Enhanced luminescence of Eu3+ in LaAl2B4O10 via energy transfer from Dy3+ doping.

In this study, an investigation was conducted on the structural and photoluminescence (PL) characteristics of LaAl2B4O10 (LAB) phosphors initially incorporated with Dy3+ and Eu3+ ions. Subsequently, the impact of varying Eu3+ concentration while maintaining a constant Dy3+ concentration was examined. Structural characterization was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). XRD analysis confirmed the effective embedding of both dopants into the hexagonal framework of the LAB. The PL emission spectra revealed characteristic emissions of Dy3+ (blue and yellow) and Eu3+ (red) ions. The optimized dopant concentrations of both Dy3+ and Eu3+ were observed to be 3 wt%. The dominant mechanism for concentration quenching in doped LAB phosphors was determined to be the electric dipole-dipole interaction. Co-doping with Eu3+ led to a substantial decrease in Dy3+ emission intensity (∼0.18-fold) while enhancing Eu3+ emission intensity (∼3.72-fold). The critical energy transfer distance (RC = 11.64 Å) and the analysis based on the Dexter theory confirmed that the energy transfer mechanism corresponds to dipole-dipole interaction. The color purities and correlated color temperatures (CCT) were estimated, suggesting the potential of these phosphors for warm white and red lighting applications, respectively. The observed energy transfer and luminescence properties, along with the structural and compositional characterization, highlight the promising potential of LAB:Dy3+/Eu3+ co-doped phosphors for advanced lighting and display technologies.

Novel Tb³âº-Doped LaAl2B4O10 phosphors: Structural analysis, luminescent properties, and energy transfer mechanism.

This study explores the structural and luminescent properties of terbium (Tb³âº)-doped lanthanum aluminium borate (LaAl2B4O10, abbreviated as LAB) phosphors, a novel host lattice for Tb³âº doping. LAB:Tb³âº phosphors, with varying dopant concentrations, were synthesized using a microwave-assisted combustion synthesis approach and characterized using X-ray diffraction (XRD), Rietveld refinement, and photoluminescence spectroscopy at both room and low temperatures. The structural analysis confirmed the hexagonal crystal structure of LAB and revealed successful incorporation of Tb³âº ions without altering the fundamental lattice. Luminescence studies demonstrated that the LAB:Tb³âº phosphors show strong green emission primarily attributed to the 5D4→7F5 transition of Tb³âº. The optimal doping concentration was determined to be 5 wt% Tb³âº, which provided maximum luminescence efficiency. This concentration also allowed for a critical study of energy transfer mechanisms within the phosphor, revealing dipole-dipole interactions with a critical distance of 9.80 Å between Tb³âº ions. Additionally, the CIE chromaticity coordinates of LAB:0.05 Tb³âº were precisely determined to be (0.289, 0.4460), indicating the potential for high-quality green emission suitable for solid-state lighting and display technologies. This work not only demonstrates the potential of LAB:Tb3+ as a highly efficient green luminescent material, but also sheds light on the mechanisms responsible for energy transfer and concentration quenching.

Temperature-dependent photoluminescence of novel Eu3+, Tb3+, and Dy3+ doped LaCa4O(BO3)3: Insights at low and room temperatures.

This study explores the structural and optical qualities of LaCa4O(BO3)3 (LACOB) phosphors doped with Eu3+, Dy3+, and Tb3+ using a microwave-assisted sol-gel technique. It uncovers oxygen-related luminescence defects in LACOB, highlighting emission peaks at 489 and 585 nm for Dy3+, a distinct sharp peak at 611 nm for Eu3+ in the red spectrum, and a notable green emission for Tb3+ due to specific transitions. The photoluminescence (PL) analysis indicates that luminescence is optimized through precise doping, leveraging dipole interactions, and localized resonant energy transfer, which are influenced by dopant concentration and spatial configuration. Temperature studies show emission intensity variations, particularly noticeable below 100 K for Tb3+ doped samples, demonstrating the nuanced balance between thermal quenching and luminescence efficiency. This temperature dependency, alongside the identified optimal doping conditions, underscores the potential of these materials for advanced photonic applications, offering insights into their thermal behavior and emission mechanisms under different conditions.

Temperature-responsive insights: Investigating Eu3+ and Dy3+ activated yttrium calcium oxyborate phosphors for structure and luminescence.

An investigation into the luminescent behavior of YCOB (Yttrium Calcium Oxyborate) doped with Eu3+ and Dy3+ ions, synthesized via the combustion method, is presented. The study, employing X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Energy-Dispersive X-ray Spectroscopy (EDS) analyses, confirms the structural integrity and purity of the synthesized nanophosphors. An XRD pattern exhibiting distinct crystalline peaks indicates that the dopant ions were successfully integrated into the YCOB lattice. The photoluminescence (PL) response of YCOB with Eu3+ and Dy3+ ions is thoroughly examined, uncovering distinct excitation and emission spectra. In the case of Eu3+ doping, excitation spectra reveal a significant charge transfer (CT) band at 254 nm, indicative of electron transfer between oxygen and europium ions. This CT transition enhances our understanding of the excitation behavior, with the dominant and Laporte-forbidden 5D0 → 7F2 transition. Characteristic peaks at 345 nm in the excitation spectra efficiently stimulate YCOB:Dy3+ when Dy3+ is used as a dopant. The primary emission peak at 585 nm corresponds to the hypersensitive electric dipole transition 4F9/2-6H13/2. Concentration quenching phenomena are observed, with a maximum Eu3+ concentration of 7 wt % attributed to the dipole-quadrupole interaction. Dy3+ doping, with a maximum concentration of 2 wt % primarily shows multipolar interactions, especially dipole-dipole interactions. The study extends to CIE chromaticity analysis, emphasizing Eu3+ doping's suitability for white light-emitting diode (WLED) applications and ensuring color stability. Conversely, varying Dy3+ concentrations do not yield consistent chromaticity coordinates. These findings have significant implications for the development of advanced phosphor materials across diverse applications, offering a roadmap for optimizing their optical performance.

Synthesis and photoluminescence characteristics of a novel Eu and Tb doped Li2MoO4 phosphor.

Li2MoO4:x Eu3+ and Li2MoO4:xTb3+ phosphors, where x = 0.5, 1, 2, 3, 5 and 7 wt%, were synthesized through a gel-combustion method. The XRD data reveals that Eu3+ and Tb3+ doped Li2MoO4 phosphors exhibit a Rhombohedral structure belonging to the space group R3 which matched well with the standard JCPDS files (No.012-0763). We present photoluminescence (PL) spectra from Eu and Tb doped Li2MoO4 under 349 nm Nd:YLF pulses laser excitation over the temperature range of 10-300 K. Undoped Li2MoO4 shows a wide broad band around 600 nm because of the intrinsic PL emission of tetrahedral of MoO42- which was in good agreement with previous findings. Under the excitation of 394 nm, the as-synthesized phosphors exhibited sharp and strong intensity PL emission signals in the red (612 nm, 5D0→7F2 transition) and green (544 nm, 5D4→7F5 transition), respectively. The critical doping concentration of Eu3+ and Tb3+ ions in the Li2MoO4 were estimated to be 2 wt%. The concentration quenching phenomena were discussed, and the critical distances for energy transfer have also been evaluated by the concentration quenching.

Policy capacities and effective policy design: a review.

Effectiveness has been understood at three levels of analysis in the scholarly study of policy design. The first is at the systemic level indicating what entails effective formulation environments or spaces making them conducive to successful design. The second reflects more program level concerns, surrounding how policy tool portfolios or mixes can be effectively constructed to address complex policy objectives. The third is a more specific instrument level, focusing on what accounts for and constitutes the effectiveness of particular types of policy tools. Undergirding these three levels of analysis are comparative research concerns that concentrate on the capacities of government and political actors to devise and implement effective designs. This paper presents a systematic review of a largely scattered yet quickly burgeoning body of knowledge in the policy sciences, which broadly asks what capacities engender effectiveness at the multiple levels of policy design? The findings bring to light lessons about design effectiveness at the level of formulation spaces, policy mixes and policy programs. Further, this review points to a future research agenda for design studies that is sensitive to the relative orders of policy capacity, temporality and complementarities between the various dimensions of policy capacity.

Structural and spectroscopic characterization of a new luminescent NiII complex: bis{2,4-dichloro-6-[(2-hydroxypropyl)iminomethyl]phenolato-κ3O,N,O'}nickel(II).

The design and preparation of transition-metal complexes with Schiff base ligands are of interest due to their potential applications in the fields of molecular magnetism, nonlinear optics, dye-sensitized solar cells (DSSCs), sensing and photoluminescence. Luminescent metal complexes have been suggested as potential phosphors in electroluminescent devices. A new luminescent nickel(II) complex, [Ni(C10H10Cl2NO2)2], has been synthesized and characterized by single-crystal X-ray diffraction and elemental analysis, UV-Vis, FT-IR, 1H NMR, 13C NMR and photoluminescence spectroscopies, and LC-MS/MS. Molecules of the complex in the crystals lie on special positions, on crystallographic binary rotation axes. The NiII atoms are six-coordinated by two phenolate O, two imine N and two hydroxy O atoms from two tridentate Schiff base 2,4-dichloro-6-[(2-hydroxypropyl)iminomethyl]phenolate ligands, forming an elongated octahedral geometry. Furthermore, the complex exhibits a strong green luminescence emission in the solid state at room temperature, as can be seen from the (CIE) chromaticity diagram, and hence the complex may be a promising green OLED (organic light-emitting diode) in the development of electroluminescent materials for flat-panel-display applications.

Crystal structure and photoluminescence properties of a new monomeric copper(II) complex: bis(3-{[(3-hydroxypropyl)imino]methyl}-4-nitrophenolato-κ3O,N,O')copper(II).

Copper(II)-Schiff base complexes have attracted extensive interest due to their structural, electronic, magnetic and luminescence properties. The title novel monomeric CuII complex, [Cu(C10H11N2O4)2], has been synthesized by the reaction of 3-{[(3-hydroxypropyl)imino]methyl}-4-nitrophenol (H2L) and copper(II) acetate monohydrate in methanol, and was characterized by elemental analysis, UV and IR spectroscopies, single-crystal X-ray diffraction analysis and a photoluminescence study. The CuII atom is located on a centre of inversion and is coordinated by two imine N atoms, two phenoxy O atoms in a mutual trans disposition and two hydroxy O atoms in axial positions, forming an elongated octahedral geometry. In the crystal, intermolecular O-H...O hydrogen bonds link the molecules to form a one-dimensional chain structure and π-π contacts also connect the molecules to form a three-dimensional structure. The solid-state photoluminescence properties of the complex and free H2L have been investigated at room temperature in the visible region. When the complex and H2L are excited under UV light at 349 nm, the complex displays a strong green emission at 520 nm and H2L displays a blue emission at 480 nm.

Soluble Klotho levels in diabetic nephropathy: relationship with arterial stiffness.

OBJECTIVE: In this cross-sectional study, we investigate the relationship between soluble Klotho (s-Klotho) levels, markers of bone mineral metabolism and arterial stiffness in 109 diabetic nephropathy patients (median age 61.00± 9.77 years) and 32 healthy controls (median age 49.23 ± 7.32 years). PATIENTS AND METHODS: Blood samples were collected to measure the levels of s-Klotho, and FGF23, serum creatinine, Calcium (Ca), Phosphorus (P), 25-hydroxyvitamin D3 (25hD) and parathyroid hormone (PTH). Pulse wave velocity (PWV) and blood pressure were also measured using a combined monitor. RESULTS: s-Klotho, FGF23 and PTH levels were significantly higher and 25hD was significantly lower in the patients than in controls (p < 0.001). Systolic blood pressure, pulse pressure and PWV were also significantly higher in the patients (p < 0.001). s-Klotho, FGF23 and 25hD levels significantly varied between sub-groups according to CKD stages, defined according to the CKD epidemiology collaboration equation. A strong positive correlation was found between s-Klotho and FGF23 (r = 0.768, p = 0.001) levels, but not with other bone mineral metabolism, blood pressure or arterial stiffness parameters. Creatinine levels significantly differed (p = 0.009) between three s-Klotho-level sub-groups, with the high creatinine levels in the sub-group with the lowest s-Klotho levels and estimated glomerular filtration rate (eGFR). CONCLUSIONS: There was no correlation between eGFR and s-Klotho levels. Arterial stiffness increased in CKD but was not related to s-Klotho or FGF23 levels. Among all parameters, FGF23 levels had the greatest effect on s-Klotho levels.

Increased oxidative stress in diabetic nephropathy and its relationship with soluble Klotho levels.

BACKGROUND: In the present study, we aimed to assess the relationship between the levels of soluble Klotho (s-Klotho) and oxidative stress markers in diabetic nephropathy patients with different stages of chronic kidney disease (CKD) and albuminuria levels. METHODS: We enrolled 109 patients with type 2 diabetes (mean age, 61.63 ± 9.77 years) and 32 healthy controls (mean age, 49.53 ± 7.32 years) between January and June 2014.  Patients were classified into three groups based on their urinary albumin/creatinine ratio (UACR). Blood samples were collected to measure the levels of s-Klotho, serum creatinine, calcium, phosphorus, 25-hydroxyvitamin D3, and parathyroid hormone (PTH). We used the total oxidant status (TOS), total antioxidant status (TAS), ischemia-modified albumin (IMA), and ischemia-modified albumin ratio (IMAR) values to measure the oxidative status. Moreover, the oxidative stress index (OSI) was estimated as the percentage ratio of TOS/TAS values. RESULTS: The TOS, TAS, and OSI values were significantly greater in the diabetic nephropathy patients compared to controls (p <0.001). When patients were classified based on their UACR, we noted that the TOS, OSI, and IMA values did not significantly differ, although the TAS (p <0.001), and IMAR (p =0.002) values significantly differed between the groups. The s-Klotho levels also significantly differed (p =0.031) between the groups. These s-Klotho levels exhibited a significant positive correlation with TOS (r =0.186, p =0.034) and OSI (r =0.207 p =0.018), but showed no correlation with the estimated glomerular filtration rate; UACR; HbA1c, calcium, phosphorus, and PTH levels; and TAS, IMA, and IMAR values. CONCLUSION: Oxidative stress is greater in patients with diabetic nephropathy, and the TOS was positively correlated with s-Klotho levels in diabetic patients. The therapeutic reduction of oxidative stress in patients with diabetic nephropathy could improve the renal and cardiovascular outcomes. Hippokratia 2016, 20(3): 198-203.

Antioxidant effect of propolis against exposure to chromium in Cyprinus carpio.

The aim of the present study was to investigate the ameliorative properties of propolis against the toxic effects of chromium (VI) by examining oxidative damage markers such as lipid peroxidation and the antioxidant defence system components in carp (Cyprinus carpio). The fish were exposed to sublethal concentrations of chromium. Propolis was simultaneously administered to chromium-exposed fish. Treatment was continued for 28 days, and at the end of this period, blood and tissue (liver, kidney, spleen, and gill) samples were collected. Levels of malondialdehyde (MDA) and reduced glutathione (GSH) as well as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were determined in blood and tissues for measurement of oxidant-antioxidant status. The levels of MDA, as an index of lipid peroxidation, increased in blood and tissues. Antioxidant enzyme activities in blood and tissues were modified in chromium groups compared to controls. Simultaneous administration of propolis ameliorated these parameters. The present results suggest that administration of propolis might alleviate chromium-induced oxidative stress.

Insulin-like growth factor-I gene polymorphism in acne vulgaris.

BACKGROUND: Acne vulgaris is a multifactorial disease of the skin. Several studies have shown that elevated levels of serum insulin-like growth factor-I (IGF-I) correlate with overproduction of sebum and acne. Recently functional relationship between IGF-I (CA) polymorphism and circulating IGF-I levels in adults has been reported. AIMS: The aim of our study was to investigate for the first time whether IGF-I (CA) polymorphism might be involved in the pathogenesis of acne or not. METHODS: We included 115 acne patients and 117 healthy subjects to the study. The clinical grade of acne was assessed based on the Global Acne Grading System. Participants were questioned about diabetes mellitus, PCOS and other systemic disease. We searched for the IGF-I (CA) 19 polymorphism in this study. The IGF-I (CA) 19 polymorphism was performed by polymerase chain reaction. RESULTS: We categorized the IGF-I (CA) 19 polymorphism area into three groups as lower than 192 bp, 192­194 bp and higher than 194 bp. We found that the frequency of genotype IGF-1 (CA) 19 gene was significantly different between control and acne patients (P = 0.0002). A significant association between IGF-I (CA) genotypes and severity of acne was found (P = 0.015). No significant difference was found between male and female patients (P > 0.05). CONCLUSIONS: Our results suggest that IGF-I (CA) 19 polymorphism may contribute to a predisposition to acne in Turkish patients.

A fast exhaustive search algorithm for rate-constrained motion estimation.

A fast exhaustive search algorithm for rate-constrained motion estimation is presented. The motion vectors are selected from a search window based on a rate-distortion criterion by successively eliminating the search positions depending on the rate constraint. The estimation performance of the proposed algorithm is identical to the performance of the rate-constrained full search algorithm, with considerable reduction in computation. Simulation results indicate that the number of matching calculations decreases as the constraint on the rate increases.