593 research outputs found

    Concentration- and temperature- dependent luminescence quenching and optical transition of Sr2GdTaO6: Eu3+ phosphor for potential applications in white LEDs

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    A series of Eu3+ doped Sr2GdTaO6 (SGT) phosphors with double perovskite structure were synthesized via a high-temperature solid-state reaction approach. The crystal structure, morphology and luminescence properties were characterized by means of X-ray diffraction, transmission electron microscope, luminescence spectroscopy and fluorescence decay lifetimes, respectively. Under the excitation of 394 nm, intense red emission in the visible region was observed in Eu3+ doped SGT phosphors, and the critical quenching concentration of Eu3+ in SGT phosphors was derived to be 15 mol%. The chromaticity coordinates and color purity of SGT: 15 mol% Eu3+ were calculated to be (0.61, 0.36) an 93.82 %, respectively. Meanwhile, it was also confirmed that the electric quadrupole–quadrupole interaction is responsible for the luminescence concentration quenching of Eu3+. The internal quantum efficiency of SGT: Eu3+ phosphors with different Eu3+ concentrations were calculated. Furthermore, the crossover process was confirmed to be the main mechanism for luminescence thermal quenching based on the temperature-dependent emission spectra and temperature-dependent fluorescence lifetimes. In addition, the Judd-Ofelt parameters, radiative transition rates and branch ratios from the 5D0 emitting states to various lower energy states were evaluated with the aid of the Judd-Ofelt theory, respectively. All results indicate that SGT: Eu3+ samples are a promising red-emitting phosphor

    A simplified multi-model statistical approach for predicting the effects of forest management on land surface temperature in Fennoscandia

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    Forests interact with the local climate through a variety of biophysical mechanisms. Observational and modelling studies have investigated the effects of forested vs. non-forested areas, but the influence of forest management on surface temperature has received far less attention owing to the inherent challenges to adapt climate models to cope with forest dynamics. Further, climate models are complex and highly parameterized, and the time and resource intensity of their use limit applications. The availability of simple yet reliable statistical models based on high resolution maps of forest attributes representative of different development stages can link individual forest management practices to local temperature changes, and ultimately support the design of improved strategies. In this study, we investigate how forest management influences local surface temperature (LSTs) in Fennoscandia through a set of machine learning algorithms. We find that more developed forests are typically associated with higher LST than young or undeveloped forests. The mean multi-model estimates from our statistical system can accurately reproduce the observed LST. Relative to the present state of Fennoscandian forests, fully develop forests are found to induce an annual mean warming of 0.26 °C (0.03/0.69 °C as 5th/95th percentile), and an average cooling effect in the summer daytime from -0.85 to -0.23 °C (depending on the model). On the contrary, a scenario with undeveloped forests induces an annual average cooling of -0.29 °C (-0.61/-0.01 °C), but daytime warming in the summer that can be higher than 1 °C. A weak annual mean cooling of -0.01 °C is attributed to forest harvest from 2015 to 2018, with an increased daytime temperature in summer of about 0.04 °C. Overall, this approach is a flexible option to study effects of forest management on LST that can be applied at various scales and for alternative management scenarios, thereby helping to improve local management strategies with consideration of effects on local climate

    The Giant Radio Array for Neutrino Detection (GRAND) Collaboration -- Contributions to the 38th International Cosmic Ray Conference (ICRC 2023)

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    International audienceThe Giant Radio Array for Neutrino Detection (GRAND) is an envisioned observatory of ultra-high-energy particles of cosmic origin, with energies in excess of 100 PeV. GRAND uses large surface arrays of autonomous radio-detection units to look for the radio emission from extensive air showers that are triggered by the interaction of ultra-high-energy cosmic rays, gamma rays, and neutrinos in the atmosphere or underground. In particular, for ultra-high-energy neutrinos, the future final phase of GRAND aims to be sensitive enough to discover them in spite of their plausibly tiny flux. Presently, three prototype GRAND radio arrays are in operation: GRANDProto300, in China, GRAND@Auger, in Argentina, and GRAND@Nancay, in France. Their goals are to field-test the design of the radio-detection units, understand the radio background to which they are exposed, and develop tools for diagnostic, data gathering, and data analysis. This list of contributions to the 38th International Cosmic Ray Conference (ICRC 2023) presents an overview of GRAND, in its present and future incarnations, and a look at the first data collected by GRANDProto13, the first phase of GRANDProto300

    Litter decomposition and nutrient release are faster under secondary forests than under Chinese fir plantations with forest development

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    Abstract In terrestrial ecosystems, leaf litter is the main source of nutrients returning to the soil. Understanding how litter decomposition responds to stand age is critical for improving predictions of the effects of forest age structure on nutrient availability and cycling in ecosystems. However, the changes in this critical process with stand age remain poorly understood due to the complexity and diversity of litter decomposition patterns and drivers among different stand ages. In this study, we examined the effects of stand age on litter decomposition with two well-replicated age sequences of naturally occurring secondary forests and Chinese fir (Cunninghamia lanceolata) plantations in southern China. Our results showed that the litter decomposition rates in the secondary forests were significantly higher than those in the Chinese fir plantations of the same age, except for 40-year-old forests. The litter decomposition rate of the Chinese fir initially increased and then decreased with stand age, while that of secondary forests gradually decreased. The results of a structural equation model indicated that stand age, litter quality and microbial community were the primary factors driving nutrient litter loss. Overall, these findings are helpful for understanding the effects of stand age on the litter decomposition process and nutrient cycling in plantation and secondary forest ecosystems

    iTRAQ-based comparative proteomics reveal an enhancing role of PRDX6 in the freezability of Mediterranean buffalo sperm

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    Abstract Background Semen cryopreservation is a critical tool for breed improvement and preservation of biodiversity. However, instability of sperm freezability affects its application. The Mediterranean buffalo is one of the river-type buffaloes with the capacity for high milk production. Until now, there is no specific cryopreservation system for Mediterranean buffalo, which influences the promotion of excellent cultivars. To improve the semen freezing extender used in cryopreservation of Mediterranean buffalo, different protein datasets relating to freezability sperm were analyzed by iTRAQ-based proteomics. This study will be beneficial for further understanding the sperm freezability mechanism and developing new cryopreservation strategy for buffalo semen. Results 2652 quantified proteins were identified, including 248 significantly differentially expressed proteins (DEP). Gene Ontology (GO) analysis indicated that many these were mitochondrial proteins, enriched in the molecular function of phospholipase A2 activity and enzyme binding, and biological processes of regulation of protein kinase A signaling and motile cilium assembly. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis identified 17 significant pathways, including oxidative phosphorylation (OXPHOS). Furthermore, 7 DEPs were verified using parallel reaction monitoring or western blot, which confirmed the accuracy of the iTRAQ data. Peroxiredoxin 6 (PRDX6), which expressed 1.72-fold higher in good freezability ejaculate (GFE) compared to poor freezability ejaculate (PFE) sperms, was selected to explore the function in sperm freezability by adding recombinant PRDX6 protein into the semen freezing extender. The results showed that the motility, mitochondrial function and in vitro fertilization capacity of frozen-thawed sperm were significantly increased, while the oxidation level was significantly decreased when 0.1 mg/L PRDX6 was added compared with blank control. Conclusions Above results revealed the metabolic pattern of freezability of Mediterranean buffalo sperms was negatively associated with OXPHOS, and PRDX6 had protective effect on cryo-damage of frozen-thawed sperms

    Investigating the local temperature response to forest management with a regional climate model

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    Data used in the manuscript "Investigating the local temperature response to forest management with a regional climate model" which will be submitted to Journal of Geophysical Research: Atmospheres

    Topological structures of energy flow: Poynting vector skyrmions

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    Topological properties of energy flow of light are fundamentally interesting and have rich practical applications in optical manipulations. Here, skyrmion-like structures formed by Poynting vectors are unveiled in the focal region of a pair of counter-propagating cylindrical vector vortex beams in free space. A N\'eel-Bloch-N\'eel skyrmion type transformation of Poynting vectors is observed along the light propagating direction within a volume with subwavelength feature sizes. The corresponding skyrmion type can be determined by the phase singularities of the individual components of the coherently superposed electromagnetic field in the focal region. This work reveals a new family member of optical skyrmions and may introduce novel physical phenomena associated with light scattering and optical force

    Pharmacological inhibition of IRAK4 kinase activity does not prevent cachexia in mice with pancreatic cancer

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    Abstract Background Inflammation is a hallmark of cachexia; however, effective anti‐inflammatory treatments have not yet been identified. Interleukin‐1 receptor‐associated kinase 4 (IRAK4) is a key signalling node linking interleukin‐1 receptor (IL‐1R) and toll‐like receptor (TLR) activation to the production of multiple proinflammatory cytokines that are elevated in cancer cachexia. The purpose of this work is to evaluate whether pharmacological inhibition of IRAK4 kinase activity with PF‐06426779 could prevent cachexia using a model of pancreatic cancer. The effect of appetite stimulation via the ghrelin receptor agonist anamorelin was also examined as a benchmark of clinically validated mechanisms. Methods Female C57Bl/6J mice were given an intraperitoneal injection of KrasG12D; p53R172H; Pdx1‐Cre (KPC) pancreatic tumour cells. PF‐06426779 or anamorelin treatment was initiated at the onset of anorexia. Body weight and food intake were measured throughout the study. Body composition, muscle function (force), and physical activity (treadmill running endurance) were assessed at the end of the study. Results Chronic treatment with PF‐06426779, at doses covering in vitro IC50 and IC90 at Cmin, did not increase body weight, food intake, and muscle function in the KPC tumour model. In contrast, anamorelin (vs. vehicle) increased food intake (P < 0.01), hindlimb skeletal muscle mass (P < 0.01), and muscle strength (P < 0.05); however, treadmill running endurance was not increased. Conclusions These data suggest that inhibition of IRAK4 kinase activity is not sufficient to treat cachexia, at least in pancreatic cancer, and exploration of alternative anti‐inflammatory strategies that increase appetite is required

    Elliptical Supercritical Lens for Shaping Sub-Diffractive Transverse Optical Needle

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    Supercritical lens can create a sub-diffraction-limited focal spot in the far field, providing a promising route for the realization of label-free super-resolution imaging through the point scanning mechanism. However, all of the reported supercritical lenses have circular shape configurations, and produce isotropic sub-diffraction-limited focal spots in the focal plane. Here, we propose and experientially demonstrate a sub-diffraction transverse optical needle by using an elliptical supercritical lens. Through breaking the circular symmetry and introducing ellipticity to the lens, a uniform sub-diffractive transverse optical needle with lateral length and width of 6λ/NA and 0.45λ/NA, respectively, was successfully created in the focal plane. Further, elliptical sector-shape cutting with an optimized apex angle of 60 degrees can lead to suppressed subsidiary focusing for improved uniformity and condensed field intensity of the transverse optical needle. The demonstration of sub-diffractive transverse optical needle with a high aspect ratio (length to width ratio) of 13:1 may find potential applications in line-scanning microscopy for video-rate label-free super-resolution imaging, and also enable advances in the fields from laser manufacturing to optical manipulation

    Table_1_Comparison of cumulative live birth rates between progestin-primed ovarian stimulation protocol and gonadotropin-releasing hormone antagonist protocol in different populations.docx

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    ObjectiveTo compare cumulative live birth rate (LBR) between progestin-primed ovarian stimulation (PPOS) and GnRH antagonist protocols of preimplantation genetic testing (PGT) cycles in different populations.MethodsThis was a retrospective cohort study. A total of 865 patients were enrolled and separate analyses were performed for three populations: 498 patients with predicted normal ovarian response (NOR), 285 patients with PCOS, and 82 patients with predicted poor ovarian response (POR). The primary outcome was cumulative LBR for one oocyte retrieval cycle. The results of response to ovarian stimulation were also investigated, including numbers of oocytes retrieved, MII oocytes, 2PN, blastocysts, good-quality blastocysts, and usable blastocysts after biopsy, as well as rates of oocyte yield, blastocyst formation, good-quality blastocysts, and moderate or severe OHSS. Univariable and multivariable logistic regression analyses were used to identify potential confounders that may be independently associated with cumulative live birth.ResultsIn NOR, the cumulative LBR of PPOS protocol was significantly lower than that of GnRH antagonists (28.4% vs. 40.7%; P=0.004). In multivariable analysis, the PPOS protocol was negatively associated with cumulative LBR (adjusted OR=0.556; 95% CI, 0.377-0.822) compared to GnRH antagonists after adjusting for potential confounders. The number and ratio of good-quality blastocysts were significantly reduced in PPOS protocol compared to GnRH antagonists (2.82 ± 2.83 vs. 3.20 ± 2.79; P=0.032 and 63.9% vs. 68.5%; P=0.021), while numbers of oocytes, MII oocytes and 2PN did not show any significant difference between GnRH antagonist and PPOS protocols. PCOS patients had similar outcomes as NOR. The cumulative LBR of PPOS group appeared to be lower than that of GnRH antagonists (37.4% vs. 46.1%; P=0.151), but not significantly. Meanwhile, the proportion of good-quality blastocysts in PPOS protocol was also lower compared to GnRH antagonists (63.5% vs. 68.9%; P=0.014). In patients with POR, the cumulative LBR of PPOS protocol was comparable to that of GnRH antagonists (19.2% vs. 16.7%; P=0.772). There was no statistical difference in the number and rate of good-quality blastocysts between the two protocols in POR, while the proportion of good-quality blastocysts appeared to be higher in PPOS group compared to GnRH antagonists (66.7% vs. 56.3%; P=0.182). In addition, the number of usable blastocysts after biopsy was comparable between the two protocols in three populations.ConclusionThe cumulative LBR of PPOS protocol in PGT cycles is lower than that of GnRH antagonists in NOR. In patients with PCOS, the cumulative LBR of PPOS protocol appears to be lower than that of GnRH antagonists, albeit lacking statistical difference, whereas in patients with diminished ovarian reserve, the two protocols were comparable. Our findings suggest the need for caution when choosing PPOS protocol to achieve live births, especially for normal and high ovarian responders.</p