Publications

The title compound, 4-hydroxy-2H-1,2-benzothiazine-3-carbohydrazide 1,1-dioxide-oxalohydrazide (1:1), is determined using X-ray diffraction techniques and the molecular structure is also optimized at the B3LYP/6-31G(d,p) level using density functional theory (DFT). The asymmetric unit consists of four independent molecules. The oxalohydrazide molecules have the centre of symmetry at the mid-point of the central C-C bond. Each thiazine ring adopts a half-chair conformation. Intermolecular C-H...O, N-H...O and N-H...N hydrogen bonds produce R 2 2 (10), R 2 2 (13), R 3 3 (12) and R 3 3 (15) rings, which lead to one-dimensional polymeric chains. An extensive three-dimensional supramolecular network of N-H...N, N-H...O, C-H...O and O-H...O hydrogen bonds is responsible for crystal structure stabilization.

A series of new solid esters was synthesized by using greener chemistry strategy involving simple reaction of an alcohol with sulfonamide ligand. Characterization study of these methyl (1), ethyl (2) isopropyl (3) and n-butyl (4) ester of 4-((4-chlo-rophenylsulfonamido)methyl)cyclohexanecarboxylic acid was done by using FTIR, NMR mass spectrometry and X-ray crystallography. The compounds were optimized with Gaussian software according to basis set B3LYP/6-31G(d,p) and their different parameters related to structure were calculated. Furthermore, all compounds of the series were screened for their in vitro biological applications involving anti-bacterial (Chromohalobactor salixgens, Halomonas halofila, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Shiegella sonnei), anti-fungal (Aspergillus niger), anti-oxidant (DPPH scavenging activity) and enzyme inhibition (acetylcholine esterase and butyrylcholine esterase) study. Sulfonamide based esters were also docked against selected enzymes (AChE and BChE) using MOE software for their mode of binding. Results obtained from these biological evaluations showed that such compounds have potential against targeted activity.

Abstract Designing an electrocatalyst by integrating multiple classes of materials is an effective strategy for reinforcing the electrode properties. This study demonstrates a facile electrospinning technique for functionalizing the carbon nanofibers (CNFs) with Nb 2 O 5 co‐catalyst as the support material for platinum nanoparticles. The resultant Nb CNF‐Pt electrode has a sensible Pt loading of 30 µg cm −2 and manifests high catalytic activity towards the oxygen reduction reaction (ORR), methanol oxidation reaction (MOR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). The Nb CNF‐Pt outperforms the commercial 20 wt% Pt loaded carbon with high positive onset potential (0.99 V vs reversible hydrogen electrode (RHE)) and half‐wave potential (0.87 V vs RHE) during ORR. It also provides large electrochemical active surface area (94.19 m 2 g −1 ) and mass activity (783.34 mA mg −1 ) during MOR. Furthermore, the Nb CNF‐Pt electrode demands an extremely minimal overpotential of 37 and 325 mV and a Tafel slope of 38 and 81 mV dec −1 for HER and OER, respectively. The enhanced electrocatalytic activity of Nb CNF‐Pt is attributed to the strong metal–support interaction between Nb 2 O 5 and Pt, resulting in a uniform loading of Pt NPs with reduced particle size and agglomeration‐free distribution.

For the photocatalytic degradation of the organic dyes present in wastewater, the ternary composites of metal-oxides nanopowders of zinc-iron-calcium (Zn-Fe-Ca), zinc-iron-antimony (Zn-Fe-Sb), zinc-iron-titanium (Zn-Fe-Ti) and zinc-iron-cobalt (Zn-Fe-Co) were synthesized and characterized by different instruments. The average particle size of the Zn-Fe-Ca and Zn-Fe-Ti mixed-oxides nanopowders was 10 ± 5 nm and that of Zn-Fe-Sb nanopowder was 20 ± 10 nm. The flakes of Zn-Fe-Co nanopowder were 10 ± 5 nm thick and 100 nm to 300 nm long. All the mixed-oxides were utilized for photocatalytic degradation of acridine orange (AO) where Zn-Fe-Sb degraded the 98 % of acridine orange (AO), within 20 min, while the same level of degradation was attained by Zn-Fe-Ti and Zn-Fe-Ca mixed-oxides in 80 min and 90 min, respectively. The more efficient Zn-Fe-Sb photocatalyst was further utilized for the degradation of malachite green (MG), brilliant green (BG), methyl orange (MO) and congo red (CR). Zn-Fe-Sb was found to be fast and efficient photocatalyst for the degradation of AO and therefore, the effect of various parameters was studied in detail to optimize the reaction conditions. Moreover, the Zn-Fe-Sb mixed-oxides were used to photodegrade the AO dye in four different environmental water samples (sea, tap and sewage). Keeping in view the practical conditions, a tube-type and funnel-type filters were designed for dynamic purification process using Zn-Fe-Sb mixed-oxides as catalyst under sunlight. The synthesized nanomaterials have great potential to contribute in the wastewater treatment technologies.

In today’s world, efficiency and margin of safety are prime considerations for any applications. To address such parameters in aerospace or high-tech consumer products, there are still limitations in terms of capabilities from a material perspective. Aluminium 7075 is predominantly used as a combination material in these applications, but it has many drawbacks such as early wear/friction, low fatigue life cycle, high weight ratios, high deformation and stresses. To overcome these key issues, many reinforcements have been used to date. However, the results are not so convincing with respect to tribological applications, and the aforementioned issues still persist. In the current work, a novel hybrid composite comprising Aluminium 7075 as substrate and the reinforcement of silicon carbide and aluminium oxide at varying combinations of 3 to 9% in steps of 3% and a constant percentage of 5% were added, respectively. The exhaustive work focuses on extracting the mechanical, tribological and physical properties of a hybrid composite. Furthermore, a microcharacterisation study of these combinations was carried out using FE-SEM and EDX. In a continuation to this simulation, a study was performed using ANSYS Workbench to identify a suitable gear application with real-time loading conditions. The observed results show a tensile strength of 366 MPa for 6%SiC, hardness of 93 VHN and wear rate of 0.00025 mm3/Nm for the 9%SiC combination.

Iron oxide nanoparticles (NPs) have been prepared in large-scale by wet-chemical method (150.0 oC and pH 8.33) using ferric chloride and urea as a starting materials in aqueous-alkaline medium. The structural, physical, and optical properties are characterized using FT-IR, UV–vis spectroscopy, Raman spectroscopy, powder X-ray diffraction, Fieldemission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and Electron diffraction system (EDS). The NPs size (average dia. 45 ± 5 nm) was measured by FE-SEM while the single phase of NPs were exemplified using powder X-ray diffraction technique. As-grown nanoparticles were applied for the photocatalytic degradation using acridine orange (ACR) and chemical sensing of aqueous ammonia. Almost 58.38% degradation with ACR was observed in presence of nanoparticles under UV sources (250 W). The silver electrode (AgE, surface area, 0.0216 cm2) was immobilized with NPs which enhanced ammonia-sensing performances in their electrical response (I-V characterization) for detecting and quantifying the ammonia in aqueous system. The analytical performances of NPs sensor were investigated that the sensitivity and stability of the sensor improved extensively using NPs thin-film on active silver surface. The calibration plot was linear (R =0.9337) over the large range of 5.0 μM to 0.5 M. The sensitivity was calculated as 4.6154 μAcm-2mM-1 with detection limit (2.5±0.2 μM), based on a signal/noise ratio (3N/S). This study has introduced a novel way for efficient chemical sensor development as well as active photo-catalyst using low-dimensional NPs for the detection of environmental carcinogenic and hazardous compounds. Keywords: Iron oxide nanoparicles, Chemi-sensors, Sensitivity, Solution method, Optical properties