Effect of rare earth dopants on structural and mechanical properties of nanoceria synthesized by combustion method

Structural characteristics of combustion synthesized, calcined and densified pure and doped nanoceria with tri-valent cations of Er, Y, Gd, Sm and Nd were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The results showed that the as-synthesized and calcined nanopowders were mesoporous and calculated lattice parameters were close to theoretical ion-packing model. The effect of dopants on elastic modulus, microhardness and fracture toughness of sintered pure and doped ceria were investigated. It was observed that tri-valent cation dopants increased the hardness of the ceria, whereas the fracture toughness and elastic modulus were decreased

Structural and mechanical properties of La0.6Sr0.4M0.1Fe0.9O3-δ (M: Co, Ni and Cu) perovskites

La0.6Sr0.4M0.1Fe0.9O3-δ (M: Co, Ni and Cu) perovskite nanostructures were synthesized using low frequency ultrasound assisted synthesis technique and effect of substitution of Fe by Co, Ni and Cu on crystal structure and mechanical properties in La0.6Sr0.4FeO3-δ perovskite were studied. The HRTEM and Rietveld refinement analyses revealed the uniform equi-axial shape of the obtained nanostructures with the existence of La0.6Sr0.4M0.1Fe0.9O3−δ with mixed rhombohedral and orthorhombic structures. Substitution of Cu decreases the melting point of La0.6Sr0.4FeO3-δ. The results of mechanical characterizations show that La0.6Sr0.4Co0.1Fe0.9O3−δ and La0.6Sr0.4Ni0.1Fe0.9O3−δ have ferroelastic behavior and comparable elastic moduli, however, subtitution of Ni shows higher hardness and lower fracture toughness than Co in Bsite dopin

The Role of a Multi-Step Core Stability Exercise Program in the Treatment of Nurses with Chronic Low Back Pain: A Single-Blinded Randomized Controlled Trial

Study Design Single-blinded randomized controlled trial. Purpose To evaluate the effects of a multi-step core stability exercise program in nurses with chronic low back pain (CLBP). Overview of Literature CLBP is a common disorder among nurses. Considering that patient-handling activities predispose nurses to CLBP, core stability exercises suggested for managing CLBP in the general population may also be helpful in nurses. However, sufficient evidence is not available on whether a multi-step core stability exercise program affects pain, disability, quality of life, and the diameter of lateral abdominal muscles in nurses with CLBP. Methods In this single-blinded randomized controlled trial, 36 female nurses with CLBP were recruited. The sample was divided into two groups of 18 patients (intervention and control). Nurses in the intervention group performed core stability exercises for 8 weeks, based on a progressive pattern over time. Roland–Morris Disability Questionnaire (RDQ), quality of life (36-item Short Form Health Survey [SF-36]), ultrasound assessment of the diameter of lateral abdominal muscles, and Visual Analog Scale (VAS) score for pain were evaluated in the participants before and after the trial. Sixteen nurses (eight from each group) dropped out of the study, and analysis of covariance was used to compare outcomes for the remaining nurses in the intervention (10 nurses) and control (10 nurses) groups. Results The results after the trial showed significant improvements in RDQ, SF-36, and VAS score in the intervention group compared with that in the control group (p <0.005). Furthermore, the ultrasound data showed a significant increase in the left and right muscle diameter of all three abdominal muscles during the abdominal drawing-in maneuver in the intervention group compared with that in the control group (p <0.05). Conclusions This study showed that a multi-step core stability exercise program is a helpful treatment option for improving quality of life and reducing disability and pain in female nurses with CLBP

Preparation of nanosized yttrium doped CeO2 catalyst used for photocatalytic application

In the present work, the pure CeO2 and yttrium doped CeO2 nanopowders were synthesized by the nitrate-fuel self-sustaining combustion method and calcined at 700 C for 2 h. X-ray diffraction (XRD) and high resolution electron transmission microscopy (HRTEM) results demonstrated a cubic fluorite with high purity and the crystallite sizes less than 20 nm calculated from Scherrer’s formula. The BET specific surface area of yttrium doped CeO2 samples showed high values than those of pure CeO2. The photocatalytic activity of yttrium doped CeO2 showed high degradation of Rhodamine B solution under visible light illumination

Room Temperature Ferroelastic Creep Behavior of Porous (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ

The time-dependent deformation of porous (La0.6Sr0.4)0.95Co0.2Fe0.8O3-&delta; (LSCF) under constant uniaxial compressive stress at room temperature has been studied. Both axial and lateral stress&ndash;strain deformation curves clearly show the non-linear ferroelastic behavior of LSCF perovskite during compression. The ferroelastic characteristics of deformation curves such as coercive stress and apparent loading moduli decrease when the porosity of the samples increases. Ferroelastic creep deformations at applied stresses of 25 and 50 MPa demonstrate that stress and porosity are influencing factors on creep deformation, which increases with increasing stress and porosity. A negative creep or axial expansion and lateral contraction were observed in the sample with 35% porosity under 50-MPa constant compression stress

Ferroelastic behavior of LaCoO3: A comparison of impression and compression techniques

Ferroelastic mechanical behavior of LaCoO3 was investigated by the impression test and compared with the conventional compression test using digital image correlation technique for deformation measurement. The results show that the coercive stress for ferroelastic deformation can be detected by impression test, which is less than critical stress for such deformation in the compression test. Room temperature ferroelastic impression creep characterization showed different equilibrium penetration of flat-end punch at different constant stresses, which can be characterized by Prony series equation

Optical, vibrational and fluorescence recombination pathway properties of nano SiO2-PVA composite films

We report optical and spectroscopic investigations on polyvinyl alcohol (PVA)/silica composite free standing films. Amorphous silica nanoparticles are synthesized from rice husk ash using pyrolysis technique. PVA/silica nano composite free standing films are prepared by simple chemical method. As prepared nano composites are characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, photoluminescence spectroscopy (PL) and time resolved photoluminescence (TRPL) spectroscopy techniques. Spectroscopic studies reveal the structural modification of silica nanoparticle in PVA matrix due to the formation some new chemical bonds. The prepared PVA/Silica composites exhibit exceptional optical properties which can be applicable for Opto-electronic device applications

Chitosan-pluronic based Cu nanocomposite hydrogels for prototype antimicrobial applications

Copper nanoparticles were synthesized via precipitation technique using the pseudonatural cationic chitosan biopolymer as a stabilizing agent. The nanoparticles developed were successfully incorporated into the 1:1 ratio of blended chitosan: pluronic F127 polymer solution and made their nanocomposite hydrogels by solution casting method. The formed copper-based nanocomposite hydrogels were characterized by using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy and transmission electron microscopy studies. The antimicrobial activity of the fabricated nanocomposite hydrogels was tested via an inhibition zone process against both E. coli (gram-negative) and S. aureus (gram-positive) bacteria. The results conveyed that the copper-embedded chitosan-pluronic\ F127 nanocomposite hydrogels can be used effectively for antimicrobial applications as well as for wound care applications.Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT), CONICYT FONDECYT: 3170272, 11160073 Universidad de Talca, Talca, Chile Proyecto de Investigacion enlace FONDECYT Universidad de Talca: 300061 CIPA, CONICYT Regional, GORE BIO-BIO: R17A1000