Selective separation of yttrium from rare earth elements by ion interaction chromatography. Analytical and larger scale applications

ABSTRACT

New ion interaction chromatographic (IIC) method employing Kromasil 100 C₁₈ column and tetra-n-butylammonium hydroxide (TBAOH) as an ion interaction reagent (IIR) is able to separate yttrium from Rare Earth Elements (REE) as anionic complexes with nitrilotriacetic acid (NTA). New method for the chromatographic determination of Y in REE mixture was devised and validated by the analysis of the certified reference material (CRM). Potential possibilities of the new chromatographic system for larger scale applications including macro-micro events were demonstrated.     

Effect of internal stress on the fundamental reflectivity spectra of ZnTe thin films

The influence of internal stress on the fundamental reflectivity spectra of ZnTe thin films was considered. The internal stress was estimated from the shifts of the positions of the E₁, E₁ + Δ₁ and E₂ maxima in ZnTe reflectivity spectra, and was compared with “bending plate” method calculations for thin films of ZnTe.     

Thermal conductivity measurement of erythritol,xylitol, and their blends for phase change material design: A methodological study

This work presents and discusses a detailed thermal conductivity assessment of erythritol, xylitol, and their blends: 25 mol% erythritol and 80 mol% erythritol using the transient plane source (TPS) method with a Hot Disk Thermal Constants Analyzer TPS‐2500S. Thereby, the thermal conductivities of xylitol, 25 mol% erythritol, 80 mol% erythritol, and erythritol were here found for respectively in the solid state to be 0.373, 0.394, 0.535, and 0.589 W m^?1 K^?1 and in the liquid state to be 0.433, 0.402, 0.363, and 0.321 W m^?1 K^?1. These obtained results are comprehensively and critically analyzed as compared to available literature data on the same materials, in the phase change materials (PCMs) design context. This study clearly indicates that these thermal conductivity data in literature have considerable discrepancies between the literature sources and as compared to the data obtained in the present investigation. Primary reasons for these disparities are identified here as the lack of sufficiently transparent and repeatable data and procedure reporting, and relevant standards in this context. To exemplify the significance of such transparent and repeatable data reporting in thermal conductivity evaluations in the PCM design context, here focused on the TPS method, a comprehensive measurement validation is discussed along various residual plots obtained for varying input parameters (ie, the heating power and time). Clearly, the variations in the input parameters give rise to various thermal conductivity results, where choosing the most coherent result requires a sequence of efforts per material, because there are no universally valid conditions. Transparent and repeatable data and procedure reporting are the key to achieve comparable thermal conductivity results, which are essential for the correct design of thermal energy storage systems using PCMs.     

Untersuchungen zur Längssteifigkeit von Stahlstützen mit kastenförmigem Querschnitt

Experimental tests and theoretical analyses of longitudinal stiffness of closed cross‐sections steel columns. In structures made of thin‐walled elements it is of great importance to establish how the compressed elements change their stiffness while loading increases. Nonuniform change of longitudinal stiffness induces change of force and stress redistribution. More ductile elements take less loading and more stiff, tensed, ones are being overloaded. Columns with closed cross‐sections, box cross‐sections and hollow circular cross‐sections need to be distinguished from steel elements with longitudinal stiffness decreasing while loading increases. Shortening of column working in elastic‐plastic phase comes from material compression, cross‐section walls buckling and increased displacement of column as a whole. Imperfections that depend on fabrication process of cross‐section have a great influence on stiffness variation of an element. It can be designated, among other factors, from the equilibrium paths of tested elements. Those equilibrium paths, up to the limit point, were obtained by applying incremental method of numerical integration of equilibrium equations assuming initial displacements and residual stresses of column's walls and initial displacements of column's axes. Some numerical analyses were calculated using FEA software LUSAS. All theoretical analyses were verified by experimental tests carried out by the authors with full scale elements: box cross‐section columns – length 5280 mm, cold‐formed welded cross‐section columns – length 2000 mm. The research results and analyses by others were also used.     

In the normal repertoire of CD4+ T cells, a single class II MHC/peptide complex positively selects TCRs with various antigen specificities

In the thymus, immature T cells are positively and negatively selected by multiple interactions between their Ag receptors (TCRs) and self MHC/peptide complexes expressed on thymic stromal cells. Here we show that in the milieu of negative selection on physiological self class II MHC/peptide complexes (Abwt), a single class II/peptide complex AbEp52-68 positively selects a number of TCRs with various Ag specificities. This TCR repertoire is semidiverse and not biased toward Ep-like Ags. Our finding implies that the degeneracy of positive selection for peptide ligands exceeds peptide-specific negative selection and is essential to increase the efficiency and diversity of the repertoire so that T cells with the same Ag specificity can be selected by different self MHC/ peptide complexes.     

In situ synchrotron X-ray micro-tomography study of pitting corrosion in stainless steel

Pitting corrosion of stainless steel has been investigated with high-resolution in situ X-ray microtomography. The growth of pits at the tip of stainless steel pins has been observed with 3D microtomography under different conditions of applied current and cell potential. The results demonstrate how pits evolve in stainless steel, forming a characteristic “lacy” cover of perforated metal. In addition, it is shown how the shape of pits becomes modified by MnS inclusions.     

The Evaluation of the Possibilities of Using PLGA Co-Polymer and Its Composites with Carbon Fibers or Hydroxyapatite in the Bone Tissue Regeneration Process �C in Vitro and in Vivo Examinations

Synthetic polymers belonging to the aliphatic polyester group have become highly promising biomaterials for reconstructive medicine. The purpose of the present work is a biological evaluation of lactide-glycolide co-polymer (PLGA) and its composites with carbon fibers (PLGA+CF) or hydroxyapatite (PLGA+HA). The cytotoxicity of the evaluated materials towards hFOB 1.19 human osteoblast-like cells was assessed. Moreover, during the one-year contact of the assessed materials with living osseous tissue, the progress of bone formation was analyzed and the accompanying process of the materials’ degradation was evaluated. The materials under evaluation proved to be biocompatible.     

The influence of preparation techniques on the fundamental reflectivity spectra of thin ZnTe films

The dependence of the reflectivity coefficients of ZnTe textured thin films evaporated under various conditions in the energy range 3–6 eV was investigated. The analysed reflectivity spectra of thin films were compared with the reflection spectra of ideal monocrystals. Careful examination of these results suggests the influence of internal randomly distributed stresses introduced into the samples during the evaporation process and the cooling of the thin film-substrate system.     

A mass transfer model for the adsorption of pesticide on coconut shell based activated carbon

The adsorption isotherms of HCH on coconut shell based activated carbon type NP-5 at constant temperature have been experimentally measured. The porous properties such as, the density, BET surface area, pore size, pore volume along with pore distribution of NP-5 have been determined. The Freundlich’s, Langmuir’s, Temkin, Jovanovic and BET’s adsorption isotherm models describe of experimental data within the acceptable error ranges. The Freundlich, Jovanovic and Langmuir models were fitting better the experimental data. The shape of these isotherms indicates that the HCH is adsorbed as a monolayer and that there is no strong competition between the pesticide molecules and water to occupy the adsorption surface sites.     

An ENA state research committee: the Illinois experience

Henoch-Schoenlein purpura (HSP) is a common vasculitic disorder of childhood. Patients with this disorder typically present with palpable purpura or petechia associated with one or more of the following signs and symptoms: abdominal pain, arthritis/arthralgias, and nephritis. The diagnosis may be difficult to make, however, when a patient presents with isolated symptoms such as abdominal pain without the typical rash. A high index of suspicion must be maintained to diagnose HSP in this setting and to avoid unnecessary interventions. This report describes two unusual patients with the presenting complaint of abdominal pain who had delayed onset of the purpuric rash, making the diagnosis of HSP difficult.