Pr Content Research Articles

Thermoluminescent response of LaAlO3:Pr3+ under X-ray beams effect

Thermoluminescent (TL) dosimeters are the most used, since they can store information, due to exposure to radiation. Rare earth doped lanthanum aluminate (LaAlO3) ceramic has attracted great attention in recent years for many applications because it shows excellent properties such as thermal stability, color light emission as well as high thermoluminescent intensity. In the present work, TL glow curve under diagnostic X-ray beam was obtained. According to the literature, procedures in interventional cardiology are Thermoluminescent glow curve was analyzed using a Harshaw 3500 TL reader coupled to a personal computer for storage information and future analysis. For irradiation processes was used a diagnostic X-ray source Siemens 256-slice computed tomography (CT) Somaton drive model. TL response of trivalent praseodymium doped lanthanum aluminate as a function of dopant concentration was increasing as concentrations of Pr3+ ion in LaAlO3 was increased. The increase in TL glow peak sensitivity was increased up to 2 % concentration of Pr3+ ion. This TL glow curve exhibited a broad peak centered at 190°C and little shoulder which is consider as the second peak centered at 260°C respectively. The nature of the glow curve form in samples is attributed to at least one type of the trap with relates at least one type of the defect. After experimental results LaAlO3:Pr3+ can be used as thermoluminescent material for diagnostic X-ray beams measurements.

Effect of adding Pr on the microstructure and hot tearing sensitivity of as-cast Al-Cu-Mg alloys

In this study, the effect of Pr on the microstructure and hot tearing sensitivity of the Al-4.4Cu-1.5Mg-0.15Zr alloy was studied using a self-made multi-channel “cross” hot tearing test device. With the increase in Pr content from 0 to 0.5 wt%, the average grain size, modified hot tearing sensitivity (HTS 1 ), and cracking susceptibility coefficient (CSC) of the alloy initially decreased and subsequently increased. Similarly, the range of the solidification temperature exhibited a small decrease. In contrast to the alloy without Pr, the average grain size decreased from 167.0 to 81.5 μm; the range of the solidification temperature decreased from 143.71 to 137.90 °C; the HTS 1 value of the alloy decreased from 228 to 60, and the CSC value decreased from 0.629 to 0.159 with the addition of 0.3 wt% Pr. The mechanism of reducing the hot tearing sensitivity of the alloy with the addition of Pr indicated that the microstructure was refined and the solidification temperature range was decreased. This was conducive to the increased formation of intergranular bridging at the grain boundary. Finally, the hot tearing sensitivity of the alloy was reduced. • The effect of trace addition of Pr (0–0.5 wt%) on the microstructure of Al-Cu-Mg alloy was studied. • The hot tearing sensitivity was studied by a self-made multi-channel “cross” hot tearing test device. • The hot tearing mechanism of alloy with addition of Pr was studied based on multi-theory.

Polyanionic amphiphilic polymer based supramolecular dye-host assembly: Highly selective turn–on probe for protamine sensing

Here in we report a supramolecular dye-host assembly, forming through non-covalent interaction between a cationic dye, quinaldine red (QR), and polyanionic amphiphilic polymer, polystyrene sulfonate (PSS), as an efficient fluorescence turn-on probe for protamine (Pr) sensing. Formation of QR-PSS complex converts nonfluorescent QR into moderately fluorescent in nature, due to restriction in the structural agility of the dye. Interestingly, fluorescence from QR-PSS complex enhances further quite largely by the presence of Pr, attributing to the formation of QR-PSS-Pr ternary complex. Binding with multi-cationic Pr, polyanionic PSS experiences large charge neutralization, increasing its hydrophobic character. This leads to folding/coiling of PSS, creating several cavity-like patches in its modified structure. The QR molecules that had been initially bound to PSS surface and exposed to bulk aqueous phase, get incorporated suitably into these cavities, arresting the structural flexibility of the dyes significantly. Accordingly, there is a large reduction in the non-radiative de-excitation processes for the excited dye, triggering a noteworthy fluorescence turn-on for QR-PSS complex. This eventually allows us to estimate Pr concentration very effectively, with limit of detection as low as ∼14.8 nM in buffer solution and ∼0.18 μM in 1% human serum sample. Importantly, amongst all the reported dye-PSS systems, QR-PSS is found to be the first ever system that shows fluorescence turn-on response towards Pr. Consequently, present system provides several advantages like high signal to noise ratio, low background, high brightness, minimum possibility of false signal, etc., making it more effective than the previously reported dye-PSS systems.

Effect of A-site doping on electrical properties of La2-xPrxFeCoO6 double perovskite prepared by sol-gel technique

The present work deals with the synthesis, characterization, and thermoelectric properties of La2-xPrxFeCoO6 (x ​= ​0.0, 0.25, 0.50, 0.75, and 1.0) ceramics. The crystal structure, microstructural characteristics, electrical properties, and thermal transport characteristics of the sintered samples were studied. The samples prepared by sol-gel technique resulted in the presence of nanocrystalline single phase material after 6 ​h of sintering, and the increased crystallite size with increasing Pr concentration alongwith the occurrences of multivalent oxidation states of La, Pr, Fe, Co and O. The conductivity investigation revealed the presence of a nearest neighbor hopping charge carrier conduction mechanism in the entire samples, i.e., an increasing Pr-content result in enhanced conductivity at every examined temperature. For the entire composition range (x), conductivity increases with increasing temperature up to maximum value at a transition temperature followed by a downward trend, indicating the metallic behavior (reduction in semiconducting behavior) due to the presence of oxygen deficiency at higher temperature. Positive S values indicate the presence of p-type charge carrier in La2-xPrxFeCoO6 double perovskite and intrinsic behavior was conserved with increasing doping concentration (x). Temperature dependent power factor increases with increasing Pr-content and the maximum values were observed at their transition temperatures. Within recorded temperature, the highest Figure of Merit (ZT ​= ​∼0.87) was observed at x ​= ​1.0 in La2-xPrxFeCoO6 compound, which was 5.4 times more as compare to x ​= ​0.0.

Photosynthesis, Nitrogen Allocation, Non-Structural Carbohydrate Allocation, and C:N:P Stoichiometry of Ulmus elongata Seedlings Exposed to Different Light Intensities.

The leaf photosynthetic capacity, leaf N partitioning, non-structural carbohydrate content, C, N, and P contents of endangered U. elongata seedlings exposed to different light intensities were compared in this study. The most favorable light condition for the survival and growth of U. elongata seedlings in the present study was 100% full sunlight, as this induced higher Pn, PNUE, PC, PR, PB, and NSC content relative to shade-treated seedlings. PNUE, PR, PC, and PB in U. elongata seedling leaves decreased under 40% and 10% full sunlight, while PL increased, indicating that shade increased the light capture efficiency of photosystem (PS) II but decreased electron transfer from PSII to PSI. Furthermore, leaf N content increased with shade intensity, revealing an adaptive strategy for poor light environments. Additionally, the smallest leaf biomass, Pn, WUE, and CE values and C:N and C:P ratios in stems and leaves were observed under 10% full sunlight. These results indicate that seedlings growing under 40% full sunlight will benefit U. elongata conservation.

Influence factor of Pr(III) recovery kinetics from rare-earth simulant wastewater by PAN microtubule hyperfiltration reactor

Abstract PAN microtubule hyperfiltration reactor (PMHR) with organic phosphate system containing simulant wastewater section with buffer solution acetic acid and enrichment section with nitric acid solution and organic phosphate C16H35O4P (Di (6-methylheptyl) phosphate) dissolved in benzin, has been studied for the praseodymium (III)[expressed as Pr(III) or Pr3+] recovery in the rare-earth simulant wastewater. Many factors of Pr(III) recovery using PMHR need to explore, including hydrogen ion concentration (or pH), cinit of Pr(III) and different ionic strength of rare-earth simulant mine wastewater, volume ratio of C16H35O4P with benzin and nitric acid solution (O/W), nitric acid concentration, C16H35O4P concentration, different acid solution of enrichment section on Pr(III) recovery with PMHR were investigated. The experimental results show that the best recovery conditions of Pr(III) were obtained as that nitric acid concentration was 4.00 mol/L, C16H35O4P concentration was 0.200 mol/L, and O/W was 0.6 in the enrichment section, and pH value was 4.90 in the wastewater section. Ionic strength of rare-earth simulant mine wastewater had no obvious effect on Pr(III) recovery. When cinit of Pr(III) concentration was 1.67 × 10−4 mol/L, the recovery percentage of Pr(III) was up to 94.7% in 160 min. The kinetic equations were developed, and diffusion coefficient in the microtubule reactor and thickness of diffusion layer between the wastewater section and the microtubule pipe wall were obtained by linear slope method. They were 4.16 × 10−6 m2/s and 4.65 μm, respectively. PMHR, owing to a large number of C16H35O4P was used in the enrichment section, can renewal the losing carrier of microtubule reactor. As a result, the recovery percentage of Pr(III) was increased, the stability of PMHR system was enhanced, and the life span of the PMHR system was extended.

Efficient ammonia synthesis over Ru/CeO2-PrOx catalysts with controlled Ru dispersion by Ru-Pr interaction

Ru/CeO2-PrOx catalysts for NH3 synthesis were prepared using the urea-based homogeneous co-precipitation method, and the effect of Pr-doped CeO2 support on the catalytic activity was investigated. An optimal range of Pr content (25–75 %) improved NH3 synthesis activity. CO pulse adsorption and operando X-ray absorption fine structure (XAFS) measurements revealed that the increase in NH3 synthesis activity was due to the improvement in Ru dispersion by the interaction between PrOx and Ru, rather than the generally discussed Ce3+/Ce4+ ratio. However, excess Pr doping prevented the Ru reduction and formation of active sites. In this Ru/CeO2-PrOx catalyst system, the activity is governed by the number of active sites that can be controlled by the Pr content. In the high-pressure evaluation (5 MPaG), the NH3 synthesis rate of the Ru/CeO2-PrOx catalyst (Ce/Pr = 1) was 9.0 mmol g-1h−1, which is 1.4 times higher than that of the Ru/CeO2 catalyst.

Effects of Pr concentration on the structural, mechanical and optical properties of KCl0.5Br0.5:Pr3+ crystals

KCl0.5Br0.5:XPr3+ [X = 0.0 (pure KCl0.5Br0.5), 0.002, 0.004, 0.006, 0.008, 0.01, 0.02 and 0.04] crystals were successfully grown by Czockralski (Cz) pulling method and the structural, mechanical and optical properties of crystals were thoroughly investigated. X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) studies indicated that the Pr ions have been incorporated into the KCl0.5Br0.5 host lattice and existed mainly as trivalent Pr. UV–Vis absorption spectra showed that the presence of peaks at 211, 227, 293, 457, 479, 494 and 601 nm. Hardness was found to increase with increasing of in Pr3+ concentration and indentation load, the hardness of the Pr doped crystals were larger than the un-doped crystal and the reverse indentation size effect was observed. The intensity of photoluminescence (PL) peaks was strongly depended on the Pr3+concentration. thermo-luminescence (TL) glow curves exhibited one peaks at 63–76 °C, indicating that one kind of trap existed in the crystals. The optimal luminous (both PL and TL) properties the KCl0.5Br0.5:XPr3+ crystals were obtained at X = 0.006. These results indicated that the KCl0.5Br0.5:Pr3+ crystals could be considered as a promising candidate for their use in optical and dosimetry applications.

Structural degradation behavior of Mg2-Pr Ni4 upon hydrogenation

Hydrogenation properties of Mg2-xPrxNi4 (x = 1.0, 1.2 and 1.4) and their structural degradation (amorphization) upon hydrogenation have been investigated using in-situ X-ray diffraction. In Mg1.0Pr1.0Ni4, the crystalline phase was stable up to a temperature of 573 K under 3 MPa of hydrogen pressure and amorphization did not take place. Mg0.6Pr1.4Ni4 was directly transformed to an amorphous hydride, Mg0.6Pr1.4Ni4H~7.2, while Mg0.8Pr1.2Ni4 transformed to amorphous Mg0.8Pr1.2Ni4H~6 through the formation of Mg0.8Pr1.2Ni4H~4 having an orthorhombic structure. While reversible hydrogen absorption and desorption was observed in the first plateau region between Mg0.8Pr1.2Ni4 and Mg0.8Pr1.2Ni4H~4. First principles calculation indicate that the elastic modulus and bulk modulus decreased with increase of the Pr content and hydrogen content in Mg2-xPrxNi4 suggesting that decrease of bulk modulus induce amorphization upon hydrogen absorption. These results clearly indicate that the hydrogenation properties, the stability of crystalline hydride and amorphization behavior strongly depend on the chemical composition of Mg2-xPrxNi4 and their hydrogen content.

Pyrochlore-like ZrO2-PrOx compounds: The role of the processing atmosphere in the stoichiometry, microstructure and oxidation state

The object of this work is to study the relation between composition, microstructure and oxidation state of Pr2±xZr2∓xO7±y materials produced by the laser–floating zone (LFZ) technique. Three compositions are studied, nominally Pr1.7Zr2.3O7+y, Pr2Zr2O7+y and Pr2.24Zr1.76O7±y, all within the pyrochlore field in the ZrO2–PrOx phase diagram. Samples have been processed under four different atmospheres (O2, air, N2 and 5%H2(Ar)), so as to vary the environmental conditions from oxidising to reducing. Sample colouration ranged from dark brown to bright green, owing to varying Pr4+ content. A close correlation is found between the phase homogeneity, the microstructure and the Pr content. Pr–deficient samples present a homogeneous microstructural aspect and composition, whereas Pr–rich compositions always break into 5–25 µm–sized grains with pyrochlore phases at the grain centre and ill–crystallised, Pr–rich oxidised phases at the grain–boundaries. Raman spectroscopy shows that different types of oxygen disorder occur depending on composition and processing atmosphere: in Pr–poor samples oxygen interstitials are created to compensate for Zr4+ excess charge, whereas in Pr–rich samples oxygen disorder occurs around the Pr3+ or Pr4+ ions substituting for Zr4+, because of size–mismatch. Magnetic measurements showed a high Pr4+ content, which has been attributed to several factors: the highly oxidised state of the feedstock material, the segregation of Pr and O–rich grain boundaries in compositions with praseodymium molar rate> 0.5, and the lower oxide–ion conductivity for PZO compositions, compared to either Pr–poor or Pr–rich compositions. Post–processing thermal annealing in a vacuum at 1000 °C enabled total Pr reduction, with the exception of the Pr–rich P2.24 samples, where some Pr4+ ions remained in the oxidised state.

Interplay of multiple structural phase and magnetic response of Bi1-xPrxFeO3 ceramics

The detailed structural phase transition induced by chemical substitution in Bi1-xPrxFeO3 (x = 0.1–0.2) polycrystalline ceramics is reported herein. Pr3+ substitution is observed to destabilize the polar R3c symmetry due to the chemical strain effect caused by the large ionic radius mismatch at the Bi-site. The R3c rhombohedral phase can only be stabilized up to 14 mol% of Pr doping (x < 0.14); the phase transition starts to appear at a higher Pr concentration (x ≥ 0.14), forming a morphotropic phase boundary between the R3c rhombohedral and Pbam orthorhombic phases. Increasing Pr concentration causes the magnetic transition from a pure antiferromagnetic to a weak ferromagnetic state as a result of the evolution of crystal structure. The influence of PB spins on the magnetic properties of Bi1-xPrxFeO3 compounds has been uncovered through manipulation of the mixed phase state by an electric field, temperature, and structural relaxation.

Novel optical temperature sensors based on the emission of the Pr3+ ions doped Ca3(M,Ga)5O12 (M5+ = Nb, Ta) garnet phosphors

Pr3+-doped Ca3(Nb,Ga)5O12 (Pr:CNGG) and Ca3(Ta,Ga)5O12 (Pr:CTGG) phosphors with garnet structure have been systematically investigated as optical thermometric materials for potential applications in the field of sensing technology, for the first time to our knowledge. The ceramic samples of Pr:CNGG and Pr:CTGG with different concentrations of Pr3+ ions have been obtained by the solid-state reaction method. A comparative analysis to evidence the influence of the position of the inter-valence charge transfer (IVCT) states on the excited-state dynamics of Pr3+ ions in CNGG and CTGG materials is presented. The optical thermometric properties of the Pr:CNGG and Pr:CTGG samples were studied. The luminescence thermal quenching mechanisms of the 3P0 and 1D2 levels were investigated in detail based on the luminescence intensity ratio (LIR) of 1D2→3H4 / 3P0→3H4 (I606/I487) transitions over an extended temperature range (10–700 K). The maximum relative sensitivities were determined to be 1.64% K−1 at 10 K for 7 at% Pr:CTGG and 2.4% K−1 at 430 K for 1 at% Pr:CNGG, thus proving their potential as high-sensitivity temperature sensors in cryogenic and high-temperature domains, respectively.

Exploring the Genetic Variability and Potential Correlations Between Nutritional Quality and Agro-Physiological Traits in Kabuli Chickpea Germplasm Collection (Cicer arietinum L.).

Chickpea is an important source of plant-based protein and mineral elements such as iron (Fe) and zinc (Zn). The development of superior high-yielding germplasm with high nutritional value becomes central for any breeding program. Chickpea biofortified and nutrient-dense seeds can contribute to mitigate many human health problems associated with protein and micronutrients deficiency. In this study, 282 advanced chickpea lines were grown under field conditions to evaluate their agronomic performances and nutritional quality value. The trial was conducted under winter planting conditions during the cropping season 2017/2018 at ICARDA-Marchouch research station, Morocco. Results revealed high genetic variation and significant differences between the tested genotypes for all studied parameters. Under field conditions, the grain yield (GY) varied from 0.57 to 1.81 (t.ha–1), and 100-seed weight (HSW) ranged from 23.1 to 50.9 g. Out of the 282 genotypes, only 4 genotypes (i.e., S130109, S130058, S130066, and S130157) combined both good agronomic performances (GY, HSW) and high nutritional quality (protein, macronutrients, and micronutrients). Protein content ranged from 18.9 to 32.4%. For the whole collection, Fe content varied from 31.2 to 81 ppm, while Zn content ranged from 32.1 to 86.1 ppm. Correlation analysis indicated that the studied traits were significantly intercorrelated, with negative correlation between protein content and Zn concentration. Positive correlations were observed between grain filling time (F2M) and the micronutrients Zn, Cu, and Mn and macroelements K and Mg. Low positive correlation was also recorded between Pr and Fe concentrations. No significant correlation was observed between Fe and Zn. Positive correlations observed between main agronomic and nutritional quality traits makes easy any simultaneous enhancement when combining these traits.

Agricultural waste for the development of low cost Ca2SiO4:Pr3+ phosphors

Rice husk (RH) and egg shells (ES) are agricultural waste products which are converted into SiO2 (RH ash (RHA)) and CaO (ES ash (ESA)) powders, respectively, through firing and annealing at optimised temperature and time duration. By using these derived SiO2 and CaO raw chemicals, obtained from renewable sources, prepared Ca2SiO4 phosphors doped with Pr3+ ions through solid state reaction method. XRD reveals that the RHA contains SiO2 crystal nature with standard data and tridymite phase. ESA patterns confirm the purity of CaO with cubic phase. Ca2SiO4:Pr3+ (0.05 mol%) phosphor was confirmed with structure of ICDD card No. 01-083-0464 with particles are of irregular sizes and shapes. Excitation spectra of Ca2SiO4:Pr3+ phosphors exhibit highest intensity at 447 nm due to 3H4→3P2 transition. Emission spectra of Pr3+-doped phosphors reveal more intense band at 606 nm which is attributed to 1D2→3H4 transition with reddish-orange emission. CIE co-ordinates of the present phosphors are shifted from reddish-orange to yellow region with increase in Pr3+ ion concentration. Decay curves of the synthesized phosphors exhibit nearly mono-exponential nature for 0.01 mol% concentration and then changes to the bi-exponential nature for ≥0.05 mol% concentrations of Pr3+ ions owing to energy transfer via cross-relaxation channels confirming dipole-dipole interaction type. All the observed results recommend that the synthesized phosphors can be suitable for solid state lighting applications.

العلاقات العامة الرقمية ودورها في ترتيب أولويات الجماهير ( دراسة تحليلية لموقع منظمة الامم المتحدة الالكتروني )

يرمي البحث الى معرفة الكيفية التي تعمل بها منظمة الامم المتحدة عبر موقعها الالكتروني في ترتيب اولويات الجماهير نحو القضايا الدولية ، عن طريق معرفة اليات العلاقات العامة الرقمية المستخدمة في مضامين العلاقات العامة الرقمية في ترتيب اولويات الجماهير نحو القضايا الدولية التي تتعامل معها .&#x0D; استخدم الباحث المنهج المسحي تحقيقا لاهداف البحث، وقام الباحث بأستخدام اداة ( تحليل المضمون ) بهدف معرفة ترتيب القضايا الدولية في الموقع الالكتروني وهي قضايا الصحة ، والسلم والامن ، والمساعدات الانسانية ، وحقوق الانسان ، والمرأة ، والمهاجرون واللاجئون والنازحون ، والتنمية الاقتصادية ، وشؤون الامم المتحدة ، والثقافة والتعليم ، والبيئة والمناخ ، والتنمية المستدامة ، والقانون ومنع الجريمة .&#x0D; من أهم النتائج التي توصل اليها الباحث : محاولة منظمة الامم المتحدة عبر مضامينها الاتصالية ترتيب اولويات الجماهير نحو القضايا الدولية ، عن طريق ابراز القضايا الدولية المهمة عن القضايا الدولية الاقل اهتماما ، ومن ثم ترتيب اولويات الجماهير نحو هذه القضايا ، فقد حاولت منظمة الامم المتحدة عبر الفيديو الرقمي ترتيب اولويات الجماهير نحو القضايا الدولية ، مما لها من مميزات مهمة لأنها تمتلك عنصر الحركة الذي يشعر الجمهور بأنه في قلب الحدث ، والذي يؤدي الى ابراز القضايا الدولية المهمة عن القضايا الدولية الاقل اهتماما ، ومن ثم ترتيب أولويات الجماهير نحو هذه القضايا

Observation of up conversion/ down conversion luminescence and structural analysis of La2Zr2O7: Pr3+ nano phosphors

Charge transfer band (CTB) transition significantly improves the photoluminescence properties of phosphor materials due to its higher absorption efficiency than the characteristic excitations of rare-earth ions. La2Zr2O7 (LZO): Pr3+ phosphors with varying doping concentrations of Pr3+ were synthesized through the hydrothermal method. The formation of the pure pyrochlore phase was confirmed from powder X-ray diffraction (XRD). The structural analysis was performed from Rietveld refinement of the XRD data. Field emission electron microscope (FESM) equipped with EDX spectroscopy was used to study the surface morphology and elemental compositions. X-ray photoelectron spectroscopy (XPS) analysis of the optimized sample provides the bonding state of the compositions. Under 257 nm CTB excitation, the photoluminescence emission spectra (PL) exhibit all the characteristic emission peaks of Pr3+ ion. The transitions involved in the excitation and emission process have been shown in the energy level diagram of Pr3+ ions. The Concentration quenching effect was explained from Bless relation and Dexter energy transfer theory between activator ions. Decay curves of the prepared phosphors show bi-exponential behavior. The up-conversion emission spectra were recorded under 980 nm laser excitation. The optical transition in the UV–Vis range was investigated based on the diffuse reflectance spectra, and the results match well with the excitation spectra. The photometric study informs the color and the quality of the emitted light. The outcomes produce a new synthesis method to prepare La2Zr2O7:Pr3+ nano phosphor that can be an excellent candidate for solid-state lighting and UV/NIR to the visible converter in solar cell applications.

Investigation of structural, photoluminescence, and thermoluminescence properties of Praseodymium doped CaWO4 phosphor

The structural, optical, photoluminescence and thermoluminescence behaviors of Praseodymium doped CaWO4 (Ca1−xPr2x/3WO4; x = 0.01, 0.02, 0.03, 0.04, 0.05) phosphors prepared via conventional solid-state reaction route were reported in this paper. X-ray diffraction study revealed the fact that all the synthesized samples crystallize in a tetragonal structure with I41/a (88) space group and the structural parameters were obtained from the Reitveld refinement. The unit cell volume was found to rise with the increase in Pr concentration. The bandgaps of the prepared samples were obtained from the UV-Visible absorbance spectra by using the Wood-Tauc method. Bandgap and unit cell volume of the prepared samples were directly proportional to each other. Photoluminescence behaviors were investigated from the excitation and the emission spectra. The PL spectra highlight that the quenching occurs at x = 0.02 and the critical distance for energy transfer of the phosphor was found to be 20 Å. Dexter theory was applied to determine the mechanism of quenching and confirmed that the concentration quenching was caused by the dipole-dipole interaction. CIE Chromaticity denoted that the phosphors emit red color. Color purity and CCT of the material were calculated. Thermoluminescence behaviors were studied with different durations of UV dose for the composition x = 0.02 and the kinetic parameters were calculated. Variations of TL emission intensity with temperature confirmed the second-order kinetics of the phosphor with a critical quenching concentration at x = 0.02.

Assessing source and maturity of oils in the Mahu sag, Junggar Basin: Molecular concentrations, compositions and carbon isotopes

Molecular parameters are both facies and maturity dependent. Source and maturity assessment remains a difficult task for oils which were derived from multiple source rocks at a wide range of maturities from the early to late oil generation window. In this paper, a new approach was presented to assess oil source on the basis of molecular facies parameters under maturity constraint using crossplots of one source parameter versus one maturity parameter. Concentrations of ΣC29 steranes and C30 hopane were tentatively used as maturity indicators. Quantitative GC, GC-MS and GC-IRMS analyses were performed on 52 oils from the southern and central Mahu sag of northwestern Junggar Basin, NW China. The 52 oils are first classified into three groups, i.e., groups I, II and III which were derived from source beds within the Lower Permian Fengcheng Formation (P1f), Middle Permian Lower Wuerhe Formation (P2w) and both, respectively on the basis of carbon isotopes of individual n-alkanes in combination with reservoir geological settings. These three oil groups, in particular groups I and II from different sources were further distinguished sufficiently using crossplots of ratios of pristane (Pr)/n-C17 and phytane (Ph)/n-C18, β-carotane/n-C21 and concentrations of n-alkanes, Pr, Ph, β-carotane, Ts, C29 Ts, C30 diahopane, C20, C21 and C23 tricyclic terpanes versus concentrations of ΣC29 steranes and C30 hopane, respectively. Variation trends of isotopic reversal index (RI) and δ13C value of n-C25, the lowest among those of n-alkanes (n-C12–34), with decreasing concentrations of ΣC29 steranes and C30 hopane demonstrate that carbon isotopes of n-alkanes were unlikely influenced significantly by oil maturities within oil generation window. Concentration of n-alkanes increases while concentrations of Pr, Ph, crotanes, terpanes and steranes generally decrease with decreasing concentrations of ΣC29 steranes and C30 hopane. Application of this approach provides numerous choices and opportunities to distinguish oil groups which were derived from different sources in combination with isotopic data and reservoir geological settings.

Optimizing the oxide support composition in Pr-doped CeO2 towards highly active and selective Ni-based CO2 methanation catalysts

In this study, Ni catalysts supported on Pr-doped CeO2 are studied for the CO2 methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated. It is shown, that Pr3+ ions can substitute Ce4+ ones in the support lattice, thereby introducing a high population of oxygen vacancies, which act as active sites for CO2 chemisorption. Pr doping can also act to reduce the crystallite size of metallic Ni, thus promoting the active metal dispersion. Catalytic performance evaluation evidences the promoting effect of low Pr loadings (5 at% and 10 at%) towards a higher catalytic activity and lower CO2 activation energy. On the other hand, higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population, thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.

Spectral analysis of 1G4 level in the Pr3+:YLF crystal

The spectral measurement and energy level analysis of 1G4 are performed. Based on the absorption characteristics of the 1G4 level with different concentrations of Pr3+:YLF，the modified J-O theory was introduced to calculate the main spectral parameters. The emission cross-section spectra with two polarizations of the 1G4→3H5 transition excited by 1028 nm pumping and the fluorescence lifetime at the target wavelength (1322 nm) were measured. At the doping concentration of 1.0 at.%, the calculated peak emission cross section is close to the order of ∼1 × 10−20 cm2. Furthermore, we also discuss the energy level scheme of 1G4 in detail and proposed a cascade mechanism，which allows to further improve the output performance of the 915 nm (3P0→1G4) laser. For the first time, we propose a new approach to generate the fluorescence of 1322 nm by using 1G4 as an upper level.