn0.2Cr0.5Fe1.5O4 had the most suitable energy bandgap that could be applied to the visible light region and many industrial applications. Moreover, this sample (Ni0.7Cd0.1Zn0.2Cr0.5Fe1.5O4) played an important role in the improvement of photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

AgFeO2 delafossite was successfully prepared by a facile and low-cost method which was flash auto-combustion technique. X-ray diffraction pattern (XRD) confirmed that the sample was in the nanosize range. Also, the morphology analyzed by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) clarified that AgFeO2 delafossite was in the nanoscale range. The composition of the sample was determined using energy dispersive X-ray (EDX) analysis. The magnetic properties assured that the sample had ferromagnetic behavior. The optical properties were measured for the investigated sample and the energy gap was 3.4 eV. The antimicrobial activities were screened against Gram positive and Gram negative bacteria and the results revealed a strong antibacterial activity of AgFeO2 delafossite. Moreover, Fungi activity was studied against Aspergillus flavus and Candida albicans and the results revealed that no activity by adding AgFeO2 delafossite had happened. The application of this study promotes the use of AgFeO2 as antibacterial agent. [ABSTRACT FROM AUTHOR]

In this study, we fabricate Cr-doped Ag nanoparticles (AgCrO2 and Ag0.5Cr2.5O4) by flash autocombustion method. XRD confirmed that the samples have a single-phase spinel structure. The morphology is studied using high-resolution transmission electron microscopy (HRTEM) to confirm that the samples are on nanoscale. The magnetic properties are studied using a vibrating sample magnetometer (VSM) at room temperature (300 K) and at low temperatures (200 and 100 K). Exchange bias has occurred for the investigated samples below room temperatures. The shifts have occurred in the horizontal directions which may be ascribed to the frozen spins in the samples. [ABSTRACT FROM AUTHOR]

This work reports a simple, novel, low-cost and eco-friendly synthesis of AgCrO2 nanoparticles and its double nanometric delafossite Ag2Cr2O4 nanoparticles. The rate of synthesis is much faster than other synthesis methods and this approach is suitable for production in large scale. It is the first time to report the double nanometric delafossite from AgCrO2 nanoparticles at such low temperature (250 °C) and it is suitable to be applied as photocathode in a dye-sensitized solar cell, antimicrobial and many technological applications. The as-synthesized AgCrO2 and Ag2Cr2O4 nanoparticles, including their crystal phases, morphologies, element compositions, magnetic and optical properties, have been systematically studied. By enhancing AgCrO2 nanoparticles to double nanometric delafossite Ag2Cr2O4 nanoparticles, a transformation of magnetic material type has happened from superparamagnetic to ferromagnetic behavior. The optical study revealed that Ag2Cr2O4 nanoparticles had larger values of reflectance, refractive index, real and imaginary parts of dielectric constant and optical conductivity than that of AgCrO2 nanoparticles. An Antimicrobial application had been studied for both samples. Ag2Cr2O4 nanoparticles had better antimicrobial application than that of AgCrO2 nanoparticles. [ABSTRACT FROM AUTHOR]