Microstructural characterization of medical-grade stainless steel powders prepared by mechanical alloying and subsequent annealing

The harmful effect of nickel ions released from conventional stainless steel implants has provided a high level of motivation for the further development of nickel-free stainless steels. In this paper, the microstructure of medical-grade nickel-free stainless steel powders, with the chemical composition of ASTM F2581, is studied during mechanical alloying and subsequent annealing. Rietveld X-ray diffraction and transmission electron microscopy evaluations reflect nanocrystallization, austenitization and amorphization of the powders due to mechanical activation. It is also realized that annealing of the as-milled powder can develop a single austenitic structure with nanometric crystallite sizes, implying a considerable inherent resistance to grain growth. This study demonstrates the merit of mechanical alloying and subsequent annealing in the development of nanostructured medical-grade stainless steels. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved

Effects of chemical and mechanical funtionalization of carbon nanotubes on the behavior of a CNT/Phenolic nanocomposite

Carbon nanotubes and their treatments play an important role in fabrication and properties of the nanocomposites. In this study effects of acid functionalization and mechanical treatment of CNTs by ball milling on the chemical structure, weight loss and mechanical strength of a 1 weight % CNTs reinforced phenolic polymer has been investigated by using FTIR, XRD, TGA, electron microscopy and tensile tests. Results show that both chemical and mechanical treatment has considerable effects on properties of the composite. Maximum strength was obtained by chemical treatment followed by 2 hours of mechanical treatment, further milling treatment caused to decrease the strength of the composit

Hemiplegia and Facial Palsy due to Brucellosis

AbstractManifestations involving the nervous system (neurobrucellosis), is a treatable infection, however it is not well documented. Direct invasion of the central nervous system occurs in fewer than 5% of cases. Acute or chronic meningitis is the most frequent nervous system complication. However, hemiplegia and cranial nerve involvement are rarely encountered. In this report we present a patient with “seventh cranial nerve palsy” and “hemiplegia,” as the manifestations of probable neurobrucellosis.Thus, in endemic area, brucellosis should be ruled out in patients who develop unexplained neurological symptoms such as hemipleg

Facile synthesis and electrochemical performance of graphene-modified cu2o nanocomposite for use in enzyme-free glucose biosensor

Graphene-modified Cu2O nanocomposite was synthesized under a facile microwave irradiation of an aqueous solution and has been investigated as an enzyme-free glucose biosensor. Morphology and crystal structure of the graphene-modified Cu2O nanocomposite were investigated by using electron microscopy and X-Ray Diffraction (XRD) analyses. Also, the electrochemical performance of the graphene-modified Cu2O nanocomposite for the measurement of glucose concentration in alkaline media was evaluated by using cyclic voltammetry and chronoamperometric measurements. The electrochemical studies revealed that graphene-modified nanocomposite electrode exhibited a high performance for non-enzymatic oxidation of glucose with a desirable sensitivity. Also, the fabricated graphene-modified biosensor exhibited a wide linear response for glucose detection in the concentrations ranges from 2 µM to 12 mM and a desirable detection limit of 2 µM. In addition, the graphene-modified Cu2O nanocomposite provided an appropriate selective response for glucose detection in presence of high concentrations of ascorbic acid and dopamine. © 2020, Iranian Institute of Research and Development in Chemical Industries. All rights reserved.1

The effect of particle size and volume fraction on the aging behavior of a liquid-phase sintered SiC/aluminum composite

The aging response of a SiC particulate reinforced powder metallurgy aluminum composite was examined as a function of particle size and volume fraction. The addition of SiC particles ranging in size from 24 to 142 μm at 9 vol pct had no effect on the aging kinetics of the composites. Acceleration of the aging behavior or inhibition of the initial stage of the age-hardening process was observed at 18 and 27 vol pct. The accelerated aging kinetics were consistent with smaller particles creating larger thermal misfit dislocation densities. In addition, it was shown that different combinations of ceramic particle size and volume fraction lead to similar effects on the aging behavior. Loss of the initial hardening response was attributed to the suppression of Guinier-Preston (GP) zone formation due to the annihilation of excess vacancies at the thermal misfit dislocations. © 1995 The Minerals, Metals & Material Society