Cross-Correlation Detection of Point Sources in WMAP First Year Data

We apply a Cross-correlation (CC) method developed previously for detecting gamma-ray point sources to the WMAP first year data by using the Point-Spread Function of WMAP and obtain a full sky CC coefficient map. Analyzing this map, we find that the CC method is a powerful tool to examine the WMAP foreground residuals which can be further cleaned accordingly. Evident foreground signals are found in WMAP foreground cleaned maps and Tegmark cleaned map. In this process 101 point-sources are detected, and 26 of them are new sources besides the originally listed WMAP 208 sources. We estimate the flux of these new sources and verify them by another method. As a result, a revised mask file based on the WMAP first year data is produced by including these new sources.Comment: 14 pages, 10 figures; accepted for publication by ChJA

Overcoming losses in superlenses with synthetic waves of complex frequency

Superlenses made of plasmonic materials and metamaterials have been exploited to image features of sub-diffractional scale. However, their intrinsic losses impose a serious restriction on the imaging resolution, which is a long-standing problem that has hindered wide-spread applications of superlenses. Optical waves of complex frequency exhibiting a temporally attenuating behavior have been proposed to offset the intrinsic losses in superlenses via virtual gain, but the experimental realization has been missing due to the challenge involved in preparing the illumination with temporal decay. Here, by employing multi-frequency measurement, we successfully implement a synthetic optical wave of complex frequency to experimentally observe deep-subwavelength superimaging patterns enabled by the virtual gain. Our work represents a practical approach to overcoming the intrinsic losses of plasmonic systems for imaging and sensing applications.Comment: 17 pages, 3 figure

Sesamin Protects the Femoral Head From Osteonecrosis by Inhibiting ROS-Induced Osteoblast Apoptosis in Rat Model

Glucocorticoids intake has become the most common pathogenic factor for osteonecrosis of the femoral head (ONFH). Annually, tens of millions of patients suffer from pain related to ONFH. Researchers have proposed several underlying mechanisms of ONFH, including osteocyte apoptosis, cell differentiation disorder, and angiogenesis hindrance. Sesamin, isolated from Sesamum indicum seeds, was reported could affect osteocyte inflammation and differentiation in osteoarthritis and osteoporosis. We investigated the underlying influence of sesamin on ONFH rat model. Fifteen male Sprague-Dawley rats were randomly divided into three groups. The ONFH model group only received the methylprednisolone (MPS) and lipopolysaccharide (LPS) injection to promote the development of ONFH. The sesamin treatment group was injected with sesamin, MPS, and LPS. The control group was untreated. Rats from above groups were sacrificed 4 weeks later. The effect of sesamin on ONFH rats was validated by H&E staining. TUNEL staining showed that femoral head necrosis was attenuated by sesamin. Furthermore, the phosphorylation of Akt was increased and the downstream cellular apoptosis signal pathway was inhibited. Intracellular ROS level was decreased after sesamin treatment. In conclusion, our findings suggest that sesamin protects the femoral head from osteonecrosis by inhibiting ROS-induced osteoblast apoptosis

Evolution and coupling of “seepage field and chemical field” under regional grouting disturbance

In Huaibei coalfield, the technology of ground directional drilling and high-pressure grouting is widely used to control the karst water disaster of coal measures floor. After grouting, the filling and drainage path of the seepage field changes, and the grouting high pressure and the slurry water will change the distribution characteristics of the groundwater seepage field and chemical field of the injected target aquifer in a certain period of time. Taking Taoyuan Coal Mine in Huaibei Coalfield as the research object, the evolution model of seepage field and chemical field (referred to as “double field”) of the target layer under regional grouting disturbance is built by using the software of Feflow, the coupling mechanism of “double field” is discussed, and the Cl− which is less affected by the environment is selected as the simulation factor, and the analysis of the factors affecting solute transport under the “double field” coupling effect is carried out. On this basis, the mathematical model of solute diffusion under regional grouting disturbance is constructed. The results show that in the seepage field model after identification and verification, 71.9% of the points where the error between the simulated water level and the measured water level is less than 3m, and the simulation effect is good; Among the identified and verified chemical field models, the simulation effect of solute transport in mining area II4 is good, and the simulation value in mining area II1 is about 14.4 mg/L lower, with an error of about 6.6% of the actual value, less than 10%. The overall simulation effect is good. The Cl− in mining area II4 and II2 with relatively high permeability coefficient is easy to migrate and diffuse, while the rock in mining area II1 with low permeability coefficient is dense and has poor permeability. During the 50 years of model operation, it basically exists in the state of “stagnant water”. Based on the evolution characteristics of local seepage field in II4 mining area under grouting disturbance, it is considered that solute transport is mainly controlled by permeability coefficient, dispersion, hydraulic gradient, seepage velocity, grouting time, slurry specific gravity and other parameters. It is found that the concentration of Cl− reaches a peak within 18−22 years after the completion of grouting, and then begins to decrease, and reaching the equilibrium state before regional grouting approximately 40 years later. Based on the data obtained from multiple parameter setting operations, a mathematical model of solute diffusion under the “double field” coupling is established. The data with error rate less than 10% accounts for 81.4%, which indicates that the established mathematical model of solute diffusion is basically reliable. This study can provide scientific basis for the study of the water environment evolution of the injected target aquifer under the regional grouting disturbance and the prediction and early warning of coal mine water disasters, and has important theoretical and practical significance

High sulfur loading and shuttle inhibition of advanced sulfur cathode enabled by graphene network skin and N, P, F-doped mesoporous carbon interfaces for ultra-stable lithium sulfur battery

Achieving high loading of active sulfur yet rational regulating the shuttle effect of lithium polysulfide (LiPS) is of great significance in pursuit of high-performance lithium-sulfur (Li-S) battery. Herein, we develop a free-standing graphene-nitrogen (N), phosphorus (P) and fluorine (F) co-doped mesoporous carbon-sulfur (G-NPFMC-S) film, which was used as a binder-free cathode in Li-S battery. The developed mesoporous carbon (MC) achieved a high specific surface area of 921 m2·g–1 with a uniform pore size distribution of 15 nm. The inserted graphene network inside G-NPFMC-S cathode can effectively improve its electrical conductivity and simultaneously restrict the shuttle of LiPS. A high sulfur loading of 86% was achieved due to the excellent porous structures of graphene-NPFMC (G-NPFMC) composite. When implemented as a freestanding cathode in Li-S battery, this G-NPFMC-S achieved a high specific capacity (1,356 mAh·g–1), favorable rate capability, and long-term cycling stability up to 500 cycles with a minimum capacity fading rate of 0.025% per cycle, outperforming the corresponding performances of NPFMC-sulfur (NPFMC-S) and MC-sulfur (MC-S). These promising results can be ascribed to the featured structures that formed inside G-NPFMC-S film, as that highly porous NPFMC can provide sufficient storage space for the loading of sulfur, while, the N, P, F-doped carbonic interface and the inserted graphene network help hinder the shuttle of LiPS via chemical adsorption and physical barrier effect. This proposed unique structure can provide a bright prospect in that high mass loading of active sulfur and restriction the shuttle of LiPS can be simultaneously achieved for Li-S battery