Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 567
Filtrar
1.
Dalton Trans ; 51(13): 5195-5202, 2022 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-35274652

RESUMO

Due to the small differences in the chemical properties of facial (fac) and meridional (mer) stereoisomers, selective synthesis of one of the isomers is challenging, especially for lanthanide complexes. By using a flexible bidentate phosphine oxide ligand, we managed to isolate three stereoisomeric 2D and 3D coordination polymers, in which six-coordinate Dy(III) ions possess fac- or mer-Cl3O3 coordination environments. Structural studies indicate that the stereochemistry differences result from their various supramolecular interactions (e.g., hydrogen bonding and π⋯π stacking). Magnetic property measurements reveal the different static and dynamic magnetic behaviours of the three stereoisomers. Ab initio CASSCF calculations were then performed which indicated that their distinct magnetic behaviours arise from their fac/mer configurations. Compared to fac-Dy(III), mer-Dy(III) possesses more axial ground-state KDs and higher first excited KDs.


Assuntos
Disprósio , Elementos da Série dos Lantanídeos , Cristalografia por Raios X , Disprósio/química , Elementos da Série dos Lantanídeos/química , Polímeros/química , Estereoisomerismo
2.
ACS Nano ; 16(4): 5647-5659, 2022 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-35312295

RESUMO

Challenges remain in precisely diagnosing the progress of liver fibrosis in a noninvasive way. We here synthesized small (4 nm) heterogeneous iron oxide/dysprosium oxide nanoparticles (IO-DyO NPs) as a contrast agent (CA) for magnetic resonance imaging (MRI) to precisely diagnose liver fibrosis in vivo at both 7.0 and 9.4 T field strength. Our IO-DyO NPs can target the liver and show an increased T2 relaxivity along with an increase of magnetic field strength. At a ultrahigh magnetic field, IO-DyO NPs can significantly improve spatial/temporal image resolution and signal-to-noise ratio of the liver and precisely distinguish the early and moderate liver fibrosis stages. Our IO-DyO NP-based MRI diagnosis can exactly match biopsy (a gold standard for liver fibrosis diagnosis in the clinic) but avoid the invasiveness of biopsy. Moreover, our IO-DyO NPs show satisfactory biosafety in vitro and in vivo. This work illustrates an advanced T2 CA used in ultrahigh-field MRI (UHFMRI) for the precise diagnosis of liver fibrosis via a noninvasive means.


Assuntos
Imageamento por Ressonância Magnética , Nanopartículas , Disprósio , Compostos Férricos , Humanos , Cirrose Hepática/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos
3.
Luminescence ; 37(5): 758-765, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35199460

RESUMO

In this work, the hydroxyapatite nanoparticles doped with trivalent dysprosium ions were synthesized by a co-precipitation method. The characterization techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) were carried out to determine the crystalline and structural properties. The Rietveld structural refinement of the XRD patterns confirmed the purity of the phase formation of the synthesized nanoparticles. The photoluminescence emission spectra exhibited intense emissions in the blue region at 450 nm and 476 nm along with less intense yellow emission at 573 nm which can be attributed to the magnetic dipole and electric dipole transitions of dysprosium respectively. In order to evaluate the colour tunability of the emitted light CIE chromaticity coordinate values were calculated. The intense blue emissions from the synthesized sample were found to be favourable for bioimaging. The images obtained from the fluorescence microscopy revealed that the dysprosium-doped hydroxyapatite nanoparticles are potential bioimaging probes in human cells.


Assuntos
Disprósio , Nanopartículas , Durapatita , Disprósio/química , Humanos , Luminescência , Nanopartículas/química , Difração de Raios X
4.
Luminescence ; 37(1): 141-152, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34738699

RESUMO

In the current investigation, a series of NaCa1-x PO4 :xDy3+ (x = 0.1, 0.3, 0.5, 0.7, 1.0, 1.5 and 2 mol%) phosphors were synthesized using a solution combustion method and citric acid as fuel. The investigated results from the X-ray diffraction (XRD) pattern showed phase purity of the synthesized material and orthorhombic crystal structure with space group Pna21. Photoluminescence properties of the synthesized phosphors were investigated. The synthesized Dy3+ -activated phosphor displayed blue (482 nm) and yellow (576 nm) emission under near-ultraviolet or blue excitations. These emission bands were ascribed due to the 4 F9/2 →6 H15/2 and 4 F9/2 →6 H13/2 transitions of Dy3+ ions. Commission International de l'Eclairage chromaticity coordinates showed emission in the near-white region for the proposed phosphors under different excitations. In addition, the current-voltage (I-V) characteristics of the NaCa1-x PO4 :xDy3+ (x = 1.5 mol%) phosphor-coated silicon solar cell and an uncoated solar cell were investigated under a solar simulator. The I-V characteristics of the proposed phosphor-coated silicon solar cell showed enhancement in solar cell efficiency by ~7.92%. The entire studies and their outcomes showed that synthesized phosphors have potential as white light emitting diodes and for solar applications.


Assuntos
Disprósio , Luminescência , Difração de Raios X
5.
Luminescence ; 37(2): 199-207, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34755458

RESUMO

A green chemical precipitation route was used to yield a hydrated basic sulfate precursor upon calcination at 1000°C into a series of (Y,Gd)2 O2 SO4 :Dy particles. The phosphors exhibited characteristic Dy3+ emissions from 4 F9/2 →6 HJ (J = 15/2, 13/2, 11/2) transitions under ultraviolet light excitation; the quenching concentration of Dy3+ was determined to be 2.5 at.%. Substitution of Gd3+ for Y3+ led to an additional strong sharp band at ~277 nm (8 S7/2 →6 IJ transition of Gd3+ ) in the photoluminescence excitation spectra, upon which the (Gd0.975 Dy0.025 )2 O2 SO4 phosphor achieved a ~2.8-fold higher photoluminescence intensity via an effective energy transfer from Gd3+ to Dy3+ compared with the 354 nm excitation of Dy3+ . Both the photoluminescence and photoluminescence excitation intensities of (Y,Gd)2 O2 SO4 :Dy phosphors increased with rising Gd3+ concentration and calcination temperature in the range 750-1000°C. A higher Gd3+ concentration slightly prolonged the effective fluorescence lifetime.


Assuntos
Disprósio , Luminescência , Transferência de Energia , Fluorescência , Sulfatos
6.
Environ Res ; 203: 111913, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34425112

RESUMO

The issue of effluent, especially organic colorants from several manufacturing units overlays an immense delinquent of the current epoch owing to its effect on oncogenic health hazards. Thus, Rare Earth Metal dysprosium (Dy) doped Zinc Ferrite (ZnFe2O4) were as-synthesized by a facile co-precipitation technique as an effectual nano photocatalyst intended to the amputation of these noxious dyes. The structural, functional, optical, magnetic, and degradation properties of this RE (Dy3+) doped ions were investigated using various characterizations, such as crystallite size (D) and several parameters (cation distribution, oxygen positional parameters, and bond length) were determined using XRD (X-ray diffraction) and it was found that as the dy3+ ion concentration increases the speck size decreased and the grain size remained within nano regime, which intern affects the surface area. From BET analysis it was found that on increasing the doping concentration, the surface area increases which pave a substantial role in the photo-Fenton activity. By using FT-IR (Fourier-transform infrared spectroscopy) various functional parameters (elastic, interionic bonds, ion distribution, etc.) were determined. Raman spectra had no extra peak formation which is seen to have pure phase formation of the as-synthesized samples. HR-TEM (High-Resolution Transmission Electron Microscopy analysis were done to determine the nature of the sample, the as-synthesized magnetic samples exhibit a polycrystalline formation with cubical agglomeration. The magnetic property was very significant for x = 0.10 concentration. As-synthesized (Fe0.9064Zn0.0936) [Fe1.0936Dy0.1Zn0.8064] O4) exhibits a momentous photo - Fenton activity against MB (Methylene blue), its removal efficiency was found to be 97.3% after 45 min. Also, this spinel ferrite acts as a magnetic recyclable catalyst even after 5 cycles with an insignificant lessening of elements and photo-Fenton activity.


Assuntos
Poluentes Ambientais , Nanopartículas , Disprósio , Compostos Férricos , Espectroscopia de Infravermelho com Transformada de Fourier , Zinco
7.
J Mater Chem B ; 10(2): 302-305, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34914815

RESUMO

Contrast agents retaining high relaxivities at ultrahigh magnetic fields underpin an enhanced image sensitivity within derived MRI scans. By varying the Dy3+ loading density inside a mesoporous silica architecture the dominant Curie effect can be effectively tuned so as to optimise T2 contrast at magnetic fields as high as 11.7 T.


Assuntos
Meios de Contraste/química , Compostos Radiofarmacêuticos/química , Dióxido de Silício/química , Disprósio/química , Campos Magnéticos , Porosidade , Temperatura
8.
J Environ Manage ; 300: 113697, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34543961

RESUMO

Dysprosium (Dy) is a rare earth element with a high economic and strategic value, and simultaneously an emerging contaminant, whose removal from wastewaters is gaining increasing attention. In this work, the Response Surface Methodology (RSM) combined with a Box-Behnken Design (3 factors-3 levels) was used to optimize the key operational conditions that influence the uptake of Dy by two living seaweed, Ulva sp. and Gracilaria sp.. The initial concentration of Dy (10-500 µg/L), water salinity (10-30), and seaweed dosage (0.5-5.5 g/L) were the independent variables, while the removal efficiency (%) and bioaccumulation (q, µg/g) were the response variables. Results highlighted the high capacity of both species to capture Dy. After 168 h, the optimal conditions that led to a maximum of 91 % of Dy removed by Gracilaria sp. were: 500 µg of Dy per L of water, salinity 10, and 5.5 g of seaweed per L. For Ulva sp., a maximum removal percentage of 79 % was achieved in the conditions: any initial concentration of Dy, salinity 20, and seaweed dosage of 3.7 g/L. Independently of the species, the response surfaces showed that the most important variable for the removal is the seaweed dosage, while for bioaccumulation is the initial concentration of Dy. Using RSM, it was possible to obtain the optimal operating conditions for Dy removal from waters, which is a fundamental step toward the application of the proposed technology at large scale.


Assuntos
Alga Marinha , Ulva , Poluentes Químicos da Água , Disprósio , Água , Poluentes Químicos da Água/análise
9.
Molecules ; 26(14)2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34299654

RESUMO

A tripodal Schiff base ligand, 2,4,6-Tris(4-carboxybenzimino)-1,3,5-triazine (MT) and its trinuclear Dy(III), Er(III), and Gd(III) complexes were synthesized. These were characterized using UV-visible, IR, 1H, and 13C NMR spectroscopies, elemental analysis, and molar conductivity measurements. The spectral studies indicate that the ligand is hexadentate and coordinates to the Ln(III) ions through the oxygen atoms of the carboxylic group. The trinuclear complexes were characterized as being bridged by carboxylate anions to the Dy(III), Er(III), and Gd(III) salen centers and displaying a coordination number of six. Biological studies revealed that MT is more active against the test micro-organisms relative to the trinuclear complexes. Acute toxicity studies revealed that MT is safe and has a wide range of effective doses (ED50). In vivo antimalarial studies indicate that MT could serve as an effective antimalarial agent since it has parasitemia inhibition of 84.02% at 50 mg/kg and 65.81% at 25 mg/kg, close to the value (87.22%) of the standard drug-Artesunate. Molecular docking simulation studies on the compounds against SARS-CoV-2 (6Y84) and E. coli DNA gyrase (5MMN) revealed effective binding interactions through multiple bonding modes. The binding energy calculated for Er(III)MT-6Y84 and Er(III)MT-5MMN complexes showed active molecules with the ability to inhibit SARS-CoV-2 and E. coli DNA gyrase.


Assuntos
Triazinas/química , Triazinas/farmacologia , Ânions/química , Ácidos Carboxílicos/química , Simulação por Computador , Complexos de Coordenação/química , Cristalografia por Raios X/métodos , Disprósio/química , Érbio/química , Gadolínio/química , Elementos da Série dos Lantanídeos/química , Ligantes , Espectroscopia de Ressonância Magnética/métodos , Simulação de Acoplamento Molecular , Estrutura Molecular , Bases de Schiff/química , Triazinas/síntese química
10.
Bioorg Chem ; 115: 105204, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34325217

RESUMO

In this study for the first time, high efficient, eco-friendly and novel Dy2O3/ZnO-Au ternary nanocomposites (Dy/ZnO-AuNCs) were prepared in presence of pomegranate fruit (PF) extract as capping and reducing agents (Dy/ZnO-AuNCs@PF). The influence of various parameters such as basic agents, reducing agents, sonication power, and sonication time were performed to reach the optimum condition. The formation of the products was characterized by FT-IR, HRTEM, XRD, FE-SEM, TEM, EDX and DRS techniques. The XRD and TEM analysis showed that the morphology and crystallite size of nanocomposites were spherical morphology and 85-90 nm, respectively. The obtained Dy/ZnO-AuNCs@PF were investigated as a nanocatalyst for degradation of erythrosine (ES) as anionic dye and basic violet 10 (BV10) as cationic dye under UV and visible light irradiations. The Dy/ZnO-AuNCs@PF exhibited higher photodegradation against ES (89.6%) and BV10 (91.3%) than pure Dy2O3 (63.1% for ES, 66.5% for BV10) and Dy2O3/ZnO (64.5% for ES, 70.8% for BV10) under UV irradiation. It was found that gold nanoparticles have significant effect on Dy/ZnO-AuNCs@PF catalytic performance for decomposition of organic pollutants. In addition, Dy/ZnO-AuNCs@PF showed excellent in-vitro antibacterial activity against A. baumannii, S. aureus and P. mirabilis with MIC and MBC values of (5, 80 mg/ml), (5, 40 mg/ml) and (2.5, 20 mg/ml), respectively. Generally, according to its excellent antibacterial and catalytic activity, Dy/ZnO-AuNCs@PF can be used in biomedical and environmental applications.


Assuntos
Antibacterianos/farmacologia , Disprósio/farmacologia , Ouro/farmacologia , Nanocompostos/química , Extratos Vegetais/farmacologia , Óxido de Zinco/farmacologia , Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Catálise , Relação Dose-Resposta a Droga , Disprósio/química , Frutas/química , Ouro/química , Química Verde , Testes de Sensibilidade Microbiana , Estrutura Molecular , Processos Fotoquímicos , Extratos Vegetais/síntese química , Extratos Vegetais/química , Romã (Fruta)/química , Proteus mirabilis/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Relação Estrutura-Atividade , Óxido de Zinco/química
11.
Chem Commun (Camb) ; 57(63): 7818-7821, 2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34278395

RESUMO

Tapping into the secondary coordination environment of mononuclear DyIII-complexes leads to drastic changes in luminescence and magnetism. Visualization of effects induced by stereoelectronics on the opto-magnetic properties was achieved through subtle modifications in the ligand framework.


Assuntos
Complexos de Coordenação/química , Disprósio/química , Campos Magnéticos , Estrutura Molecular , Imagem Óptica , Estereoisomerismo
12.
Chemosphere ; 280: 130600, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33940453

RESUMO

The high demand for greener energy and technological innovation require some crucial elements, such as the rare earths Nd and Dy. Being considered two of the most critical elements (high supply risk), it is vital to recover them from wastes/wastewaters, for later reuse. Here, the influence of operational parameters, such as biosorbent stock density (0.5, 3.0, and 5.5 g L-1), ionic strength (salinity 10 and 30) and contact time (24, 72 and 168 h), in the biosorption/bioaccumulation of Nd and Dy by two living marine macroalgae was evaluated in artificial seawater, seeking the improvement of the process. Results demonstrated that stock density is the most influential parameter, while the ionic strength showed to be a selective parameter, with a major influence only for Dy removal, which can be attributed to the different chemical characteristics observed between light rare earth elements (LREE) and heavy rare earth elements (HREE). For the ranges studied, the greatest removal/recovery for Gracilaria sp. was achieved with a stock density of 3.0 g L-1 at salinity 10, after 72 h for both REEs. For Ulva lactuca optimal conditions were: stock density of 5.5 g L-1 at salinity 10 with a contact time of 72 h for both REEs. Between species, U. lactuca showed to be the most promising, with removal efficiencies up to 98% for Nd and 89% for Dy. Findings substantiate the potential of the proposed process for obtaining Nd and Dy from secondary sources, particularly from low-level contaminated waters.


Assuntos
Metais Terras Raras , Alga Marinha , Ulva , Poluentes Químicos da Água , Disprósio , Neodímio , Poluentes Químicos da Água/análise
13.
Molecules ; 26(4)2021 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-33672166

RESUMO

The search for two- and three-dimensional materials with slow relaxation of the magnetization (single-ion magnets, SIM and single-molecule magnets, SMM) has become a very active area in recent years. Here we show how it is possible to prepare two-dimensional SIMs by combining Dy(III) with two different anilato-type ligands (dianions of the 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone: C6O4X22-, with X = H and Cl) in dimethyl sulfoxide (dmso). The two compounds prepared, formulated as: [Dy2(C6O4H2)3(dmso)2(H2O)2]·2dmso·18H2O (1) and [Dy2(C6O4Cl2)3(dmso)4]·2dmso·2H2O (2) show distorted hexagonal honeycomb layers with the solvent molecules (dmso and H2O) located in the interlayer space and in the hexagonal channels that run perpendicular to the layers. The magnetic measurements of compounds 1, 2 and [Dy2(C6O4(CN)Cl)3(dmso)6] (3), a recently reported related compound, show that the three compounds present slow relaxation of the magnetization. In compound 1 the SIM behaviour does not need the application of a DC field whereas 2 and 3 are field-induced SIM (FI-SIM) since they show slow relaxation of the magnetization when a DC field is applied. We discuss the differences observed in the crystal structures and magnetic properties based on the X group of the anilato ligands (H, Cl and Cl/CN) in 1-3 and in the recently reported derivative [Dy2(C6O4Br2)3(dmso)4]·2dmso·2H2O (4) with X = Br, that is also a FI-SIM.


Assuntos
Benzoquinonas/química , Complexos de Coordenação/química , Disprósio/química , Modelos Moleculares , Estrutura Molecular
14.
Luminescence ; 36(5): 1159-1171, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33683003

RESUMO

In present work, KNa(SO4 ) phosphors doped with different concentrations of rare earth Eu3+ , Sm3+ and Dy3+ ions (0.05, 0.1, 0.3, 0.5, 0.7, 1 mol%) were synthesized using a solid-state diffusion technique. Photoluminescence (PL) investigations were carried out for the whole range of Eu3+ , Sm3+ and Dy3+ -doped phosphors; rare earth ions that retained maximum PL intensity were selected for advanced anionic exchange. In the present investigation, phosphors KNa(SO4 ):Eu3+ (1 mol%), KNa(SO4 ):Dy3 + (0.5 mol%) and KNa(SO4 ):Sm3+ (0.3 mol%) had the highest PL intensity, and were therefore selected for further anionic substitution of sulphate anions with different concentrations of vanadate, phosphate, and tungstate anions, such as KNa(SO4 )1-x (MO4 )x : W (where W = Eu3+ 1 mol%, Dy3+ 0.5 mol% and Sm3+ 0.3 mol%; MO4 = PO4 , VO4 , WO4 ; and x = 0.1, 0.3, 0.5, 0.7, 1). Structural and molecular environments of the substituted phosphors were characterized individually using X-ray diffraction and Fourier transform infrared spectroscopy. In-depth morphological investigations of the prepared phosphors were undertaken using scanning electron microscopy. For the principal investigation on enhancement of white light-emitting diode (w-LED) performance, the PL properties of all the synthesized phosphors were studied analytically. Emission intensity ratios for KNa(SO4 ):Eu3+ 1 mol%, KNa(SO4 )0 (PO4 )1 :Eu 1 mol%, KNa(SO4 )0.9 (VO4 )1 :Eu 1 mol%, and KNa(SO4 )0.9 (WO4 )0.1 :Eu 1 mol% were 1:1.15:1.23:0.08. PL intensity ratios for the phosphors KNaSO4 :Dy 0.5 mol% and KNa(SO4 )0.9 (PO4 )0.1:Dy 0.5 mol% was 1:2. The ratio of PL intensity was 1:3.2:0.8 for KNa(SO4 ):Sm 1 mol%, KNa(SO4 )0.5 (PO4)0.5 :Sm 0.3 mol%, and KNa(SO4 )0.7 (VO4 )0.3 :Sm 0.3 mol% phosphors, respectively. Chromaticity investigations were carried out using Commission Internationale de l'Éclairage colour co-ordinate diagrams, which suggested that the prepared Eu3+ -doped and Sm3+ -doped phosphors would be prospective candidates for red and green LEDs, respectively, whereas Dy3+ -doped phosphors showed emission in the blue and yellow regions. The entire study indicated that amalgamation of anionic exchange at a KNaSO4 phosphor activated with Eu3+ , Dy3+ and Sm3+ rare earth ions could generate and enhance white light emission.


Assuntos
Európio , Luminescência , Disprósio , Estudos Prospectivos , Sulfatos
15.
Luminescence ; 36(5): 1209-1219, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33780141

RESUMO

To improve current multiphase white light emitting diodes (WLEDs), a novel series of five complexes consisting of one binary and four ternary complexes that emitted cool white light was successfully synthesized using a chelating tetradentate ligand and auxiliary ligands, i.e. 5,6-dimethyl-1,10-phenanthroline, 1,10-phenanthroline, 4,4'-dimethyl-2,2'-bipyridyl, and 2,2'-bipyridyl. The series was examined structurally using elemental analysis, Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, ultraviolet-visible spectroscopy, and proton nuclear magnetic resonance spectroscopy. These complexes had the appropriate thermal stability required for the generation of white organic LEDs (WOLEDs). Dysprosium (III) (Dy3+ ) ion complexes demonstrated the characteristic emission peaks of blue colour at 482 nm and yellow colour at 572 nm, respectively, when excited using near ultraviolet light. Band gap, refractive index, and decay lifetime of the optimized samples were recorded as 2.68 eV, 2.12, and 1.601 ms, respectively. Correlated colour temperature value (7875 K), Commission International de l'Eclairage coordinates (0.300, 0.294), and colour purity (21.04 × 10-2 ) of the optimized complex were near to those of white illuminants as defined by the National Television System Committee. These complexes had promise as commercial LEDs for the advanced optoelectronics devices, especially as WOLEDs for illumination applications.


Assuntos
Disprósio , Luminescência , Ligantes , Luz , Iluminação
16.
Dalton Trans ; 50(6): 2014-2017, 2021 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-33544105

RESUMO

pH is a critical parameter that has found unique application in magnetic resonance imaging (MRI) mapping acidity in tissues. This study reports a series of Dy-based MR probes that show innovative T2ex features, governed by proton catalyzed events. With an increase of pH from 5.5 to 8.0, the r2ex relaxivity increased dramatically, while the r1 relaxivity remained unchanged. The resulting r2ex/r1 allowed for concentration-independent and direct mapping of physiologically relevant pH ranges.


Assuntos
Amidas/química , Meios de Contraste/química , Disprósio/química , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos/química , Concentração de Íons de Hidrogênio
17.
Dalton Trans ; 50(4): 1307-1312, 2021 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-33399151

RESUMO

In complex [Na-Dy(µ2-L)4]n(HL = 8-hydroxyquinoline) (1), the DyL4 units were linked by the NaI ions to form one-dimensional chains. The chain exhibited slow magnetic relaxation behavior at low temperature, accompanied by obvious quantum tunneling of magnetization (QTM). Very weak fluorescence was detected in 1 due to the mismatch of the state energy between DyIII and the L ligand. Through the magnetic dilution of diamagnetic YIII ions, complex [NaDy0.02Y0.98(µ2-L)4]n (2) was obtained; in 2 the QTM of DyIII was suppressed and the single ion magnet (SIM) behavior was enhanced. More interestingly, the fluorescence emission of 8-hydroxyquinoline was lightened by the YIII ions in 2, whose intensity is linearly correlated with the temperature variation. The examples of dual functional fluorescent thermometers and SIM materials are attained simply by ion dilution, achieving the effect of killing two birds with one stone.


Assuntos
Corantes/química , Disprósio/química , Oxiquinolina/química , Sódio/química , Termômetros , Ítrio/química , Fluorescência , Íons/química , Fenômenos Magnéticos , Modelos Moleculares
18.
Ecotoxicol Environ Saf ; 208: 111588, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396111

RESUMO

Rare earth elements (REEs) have been recently identified as emergent contaminants because of their numerous and increasing applications in technology. The impact of REEs on downstream ecosystems, notably aquatic organisms, is of particular concern, but has to date been largely overlooked. The purpose of this study was thus to evaluate the toxicity of lanthanide metals, lutetium (Lu) and dysprosium (Dy) in rainbow trout after 96 h of exposure. The lethal concentration (LC50) was determined and the expression of 14 genes involved in different pathways such as oxidative stress, xenobiotic detoxification, mitochondrial respiration, DNA repair, protein folding and turnover, inflammation, calcium binding and ammonia metabolism were quantified in surviving fish. In parallel, lipid peroxidation (LPO), DNA damage (DSB), metallothionein level (MT) and cyclooxygenase activity (COX) were examined. The acute 96 h-LC50 data revealed that Lu was more toxic than Dy (1.9 and 11.0 mg/L, respectively) and was able to affect all investigated pathways by changing the expression of the studied genes, to the exception of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST). It also induced a decrease in DNA repair at concentrations 29 times below the LC50. This suggests that Lu could trigger a general stress to disrupt the cell homeostasis leading to genotoxicity without promoting oxidative stress. However, Dy induced modulation in the expression of genes involved in the protection against oxidative stress, detoxification, mitochondrial respiration, immunomodulation, protein turnover and an increase in the DNA strand breaks at concentrations 170 times lower than LC50. Changes in mRNA level transcripts could represent an early signal to prevent against toxicity of Dy, which exhibited inflammatory and genotoxic effects. This study thus provides useful knowledge enhancing our understanding of survival strategies developed by rainbow trout to cope with the presence of lanthanides in the environment.


Assuntos
Disprósio/toxicidade , Lutécio/toxicidade , Oncorhynchus mykiss/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Catalase/metabolismo , Dano ao DNA , Reparo do DNA , Disprósio/metabolismo , Ecossistema , Glutationa Transferase/metabolismo , Dose Letal Mediana , Peroxidação de Lipídeos/efeitos dos fármacos , Lutécio/metabolismo , Metalotioneína/metabolismo , Metais Terras Raras , Oncorhynchus mykiss/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Superóxido Dismutase/metabolismo
19.
Luminescence ; 36(4): 914-922, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33458929

RESUMO

A series of SrMg2 (PO4 )2 :Eu2+ -Eu3+ ,Dy3+ phosphors was synthesized successfully using a high-temperature solid-state method in an air atmosphere. The structures were studied in detail using X-ray diffraction (XRD) and the luminescence properties of the samples. SrMg2 (PO4 )2 :Eu2+ -Eu3+ samples can emit adjustable blue-violet light by controlling the proportion of dopant concentration of europium and dysprosium under 340 nm excitation. Dy3+ exhibits typical blue and yellow emission under 350 nm excitation. The energy transferred from Eu3+ to Dy3+ in Dy and Eu co-doped system was determined by comparing the fluorescence spectra of single-doped system. In addition, the colour coordinates of the International Commission on lighting (CIE) indicated that SrMg2 (PO4 )2 :Eu2+ -Eu3+ ,Dy3+ could be considered as a potential blue-purple phosphor for white light-emitting diode applications.


Assuntos
Disprósio , Luminescência , Európio , Luz , Difração de Raios X
20.
Chemosphere ; 263: 127882, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32818846

RESUMO

This study reports the distribution, contamination level, and possible sources of 54 metal (oid)s in the soils found around brick kilns in south-western Bangladesh. In total, 40 soil samples were collected from the vicinity of five brick kilns in four directions at 250 m intervals. This study reveals that the mean respective concentrations of caesium (Cs), beryllium (Be), lead (Pb), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), dysprosium (Dy), holmium (Ho), terbium (Tb), erbium (Er), thulium (Tm), ytterbium (Yb), thorium (Th), germanium (Ge), yttrium (Y), zirconium (Zr), niobium (Nb), silver (Ag), hafnium (Hf), tantalum (Ta), and tungsten (W), were 7.83, 3.19, 22.93, 85.93, 9.61, 36.86, 7.30, 1.23, 5.76, 1.13, 0.99, 3.14, 0.45, 2.91, 17.72, 3.04, 30.07, 185.13, 13.99, 0.30, 5.34, 1.26, and 2.61 µg g-1. Furthermore, those amounts exceeded their respective shale values. The pollution evaluation indices indicated a moderate level of contamination by Cs, Pb, Th, Ag, Hf, Ta, W, and lanthanides but excluding lanthanum (La) and lutetium (Lu). The pollution load index revealed pollution at two brickfields. Multivariate statistics reported that coal combustion in the brick kilns is the primary source of lanthanides, actinides, Y, Zr, and Hf in the soil, while other elements derived mostly from natural sources. A portion originated from coal combustion in brick kilns and agricultural activities. Changes in metal (oid)s concentrations were non-linear with the distance between the kilns and sampling points. Consequently, further studies are required and should consider meteorological factors and severity of human impact in the study area.


Assuntos
Oligoelementos , Bangladesh , Disprósio , Humanos , Praseodímio , Solo , Oligoelementos/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...