XMM-Newton observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.326

A brief Chandra observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.326 showed it to be a relatively bright, soft X-ray source with a count rate of about 1 count ks−1. In this article, we present results for the quasar from a 65-ks XMM–Newton observation, which constrains its spectral shape well. The quasar is clearly detected with a total of ~460 net counts in the 0.2–10 keV band. The spectrum is characterized by a simple power-law model with a photon index of = 2.30+0.10 −0.10 and the intrinsic 2–10 keV luminosity is 3.14 × 1045 erg s−1. The 1σ upper limit to any intrinsic absorption column density is NH = 6.07 × 1022 cm−2. No significant iron emission lines were detected. We derive an X-rayto-optical flux ratio αox of −1.74 ± 0.01, consistent with the values found in other quasars of comparable ultraviolet luminosity. We did not detect significant flux variations either in the XMM–Newton exposure or between XMM–Newton and Chandra observations, which are separated by ∼8 months. The X-ray observation enables the bolometric luminosity to be calculated after modelling the spectral energy distribution: the accretion rate is found to be sub-Eddington

Formation Mechanism and Cohesive Energy Analysis of Metal-coated Graphene Nanocomposites Using In-situ Co-reduction Method

Abstract: Nanocomposite powders based on metal-coated graphene were synthesized using an in-situ co-reduction method in order to improve wettability and interfacial bonding between graphene and metal. Graphene oxide (GO) of 2~3 atomic layers was synthesized using the Hummer’s method with graphite as a raw material, and then dispersed into a dispersing agent solution mixed with N-Methyl pyrrolidone and deionized water to form a homogeneous GO suspension, which was finally added into electroless plating solutions for the reduction process. Copper-coated graphene (Cu@graphene) and nickel-coated graphene (Ni@graphene) were synthesized using this one-step and co-reduction method by mixing salt solutions containing metal ions and GOs into the plating solution. The copper ions or nickel ions were adsorbed and bonded onto the edges and surfaces of graphene, which was reduced from the GOs using a strong reducing agent of ascorbic acid or sodium borohydride. Crystalline copper particles with an average size of about 200 nm were formed on the surface of graphene, whereas amorphous or nanocrystalline nickel particles with an average size of 55 nm were formed on the surface of graphene. Distribution of these metal particles on the graphene is homogeneous and highly dispersed, which can effectively improve the sinterability of composite powders. Cohesive energy distribution between graphene and metal interface was analyzed using first-principle calculation method. Formation mechanism of metal coated graphene was identified to be that both the GO and metal ions were simultaneously reduced in the reducing agents, and thus a strong chemical bonding of graphene/metal was formed between the metal particles and graphene

A simple method to prepare highly active and dispersed Ni/MCM-41 catalysts by co-impregnation

A simple method for preparing highly active and dispersed supported metal catalysts was developed by co-impregnation. Compared with conventional wetness impregnation, addition of moderate ethylene glycol into the metal nitrate aqueous solution could enhance interaction with MCM-41 surface, resulting in formation of very small NiO particle size (3.5 nm) and high dispersion of the active phase. The Ni/MCM-41 catalysts using co-impregnation exhibited excellent catalytic performance for low temperature hydrogenation of naphthalene with 100% conversion at 55 degrees C, which could rival the activity of commercial Raney Ni catalyst. The obtained catalysts were characterized by XRD, TEM, TG-DSC, FT-IR, BET and TPR. (C) 2013 Published by Elsevier B.V

Effect of Calcination Temperature on Catalytic Activity and Textual Property of Cu/HMOR Catalysts in Dimethyl Ether Carbonylation Reaction

The effect of calcination temperature on the catalytic activity for the dimethyl ether (DME) carbonylation into methyl acetate (MA) was investigated over mordenite supported copper (Cu/HMOR) prepared by ionexchange process. The results showed that the catalytic activity was obviously affected by the calcination temperature. The maximal DME conversion of 97.2% and the MA selectivity of 97.9% were obtained over the Cu/HMOR calcined at 430 ±C under conditions of 210 ±C, 1.5 MPa, and GSHV of 4883 h~(-1). The obtained Cu/HMOR catalysts were characterized by powder X-ray diffraction, N_2 absorption, NH_3 temperature program desorption, CO temperature program desorption, and Raman techniques. Proper calcination temperature was effective to promote copper ions migration and diffusion, and led the support HMOR to possess more acid activity sites, which exhibited the complete decomposing of copper nitrate, large surface area and optimum micropore structure, more amount of CO adsorption site and proper amount of weak acid centers

Optimization of ultrasound-assisted extraction by response surface methodology, antioxidant capacity, and tyrosinase inhibitory activity of anthocyanins from red rice bran

The anthocyanins contents from red rice bran were characterized by HPLC/MS. Response surface methodology was used to optimize the ultrasound-assisted extraction of red rice bran anthocyanin. The antioxidant activities were evaluated in terms of IC50. The tyrosinase inhibitory activities of the anthocyanin samples from red rice bran and the standard substances were determined by a spectrophotometric method. According to mass spectrometry information, the main component of anthocyanins is paeoniflorin (m/z = 480). The optimized anthocyanin level was 5.80 mg/g under the following conditions: solid–liquid ratio of 1:17.46; ethanol concentration of 78.37%; ultrasonication time of 55.23 min; and pH of 2.31. The IC50 value of the DPPH radical scavenging and the superoxide anion scavenging activities of the sample were 53.51 and 2,375 μg/ml; those of the standard were 14.60 and 64.74 μg/ml; and those of vitamin C were 24.45 and 136.25 μg/ml, respectively. The IC50 values of the tyrosinase inhibition activities of the sample and Vc were 4.26 and 2.18 μg/ml, respectively. There is a significant difference (p < .05) between the activities of the three, which may be caused by the purity of the extract. Red rice bran anthocyanins have valuable research and development prospects as skin whiteners and healthcare products

Synthesis of Methyl Acetate by Dimethyl Ether Carbonylation over Cu/HMOR: Effect of Catalyst Preparation Method

Dimethyl ether carbonylation to methyl acetate was comparatively investigated over mordenite supported copper (Cu/HMOR) catalysts prepared by different methods including evaporation, urea hydrolysis, incipient wetness impregnation and ion-exchange. The results showed that Cu/HMOR prepared via iron-exchange method exhibited the highest catalytic activity due to the synergistic effect of active-site metal and acidic molecular sieve support. Conversion of 95.3% and methyl acetate selectivity of 94.9% were achieved under conditions of 210 ffiC, 1.5 MPa, and GSHV of 4883 h~(-1). The catalysts were characterized by nitrogen absorption, X-ray diffraction, NH_3 temperature program desorption, and CO temperature program desorption techniques. It was found that Cu/HMOR prepared by ion-exchange method possessed high surface area, moderate strong acid centers, and CO adsorption centers, which improved catalytic performance for the reaction of CO insertion to dimethyl ether

Aberrant functional connectivity for diagnosis of major depressive disorder : a discriminant analysis

Aim: Aberrant brain functional connectivity patterns have been reported in major depressive disorder (MDD). It is unknown whether they can be used in discriminant analysis for diagnosis of MDD. In the present study we examined the efficiency of discriminant analysis of MDD by individualized computer-assisted diagnosis. Methods: Based on resting-state functional magnetic resonance imaging data, a new approach was adopted to investigate functional connectivity changes in 39 MDD patients and 37 well-matched healthy controls. By using the proposed feature selection method, we identified significant altered functional connections in patients. They were subsequently applied to our analysis as discriminant features using a support vector machine classification method. Furthermore, the relative contribution of functional connectivity was estimated. Results: After subset selection of high-dimension features, the support vector machine classifier reachedup to approximately 84% with leave-one-out training during the discrimination process. Through summarizing the classification contribution of functional connectivities, we obtained four obvious contribution modules: inferior orbitofrontal module, supramarginal gyrus module, inferior parietal lobule-posterior cingulated gyrus module and middle temporal gyrus-inferior temporal gyrus module. Conclusion: The experimental results demonstrated that the proposed method is effective in discriminating MDD patients from healthy controls. Functional connectivities might be useful as new biomarkers to assist clinicians in computer auxiliary diagnosis of MDD