Optical emission properties of Nd3+ in NaBi(WO4)(2) single crystal

Room temperature optical absorption measurements of Nd3+ in NaBi(WO4)2 single crystals grown by the Czochralski method have been used to calculate the following Judd-Ofelt intensity parameters: Omega2 =30.9 × 10-20 cm2, Omega4 = 12.0 × 10-20 cm2 and Omega6 =9.3 × 10-20 cm2. Using these parameters the emission properties of Nd3+ in this host have been estimated with particular attention to the 4F3/2 energy level responsible for stimulated emission channels. The experimental branching ratios of this level are obtained from photoluminescence and agree with those calculated using the above Omegak parameters. The 4F3/2 emission has negligible non-radiative intrinsic losses and the 10 K lifetime at low Nd concentration, 0.9× 1018 cm-3, is tauexp= 143 mus. Even at 300 K and for a much higher Nd concentration, 4.0× 1019 cm-3, non-radiative losses are moderate, giving a quantum efficiency eta ap 0.85. The 4F3/2 emissions show a strongly polarized character. The largest emission cross-section occurs at lambda =1060.9 nm for the 4F3/2 rarr4I11/2 laser channel with a pi-polarized character, sigmaEMI= 16× 10-20 cm2.This work is supported by the Ministerio de Ciencia y Tecnologıa(MCy T) in Spain, under project the MAT2002-0463-C05-05. V. Volkov acknowledges support by a NATO grant. A. Mendez-Blas is supported by CONACYT (Mexico), grant No. 128118.Peer reviewe

Materiales microporoso germanatos, como catalizadores

Referencia OEPM: P9900953.-- Fecha de solicitud: 07/05/1999.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).Materiales microporoso germanatos, como catalizadores. Compuestos que cristalizan en el sistema ortorrómbico. Se han obtenido por síntesis hidrotermal en un reactor revestido de teflón por reacción de una mezcla de GeO2, Cu(NO3)2.H2O o Ag(NO3), amoniaco, agua y etilenglicol, en relación molar 1:0.1:2:2:0.1, con adición de propilamina y piridina 0.3:1, para el compuesto de Cu. Estos compuestos son catalizadores para la ciclopropanación de olefinas con etil diazoacetato.Peer reviewe

Structural and magnetic characterization of ordered Sr2LnSbO6 (Ln=rare earth) perosvkite

The double perovskites A2LnMO6 (A = Sr2+ and Ba2+; Ln = trivalent lanthanide cation; M = pentavalent 4d or 5d transition elements) have been widely studied concerning their structure and properties [1]. If the Ln and M cations are ordered within the B-perosvkite sites the symmetry and size of the unit cell change when are compared to the ideal cubic aristotype. Woodward predicted 15 possible space groups for the ordered A2BB’O6 perovskites when the cation ordering and the octahedral tilting around the pseudo-cubic axes take place simultaneously [2]. The ordered double perovskites A2LnMO6 with only one of the two B-sites carrying magnetic moment, namely Ln, show a magnetic sublattice consisting of edge-sharing tetrahedral, which represents a frustrating magnetic geometry in three dimensions. More recently, the structure of double perovskites Sr2LnSbO6 (Ln= Dy, Ho, Gd, Y and In) has been investigated, and the monoclinic symmetry of the space group P21/n, with Ln and Sb elements ordered in the B-sites, was reported [3, 4]. We report the preparation of the whole family of double perovskites Sr2LnSbO6 (Ln = La-Lu), which crystallize with the P21/n space group, with lattice parameters p= a2a , p= a2b and p= a2c(β∼90 º), being the lattice parameter of the cubic aristotype. A progressive decreasing was observed in lattice parameters with the increasing of the atomic number of the Ln cation, according with the wellknown lanthanide contraction. pa Magnetic susceptibility measurements for this family of compounds reveal a paramagnetic behaviour in a very wide temperature range. From experimental spectroscopic data as well as from a semi-empirical estimation (Simple Overlap Model SOM [5]) of the crystal-field parameters corresponding to the point site symmetry of the magnetically active Ln, Oh, and using the wavefunctions associated with the energy levels obtained, the paramagnetic susceptibility and its evolution vstemperature is simulated according to the van Vleck formalism. The observed deviation from the Curie–Weiss behaviour at low temperature, very well reproduced in each case, reflects the splitting of the ground state of the corresponding Ln cation under the influence of the crystal field. Thus, magnetic frustration or cooperative interactions do not need to be considered to explain the mentioned low temperature deviation from the linearity of Curie-Weiss plots

NUEVOS CASOS TERATOLÓGICOS EN APOIDEA (HYMENOPTERA)

This work deals with three teratological specimens of Apoidea that belong to the families Halictidae, Anthophoridae and Apidae and the genera Lasioglossum Curtis, 1833, Nomada Scopoli, 1770 and Bombus Latreille, 1802. According to BALAZUC (1948, 1958) these cases are local and preimaginal abnormalities produced in gaster segmentation, in two of the specimens, and in the third the malformations appear in head and the mesothoracic legs. Every possible ethiology is studied too.Se estudian varias conformaciones teratológicas que afectan a tres individuos de la superfamilia Apoidea, pertenecientes a las familias Halictidae, Anthophoridae y Apidae y que corresponden a los géneros Lasioglossum Curtis, 1833, Nomada Scopoli, 1770 y Bombus Latreille, 1802. De acuerdo con BALAZUC (1948, 1958), tales alteraciones se clasifican dentro de las anomalías locales preimaginales: en dos de los ejemplares se trata de errores en la segmentación del gáster y en el tercer ejemplar las malformaciones afectan a la cabeza y patas mesotorácicas. Se indica, asimismo, la posible etiología de estas particularidades morfológicas

Tunable continuous wave and femtosecond mode-locked Yb3+ laser operation in NaLu(WO4)2

7 pages, 13 figures, 3 tables.-- PACS: 42.55.Rz; 42.60.By; 42.60.FcContinuous wave and femtosecond mode-locked laser operation of Yb3+ in the tetragonal NaLu(WO4)2 crystal host is demonstrated by pumping with a Ti:sapphire laser. Pumping with 1.8 W at 974 nm, a maximum output power of 650 mW was achieved at 1029.6 nm. The slope efficiency was in excess of 60%. The laser performance was similar for the two polarizations. By inserting a birefringent filter the output wavelength was tunable from 1010 to 1055 nm. Pulses as short as 90 fs with an average power of 50 mW were generated by passive mode locking at a repetition rate of 95 MHz. These attractive laser properties of NaLu1−xYbx(WO4)2 are related to the inhomogeneous broadening of the Yb3+ spectral features resulting from the local disorder of the host crystal. We report the spectroscopic properties of Yb3+ in the 5–300 K temperature range and the optical properties of the host at room temperature.This work was supported by Projects Nos. NMP3-CT- 2003-505580 (EU), MAT2004-21113E, and MAT2005-6354- C03-01 (Spain). A.G. (FPU2003-018), X.H. (JC12006-4015-2459) and X.M. (EX2004-1294) are supported by grants from the Spanish government. X.M. additionally acknowledges support from the European Science Foundation.Peer reviewe

Tunable continuous wave and femtosecond mode-locked Yb3+ laser operation in NaLu(WO4)2

7 pages, 13 figures, 3 tables.-- PACS: 42.55.Rz; 42.60.By; 42.60.FcContinuous wave and femtosecond mode-locked laser operation of Yb3+ in the tetragonal NaLu(WO4)2 crystal host is demonstrated by pumping with a Ti:sapphire laser. Pumping with 1.8 W at 974 nm, a maximum output power of 650 mW was achieved at 1029.6 nm. The slope efficiency was in excess of 60%. The laser performance was similar for the two polarizations. By inserting a birefringent filter the output wavelength was tunable from 1010 to 1055 nm. Pulses as short as 90 fs with an average power of 50 mW were generated by passive mode locking at a repetition rate of 95 MHz. These attractive laser properties of NaLu1−xYbx(WO4)2 are related to the inhomogeneous broadening of the Yb3+ spectral features resulting from the local disorder of the host crystal. We report the spectroscopic properties of Yb3+ in the 5–300 K temperature range and the optical properties of the host at room temperature.This work was supported by Projects Nos. NMP3-CT- 2003-505580 (EU), MAT2004-21113E, and MAT2005-6354- C03-01 (Spain). A.G. (FPU2003-018), X.H. (JC12006-4015-2459) and X.M. (EX2004-1294) are supported by grants from the Spanish government. X.M. additionally acknowledges support from the European Science Foundation.Peer reviewe

Effectiveness of Exercise on Fatigue and Sleep Quality in Fibromyalgia: A Systematic Review and Meta-analysis of Randomized Trials

Objectives: To determine the effects of exercise on fatigue and sleep quality in fibromyalgia (primary aim) and to identify which type of exercise is the most effective in achieving these outcomes (secondary aim). Data Sources: PubMed and Web of Science were searched from inception until October 18, 2018. Study Selection: Eligible studies contained information on population (fibromyalgia), intervention (exercise), and outcomes (fatigue or sleep). Randomized controlled trials (RCT) testing the effectiveness of exercise compared with usual care and randomized trials (RT) comparing the effectiveness of 2 different exercise interventions were included for the primary and secondary aims of the present review, respectively. Two independent researchers performed the search, screening, and final eligibility of the articles. Of 696 studies identified, 17 RCTs (nZ1003) were included for fatigue and 12 RCTs (nZ731) for sleep. Furthermore, 21 RTs compared the effectiveness of different exercise interventions (nZ1254). Data Extraction: Two independent researchers extracted the key information from each eligible study. Data Synthesis: Separate random-effect meta-analyses were performed to examine the effects from RCTs and from RTs (primary and secondary aims). Standardized mean differences (SMD) effect sizes were calculated using Hedges’ adjusted g. Effect sizes of 0.2, 0.4, and 0.8 were considered small, moderate, and large. Compared with usual care, exercise had moderate effects on fatigue and a small effect on sleep quality (SMD, e0.47; 95% confidence interval [CI], e0.67 to e0.27; P<.001 and SMD, e0.17; 95% CI, e0.32 to e0.01; PZ.04). RTs in which fatigue was the primary outcome were the most beneficial for lowering fatigue. Additionally, meditative exercise programs were the most effective for improving sleep quality. Conclusions: Exercise is moderately effective for lowering fatigue and has small effects on enhancing sleep quality in fibromyalgia. Meditative exercise programs may be considered for improving sleep quality in fibromyalgi

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Investigation of site-selective symmetries of Eu3+ ions in KPb2Cl5 by using optical spectroscopy

Site-selective time-resolved spectroscopy of Eu3+ in KPb2Cl5 has been investigated by using fluorescence line narrowing technique. A crystal field analysis and simulation of the experimental results has been performed in order to parametrize the crystal field at the Eu3+ sites. Three symmetry independent crystal field sites for the rare-earth ion in this crystal were found. A plausible argument about the crystallographic nature of these sites is given.This work was supported by the Spanish Government MEC (MAT2004-03780 and MAT2004-02001) and Basque Country University (UPV13525/2001).Peer reviewe

Tunable upconverted visible light and high sensitivity optical thermal sensing of Ln, Yb:Y6O5F8 nanotubes

Paper presented at the 15th European Conference on Solid State Chemistry (2015) held in Vienna (Austria), 23-26th August, 2015.Micron-sized bundles of highly crystalline individual nanotubes of Pbcm Vernier-type Yb3+-sensitized Ln3+ (Er, Pr)-doped Y6O5F8 oxyfluorides have been prepared through efficient low-temperature hydrothermal syntheses. Under near infrared (NIR) 978 nm diode laser excitation, the color of the upconverted light from codoped Pr, Er, Yb:Y6O5F8 nanotubes can be selected by the control of the Pr3+ concentration, and by the excitation regime and power density. Samples with low Pr3+ concentration emit predominantly green light, and the selection between bluish-green light and white light has been demonstrated with large Pr3+ concentration (2 mol%), under pulsed or continuous wave excitation, respectively. Involved Er3+ and Pr3+ electronic transitions and mechanisms to populate their corresponding emitting levels have been analyzed for a large number of 2 mol% Yb3+-sensitized, 0.05 mol% Er3+-doped oxyfluoride samples within the Pr3+ concentration span 0.2 - 2 mol% [1]. Furthermore, the ratiometric analysis of the thermal evolution of intensities of NIR excited green upconverted emissions from thermally coupled 2H11/2 and 4S3/2 Er3+ multiplets of Er, Yb:Y6O5F8 indicates thermal sensing potential with better sensitivity S (0.0041 KK-1) than hexagonal Er, Yb:beta-NaYF4(0.0032 K-1) in the temperature range of physiological interest.Work supported by the Spanish Ministry of Economy and Competitiveness and by the European Regional Development Fund through MAT2011-29255-C02-01 and MAT2014-56607-R projects