Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter

Timisoara, Romania

Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter

Timisoara, Romania
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Chirita M.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter | Ieta A.,State University of New York at Oswego
Crystal Growth and Design | Year: 2012

We developed a new procedure for synthesizing highly crystalline FeCO 3 by hydrothermal decomposition of the Fe(III)-EDTA complex in the presence of urea, starting from ferric ammonium sulfate and Na 4EDTA as the main precursors. Single phase FeCO 3 microcrystals with a size in the range of 50-200 μm have been obtained after high pressure-temperature treatment time between 15 and 26 h at 230 and 250 °C. Without changing the concentrations of the precursors and synthesis temperature, we have investigated the kinetics of phase transitions between 2 and 40 h of high pressure-temperature treatment time. A transition from hematite (in the first 4 h) to magnetite microoctahedrons with superparamagnetic behavior at room temperature, via a single phase of iron carbonate microcrystals, has been recorded. © 2011 American Chemical Society.


Gheju M.,Polytechnic University of Timişoara | Balcu I.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Journal of Hazardous Materials | Year: 2011

This work presents investigations on the total removal of chromium from Cr(VI) aqueous solutions by reduction with scrap iron and subsequent precipitation of the resulted cations with NaOH. The process was detrimentally affected by a compactly passivation film occurred at scrap iron surface, mainly composed of Cr(III) and Fe(III). Maximum removal efficiency of the Cr(total) and Fe(total) achieved in the clarifier under circumneutral and alkaline (pH 9.1) conditions was 98.5% and 100%, respectively. The optimum precipitation pH range which resulted from this study is 7.6-8.0. Fe(total) and Cr(total) were almost entirely removed in the clarifier as Fe(III) and Cr(III) species; however, after Cr(VI) breakthrough in column effluent, chromium was partially removed in the clarifier also as Cr(VI), by coprecipitation with cationic species. As long the column effluent was free of Cr(VI), the average Cr(total) removal efficiency of the packed column and clarifier was 10.8% and 78.8%, respectively. Our results clearly indicated that Cr(VI) contaminated wastewater can be successfully treated by combining reduction with scrap iron and chemical precipitation with NaOH. © 2011 Elsevier B.V.


Gheju M.,Polytechnic University of Timişoara | Balcu I.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Journal of Hazardous Materials | Year: 2010

Hexavalent chromium reduction with scrap iron has the advantage that two wastes are treated simultaneously. The reduction of hexavalent chromium by scrap iron was investigated in continuous system, using as reducing agent the following scrap iron shapes and sizes: (1) spiral fibers, (2) shavings, and (3) powder. The shape and size of scrap iron were found to have a significant influence on chromium and iron species concentration in column effluent, on column effluent pH and on Cr(VI) reduction mechanism. While for large scrap iron particles (spiral fibers) homogeneous reduction is the dominant Cr(VI) reduction process, for small scrap iron particles (powder) heterogeneous reduction appears to be the dominant reaction contributing to Cr(VI) reduction. All three shapes and sizes investigated in this work have both advantages and disadvantages. If found in sufficient quantities, scrap iron powder seem to be the optimum shape and size for the continuous reduction of Cr(VI), due to the following advantages: (1) the greatest reduction capacity, (2) the most important pH increase in column effluent (up to 6.3), (3) no chromium was detected in the column effluent during the first 60. h of the experiment, and (4) the lowest steady-state Cr(VI) concentration observed in column effluent (3.7. mg/L). But, despite of a lower reduction capacity in comparison with powder particles, spiral fibers and shavings have the advantage to result in large quantities from the mechanic processing of steel. © 2010 Elsevier B.V.


Ercuta A.,West University of Timișoara | Chirita M.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Journal of Crystal Growth | Year: 2013

Porous crystals of magnetite and vacancy-ordered maghemite, rhombohedron-shaped, reaching 150 μm in size, and having remarkably large specific surface area (88.55 m2/g for magnetite, 40.14 m 2/g for maghemite) were obtained via topotactical conversion, starting from hydrothermally grown siderite single crystals. The increase in density (from 3.9 g/cm3 for siderite to 5.24 g/cm3 for magnetite and 4.9 g/cm3 for maghemite) caused quasi-ordered internal pores-grains pattern, with mesocrystalline appearance. The X-ray Line-Profile Fitting-based microstructure analysis gave 64±6 nm and 84±8 nm for the average inner grains size in magnetite and maghemite. Structure and phase content analysis indicated high purity and crystallinity. Magnetic measurements indicated saturation magnetization (92.1 emu/g for magnetite and 85.5 emu/g for maghemite) approaching the upper limits reported for the pure bulk oxides. © 2013 Elsevier B.V.


Zamfir A.D.,West University of Timișoara | Zamfir A.D.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Advances in Experimental Medicine and Biology | Year: 2014

Gangliosides, sialylated glycosphingolipids, are particularly enriched in mammalian central nervous system where their expression is cell type-specifi c and changes particularly during brain development, maturation, aging, and diseases. For this reason, gangliosides are important diagnostic markers for various brain ailments, including primary and secondary brain tumors and neurodegenerative diseases. Among all biochemical and biophysical methods employed so far for ganglioside analysis, mass spectrometry (MS) emerged as one of the most reliable due to the sensitivity, accuracy, and speed of analysis as well as the possibility to characterize in details the molecular structure of the identifi ed biomarkers. This chapter presents signifi cant achievements of MS with either electrospray (ESI), chip-based ESI, or matrix-assisted laser desorption/ionization (MALDI) in the analysis of gangliosides in normal and diseased human brain. Specifi cally, the chapter assesses the MS contribution in determination of topospecifi city, fi logenetic, and brain development stage dependence of ganglioside composition and structure as well as in discovery of ganglioside markers in neurodegenerative/ neurodevelopmental conditions, primary and secondary brain tumors. The highlighted accomplishments in characterization of novel structures associated to severe brain pathologies show that MS has real perspectives to become a routine method for early diagnosis and therapy based on this biomolecule class. © 2014, Springer International Publishing Switzerland.


Van Staden J.K.F.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Talanta | Year: 2015

Phthalocyanines and metallophthalocyanines play a very important role in the metabolism of living organisms through biological pigments or biochromes and are therefore also employed in numerous applications in analytical chemistry. In flow-, and sequential-injection analysis and microfluidic systems the role of phthalocyanines and metallophthalocyanines is centered as either that of analyte or that of a reagent or modifier in the determination of other species. This paper covers the attributes of phthalocyanines and metallophthalocyanines complexes as enhancements in chemical analysis in flow- and sequential injection analysis and microfluidic systems and points out the advantages and disadvantages in the implementation thereof. © 2015 Elsevier B.V.


Herklotz A.,Oak Ridge National Laboratory | Rus S.F.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter | Ward T.Z.,Oak Ridge National Laboratory
Nano Letters | Year: 2016

The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. Charge density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques. © 2016 American Chemical Society.


van Staden J.F.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter | Stefan-van Staden R.I.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Talanta | Year: 2010

Porphyrins and metalloporphyrins fulfil a very important role in the metabolism of living organisms through biological pigments or biochromes and are therefore also employed in numerous applications in analytical chemistry. In flow-injection analysis the role of porphyrins and metalloporphyrins are centered as either that of analyte or that of a reagent or modifier in the determination of other species. This paper covers the attributes of porphyrin and metallophorphyrin complexes as enhancements in chemical analysis in flow-injection systems and points out the advantages and disadvantages in the implementation thereof. © 2009 Elsevier B.V. All rights reserved.


Van Staden J.F.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter | Van Staden R.I.S.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Talanta | Year: 2012

Dopamine (DA) is one of the most important catecholamine neurotransmitters in the human central nervous system in the brain and plays a key role in the functioning of the renal, hormonal, and cardiovascular systems. Abnormal levels of dopamine are related to neurological disorders, such as schizophrenia and Parkinson's disease and the control and fluctuations of the amount of dopamine are extremely important in monitoring with analytical systems in the human brain. This review covers the attributes of flow-injection analysis systems with different detection devices and other related techniques for the in vitro and in vivo determination of dopamine as neurotransmitter and points out the advantages and disadvantages in the implementation thereof. © 2012 Elsevier B.V. All rights reserved.


Zamfir A.D.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
Electrophoresis | Year: 2016

Proteoglycans (PGs) represent a class of heavily glycosylated proteins distributed in the extracellular matrix, connective tissues, and on the surface of many cell types where, as functional molecules, regulate important biological processes. Structurally, PGs consist of a core protein linked to glycosaminoglycan (GAG) chains, which basically determine the properties and activities of PGs. In view of the structural complexity of GAGs and the existing correlation between this structure and PG functions, systematic efforts are invested into development of analytical methods for GAG characterization. Although less popular and of higher technical difficulty than liquid-based chromatographic methods, CE coupled with ESI MS contributed lately an important progress to glycosaminoglycomics field. In this review article, the most significant CE ESI MS and MS/MS applications in GAG research are highlighted and critically assessed. The advantages and the limitations of each concept as well as the possible further methodological refinements are also concisely discussed. Finally, the review presents the perspectives of CE ESI MS in GAG analysis along with the objectives, which still need to be reached in the near future. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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