Search results for "CERAMICS"
showing 10 items of 1599 documents
Distinguishing the roles of carrier and biofilm in filtering media for the removal of pharmaceutical compounds from wastewater
2017
Abstract Pharmaceutical compounds (PCs) represent a large group of micropollutants in wastewaters (WW) worldwide. Many PCs are resistant to conventional WW treatment. Moreover, for some PCs the removal process is reversible. The aim of this study was to test three newly developed ceramic carriers for biofilm formation and PCs removal. The testing of untreated WW samples by liquid chromatography coupled to Orbitrap mass spectrometry allowed to detect the occurrence of 18 PCs in the range from 26 ng/L to 20,688 ng/L, with the highest concentrations found for caffeine. Besides, among PCs with concentrations above 1,000 ng/L, ibuprofen (19,234 ng/L), naproxen (1,405 ng/L), xylazine (1,366 ng/L)…
Influence of the anisotropy of sisal fibers on the mechanical properties of high performance unidirectional biocomposite lamina and micromechanical m…
2021
Abstract High performance biocomposites reinforced by sisal fibers, are between the most promising materials that could be used in various fields, from automotive to civil constructions, thanks to their good mechanical performance, as well as to the low cost and the great availability of the fiber. Nevertheless, at present their practical use is prevented by the limited knowledge of their mechanical performance. The results of the present study have shown that the intimate fibrillar structure of the sisal fiber is associated with a high anisotropy involving not only the elastic parameters, but also the damage processes with typical fiber splitting phenomena, that influence noticeably the bi…
The crystal structure of neodymium and europium chromate heptahydrate: Synthesis, infrared spectra, and thermal behavior of lanthanoid chromate hepta…
1991
Abstract The crystal structures of Nd2(CrO4)3 · 7H2O and Eu2(CrO4)3 · 7H2O were determined by the conventional single-crystal X-ray diffraction technique. In addition, unit cell dimensions were measured for La2 (CrO4)3 · 7H2O and Sm2(CrO4)3 · 7H2O. All these compounds are isostructural. Crystals are monoclinic, space group P2 1 c . For Nd2(CrO4)3 · 7H2O, a = 8.052(4) A, b = 19.143(4) A, c = 13.326(6) A, β = 128.15(4)°, Z = 4, Dx = 3.14 Mg · m−3, T = 296(1); and for Eu2(CrO4)3 · 7H2O, a = 7.965(3) A, b = 18.985(4) A, c = 13.185(4) A, β = 128.00(2)°, Z = 4, Dx = 3.29 Mg · m−3, T = 296(1). Ln atoms are nine-coordinated so that the coordination polyhedron is a tricapped trigonal prism for Ln1 a…
FRACTAL STRUCTURES IN SINGLE CRYSTALS OF FERROELECTRIC LITHIUM NIOBATE GROWN UNDER STRONGLY UNSTABLE CONDITIONS
2009
Atomic force microscopy studies of lithium niobate single crystals containing heterogeneously distributed lanthanide (Gd) admixture and a regular domain structure of 100 nm to 1 μm steps obtained under conditions of severe thermal instability have revealed fractal structures of the size of 10 to 100 nm within regions of the regular domain structures. A super-structure of clustered defects with 1–2 nm steps explaining results of Raman spectra analysis is supposed to exist in the cation sub-lattice and formation of periodic fractal structures of the size of ∼1 nm–100 μm is suggested to take place in lithium niobate single crystals containing lanthanide admixture.
MICRO- AND NANO-STRUCTURES IN SINGLE CRYSTALS OF LITHIUM NIOBATE CONTAINING LANTHANIDE ADMIXTURES
2008
ABSTRACT Micro-size domain structures in lithium niobate single crystals containing lanthanide (Gd, Tm, Sm, Lu) admixture, grown under stationary and non-stationary conditions are studied by efficient and flexible Thixomet® image analyser. Regular fractal-type domain structures observed along the three Y-axes of the hexagonal crystallographic set-up are assigned to pinning of the domain walls at defects created under conditions of imbalanced crystallization of the doped melt. Characteristic types of domains have been found analysing the configurations of domains on optical and atomic force microscopic images of surfaces of different crystallographic orientations.
Eu3+ ion distribution in oxyfluoride glass nanocomposites
2019
The authors are grateful to Dr. Andris Fedotovs for photography of the samples. This research is funded by the Latvian Council of Science, project “Novel transparent nanocomposite oxyfluoride materials for optical applications”, project No. LZP-2018/1-0335.
Influence of Ce codoping and H2 pre-loading on Er/Yb-doped fiber: Radiation response characterized by Confocal Micro-Luminescence
2011
International audience; Confocal microscopy luminescence measurements were applied to study the X-ray radiation response of Er/Yb-doped optical fibers in connection with H2 pre-loading and with the addition of another lanthanide element (Cerium) in the core composition. Laser excitations at 488 nm and 325 nm allow deriving the emission and absorption pattern of Er3+, the latter derived from the dips appearing in a wide luminescence band related to defects in silica. We found that the luminescence spectrum of the X-irradiated Er/Yb-doped core fiber evidences an increase in the emission intensity around 520 and 660 nm; in contrast, no changes are induced by radiation neither after H2 pre-load…
Hybrid organic-inorganic mononuclear lanthanoid single ion magnets
2019
The first family of hybrid mononuclear organic-inorganic lanthanoid complexes is reported, based on [PW11O39]7− and 1,10-phenanthroline ligands. This hybrid approach causes a dramatic improvement of the relaxation time (×1000) with a decrease of the optimal field while maintaining the Ueff of the inorganic analogues.
Extended dipyrrin ligands : candidates for optical metal ion detection under competitive conditions
2017
Acylhydrazone based extended dipyrrins L1-H and L2-H are introduced as complexometric ppb sensitive metal ion detectors. The binding of lanthanide, transition as well as post-transition metal ions is followed by UV-Vis measurements. The carbohydrate based ligand L2 is water soluble and thus can act as a metal ion sensor in this medium.
Slow magnetic relaxation in carbonato-bridged dinuclear lanthanide(iii) complexes with 2,3-quinoxalinediolate ligands
2012
The coordination chemistry of the 2,3-quinoxalinediolate ligand with different lanthanide(iii) ions in basic media in air affords a new family of carbonato-bridged M 2 III compounds (M = Pr, Gd and Dy), the Dy 2 III analogue exhibiting slow magnetic relaxation behaviour typical of single-molecule magnets. This journal is © 2012 The Royal Society of Chemistry.