Effect of Ca on HoPO4·nH2O (n = 1 and 2) crystallization from phosphoric acid solution

Ca‐substituted holmium phosphate, isomorphic with tetragonal form of HoPO₄·H₂O was synthesized by crystallization from boiling phosphoric acid (2 M H₃PO₄) solution containing 0.02M of Ho and 0–0.2 M of Ca. Calcium concentration, higher than 0.2 M Ca in solution resulted in biphasic solid crystallization: tetragonal HoPO₄·H₂O and orthorhombic HoPO₄·2H₂O. Ca incorporation in the solid according to substitution mechanism: Ca²⁺ + H⁺ ↔ Ho³⁺ was limited to ∼3 wt.% and was coupled with simultaneous incorporation of HPO₄²⁻. Ca for Ho substitution caused an expansion of the tetragonal unit cell of HoPO₄·H₂O, resulted from differences in the ionic radii (r_Ca > r_Ho). Effects of thermal treatment at 900 °C were as follows: (i) the orthorhombic admixture of HoPO₄·2H₂O re‐crystallized into tetragonal anhydrous HoPO₄, (ii) Ca–at first dissolved in crystal structure of HoPO₄·H₂O was expelled from it during re‐crystallization to form Ca(PO₃)₂, and that was associated with a contraction of the unit cell; a ‐ and c‐ axes went down to the level of Ca‐free anhydrous tetragonal form of HoPO₄. (iii) HPO₄²⁻ present in the solids as prepared underwent condensation according to reaction 2HPO₄²⁻ → P₂O₇⁴⁻ + H₂O. Scanning electron micrographs revealed significant changes in size and morphology of the crystals ranging from spherical globules of HoPO₄·H₂O formed in Ca‐free H₃PO₄ with increasing diameter in the presence of lower Ca concentration to rod‐like crystals organized in bundles resembling the “scheaf of wheat”, while crystallized from phosphoric acid solution with higher than 0.2 M Ca.     

Crystallographic and structural characterization of heterometallic platinum compounds. Part II. Heterobinuclear Pt compounds with Pt?M (M = transition or lantanide metal) > 3.0 ?

This review covers almost two hundred and twenty heterobinuclear platinum compounds in which Pt?M separation is over 3.0 ?. The M is a transition metal (Cu, Ag, Au, Ti, V, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni and Pd). There is an example of a lanthanide, Yb and a actinide, U. The Pt atom has oxidation numbers 0, +2 and +4. The Pt coordination geometries include trigonal planar Pt(0); square planar Pt(II); trigonal bipyramidal, and pseudo octahedral Pt(IV), with the most frequent being square planar. The most common ligands for Pt are P and C donor atoms, as well as a chlorine atom. The Pt ?? Ag distance of 3.002(1) ? is the shortest found in this series. There are examples which contain two crystallographically independent molecules, which differ mostly by degree of distortion and even one unique example, which contains eight such molecules. These are examples of distortion isomerism. Factors affecting bond lengths and angles are discussed and some ambiguities in coordination polyhedral are outlined.     

Nickel-induced magnetic behaviour of nano-structured α-Fe2O3, synthesised by facile wet chemical route

We report the synthesis of pristine and nickel containing iron oxide (α-Fe₂O₃) nanocrystallites by facile environmentally benign wet chemical process. The magnetic behaviour of the samples has been found to change progressively with nickel content. The Mössbauer spectra revealed the precipitation of secondary phase of nickel ferrite (NiFe₂O₄) at ～2?wt% nickel contents. The transmission electron micrographs together with asymmetric magnetic hysteresis loop have confirmed the formation of core–shell structure. The Morin temperature of nanostructured α-Fe₂O₃ as estimated by superconducting quantum interference device has been found to be 257, 245, 247 and 242?K at nickel content of 0, 1, 2 and 4?wt%, respectively. The similar trends of increase/decrease in Morin temperature have been noticed by Mössbauer analysis. Furthermore, below Morin temperature, the temperature range of coexisted antiferromagnetic and ferromagnetic states has been found to increase with increase in nickel content.     

Nose-cone calorimeter: PHENIX forward upgrade

PHENIX is a high rate experiment efficient at measuring rare processes, but has limited acceptance in azimuth and pseudorapidity (η). The Nose Cone Calorimeter (NCC), a W–Si sampling calorimeter in the region of 0.9<η<3, is one of the upgrades which will significantly increase coverage in both azimuth and pseudorapidity. The NCC will expand PHENIX’s precision measurements of electromagnetic probes in η, reconstruct jets, perform a wide scope of correlation measurements, and enhance triggering capabilities. The detector will significantly contribute to measurements of γ-jet correlations, quarkonia production, and low-x nuclear structure functions. This report discusses details of the detector design and its performance concerning a sample of the physics topics which will benefit from the NCC. In view of recent funding difficulties, outlook of the activities is discussed.     

Investigation of heavy-metal accumulation in selected plant samples using laser induced breakdown spectroscopy and laser ablation inductively coupled plasma mass spectrometry

Single-pulse Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Ablation Inductively Coupled Plasma Mass-Spectrometry (LA-ICP-MS) were applied for mapping the silver and copper distribution in Helianthus Annuus L. samples treated with contaminant in controlled conditions. For Ag and Cu detection the 328.07 nm Ag(I) and 324.75 nm Cu(I) lines were used, respectively. The LIBS experimental conditions (mainly the laser energy and the observation window) were optimized in order to avoid self-absorption effect in the measured spectra. In the LA-ICP-MS analysis the Ag 107 and Cu 63 isotopes were detected. The capability of these two analytical techniques for high-resolution mapping of selected trace chemical elements was demonstrated.     

Isolation of Biogenic Amines Using Paramagnetic Microparticles Off-Line Coupled with Ion Exchange Liquid Chromatography

This study aims at the possibility of single structured paramagnetic microparticles (PMPs), composed of maghemite (γ-Fe₂O₃) core modified with chitosan called MAN8, or tetraethyl orthosilicate covered with Dowex called MAN35, to be helpful for isolation of biogenic amines prior to their further analysis. Primarily, we synthesized and characterized PMPs. To obtain the information about bead morphology, scanning electron microscopy was employed. Furthermore, X-ray fluorescence was employed to carry out the elemental composition analyses. To obtain further insight into interaction between PMP surface and biogenic amines, scanning electron microscope was employed. It was shown that binding of biogenic amines causes increase of relative current response of deprotonated microparticles. We tested the specificity of PMPs to bind biogenic amines on histamine, tyramine, spermine, spermidine, putrescine, and cadaverine. We found that two types of our PMPs were able to selectively bind spermidine, cadaverine, and histamine in the case of MAN35; and histamine, tyramine, and putrescine in the case of MAN8. Finally, we carried out the analyses of real samples obtained from patients suffering from prostate carcinoma, where histamine was determined as the most abundant biogenic amine (10.456–13.654 µg mL⁻¹). The prepared PMPs were able to isolate the biogenic amines from real samples, and thus they may be helpful in construction of biosensors, or Lab-on-a-Chip platforms, enabling less painful, and more rapid diagnosis of prostate cancer.

     

Microporous carbon fibers prepared from cellulose as efficient sorbents for removal of chlorinated phenols

Research on Chemical Intermediates - Cellulose-based microporous carbon fibers (CFs) were evaluated for the adsorption of 2-Chlorophenol (CP), 2,4-Dichlorophenol (DCP), and 2,4,6-Trichlorophenol...     

Development of new classes of plasmon active nano-structures and their application in bio-sensing and energy guiding

Metal nanostructures exhibit special optical resonance modes originating fronl tile subwavelengt.h confinement of conductive electrons in the material. These resonance modes represent a strong research focus due to their application potential in optics and sensing application, in this short review recent achievements of our group in this field are highlighted. A wet-chemistry approach synthesis of advanced metallic nanostruetures will be introduced and their exact positioning and manipulation by electric field is shown. Next. the application of these nanostructures for a detection of small molecules will be described in several examples. Also, it will be shown that inetal nanostruetures can be used for sub-wavelength light focusing and for efficient energy coupling into polymer chains.     

Synthesis of substituted tetrahydro-1,3-oxazines

A number of mono-, di-, tri-, and tetrasubstituted tetrahydro-1,3-oxazines were synthesized by the reaction of 3-amino- and 3-methylamino-1-propanols with aldehydes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 467–471, April, 1973.     

Synthesis and three-dimensional structures of the cis and trans isomers of 3-methyl-1-tert-butyl-4-acetyl- and 3-methyl-1-tert-butyl-4-carbomethoxy-4-piperidols

The cis and trans isomers of 3-methyl-1-tert-butyl-4-acetyl- and 3-methyl-1-tertbutyl-4-carbomethoxy-4-piperidols, the three-dimensional configurations of which were established by means of their IR and UV spectra, were synthesized in order to study the interrelationship between the structure and reactivity of stereoisomeric piperidines.Translated from Khimiya Geterotsiklicheskikh Soedinenni, No.12, pp. 1659–1665, December, 1973.