Intensity Parameters Research Articles

Dy3+ ions in fluorophosphate glasses for luminescent white light applications

Abstract In this study, a series of fluorophosphate (FP) glasses, activated with Dy3+ ions and displaying concentration dependence, have been prepared and analysed for their suitability in luminescent white light applications. The melt quenching method was utilized to fabricate a set of FP glasses, doped with Dy3+ ions and possessing the composition of (60 − x) P2O5 + 10MgO + 10ZnO + 10BiF3 + 10KF + xDy2O3, where x ranges from 0.1 to 2.0 mol%. The structural properties of the samples were analysed using x-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), and Raman spectroscopy while the optical properties of the samples were studied using absorption and emission spectra. The amorphous nature of the FP glasses was confirmed through SEM analysis and XRD profiles. Moreover, the presence of elements in their composition was verified using EDX. The FTIR spectra of the FP glasses exhibited vibration bands consistent with the characteristic phosphate groups, which was further supported by Raman analysis. The absorption spectra were used to calculate oscillator strengths (f exp & f cal) and Judd–Ofelt (JO) parameters Ω λ (λ = 2, 4, 6). The values of Ω λ (λ = 2, 4, 6) followed this order: Ω6 > Ω2 > Ω4. The emission spectra displayed three prominent transitions in the UV–visible region: (4F9/2 → 6H15/2) blue, (4F9/2 → 6H13/2) yellow, and (4F9/2 → 6H11/2) red. The peak at 553 nm (4F9/2 → 6H13/2) was the most intense and dominant. Radiative characteristics were evaluated from the emission spectra through the employment of JO intensity parameters and refractive indices. The Y/B intensity ratio values were greater than 1, indicating the high covalency of Dy3+ ions. The colour coordinates (x, y) and correlated colour temperature values of CIE 1931 were situated in the cool white region. The comprehensive analysis suggests that these glasses have the potential to become highly favourable candidates as luminescent components for solid-state white light emitting instruments.

A Vibrotactile Belt for Measuring Vibrotactile Acuities on the Human Torso Using Coin Motors

Accurate measurement of the vibrotactile acuities of the human torso is the key to designing effective torso-worn vibrotactile displays for healthcare applications such as navigation aids for visually impaired persons. Although efforts have been made to measure vibrotactile acuities, there remains a lack of systematic studies addressing the spatial, temporal, and intensity-related aspects of vibrotactile sensitivity on the human torso. In this work, a torso-worn vibrotactile belt consisting of two crossed coin motor arrays was designed and a psychophysical study was carried out to measure the spatial, temporal, and intensity-related vibrotactile acuities of a set of human subjects wearing the designed belt. The objective parameters of vibrational intensity and the timing latency of the coin motor were also determined before measuring the vibrotactile acuities. The experimental results indicated that the tested coin motor was able to generate a median number of five and six available just-noticeable differences in intensity and duration, respectively. Among the four parameters of vibrational intensity, the perceived intensity was the most relevant to vibrational displacement. The spatial acuities measured as the degree of two-point spatial thresholds (TPTs) showed less individual difference than the distance TPTs. The results from the current work provide valuable guidance for the design of a comfortable torso-worn vibrotactile display using coin motors.

Heliospheric Effect on Solar Activity Parameters during MaximumPhase of Solar Cycle 24 (2012-2015)

Abstract The time series of daily data of solar activity proxies, namely the sunspot number (SSN), sunspot area (SSA), solar radio flux (F10.7), modified coronal index (MCI), solar flare index (FI), and cosmic ray intensity (CRI), were analyzed to understand the solar activity modulations and short-term periodicities therein. Rieger-type, and other short-term periods, including the solar rotational period that covers the maximum activity phase period (maximum phase of solar cycle 24). The wavelet power spectra and Periodogram of SSN, SSA, F10.7, MCI, FI, and CRI exhibited a significant short-term period. The heliospheric effects exist for a particular period (~27 days) and it is related to the solar activity phenomena. The cross-correlation coefficients and time lags between the cosmic ray intensity and solar activity parameters were estimated to be 200, 46, 281, 39, and 47 days for SSN, SSA, F10.7, MCI, and FI respectively during the time series 2012-2015 (maximum phase of solar cycle 24).

Investigation of Acoustic Voice Characteristics of Individuals Diagnosed with Muscle Tension Dysphonia.

Muscle tension dysphonia (MTD) is a functional voice condition that causes irregular and imbalanced laryngeal and paralaryngeal muscle activation. Our study aimed to examine the acoustic characteristics of patients with MTD and reveal the differences between genders. The study retrospectively reviewed the acoustic examination findings from the files of patients diagnosed with MTD during evaluations in the laryngology outpatient clinic at a tertiary reference hospital between 2015 and 2022. The parameters assessed in prolonged vowel phonation analysis were fundamental frequency (F0), jitter, shimmer, noise-to-harmonic-to-ratio, and soft phonation index; in the counting task analysis, they were intensity, frequency, and semitone. Gender differences in acoustic measurements obtained during prolonged vowel phonation and counting tasks were also examined. The study included 80 individuals diagnosed with MTD. Although all parameters in the acoustic analysis of/a/ phonation were increased, differences were statistically significant only in the F0 and jitter parameters between females and males (p≤0.05). In the analysis of the counting task, the mean and minimum F0 parameters were significantly higher in females than in males (p=0.000). The mean dB level was decreased, particularly in the counting task, but the results for the intensity parameter did not differ significantly between genders (p>0.05). The values in the acoustic voice analysis parameters of patients with MTD were determined. These acoustic parameters are thought to guide the clinician in evaluating voice and determining voice therapy goals for MTD patients.

Spectroscopic Properties of TmF3-Doped CaF2 Crystals.

In this study, we report the growth and comprehensive spectroscopic analysis of TmF3-doped CaF2 crystals, grown using the vertical Bridgman method. The optical absorption and photoluminescence properties of both trivalent (Tm3+) and divalent (Tm2+) thulium ions were investigated. Optical absorption spectra in the UV-VIS-NIR range reveal characteristic transitions of Tm3+ ions, as well as weaker absorption bands corresponding to Tm2+ ions. The Judd-Ofelt (JO) formalism was applied to determine the intensity parameters Ω2, Ω4, and Ω6, which were used to calculate radiative transition probabilities, branching ratios, and radiative lifetimes for the Tm3+ ions. The emission spectra showed concentration-dependent quenching effects, with significant emissions observed for the concentration of 0.1 mol% TmF3 under excitation at 260 nm and 353 nm for Tm3+ ions and at 305 nm for Tm2+ ions. A new UV emission associated with divalent Thulium is reported. The results indicate that higher TmF3 concentrations lead to increased non-radiative energy transfer, which reduces luminescence efficiency. These findings contribute to the understanding of the optical behavior of Tm-doped fluoride crystals, with implications for their application in laser technologies and radiation dosimetry.

Tuned quantum cutting efficiency by Li+/Na+ molar content in LixNa1-xGd(MoO4)2:Er3+/Yb3+ phosphors

Quantum cutting materials have garnered significant interest due to their potential applications in enhancing photoelectric conversion efficiency in devices such as solar cells. The host matrices that accommodate rare earth ions play a pivotal role in determining the optical transition properties, which are crucial for quantum cutting. In this study, both Er3+ single-doped and Er3+/Yb3+ co-doped LixNa1-xGd(MoO4)2 (x = 0, 0.01, 0.1, 0.3, 0.5, 0.7, 0.9, 0.99 and 1.0) were synthesized via a high-temperature solid-state reaction to tune the optical transitions properties and enhance quantum cutting efficiency. Optical transition intensity parameters (Judd-Ofelt parameters) of Er3+ were calculated and shown to vary significantly with the Li+/Na+ molar content, demonstrating that these optical properties can be effectively tuned by adjusting the sample composition. The reliability of these calculations was confirmed by comparing the radiative transition rate ratios between two green emissions of Er3 obtained through both theoretical and experimental methods. A two-step energy transfer mechanism was identified as the basis for quantum cutting process, and the relevant energy transfer and nonradiative relaxation rates were determined. Notably, the quantum cutting efficiency reached a peak value of 155.65 % in Li0.5Na0.5Gd(MoO4)2 sample, indicating that successful tuning of the sample's optical transition properties effectively enhanced its quantum cutting efficiency. These findings underscore the viability of tuning the optical properties of rare earth-doped materials to design highly efficient quantum cutting materials.

Analytical Overview of the Methods of Controlling the Parameters of Vibratory Compaction of the Concrete Mixes

Introduction. A historical (retrospective) overview of the evolution and application of the methods of concrete mixture compaction by vibration, as well as an overview of the breakthrough scientific+ advancements in the studied field have been presented. The use of the dry concrete mixes that reduce cement consumption, accelerate the strength gain of concrete, reduce the shrinkage strain and heat emission and increase the strength and durability of products has been proposed. The theoretical and practical issues of vibratory compaction of the concrete mixes, the research on the effect reached by the various vibration modes of the vibrating tables, the issues of choosing an efficient mode of vibration impact during compacting the concrete mixes and optimisation of their parameters have been studied. The vibrating table design, the installation layout of the vibrator’s eccentric weights to obtain a given value of the exciting force and the layout of a vibration module with the directed vibrations have been studied in detail. The criteria of duration of the concrete mixture compaction have been defined, changes of the impact parameters during compacting the concrete mixes have been characterised and technical specifications of the vibrating tables have been defined. In the article considerable attention has been paid to the main parameters of the vibrocompacting machines: frequency, amplitude and acceleration of the working member. Most often, the parameter of intensity is used to assess the efficiency of the vibration impact received by the mixture during the compaction process.Materials and Methods. A mixture that turns into concrete after compaction, setting and hardening was selected for the research. The various methods and parameters of concrete mixture compaction to obtain the high-quality concrete were studied. The impact of the various vibration modes on the process of compaction of concrete mixes was investigated, the criteria for the efficient selection and optimisation of the vibration impact parameters were revealed. The paper presents the criteria for assessing duration of the concrete mixture compaction and describes the changes in the parameters during compaction of the concrete mixes. The technical specifications of the vibrating tables of different types and sizes were also presented. The choice of the vibration compaction mode for the concrete mixture is a complicated task, which includes many parameters.Results. Upon the research, the data on the process of concrete mixture compaction under the impact of vibration forces has been obtained. The process results in the destruction of the structural bonds and weakening the bonds between the particles, which leads to the emergence of a variable stress-strain condition. It has also been found that under such settings, the mineral particles get transferred and a denser packing is formed.Discussion and Conclusion. The resulting denser packing of the concrete mixture particles ensures the undoubted economic advantage due to reduced consumption of a binder without loss of the strength properties of concrete.

Multifunctional BiOCl: Sm3+ nanophosphors: A luminescent platform for solid-state lighting applications, optical thermometry, photocatalytic and forensic applications

Rare earth-activated phosphor materials have been widely used as active probes in optical materials for multidimensional applications. Here, we report a series of ultrahigh purity orange-red emitting BiOCl: xSm3+ (x= 0.5- 2.5 mol %) nanophosphors synthesized via conventional solid-state method at relatively low temperatures for various photonic and forensic applications. XRD and Rietveld refinement results confirmed the tetragonal crystal structure of the synthesized phosphor materials with space group P4/nmm. Fourier transform infrared (FT-IR) and Raman spectroscopy were used to perform the functional group analysis. The UV-Vis-NIR spectra were analyzed to determine the Judd-Ofelt (JO) intensity parameters (Ω2, Ω4, Ω6) and to identify the bonding structure and spontaneous emission properties of the samples. The prepared phosphors exhibit intense orange-red emission under 408 nm excitation and beyond 1 mol% doping of Sm3+ ions, the emission intensity decreases due to concentration quenching mechanism via, dipole-dipole interaction between the optically active Sm3+ ions in the phosphor sample. The synthesized BiOCl: Sm3+ nanophosphors possess low correlated color temperature (CCT), admirable high color purity (99.4%) and outstanding internal quantum efficiency (IQE) of 95.27%. The optical thermometry behavior of the optimized sample has been investigated in detail. Moreover, the optimized nanophosphor stains on porous and non-porous surfaces show clear ridge patterns with high sensitivity, efficiency, and minimal background hindrance for latent fingerprints and lip print detection in forensic applications and are used as security ink in anti-counterfeiting applications. Overall, the results revealed the potential prospects of BiOCl: Sm3+ nanophosphors in the field of display applications, optical thermometry, and forensic sciences.

Spectral and Luminescence Study of Er3+ Doped Phosphate Glasses for the Development of 1.5 µm Broadband Amplifier

Ytterbium zinc lithium lead alumino antimony borophosphate glasses containing Er3+ in (25-x)P2O5: 10ZnO: 10Li2O: 10PbO: 10Al2O3: 10Sb2O3: 10Y2O3: 15B2O3: Er2O3 (where x=1, 1.5,2 mol %) have been prepared by melt-quenching method. The amorphous nature of the glasses was confirmed by x-ray diffraction studies. Optical absorption, excitation Spectrum and fluorescence spectra were recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4, 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross– section of various emission lines have been evaluated.

Photoluminescence and Raman analysis of Nd3+ doped in Ytterbium Zinc Lithium Sodium Barium Calcium Aluminophosphate glasses

Glass of the system:(30-x)P2O5:10ZnO:10Li2O:10Na2O:10BaO:10CaO:10Al2O3: 10Y2O3: x Nd2O3. (where x=1, 1.5,2 mol %) have been prepared by melt-quenching method. (where x=1,1.5 and 2 mol%) have been prepared by melt-quenching technique. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction. Optical absorption, Excitation, fluorescence and Raman spectra have been recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4 and 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross–section of various emission lines have been evaluated

Spectral, Thermal and Upconversion Properties of Dy3+ Doped Borotellurite Glasses with Large Stability Parameter

Glass sample of yttrium zinc lithium lead sodium alumino borotellurite (25-x) TeO2:10ZnO:10Li2O:10PbO:10Na2O:10Al2O3:10Y2O3:15B2O3:xDy2O3. (wherex=1,1.5 and 2 mol%) have been prepared by melt-quenching technique. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction. Optical absorption, excitation spectrum and fluorescence spectra were recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4 and 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross–section of various emission lines have been evaluated

Genetic parameters for methane production, intensity, and yield predicted from milk mid-infrared spectra throughout lactation in Holstein dairy cows

Genetic selection to reduce methane (CH4) emissions is a promising solution for reducing the environmental impact of dairy cattle production. Before such a selection program can be implemented, however, it is necessary to have a better understanding of the genetic determinism of CH4 emissions and how this might influence other traits of interest. In this study, we performed a genetic analysis of 6 CH4 traits predicted from milk mid-infrared spectra. We predicted 4 CH4 traits in g/d (MeP, calculated using different prediction equations), one in g/kg of fat- and protein-corrected milk (MeI), and one in g/kg of dry matter intake (MeY). Using an external data set, we determined these prediction equations to be applicable in the range of 70 to 200 DIM. We then estimated genetic parameters in this DIM range using random regression models on a large data set of 829,025 spectra collected between January 2013 and February 2023 from 167,514 first- and second-parity Holstein cows. The 6 CH4 traits were found to be genetically stable throughout and across lactations, with average genetic correlations within a lactation ranging from 0.93 to 0.98, and those between lactations ranging from 0.92 to 0.98. All 6 CH4 traits were also found to be heritable, with average heritability ranging from 0.24 to 0.45. The average pairwise genetic correlations between the 6 CH4 traits ranged from -0.15 to 0.77, revealing that they are genetically distinct, including the 4 measurements of MeP. Of the 6 traits, 2 measures of MeP and MeI did not present antagonistic genetic correlations with milk yield, fat and protein contents, and SCS, and can probably be included in breeding goals with limited impact on other traits of interest.

Validation of an algorithm that separates gaseous micro-embolic signals and artifacts during transcranial Doppler persistent foramen ovale examinations

ObjectivePersistent foramen ovale (PFO) is a risk factor for young stroke. Agitated saline serum is used to deliver small gaseous emboli to the brain in transcranial Doppler ultrasound (TCD) for the detection and grading of PFO. In this study we validated a PFO algorithm that can differentiate between gaseous emboli and artifacts. MethodsThe validation cohort comprised 18 patients with positive PFO examinations. The PFO algorithm uses a binary tree that separates high-intensity transients signals (HITs) into gaseous emboli or artifacts based on intensity, zero-crossing, and velocity parameters. ResultsThe cohort exhibited 385 macroscopic gaseous emboli meeting the >3 dB criterion. An additional 137 gaseous emboli were noticed below the 3-dB intensity cutoff value. The low-intensity gaseous emboli included both macroscopic and microscopic air bubbles observed in curtains. Nearly all emboli (98 %) above the 3-dB level showed overt frequency modulation. The overall accuracy of the PFO algorithm in discriminating macroscopic gaseous emboli and artifacts was 96.4 %, with a similar percentage of sensitivity and specificity (96.4 %). The inter-observer agreement of human experts was excellent (ic-CC 0.989 and 0.953). ConclusionsMacroscopic gaseous emboli and artifacts during PFO exams can be accurately discriminated by the PFO algorithm. The PFO algorithm cannot be used as a standalone system as microscopic air bubbles might escape proper identification. This knowledge will be important in the design of future PFO algorithms which should make it possible to classify the PFO grade without the interference of humans.

Temperature dependence of Ce luminescence characteristics in LaBr3: Ce crystal

Despite the large interest in the scintillation properties of LaBr3:Ce, a detailed understanding of the underlying mechanism of temperature-dependence properties of Ce luminescence remains elusive. This study introduces a self-designed spectral apparatus to explore these properties in LaBr3:5%Ce. We observed a redshift phenomenon and band changes in the emission peak bands, indicating a reduction of the bond length between Ce and the host with increasing temperature. Moreover, the probability of low-energy peak emission decreases and the probability of high-energy peak emission increases, with increasing temperature was observed, suggesting a correlation with the proximity of Ce's 4f energy level to the valence band. Utilizing intensity parameters from the spectra, we identified the impact of temperature on LaBr3:Ce's self-absorption effect, revealing a significant self-absorption effect at the high-energy peak for the first time. A simple self-absorption model indicated that, despite high quantum efficiency of Ce, the overall self-absorption is minimal, establishing a correlation between the self-absorption coefficient of the high-energy peak and overall absorption. This research offers insights for developing radiation-resistant high-temperature luminescent devices and advances the field of high-temperature luminescent materials.

An extensive inquisition on the impact of modifier oxides over the luminescent properties of Eu3+ embedded Li-Al tri-former glasses for photonic applications

A novel, tri-former glasses with the composition 45B2O3+12P2O5+8SiO2+3Al2O3+10LiF+20MO+1Eu2O3 with varying metal oxides have been fabricated following the melt-quenching technique. The absorption, luminescence and radiative decay measurements were carried out, and the specific colour emitted by the glass sample was determined employing the CIE chromaticity diagram. While monitoring the excitation at 393 nm, luminescence spectra of all the glass samples exhibit red emission pertaining to the 5D0→7F2 transition at around 615 nm. The local geometry around the Eu3+ ions site and the nature of the Rare Earth ion-ligand bond have been analyzed employing Judd-Ofelt theory and the R/O ratio spectral parameter. The intensity parameters follows the trend as Ω2 > Ω4 > Ω6 and the results are co-related well with the R/O ratio spectral parameter values. Radiative properties such as σPE, βR and AR of every glass in the present series possess higher values, and the FWHM exhibits lower value, indicating the potentiality of the BPSAEu:M glasses for lasing applications. Among the prepared samples, BPSAEu:Ba glass exhibit higher values for σPE and AR as 42.3 × 10−22 cm2 and 641.71 s−1 respectively which are apt for laser applications. The quantum yield pertaining to the 5D0→7F2 transition exhibit more than 65 % for all the samples and particularly Barium oxide incorporated glass BPSAEu:Ba exhibits 84 %. The present study suggests that BPASEu:Ba glass is a promising luminescent material for photonic/LED applications.

Assessment of luminescent features on Sm3+ ions doped LiF assimilated lead-free borate glasses for visible photonic and optoelectronic applications

The distinctive set containing Sm3+ ions doped LiF incorporated Alkaline borate glasses have been synthesised via the melt quenching practice. 59B2O3+20LiF+(20–X)CaCO3+XBaCO3 +1Sm2O3 (where X = 5, 10, 15, 20 wt%) is the composition used for the glass preparation. The effect of samarium ions concentration dependency on the absorption and emission of barium and calcium oxide has been studied through several spectroscopic studies. The current set of glasses is ionic, determined by the bonding value. The hypersensitive absorption transition is found in the visible region of the absorption spectra, and the transition from 6H5/2 to 6P3/2 shows the highest oscillator strength of 14.87 × 10−6. The intensity parameters are denoted by Ωλ (where λ = 2,4,6) are assessed and discussed. The results indicate that Ω4 is higher when compared to the other two parameters. The lower Ω2 values further ensure the ionic nature of the glass samples. Moreover, the intensity parameters are utilised to predict some radiative properties for the lasing potential evaluation, which includes cross-sections of emission (σPE), probability of radiative transition (A), and experimental and radiative lifetime (τexp and τR). The decay profile was monitored for the 4G5/2 state, and consistently non-exponential behaviour was observed in all the glasses. Through the CIE colour chromaticity analysis, the CCT (colour-correlated temperature), dominant wavelength, colour, and purity of the emitted light have been evaluated. Concerning all aspects, the glass with 20 wt% of BaCO3 is found to be fit for photonic and optoelectronic applications.

Liver function assessment based on hepatobiliary contrast agent-enhanced magnetic resonance imaging

BACKGROUND: Liver function assessment is very important in clinical practice. The use of magnetic resonance imaging for the anatomical and functional evaluation of the liver is possible in actual clinical practice. AIM: To examine the possibility of using hepatobiliary contrast-enhanced magnetic resonance imaging for the evaluation of liver function. MATERIALS AND METHODS: Datasets of patients who underwent gadoxetic acid-enhanced magnetic resonance imaging were retrospectively reviewed. Patients were divided into two groups: group 1 included patients with impaired liver function, and group 2 included those with normal liver function. Based on magnetic resonance imaging in the hepatobiliary phase, the liver parenchyma signal intensity and its ratio to spleen signal intensity and portal vein signal intensity were estimated. Differences among these parameters were compared between groups. The correlation between liver parenchyma signal intensity and laboratory blood tests reflecting liver function (total bilirubin, albumen, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma glutamyl transpeptidase, and prothrombin time) were analyzed. RESULTS: Datasets of 53 patients (25 men and 28 women, aged 24–84 years) were analyzed. Group 1 included 19 patients, whereas group 2 included 34. The median liver parenchyma signal intensity was 919.05 [669.65; 1258.35] in group 1 and 1525.13 [1460.5; 1631.4] in group 2 (p=0.0000001). The median ratio of liver parenchyma signal intensity to spleen signal intensity was 1.2 [1.04;1.7] in group 1 and 1.7 [1.46; 1.96] in group 2 (p=0.00076). The median ratio of liver parenchyma signal intensity to portal vein signal intensity was 1.44 [1.29; 1.83] in group 1 and 1.6 [1.43; 1.83] in group 2 (p=0.1). The estimated correlation values between liver parenchyma signal intensity and blood tests parameters were as follows: total bilirubin (r=–0.61; p=0.000001), albumen (r=0.13; p=0.61), aspartate aminotransferase (r=–0.57; p=0.000009), alanine aminotransferase (r=–0.44; p=0.001), alkaline phosphatase (r=–0.45; p=0.0007), gamma glutamyl transpeptidase (r=–0.5; p=0.0003), prothrombin time (r=–0.34; p=0.04). CONCLUSION: The study reflects the ability to assess liver function using indices (liver parenchyma signal intensity and its ratio to spleen signal intensity) derived from gadoxetic acid-enhanced magnetic resonance imaging. However, this study did not confirm the assumed effectiveness of using the liver parenchyma signal intensity to portal vein signal intensity ratio as an index of liver function. A significant inverse correlation was identified between liver parenchyma signal intensity and blood test parameters in reflecting liver function, except for albumin. The results indicate the possibility of using magnetic resonance imaging to assess liver function.

In Search of Covalency Measure of Gd(III)-Ligand Interactions.

Experimental electron density distribution of the [C(NH2)3]3[Gd(EDTA)F2]·H2O crystal was determined. The derived experimental and theoretical (DFT) topological parameters such as ∇2ρc, ρc, bond degree (BD), kinetics, and potential energy were used to study the nature of Gd-O, Gd-F, and Gd-N interactions. The natural charge of the Gd is 1.86; the natural configuration of the cation is [Xe]6s0.134f7.105d0.83, and the covalency of the Gd-L bond is mainly connected with the transfer of charge from the spx ligand orbitals onto the 5d orbitals of the Gd cation. Simultaneously, the donation of charge onto the 6s and 4f orbitals occurs to a lesser extent. Moreover it was found that the donation of the ligand charges onto the Gd(III) is larger for compounds with a lower coordination number. The obtained topological parameters were analyzed in the context of the Gd(III) f-f transition properties, i.e., energy of the excited 2S+1LJ states, Judd-Ofelt intensity parameters, and luminescence lifetimes, of 18 Gd(III) compounds with various O, N, and F donor ligands (DOTA, EDTA, CDTA, DTPA, NTA, EGTA, ODA, F-, H2O, and CO32-). The calculated nephelauxetic β parameter may reflect the penetration degree of electron lone pairs of ligands inside the metal basin. Finally, it was found for the first time that the sum of the Gd(III)-L bond energy (∑EGdL) is correlated with the position of the gravity center of the 8S7/2 → 2S+1LJ transitions and increase of covalency of the Gd(III)-L bonds is associated with decrease of their bond energy. The obtained results may shed light on chemical bonding in systems containing f-elements. Such subtle differences in the covalent contribution to the Ln-L or An-L bond may tune the selectivity of the partitioning processes of lanthanides and actinides.

Analysis of spectroscopic characteristics of Sm3+ ions doped gallium silicate glasses for orange-red LEDs

In this work, a variety of Sm3+ ions doped gallium silicate glasses have been made using the conventional melt quenching procedure, and characterized by X-ray diffraction, absorption spectrum, fluorescence spectrum, fluorescence decay curves, respectively. The density of the glass increases with the increase of the concentration of Sm3+ ions, and XRD shows that the samples are all amorphous glasses. Absorption spectra were used to determine the J-O intensity parameters (Ωλ, λ = 2, 4, 6), as well as the radiation transition probability(A), fluorescence branching ratio(βr), and radiation lifetime(τr) of Sm3+ ions at the 4G5/2 energy level. Under 403 nm excitation, the emission spectra show obvious emission peaks at 602 nm and 649 nm, corresponding to 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 transitions respectively. The B3 glass sample has the largest emission cross section(σem) at the 4G5/2 → 6H7/2 transition, with σem = 11.40 × 10−22 cm2. The color coordinates, color purity and color temperature values of all samples were calculated. The color purity of all samples varied in the range of 96.20%–99.14 %, with the relevant samples separating in the orange-red light region. The experimental results indicate that the glass samples have a potential application prospect in the field of orange-red LEDs.

Spectroscopic analysis of La2(WO4)3:Tb3+ phosphor and the delayed concentration quenching of 5D4 →7FJ emission

Trivalent terbium ion doped lanthanum tungstate (La2-xTbx(WO4)3; x = 0.6,1.0,1.4) and terbium tungstate (Tb2(WO4)3) phosphors were successfully synthesized via optimized microwave-assisted co-precipitation technique. The phase purity and crystallinity of the prepared samples were confirmed using the powder XRD technique. The photoluminescence studies revealed a quenching-free emission up to 70 % of Tb3+ doping concentration, even though the emission intensity slightly decreases under host excitation since it becomes less relevant at higher doping concentrations. The experimental and calculated oscillator strengths were evaluated using absorption data and further used to quantify the Judd - Ofelt (JO) intensity parameters, which appeared in a trend of Ω2>Ω4>Ω6 for all samples. As a theoretical approach to assure the excellency of the tungstate host, the radiative parameters were calculated from the emission data using the JO analysis technique. The dominance in the values of stimulated emission cross section and gain bandwidth corresponding to 5D4→7F5 transition of Tb3+ ion of lanthanum tungstate proclaims it as an excellent green phosphor. Hence, the less susceptibility of the tungstate host towards concentration quenching is confirmed in the present work.