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Utilizing metal nanoprobes with unique K-edge identities to visualize complementary biological activities simultaneously can provide valuable information about complex biological processes. This study describes the design and preparation of an innovative pair of K-edge metal nanoprobes and demonstrates the feasibility of their simultaneous quantitative detection using spectral photon-counting computed tomography (SPCCT). Glycosaminoglycan (GAG) capped nanoparticles (ca. 15-20 nm) targeting two distinct components of the cartilage tissue, namely, aggrecan (acan) and aggrecanase (acanase) are designed and synthesized. These targeted nanoparticles comprised of praseodymium (Pr) and hafnium (Hf), with well-separated K-edge energies, enable simultaneous and ratiometric imaging of dual biomarkers in cartilage tissue. Following extensive physico-chemical characterization of the ligand-targeted particles, the feasibility of homing dual biomarkers in vitro is demonstrated. The material discrimination and simultaneous quantification of these targeted particles are also achieved and corroborated with inductively coupled plasmon spectroscopy. For the first time, the use of praseodymium is reported as a contrast agent for SPCCT imaging and demonstrates the ability to pair it with hafnium nanoprobes for multicontrast imaging of diseases. Importantly, the potential for ratiometric molecular imaging and tracking of osteoarthritis (OA) progression is shown with SPCCT K-edge based imaging approach., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

A microtubule ultrafiltration reactor (MUFR), with an organophosphorus system containing a sewage section with buffer liquid acetic acid and an enrichment section with aqua fortis liquid and organophosphorus dissolved in fuel oil, has been studied for praseodymium(III) migration. Many factors of praseodymium(III) migration using MUFR need to be explored, including hydrogen ion molarity (or pH), cinit of praseodymium(III), the different ionic strengths of rare-earth mine sewage, the volume ratio of organophosphorus fuel oil and aqua fortis liquid (O/A), aqua fortis' molarity, organophosphorus' molarity, and the effects of different acid liquids in the enrichment section on praseodymium(III) migration with MUFR. The virtues of MUFR compared to conventional migration were explored. The effects of the hydrodynamic properties (stability and flow velocity) and UF system parameters (internal diameter of the microtubule, tubule shell thickness, void ratio), etc., on the mass migration performance of the MUFR process for praseodymium(III) migration were also studied. The experimental results show that the best migration prerequisites of praseodymium(III) were obtained as follows: an aqua fortis molarity of 4.00 mol/L, an organophosphorus molarity of 0.200 mol/L, an O/A of 0.6 in the enrichment section, and a pH value of 4.80 in the sewage section. The ionic strength of rare-earth mine sewage had no obvious effect on praseodymium(III) migration. When the cinit of praseodymium(III) molarity was 1.58 × 10 -4 mol/L, the migration percentage of praseodymium(III) reached 95.2% in 160 min.

The current study explores development of highly vascularizable biomatrix scaffold containing rare-earth metal praseodymium oxide nanoadditives for angiogenic and soft tissue regenerative applications. The therapeutic potential of praseodymium oxide nanoparticles rendered excellent endothelial cell differentiation for inducing pro angiogenic microenvironment by eliciting VE-Cadherin expression in the biomatrix scaffold. The nanoparticles were incorporated into bio-macromolecule collagen which aided in stabilization of collagen by maintaining the structural integrity of collagen and showed less susceptibility towards protease enzymes, high cyto-compatibility and high hemo-compatibility. The scaffold provided 3-dimensional micro-environments for the proliferation of endothelial cells and fibroblast cells promoting the wound healing process in an orchestrated fashion. Biological signal modulatory property of rare earth metal is the unexplored domains that can essentially bring significant therapeutic advancement in engineering advanced biological materials. This study opens potential use of nano-scaled rare earth metals in biomaterial application for tissue regeneration by modulating the pro-angiogenesis and anti-proteolysis properties., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Apart from perovskites, the development of different types of pyrochlore oxides is highly focused on various electrochemical applications in recent times. Based on this, we have synthesized pyrochlore-type praseodymium stannate nanoparticles (Pr 2 Sn 2 O 7 NPs) by using a coprecipitation method and further investigated by different analytical and spectroscopic techniques such as X-ray diffraction, Raman spectroscopy, field emission-scanning electron microscopy, high resolution-transmission electron microscopy, and X-ray photoelectron spectroscopy analysis. Followed by this, we have designed a unique and novel electrochemical sensor for nitrofurazone detection, by modifying the glassy carbon electrode (GCE) with the prepared Pr 2 Sn 2 O 7 NPs. For that, the electrochemical experiments were performed by using cyclic voltammetry and differential pulse voltammetry techniques. The Pr 2 Sn 2 O 7 NPs modified GCE exhibits high sensitivity (2.11 μA μM -1 cm -2 ), selectivity, dynamic linear ranges (0.01-24 μM and 32-332 μM), and lower detection limit (4 nM). Furthermore, the Pr 2 Sn 2 O 7 NPs demonstrated promising real sample analysis with good recovery results in biological samples (human urine and blood serum) which showed better results than the noble metal catalysts. Based on these results, the present work gives clear evidence that the pyrochlore oxides are highly suitable electrode materials for performing outstanding catalytic activity toward electrochemical sensors.

A novel strategy is proposed based on the efficient energy transfer from Tb 3+ to Pr 3+ for the sensitive and selective discrimination of praseodymium ions due to the matched energy levels of 5 D 4 (Tb 3+ ) and 3 P 0 (Pr 3+ ). The electron of Tb 3+ transfers from the ground state to the excited state under the excitation of ultraviolet light and relaxes to the  5 D 4 level. In the presence of Pr 3+  the electron has no time to return to the ground state, thus it transfers to the 3 P 0 level of Pr 3+  resulting in the quenching of Tb 3+ luminescence. In the case of GdPO 4 : Tb 3+ nanowire, its fluorescence intensity at 545 nm linearly decreased when Pr 3+ concentration ranged from 1 × 10 -7 to 1 × 10 -5  M, and the detection limit was 75 nM. To further investigate the sensing mechanism, CePO 4 : Tb 3+ , YPO 4 : Tb 3+ , and YBO 3 : Tb 3+ nanoparticles were also synthesized for Pr 3+ ion detection. For all materials, similar fluorescence quenching by Pr 3+ ions occurred, which confirmed the efficient energy transfer from Tb 3+ to Pr 3+ ions. Utilizing the matched energy levels of 5 D 4 (Tb 3+ ) and 3 P 0 (Pr 3+ ), for the first time, we proposed a novel strategy (taking GdPO 4 : Tb 3+ probe as the example) based on the efficient energy transfer from Tb 3+ to Pr 3+ for the sensitive and selective discrimination of praseodymium ions.

The antioxidant activity of ceria nanoparticles is tightly regulated by size distribution and heteroatom doping. Inspired by this rule, cerium and praseodymium codoped carbon quantum dots (Ce/Pr-CQDs) were synthesized through the one-pot hydrothermal carbonization method. Taking intrinsic advantage of CQDs, the resultant Ce/Pr-CQDs exhibited uniform and ultra-small morphology with an average size of 2.8 nm, which led to an increased proportion of Ce 3+ . In addition, the doping of Pr into Ce-CQDs improved the redox properties. As we expected, the Ce/Pr-CQDs possessed enhanced hydroxyl radical scavenging properties compared with the cerium-doped carbon quantum dots (Ce-CQDs). Furthermore, Ce/Pr-CQDs with favorable biocompatibility and negligible cytotoxicity are readily internalized into cytoplasm, decreasing the level of reactive oxygen species (ROS). Taken together, the resultant Ce/Pr-CQDs displayed great potential for applications relating to oxidative-stress-associated disease.

In this work, we successfully developed a novel and sensitive gas sensor for the determination of trace acetophenone based on its cataluminescence (CTL) emission on the surface of nano-praseodymium oxide (nano-Pr 6 O 11 ). The effects of working conditions such as temperature, flow rate, and detecting wavelength on the CTL sensing were investigated in detail. Under the optimized conditions, the sensor exhibited linear response to the acetophenone in the range of 15-280 mg/m 3 (2.8-52 ppm), with a correlation coefficient ( R 2 ) of 0.9968 and a limit of detection (S/N = 3) of 4 mg/m 3 (0.7 ppm). The selectivity of the sensor was also investigated, no or weak response to other compounds, such as alcohols (methanol, ethanol, n -propanol, iso -propanol, n -butanol), aldehyde (formaldehyde and acetaldehyde), benzenes (toluene, o -xylene, m -xylene, p -xylene), n -pentane, ethyl acetate, ammonia, carbon monoxide, carbon dioxide. Finally, the present sensor was applied to the determination of acetophenone in human exhaled breath samples. The results showed that the sensor has promising application in clinical breath analysis.

In a facile synthesis, highly colloidal, bioactive Pr(OH) 3 -encapsulated silica microspheres (PSMSs) with an average diameter of 500-700 nm were successfully prepared via a sol-gel process followed by heat treatment. The phase formation, morphology, surface and optical properties of the as-synthesized PSMSs were characterized by various techniques including X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), N 2 -adsorption-desorption, energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR) and UV/vis spectroscopy. The PSMSs were semi-amorphous or ultra-small in size, highly dispersible in water, mesoporous, irregular in size and spherical in shape. The SEM images show a well-ordered broad nanoporous structure which is preserved after coating with Pr(OH) 3 molecules, demonstrating interaction between the optically active Pr 3+ ion and silanol (Si-OH) groups via hydrogen bonding. Optical spectra show well-resolved weak intensity 4f-4f absorption transitions in the visible region of the Pr 3+ ion, indicating successful grafting of the Pr(OH) 3 layer. Toxicity was measured by MTT and NRU assays to determine potential toxicity. Cell viability was suppressed with increasing dosage of PSMSs, but showed greater than 55% cell viability at a concentration of 200 μg/mL, resulting in low toxicity. Due to its high aqueous dispersibility, optical activity, excellent biocompatibility and low toxic nature, it could be a favorable material for biomedical and drug delivery applications., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this study, fluorescence emission spectra, UV-vis absorption spectra, ethidium bromide (EB)-competition experiment, and iodide quenching experiment were used for the interaction study of the Fish salmon DNA (FS-DNA) with [Pr(dmp)2Cl3(OH2)] where dmp is 2,9-dimethyl 1,10-phenanthroline. The binding constant and the number of binding sites of the complex with FS-DNA were 6.09 ± 0.04 M -1 and 1.18, respectively. The free energy, enthalpy, and entropy changes (ΔG°, ΔH°, and ΔS°) in the binding process of the Pr(III) complex with FS-DNA were -8.02 kcal mol -1 , +39.44 kcal mol - 1, and +159.56 cal mol -1 K -1 , respectively. Based on these results, the interaction process between FS-DNA with [Pr(dmp)2Cl3(OH2)] was spontaneous and the main binding interaction force was groove binding mode. Also, Fluorescence and electronic absorption spectroscopy were used in order to evaluate the binding characteristics, stoichiometry, and interaction mode of praseodymium(III) (Pr(III)) complex with bovine serum albumin (BSA). Title complex showed good binding propensity to BSA presenting moderately high Kb values. The fluorescence quenching of BSA by Pr(III) complex has been observed to be the static process. The positive ΔH° and ΔS° values showed that the hydrophobic interaction is the main force in the binding of Pr(III) complex and BSA. Eventually, the average aggregation number, , of BSA potentially induced by title complex confirmed the 1:1 stoichiometry for title complex-BSA adducts. In vitro, antimicrobial activity of title complex was indicated that the complex is more active against both Escherichia coli and Enterococcus faecalis bacterial strains than Staphylococcus aureus, and Pseudomonas aeruginosa. Communicated by Ramaswamy H. Sarma.

The emission of nitrogen oxides has caused severe harm to the ecosystem; thus, the development of low-cost and high-efficiency denitrification catalysts and new methods are of great significance. In this work, a co-precipitation method was employed to prepare Pr-doped CeO 2 /attapulgite (CeO 2 /Pr 3+ /ATP) nanocomposites. X-ray diffraction (XRD), photoluminance spectroscopy (PL), ultraviolet-visible diffuse reflectance (UV-Vis), Fourier transform infrared (FT-IR), and high-resolution transmission electron microscopy (HRTEM) were utilized to characterize the products. Results showed that the CeO 2 /Pr 3+ nanoparticles were uniformly coated on the surface of ATP and demonstrated outstanding upconversion effect which converted the visible light to ultraviolet light. The upconversion luminescence of CeO 2 /Pr 3+ /ATP was strongest when the molar doping amount of Pr was 1 mol%, and the photo-SCR denitrification achieved the highest of 90% conversion and 95% selectivity when the loading amount of CeO 2 /Pr 3+ was 40 wt%. The ATP and CeO 2 /Pr 3+ constructed an indirect Z-type heterojunction structure mediated by oxygen vacancy which benefited the separation of charge carriers and enhanced the reduction-oxidation potentials, both are responsible for the remarkable denitrification performance.

The analytical quantification and follow-up of the hormone prolactin is very important in clinical diagnosis (e.g., in cases of breast cancer), treatment, and the medical laboratory. The development of a new simple, fast, and less costly method is of considerable importance. Novel praseodymium metal-organic framework nanofibers (Pr-MOF-NFs) were synthesized by a facile and simple method for the determination of human prolactin in serum samples. The Pr-MOF-NFs were well characterized with several spectroscopic tools, such as mass spectrometry, Fourier transform IR spectroscopy, UV-vis spectroscopy, elemental analysis, X-ray diffraction, field-emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. The photoluminescence of Pr-MOF-NFs was investigated, and the results revealed that Pr-MOF-NFs could be used as a sensitive and selective nanofiber optical sensor for the detection of human prolactin. The calibration graph was studied over a wide prolactin concentration range of 0-200 ng/mL, with limits of detection and quantitation of 0.276 and 0.838 ng/mL, respectively, lower than the values mentioned in previous reports. The correlation coefficient was 0.9792. Moreover, the Pr-MOF-NFs were applied successfully for the detection of serum human prolactin at clinically applicable concentrations without interference from several types of hormones and various interfering analytes. Graphical abstract.

BaGd 2 O 4 :Eu 3+ scintillating phosphors by Pr 3+ -codoping were synthesized at 1300°C in air using a solid-state reaction method. The as-synthesized phosphors were characterized by X-ray diffraction (XRD), photoluminescence (PL) including excitation and emission spectra, radioluminescence (RL) spectra excited by X-ray and thermoluminescence (TL) spectra. Both the PL and RL spectra are composed of the featured trivalent europium (Eu 3+ ) without any praseodymium (Pr 3+ ) ions, and the PL and RL intensities as well as the lifetimes of BaGd 2 O 4 :Eu 3+ scintillating phosphors decrease dramatically with an increasing concentration of Pr 3+ ions. Finally, the TL spectra reveal the trap concentration of the existing defects decrease with an increasing concentration of Pr 3+ ions, while the relative TL intensity ratio of the high temperature band to the low temperature one increases with an increasing concentration of Pr 3+ ions, which results in the afterglow suppression of BaGd 2 O 4 :Eu 3+ scintillating phosphors., (© 2018 John Wiley & Sons, Ltd.)

The lanthanide ion praseodymium, Pr(III), was employed to study metallated ion formation and electron transfer dissociation (ETD) of 27 biological and model highly acidic phosphopeptides. All phosphopeptides investigated form metallated ions by electrospray ionization (ESI) that can be studied by ETD to yield abundant sequence information. The ions formed are [M + Pr - H] 2+ , [M + Pr] 3+ , and [M + Pr + H] 4+ . All biological phosphopeptides with a chain length of seven or more residues generate [M + Pr] 3+ . For biological phosphopeptides, [M + Pr] 3+ undergoes more backbone cleavage by ETD than [M + Pr - H] 2+ and, in some cases, full sequence coverage occurs. Acidic model phosphorylated hexa-peptides and octa-peptides, composed of alanine residues and one phosphorylated residue, form exclusively [M + Pr - H] 2+ by ESI. Limited sequence information is obtained by ETD of [M + Pr - H] 2+ with only metallated product ions being generated. For two biological phosphopeptides, [M + Pr + H] 4+ is observed and may be due to the presence of at least one residue with a highly basic side chain that facilitates the addition of an extra proton. For the model phosphopeptides, more sequence coverage occurs when the phosphorylated residue is in the middle of the sequence than at either the N- or C-terminus. ETD of the metallated precursor ions formed by ESI generates exclusively metallated and nonmetallated c- and z-ions for the biological phosphopeptides, while metallated c-ions, z-ions, and a few y-ions form for the model phosphopeptides. Most of the product ions contain the phosphorylated residue indicating that the metal ion binds predominantly at the deprotonated phosphate group. The results of this study indicate that ETD is a promising tool for sequencing highly acidic phosphorylated peptides by metal adduction with Pr (III) and, by extension, all nonradioactive lanthanide metal ions., (© 2018 John Wiley & Sons, Ltd.)

The luminescence properties of praseodymium (Pr 3+ ) ion in potassium bromide (KBr) host have been investigated. The excitation bands observed in the region 220-300 nm are attributed to the transitions from 4f level to the 5d crystal field splitting levels of Pr 3+ ion. Emission bands originated due to transition of 3 P 2 → 3 H 6 (564 nm), 3 P 0 → 3 H 6 (604 nm), 1 D 2 → 3 P 4 (721 nm) and 3 P 0 → 3 F 2 (659 nm) have been observed. Optical absorption, photoluminescence (PL) and thermoluminescence (TL) studies confirms the trivalent state of Pr 3+ ion in KBr host. Trap parameters for the TL glow curve have been calculated and the values are tabulated by using Chen's peak shape method. The lattice cell parameters of Pr 3+ doped KBr single crystals are a = b = c = 6.596 Å, α = β = γ = 90°. From the scanning electron microscopy (SEM) micrograph analysis, the particle size ranges from a few micrometres to 5 μm. Electron paramagnetic resonance (EPR) spectrum exhibits two resonance signals at magnetic fields of 2895 and 3106 gauss with g-values of 2.32 and 2.16, respectively, calculated using Lande's formula., (Copyright © 2018 John Wiley & Sons, Ltd.)

The high demand for rare earth elements (REEs) used in various advanced materials implies demand for increased production of REEs or the recycling of solutions to recover the REEs they contain. In this study, the biosorption of Pr(III) from aqueous solution by bark powder of Terminalia arjuna was examined in a batch system as a function of metal concentration, biosorbent dosage, pH and contact time. Results showed that T. arjuna bark powder has a high affinity for adsorbing Pr(III): more than 90% at pH 6.63. The adsorption of Pr(III) by T. arjuna bark powder was investigated by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The kinetics of the biosorption process was tested with pseudo-first-order and pseudo-second-order models, and the results showed that the biosorption process was better fitted to the pseudo-second-order model. From Fourier transform infrared spectroscopy (FT-IR) analysis, it is confirmed that the biomolecules of T. arjuna bark powder are involved in the biosorption process of Pr(III) metal ions.

Modified synthesis and luminescence of Y 2 BaZnO 5 phosphors activated with the rare earths (RE) Eu 3 + , Tb 3 + , Pr 3 + and Sm 3 + are reported. RE 2 BaZnO 5 phosphors have attracted attention because of their interesting magnetic and optical properties; and are usually prepared using a two-step solid-state reaction. In the first step, carbonates or similar precursors are thoroughly mixed and heated at 900°C to decompose them to oxides. To eliminate the unwanted phases like BaRE 2 O 4 , the resulting powders are reheated at 1100°C for a long time. We prepared Y 2 BaZnO 5 phosphors activated with various activators by replacing the first step with combustion synthesis. The photoluminescence results are presented. The photoluminescence results for Eu 3 + , Tb 3 + and Pr 3 + are in good agreement with the literature. However, photoluminescence emission from Sm 3 + has not been documented previously. The excitation spectrum of Eu 3 + is dominated by a charge transfer band around 261 nm, and an additional band around 238 nm is always present, irrespective of the type of activator. The presence of this band for all these different types of activators was interpreted as host absorption., (Copyright © 2016 John Wiley & Sons, Ltd.)

The red-emitting phosphor Ca 0.8 Zn 0.2 TiO 3 :Pr 3+ was synthesized using an ethylene glycol (EG)-assisted hydrothermal method. The effects of additional amounts of and order of adding EG, plus hydrothermal temperature, time, and pH on the composition, morphology and optical properties of the titanate phosphors were studied. The crystalline phases of the titanate phosphors were confirmed to be constituted of a series of co-existing CaTiO 3 , Zn 2 TiO 4 and Ca 2 Zn 4 Ti 16 O 38 compounds in various proportions that were visualized using an X-ray diffractometer (XRD). The optical properties of the phosphors were studied using photoluminescence spectra and UV-visible spectroscopy. The results show that the impurities Zn 2 TiO 4 :Pr 3+ and Ca 2 Zn 4 Ti 16 O 38 :Pr 3+ significantly contributed to the enhancement of an absorption band around 380 nm. The optimum Ca 0.8 Zn 0.2 TiO 3 :Pr 3+ phosphor consisting of appropriate amounts of CaTiO 3 , Ca 2 Zn 4 Ti 16 O 38 and Zn 2 TiO 4 in three phases was achieved by controlling the hydrothermal conditions, and the obtained red phosphor exhibited the highest red emission ( 1 D 2  →  3 H 4 transition of Pr 3+ ) with an ideal chromaticity coordinate located at (x = 0.667, y = 0.332) under 380 nm excitation., (Copyright © 2017 John Wiley & Sons, Ltd.)

The identification of major uptake pathways in plants is an important factor when evaluating the fate of manufactured nanoparticles in the environment and the associated risks. Using different radiolabeling techniques we were able to show a predominantly particulate uptake for CeO 2 nanoparticles in contrast to a possible uptake in the form of ionic cerium., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ceria nanocubes (NC) modified with increasing concentrations of praseodymium (5, 10, 15, and 20 mol %) have been successfully synthesized by a hydrothermal method. The as-synthesized Pr-modified ceria nanocubes exhibit an enhanced oxidase-like activity on the organic dye TMB within a wide range of concentrations and durations. The oxidase activity increases with increasing Pr amounts in Pr-modified ceria nanocubes within the investigated concentration range. Meanwhile, these Pr-modified ceria nanocubes also show higher reducibility than pure ceria nanocubes. The kinetics of their oxidase mimetic activity is fitted with the Michaelis-Menten equation. A mechanism has been proposed on how the Pr incorporation could affect the energy level of the bands in ceria and hence facilitate the TMB oxidation reaction. The presence of Pr 3+ species on the surface also contributes to the increasing activity of the Pr-modified ceria nanocubes present higher oxidase activity than pure ceria nanocubes.

Using the lanthanide ion praseodymium, Pr(III), metallated ion formation and electron transfer dissociation (ETD) were studied for 25 biological and model acidic peptides. For chain lengths of seven or more residues, even highly acidic peptides that can be difficult to protonate by electrospray ionization will metallate and undergo abundant ETD fragmentation. Peptides composed of predominantly acidic residues form only the deprotonated ion, [M + Pr - H] 2+ ; this ion yields near complete ETD sequence coverage for larger peptides. Peptides with a mixture of acidic and neutral residues generate [M + Pr] 3+ , which cleaves between every residue for many peptides. Acidic peptides that contain at least one residue with a basic side chain also produce the protonated ion, [M + Pr + H] 4+ ; this ion undergoes the most extensive sequence coverage by ETD. Primarily metallated and non-metallated c- and z-ions form for all peptides investigated. Metal adducted product ions are only present when at least half of the peptide sequence can be incorporated into the ion; this suggests that the metal ion simultaneously attaches to more than one acidic site. The only site consistently lacking dissociation is at the N-terminal side of a proline residue. Increasing peptide chain length generates more backbone cleavage for metal-peptide complexes with the same charge state. For acidic peptides with the same length, increasing the precursor ion charge state from 2+ to 3+ also leads to more cleavage. The results of this study indicate that highly acidic peptides can be sequenced by ETD of complexes formed with Pr(III). Copyright © 2017 John Wiley & Sons, Ltd., (Copyright © 2017 John Wiley & Sons, Ltd.)

The understanding of surface chemistry changes on oxygen electrodes is critical for the development of reversible solid oxide fuel cell (RSOFC). Here, we report for the first time that the electrochemical potentials can drastically affect the surface composition and hence the electrochemical activity and stability of PrBaCo2 O5+δ (PBCO) electrodes. Anodic polarization degrades the activity of the PBCO electrode, whereas the cathodic bias could recover its performance. Alternating anodic/cathodic polarization for 180 h confirms this behavior. Microstructure and chemical analysis clearly show that anodic bias leads to the accumulation and segregation of insulating nanosized BaO on the electrode surface, whereas cathodic polarization depletes the surface species. Therefore, a mechanism based on the segregation and incorporation of BaO species under electrochemical potentials is considered to be responsible for the observed deactivation and recovery process, respectively., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

New, deoxyribonucleic acid (DNA) based compounds, functionalized with hexadecyltrimethylammonium chloride (CTMA) and lanthanide hydroxide nanoparticles were synthesized. The spectral measurements suggest that between the DNA-CTMA complex and the lanthanide (III) ions a chemical interaction takes place. The obtained materials exhibit an improved fluorescence efficiency, showing a potential interest for application in photonics, and more particularly, in light emitting devices. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 613-617, 2016., (© 2016 Wiley Periodicals, Inc.)

This article reports on the optical characterization of Pr(3) (+) -, Er(3) (+) - and Nd(3) (+) -doped cadmium lead boro tellurite (CLBT) glasses prepared using the melt quenching method. The visible-near infrared (Vis-NIR) absorption spectra of these glasses were analyzed systematically. On measuring the NIR emission spectra of Er(3) (+) :CLBT glasses, a broad emission band centered at 1536 nm ((4) I13 /2  → (4) I15 /2 ) was observed, as were three NIR emission bands at 900 nm ((4) F3 /2  → (4) I9 /2 ), 1069 nm ((4) F3 /2  → (4) I11 /2 ) and 1338 nm ((4) F3 /2  → (4) I13 /2 ) from Nd(3) (+) :CLBT glasses and an NIR emission band at 1334 nm ((1) G4  → (3) H5 ) from Pr(3) (+) :CLBT glasses at an excitation wavelength (λex ) of 514.5 nm (Ar(+) laser). Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

UVC upconversion emission is observed in a LiYF 4 :Pr 3+ microcrystal under sunlight excitation. The dependence of UVC UC emission intensity on the excitation density of a 488 nm laser and sunlight is investigated. The obtained data indicates that two-photon processes play an important role in UVC UC emission. The UVC UC mechanisms of Pr 3+ under the excitation of a laser and sunlight are presented and discussed. The UVC emission under sunlight excitation has broad prospects for application.

We computationally investigate cascaded amplification in a three-level mid-infrared (IR) Pr(3+)-doped chalcogenide fiber amplifier. The overlap of the cross-sections in the transitions (3)H(6)→(3)H(5) and (3)H(5)→(3)H(4) enable both transitions to simultaneously amplify a single wavelength in the range between 4.25 μm and 4.55 μm. High gain and low noise are achieved simultaneously if the signal is at 4.5 μm. We show that 45% of pump power that is injected at 2 μm can be shifted to 4.5 μm. The efficiency of using a mid-IR fiber amplifier is higher than what can be achieved by using mid-IR supercontinuum generation, which has been estimated at 25%. This mid-IR fiber amplifier can be used in conjunction with quantum cascade lasers to obtain a tunable, high-power mid-IR source.

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma sintering techniques. Polycrystalline ceramics possessing a unique morphology can be achieved by optimizing the process parameters, particularly spark plasma sintering heating rate. The phase and morphology of the synthesized ceramics were investigated in detail using X-ray diffraction, scanning electron microcopy and energy-dispersive X-ray spectroscopy. It was observed that the grains of these bulk Pr-doped SrTiO3 ceramics were enhanced with Pr-rich grain boundaries. Electronic and thermal transport properties were also investigated as a function of temperature and doping concentration. Such a microstructure was found to give rise to improved thermoelectric properties. Specifically, it resulted in a significant improvement in carrier mobility and the thermoelectric power factor. Simultaneously, it also led to a marked reduction in the thermal conductivity. As a result, a significant improvement (> 30%) in the thermoelectric figure of merit was achieved for the whole temperature range over all previously reported maximum values for SrTiO3-based ceramics. This synthesis demonstrates the steps for the preparation of bulk polycrystalline ceramics of non-uniformly Pr-doped SrTiO3.

The RM1 model for the lanthanides is parameterized for complexes of the trications of lanthanum, cerium, and praseodymium. The semiempirical quantum chemical model core stands for the [Xe]4fn electronic configuration, with n =0,1,2 for La(III), Ce(III), and Pr(III), respectively. In addition, the valence shell is described by three electrons in a set of 5d, 6s, and 6p orbitals. Results indicate that the present model is more accurate than the previous sparkle models, although these are still very good methods provided the ligands only possess oxygen or nitrogen atoms directly coordinated to the lanthanide ion. For all other different types of coordination, the present RM1 model for the lanthanides is much superior and must definitely be used. Overall, the accuracy of the model is of the order of 0.07Å for La(III) and Pr(III), and 0.08Å for Ce(III) for lanthanide-ligand atom distances which lie mostly around the 2.3Å to 2.6Å interval, implying an error around 3% only.

The Pr(3+)/Yb(3+) co-doped La2O3 and La(OH)3 nano-phosphors have been synthesized through solution combustion method. The structure and morphology of the samples have been studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The physical and optical properties of the samples have been measured and compared. A broad intense infrared emission centered at 850nm due to (1)I6→(1)G4 transition along with sharp green emission centerd at 513nm due to (3)P0→(3)H4 transition are observed on excitation with 976nm laser. The emission intensity of Pr(3+) is optimized with concentration and it is maximum at 0.08mol%. The annealed samples are found to be more crystalline and emit larger photoluminescence due to removal of quenching centers. The power dependent study of green upconversion emission indicates the involvement of two photons. The phosphor in La(OH)3 phase is more stable though the photoluminescence emission is slightly weak. La(OH)3 is less toxic compared to La2O3 and is biocompatible. It generates more heat and can be used in biothermal treatment., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Pd/CeO2-ZrO2-Pr2O3 (CZP) catalysts with different Ce/Zr molar ratios were synthesized and systematically investigated by XRD, N2 adsorption-desorption, XPS, H2-TPR, OSC and in situ DRIFTS techniques. The results of XPS, in situ DRIFTS, etc., show that the number of oxygen vacancies increases with the increasing Zr content and thus leads to the enhanced metal-support interaction and the accelerative formation rate of nitrate, formate, acetate and carbonate species, resulting in improving catalytic performance for HC and NO elimination, especially for Pd/CZP catalysts with Ce/Zr from 1/2 to 1/3. While Pd/CZP catalysts with higher OSC value (Ce/Zr=4/1-1/2) exhibit better catalytic activity of CO and NO2 elimination. An appropriate concentration of Zr facilitates the diffusion of Pr from the surface to the bulk of the CZP supports, thus forming more homogeneous CZP solid solution and improving the structure/textual stability, which promotes the thermal stability of catalysts. Pd/CZP catalysts with Ce/Zr from 2/1 to 1/2 exhibit good thermal stability., (Copyright © 2014 Elsevier B.V. All rights reserved.)

New fluorophore lanthanide complexes-Cloisite (LCs-C) nanohybrids have been prepared by the intercalation reaction of Cloisite Na(+) with the tricationic lanthanide complexes (1-3), [M(PQ)3(DMF)2(H2O)2](3+) (M=Pr(III) (1), Gd(III) (2), and Dy(III) (3); PQ=9,10-phenanthrenequinone), in aqueous solutions. The X-ray diffraction analysis of the modified clays (LCs-C) showed an increase in the interlayer distance (d) as compared to the pure Cloisite Na(+). Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology of the modified clays and the results were demonstrated a homogeneous morphology for the nanohybrids. The thermal behavior of the LCs-C nanohybrids was investigated using thermogravimetric analysis. Solid-state fluorescence properties of the LCs-C nanohybrids were also investigated. The results show that all tricationic complexes have a significant fluorescence at room temperature when the complexes are adsorbed onto Cloisite., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We report the structural and optical properties of Yb(3+), Pr(3+) co-doped Y2O3 nano-phosphor synthesized through solution combustion method. The structural studies reveal the nano-crystalline structure of the sample. The energy dispersive spectroscopy (EDS) measurements confirm the presence of Y, O, Pr and Yb elements in the sample. Fourier transform infrared studies show the vibrational features of the samples. The fluorescence spectra of the samples have been monitored on excitation with 976 nm and the intense green upconversion emission observed at 552 nm is due to (3)P0→(3)H5 electronic transition. The concentration of Pr(3+) ion in the sample is optimized and the fluorescence intensity is maximum at 0.08 mol% of Pr(3+). The power dependence studies reveal the involvement of two photons in the emission process. The possible mechanism of upconversion has been discussed on the basis of schematic energy level diagram. The sample annealed at higher temperature enhances the fluorescence intensity up to 8 times and this enhancement is discussed in terms of the removal of optical quenching centers. The nano-phosphor can be applicable in the field of display devices and green laser., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The coordination structures formed by calcium complexes with nicotinamide (na), isonicotinamide (ina) and picolinamide (pa) and praseodymium bromide-na are reported. The structures of CaCl2·(C6H6N2O)2·2H2O (Ca-na), CaCl2·(C6H6N2O)2·4H2O (Ca-ina), CaCl2·(C6H6N2O)2·5H2O (Ca-pa) and PrBr3·(C6H6N2O)2·6H2O (PrBr-na) in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Raman spectroscopies. Carbonyl oxygen of nicotinamide is coordinated to Ca(2+), but it is O-monodentate (carbonyl oxygen) and N,O-bidentate ligand (pyridyl nitrogen and carbonyl oxygen) for Pr(3+) to form a chain structure in PrBr-na. For isonicotinamide, only carbonyl oxygen atom is coordinated to Ca(2+). Pyridyl nitrogen and carbonyl oxygen of picolinamide are coordinated to Ca(2+) to form a five-membered ring structure. The crystal structure and spectroscopic results indicate the differences of the coordination of Ca and Pr ions, the changes of hydrogen bonds and conformation of the ligands induced by complexation. Unlike transition metal ions, Sr(2+) or lanthanide ions, Ca(2+) is inclined to coordinate to carbonyl oxygen atoms of the ligands., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We establish the coordination potential of the Schiff base ligand (2-methoxy-6-[(E)-2'-hydroxymethyl-phenyliminomethyl]-phenolate (H2L)) via the isolation of various M(II)-Ln(III) complexes (where M(II) = Ni or Zn and Ln(III) = La or Pr or Gd). Single crystals of these five complexes were isolated and their solid state structures were determined by single crystal X-ray diffraction. Structural determination revealed molecular formulae of [NiGd(HL)2(NO3)3] (1), [NiPr(HL)2(NO3)3] (2) and [Ni2La(HL)4(NO3)](NO3)2 (3), [Zn2Gd(HL)4(NO3)](NO3)2 (4), and [Zn2Pr(HL)4(NO3)](NO3)2 (5). Complexes and were found to be neutral heterometallic dinuclear compounds, whereas 3-5 were found to be linear heterometallic trinuclear cationic complexes. Direct current (dc) magnetic susceptibility and magnetization measurements conclusively revealed that complexes 1 and 4 possess a spin ground state of S = 9/2 and 7/2 respectively. Empirically calculated ΔχMT derived from the variable temperature susceptibility data for all complexes undoubtedly indicates that the Ni(II) ion is coupled ferromagnetically with the Gd(III) ion, and antiferromagnetically with the Pr(III) ion in 1 and 2 respectively. The extent of the exchange interaction for was estimated by fitting the magnetic susceptibility data using the parameters (g = 2.028, S = 9/2, J = 1.31 cm(-1) and zJ = +0.007), supporting the phenomenon observed in an empirical approach. Similarly using a HDVV Hamiltonian, the magnetic data of 3 and 4 were fitted, yielding parameters g = 2.177, D = 3.133 cm(-1), J = -0.978 cm(-1), (for 3) and g = 1.985, D = 0.508 cm(-1) (for 4). The maximum change in magnetic entropy (-ΔSm) estimated from the isothermal magnetization data for was found to be 5.7 J kg(-1) K(-1) (ΔB = 7 Tesla) at 7.0 K, which is larger than the -ΔSm value extracted from 4 of 3.5 J kg(-1) K(-1) (ΔB = 7 Tesla) at 15.8 K, revealing the importance of the exchange interaction in increasing the overall ground state of a molecule for better MCE efficiency.

Luminescence properties of Pr(3+) activated Sr1.5Ca0.5SiO4 phosphors synthesized by solid state reaction method are reported in this work. Blue, orange red and red emissions were observed in the Pr(3+) doped sample under 444nm excitation and these emissions are assigned as (3)P0→(3)H4, (3)P0→(3)H6 and (3)P0→(3)F4 transitions. The emission intensity shows a maximum corresponding to the 0.5wt% Pr(3+) ion. The decay analysis was done for 0.05 and 0.5wt% Pr(3+) doped samples for the transition (3)P0→(3)H6. The life times of 0.05 and 0.5wt% Pr(3+) doped samples were calculated by fitting to exponential and non-exponential curve respectively, and are found to be 156 and 105μs respectively. The non-exponential behaviour arises due to the statistical distribution of the distances between the ground state Pr(3+) ions and excited state Pr(3+) ions, which cause the inhomogeneous energy transfer rate. The XRD spectrum confirmed the triclinic phase of the prepared phosphors. The compositions of the samples were determined by the energy dispersive X-ray spectra. From the SEM images it is observed that the particles are agglomerated and are irregularly shaped. IR absorption bands were assigned to different vibrational modes. The well resolved peaks shown in the absorption spectra are identical to the excitation spectra of the phosphor samples. Pr(3+) activated Sr1.5Ca0.5SiO4 phosphors can be efficiently excited with 444nm irradiation and emit multicolour visible emissions. From the CIE diagram it can be seen that the prepared phosphor samples give yellowish-green emission., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We comparatively study an InGaN laser-diode-pumped continuous-wave laser at ∼607  nm (σ polarization) using differently doped Pr:LiYF 4 single crystals. Maximum output power and slope efficiency at this wavelength were up to 209 mW and 47.1%, respectively, using a 0.2 at. % doped and 8 mm sample. Findlay-Clay analysis shows roundtrip losses, including reabsorption loss at this particular emission of about 1.2% using the 0.2 at. % doped sample, which is lower than that of samples with higher doping concentrations at 0.5 and 1 at. %. Using a 0.15 mm glass plate as a Fabry-Perot etalon, a maximum output power of 73 mW was achieved at ∼604  nm (π polarization) with slope efficiency of 17.2% for what is believed to be the highest result currently.

The Maxwell relation, the Clausius-Clapeyron equation, and a non-iterative method to obtain the critical exponents have been used to characterize the magnetocaloric effect (MCE) and the nature of the phase transitions in Pr0.5Sr0.5MnO3, which undergoes a second-order paramagnetic to ferromagnetic (PM-FM) transition at TC ~ 247 K, and a first-order ferromagnetic to antiferromagnetic (FM-AFM) transition at TN ~ 165 K. We find that around the second-order PM-FM transition, the MCE (as represented by the magnetic entropy change, ΔSM) can be precisely determined from magnetization measurements using the Maxwell relation. However, around the first-order FM-AFM transition, values of ΔSM calculated with the Maxwell relation deviate significantly from those calculated by the Clausius-Clapeyron equation at the magnetic field and temperature ranges where a conversion between the AFM and FM phases occurs. A detailed analysis of the critical exponents of the second-order PM-FM transition allows us to correlate the short-range type magnetic interactions with the MCE. Using the Arrott-Noakes equation of state with the appropriate values of the critical exponents, the field- and temperature-dependent magnetization [Formula: see text] curves, and hence the [Formula: see text] curves, have been simulated and compared with experimental data. A good agreement between the experimental and simulated data has been found in the vicinity of the Curie temperature TC, but a noticeable discrepancy is present for [Formula: see text]. This discrepancy arises mainly from the coexistence of AFM and FM phases and the presence of ferromagnetic clusters in the AFM matrix.

The complete Cd-Pr equilibrium phase diagram was investigated with a combination of powder-XRD, SEM and DTA. All intermetallic compounds within this system, already reported in literature, could be confirmed: CdPr, Cd2Pr, Cd3Pr, Cd45Pr11, Cd58Pr13, Cd6Pr and Cd11Pr. The corresponding phase boundaries were determined at distinct temperatures. The homogeneity range of the high-temperature allotropic modification of Pr could be determined precisely and a limited solubility of 22.1 at.% Cd was derived. Additionally, single-crystal X-ray diffraction was employed to investigate structural details of Cd2Pr; it is isotypic to the AlB2-type structure with a z value of the Cd site of 0.5. DTA results of alloys located in the adjacent two-phase fields of Cd2Pr suggested a phase transformation between 893 and 930°C. For the phase Cd3Pr it was found that the lattice parameter a changes linearly with increasing Cd content, following Vegard's rule. The corresponding defect mechanism could be evaluated from structural data collected with single-crystal XRD. Introduction of a significant amount of vacancies on the Pr site and the reduction in symmetry of one Cd position (8c to 32f) resulted in a noticeable decrease of all R-values.

Pr and Nd co-doped Ce-Zr oxide solid solutions (CZPN) were prepared using co-precipitation and microemulsion methods. It is found that only using supercritical CO(2) drying can result in a significant improvement of specific surface area and oxygen storage capacity at lower temperatures for CZPN after aging at 1000°C for 12 h in comparison with those using conventional air drying and even supercritical ethanol drying. Furthermore, the cubic structure was obtained in spite of the fact that the atomic ratio of Ce/(Ce+Zr+Pr+Nd) is as low as 29%. The high thermal stability can be attributed to the loosely aggregated morphology and the resultant Ce enrichment on the nanoparticle surface, which are caused by supercritical CO(2) drying due to the elimination of surface tension effects on the gas-liquid interface.

The complex between (17)O-enriched DOTA (tetraazacyclododecanetetraacetic acid) and praseodymium(III) (Pr(3+)) was studied in aqueous solution by variable-temperature (17)O NMR at 14.1 T. pH effects as well as the influence of metal ions free in solution were investigated. At low temperature, the so-called TSAP and SAP conformations give rise to distinct signals for the oxygen atoms coordinated to the metal ion (O2); coalescence occurs between 20 and 30 °C. In contrast, a single signal was detected for the noncoordinated oxygen atoms (O1) in the entire investigated temperature range, i.e. between -3 and 135 °C. At high temperature, the spectra exhibit signal broadening that reveals the interchange of the O1 and O2 oxygen atoms of the carboxylate groups. The linewidths measured for O1 were deconvolved into contributions from quadrupole relaxation and chemical exchange, allowing the corresponding activation barriers to be determined. The present (17)O dynamic NMR study provides the first quantitative experimental data characterizing the interchange of the oxygen atoms in a DOTA chelate of a lanthanide metal ion. The activation entropy of this process is negligible and the activation enthalpy is found to range between 66 and 77 kJ mol(-1), depending on the pH and the presence of free Pr(3+) ions in solution. These data support the results of a previous computational study according to which the exchange mechanism involves the internal rotation of the carboxylate groups.

The rational self-assembly of mono-lacunary Keggin clusters with 4d and 4f metal salts via a conventional method has yielded two novel polyoxometalate-based 4d-4f heterometallic compounds containing lacunary Keggin anions connected to ten metal atoms: {[Ag{Ag2(H2O)4}{Ln(H2O)6}2H ⊂ {SiW11Ln(H2O)4O39}2]·nH2O (Ln = Ce and n = 7 for 1, Ln = Pr and n = 3 for 2). Their structures were determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. A structural feature in 1 and 2 is that each [SiW11O39](8-) cluster (SiW11) is connected to ten metals (five Ag(+) and five Ln(3+) cations), representing the highest number of connected metal atoms to any mono-lacunary Keggin anion to date. This large connectivity leads to a structure with a purely inorganic 3D framework with two kinds of channels along the [100] and [010] directions. The magnetic properties of both compounds show the expected magnetic moments (0.8 and 1.6 amu K mol(-1) per Ce(3+) and Pr(3+) ion, respectively) and confirm the presence of isolated Ce(3+) and Pr(3+) ions.

Near infrared (NIR)-emitting persistent luminescent nanoparticles (PLNPs) have great potential for in vivo bioimaging with the advantages of no need for in situ excitation, high signal-to-noise ratio, and deep tissue penetration. However, functional NIR-emitting PLNPs with long afterglow for long-term in vivo imaging are lacking. Here, we show the synthesis of NIR-emitting long-persistent luminescent nanoparticles (LPLNPs) Zn2.94Ga1.96Ge2O10:Cr(3+),Pr(3+) by a citrate sol-gel method in combination with a subsequent reducing atmosphere-free calcination. The persistent luminescence of the LPLNPs is significantly improved via codoping Pr(3+)/Cr(3+) and creating suitable Zn deficiency in zinc gallogermanate. The LPLNP powder exhibits bright NIR luminescence in the biological transparency window with a superlong afterglow time of over 15 days. A persistent energy transfer between host and Cr(3+) ion in the LPLNPs is observed and its mechanism is discussed. PEGylation greatly improves the biocompatibility and water solubility of the LPLNPs. Further bioconjugation with c(RGDyK) peptide makes the LPLNPs promising for long-term in vivo targeted tumor imaging with low toxicity.

We have investigated quadrupole effects in tetragonal crystals of PrCu2Si2 and DyCu2Si2 by means of low-temperature ultrasonic measurements. The elastic constant C44 of PrCu2Si2 exhibits pronounced softening below 70 K down to a Néel temperature TN = 20 K, which is described in terms of a quadrupole susceptibility for a Γ5 doublet ground state and a Γ3 singlet first excited state located at 15.6 K in the crystalline electric field scheme. The C44 and C66 of DyCu2Si2 also show softening below 70 K down to TN1 = 9.7 K. A low-lying pseudo-sextet state consisting of three Kramers doublets of Γ6⊕2Γ7 brings about softening of C44 and C66 in DyCu2Si2.

We have investigated the magnetic and transport properties of a noncentrosymmetric compound PrRhSi3 by dc magnetic susceptibility χ(T), isothermal magnetization M(H), thermoremanent magnetization M(t), specific heat Cp(T), electrical resistivity ρ(T,H) and muon spin relaxation (μSR) measurements. At low fields χ(T) shows two anomalies near 15 and 7 K with an irreversibility between ZFC and FC data below 15 K. In contrast, no anomaly is observed in Cp(T) or ρ(T) data. M(H) data at 2 K exhibit very sharp increase below 0.5 T and a weak hysteresis. M(t) exhibits very slow relaxation, typical for a spin-glass system. Even though the absence of any anomaly in Cp(T) is consistent with the spin-glass type behavior, there is no obvious origin of spin-glass behavior in this structurally well ordered compound. The crystal electric field (CEF) analysis of Cp(T) data indicates a CEF-split singlet ground state lying below a doublet at 81(1) K and a quasi-triplet at 152(2) K. The ρ(T) data indicate a metallic behavior, and ρ(H) exhibits a very high positive magnetoresistance, as high as ~300% in 9 T at 2 K. No long range magnetic order or spin-glass behavior was detected in a μSR experiment down to 1.2 K.

Unique from other rare earth dialuminides, PrAl(2) undergoes a cubic to tetragonal distortion below T = 30 K in a zero magnetic field, but the system recovers its cubic symmetry upon the application of an external magnetic field of 10 kOe via a lifting of the 4f crystal field splitting. The nuclear Schottky specific heat in PrAl(2) is anomalously high compared to that of pure Pr metal. First principles calculations reveal that the 4f crystal field splitting in the tetragonally distorted phase of PrAl(2) underpins the observed unusual low temperature phenomena.

The 4f-5d excitation and emission spectra of Ce(3+) and Pr(3+) ions in Ca9Lu(PO4)7 as recently reported (2012 J. Phys.: Condens. Matter 24 385502) were further analyzed and simulated by employing the effective Hamiltonian model for the 4f(N) and 4f(N-1)5d electronic configurations of impurity lanthanide ions and the exchange charge model of crystal-field theory. The multi-site effect on the 4f-5d transition spectra was explicitly discussed from the points of view of the local structure and site occupation ratios of lanthanide ions in Ca9Lu(PO4)7. An excellent agreement between the predicted and measured spectra confirms the validity of the performed calculations. Based on these energy level and intensity calculation results, the radiative lifetimes of the 5d-4f emissions of Ce(3+) and Pr(3+) ions have been modeled to show nearly independent temperature trends. Comparison with the measured lifetimes suggests the nonradiative relaxation process in this host is probably related to the intrinsic defect states. In addition to the studies of the 4f-5d transitions, a general theoretical scheme to calculate the lowest 4f-6s transition energy of the Ce(3+) ion was proposed for the first time on the basis of the ligand polarization model. The predicted 6s energy position of the Ce(3+) ion in Ca9Lu(PO4)7 is solid evidence corroborating our previous spectroscopic assignment.

Photoluminescence spectra and luminescence kinetics of pure CaMoO(4) and CaMoO(4) doped with Ln(3+) (Ln = Pr or Tb) are presented. The spectra were obtained at high hydrostatic pressure up to 240 kbar applied in a diamond anvil cell. At ambient pressure undoped and doped samples exhibit a broad band emission extending between 380 and 700 nm with a maximum at 520 nm attributed to the MoO(4)(2-) luminescence. CaMoO(4) doped with Pr(3+) or Tb(3+) additionally yields narrow emission lines related to f-f transitions. The undoped CaMoO(4) crystal was characterized by a strong MoO(4)(2-) emission up to 240 kbar. In the cases of CaMoO(4):Pr(3+) and CaMoO(4):Tb(3+), high hydrostatic pressure caused quenching of Pr(3+) and Tb(3+) emission, and this effect was accompanied by a strong shortening of the luminescence lifetime. In doped samples, CaMoO(4):Pr(3+) and CaMoO(4):Tb(3+), quenching of the emission band attributed to MoO(4)(2-) was also observed, and at pressure above 130 kbar this luminescence was totally quenched. The effects mentioned above were related to the influence of the praseodymium (terbium) trapped exciton PTE (ITE-impurity trapped exciton) on the efficiency of the Pr(3+) (Tb(3+)) and MoO(4)(2-) emissions.

The interactions of Pr(III) with nucleosides and nucleotides have been studied in different organic solvents employing absorption difference and comparative absorption spectrophotometry. The magnitudes of the variations in both energy and intensity interaction parameters were used to explore the degree of outer and inner sphere co-ordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Various electronic spectral parameters like Slater-Condon (F(k)), Racah (E(k)), Lande parameter (ξ(4f)), Nephelauxatic ratio (β), bonding (b(1/2)), percentage covalency (δ) and intensity parameters like oscillator strength (P) and Judd Ofelt electronic dipole intensity parameter (T(λ), λ=2,4,6) have been evaluated. The variation of these evaluated parameters were employed to interpret the nature of binding of Pr(III) with different ligands i.e. Adenosine/ATP in presence and absence of Ca(2+)., (Copyright © 2012 Elsevier B.V. All rights reserved.)

We report on the effect of oxygen on the Jahn-Teller distortion and dynamic magnetic properties of low hole-doped Pr(0.9)Ca(0.1)MnO(3) thin films, using micro-Raman spectroscopy and the temperature dependent ac susceptibility, as a function of the frequency, dc field bias, and thermal cycles. The as-grown and vacuum annealed thin films show a high amount of magnetic frustration and inferior ferromagnetic ordering compared with the oxygen annealed thin films. It has been found that the amount of magnetic frustration in the film is interlinked with the Jahn-Teller distortion and domain wall dynamics. An attempt has been made to understand the origin and nature of the magnetic frustration.

Objective: Many studies have attempted to assess the significance of the use of the β(-)particle emitter praseodymium-142 ((142)Pr) in cancer treatment. As praseodymium oxide (Pr(2)O(3)) powder is not water soluble, it was dissolved in HCl solution and the resultant solution had to be pH adjusted to be in an injectable radiopharmaceutical form. Moreover, it was shown that the nanosized neodymium oxide (Nd(2)O(3)) induced massive vacuolization and cell death in non-small-cell lung cancer. In this work, the production of (142)Pr was studied and water-dispersible nanosized Pr(2)O(3) was proposed to improve the application of (142)Pr in nuclear medicine., Materials and Methods: Data from different databases pertaining to the production of (142)Pr were compared to evaluate the accuracy of the theoretical calculations. Water-dispersible nanosized Pr(2)O(3) was prepared using a poly(ethylene glycol) (PEG) coating or PEGylation method as a successful mode of drug delivery. Radioactive (142)Pr(2)O(3) was produced via a (142)Pr(n,γ)(142)Pr reaction by thermal neutron bombardment of the prepared sample., Results: There was good agreement between the reported experimental data and the data based on nuclear model calculations. In addition, a small part of nano-Pr(2)O(3) particles remained in suspension and most of them settled out of the water. Interestingly, the PEGylated Pr(2)O(3) nanoparticles were water dispersible. After neutron bombardment of the sample, a stable colloidal (142)Pr(2)O(3) was formed., Conclusion: The radioactive (142)Pr(2)O(3) decays to the stable (142)Nd(2)O(3). The suggested colloidal (142)Pr(2)O(3) as a multifunctional therapeutic agent could have dual roles in cancer treatment as a radiotherapeutic agent using nanosized (142)Pr(2)O(3) and as an autophagy-inducing agent using nanosized (142)Nd(2)O(3).

A series of Pr(3+) (1-9 mol%) doped CdSiO(3) nanophosphors have been prepared for the first time by a low temperature solution combustion method using oxalyldihydrizide (ODH) as a fuel. The final product was characterized by Powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The average crystallite size was calculated using Debye-Scherrer's formula and Williamson-Hall (W-H) plots and found to be in the range 31-37 nm. The optical energy band gap (E(g)) of undoped for Pr(3+) doped samples were estimated from Tauc relation which varies from 5.15-5.36 eV. Thermoluminescence (TL) properties of Pr(3+) doped CdSiO(3) nanophosphor has been investigated using γ-irradiation in the dose range 1-6 kGy at a heating rate of 5 °C s(-1). The phosphor shows a well resolved glow peak at ∼171 °C along with shouldered peak at 223 °C in the higher temperature side. It is observed that TL intensity increase with increase of Pr(3+) concentration. Further, the TL intensity at 171 °C is found to be increase linearly with increase in γ-dose which is highly useful in radiation dosimetry. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics was estimated by Luschiks method and the results are discussed., (Copyright © 2012 Elsevier B.V. All rights reserved.)