Hybrid CeO ₂ /Fe ₂ O ₃ composite nanospindles (CNSs) are synthesized by a simple and cost effective co-precipitation method, utilized for wastewater treatment and energy storage applications.

Incorporation of reduced graphene oxide (rGO) modifies the properties of semiconducting metal oxide nanoparticles and makes it possible to tune the surface area and pore size to optimum values, which in turn improves their gas sensing properties. In this work, to improve the ammonia (NH₃) gas sensing characteristics, reduced graphene oxide (rGO) was incorporated into tungsten oxide (WO₃) nanospheres using a simple ultrasonication method. The rGO–WO₃ nanocomposites exhibited porous nanosheets with nanospherical WO₃ as observed with field-emission scanning electron microscopy (FE-SEM). The oxidation state of the rGO–WO₃ nanocomposite was determined using X-ray photoelectron spectroscopy (XPS). Three ratios of (1, 5 and 10% rGO/WO₃) nanocomposites and pure WO₃ showed good selectivity towards NH₃ at 10–100 ppm, and more remarkably at room temperature in the range of about 32–35 °C and at a relative humidity (RH) of 55%. The limit of detection (LOD) of the synthesized rGO–WO₃ nanocomposites was 1.14 ppm, which will highly favour low detection ranges of NH₃. The sensor response was 1.5 times higher than that of the bare WO₃ nanospheres. The sensors showed excellent selectivity, ultrafast response/recovery times (18/24 s), reproducibility and stability even after one month of their preparation. We believe that metal oxides using the rGO modifier can improve the sensitivity and reduce the LOD towards NH₃ and can be used effectively in real-time environmental monitoring.

Hydroxyapatite/magnesium core–shell nanostructures were synthesized by a simple and cost effective precipitation method without a surfactant. The properties of the prepared samples were studied by using sophisticated analytical techniques. X-ray analysis confirms the phase purity and high crystallinity of the sample with an average crystallite size of 26 nm. The microscopic images show the spherical morphology of the pure and core–shell hydroxyapatite/magnesium. The other characterization studies also confirm the formation of pure hydroxyapatite and hydroxyapatite/magnesium core–shell nanostructures. The obtained materials were subjected to in vitro cell viability analysis by using human leukaemia cancer cells – K562 through a sulforhodamine-B assay. The results obtained depict that the HAp/Mg core–shell nanorods were not significantly toxic to K562 cells in the given concentrations compared with the pristine HAp. This is due to the enhanced biocompatibility and biodegradability of the magnesium shell. The present finding underlines the possible use of this material for biomedical applications.

Morphology controlled hydroxyapatite (HAp) nanostructures play a vital role in biomedical engineering, tissue regenerative medicine, biosensors, chemotherapeutic applications, environmental remediation, etc. The present work investigates the influence of temperature, pH and time on the growth of HAp nanostructures using a simple, cost effective and surfactant free chemical approach. The obtained HAp nanostructures were systematically investigated by analytical techniques such as XRD, FESEM, EDX, FTIR and Raman spectroscopy. The XRD analysis showed that the hexagonal structure of the hydroxyapatite and average crystallite size was estimated from this analysis. The electron microscopic analysis confirmed the different morphologies obtained by varying the synthesis parameters such as temperature, pH and time. The elemental composition was determined through EDS analysis. FTIR and Raman spectroscopic analysis confirmed the presence of functional groups and the purity and crystallinity of the samples. The biocompatibility and adhesion nature of samples was examined with mouse preosteoblast cells. The obtained results demonstrated good biocompatibility and excellent focal adhesion.