11B and 15N solid state NMR investigation of a boron nitride preceramic polymer prepared by ammonolysis of borazine

A poly(aminoborazine), precursor for hexagonal boron nitride (h-BN) obtained by reaction of borazine B₃N₃H₆ with ammonia, and its pyrolysis derivatives have been extensively characterised by ¹⁵N and ¹¹B MAS NMR. The various B and N sites have been identified according to their first neighbouring atoms, as well as to the second ones in the case of ¹⁵N, and have also been quantified. This study demonstrates that a suitable choice of NMR techniques together with the use of isotopic enrichment can lead to a large improvement in spectral resolution, which allows a better understanding of such complex BN preceramic polymer structures and permits to follow the polymer-to-ceramic transformation.     

The influence of preparation method on the properties of NiMo sulfide catalysts supported on ZrO2

Highly loaded supported (Ni)Mo sulfide catalysts prepared using different methods have been studied. Two zirconia supports of high specific surface area were used, including amorphous or tetragonal ZrO₂ solids. The order of active components introduction as well as thermal treatment conditions were varied. The best performance in the reactions of hydrodesulfurisation of thiophene and hydrogenation of tetralin was shown by the coimpregnated systems sulfidized without calcination of the oxide precursor. Crystallized ZrO₂ support always provides higher activities in both reactions, than amorphous zirconia, despite very high specific surface area of the last. The differences between variously treated systems were explained using the results of characterizations including laser Raman spectroscopy, XPS spectroscopy and temperature programmed reduction.     

Deformation behaviour of iron-doped alumina

Compressive creep tests in air were carried out on 1 cat.% Fe-doped alumina at a temperature T=1400 °C. Iron doping affected the plastic deformation by different ways in relation with Fe²⁺ cations population. Fe²⁺ cations sped up the deformation rates. FeAl₂O₄ spinel precipitates were identified and they were found (i) to interact with alumina grain boundaries (ii) to limit the grain growth within a range of strain. The Fe²⁺ cations underwent oxidation and this resulted in the dissolution of the some precipitates and in the decrease of deformation rates. It was suggested that deformation sped up this evolution through mass transport and that time was not a dominating parameter.     

Electrical properties of dysprosium phthalocyanine films

Forty-four nanometers thick films of alkyl-substituted dysprosium phthalocyanine molecules were prepared on carefully cleaned indium tin oxide (ITO) substrates by the spin casting method. UV–vis absorption spectra and dc conduction characteristics were obtained in order to investigate the structure–conduction property relationship. The conduction is Ohmic at low applied voltages but the space charge limited mechanism is prevalent at relatively high voltages. The conductivities of both as-deposited and heat treated films are found to show directionally anisotropic behaviour. The columnar conductivity was found to be significantly large in the liquid crystalline state.     

Global experience curves for wind farms

In order to forecast the technological development and cost of wind turbines and the production costs of wind electricity, frequent use is made of the so-called experience curve concept. Experience curves of wind turbines are generally based on data describing the development of national markets, which cause a number of problems when applied for global assessments. To analyze global wind energy price development more adequately, we compose a global experience curve. First, underlying factors for past and potential future price reductions of wind turbines are analyzed. Also possible implications and pitfalls when applying the experience curve methodology are assessed. Second, we present and discuss a new approach of establishing a global experience curve and thus a global progress ratio for the investment cost of wind farms. Results show that global progress ratios for wind farms may lie between 77% and 85% (with an average of 81%), which is significantly more optimistic than progress ratios applied in most current scenario studies and integrated assessment models. While the findings are based on a limited amount of data, they may indicate faster price reduction opportunities than so far assumed. With this global experience curve we aim to improve the reliability of describing the speed with which global costs of wind power may decline.     

Photocatalytic evolution of hydrogen over mesoporous TiO2 supported NiO photocatalyst prepared by single-step sol–gel process with surfactant template

Photocatalytic activity of mesoporous titania supported nickel oxide photocatalyst synthesized by single-step sol–gel (SSSG) process combined with surfactant-assisted template method was investigated for hydrogen evolution from an aqueous methanol solution, in comparison with one prepared by conventional incipient wetness impregnation (IWI) method. In single-step sol–gel process, nickel precursor was introduced into the titania sol prepared with the aid of a surfactant template behaving as pore-controlling agent to attain meso-scaled pore. The single-step sol–gel photocatalyst was experimentally found to enhance the photocatalytic evolution of hydrogen rather than the impregnated one. The optimum level of nickel loading in photocatalytic activity test for single-step sol–gel method was slightly higher than that for incipient wetness impregnation method. Characterization results demonstrated the significant modification of physical characteristics of the single-step sol–gel photocatalyst, anticipated to relating to the observation of higher photocatalytic hydrogen evolution activity.     

Microwave Demulsification in Removing Naphthenic Acids from Diesel Oil

Emulsification is an undesired phenomenon in the refining of highly acidic oil by alkali-washing electro-refining. In this article, a novel microwave method is applied for demulsification in the removing of naphthenic acid from diesel oil. The internal heating is attributed to molecular rotation and ionic conduction. The decrease of interface zeta-potential and the viscosity of diesel oil are responsible for the demulsification with microwave irradiation. The results exhibited that the demulsification rate is maximized when the optimum microwave irradiation power, exposure time, and irradiation pressure for Anshan and Liaohe diesel oil are deemed to be 375 W, 5/6 min and 0.05 MPa, respectively.     

Fabrication and characterization of TiO2/short MWNTs with enhanced photocatalytic activity

TiO₂/short MWNTs nanocomposites were prepared by the sol–gel method using butyl titanate and short MWNTs as starting materials in the solvent of isopropyl alcohol. Their photocatalytic activity in the degradation of X-3B was studied. The effects of mass ratio of short MWNTs to butyl titanate, and heat-treatment temperature on the photoactivity of TiO₂/short MWNTs nanocomposites were discussed. For comparison purpose, other photocatalysts were also employed in the photodegradation experiment. Thermogravimetric–differential thermal analysis (TG–DTA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV–Vis absorption spectra were utilized to characterize the prepared photocatalysts. The results showed that the TiO₂/short MWNTs nanocomposites synthesized with 1% mass ratio of short MWNTs to butyl titanate had the best photoactivity.     

Bonelike apatite formation on carbon microspheres

Carbon microspheres with a diameter of 2 μm were prepared by hydrothermal process. The apatite-formation ability of the carbon microspheres was evaluated by soaking them in a simulated body fluid (SBF) for 5 and 10 d and apatite-formation mechanism was also analyzed. The result showed that bonelike apatite was formed on the surface of carbon microspheres. Our study indicates that the carbon microspheres synthesized by this method possess apatite-formation ability and may be used as a bioactive injectable filler for bone tissue regeneration.