Lifetime Values Research Articles

Solid-state emissive Zn2+ directed metallo-supramolecular polymers of bis-terpyridine appended aryl substituted buta-1,3-diene derivatives: Synthesis, photo-physical and electrochemical properties

Herein, two solid-state emissive monomers (TBBTP and ABTP) of bisterpyridine (bis-tpy) appended with twisted aryl substituted buta-1,3-diene central core have been designed and developed to investigate metal directed assembly to metallo-supramolecular homopolymers, TBBTP-Zn and ABTP-Zn and a copolymer, ATBBTP-Zn with zinc ion. The formation as well as purities of the monomers have been checked by NMR, FT-IR spectroscopy and mass spectrometry studies and the polymers have been characterised via NMR and FT-IR studies. Prior to optical studies, density functional theory (DFT) studies have been performed to rationalize the electronic distributions in HOMOs and LUMOs of monomers and their corresponding Zn complexes to unveil the phenomenon of intramolecular charge transfer. Absorption and emission studies performed in solution as well as in solid state have indicated that the monomers and its metallo-supramolecular polymers are emissive in solution as well as in solid state. However, the emission maxima at 608 nm, 576 nm and 590 nm of the metallo-supramolecular polymers, TBBTP-Zn, ABTP-Zn and ATBBTP-Zn respectively are clearly red shifted from monomers (466 nm for TBBTP and 490 nm for ABTP) and the fluorescence lifetime values measured by time-correlated single photon counting (TCSPC) are increased in solution as well as in solid state after coordination with Zn2+ ion owing to the charge-transfer processes from the central butadiene part to zinc coordinated terpyridine moiety. The HOMO and LUMO energies, band gaps of monomers (2.95 eV for TBBTP and 2.85 eV for ABTP) and polymers (2.73 eV, 2.84 eV and 2.73 eV for TBBTP-Zn, ABTP-Zn and ATBBTP-Zn respectively) have been estimated via electrochemical methods and it reveals that both monomers as well as polymers may be used in optoelectronic application.

Waking the monster: The onset of AGN feedback in galaxy clusters hosting young central radio galaxies

Aims. The investigation of the feedback cycle in galaxy clusters has historically been performed for systems where feedback is ongoing (“mature-feedback” clusters), that is where the central radio galaxy has inflated radio lobes, pushing aside the intracluster medium (ICM). In this pilot study, we present results from “pre-feedback” clusters, where the central newly active radio galaxies (age < 103 yr) may not yet have had time to alter the thermodynamic state of the ICM. Methods. We analyze Chandra and MUSE observations of two such systems, evaluating the hot gas entropy and cooling time profiles, and characterizing the morphology and kinematics of the warm gas. Results. Based on our exploratory study of these two sources, we find that the hot gas meets the expectations for an as of yet unheated ICM. Specifically, the entropy and cooling time of pre-feedback clusters within 20 kpc from the center fall below those of mature-feedback clusters by a factor ∼2. We speculate that with an estimated mechanical power of ∼1044 − 1045 erg s−1, the two young radio galaxies may restore the entropy levels in a few tens of millions of years, which are typical values of power outbursts and lifetimes for radio galaxies in clusters. Conversely, the properties of the gas at ∼104 K seem to remain invariant between the two feedback stages, possibly suggesting that the warm gas reservoir accumulates over long periods (107 − 108 yr) during the growth of the radio galaxy. We conclude that the exploratory results obtained from our analysis of two cluster-central young radio galaxies are crucial in the context of understanding the onset of active galactic nuclei feedback, and they provide enough motivation for further investigation of similar cases.

Effect of thermal treatment on ZnSe quantum dots and energy transfer in borosilicate glasses doped with ZnSe and Er3+/ZnSe

This study assessed the effect of heat treatment on the spectroscopic properties of borosilicate glasses doped with ZnSe quantum dots (QDs) and co-doped with Er3+/ZnSe. The gradual growth of ZnSe QDs upon heat treatment was probed by TEM. The emission intensity of ZnSe-doped glasses rapidly increased up to 20 h of heat treatment because of the formation and development of ZnSe QDs, then gradually decreased due to the rise in non-radiative loss between the enlarged particles. With increasing number of ZnSe QDs, the energy transfer from QDs to Er3+ ions became prominent in Er3+/ZnSe-co-doped glasses, showing enhanced emission up to 20 h of heat treatment. The excited state 4S3/2 lifetime values, increased with heat treatment, whereas an opposite trend was observed for the lifetime values of state 4I13/2, indicating a possible participation of the ZnSe QDs in facilitating the energy migration mechanism through the 4I13/2 level, followed by non-radiative decay.

Strain and Optoelectronic Tuning in Mixed‐Halide Perovskites with Ion Irradiation

AbstractDefects usually behave as imperfections in materials that significantly degrade their performance. However, the unusual optoelectronic performance in metal halide perovskites in the presence of defects opens the way for strain and optoelectronic properties tailoring with ion irradiation. Defects and strain engineering is performed in triple‐cation mixed halide perovskites using proton irradiation at 1 MeV and different fluences. At intermediate fluence, the initial polycrystalline film compressive strain (−0.15%) can be released, improving exciton lifetimes from about 500 ns to ≈1 µs. In contrast, high irradiation fluence is shown to restore compressive strain leading to sample degradation, with lower lifetime values (≈200 ns). Also, the phase segregation occurring under light illumination between bromine‐rich and iodine‐rich regions is shown to be defects‐mediated as the segregation rate increases by a factor of four for high proton irradiation fluence. The irradiation defects are revealed with low‐temperature photoluminescence (PL) through bound exciton radiative recombination mechanisms. The PL temperature dependence gives some insight into electron–phonon coupling mechanism and their modification with ion irradiation.

Ho3+ doped low-phonon single crystals and chalcogenide glasses for mid-IR source application

A comparative study was conducted to investigate the 3.9 µm mid-IR emission properties of Ho3+ doped NaYF4 and CsCdCl3 crystals as well as Ho3+ doped Ga2Ge5S13 glass. Following optical excitation at ∼890 nm, all the studied materials exhibited broad mid-IR emissions centered at ∼3.9 µm at room temperature. The mid-IR emission at 3.9 µm, originating from the 5I5 → 5I6 transition, showed long emission lifetime values of ∼16.5 ms and ∼1.61 ms for Ho3+ doped CsCdCl3 crystal and Ga2Ge5S13 glass, respectively. Conversely, the Ho3+ doped NaYF4 crystal exhibited a relatively short lifetime of ∼120 µs. Temperature dependent decay time measurements were performed for the 5I5 excited state for all three samples. The results showed that the emission lifetimes of Ho3+:CsCdCl3 and Ho3+:Ga2Ge5S13 were nearly temperature independent over the range studied, while significant emission quenching of the 5I5 level was observed in Ho3+:NaYF4. The temperature dependence of the multi-phonon relaxation rate for 3.9 µm mid-IR emission in Ho3+:NaYF4 crystal was determined. The room temperature stimulated emission cross-sections for all three samples were calculated using the Füchtbauer-Landenburg equation. Furthermore, the results of Judd-Ofelt analysis are presented and discussed.

Fluorescence Lifetime Macro Imager for Biomedical Applications

This paper presents a new photoluminescence lifetime imager designed to map the molecular oxygen (O2) concentration in different phosphorescent samples ranging from solid-state, O2-sensitive coatings to live animal tissue samples stained with soluble O2-sensitive probes. In particular, the nanoparticle-based near-infrared probe NanO2-IR, which is excitable with a 625 nm light-emitting diode (LED) and emits at 760 nm, was used. The imaging system is based on the Timepix3 camera (Tpx3Cam) and the opto-mechanical adaptor, which also houses an image intensifier. O2 phosphorescence lifetime imaging microscopy (PLIM) is commonly required for various studies, but current platforms have limitations in their accuracy, general flexibility, and usability. The system presented here is a fast and highly sensitive imager, which is built on an integrated optical sensor and readout chip module, Tpx3Cam. It is shown to produce high-intensity phosphorescence signals and stable lifetime values from surface-stained intestinal tissue samples or intraluminally stained fragments of the large intestine and allows the detailed mapping of tissue O2 levels in about 20 s or less. Initial experiments on the imaging of hypoxia in grafted tumors in unconscious animals are also presented. We also describe how the imager can be re-configured for use with O2-sensitive materials based on Pt-porphyrin dyes using a 390 nm LED for the excitation and a bandpass 650 nm filter for emission. Overall, the PLIM imager was found to produce accurate quantitative measurements of lifetime values for the probes used and respective two-dimensional maps of the O2 concentration. It is also useful for the metabolic imaging of ex vivo tissue models and live animals.

Characterization of light induced degradation in PECVD silicon nitride passivated Cz silicon wafers using spectroscopic techniques

In this work we investigate the chemical species involved in the light induced degradation of plasma enhanced chemical vapor deposited (PECVD) hydrogenated silicon nitride (SiNx:H) passivated p-type and n-type samples under normal outdoor ambient conditions. The electrical characterization measurements along with Fourier Transform Infrared (FTIR) and photoluminescence (PL) spectroscopic techniques were utilized in this study. Significant reduction in effective minority carrier lifetime values and band to band PL intensities were noticed for both p-type and n-type samples after outdoor light soaking. The apparent defect density increased from 3.39 × 10−3 µs−1 to 1.68 × 10−2 µs−1 and 3.42 × 10−4 µs−1 to 3.46 × 10−3 µs−1, respectively for p-type and n-type samples after light soaking of 111 h corresponding to cumulative solar insolation of 95.7 kWh/m2. The changes in FTIR absorbance intensities of chemical species such as SiNyHa, SiNzHb, SiHm, SiO2i and SiOn after light soaking confirmed the role of oxygen in addition to hydrogen in both p-type and n-type samples. Spectroscopic PL analysis further validated the decrease in concentration of silicon-oxygen species and reduction in effective lifetime for n-type samples. We demonstrate that the chemical species contributing to light induced bulk and surface degradation can be identified by FTIR and PL spectroscopic techniques. This work would be beneficial for understanding, modeling and mitigating the degradation mechanisms in Cz silicon wafers passivated using PECVD dielectric films.

Interactions with HSA, anticancer and antiallergic activity of binuclear μ‐oxo bridged ruthenium acetate compounds

AbstractThe μ‐oxo bridged ruthenium acetate 1 [Ru2O(CH3COO)2(5‐CH3‐1,10‐phen)2(py)2](PF6)2 (5‐CH3‐1,10‐phen=5‐methyl‐1,10‐phenanthroline; py=pyridine) is presented. Its electronic and infrared spectra, as well as its cyclic voltammograms are all consistent with the proposed structure. Regarding biological properties, we collected data for 1 and its analog [Ru2O(CH3COO)2(1,10‐phen)2(py)2](PF6)2 (2) to infer the role of phenantroline methylation. The HSA fluorescence is quenched by 1 and the presence of variable concentrations of it did not affect the τ1/2 values for the HSA excited state lifetime (mean τ1/2 values=3.56, 3.46, and 3.32 ns at 298, 304, and 310 K respectively). Circular dichroism showed that the HSA α‐helix content decreased only 5 % upon interaction with 1, which formed a ground‐state adduct with HSA, not changing the protein structure to a significant extent. Interaction between 1 and DNA was weak; Benesi‐Hildebrand constants were in the order of 102 M−1. We probed the allergenic potential/antiallergic activity of 1, observing that 200 μM inhibited mast cell degranulation by about 80 %, while cell viability remained unaltered throughout the measurement (2 h). Therefore, 1 has antiallergic potential and is not an allergen. Regarding its anticancer activity, at all the employed concentrations, 1 was more cytotoxic than 2 against B16F10 murine melanoma cancer cells. At 25 μM, 1 reduced cell viability to less than 14 %, while 2 reduced cell viability to only 78 %.

A Prototype Wearable Device for Noninvasive Monitoring of Transcutaneous Oxygen.

Transcutaneous oxygen monitoring is a noninvasive method for measuring the partial pressure of oxygen diffusing through the skin, which strongly correlates with changes in dissolved oxygen in the arteries. Luminescent oxygen sensing is one of the techniques for assessing transcutaneous oxygen. Intensity- and lifetime-based measurements are two well-known methods used in this technique. The latter is more immune to optical path changes and reflections, making the measurements less vulnerable to motion artifacts and skin color changes. Although the lifetime-based method is promising, the acquisition of high-resolution lifetime data is crucial for accurate transcutaneous oxygen measurements from the human body when skin is not heated. We have built a compact prototype along with its custom firmware for the lifetime estimation of transcutaneous oxygen with a provision of a wearable device. Furthermore, we performed a small experiment study on three healthy human volunteers to prove the concept of measuring oxygen diffusing from the skin without heating. Lastly, the prototype successfully detected changes in lifetime values driven by the changes in transcutaneous oxygen partial pressure due to pressure-induced arterial occlusion and hypoxic gas delivery. The prototype resolved a minimum change of 1.34ns in a lifetime that corresponds to ∼0.031mmHg in response to slow changes in the oxygen pressure in the volunteer's body caused by hypoxic gas delivery. The prototype is believed to be the first in the literature to successfully conduct measurements in human subjects using the lifetime-based technique.

The influence of Eu3+ doping on the optical and structural properties of the Ge2Y2O7 crystalline phase through a soft chemical process

The present work reports on the synthesis, structural and optical properties of Ge2Y2-xEuxO7 composition powders, with x ranging from 0.0 to 0.16 (from 0.0 to 4.0 mol% Eu3+). We synthesized stable and transparent sols, homogeneous gels, and powders treated at 1100 °C by a soft chemical route, and the effect of Eu3+ concentrations was evaluated. X-ray diffraction (XRD), infrared vibrational spectroscopy (FTIR), Raman spectroscopy, diffuse reflectance spectroscopy (DRS), emission and excitation photoluminescence spectroscopy (PL, PLE), decay curves of emission intensity as a function of time and quantum yield were obtained. An annealing temperature of 1100 °C was enough to obtain a single Ge2Y2O7 crystalline phase and the decrease of Χ2 value (from 2.32 to 1.74) with the increase of Eu3+ doping in the matrix, observed with the Rietveld refinement of the XRD patterns of the samples, is due to the crystallization process. Diffuse reflectance spectra and optical bandgap of 4.7 eV for Ge2Y0.88Eu0.12O7 (3.0 mol% Eu3+) – determined by Kubelka- Munk model – showed the good optical quality of the samples, which were considered non-conducting. All doped samples possessed visible photoluminescence emission from Eu3+ ions under excitation at 394 nm, with higher emissions occurring in the red region from 5D0 → 7F2 transition, with R/O relation equal to 2.6 and purity of red color higher than 85 % for the sample with x = 0.012. Analyzing photoluminescence emission spectra, the lifetime values and Judd-Ofelt parameters, we determined that Eu3+ occupied two different sites of the Ge2Y2O7 host matrix, replacing Y3+ ions, with the quenching concentration occurring between x = 0.12 and x = 0.16. The average decay lifetime of 5D0 level from Eu3+ was around 1.66 ms, with average quantum efficiency around of 48 % and an internal quantum yield equal to 7.17 %. Moreover, we evaluated their emission luminescence properties upon 394 nm excitation to explore for the first time the possibility of using this material in thermal sensing applications.

Effect of film stress on different electrical properties of PECVD grown SiNx films and its bilayer structures: A study of Si surface passivation strategy

The prevalence of stress during thin film deposition has a substantial influence on the surface passivation of CMOS image sensors (CIS). Our present research thoroughly addresses the effect of film stress on minority carrier lifetime and interface trap density (Dit) of as-deposited and forming gas annealed (FGA, 5% H2, 400 °C for 30 min) SiNx films and their bilayer structures. In this study, plasma-enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD) techniques were utilized to synthesize SiNx and SiNx/(top) Al2O3 bilayer structures. After FGA, the minority carrier lifetime and Dit values for 50 nm-SiNx (1607 μs, 7 × 1011 cm−2eV−1), 30 nm-Al2O3 (2670 μs, 7 × 1011 cm−2eV−1), 7 nm-SiNx/30 nm-Al2O3 (1750 μs, 6 × 1011 cm−2eV−1) and 50 nm-SiNx/30 nm-Al2O3 (2300 μs, 34 × 1011 cm−2eV−1) were found. Our statistical analysis indicates that the stress in the SiNx/Al2O3 bilayer structures introduces defects in the films. This affects the carrier lifetime along with Dit values and hence degrades CIS performance. Further, we also performed a stress simulation of SiNx films which corroborated with the overall analysis. We hope that this work facilitates a better understanding of the stress effect on the surface passivation of CIS applications.

Cage Dynamics-Mediated High Ionic Transport in Li-O2 Batteries with a Hybrid Aprotic Electrolyte: LiTFSI, Sulfolane, and N,N-Dimethylacetamide

Mixed electrolytes perform better than single solvent electrolytes in aprotic lithium-O2 batteries in terms of stability and transportation. According to an experimental study, a mixed electrolyte consisting of dimethylacetamide (DMA)/sulfolane (TMS) with lithium bisfluorosulfonimide (LiTFSI) showed high ionic conductivity, oxygen solubility, remarkable stability, and better cycle life than only DMA-based or TMS-based electrolytes. In this work, we used classical molecular dynamics simulations to explore the structure and ionic dynamics of the DMA/TMS hybrid electrolytes at two compositions. We calculated radial, combined, and spatial distribution functions for the structural examination. These properties depict a minimal change in the electrolyte structure by increasing the DMA content in the electrolyte from 20 to 50% by volume. We used the diffusive regimes from mean square displacements for diffusion coefficient calculations. Ionic conductivities calculated using the Green-Kubo equation have an acceptable agreement with the experimental values, whereas the Nernst-Einstein relation is found insufficient to explain the ionic transport. The relatively lower value of the ion-cage lifetime of electrolyte components with 50% DMA shows their faster dynamics. Moreover, we present the new physical insight by focusing on ion-pair and ion-cage formation and their correlation with ionic conductivity. The atomic-level understanding through this work may assist in designing electrolytes for aprotic Li-O2 cells.

Experimental Study of the Impact of Notches Made in the Front Edge of Adherends on the Properties of Static and Fatigue Strength of Adhesive Joints

This paper presents the effect of simple structural changes consisting in making notches on the edge of adherends on the static and fatigue properties of adhesive joints. The study is based on the set of experimental static strength tests of the single lap shear adhesive joints. It has been shown that a slight increase in load capacity is possible by using adhesive-filled notches. However, this structural modification leads to an increase in the standard deviation of test results. Based on the fatigue strength tests done at the limit number of cycles equal to 2×106, it was shown that the use of notches on the front edge of adherends, which are filled with adhesive, can significantly increase the fatigue lifetime of the joint. The effect is shown in the area of low-cycle fatigue, where for fatigue stress with a maximum value of 11.5 MPa, an increase in the average value of fatigue lifetime by 481.5% was shown for joints with notches. On the basis of fractography analyses using SEM microscopy, it was shown that the positive effect of the notches is caused by the absorption of some energy by the adhesive filling the notches, due to the increased susceptibility of the adhesive in this area to elastic deformations.

Synthesis and characterization of tris(5,7-diphenyl-8-quinolinolato) aluminum(III), gallium(III), and indium(III) complexes: Effect of metal ions on the structural, photoluminescence, thermal and electrochemical properties

The 5,7-diphenyl-8-hydroxyquinoline (5,7-Phq) organic ligand was successfully synthesized via Suzuki cross-coupling reaction followed by synthesis of the novel organometallic complexes tris(5,7-diphenyl-8-quinolinolato) metal(III) [M(5,7-Phq)3; M = Al, Ga, or In]. All synthesized M(5,7-Phq)3 complexes were characterized using various analytical techniques. The molecular structure of In(5,7-Phq)3 was confirmed using single-crystal X-ray crystallography, which indicates that the three 5,7-Phq ligands are arranged in a meridional configuration around the central metal In3+ ion, and the complex is distorted from ideal octahedral geometry. There are no significant differences in the UV–visible absorption spectra of the complexes in the tetrahydrofuran (THF) solution and they are all red-shifted compared to that of the parent Mq3 (M = Al3+, Ga3+, In3+) compounds. The broad absorption band at around 417 nm is assignable to the π-π* transition. The synthesized M(5,7-Phq)3 complexes in the solution and in the solid-state show red-shifted emission compared to that of the parent unsubstituted compounds. The decrease in the solution and the solid-state emission efficiency and intensity from Al to In complexes is attributed to the heavy atom effect. Despite the electrochemical band gap energies (Egec) of the complexes determined from cyclic voltammetry being in good agreement with those reported for the unsubstituted complexes, the optical band gap energies (Egopt) determined from the Tauc plot method are smaller. The results of the fluorescence decay of the M(5,7-Phq)3 complexes both in CHCl3 solution and in solid state at 298 K show that the decays fit a bi-exponential model with two lifetimes (τ1 and τ2). The average values of fluorescence lifetimes of the complexes in CHCl3 are significantly greater than those of the complexes in the solid state.

Studying the kinetic of midodrine degradations using TLC stability approach: Application to dosage form and human plasma

A simple, rapid and selective thin layer chromatographic method has been developed for estimation of the antihypotension drug, midodrine hydrochloride, in pure form, tablet, spiked plasma and artificially degraded samples. Separation was carried out using silica gel 60-F254 as a stationary and mobile phase consisting of methanol: methylene chloride: ammonia in ratio of 8:2:0.2. The detection was carried out at wavelength of 290 nm. The retardation factor was found to be 0.7 and 0.49 for midodrine and its main degradation product desglymidodrine. The method showed linearity for midodrine over a concentration range of 50–1500 ng/spot with good correlation and determination coefficient. The method was applied successfully for analysis of commercial tablets and oral drops with good recovery and without interference of excipients. The method also was applied for studying the stability of the cited drug under different stress conditions including acidic, alkaline, hydrolytic, oxidative and photo- degradations. Furthermore, the kinetic of acidic and alkaline degradations was investigated and the rate constants were found to be 0.620 and 0.074 K h−1 while half life time (t1/2) values were 1.12 and 9.32 h, respectively.

Characterization of a bimodal multi-fibre optic clinical probe for in situ tissue diagnosis based on spectrally-and temporally-resolved autofluorescence

Introduction: Fibred-based optical spectroscopy is advantageous over imaging due to its sensitivity, practicality and precision, providing point of care diagnosis. The unique advantage is that the sampled volume is well defined by the source-detector geometry and that the functionality of multiple optical techniques can be incorporated into one probe so that more information is gained without extra bulkiness or cost, while also mitigating the limitations of each.Methods: This advantage is utilized here to address the limited accuracy in delineating brain tumors, in situ, by simultaneously characterizing tissue based on the spectral and lifetime properties of five endogenous fluorophores commonly present in brain tissue. A 5-meters multi fibre-optic probe custom-built for neurosurgery guidance with a sterilizable distal end is presented in this paper. It describes its technical features such as architecture, collection efficiency, sensitivity.Results and discussion: The developed probe have a temporal resolution of 34.6 ps and a temporal impulse response function of 29 ps. The spatial resolution was around 153 μm while the spectral resolution is 1 nm. All of these specifications are ensured under 1 second as acquisition time. The probe is validated using fluorescent dyes and tissue phantoms. Additionally, the fluorescence spectra from fresh and frozen animal tissue and from an epileptic patient are compared to that obtained from confocal fluorescence microscopy, while the lifetime values are compared to that reported in literature. Finally, the effect of pressure applied to the probe in contact with tissue is discussed.

Ce[formula omitted][formula omitted] Cr3＋ energy transfer in Y[formula omitted]Al[formula omitted]MgSiO12 garnet host and application in horticultural lighting

In this study, the photoluminescence properties of Y3Al3MgSiO12:Cr3＋ (YMASG:Cr3＋) and Y3Al3MgSiO12: 2%Ce3+, Cr3＋ (YMASG:2%Ce3+, Cr3＋) were investigated, and the energy transfer from Ce3+ to Cr3＋ were examined. All phosphor samples were prepared by the aqueous sol–gel method. The phase purity and surface morphology of the obtained sample was evaluated using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). To determine the photoluminescence (PL) properties of YMASG:Cr3＋ and YMASG:2%Ce3+, Cr3＋, emission and excitation spectra along with reflection spectra were recorded. PL decay measurements were also performed, and PL lifetime values were determined. It was found that Ce3+ → Cr3＋ energy transfer efficiency increases with increasing Cr3＋ concentration. To investigate the temperature-dependent emission of YMASG:Cr3＋ and YMASG:2%Ce3+, Cr3＋, PL emission, and PL decay measurements were conducted in a temperature range from 77 to 500 K. Temperature-dependent PL decay measurements also revealed that the Cr3＋ ions mainly cause thermal quenching of YMASG:2%Cfe3+, 1%Cr3＋ emission. To check the suitability of synthesized materials to be applied for greenhouse illumination, two pcLEDs containing YMASG:Cr3＋ and YMASG:Ce3+, Cr3＋ phosphors were constructed. PcLED prototypes applicability for efficient horticulture lighting was also investigated within this study.

Cell tracking of convective rainfall: sensitivity of climate-change signal to tracking algorithm and cell definition (Cell-TAO v1.0)

Abstract. Lagrangian analysis of convective precipitation involves identifying convective cells (“objects”) and tracking them through space and time. The Lagrangian approach helps to gain insight into the physical properties and impacts of convective cells and, in particular, how these may respond to climate change. Lagrangian analysis requires both a fixed definition of what constitutes a convective object and a reliable tracking algorithm. Whether the climate-change signals of various object properties are sensitive to the choice of tracking algorithm or to how a convective object is defined has received little attention. Here we perform ensemble pseudo-global-warming experiments at a convection-permitting resolution to test this question. Using two conceptually different tracking algorithms, Lagrangian analysis is systematically repeated with different thresholds for defining a convective object, namely minimum values for object area, intensity and lifetime. It is found that the threshold criteria for identifying a convective object can have a strong and statistically significant impact on the magnitude of the climate-change signal, for all analysed object properties. The tracking method, meanwhile, has no impact on the climate-change signal as long as the precipitation data have a sufficiently high temporal resolution: in general, the lower the minimum permitted object size is, the higher the precipitation data's temporal resolution must be. For the case considered in our study, these insights reveal that irrespective of the tracking method, projected changes in the characteristics of convective rainfall vary considerably between cells of differing intensity, area and lifetime.

Niobium incorporation into rare-earth doped aluminophosphate glasses: Structural characterization, optical properties, and luminescence

Luminescent Rare Earth (RE3+) doped phosphate glasses with molar composition (1-x)(60P2O5 – 15ZnO – 5Al2O3 – 10BaO – 10PbO)-xNb2O5 (x = 0, 10, 20 and 30 wt%) doped with 1.0, 1.2 and 0.3 wt% of Eu2O3, Yb2O3 and Er2O3, respectively, were prepared by conventional melt cooling. The glasses were characterized by optical reflectance, Raman scattering, and multinuclear (31P, 27Al, and 93Nb) solid-state NMR spectroscopy. Monotonic 31P chemical shift changes as a function of Nb2O5 content are consistent with the successive formation of Nb-O-P linkages. Aluminum is found in four-, five-, and six-coordination, with a successive decrease in average coordination number with increasing niobium content, while 93Nb NMR indicates three distinct niobium environments in these glasses. Incorporation of Nb2O5 has the expected effects on refractive index values, optical basicity, optical electronegativity, Urbach Energy, and the indirect bandgap, while RE3+ emission properties are only slightly modified. Under UV excitation, narrow emission bands are observed arising from 5D0→7FJ (J = 0, 1, 2, 3, and 4) transitions of Eu3+. At least two distinct Eu3+ lifetime values are observed, suggesting a spread of different ionic environments within the glass structure. Co-doping with Er3+/Yb3+ promotes emission in the infrared region, with a emission band maximum near 1535 nm and a width of 30.65 nm under excitation at 980 nm. Based on the results, these glasses may be potential candidates for energy conversion from infrared or UV region to the visible region and also infrared solid-state emitters.

S-nitrosylation of CaMKII cys273 suppresses CaMKII activation and translocation within cardiac myocytes.

In this study, we demonstrate that the Cys273 site on Calcium/Calmodulin-Dependent Protein Kinase II δ (CaMKII δ) is critical for nitric oxide (NO)-induced suppression of CaMKIIδ activation and mobility in adult ventricular myocytes. CaMKII is also regulated by nitrosylation in a potential positive feedback mechanism via S-Nitrosylation of Cys290 on CaMKIIδ which promotes autonomous kinase activity, versus S-Nitrosylation of Cys273 that suppresses activation by Ca-CaM. This suggests a complex interaction between NO and CaMKII in cells with fluctuating [Ca] - like cardiomyocytes. The (patho)physiological role of CaMKII nitrosylation in the cardiomyocyte, however, remains poorly understood. Here, using mutant CaMKIIδ variants of our FRET-based CaMKII activity sensor ‘Camui’ and GFP-tagged constructs of CaMKIIδ lacking the Cys273 S-nitrosylation site (CaMKIIδ-C273S), we assessed CaMKII activation and mobility after exposure to the NO donor S-nitrosoglutathione (GSNO) and Ca. We determined this by measuring Camui fluorescence lifetime values (FLIM) and assessing changes in CaMKII-GFP mobility using FRAP, in cardiomyocytes in the presence and absence of pre-treatment with GSNO. We show that in ventricular cardiomyocytes, nitrosylation of CaMKII at Cys273 prior to electrical field stimulation and activation by Ca2+ or β-adrenergic agonists suppresses CaMKIIδ activity and mobility, whereas mutation of the Cys273 to Serine prevents this effect. These findings support the suggestion that CaMKII nitrosylation at Cys273 could protect from the overactivation of CaMKIIδ in the heart, which has been implicated in numerous pathological states, including the progression from hypertrophy to heart failure, cardiac fibrosis, diabetic hyperglycemia, and upon reperfusion after ischemia.