ABSTRACT We report on the extensive multi-wavelength observations of the blazar Markarian 421 (Mrk 421) covering radio to γ-rays, during the 4.5 year period of ARGO-YBJ and Fermi common operation ...time, from 2008 August to 2013 February. These long-term observations, extending over an energy range of 18 orders of magnitude, provide a unique chance to study the variable emission of Mrk 421. In particular, due to the ARGO-YBJ and Fermi data, the entire energy range from 100 MeV to 10 TeV is covered without any gap. In the observation period, Mrk 421 showed both low- and high-activity states at all wavebands. The correlations among flux variations in different wavebands were analyzed. The X-ray flux is clearly correlated with the TeV γ-ray flux, while the GeV γ-rays only show a partial correlation with the TeV γ-rays. Radio and UV fluxes seem to be weakly or not correlated with the X-ray and γ-ray fluxes. Seven large flares, including five X-ray flares and two GeV γ-ray flares with variable durations (3-58 days), and one X-ray outburst phase were identified and used to investigate the variation of the spectral energy distribution with respect to a relative quiescent phase. During the outburst phase and the seven flaring episodes, the peak energy in X-rays is observed to increase from sub-keV to a few keV. The TeV γ-ray flux increases up to 0.9-7.2 times the flux of the Crab Nebula. The behavior of GeV γ-rays is found to vary depending on the flare, a feature that leads us to classify flares into three groups according to the GeV flux variation. Finally, the one-zone synchrotron self-Compton model was adopted to describe the emission spectra. Two out of three groups can be satisfactorily described using injected electrons with a power-law spectral index around 2.2, as expected from relativistic diffuse shock acceleration, whereas the remaining group requires a harder injected spectrum. The underlying physical mechanisms responsible for different groups may be related to the acceleration process or to the environment properties.
Data from clinical trials of human papillomavirus (HPV) vaccines showed that women naïve (negative for both type-specific antibodies and DNA) to vaccine types would derive benefit from vaccination; ...therefore, an understanding of the proportion of naïve women in different age groups is important for developing HPV vaccination strategies.
From November 2012 to April 2013, a total of 7372 healthy women aged 18–45 years were recruited in five provinces in China. Cervical specimens and serum samples were collected for each woman at entry. Cervical specimens were first tested by the HPV DNA enzyme immunoassay method; if positive, the specimens were then tested by reverse hybridization line probe assay and HPV-16 and HPV-18 specific polymerase chain reactions. Neutralizing antibodies against HPV-16 or HPV-18 were tested with a pseudovirion-based neutralization assay.
The overall prevalence of high-risk HPV DNA was 14.8% (1088/7367, 95% CI 14.0–15.6), and the seroprevalence of neutralizing antibodies against HPV-16 and HPV-18 was 12.6% (925/7367) and 4.9% (364/7367), respectively. In younger women (18–26 years) and middle-aged women (27–45 years), 83.8% (3116/3719) and 81.4% (2968/3648) were naïve to both HPV-16 and HPV-18 (both neutralizing antibodies and DNA were negative), respectively. In addition, 98.5% (3664/3719) and 98.0% (3575/3648) of the younger or middle-aged women were naïve to at least one HPV type (HPV-16 or HPV-18).
This study revealed that the majority of Chinese women aged 18–26 years and 27–45 years were naïve to both HPV-16 and HPV-18 and would thus derive full benefit from bivalent HPV vaccination.
The evolutions of MHD instability behaviors and enhancement of both electrostatic and electromagnetic turbulence towards the plasma disruption have been clearly observed in the HL-2A plasmas. Two ...types of plasma disruptive discharges have been investigated for similar equilibrium parameters: one with a distinct stage of a small central temperature collapse (Formula: see text 5-10%) around 1 millisecond before the thermal quench (TQ), while the other without. For both types, the TQ phase is preceded by a rotating 2/1 tearing mode, and it is the development of the cold bubble from the inner region of the 2/1 island O-point along with its inward convection that causes the massive energy loss. In addition, the micro-scale turbulence, including magnetic fluctuations and density fluctuations, increases before the small collapse, and more significantly towards the TQ. Also, temperature fluctuations measured by electron cyclotron emission imaging enhances dramatically at the reconnection site and expand into the island when approaching the small collapse and TQ, and the expansion is more significant close to the TQ. The observed turbulence enhancement near the X-point cannot be fully interpreted by the linear stability analysis by GENE. Evidences suggest that nonlinear effects, such as the reduction of local Formula: see text shear and turbulence spreading, may play an important role in governing turbulence enhancement and expansion. These results imply that the turbulence and its interaction with the island facilitate the stochasticity of the magnetic flux and formation of the cold bubble, and hence, the plasma disruption.
Critical flow velocity (CFV) is one of the valid parameters to evaluate the erosion-corrosion performance of passive materials. The comparison of CFV for common passive materials is significant for ...the engineering applications. This study focuses on the comparison of CFV for different types of stainless steel (SS), including the pearlitic 2Cr13 SS, austenitic 304 SS, 316 SS, 254 SMO SS, and two duplex stainless steels (DSS) (2205 DSS and 2507 DSS) in 3.5 wt% NaCl solution containing 2 wt% silica sand particles using the impingement jet apparatus. Different methods (potentiostatic polarization tests, mass loss measurements and surface roughness measurements) were used to determine the CFV and the values of CFV derived from different methods showed a good consistency. The 254 SMO SS exhibited the highest CFV, followed by 2507 DSS, 2205 DSS and 316 SS, and 304 SS and 2Cr13 SS. Compared with the mass loss method which is normally time-consuming, comprehensive evaluation based on the critical flow velocity and current density at flow velocity higher than the critical value by using potentiostatic polarization tests is more effective and efficient for the material selection for erosion-corrosion.
•The critical flow velocity (CFV) of six stainless steels is compared.•The CFV determined by different testing methods is consistent.•CFV is a valid parameter to evaluate erosion-corrosion behavior of passive materials.
Critical flow velocity (CFV) is an effective parameter to evaluate the erosion-corrosion property of passive material. The CFV accumulation for different passive materials contributes to the material ...selection of hydraulic equipment applied in multiphase flow environments. In this paper, the CFV behaviors of Inconel 600, Inconel 625 and Incoloy 825 under impingement by a saline-sand solution have been investigated by potentiostatic polarization methods and mass loss tests. In addition, the repassivation behaviors of three Ni-based alloys were studied by a self-made indentation apparatus to clarify the CFV mechanism for erosion-corrosion. The results show that the CFV values are 13 m/s for Inconel 600, 14 m/s for Inconel 625 and 14 m/s for Incoloy 825, respectively. The higher CFV values for Inconel 625 and Incoloy 825 are mainly based on their higher repassivation rates compared with Inconel 600. The addition of Cr and Mo elements for Ni-based alloy can remarkably improve the repassivation rate, and then increase the CFV value.
•The critical flow velocity (CFV) of three Ni-based alloys was compared.•The relationship between CFV behavior and repassivation rate was discussed.•The effect of alloying elements on repassivation rate and CFV behavior was studied.
Summary
In this study, we found out a previously undefined function of icariin which restored the dynamic balance between osteogenic and adipogenic differentiation of mesenchymal stem cells (MSCs) in ...patients with osteonecrosis of femoral head (ONFH) via ABCB1-promoter demethylation. These findings provided important information regarding potential implication of icariin targeting epigenetic changes for the treatment of steroid -associated ONFH.
Introduction
Here, we investigated whether icariin can also exert a beneficial role in the reactivation of MSCs in the patients with steroid-associated ONFH via ABCB1-promoter demethylation.
Methods
Bone marrow was collected from the proximal femur in patients with steroid-associated ONFH (
n
= 20) and patients with new femoral neck fractures (
n
= 22), and then MSCs were isolated. We investigated cell viability, intracellular reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP), P-glycoprotein (P-gp) activity, the transcript levels of ABCB1 and oxidative stress-related genes, methylation extent at CpG islands of ABCB1 promoter, and osteogenic and adipogenic differentiation ability of MSCs from the femoral neck fractures group and from the steroid-associated ONFH group treated with or without icariin.
Results
We observed that MSCs from the steroid-associated ONFH group showed reduced proliferation ability, elevated ROS level, depressed MMP, weakened osteogenesis, and enhanced adipogenesis while low P-gp activity, transcription level of ABCB1, and oxidative stress-related genes as well as aberrant CpG islands hypermethylation of ABCB1 were also noted in steroid-associated ONFH group. Treatment with icariin obviously induced de novo P-gp expression, decreased oxidative stress, and promoted osteogenesis.
Conclusion
Icariin may be a potential drug targeting epigenetic changes for the treatment of steroid-associated ONFH.
•A new and effective Pb-Bi bond-order-potential (BOP) was constructed.•BOP model could accurately describe various properties of binary Pb-Bi system.•Formation, diffusion, viscosity of lead-bismuth ...eutectic melt was successfully predicted.
Lead-bismuth eutectic (LBE) alloys are currently considered one of the most promising liquid metal coolants for fast reactors, and especially accelerator-driven systems (ADS). An analytical bond-order potential (BOP) of Pb-Bi has been constructed to account for the electronic interactions and angular contribution of Pb-Bi system. The newly developed BOP has been validated to show a better performance than the Pb-Bi potentials already published in the literature. Molecular dynamics simulations based on current BOP has been adopted to investigate various properties of Pb-Bi binary system. It accurately predict the heats of formation, density, and thermal expansion coefficient of liquid LBE at 700 K. The diffusion coefficient and viscosity of liquid Pb44.5Bi55.5 are calculated, which are in good agreement with experimental observations in the literature. These findings provide a foundation for future design of Pb-Bi eutectic alloys for use in ADS and heavy-metal-cooled fast nuclear reactors.
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The famous lacquer wares excavated from the Jiuliandun Tombs of the middle and late Warring States period (476–221 BC) were analyzed using scanning electron microscopy/energy as well as dispersive ...X‐ray spectrometry (SEM/EDS), Raman spectroscopy (RS), optical microscopy (OM), and X‐ray diffraction (XRD). The results showed a multilayer structure in the lacquer film, including a Qihui layer (a layer made of lacquer and various plasters), undercoat layer (or finishing coat) and colored paint layer mixed with various inorganic particles, such as quartz (SiO2) and hydroxyapatite Ca5(PO4)3(OH), as fillers in the Qihui layers or orpiment (As2S3) and cinnabar (HgS), which were used as a yellow or red pigment, respectively. With the help of elemental mapping images, a double‐layer structure of the lacquer plaster was observed, corresponding to a mixture of lacquer liquid and bone ash Ca5(PO4)3(OH), with large‐diameter particles in the ground lacquer layer near the wooden body and small quartz (SiO2) particles in upper lacquer layer. Specifically, quartz particles detected in the undercoat layer as fillers could be beneficial for improving the moshardness value, cost reduction and abrasive resistance of the lacquer film. In fact, the mixed method that used urushi and inorganic particles to form lacquer plaster was an important technological innovation and deeply influenced lacquering technologies worldwide. The results of this study will not only contribute to understanding the importance of lacquer skills in the Chinese Warring States but also provide information for cultural relic conservation as well as modern lacquer manufacturing for their protection and duplication.
A double‐layer structure of lacquer plaster observed by elemental mapping
Large hydroxyapatite particles were found in ground lacquer and small quartz particles were found in the upper lacquer layer.
Quartz particles were used in the undercoat layer as fillers to improve the quality of the lacquer film.
Plaster made of urushi and inorganic particles was an important ancient technological innovation.
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