Multisite Structure Research Articles

Spectroscopy and Kerr-lens mode-locked operation of Yb:GdScO3 crystal

A Kerr-lens mode-locked laser based on a Yb3+-doped disordered gadolinium scandate (Yb:GdScO3) crystal is reported for the first time, to the best of our knowledge. The crystal with the perovskite structure was grown using the Czochralski method, and its room temperature (RT) and low temperature (LT) spectra were also investigated. Due to the crystal's multisite structure (Gd3+/Sc3+ site), Yb:GdScO3 offers broad and intense polarized emission spectra in the near-infrared range (975–1075 nm). The stimulated emission cross section σSE is 0.46 × 10−20 cm2 at 1000 nm with an emission band width of 75.7 nm for E // b polarization. The continuous wave (CW) laser was operated pumped by a 976 nm fiber-coupled LD laser, resulting in a maximum output power of 8.74 W with a slope efficiency of 76.1% was obtained. Additionally, a pulses as short as 74 fs are generated at ∼1061.7 nm via Kerr-lens mode-locking. The average output power amounts to 32 mW at a pulse repetition rate of 101.4 MHz. All results indicate Yb:GdScO3 a promising candidate for 1 µm ultrashort laser.

Tunable and mode-locked Tm,Ho:GdScO3 laser.

A novel, to the best of our knowledge, Tm,Ho:GdScO3 crystal grown using the Czochralski method was investigated for its polarized spectroscopic properties and laser performance in both tunable continuous-wave (CW) and mode-locked regimes. The crystal's multisite structure (Gd3+/Sc3+ site) and Tm3+/Ho3+ dopants contributed to spectral broadening, enabling a tunable laser operation from 1914 to 2125 nm (with a broad range of 215 nm). Additionally, a pulse duration of 72 fs was achieved for E || b polarization. These results demonstrate the potential of the Tm,Ho:GdScO3 perovskite crystal as a promising gain material for ultrafast lasers operating around 2 µm.

Luminescence enhancement of Cr3+ doped garnet phosphor for high-performance LED towards smart NIR light source

Cr3+ doped phosphor shows great potential for near-infrared (NIR) light-emitting diodes (LED), but it suffers from low quantum efficiency and poor thermal stability. Herein, a novel Cr3+ doped broadband NIR garnet Ca3Sc2Ge3O12 phosphor was developed. The multisite structure of the emission band is investigated by site-selective spectroscopy and is attributed to the octahedral Cr3+ perturbed by defects. Moreover, we propose different strategies to enhance the luminescence of the phosphor, including enhancement of crystallinity and elimination of defects. Compared with the initial sample, the emission intensity of the optimized phosphor is improved for 8.6 times. The optimal Ca3Sc2Ge3O12: 0.06Cr3+ phosphor exhibits excellent thermal stability. At 423 K, the integral emission intensity of the optimal sample remains 94.7% of that at room temperature. Finally, high-performance NIR LED was fabricated using a blue LED and the title phosphor. The packaged LED lamp has high radiance (109.3 mW@300 mA) and photoelectric efficiency (15.96%@40 mA). Our study not only provides a boulevard for enhancing the luminescence of Cr doped NIR phosphor, but also gives a new perspective for understanding the multisite luminescence of Cr3+ in garnet host.

Metalloporphyrin and triazine integrated nitrogen-rich frameworks as high-performance platform for CO2 adsorption and conversion under ambient pressure

The development of multi-site integrated nanomaterials with remarkable properties and their application to selective CO2 capture and utilization have attracted extensive research interest. In this study, several metalloporphyrin and triazine integrated nitrogen-rich frameworks (M ⊂ PPTFs; where “M” stands for metal) were constructed and structurally characterized. These frameworks’ tendency to adsorb CO2 and their catalytic performance in the conversion of CO2 to cyclic carbonates were then investigated. The cycloaddition between CO2 and epichlorohydrin to produce chloropropene carbonate was selected as model reaction to screen the various catalysts and optimize the reaction conditions. The recycling performance and substrate scope were also evaluated. Evidence indicated that Zn ⊂ PPTF15 has dual functions: CO2 adsorption and its synergistic conversion. The CO2 adsorption capacity reached values of 2315 μmol/g and 1883 μmol/g at 273 K and 298 K, respectively. Under conditions of synergistic catalysis with tetrabutylammonium bromide (TBAB), Zn ⊂ PPTF15 afforded 96% yield of chloropropene carbonate with 99% selectivity at 60 °C and 0.1 MPa CO2 pressure for 15 h. The catalytic conditions and activity were investigated by comparison with reported triazinyl-based polymers. Notably, the catalytic system also displayed satisfactory applicability to other epoxides. Furthermore, Zn ⊂ PPTF15 was easily recyclable and did not become deactivated after repeated use. Based on the multi-site structure of the catalyst and the experimental results, a possible mechanism was proposed for the cycloaddition reaction.

"Trying to develop a better workforce": Stakeholders' perspectives of a practice-integrated Australian hospital pharmacist foundation residency program.

BackgroundPractice-integrated education and professional development programs (also known as residencies), have been available to pharmacists in America and the United Kingdom for many years. In 2016, the Society of Hospital Pharmacists of Australia launched Australia’s novel Foundation Residency Program to support the development of early-career pharmacists, and has been implemented across many hospitals nationally. This model was adopted by the South Australian (SA) public hospital pharmacy statewide service and was granted full accreditation. The study aimed to explore key stakeholders’ expectations and early perceptions of the structure, role and impact of the SA program and in that process, to identify key influencing factors and strategies informing future program planning and design.MethodsPurposeful sampling was adopted to recruit participants who oversee preceptors and residents, across all employment levels and pharmacy service sites. Stakeholders participated in individual semi-structured interviews. Each interview was audio-recorded and transcribed verbatim. The transcribed dataset was managed using NVivo softwareTM (version 10) and analysed using reflexive thematic analysis through the lens of the PRECEDE-PROCEED logic model framework.ResultsThirty-three staff consented to participate. Participants were de-identified with a randomly assigned code number. Three key themes were identified using reflexive thematic analysis; alignment of program goals and visions, culture shift to prioritising workforce development as core business, program structure supports focused workforce development.ConclusionsParticipants view the residency as beneficial for development of the residents, preceptors, and the hospital pharmacy workforce. The multisite structure was a strength of the program. Whilst it was acknowledged that the rotations, cross-site rotations, and research project presented challenges, they were deemed worth the investment. Overall, it was felt that incremental increases in program capacity will occur over time, as culture changes, and as investing in workforce development becomes core business. The findings have led to several key recommendations to guide program expansion.

Global Christianity as Method: Reorienting the Study of American Mega- and Multisite Churches

Scholarship in global Christianity has brought greater attention to understudied and/or marginalized Christian communities beyond the Euro-Atlantic. However, work within the subfield has also unwittingly reproduced colonial tropes and hierarchies in its approach to the study of non-Western Protestant communities. For example, scholarship on megachurches has largely echoed the narrative that non-Western megachurches are reproductions and/or adaptations of originally American ecclesial forms. This article argues that the subfield’s decolonial aims are better served by taking global Christianity as a methodological approach offering particular attention to translocal circulations of ideas and practices, especially circulations that challenge the self-sufficiency of the West and its cultural forms. Employing this approach, this article indicates that American megachurches are not always the “crucible” of global trends, contrary to prevailing narratives. American megachurches followed the example of South Korean megachurches in adopting both the multisite church structure and cell groups. Tracing American megachurch practices through their transnational histories challenges the American exceptionalism within certain accounts of megachurches and demonstrates how scholars might present marginalized Christianities differently by adopting a broader understanding of global Christianity and where it may be observed.

Fatigue Reliability Analysis of a Compressor Disk Based on Probability Cumulative Damage Criterion.

The reliability of aero engine has a direct impact on the flight safety of the whole plane. With the continuous improvement of performance requirements of aero engines, the related fatigue and reliability problems also appear. For the fatigue failure characteristics of the typical component (compressor disk) in an aero engine, the fatigue reliability of its multi-site damage structure in service is analyzed by using probability cumulative damage criterion in this paper. The probability distribution definitions of life, damage and damage threshold are discussed and the relationship among them is also introduced by the new proposed criterion. Meanwhile, a method to determine the probability distribution of cumulative damage threshold and probability life prediction is carried out, based on which a hierarchical index system of statistical analysis and reliability modeling principle on the system level is further constructed for compressor disk. At the end of the paper, a certain cruise of fighter plane is analyzed to verify the validity of the new model. Emphasizing the difference between the compressor disk and traditional component, the new reliability analysis model developed in this study is basically reasonable for most of the load histories for the compressor disk, other than the traditional one, especially for the changeable and complex cruise missions.

German Cancer Consortium (DKTK) - A national consortium for translational cancer research.

The German Cancer Consortium (‘Deutsches Konsortium für Translationale Krebsforschung’, DKTK) is a long‐term cancer consortium, bringing together the German Cancer Research Center (DKFZ), Germany's largest life science research center, and the leading University Medical Center‐based Comprehensive Cancer Centers (CCCs) at seven sites across Germany. DKTK was founded in 2012 following international peer review and has positioned itself since then as the leading network for translational cancer research in Germany. DKTK is long term funded by the German Ministry of Research and Education and the federal states of each DKTK partner site. DKTK acts at the interface between basic and clinical cancer research, one major focus being to generate suitable multisite cooperation structures and provide the basis for including higher numbers of patients and facilitate effective collaborative forward and reverse translational cancer research. The consortium addresses areas of high scientific and medical relevance and develops critical infrastructures, for example, for omics technologies, clinical and research big data exchange and analysis, imaging, and clinical grade drug manufacturing. Moreover, DKTK provides a very attractive environment for interdisciplinary and interinstitutional training and career development for clinician and medical scientists.

Identification of dual luminescence centers from a single site in a novel blue-pumped Ca3Sc2Ge3O12:Ce3+ phosphor.

The luminescence spectra of some trivalent rare-earth ions in a garnet host present interesting multisite structures; however, their mechanism is still not fully understood. In this study, for the first time, we directly observed two luminescence centers of Ce3+ at a single site in a novel garnet Ca3Sc2Ge3O12 phosphor. The spectral characteristics of the two luminescence centers were clearly identified using site-selective and time-resolved spectroscopy. Luminescence excitation was observed at 425 nm and 450 nm, corresponding to emissions at 490 (Ce(i)) nm and 530 (Ce(ii)) nm. The decay curves confirmed the existence of energy transfer from Ce(i) to Ce(ii). The potential mechanisms of the multisite luminescence are also discussed. This study gives a new insight into the concentration-dependent red-shift and inhomogeneous broadening of the Ce3+ emission band in the garnet phosphor. The title phosphor showed excellent thermal stability, with more than 90% of the initial intensity at the functioning temperature (323 K). Finally, a white LED lamp was fabricated, which exhibited an excellent color rendering index (82.3) and a proper correlated color temperature (3582 K). These results demonstrate that Ca3Sc2Ge3O12:Ce3+ is highly promising to serve as a blue-pumped phosphor for white LEDs.

Anti‐Stokes cooling of Yb-doped KYF4 single crystals

Truly vibration-free, optical cooling of solids, relying on annihilation of lattice phonons via anti-Stokes fluorescence, is a rapidly advancing technology with a huge potential impact on a variety of space and terrestrial applications. In this paper, we focus on investigation of active media and we report on the first observation of anti-Stokes cooling in a novel material, a Yb-doped KYF4 single-crystal, promising in relation to its multi-site structure and low phonon cut-off energy. The cooling efficiency of the sample was measured, external quantum efficiency and background absorption were evaluated and compared to other fluoride active media. Bulk cooling by ~ 1.8 °C was observed under ~ 1.5 W laser excitation, tuned close to 1025 nm, in single-pass configuration.

Judd-Ofelt analysis of Er-doped CaSc2O4 revisited

The Judd-Ofelt analysis of Er3+ in CaSc2O4, presented by the same authors in 2015, is revisited using recently published data concerning the dispersion of the refractive index and taking into account the multisite structure of the luminescent centers. The new Judd-Ofelt parameters are Ω2 = 3.42 × 10–20 cm2, Ω4 = 1.66 × 10–20 cm2, and Ω6 = 0.76 × 10–20 cm2. The energy gap necessary to calculate the common radiative lifetime of the thermalized levels (2H11/2, 4S3/2) was measured in a Fluorescence Intensity Ratio experiment and is ΔE = 816 cm−1. We obtained τrad(2H11/2, 4S3/2) = 399 µs and τrad(4F9/2) = 390 µs. The recalculated quantum efficiencies are 0.30 for (2H11/2, 4S3/2) and 0.17 for 4F9/2.

(Invited) Studies of Luminescence Efficiency of BaWO4:Ce Crystals

Barium tungstate crystals are interesting and relatively new medium for stimulated Raman scattering for applications in Raman shifters of laser radiation [1]. Good quality BaWO4 crystals can be grown by Czochralski technique and doped with rare-earth ions. Doping with trivalent ions require charge compensation which may be provided, for example, by structural defects or proper codoping with alkaline metal ions. Crystals posses sheelite structure with the space group I41/a. Results of studies of BaWO4:Ce crystals and crystals codoped with Na are presented in this work. Optical absorption in the vis-UV and infrared range and Raman spectra has been studied. In the UV the crystals shows typical absorption for Ce3+ with two bands peaked at 320 nm and 285 nm, which are associated with lowest energy 4f-5d transitions. However only very weak Ce3+ luminescence is observed even at 10 K, contrary to some reports on this subject [2]. In the mid-infrared range several absorption bands are visible which may be associated with lattice absorption. Besides of lines associated with single TO phonon modes in the range up to 1000 cm-1 the additional lines appear around 1700 cm-1 and 2600 cm-1. Origin of these lines is discussed in this work. Raman spectra at room temperature show very sharp lines with the highest energy line at 927 cm-1. Some additional much broader lines are observed above 1200 cm-1 [3]. Their origin is most probably associated with combination of various phonon modes. In addition to that very sharp lines due to the 4f-4f transitions in the Ce3+ ions are visible around 2200 cm-1 and 2350 cm-1. There are at least four of these lines in each group which are related to the multisite structure of RE doping in these crystals. The crystal field analysis allows identifying nature of these lines. The transitions associated with Ce3+ ions are very strongly coupled with the lattice and they undergo very important broadening with increase of temperature. This is explained as a result of electron-phonon coupling, enhanced by the matching inter-level spacing of the 2F7/2 state with phonon energies. BaWO4 has the largest energy gap among several tungstates with scheelite structure [4]. It is in good agreement with the values of ionic radii of cations constituting the host. The conduction band is dominated by the W6+ 5d states. On the other hand the luminescence efficiency of Ce3+ dopand in BaWO4 is the lowest among the (Ca, Sr,­ Ba)WO­4, which have smaller band-gap than BaWO4. It may be associated with resonant position of the lowest 5d state of Ce3+ in the conduction band or with the thermally activated crossover between the 4f 5d state and the 4f states. The large band gap of BaWO4 rather shows that the latter mechanism is operative as the luminescence quenching mechanism. High pressure luminescence studies in diamond anvil cell, which should help to resolve this question will be presented in this work. Acknowledgements: This work was supported by the Polish National Science Center (project 2015/17/B/ST5/01658)

Differences in Case Conferences in Dementia Specific vs Traditional Care Units in German Nursing Homes: Results from a Cross-Sectional Study

ObjectivesTo investigate differences in the provision and performance of case conferences for people with dementia between dementia special care units (DSCUs) and traditional care units (TCUs) in nursing homes. Because DSCUs employ more staff, we expect the likelihood of the provision of case conferences to be higher in DSCUs. DesignObservational cross-sectional study. Residents from DSCUs and TCUs were compared using genetic propensity score matching over all of the observed potential covariates, including the characteristics that served as admission criteria for DSCUs. Because of the multisite structure of the data, clustering was accounted for with a generalized mixed model. SettingDSCUs are defined as units within nursing homes that offer care exclusively to residents with dementia and that charge higher rates for the specialized care provided. TCUs are defined as care units for residents with and without dementia. ParticipantsA matched sample was drawn out of a convenience sample of 1808 residents from 51 nursing homes. It consisted of 264 residents from 16 DSCUs and 264 residents from 48 TCUs. InterventionsNone. MeasurementsData regarding the provision of case conferences were collected by the nurses using the Dementia Care Questionnaire. Other collected data included challenging behavior (Neuropsychiatric Inventory Questionnaire), mobility (Physical Self-Maintenance Scale), cognitive impairment (Dementia Screening Scale), and sociodemographic information. ResultsIn the DSCU group, case conferences were provided to 91% (n = 224) of the residents; in the TCU group, 82.5% (n = 203) received a case conference. After adjusting for clustering, no significant difference between DSCUs and non-DSCUs was found. The topic “challenging behaviors” was discussed more often in case conferences in TCUs. ConclusionsCase conferences are a widespread intervention in German nursing homes, including both DSCUs and TCUs. The provision of a case conference is not a special feature of DSCUs.

Optimisation of distributed maintenance: Modelling and application to the multi-factory production

This paper concerns the modelling and the cost evaluation of maintenance activities in a distributed context. In this work we study the particular case where the maintenance activities are executed by two workshops: a central maintenance workshop (CMW) and a mobile maintenance workshop (MMW). The CMW concerns the repairing process for the corrective maintenance and the MMW executes all preventive maintenance in several factories according to a defined scheduling. The aim is to take into account the resources (spare parts in the MMW) and maintenance actions for a given operating budget. A modular approach for modelling a multi-site structure is proposed to achieve the aim of improving the availability of facilities on production sites while minimising the cost of maintenance.

Spectroscopic analysis of Nd^3+: Gd_3Al_xGa_5−xO_12 garnet crystal

We report a complete spectroscopic analysis of Nd3+-doped Gd3AlxGa5−xO12 garnet crystal (Nd:GAGG), including absorption and emission spectra at low and room temperatures, excitation spectra showing the multisite structure of the host crystal, and temperature dependence of the lifetime of the F324 manifold. We also report the emission cross sections for the transitions from the F324 manifold and a Judd–Ofelt analysis with the calculation of the spontaneous emission probabilities and the radiative branching ratios.

Assessing the impact of climate change on basin-average annual typhoon rainfalls with consideration of multisite correlation

The effects of climate change on synoptic scale storms like typhoons can have profound impacts on practices of water resources management. A stochastic multisite simulation approach is proposed for assessing the impact of climate changes on basin-average annual typhoon rainfalls (BATRs) under certain synthesized climate change scenarios. Number of typhoon events and event-total rainfalls are considered as random variables characterized by the Poisson and gamma distributions, respectively. The correlation structure of event-total rainfalls at different rainfall stations is found to be significant (higher than 0.80) and plays a crucial role in the proposed stochastic simulation approach. Basin-average annual typhoon rainfalls were simulated for the Shihmen Reservoir watershed in northern Taiwan by considering changes in the mean values of annual number of typhoon events and event-total rainfalls, while assuming the correlation structure of multisite typhoon rainfalls to remain unchanged. The simulation results indicate that changes in expected values of BATR can be easily projected with simpler models; however, changes in extreme properties of BATR are more complicated. Comparing to changes in expected values of BATRs, lesser changes in more extreme events can be observed. This is due to the reduction in coefficient of skewness of gamma distribution BATR under different climate change scenarios. With consideration of the multisite correlation structure, changes in BATRs become more significant. Thus, in assessing the impacts of climate change on many hydrological and environmental variables which exhibit significant spatial correlation pattern, the multisite correlation structure needs to be taken into consideration.

Multisite Structure and Luminescence Spectra from 4f65d1 → 4(8S7/2) and 4(6P7/2) → 4(8S7/2) Transitions in Eu2+-Doped NaMgPO4

Eu2+-doped NaMgPO4 phosphor was prepared by conventional high-temperature solid-state reaction. The photoluminescence excitation and emission spectra were investigated. The phosphor can be excited by UV-visible light from 220 to 430 nm to realize emission from 4f65d1 → 4(8S7/2) transition in the blue range. The 4(6P7/2) → 4(8S7/2) transition in the 4 electronic configuration of Eu2+ at 360 nm was observed at low temperature. The luminescence absolute quantum efficiency, the crystallographic sites and the microstructure of Eu2+ ions doped in NaMgPO4 lattices were reported. The multiple sites structure of Eu2+ ions in NaMgPO4 lattices was discussed. The luminescence quenching temperatures and the thermal activation energy for NaMgPO4:Eu2+ were obtained from the temperature dependent (18–300 K) luminescence decay curves. Eu2+ ions have the “disordered environment” in NaMgPO4 lattices. The relation between the luminescence thermal stabilities and the crystal structures were discussed.

Conductance of inhomogeneous systems: Real‐time dynamics

AbstractNumerical time evolution of transport states using time dependent Density Matrix Renormalization Group (td‐DMRG) methods has turned out to be a powerful tool to calculate the linear and finite bias conductance of interacting impurity systems coupled to non‐interacting one‐dimensional leads. Several models, including the Interacting Resonant Level Model (IRLM), the Single Impurity Anderson Model (SIAM), as well as models with different multi site structures, have been subject of investigations in this context. In this work we give an overview of the different numerical approaches that have been successfully applied to the problem and go into considerable detail when we comment on the techniques that have been used to obtain the full I–V‐characteristics for the IRLM. Using a model of spinless fermions consisting of an extended interacting nanostructure attached to non‐interacting leads, we explain the method we use to obtain the current–voltage characteristics and discuss the finite size effects that have to be taken into account. We report results for the linear and finite bias conductance through a seven site structure with weak and strong nearest‐neighbor interactions. Comparison with exact diagonalisation results in the non‐interacting limit serve as a verification of the accuracy of our approach. Finally we discuss the possibility of effectively enlarging the finite system by applying damped boundaries and give an estimate of the effective system size and accuracy that can be expected in this case.

The Neuro-Ophthalmology Research Disease Investigator Consortium (NORDIC)

The Neuro-Ophthalmology Research Disease Investigator Consortium (NORDIC)

Discrete solitons and vortices in hexagonal and honeycomb lattices: Existence, stability, and dynamics

We consider a prototypical dynamical lattice model, namely, the discrete nonlinear Schrödinger equation on nonsquare lattice geometries. We present a systematic classification of the solutions that arise in principal six-lattice-site and three-lattice-site contours in the form of both discrete multipole solitons and discrete vortices. Additionally to identifying the possible states, we analytically track their linear stability both qualitatively and quantitatively. We find that among the six-site configurations, the "hexapole" of alternating phases (0-pi) , as well as the vortex of topological charge S=2 have intervals of stability; among three-site states, only the vortex of topological charge S=1 may be stable in the case of focusing nonlinearity. These conclusions are confirmed both for hexagonal and for honeycomb lattices by means of detailed numerical bifurcation analysis of the stationary states from the anticontinuum limit, and by direct simulations to monitor the dynamical instabilities, when the latter arise. The dynamics reveal a wealth of nonlinear behavior resulting not only in single-site solitary wave forms, but also in robust multisite breathing structures.