Effect of organic chelates on the performance of hybrid sol–gel coated AA 2024-T3 aluminium alloys

Sol–gels are organic–inorganic polymers formed by hydrolysis/condensation reactions of alkoxide precursors, primarily silanes, which have found applications as electronic, optical and protective coatings. These coatings possess important characteristics such as chemical stability, physical strength and scratch resistance. Further performance improvement is achieved through the incorporation of zirconium and titanium based nanoparticles, also formed through the sol–gel process. However due to the inherent difference in the reactivity of the precursors, the hydrolysis of each precursor must be carried out separately before being combined for final condensation. Zirconium precursors are commonly chelated using acetic acids, prior to hydrolysis, to lower the hydrolysis rate.In this body of work various ligands such as organic acids, acetyl acetone (AcAc) and 2,2′-bipyridine (Bipy) were used to control the zirconium hydrolysis reaction and form nanoparticles within the silane sol matrix.Nanoparticle modified coatings formed from the silane sol on AA 2024-T3 aluminium were characterised spectroscopically, electrochemically and calorimetrically to evaluate the potential effect of the different chelates on the final film properties while neutral salt spray tests were performed to study their anti-corrosion performance. Results indicate that the acid ligand modified coatings provided the best performance followed by AcAc, while Bipy was the poorest. In all cases the zirconium nanoparticle improved the protective properties of the sol–gel coating.     

Effect of key process variables on mechanical properties of blended vortex spun yarns

A study of significant factors and their interaction during vortex yarn spinning has been carried out to achieve desired mechanical properties of the polyethylene terephthalate/cotton blended yarns which can offer process and performance advantages. The key significant factors, i.e. feed ratio, air pressure and spindle size were varied in a mixed-level factorial design. The mechanical properties (count lea strength product, tenacity and elongation at break) were studied and feed ratio was found to significantly affect the tenacity and elongation at break of spun yarns. A significant effect of these parameters was observed on the diameter and hairiness of the Muratec vortex spun yarn.     

Image analysis of the porous yttria-stabilized zirconia (YSZ) structure for a lanthanum ferrite-impregnated solid oxide fuel cell (SOFC) electrode

Image analysis and quantification were performed on porous scaffolds for building SOFC cathodes using the two types of YSZ powders. The two powders (U1 and U2) showed different particle size distribution and sinterability at 1300?°C. AC impedance on symmetrical cells was used to evaluate the performance of the electrode impregnated with 35-wt.% La_0.8Sr_0.2FeO₃. For example, at 700?°C, the electrode from U2 powder shows a polarization resistance (R_p) of 0.21?Ω?cm², and series resistance (R_s) of 8.5?Ω?cm² for an YSZ electrolyte of 2-mm thickness, lower than the electrode from U1 powder (0.25?Ω?cm² for R_p and 10?Ω?cm² for R_s) does. The quantitative study on image of the sintered scaffold indicates that U2 powder is better at producing architecture of high porosity or long triple phase boundary (TPB), which is attributed as the reason for the higher performance of the LSF-impregnated electrode.     

Dependencies and autonomy in research performance: examining nanoscience and nanotechnology in emerging countries

Scientometrics - International collaboration in the creation of knowledge is changing the structural stratification of science, with implications for science policy. Analyses of collaboration in...     

Calcium peroxide (CaO2) for use in modified Fenton chemistry

The use of calcium peroxide (CaO2) powder as a source of H2O2 to promote modified Fenton (MF) chemistry was studied. First, the rate of production and yield of H2O2 from CaO2 dissolving in water at pH 6-9, and 12-13 (i.e., unbuffered CaO2) was measured. The rate of CaO2 dissolution increased as pH decreased, from 62 h for complete dissolution at pH 12-13 to only 4h at pH 6. The yield of H2O2 also increased with decreasing pH, from zero at pH 12-13 to 82% at pH 6. The ability of CaO2 to promote MF oxidation of PCE was demonstrated with a hydroxyl radical (OH) scavenger (2-propanol) at pH 8. The scavenger inhibited PCE oxidation, but 97% of the PCE was oxidized without it. Release of Cl(-) showed that PCE was mineralized. Finally, PCE oxidation was compared with liquid H2O2 (pH 7) and with CaO2 (pH 6, 7, 8, 9). Liquid H2O2 showed the lowest efficiency (mol H2O2 consumed/mol PCE oxidized) and the greatest temperature increase, disproportionation to O2, and PCE volatilization. CaO2 was a more efficient oxidant than liquid H2O2 at all pH values because it only releases H2O2 upon dissolution, reducing the loss to O2 and volatilization. CaO2 performed optimally at pH 8.     

Modeling of Pipe–Soil Interaction and Its Application in Numerical Simulation

This paper presents three plasticity models that can be applied to numerically simulate pipe–soil interaction. They can be applied individually to evaluate the force–displacement response of a small plane-strain pipe section or in combination to simulate a long pipeline system. In the latter, numerous pipe–soil elements are attached to structural finite elements, each simulating localized foundation restraint along the pipeline. The three models are increasing in sophistication, mainly due to the manner in which they account for the behavior within an allowable combined loading surface. The first is based on traditional strain-hardening plasticity theory and therefore assumes a purely elastic response inside a single expandable yield surface. The second allows some plasticity due to the use of a bounding surface, and the third accounts for kinematic hardening through the introduction of a second smaller surface. The models are detailed in this paper, allowing for simple numerical implementation. Importantly, they are incorporated within the structural analysis of a pipeline and their potential to investigate generic pipeline system behavior is demonstrated. The applicability of the three models is interpreted theoretically and their differences shown through application for (1) a one pipe–soil interaction element and along (2) a 100?m segment of pipeline. The latter shows the practical application of these models to offshore pipeline engineering examples, with the influence of a free span behavior investigated. The ability to model complex cyclic loading is also shown.     

Mediating between the muse and the masses: Inspiration and the actualization of creative ideas.

Within the creativity domain, inspiration is a motivational state posited to energize the actualization of creative ideas. The authors examined the construct validity, predictive utility, and function of inspiration in the writing process. Study 1, a cross-lagged panel study, showed that getting creative ideas and being inspired are distinct and that the former precedes the latter. In Study 2, inspiration, at the between-person level, predicted the creativity of scientific writing, whereas effort predicted technical merit. Within persons, peaks in inspiration predicted peaks in creativity and troughs in technical merit. In Study 3, inspiration predicted the creativity of poetry. Consistent with its posited transmission function, inspiration mediated between creativity of the idea and creativity of the product, whereas effort, positive affect, and awe did not. Study 4 extended the Study 3 findings to fiction writing. Openness to aesthetics and positive affect predicted creativity of the idea, whereas approach temperament moderated the relation between creativity of the idea and inspiration. Inspiration predicted efficiency, productivity, and use of shorter words, indicating that inspiration not only transmits creativity but does so economically. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced open-circuit voltage in organic photovoltaic cells with partially chlorinated zinc phthalocyanine

The open-circuit voltage (V _OC) in organic photovoltaic cells has been shown to depend on a number of parameters including the energy levels of the active materials, active layer structure, illumination intensity, and operating temperature. Here we report, a significant increase in V _OC from 0.43 to 0.63 V in zinc phthalocyanine (ZnPc)/C₆₀ planar heterojunction photovoltaic cells operated at room temperature under 1 sun AM1.5G solar illumination, when a home-synthesized and purified ZnPc source materials was used instead of a commercially obtained (and home purified) ZnPc source. While the two ZnPc source materials have nearly identical UV–Vis and IR absorption properties, the home-synthesized ZnPc contains chlorinated derivatives and has half of the electrical defect density (on the order of 10¹⁶ cm^?3) as compared to the commercial ZnPc. The improved V _OC in devices with the home-synthesized ZnPc is contributed from both a lower dark current and a higher magnitude of photocurrent. Additional experiments revealed that the different device characteristics are mostly associated with processes occurring at the ZnPc/C₆₀ interface, which we attribute to nongeminate recombination of charges built-up on either side of the interface.     

Recording of electric signal passing through a pylon in direct skeletal attachment of leg prostheses with neuromuscular control

Direct recordings were made of electrical signals emanating from the muscles in a rabbit's residuum. The signals were transmitted via wires attached on one end to the muscles, and on the other to an external recording system. The cable was held in a titanium tube inside a pylon that had been transcutaneously implanted into the residuum's bone. The tube was surrounded by porous titanium cladding to enhance its bond with the bone and with the skin of the residuum. This study was the first known attempt to merge the technology of direct skeletal attachment of limb prostheses with the technology of neuromuscular control of prostheses, providing a safe and reliable passage of the electrical signal from the muscles inside the residuum to the outside recording system.