Enhanced nonradiative relaxation and photoluminescence quenching in random, doped nanocrystalline powders

Nonradiative relaxation and photoluminescence quenching in nanocrystalline powders doped with rare-earth elements are of interest in optical bistability, random laser, and other optoelectronic applications. Here, the luminescence quenching of a one-dimensional random medium made of multilayer nanoparticles (Y2O3)(Y2O3) doped with rare-earth elements (Yb3+)(Yb3+) is analyzed by considering the transport, transition, and interaction of the fundamental energy carriers. The nonradiative decay and luminescence quenching in random media are enhanced compared to single crystals, due to multiple scattering, enhanced absorption, and low thermal conductivity. The coherent wave treatment is used to calculate the photon absorption, allowing for field enhancement and photon localization. The luminescent and thermal emission is considered as incoherent. The size-dependent absorption coefficient and penetration depth are observed. The nonradiative decay is identified as a multiphonon relaxation process, and is found to be enhanced compared to bulk materials. The luminescence quenching and nonlinear thermal emission, occurring with increasing irradiation intensity, are predicted.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87544/2/104331_1.pd

Treatment effect of Bushen Huayu extract on postmenopausal osteoporosis in vivo

Bushen Huayu extract (BSHY), a traditional Chinese medicine, has been demonstrated to treat postmenopausal osteoporosis, however, the underlying mechanism remains to be fully elucidated. The aim of the present study was to investigate the therapeutic effect of BSHY and the mechanisms underlying this effect in an in vivo postmenopausal osteoporosis animal model. A total of 1 g BSHY containing 7.12 μg icariin was prepared. Low-dose BSHY (BSHY-L; 11.1 g/kg), medium-dose BSHY (BSHY-M; 22.2 g/kg) and high-dose BSHY (BSHY-H; 44.4 g/kg) was administered to oophorectomized rats using intragastric infusion. Estradiol (E2), interleukin-6 (IL-6) and serum alkaline phosphatase (ALP) levels, as well as bone density, were determined. It was found that the levels of serum ALP in the BSHY-L, BSHY-M and BSHY-H groups (197.75±41.74, 166.63±44.83 and 165.63±44.90 IU/l, respectively) were significantly decreased compared with the model group (299.13±45.79 IU/l; P<0.05), whilst the levels of E2 (16.89±1.71, 17.95±1.40 and 18.34±1.43 pg/ml, respectively) increased compared with the model group (14.54±1.61; P<0.05). In addition, the levels of IL-6 decreased in the BSHY-L, BSHY-M and BSHY-H groups (91.85±14.81, 82.99±15.65 and 80.54±14.61 pg/ml, respectively) compared with the model group (105.93±16.50 pg/ml; P<0.05). Furthermore, it was demonstrated that BSHY increased the bone density in the BSHY-L, BSHY-M and BSHY-H groups (0.20±0.014, 0.22±0.016 and 0.22±0.017 g/cm2, respectively) compared with the model group (0.19±0.011 g/cm2; P<0.05). BSHY was also found to increase the number of osteoblasts in the BSHY-L, BSHY-M and BSHY-H groups (25.38±2.17, 29.25±2.12 and 30.00±2.39, respectively), compared with in the model group (14.75±2.38; P<0.05), and decrease the number of osteoclasts in the BSHY-L, BSHY-M and BSHY-H groups (4.00±1.85, 4.25±1.39 and 5.75±1.49, respectively) compared with 9.50±1.60 observed in the model group (P<0.05). These results suggest that BSHY is a potential therapeutic drug for the treatment of osteoporosis in vivo. Furthermore, these results suggest that the mechanism by which BSHY decreases the serum levels of IL-6 may be by regulating E2.published_or_final_versio

Review of data-driven methods used to control the normalization of the top quark background contribution in the H --> WW(*) --> {\ellν\ellν} analyses at the LHC

A few data-driven methods used in deriving the normalization of the dominant top quark background contribution in the $H → WW(*) → {\ellν\ellν}$ analyses by the ATLAS and CMS experiments at the LHC are reviewed and compared. Additional information, justi fication or modi fication to some of the methods is provided. These methods have also been or can be applied to other analyses such as cross section measurements of the Standard Model WW process and searches for new physics in channels with similar final states

Petroleum generation timing and source in the Northern Longmen Shan Thrust Belt, Southwest China: Implications for multiple oil generation episodes and sources

The temporal evolution of hydrocarbons (∼500 million bbl) and its relationship to the orogenic events of the Longmen Shan thrust belt have been extensively debated. The hydrocarbons occur as solid bitumen, as dykes and/or coatings within/along faults/fractures, and as present-day oil seeps. Here, utilizing organic geochemistry, we demonstrate that all of the bitumen exhibit similar organo-geochemical characteristics, and were sourced from the upper Neoproterozoic–lower Cambrian Doushantuo and Qiongzhusi Formations. In contrast, the organic geochemistry of the present-day oil seeps are distinct from that of the bitumen, and suggest that the source is the Permian Dalong Formation. Bitumen Re-Os data indicate that the upper Neoproterozoic–lower Cambrian Doushantuo and Qiongzhusi Formations underwent two temporally distinct oil-generation events; initial oil generation occurred during the Late Cambrian/Early Ordovician prior to the Caledonian orogeny, and secondly during the Jurassic (∼165 Ma) coinciding with the Indosinian-Yanshan orogenies. In contrast, the Re-Os data of the present-day oil seeps are too similar to yield a meaningful age, although the source is considered to have undergone hydrocarbon maturation between the Triassic and Jurassic. The temporal hydrocarbon evolution in the Longmen Shan thrust belt also provides an understanding of the hydrocarbon evolution and future exploration of the adjacent petroliferous Sichuan Basin

The patterns and implications of diurnal variations in the d-excess of plant water, shallow soil water and air moisture

Deuterium excess (d-excess) of air moisture is traditionally considered a conservative tracer of oceanic evaporation conditions. Recent studies challenge this view and emphasize the importance of vegetation activity in controlling the dynamics of air moisture d-excess. However, direct field observations supporting the role of vegetation in d-excess variations are not well documented. In this study, we quantified the d-excess of air moisture, shallow soil water (5 and 10 cm) and plant water (leaf, root and xylem) of multiple dominant species at hourly intervals during three extensive field campaigns at two climatically different locations within the Heihe River basin, northwestern China. The ecosystems at the two locations range from forest to desert. The results showed that with the increase in temperature (T) and the decrease in relative humidity (RH), the δD–δ18O regression lines of leaf water, xylem water and shallow soil water deviated gradually from their corresponding local meteoric water line. There were significant differences in d-excess values between different water pools at all the study sites. The most positive d-excess values were found in air moisture (9.3‰) and the most negative d-excess values were found in leaf water (−85.6‰). The d-excess values of air moisture (dmoisture) and leaf water (dleaf) during the sunny days, and shallow soil water (dsoil) during the first sunny day after a rain event, showed strong diurnal patterns. There were significantly positive relationships between dleaf and RH and negative relationships between dmoisture and RH. The correlations of dleaf and dmoisture with T were opposite to their relationships with RH. In addition, we found opposite diurnal variations for dleaf and dmoisture during the sunny days, and for dsoil and dmoisture during the first sunny day after the rain event. The steady-state Craig–Gordon model captured the diurnal variations in dleaf, with small discrepancies in the magnitude. Overall, this study provides a comprehensive and high-resolution data set of d-excess of air moisture, leaf, root, xylem and soil water. Our results provide direct evidence that dmoisture of the surface air at continental locations can be significantly altered by local processes, especially plant transpiration during sunny days. The influence of shallow soil water on dmoisture is generally much smaller compared with that of plant transpiration, but the influence could be large on a sunny day right after rainfall events

Large exchange bias after zero-field cooling from an unmagnetized state

Exchange bias (EB) is usually observed in systems with interface between different magnetic phases after field cooling. Here we report an unusual phenomenon in which a large EB can be observed in Ni-Mn-In bulk alloys after zero-field cooling from an unmagnetized state. We propose this is related to the newly formed interface between different magnetic phases during the initial magnetization process. The magnetic unidirectional anisotropy, which is the origin of EB effect, can be created isothermally below the blocking temperature.Comment: including supplementary information, Accepted by Physical Review Letter

A Learning-Based Steganalytic Method against LSB Matching Steganography

This paper considers the detection of spatial domain least significant bit (LSB) matching steganography in gray images. Natural images hold some inherent properties, such as histogram, dependence between neighboring pixels, and dependence among pixels that are not adjacent to each other. These properties are likely to be disturbed by LSB matching. Firstly, histogram will become smoother after LSB matching. Secondly, the two kinds of dependence will be weakened by the message embedding. Accordingly, three features, which are respectively based on image histogram, neighborhood degree histogram and run-length histogram, are extracted at first. Then, support vector machine is utilized to learn and discriminate the difference of features between cover and stego images. Experimental results prove that the proposed method possesses reliable detection ability and outperforms the two previous state-of-the-art methods. Further more, the conclusions are drawn by analyzing the individual performance of three features and their fused feature