Effect of Intermittent Overload Cycles on Thermomechanical Fatigue Life of NiTi Shape Memory Alloy Wire

Effect of intermittent overload cycles on fatigue behavior of NiTi shape memory alloy wire during thermomechanical cycling (TMC) has been evaluated. Results showed that fatigue life of NiTi is enhanced when the intermittent overload is above certain minimum level. An enhancement in fatigue life by ~50 pct is observed when the overload ratio is 2.0. Accumulation of plastic strain in the material under such TMC condition is found to be relatively high compared to that of TMC with no overload cycles.     

Facile one‐pot hydrothermal synthesis of stable and biocompatible fluorescent carbon dots from lemon grass herb

Luminescent carbon‐based nanomaterials hold great promise due to their stable photo‐physical behaviour, biocompatibility and lower toxicity. This work involves economic and facile one‐pot green synthesis of water‐soluble nanostructures from lemon grass (LGNS) [Cymbopogon citratus (DC) Stapf] as carbon source. High‐resolution transmission electron microscopy confirmed the formation of LGNS with lattice spacing of 0.23 nm matching low‐dimensional graphitic structures. The strong absorption exhibited at 278 nm could be attributed to л‐states of sp² /sp³ hybridisation in carbon nanostructures. Fluorescence spectroscopy of LGNS exhibited strong excitation‐dependent emission properties over a broad range of wavelengths from 300 to 600 nm. Quantitatively, these LGNS were estimated to have quantum yield of 23.3%. Biomass derived LGNS could be potentially exploited for wide variety of applications like bioimaging, up‐conversion, drug delivery and optoelectronic devices. To this extent, synthesised LGNS were used to image yeast cells via multicolour/multi‐excitation fluorescence imaging.Inspec keywords: fluorescence, carbon, nanofabrication, photoluminescence, toxicology, transmission electron microscopy, cellular biophysics, biomedical optical imaging, nanomedicine, biomedical materials, microorganisms, liquid phase depositionOther keywords: one‐pot hydrothermal synthesis, biocompatible fluorescent carbon dots, lemon grass herb, luminescent carbon‐based nanomaterials, stable photophysical behaviour, toxicity, water‐soluble nanostructures, carbon source, high‐resolution transmission electron microscopy, low‐dimensional graphitic structures, hybridisation, carbon nanostructures, fluorescence spectroscopy, excitation‐dependent emission properties, biomass derived LGNS, bioimaging, drug delivery, optoelectronic devices, yeast cell image, multicolour‐multiexcitation fluorescence imaging, C     

On stability of NiTi wire during thermo-mechanical cycling

The use of NiTi wire as thermal actuator involves repeated thermal cycling through the transformation range under a constant or fluctuating load. The stability of the material under such conditions has been a concern for the past many years. Experimental results show that for a given alloy composition, the repetitive functional behaviour of NiTi wire is largely dependent on the processing schedule/parameters and the stress-strain regime of thermo-mechanical cycling (TMC). Among the various processing parameters, retained cold work in the material and the shape memory annealing temperature/time have significant influence. It has been shown in the present study that for a stable functional behaviour, the material needs to be tailored through judicious selection of these parameters. Study also shows that, after processing, the material requires an additional stabilization treatment for ensuring minimal variation in the repetitive functional response upon TMC.     

Enhanced dissolution characteristics of piroxicam–Soluplus® nanosuspensions

In the present study, we have prepared nanosuspensions of piroxicam using Soluplus® as the matrix using aqueous-based conventional ball milling. The comparative physico-chemical characteristics were assessed using PXRD (powder X-ray diffraction), DSC (differential scanning calorimetry), FESEM (field emission scanning electron microscopy) and FTIR (Fourier transform infrared spectroscopy) analysis, indicating the nanoformulations displayed lower crystallinity with no chemical interactions between the drug and polymer molecules. The cytotoxicity of the formulations was established from MTT assay performed on Caco-2 cell lines. The release rate of piroxicam from various ratios of drug/polymer nanoparticles was investigated using a USP paddle apparatus. The nanoformulations exhibited higher release of the drug in comparison with the pure drug. The enhanced dissolution characteristics of the drug in the nanoformulations could possibly increase the anti-inflammatory effects of the drug owing to superior bioavailability characteristics.