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Massive Online Open Courses (MOOCs) are a form of online learning that has become increasingly popular across the globe, yet they often suffer from low completion rates. This study aims to advance understanding of the Dropout Phenomenon in MOOCs through a qualitative case study conducted in Pakistan. The purpose of this research is to understand why learners drop out of MOOCs by identifying the factors that influence the decision of learners. Semi-structured interviews with MOOC participants were conducted and analysed who had enrolled in two MOOCs that had a high dropout rate. The responses from the interviews were categorised under three overarching themes: lack of motivation, perception of course content, and inability to manage time. Within those themes, several factors that affect course dropout rates were identified, including perceived rewards, difficulties in comprehension, academic and family commitments, and duration of the course. [ABSTRACT FROM AUTHOR]

Recently, ammonia is getting more attractive as a potential alternative fuel for future power generation and transportation purposes due to its ability to reduce consumption of fossil fuels, soot, CO 2 emissions, and hydrocarbon pollutants. In the recent past, several studies aimed to the development of ammonia combustion systems have been conducted. However, ammonia combustion systems face several challenges, such as poor ignition timings, lower burning velocity, low energy density, shorter flammability limits than hydrocarbons. These issues are compounded by the significant increase in NOx emissions, which makes practical application of ammonia challenging. Various conventional methods, such as blending ammonia with other hydrocarbons and hydrogen, have been employed to improve combustion performance and reduce NO x emission. Meanwhile, it increased the engine complexities and at the same time, it raised CO 2 and NO x emissions. Recently, plasma-assisted combustion (PAC) has emerged as a promising technology to boost the ammonia combustion process by improving ignition delay timings, increasing flame speed, extending flammability limits, and reducing NO x emissions. In recent years, plasma-assisted combustion (PAC) has emerged as a promising technology to enhance the ammonia combustion process by improving ignition delay timings, increasing flame speed, extending flammability limits, and reducing NOx emissions. Nevertheless, only a few studies on plasma-assisted ammonia combustion (PAAC) are available in the literature. This review paper aims to summarize the latest advancements in the field of PAAC during the last years, including progress in the development of numerical models and experimental studies. The paper highlights the detailed procedure of PAAC numerical modeling and the limitations of numerical models. Finally, the latest numerical and experimental developments of PAAC have been discussed. • Ammonia is getting more attraction as an alternative fuel for future power and transportation sectors. • A comprehensive outlook of non-thermal plasma for ammonia combustion is provided. • The in-depth mechanisms of plasma assisted combustion are highlighted. • The latest numerical and experimental studies of Plasma assisted combustion were analyzed. [ABSTRACT FROM AUTHOR]

This study introduces an innovative approach involving the injection of hydrogen into a low-swirl, non-premixed flame, which operates with gaseous fuels derived from an air-blast atomizer designed for aero-engine applications. The aim is to characterize how hydrogen enrichment influences flame structures while maintaining a constant thermal output of 4.6 kW. Using high-speed chemiluminescence imaging, three fueling conditions were compared: the first involved pure methane/air, while the second and third conditions introduced varying levels of hydrogen to an air–methane mixture. The results reveal significant effects of hydrogen enrichment on flame characteristics, including a slightly shorter length and a wider angle attributed to heightened expansion within the Combustion Recirculation Zone. Moreover, the emission of UV light underwent considerable changes, resulting in a shifted luminosity zone and reduced variance. To delve deeper into the underlying mechanisms, the researchers employed Proper Orthogonal Decomposition (POD) and Spectral Proper Orthogonal Decomposition (SPOD) analyses, showing coherent structures and energetic modes within the flames. Hydrogen enrichment led to the development of smaller structures near the nozzle exit, accompanied by longitudinal oscillations and vortex shedding phenomena. These findings contribute to an advanced understanding of hydrogen's impact on flame characteristics, thereby propelling efforts toward improved flame stability. Additionally, these insights hold significance in the exploration of hydrogen as an alternative energy source with potential environmental benefits. [ABSTRACT FROM AUTHOR]

The research effort in the microcombustor field has recently increased due to the demand for high-performance systems in microelectromechanical and micro power generation devices. To address rising concerns about pollutants from fossil sources, zero-carbon fuels such as hydrogen (H2) and ammonia (NH3) have been considered as an alternative in microcombustion processes. In a microcombustor, the surface area-to-volume ratio is much higher compared to conventional combustion systems, resulting in faster heat transfer rates and more intense combustion reactions. However, achieving efficient mixing of fuel and an oxidizer in a microcombustor can be challenging due to its small size, particularly for highly reactive fuels like H2. For NH3, challenges in microcombustion involve a low reactive, high ignition temperature (923 K vs. 793 K of H2) and high concentration of NOx combustion products. Therefore, studying the performance of these fuels in microcombustors is important for developing clean energy technologies. In this paper, to explore features of non-premixed NH3/air and H2/air combustion in micro-scale combustors, an Ansys Fluent numerical investigation was conducted on a Y-shaped microcombustor. Results show that for combustion with H2, stationary flames can be achieved even at lower equivalence ratios. Additionally, the pollutants generated from H2 in the flame are generally twice those of NH3. The overall efficiency of the microcombustor is two times greater for NH3 conditions than for H2 conditions. [ABSTRACT FROM AUTHOR]

Hereditary transthyretin amyloidosis (hATTR) is an autosomal dominant, adult-onset disease that stems from point mutations in the TTR gene encoding the protein transthyretin. The disease is progressive and life-threatening and is associated with amyloid deposits in multiple organs including the heart, kidney, skin, eyes, nervous system, and gastrointestinal tract. Genotypic and phenotypic heterogeneity is a characteristic hallmark of hereditary transthyretin amyloidosis. Herein, we present a rare variant of hATTR cardiomyopathy secondary to Ser97Tyr mutation, having been documented only in a handful of families previously. This case serves as a valuable opportunity to elucidate the clinico-pathogenesis of this disease, highlight the aggressive nature of this genetic mutation (c.290C>A; p.Ser97Tyr), and document the response to the latest advances in treatment currently available., Competing Interests: Human subjects: All authors have confirmed that this study did not involve human participants or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Yarrarapu et al.)