Podcasting as an Effective Pedagogy for Teaching Chemistry During the COVID-19 Pandemic and Beyond

The COVID-19 pandemic has forced all educational institutions worldwide to switch their active routine to ONLINE. With students attending classes virtually, a number of problems arose including the absence of social interaction and the imposed difficulty of digesting the materials of different courses, especially for those with a scientific background. General chemistry (GC), as an introductory course, is usually registered by students from different backgrounds, including Science, Engineering, and Agriculture. At the United Arab Emirates University, the second level of GC (GCII) is more focused on problem-solving as related to various topics. With the absence of face-to-face experience because of the COVID-19 circumstances, students’ understanding of the chemical concepts and implementing that in problem-solving has become a challenge. The current work investigates the effect of using professionally-made podcasts of GCII on the extent of understanding of students registered for this course during the period of 2020-2020 over a course of four semesters. The results of surveying the usage and feedback of students engaged in this experiment are outlined. Conclusively, this pedagogy is fully supported by most of the students who regard it as a suitable alternative to face-to-face settings

Biodegradable Scaffolds for Gastric Tissue Regeneration

Tissue engineering has been viewed as a valid approach toward the partial or total replacement of defective tissues and organs. Recent advances in nanotechnology have made it possible to develop biocompatible materials at the micro- and nano-scales to be used as scaffolds for cellular growth and regeneration of defective tissues. Gastric mucosal lining is an example of soft tissues that are highly susceptible to damage due to various reasons including cancer or ulcer development. Current therapeutic approaches to these diseases have some limitations. This chapter describes the basis for development of a novel modality combining nanotechnology, stem cells, and tissue engineering for the replacement of defective gastric tissues using synthetic biocompatible scaffolds. These microfibrous scaffolds are seeded with gastric stem cells, which are studied for their proliferation and differentiation into functional gastric mucous cells

Preparation, Structural Characterization, and Biomedical Applications of Gypsum-Based Nanocomposite Bone Cements

Hard tissues are natural nanocomposites comprising collagen nanofibers that are interlocked with hydroxyapatite (HAp) nanocrystallites. This mechanical interlocking at the nanoscale provides the unique properties of hard tissues (bone and teeth). Upon fracture, cements are usually used for treatment of simple fractures or as an adhesive for the treatment of complicated fractures that require the use of metallic implants. Most of the commercially available bone cements are polymer-based, and lack the required bioactivity for a successful cementation. Besides calcium phosphate cements, gypsum is one of the early recognized and used biomaterials as a basi for a self-setting cementation. It is based on the controlled hydration of plaster of Paris at room temperature and its subsequent conversion to a self-setting solid gypsum product. In our work, we have taken this process further towards the development of a set of nanocomposites that have enhanced bioactivity and mechanical properties. This chapter will outline the formation, characterization, and properties of gypsum-based nanocomposites for bone cement applications. These modified cements can be formulated at room temperature and have been shown to possess a high degree of bioactivity, and are considered potential candidates for bone fracture and defect treatment

Fabrication and characterization of cellulose acetate-based nanofibers and nanofilms for H2S gas sensing application

Electrospun nanofibers and solution-casting nanofilms were produced from an environmentally friendly cellulose acetate (CA) blended with glycerol (as an ionic liquid (IL)), mixed with polypyrrole (PPy, a conducting polymer) and doped with tungsten oxide (WO3) nanoparticles. The sensing membranes fabricated were used to detect H2S gas at room temperature and shown to exhibit high performance. The results revealed that the lowest operating temperature of both nanofiber and nanofilm sensors was 20oC, with a minimum gas detection limit of 1 ppm. Moreover, the sensor exhibits a reasonably fast response, with a minimum average response time of 22.8 and 31.7 s for the proposed nanofiber and nanofilm based sensors, respectively. Furthermore, the results obtained indicated an excellent reproducibility, long-term stability, and low humidity dependence. Such distinctive properties coupled with an easy fabrication technique provide a promising potential to achieve a precise monitoring of harmful H2S gas in both indoor and outdoor atmospheres

Enhancing Learning Experience of General Chemistry Using Pre-designed Podcasts and Flipped Classroom Methodology

Introductory courses such as General Chemistry I, General Physics General Biology and I need special attention as students taking these courses are usually in their first year of the university. In addition to the language barrier for most of them, they also face other difficulties if these elementary courses are taught traditionally. Changing the routine method of teaching of these courses is therefore mandated. In this regard, podcasting of chemistry lectures was used as an add-on to the traditional and non-traditional methods of teaching chemistry to science and non-science students. Podcasts refer to video files that are distributed in a digital format through the Internet using personal computers or mobile devices. The pedagogical strategy is another way of identifying podcasts. Three distinct teaching approaches are evident in the current literature and include receptive viewing, problem-solving, and created video podcasts. Originally, podcasting was the name given to audio files played on Apple’s iPod portable media player. The digital format and dispensing of video podcasts have stabilized over the past eight years, the type of podcasts vary considerably according to their purpose, the degree of segmentation, pedagogical strategy, and academic focus. In this regard, the whole syllabus of “General Chemistry I” course was developed as podcasts, which were delivered to students throughout thesemester. Students used the podcasted files extensively during their studies, especially as part of their preparations for exams. Feedback of students strongly supported the idea of using podcasting as it reflected its effect on the overall understanding of the subject and a consequent improvement of their grades

Enhancing the Stability of Cu‐BTC Metal‐Organic Framework via the Formation of Cu‐BTC@Cu3(PO4)2 MOF Core‐Shell Nanoflower Hierarchical Hybrid Composites

Abstract Hybrid organic‐inorganic nanoflowers (NFs) have recently emerged as a critical tool in enhancing the stability and activity of biomolecules due to their expansive surface area and porosity. The delicate petal‐like features of NFs offer innumerable sites for biomolecule adsorption, including but not limited to proteins, amino acids, and enzymes. Cu‐BTC, a copper‐based Metal‐Organic Framework (MOF) has been hindered in its potential for diverse applications by its instability in humid and aqueous conditions. To overcome this limitation, this study explores the stabilization of Cu‐BTC via the mineralization of its surface with the formation of copper phosphate nanoflowers (NFs). To initiate the mineralization process and provide a template for the growth of the NFs, a physiologically rich amino acid medium is employed. The inclusion of amino acids in the RPMI medium played a crucial role in the preservation of the Cu‐BTC hierarchical structure by facilitating the self‐assembly of copper phosphate nanoflowers on its surface, thereby producing a Cu‐BTC@Cu3(PO4)2 core‐shell structure. The innovative mechanism behind the formation of copper phosphate nanoflowers in this study and its consequential stabilization of the Cu‐BTC MOF structure underscore its novel nature

Electrospun Polystyrene/LDH Fibrous Membranes for the Removal of Cd2+ Ions

Layered double hydroxides (LDHs) have been extensively studied for a broad range of applications because of their ease of synthesis and chemical modifications. The chemical and crystal structure of LDH provides opportunities of combination with polymers forming nanocomposites. In the current study, MgAl-LDH particulates have been incorporated into micro- and nanofibers of polystyrene (PS) using an electrospinning processing technique of their respective homogeneous solutions. The effect of the varying proportions of LDH and PS on the structure, morphology, and thermal properties of the fabricated LDH-PS fibrous membranes has been investigated. The potential application of the optimally fabricated LDH-PS fibrous membranes in the removal of Cd2+ ions from aqueous media has been evaluated as well. Results showed the possibility of loading the PS fibrous membranes with up to 60 wt% of LDH particulates, which in turn modified the thermal stability and integrity of the produced fibrous membranes. Due to the high hydrophobicity of the PS fibrous matrix, no changes in the crystal structure of the LDH inclusions were observed. Both as-prepared LDH particulates and optimally prepared LDH-PS fibrous membranes showed a high potential for the removal of Cd2+ ions from aqueous media. This is attributed to a cation-exchange mechanism involving the adsorption of Cd2+ ions from a solution with the preferential leakage of Al3+ ions from the crystal structure of LDH

Polyethylene and Polyvinyl Chloride-Blended Polystyrene Nanofibrous Sorbents and Their Application in the Removal of Various Oil Spills

Polymers provide a wide range of properties, and these properties can be greatly enhanced and modified through polymer blending. Polymer blending combines the properties and advantages of their original polymers. This paper showcases hydrophobic polymers prepared through polymer blending; these blends are characterized and evaluated for their efficiency in the removal of crude oil spills from aqueous media. The application of these blends holds a great deal of importance in preserving the environment and the recovery of lost oil in spills. The blends are produced using polystyrene (PS) as the matrix polymer and individually blending poly(vinyl chloride) (PVC) and polyethylene (PE) with the PS consisting of proportions of 5–20 wt.% each. The blends are then electrospun into bead-free microfibers with interconnected porosities as shown by their respective scanned electron micrographs. All fibrous sorbents showed a high affinity towards the removal of crude oil, motor oil, and diesel spills. The highly viscous motor spill showed a different pattern of sorption onto fibers than that of crude oil and diesel spills. Upon comparing all the studied electrospun fibers to commercially available polypropylene fibrous sorbents, results show that the sorption efficiency of the electrospun fibers is superior. Most notably, both PS-PE5 and PS-PVC5 fibers showed to be highly more effective than commercially available polypropylene (PP) sorbents towards all types of oil spills

Structural evaluation, preliminary in vitro stability and electrochemical behavior of apatite coatings on Ti6Al4V substrates

Medical-grade alloys, such as Ti-6Al-4V, have been used for fixation of fractured bone and for the total replacement of defective bone. Their bioactivity could be improved by applying a bone-like apatite layer onto their surfaces. This, in turn, enhances their integration with the surrounding tissues upon implantation. In addition, the presence of a bioactive bone-like coating minimizes the likelihood of corrosion. Various methods are known for the formation of apatite coating onto Ti-6Al-4V, among which sputtering has shown its promise as a simple direct method. In the current work, a sputtering technique was used to develop a 300�nm-thick bone-like apatite layer onto Ti-6Al-4V. Structural composition, integrity and morphology of the as-coated and thermally treated coatings were investigated. Coated substrates were further evaluated after soaking them in a simulated body fluid (SBF) for up to 14 days. Results showed the formation of an amorphous apatite layer onto the alloy, that was further shown to partially crystallize upon heat treatment. As a result of SBF treatment, the apatite layer was found to remodel through a dissolution-precipitation mechanism due to its amorphous and non-stoichiometric nature, forming a smooth layer with better homogeneity and decreased surface roughness. Electrochemical analysis of the coated alloys showed the enhanced corrosion protection of the alloy surfaces by coating them with apatite. In addition, pre-grinding of the alloy surfaces before the formation of the coating was also found to improve the corrosion inhibition of the alloy surfaces in aqueous media.The authors deeply acknowledge the funding received from the College of Science at the UAE University Fund FIRP2009 to carry out the above-mentioned experiments. The authors also acknowledge Khalifa University Internal Research Fund 210103 for sponsoring the XPS and SEM analysis of the coatings.Scopu

Surface modification of HKUST-1 for enhanced activity of immobilized formate dehydrogenase used in CO2 hydrogenation

Post synthetic modification of a hydrophilic metal–organic framework (MOF), HKUST-1, with stearic acid (SA) was carried out to enhance the stability of HKUST-1 in aqueous solution to be used as a support for formate dehydrogenase (FDH) used for CO2 conversion to formate. SA modification improved the hydrophobicity without affecting the morphology and crystal structure of MOF. Adsorption of FDH on the modified MOF (SA@HKUST-1) was compared to that of the native HKUST-1 and ZIF-L. The adsorption kinetics on all MOFs was found to follow pseudo-second order kinetics and the isotherm was best described by Freundlich model. The high stability of SA@HKUST-1 and enhanced hydrophobic interaction between support and CO2 resulted in high catalytic efficiency and stability of FDH@SA@HKUST-1. The immobilized enzyme retained 95.1% of its initial activity after 4 cycles of repeated use. It was also shown that FDH@SA@HKUST-1 retained morphology and crystal structure after repeated use. Results of the present work provide novel insight into the influence of hydrophobic MOFs on the activity and stability of immobilized FDH. These findings are expected to assist in developing highly active and stable biocatalysts for CO2 hydrogenation at commercial level