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Improving the safety efficacy ratio of existing drugs is a current challenge to be addressed rather than the development of novel drugs which involve much expense and time. The efficacy of drugs is affected by a number of factors such as their low aqueous solubility, unequal absorption along the gastrointestinal (GI) tract, risk of degradation in the acidic milieu of the stomach, low permeation of the drugs in the upper GI tract, systematic side effects, etc. This review aims to enlighten readers on the role of pH sensitive hydrogels in drug delivery, their mechanism of action, swelling, and drug release as a function of pH change along the GI tract. The basis for the selection of materials, their structural features, physical and chemical properties, the presence of ionic pendant groups, and the influence of their pKa and pKb values on the ionization, consequent swelling, and targeted drug release are also highlighted.

Synthesis of copper oxide (CuO) nanostructures via biological approach has gained attention to reduce the harmful effects of chemical synthesis. The CuO nanostructures were synthesized through a green approach using the Garcinia mangostana L. leaf extract and copper (II) nitrate trihydrate as a precursor at varying calcination temperatures (200–600 °C). The effect of calcination temperatures on the structural, morphological and optical properties of CuO nanostructures was studied. The red shifting of the green-synthesized CuO nanoparticles’ absorption peak was observed in UV-visible spectrum, and the optical energy bandgap was found to decrease from 3.41 eV to 3.19 eV as the calcination temperatures increased. The PL analysis shown that synthesized CuO NPs calcinated at 500 °C has the maximum charge carriers separation. A peak located at 504–536 cm−1 was shown in FTIR spectrum that indicated the presence of a copper-oxygen vibration band and become sharper and more intense when increasing the calcination temperature. The XRD studies revealed that the CuO nanoparticles’ crystalline size was found to increase from 12.78 nm to 28.17 nm, and dislocation density decreased from 61.26 × 1014 cm−1 to 12.60 × 1014 cm−1, while micro strain decreased from 3.40 × 10−4 to 1.26 × 10–4. From the XPS measurement, only CuO single phase without impurities was detected for the green-mediated NPs calcinated at 500 °C. The morphologies of CuO nanostructures were examined using FESEM and became more spherical in shape at elevated calcination temperature. More or less spherical nanostructure of green-mediated CuO calcinated at 500 °C were also observed using TEM. The purity of the green-synthesized CuO nanoparticles was evaluated by EDX analysis, and results showed that increasing calcination temperature increases the purity of CuO nanoparticles.

In this study, phytochemical assisted nanoparticle synthesis was performed using Muntingia calabura leaf extracts to produce copper oxide nanoparticles (CuO NPs) with interesting morphology. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis of the biosynthesized CuO NPs reveal formation of distinct, homogeneous, and uniform sized CuO nanorods structure with thickness and length of around 23 nm and 79 nm, respectively. Based on Fourier-transform infrared (FTIR) analysis, the unique combinations of secondary metabolites such as flavonoid and polyphenols in the plant extract are deduced to be effective capping agents to produce nanoparticles with unique morphologies similar to conventional chemical synthesis. X-ray diffraction (XRD) analysis verified the monoclinical, crystalline structure of the CuO NPs. The phase purity and chemical identity of the product was consolidated via X-Ray photoelectron spectroscopy (XPS) and Raman spectroscopic data which indicate the formation of a single phase CuO without the presence of other impurities. The direct and indirect optical band gap energies of the CuO nanorods were recorded to be 3.65 eV and 1.42 eV.

Metal halide perovskites are regarded as promising photovoltaic candidates in the solar industry due to their high photon-to-current conversion efficiency, outstanding processability, chemical characteristics, and cost-effectiveness. However, their stability is a major concern for large-scale applications. Recently, potential-induced performance degradation (PID) has arisen as a prevalent risk that affects the lifetime of photovoltaics resulting from negative bias and adverse environmental conditions. Throughout this study, the influence of PID on four perovskite (MAPbI3, CsPbI3, CsGeI3, and CsSnI3) device structures is demonstrated, and the device performance is evaluated using SCAPS-1D. Intrinsic defects of different scales in the absorber layer are incorporated to trigger the PID effect, and its impact on different PSCs is examined. Additionally, quantum efficiency and impact on band energy are also investigated. The results reveal that the CsPbI3-based solar cell has the highest defect tolerance limit of 1 × 1017 cm−3. The study further reveals that under PID, FTO/TiO2/CsPbI3/NiO/Au shows better stability than other structures, with power conversion efficiency of 18.13%.

Starch and cellulose have long been used in various industrial applications as gelating agents. In this work, the intrinsic adhesive properties of these biopolymers are exploited for application as electrolytes in DSSC. Firstly, potato starch was chemically modified into phthaloyl starch in a facile esterification process. Fabrication of polymer electrolyte with phthaloyl starch (PhSt) and hydroxyethyl cellulose (HEC) incorporated with dimethylformamide and tetrapropylammonium iodide produced homogeneous gels with diminished crystallinity. Infusion of different weight percentages of 1-butyl-3-methylimidazolium iodide (BMII) into the gels were revealed to further suppress polymer crystallinity and elevate ionic conductivity. Rheological analysis revealed that addition of up to 6 wt% of ionic liquid aid in elevating the rigidity, strength and tackiness of the gels. The improved adhesiveness of the gels can be correlated to effective reduction of interfacial resistance and restraining of recombination reactions based on electrochemical impedance spectroscopy. Quasi-solid DSSC fabricated with PhSt-HEC with 8 wt% of BMII exhibited enhanced short-circuit current density, JSC and fill factor, contributing to an optimized efficiency of 5.20%. Graphic abstract

A starch-resorcinol-formaldehyde (RF)-lithium triflate (LiTf) based biodegradable polymer electrolyte membrane was synthesized via the solution casting technique. The formation of RF crosslinks in the starch matrix was found to repress the starch’s crystallinity as indicated by the XRD data. Incorporation of the RF plasticizer improved the conductivity greatly, with the highest room-temperature conductivity recorded being 4.29 × 10−4 S cm−1 achieved by the starch:LiTf:RF (20 wt.%:20 wt.%:60 wt.%) composition. The enhancement in ionic conductivity was an implication of the increase in the polymeric amorphous region concurrent with the suppression of the starch’s crystallinity. Chemical complexation between the plasticizer, starch, and lithium salt components in the electrolyte was confirmed by FTIR spectra.

Tungsten oxide (WOx) thin films were synthesized through the RF magnetron sputtering method by varying the sputtering power from 30 W to 80 W. Different investigations have been conducted to evaluate the variation in different morphological, optical, and dielectric properties with the sputtering power and prove the possibility of using WOx in optoelectronic applications. An Energy Dispersive X-ray (EDX), stylus profilometer, and atomic force microscope (AFM) have been used to investigate the dependency of morphological properties on sputtering power. Transmittance, absorbance, and reflectance of the films, investigated by Ultraviolet-Visible (UV-Vis) spectroscopy, have allowed for further determination of some necessary parameters, such as absorption coefficient, penetration depth, optical band energy gap, refractive index, extinction coefficient, dielectric parameters, a few types of loss parameters, etc. Variations in these parameters with the incident light spectrum have been closely analyzed. Some important parameters such as transmittance (above 80%), optical band energy gap (~3.7 eV), and refractive index (~2) ensure that as-grown WOx films can be used in some optoelectronic applications, mainly in photovoltaic research. Furthermore, strong dependencies of all evaluated parameters on the sputtering power were found, which are to be of great use for developing the films with the required properties.

Cellulose is widely appreciated amongst polymer scientists as the most abundant and cost-effective natural polysaccharide. Nonetheless, the non-dissolving property of cellulose has narrowed its potential from a broader range of applications. Hence, modification has to be made in order to improve its solubility. In this study, a simple, robust and rapid transesterification method using vinyl acetate was carried out by acetylating microcrystalline cellulose (MCC) to obtain cellulose acetate (CA). The solubility test showed an improvement of organosolubility for the modified cellulose. Series of CA powders at five different degrees of substitution (DS) were prepared by varying the composition of cellulose to vinyl acetate molar ratios. Successful acetylation of cellulose was confirmed through Fourier transform infrared (FTIR) and proton nuclear magnetic resonance ( 1 H NMR) spectroscopies. Physicochemical traits were studied by using X-ray diffraction (XRD) and thermogravimetric analysis (TGA). XRD and TGA measurements revealed that CA powders of different DS were less crystalline and more thermally stable than its native form. The CA powders were turned into quasi-solid polymer electrolytes (PEs) and the highest ionic conductivity reported in this study was 7.31 × 10 −3  S cm −1 with incorporation of 20 wt.% sodium iodide (NaI) salt. Rheology study was carried out to investigate the mechanical strength of the gels. Quasi-solid PEs were prepared for potential dye-sensitized solar cells (DSSCs) application.

Generation of energy across the world is today reliant majorly on fossil fuels. The burning of these fuels is growing in line with the increase in the demand for energy globally. Consequently, climate change, air contamination, and energy security issues are rising as well. An efficient alternative to this grave hazard is the speedy substitution of fossil fuel-based carbon energy sources with the shift to clean sources of renewable energy that cause zero emissions. This needs to happen in conjunction with the continuing increase in the overall consumption of energy worldwide. Many resources of renewable energy are available. These include thermal, solar photovoltaic, biomass and wind, tidal energy, hydropower, and geothermal. Notably, tidal energy exhibits great potential with regard to its dependability, superior energy density, certainty, and durability. The energy mined from the tides on the basis of steady and anticipated vertical movements of the water, causing tidal currents, could be converted into kinetic energy to produce electricity. Tidal barrages could channel mechanical energy, while tidewater river turbines can seize the energy from tidal currents. This study discusses the present trends, ecological effects, and the prospects for technology related to tidal energy.

Bifunctional electrocatalysts are in demand to pursue dual functions in applications like energy conversion and pollution treatment. In this study, we synthesize the iron-copper-nickel sulfide (FeCuNiS) catalysts with partial amorphous character via the hydrothermal method. The iron rich composition with optimal copper and nickel ratios exhibits robust performances on hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions. The partial amorphous feature offers more active sites for reaction due to the partial disordered structure. The partially amorphous FeCuNiS exhibits lower overpotential for HER and OER at 50 mAcm . Moreover, all compositions were found to be electrocatalytically stable. The optimum design and synthesis strategy of the partially amorphous bifunctional electrocatalysts provided in this work will open pathways to advanced electrocatalysts for energy conversion applications.