Do global risk perceptions influence world oil prices?

This paper investigates the information transmission mechanism between world oil, gold, silver, dollar/euro exchange rate markets, and volatility index (VIX) accommodating for global risk perceptions. We find that there is a unique long run equilibrium relationship, where gold, silver, exchange rate, and risk perceptions appear as long run forcing variables of world oil prices. We uncover that global risk perceptions have a significantly suppressing effect on oil prices in the long run. We also discover that global risk perceptions play a less important role in explaining the forecast error variance of oil prices in the short run, than prices in the alternative investment markets. Our results also suggest that a shock in risk perceptions of global investors have a negative but short lived initial impact on oil prices.     

Complexes Containing N-(2-hydroxyethyl)-ethylenediamine with Tetracyanometallate (II): Synthesis, IR Spectra, Thermal Behavior, Crystal Structure, Magnetic Properties and Catalysis

Two novel cyano-bridged Ni²⁺ and Cu²⁺ compounds, {[M²⁺(hydeten)₂(μ-CN)₂Ni(CN)₂] _n , M²⁺ = Ni²⁺ (c1) and Cu²⁺ (c2), N-(2-hydroxyethyl)-ethylenediamine (hydeten), were prepared and characterized by elemental analysis, IR spectroscopy and thermoanalytical measurements. The one-dimensional polymeric structure of c2, which was determined by X-ray diffraction techniques, was formed with a 2,2-TT-type chain, –Cu(hydeten)₂-NC-Ni(CN)₂-CN-Cu(hydeten)₂-, linkages. Also, while the EPR spectra and magnetic properties of complexes c1 and c2 with [Ni(hydeten)₂Pd(CN)₄] (c3) and [Cu(hydeten)₂Pd(CN)₄] (c4) [Karadağ, Z Kristallogr 222:39, 2007] were investigated, the catalytic activity of c3 and c4 was studied. The EPR spectra of c2 and c4 showed that Cu²⁺ was located in tetragonal distorted octahedral sites (D _4h ) and the ground state of the paramagnetic electron was d _{x² - y²} d_{{ x^{2} - y^{2} }} . The magnetic behavior exhibited weak antiferromagnetic interactions in all the complexes. Also, the catalytic properties of c3 and c4, which were assigned with Suzuki and Heck coupling reactions, showed that they did not have catalytic effects.     

Three-dimensional nickel nanodomes: Efficient electrocatalysts for water splitting

Highly efficient and stable three-dimensional (3D) Ni nanodome (Ni-NDs) arrays were fabricated as candidate cathode materials for alkaline water splitting. The NDs were prepared by a combined methods of soft lithography-nanosphere lithography, physical vapor deposition (PVD) and electrochemical deposition using polydimethylsiloxane (PDMS) as template. The water splitting activity of the 3D nanostructures were examined in 6 M KOH solution using polarization and electrochemical impedance spectroscopy techniques. The data obtained showed that well-structured and uniformly distributed Ni-NDs could be fabricated using this combined method. The ND arrays perform excellent hydrogen evolution activity with respect to Ni plate as a reference point since their nano-sized roughness results in larger real surface area. By comparing with Ni plate, lower hydrogen onset potential (85 mV) and charge transfer resistance (90.1%) as well as higher current density (90.4%) corresponding to the amount of evolved hydrogen were observed at the NDs. The Ni-NDs have high time-stability in the electrolysis conditions. It is believed that the Ni-ND arrays contribute to the design of novel electrocatalytic electrodes as candidate supporting materials.     

Investigating the effects of surface superhydrophobicity on moisture ingression of nanofiber-reinforced bio-composite structures

Superhydrophobic coatings have been involved in many industrial applications because they exhibit high water repellency. These coatings can usually improve the surface properties of materials by reducing corrosion, adhesion, deicing, defrosting, and wetting, and increasing self-cleaning. In this study, superhydrophobic coatings were applied on the surfaces of carbon, Kevlar, and glass fiber composites to eliminate the absorption of moisture into the composite structures. The superhydrophobic coatings consist of two coats: bottom (or base) and top. The coated composite coupons were subjected to moisture ingression tests in deionized water until the samples reach their moisture equilibrium, which may vary between 4 and 6 weeks, and then the ingression tests were compared with the bare composite coupons. The water contact angles (WCAs) and thicknesses of the composite samples were measured at the beginning and end of the tests. The moisture gain of all composite coupons was measured as a function of immersion times. Heat treatment tests were performed on the samples to observe the moisture gain. In order to characterize the coated surfaces, WCA tests and Fourier transform infrared spectrometry analyses were also conducted. Test results demonstrated that when the surface of composites was coated with superhydrophobic coatings, the moisture absorption was much less in comparison to the non-coated composite coupons. This study can provide several benefits to the composite industry in general, and the aircraft and wind turbine industries in particular, in terms of moisture elimination, weight savings, and structural integrity of composites.

     

Preparation of amidoximated polyester fiber and competitive adsorption of some heavy metal ions from aqueous solution onto this fiber

In this study, a fibrous adsorbent containing amidoxime groups was prepared by graft copolymerization of acrylonitrile (AN) onto poly(ethylene terephthalate) (PET) fibers using benzoyl peroxide (Bz₂O₂) as initiator in aqueous solution, and subsequent chemical modification of cyano groups by reaction with hydroxylamine hydrochloride in methanol. The grafted and modified fibers were characterized by FTIR, TGA, SEM, and XRD analysis. The crystallinity increased, but thermal stability decreased with grafting and amidoximation. The removal of Cu(II), Ni(II), Co(II), Pb(II), and Cd(II) ions from aqueous solution onto chelating fibers were studied using batch adsorption method. These properties were investigated under competitive conditions. The effects of the pH, contact time, and initial ion concentration on the removal percentage of ions were studied. The results show that the adsorption rate of metal ions followed the given order Co(II) > Pb(II) > Cd(II) > Ni(II) > Cu(II). The percentage removal of ions increased with initial ion concentration, shaking time, and pH of the medium. Total metal ion removal capacity was 49.75 mg/g fiber on amidoximated fiber. It was observed that amidoximated fibers can be regenerated by acid without losing their activity, and it is more selective for Pb(II) ions in the mixed solution of Pb‐Cu‐Ni–Co‐Cd at pH 4. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Applications of quantum dots in optical fiber luminescent oxygen sensors

The potential applications of luminescent semiconductor nanocrystals to optical oxygen sensing are explored. The suitability of quantum dots to provide a reference signal in luminescence-based chemical sensors is addressed. A CdSe-ZnS nanocrystal, with an emission peak at 520 nm, is used to provide a reference signal. Measurements of oxygen concentration, which are based on the dynamic quenching of the luminescence of a ruthenium complex, are performed. Both the dye and the nanocrystal are immobilized in a solgel matrix and are excited by a blue LED. Experimental results show that the ratio between the reference and the sensor signals is highly insensitive to fluctuations of the excitation optical power. The use of CdTe, near-infrared quantum dots with an emission wavelength of 680 nm, in combination with a ruthenium complex to provide a new mechanism for oxygen sensing, is investigated. The possibility of creating oxygen sensitivity in different spectral regions is demonstrated. The results obtained clearly show that this technique can be applied to develop a wavelength division multiplexed system of oxygen sensors.     

Photocatalytic hydrogen production by water splitting over Au/Al-SrTiO3

Visible light water splitting activity of Au-Al/SrTiO₃ was tested in this work. Al/SrTiO₃ was synthesized via solid state reaction while Au loading was done with homogenous deposition precipitation method. The effects of Au loading and Al doping were investigated in 10, 20 and 30% aqueous solutions of methanol, ethanol, and isopropyl alcohol. The methanol was performed better over 0.25%Au-1.0%Al/SrTiO₃ at 20% alcohol concentration while the isopropyl alcohol resulted in better performance over the same catalyst at 30% concentration; the latter was also the best result obtained in this work with the hydrogen evolution rate of 347 μmol/h.gcat. Ethanol showed lower performance than other two alcohols. It was found from UV–vis analysis that Al doping increased the band energy of SrTiO₃. XRD and XPS analyses clearly showed that the dominant structure was SrTiO₃ in all samples. Au was found to be generally loaded as 30–40 nm particles by SEM.     

The effect of 3D silver nanodome size on hydrogen evolution activity in alkaline solution

Three-dimensional (3D) Ag nanodomes (AgNDs) having different sizes (400, 800, 1200 and 1600 nm) were fabricated using combination of nanosphere lithography and soft lithography. The surface structures of 3D assembled latex particles, nanovoids and metal nanodomes (ND) were examined using scanning electron microscopy (SEM). Their heights and widths analyses were performed with the help of atomic force microscopy (AFM). The effect of diameter of the NDs on their hydrogen evolution activity was examined in 6 M KOH solution at 298 K using electrochemical techniques. Their activities were compared with the activity of bulk Ag electrode. The preparation of 3D-AgNDs having various diameters and examination of their size effects on the water splitting activity have not been studied yet and are being reported firstly. It was found that very well-structured and very uniformly distributed NDs can be fabricated using this procedure. AgNDs exhibit higher hydrogen evolution activity with respect to bulk Ag. Their hydrogen evolution activity depends on their diameters; 1200 nm NDs were the best among them. The current density at ?1.40 V(Ag/AgCl) which is proportional to the rate of hydrogen releasing reaction increases from 0.70 mA cm^?2 to 44.13 mA cm^?2 at this ND electrode with respect to the bulk Ag electrode. At the same 3D-AgNDs electrode and potential, the resistance against the HER reduces from 148.7 Ω cm² to 1.12 Ω cm² (99.6%) by comparing with the bulk Ag electrode. The average surface roughness factors of bulk Ag, 400 nm, 800 nm, 1200 nm and 1600 nm AgNDs are 8, 123, 100, 291 and 176, respectively. The superior hydrogen evolution performance of this electrode is related to its well-structured surface and large real surface area.     

Application of the homotopy method for the analytic approach of the nonlinear free vibration analysis of the simple end beams using four engineering theories

In this paper, nonlinear vibration analyses of Euler–Bernoulli, Rayleigh, Shear and Timoshenko beams with simple end conditions are presented using homotopy analysis method (HAM). Closed form solutions for natural frequencies, beam deflection, post-buckling load–deflection relation, and critical buckling load are presented. The calculated natural frequencies for all four cases were verified against some available results in the literature and very good agreement observed. Furthermore, obtained results for deflection, buckling, and post-buckling of each beam are presented and the effects of some parameters, such as slenderness ratio, the rotary inertia, and the shear deformation are examined.