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Comparative investigations of gadolinium based borate glasses doped with Dy3+ for white light generations
摘要： Gadolinium-based borate glasses doped with Dy3+ ions were developed by melt quenching technique for white light generation. The title glasses were examined by XRD, optical absorption spectra and Photoluminescence spectra. From photoluminescence emission spectra, the higher intensity peak was observed at 575 nm (4F9/2 → 6H13/2) for present glass samples. The experimental decay rate (τexp) of 4F9/2 transition of Dy3+ ions were found to be a decline in increasing of Dy2O3 content. The Inokuti-Hirayama (IH) model is used to explain the non-exponential decay time by putting S=6, which confirmed that the energy is transfer through cross-relaxation is of dipole–dipole nature among the Dy2O3. The values of color coordinates match with the range of white light of chromaticity (CIE) diagram. The color chromaticity coordinates (u, v) and color correlated temperature (CCT) values for present glasses were correlated with standards, which are closely related to the standard, therefore, the prepared glasses might be helpful for different photonic applications such as white LEDs.
关键词： luminescence,glasses,borate,spectra,Gadolinium
更新于2025-09-23 15:23:52
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AIP Conference Proceedings [Author(s) 1ST INTERNATIONAL CONGRESS ON SOLAR ENERGY RESEARCH, TECHNOLOGY AND APPLICATIONS (ICSERTA 2018) - Ouarzazate, Morocco (8–10 May 2018)] - Synthesis and characterization of Gd-doped ZnO nanorods
摘要： Undoped and Gadolinium doped ZnO nanorods [Zn1-xGdxO] was studied with an aim to enhance and control its multifunctional properties for various optoelectronic or magnetoelectrical properties. After synthesizing well-defined Gd doped ZnO nanorods by hydrothermal route, evaluation of strurctural, optical, magnetic and electrical characterstics of synthesised ZnO nanorods was performed. Formation of hexagonal wurtzite was confirmed by X-Ray Diffraction studies. In magnetic studies RTFM behavior was observed for undoped as well as doped ZnO nanostructures. Four Probe method were conducted to study the electrical properties of samples. Effect of addition of dopant on band gap was shown by UV-Vis spectra.
关键词： DMS,RTFM,ZnO,Gadolinium
更新于2025-09-23 15:23:52
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Evolution of microstructures and optical properties of gadolinium oxide with oxygen flow rate and annealing temperature
摘要： In this study, the effects of oxygen flow rate and annealing temperature on Gd2O3 structures and optical properties were systematically analyzed. Gd2O3 films were deposited on both quartz and ZnS substrates by magnetron sputtering and then annealed under vacuum at 700, 800, and 900 (cid:1). Restructure and phase transformation from cubic to monoclinic occur at different temperatures depending on the oxygen flow rate. The optical band gap, which is more sensitive to the annealing temperature than oxygen flow rate changes from 5.32 to 5.65 eV. The refractive index is approximately 1.75 at 550 nm and is adjustable by the oxygen flow rate. The transmittance of the ZnS substrate with Gd2O3 film exceeds 80% and reaches 82% at the 7.5–9.5 μm range. When ZnS is coated on both sides, the transmittance is increased to approximately 90%. Our results indicate that Gd2O3 films are promising new candidates for anti-reflective coatings in the infrared region.
关键词： Rare earths,Infrared materials,Structures,Optical properties,Gadolinium oxide,Magnetron sputtering
更新于2025-09-23 15:23:52
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Photostable soft materials with tunable emission
摘要： Herein we present a synthesis of ionic liquid imidazole-based cations with appended sulfone as terminals. These structures are investigated by RMN (2D), XDR, FTIR and Raman; and show high yield; purity; melting point < 95 °C associated with thermal stability up to 239 °C; chemical stability in water and common organic solvents; and highlighted white light emission. We employed the IL as building blocks in coordination chemistry with ions Gd3+, Eu3+, and Tb3+ to elaborate translucent, luminescent and photostable soft materials. Coordination compounds were characterized by vibrational spectroscopy (FTIR/Raman), UV-vis and photoluminescence spectroscopy. Gd3+, Eu3+, Tb3+(IL)3(H2O)3 complexes display great lifetime >1.6 ms, quantum efficiency > 77%, narrow linewidth, a high degree of color purity and tunable emission. These excellent photophysical properties, associated with soft materials processability, make these materials potentially applicable in the development of luminescent films as OLEDs. We provide data for a detailed study of photoluminescence based on the theories developed by Malta-Judd-Ofelt.
关键词： europium,gadolinium,terbium,ionic liquid
更新于2025-09-23 15:22:29
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Amphiphilic nanoaggregates with bimodal MRI and optical properties exhibiting magnetic field dependent switching from positive to negative contrast enhancement
摘要： Mixed micelles based on amphiphilic gadolinium(III)-DOTA and europium(III)-DTPA complexes were synthesized and evaluated for their paramagnetic and optical properties as potential bimodal contrast agents. Amphiphilic folate molecule for targeting the folate receptor protein, which is commonly expressed on the surface of many human cancer cells, was used in the self-assembly process in order to create nanoaggregates with targeting properties. Both targeted and non-targeted nanoaggregates formed mono-disperse micelles having distribution maxima of 10 nm. The micelles show characteristic europium(III) emission with quantum yields of 2% and 1.1% for the non-targeted and targeted micelles respectively. Fluorescence microscopy using excitation at 405 nm and emission at 575-675 nm was employed to visualize nanoaggregates in cultured HeLa cells. The uptake of folate-targeted and non-targeted micelles is already visible after 5 hour incubation, and was characterized with the europium(III) emission which is clearly observable in the cytoplasm of the cells. The very fast longitudinal relaxivity r1 of ca. 26 s-1 mM-1 per gadolinium(III) ion was observed for both micelles at 60 MHz and 310 K. Upon increasing the magnetic field to 300 MHz the nanoaggregates exhibited a large switching to transversal relaxivity with r2 value of ca. 52 s-1 mM-1 at 310 K. Theoretical fitting of the 1H NMRD profiles indicate that the efficient T1 and T2 relaxations are sustained by the favorable magnetic and electron-configuration properties of the gadolinium(III) ion, rotational correlation time and coordinated water molecule. These nanoaggregates could have versatile application as a positive contrast agent at currently used magnetic imaging field strengths and a negative contrast agent in higher field applications, while at the same time offering the possibility for the loading of hydrophobic therapeutics or targeting molecules.
关键词： bimodal contrast agents,gadolinium,nanoaggregates,optical imaging,micelle,high field MRI
更新于2025-09-23 15:22:29
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Structural and optical properties of Gd+3 doped Bi2O3-GeO2 glasses and glass-ceramics
摘要： The gadolinium doped Bi2O3-GeO2 glasses and glass-ceramics have been synthesized by melt quenching and heat treatment. Structural and optical properties of prepared glasses and glass-ceramics have been examined by X-ray diffraction (XRD), Fourier transform infrared, absorption and emission measurements. XRD results have shown that the precipitated crystalline phases in glass-ceramics samples are Bi2GeO5, Bi2Ge3O9 and Bi4Ge3O12. [BiO3] and [GeO4] units are the main structural units present in Bi2O3-GeO2 glass and glass-ceramic network confirmed by IR spectra. Optical band gap values of prepared glass and glass-ceramic systems obtained from absorption spectra vary from 2.01 to 3.34 eV. The optical band gap values of glasses are larger than glass-ceramics. Bi2O3-GeO2 glass-ceramics have higher density values than glasses and densities present an increase with the elevated Gd3+ content. It is suggested that the luminescence under 366 nm excitation has been ascribed to different Bi-related emission centers. The CIE color coordinates and CCT values obtained under 366 nm excitation confirm that the Gd3+ doped bismuth germanate glasses and glass-ceramics exhibit white light emission. The most promising material for white light emitting applications within our research is found to be GC-2Gd with coordinates of (0.327, 0.314) and a CCT of 5753 K.
关键词： glass,bismuth,glass-ceramic,Gadolinium,white light,Bi2O3-GeO2
更新于2025-09-23 15:21:01
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P2653Visually Guided Laser Ablation in patients with paroxysmal and persistent atrial fibrillation - a single center experience
摘要： Predictive value of left atrial emptying fraction and late gadolinium enhancement for the clinical outcomes in atrial fibrillation patients undergoing ablation. Background: A dimension, volume and function of left atrium (LA) and late gadolinium enhancement (LGE) of the LA are known as a prognostic factor for the clinical outcome of atrial fibrillation (AF) ablation. However, which of those parameters provide a best predictive power remains unclear. Purpose: We aimed to compare the efficiency of prediction among those parameters using echocardiography and cardiac magnetic resonance (CMR). Methods: Eighty-eight consecutive patients (67 males; 56±10 years old; 45 persistent AF) underwent transthoracic echocardiography (TTE) and CMR was performed one day before AF ablation. LA anterior-posterior dimension (LAD) was measured at the phase of maximal LA size on M-mode of TTE. Maximal and minimal volume indexed to body surface area (LVAi) from CMR and Area Length Method ALM. Phasic volumes were used to calculate LA emptying fraction (LAEF) ([maximum-minimum LAV]/maximum LAVx100). LGE was defined as areas with thresholds of 6-SD above mean signal in unenhanced LV wall. The LGE stage was defined based on delayed enhancement (DE) volume area divided by LA volume (Stage 1: ≤5%, Stage 2: ≤5%, Stage 3: ≤25%, Stage 4: ≤35%). Results: During mean follow-up duration: 10±3 months, AT/AF recurred in 19/88 patients (21.5%; 3/43 in PAF; 16/45 in PeAF). Compared to patients without recurrence, those with recurrence had larger maximal/minimal LAVi (maximal: 54±21 VS. 45±16, p=0.07; minimal: 40±22 VS. 26±14, p=0.02) and LAD (45.5±6.5 VS. 40.1±5.8, p=0.001) and lower LAEF (24±10 VS. 45±16, P=0.001). ROC analysis for recurrence showed that LAEF had the largest area under curve (AUC =0.86, p=0.0001) compared to maximal LAVi, minimal LAVi and LAD. LGE stage was insignificantly higher in patients with recurrence (3.6±0.7 VS. 2.9±0.9, p=0.46). Cut-off value of LAEF for freedom from recurrence was 31.0% (sensitivity = 0.82, specificity = 0.78, p=0.001). In case of PeAF, only lower LAEF (23±11 VS. 40±7, p=0.001) and larger LAD (45.5±7.1 VS. 40.5±6.3, p=0.02) were significantly related with recurrence. Adjusting clinical risk factor, Cox-regression analysis showed that LAEF was only independent predictor for freedom from recurrence (HR = 0.88; 95% CI; 0.82–0.95; p=0.001). Conclusion: LAEF measured by CMR was superior to maximal/minimal LAVi, LAD and LGE stage in predicting the AT/AF recurrence after AF ablation. Moreover, patients with PeAF and LAEF>31% had excellent clinical outcome.
关键词： left atrial emptying fraction,ablation,atrial fibrillation,late gadolinium enhancement,clinical outcomes
更新于2025-09-23 15:19:57
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A Novel Biocompatible Titaniuma??Gadolinium Quantum Dot as a Bacterial Detecting Agent with High Antibacterial Activity
摘要： In this study, the titanium–gadolinium quantum dots (TGQDs) were novel, first of its type to be synthesized, and fully characterized to date. Multiple physical characterization includes scanning electron microscopy (SEM), scanning electrochemical microscope (SCEM), x-ray fluorescence, spectrophotometry, and dynamic light scattering were carried out. The obtained results confirmed appropriate size and shape distributions in addition to processing optical features with high quantum yield. The synthesized TGQD was used as a fluorescent dye for bacterial detection and imaging by fluorescent microscopy and spectrophotometry, where TGQD stained only bacterial cells, but not human cells. The significant antibacterial activities of the TGQDs were found against a highly pathogenic bacterium (Staphylococcus aureus) and its antibiotic resistant strains (vancomycin and methicillin resistant Staphylococcus aureus) using growth curve analysis and determination of minimum inhibitory concentration (MIC) analysis. Live/dead cell imaging assay using phase-contrast microscope was performed for further confirmation of the antibacterial activity. Cell wall disruption and release of cell content was observed to be the prime mode of action with the reduction of cellular oxygen demand (OD).
关键词： titanium–gadolinium quantum dots,bacterial resistance,antibacterial activity,bacterial detection,SECM
更新于2025-09-23 15:19:57
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Sol-Gel Synthesis and Characterization of Ba1-xGdxTiO3+δ Thin Films on SiO2/Si Substrates Using Spin-Coating Technique
摘要： Ba1-xGdxTiO3+δ, at x = 0, 0.05, 0.1, 0.15, 0.2, (BGT) thin films have been fabricated on SiO2/Si substrate using sol-gel method. The microstructure and surface morphology of the fabricated films have been investigated using X-ray diffraction (XRD) and atomic force microscopy (AFM). The XRD results show that the fabricated films are crystalline with perovskite structure. There is a shifting of the preferred peak at 31.5° to a higher angle as the doping ratio increases suggesting a distortion lattice exists in the films, which could be due to the substitution of Gd3+ ions into Ba-site. The decreasing of lattice constants confirms the substitution of Gd3+ in BaTiO3 lattice structure. The microstrain and dislocation density are found to be increased with the increase of Gd3+ doping, which attributed to the reduction of lattice volume that due to the ionic size mismatch effect. The AFM results show decreasing trend in both average grain size and roughness parameters. Therefore, the microstructure and surface morphology of BGT samples is strongly dependent on the Gd3+ doping concentration that mainly due to the difference ionic radius substitution.
关键词： microstructure,thin film,barium titanate,sol-gel,gadolinium doping
更新于2025-09-19 17:15:36
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Ammonium oxalate-assisted synthesis of Gd2O3 nanopowders
摘要： The impacts of co-precipitation reaction temperature and duration, as well as calcination temperature and duration, on the particle morphology and properties of gadolinia (Gd2O3) nanopowders were investigated. Thermogravimetric curve of thermally treated gadolinium oxalate (Gd2(C2O4)3) showed that pure stable cubic phase Gd2O3 nanopowders could be obtained by calcining at 640 °C and higher. This finding was also supported by results obtained from Fourier Transform Infrared Spectrometry (FTIR) and Raman spectrometry. This study also shows that uniform spherules of Gd2O3 nanopowders could be obtained under controlled synthesis conditions. However, with an increase in both the co-precipitation reaction temperature and duration, the extent of agglomeration of Gd2O3 nanopowders increased, as observed under a Field Emission Scanning Electron Microscope (FESEM). The FESEM images and X-ray Diffraction (XRD) patterns also revealed accelerated grain growth and increased average crystallite size at high calcination temperatures and holding times. It was determined that the most favourable Gd2O3 particle morphology was achieved when Gd2(C2O4)3 was co-precipitated at 40 °C, then thermally degraded at 650°C, for 1 h and 4 h, respectively. Estimated Scherrer’s average crystallite size of the resulting Gd2O3 nanopowders was 16.54 nm, which was further affirmed with the transmission electron microscope (TEM) image, where crystallite sizes of 3 to 27.5 nm were observed in the Gd2O3 sample. This specimen also demonstrated a considerably large specific surface area of 9.16 m2/g, as measured using a Brunauer–Emmett–Teller (BET) analyser.
关键词： Ammonium oxalate,Gadolinium oxide,Nanopowders,Co-precipitation,Gadolinia
更新于2025-09-19 17:15:36