Papers by Keyword: In Situ Analysis

Abstract: A new automated smartphone-based assay for metals ions determination based on the color reaction with organic ligands was developed. Quantification was performed by measuring the color of the polymer optode. This offers a smartphone-based alternative to the colorimeric method for signal treatment usually employed in automatic methods. The technique enabled linear calibration within the range 1–500 ppb of metals ions. The sampling time used for this concentration range was 15 min. The method was also tested for the quantification of metals ions in water samples, followed by digital image treatment of the optode. The automated detection metals ions approach was demonstrated by applying smartphone to the analysis of metals ions. Relative recoveries of the analytes ranged from 87 % to 105 %. The described procedure has the potential to be a fully automated online smartphone platform for the purpose of routine onsite water analysis.

Abstract: The visible sensing determination with color change after solid phase extraction using polymethacrylate matrix and colorimetric smartphone-based technique have been highlighted. The smartphone-based method based on digital photo of transparent polymer optode for metal ions determination is proposed for diapason 0.02-60 mg/L. The optical property of polymer matrix enables a visual color change during its reaction with the analytes. Proposed method is compared with spectrophotometric and colorimetric analysis.

Abstract: This article presents as follows the most recent progresses of our group on in-situ characterization and evaluation of the molecular mechanisms of interfacial interaction of minerals and bioleaching microorganisms. (1) By studying the speciation transformation of iron/copper/sulfur on the mineral surface, the evolution of cell surface properties and EPS composition, the evolution of microbial community structure, and the evolution of expression of key oxidase genes during bioleaching, to characterize the adaptation process and therein the effects of it on the specific sulfur oxidation efficiency of bioleaching; (2) by in-situ characterization of the evolution of chalcopyrite surface microstructure, chemical speciation and the biofilm formation, to illustrate the specific adsorption and the relationship between cell growth/biofilm formation and the structure and speciation on the defect mineral surface; (3) by studying the utilization, transformation and activation of S⁰, which is one of the major intermediates during bioleaching, and the distribution of extracellular thiol groups and iron speciation, to evaluate in situ the sulfur activation mechanism; and (4) by comparative proteomics study of the extracellular and outmembrane proteins and looking up the genome sequence, to screen sulfur activation/transportation relevant proteins and genes.

Abstract: This paper describes selected capabilities of unconventional processing of steels in semi-solid state under various process conditions and with the use of various steel chemistries for obtaining unusual structures formed by rapid solidification in combination with other procedures. This investigation involves the use of severe plastic deformation techniques (SPD) and in-situ observation of the transformation of microstructure from solid state to semi-solid state at temperatures above 1200°C using a high-temperature microscope.

Abstract: Recovery processes responsible for evolution of microstructures in 0.1mm thin cold-drawn Ni-Ti shape memory alloy wire heat treated by DC electric pulse were investigated by combination of in-situ tensile stress - strain, electrical resistance and X-ray diffraction measurements. The X-ray data were used to obtain direct experimental information on the evolution of the phase fractions, internal strain and defects in the microstructure evolving through activation of a sequence of recovery processes during the short time electropulse treatment. It is shown that superelastic functional properties of the treated Ni-Ti wire can be precisely set by controlling the progress of the recovery processes by prescribing the time evolution of temperature T(t) and tensile stress s(t) (displacement control) in the treated wire.

Abstract: The scope of this work is the determination of single-crystals elastic constants (SEC) from X-ray diffraction lattice strains measurements performed on multi-phase polycrystals submitted to mechanical load through a bending device. An explicit three scales inverse self-consistent model is developed in order to express the SEC of a cubic phase, embedded in a multi-phase polycrystal, as a function of its X-ray Elasticity Constants. Finally, it is applied to a two-phases (α+β) titanium based alloy (Ti-17), in order to estimate Ti-17 β-phase unknown SEC. The purpose of the present work is to account the proper microstructure of the material. In particular, the morphologic texture of Ti-17 a-phase, i.e. the relative disorientation of the needle-shaped grains constituting this phase, is considered owing to the so-called Generalized Self-Consistent model.

Abstract: In this paper, the role of the pearlite-banded structure on fatigue crack growth behavior was investigated on carbon vessel plate material SA516, which is commonly used in the nuclear power plants. Along pearlite-banded orientation, in situ fatigue tests indicate that the crack initiated and propagated in the ferrite and then extended along the ferrite-pearlite interface when it met pearlitic colony. For comparison, the cyclic loading was also carried out perpendicular to the banding direction of the microstructure, and an intense crack branching was observed which led to fatigue crack retardation. Besides, the orientation perpendicular to banded pearlite in the investigated ferrite-pearlite steel was found to have a lower fatigue crack growth rate.

Abstract: Based on a coupled numerical and experimental approach, the design and implementation of an in situ thermal-gradient-controlled cyclic oxidation test, dedicated to the investigation of the TGO and TBC spallation, is presented. The influence of the specimen through thickness thermal gradient as well as the benefits of the video real-time monitoring of the cooling phase of an oxidation test is discussed in the case of the spallation of an alumina scale grown on FeCrAl alloys.