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With the help of hydrogen bonding and π⋯π stacking, the small molecular clusters in the impregnating solution was induced to self-assemble and form a new Ni–Mo polyoxometalate based on octamolybdate with a molecular formula of [Ni(pyz)6] [Mo8O26(pyz)2]⋅10H2O (pyz = pyrazole). The polyoxometalate was structurally characterized detailed by various technologies, and its sulfide was also characterized to make a preliminary study to explore the use of it as a potential NiMoS active phase precursor. Much more NiMoS active phase and higher catalytic activity of the Ni–Mo sulfided catalyst was found, and the structure-directing effects can account for the phenomenon. The results show the Ni–Mo polyoxometalate [Ni(pyz)6] [Mo8O26(pyz)2]⋅10H2O can make a superior precursor to prepare the hydrodesulfurization catalyst, and it provides a new preparation methodology to the rational design and controllable preparation of superior hydrodesulfurization catalysts. [ABSTRACT FROM AUTHOR]

The electrocatalysts utilized as the prospective electrodes in fuel cells and high efficient energy conversion devices require both the interconnected channels for efficient electrolyte transportation and the superior catalytic activity with long service life. In this work, nanoporous gold with the rigid skeletons in three dimensions is partially decorated by porous platinum shell containing nanoscale interstitials, aiming to create the heterogeneous gold-platinum interfaces and facilitate the electrolyte transportation as well. In comparison with no catalytic activity of bare nanoporous gold, the catalytic activity of hierarchical nanoporous gold-platinum towards electrochemical oxidation of methanol increases with the loading level of platinum shells, resulting in the highest electrochemical area of 70.4 m2·g-1 after the normalization by the mass of platinum. Heterogeneous gold-platinum interfaces affect the tolerance of the absorbed intermediate species because of the oxidization by the oxygenated species absorbed on the gold surface and the enhanced ion transportation within the porous platinum shell. [ABSTRACT FROM AUTHOR]

A novel strategy to synthesize nitrogen (N) and sulfur (S)-doped graphene (G) is developed through sulfate-reducing bacteria treating graphene oxide (GO). The N, S-doped G demonstrates significantly improved electrocatalytic properties and electrochemical sensing performances in comparison with single-doped graphene due to the synergistic effects of dual dopants on the properties of graphene. [ABSTRACT FROM AUTHOR]

We report a facile and green method to synthesize a new type of catalyst by coating Pd nanoparticles (NPs) on reduced graphene oxide (rGO)-carbon nanotube (CNT) nanocomposite. An rGO-CNT nanocomposite with three-dimensional microstructures was obtained by hydrothermal treatment of an aqueous dispersion of graphene oxide (GO) and CNTs. After the rGO-CNT composites have been dipped in K2PdCl4 solution, the spontaneous redox reaction between the GO-CNT and PdCl4 2- led to the formation of nanohybrid materials consisting rGO-CNT decorated with 4 nm Pd NPs, which exhibited excellent and stable catalytic activity: the reduction of 4-nitrophenol to 4-aminophenol using NaBH4 as a catalyst was completed in only 20 s at room temperature, even when the Pd content of the catalyst was 1.12 wt%. This method does not require rigorous conditions or toxic agents and thus is a rapid, efficient, and green approach to the fabrication of highly active catalysts. [ABSTRACT FROM AUTHOR]

Ni-promoted tetramethylammonium tetrathiomolybdate precursor was prepared by the aqueous solution precipitation method using (NH4)2MoS4, (CH3)4NBr and NiCl2.6H2O as raw materials. Carbon-containing Ni–Mo sulfide nanospheres, namely Ni/C1–MoS2, were obtained by ex situ thermal decomposition of the precursor under N2 atmosphere. Energy dispersive X-ray spectroscopy (EDS), low temperature N2 adsorption (BET method), X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) techniques were employed to characterize these as–synthesized sulfide particles. The results showed that the average size of solid Ni–Mo sulfide nanospheres, with surface composition MoNi0.40S0.73C1.43, is 75 nm and the solid structure leads to low surface area of Ni/C1–MoS2. In addition, the introduction of methyl chain improved the dispersion of nickel phases and resulted in C/Mo ratio, 1.4. By comparison with catalytic performance of the Ni/MoS2 catalyst counterpart, Ni/C1–MoS2 revealed lower HDS activity but higher direct desulfurization (DDS) selectivity. Lower stacking number of MoS2 slabs (5 layers) and shorter slabs length of MoS2 slabs (6 nm) explained higher DDS selectivity satisfactorily. The formation of carbon-containing Ni–Mo sulfide nanospheres was possibly due to surfactant effect of tetramethylammonium cations and the potential measure to increase their surface area was discussed as well in this work. [ABSTRACT FROM AUTHOR]

In this work the equation of circular loops of cosmic string possessing time-dependent tension is studied in the de Sitter spacetime. We find that the cosmic string loops with initial radius r( t0)>0.707 L, L de Sitter radius, should not collapse to form a black hole. It is also found that in the case of r( t0)<0.707 L a loop of cosmic string whose tension depends on some power of cosmic time can not become a black hole if the power is lower than a critical value which is associated with the initial size of the loop. Our research gives rise to some important corrections to the conclusion in the case of loops of cosmic string with constant tension in the same background. [ABSTRACT FROM AUTHOR]

A photonics true-time-delay system for phased array antenna beam steering employing a novel tunable chirped fiber grating delay line and a multiwavelength erbium-doped fiber ring laser source based on a sampled grating filter is proposed. The tunable chirped fiber grating, which act as a continuous time-delay element, is achieved by bending a uniform fiber Bragg grating bonded at a slant onto the lateral surface of a simply supported beam. This technique allows the dynamic control of the chirp rate and spectral width of the grating without center wavelength shift. By adjusting the chirp rate of the fiber grating via bend strain, this kind of tunable chirped fiber grating could achieve very low and adjustable delay times, therefore provides higher angle resolution for scanning microwave beam, even the wavelengths of laser source are fixed and un-tunable. The true-time-delay system using proposed tunable chirped fiber grating delay element and sampled grating based laser source is constructed and demonstrated experimentally. [ABSTRACT FROM AUTHOR]

Focuses on a study which explored the electron structures and non-linear optical properties of tertbutyl-nitro-phthalocyanines. Methodology; Results and discussion; Conclusion.

Discusses the synthesis of a series of pentacoordinate substituted p-benzoate bis(8-hydroxyquinaldine) gallium complexes. Fig. 1). Characterization of the structure of complexes was characterized by element analysis; Effect of the substituted group of second ligand; Preparation of gallium benzoate complex.

A correction to the article "Timing of Cyclin D1 Expression Within G1 Phase Is Controlled by Rho" that was published online in the October 5, 2001 issue is presented.