Solubility of Hydrogen Sulfide in [bmim][PF<Subscript>6</Subscript>]

New experimental data are presented for the solubility of hydrogen sulfide in the ionic liquid 1-N-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]) at five temperatures in the range (298–403) K at pressures up to 9.6 MPa. The ionic liquid [bmim][PF₆] is a good solvent for hydrogen sulfide. At 9 MPa the mole fraction H₂S in the liquid is about 0.7. The solubility is a strong function of temperature; at 2 MPa the solubility (mole fraction H₂S) decreases from about 0.84 at 298 K to about 0.2 at 403 K. The Krichevsky–Kasarnovsky equation was used to correlate the experimental data, and Henry’s constants were obtained. The solution thermodynamic properties at standard temperature and pressure were calculated.     

Novel pixel design for high‐resolution AMOLED displays with a shadow mask

Abstract— The bottlenecks in achieving high resolution for active‐matrix OLED (AMOLED) displays based on currently available manufacturing processes were evaluated and compared. The use of a shadow mask has proven to be viable for mass production, but the fabrication of high‐precision shadow masks becomes very difficult when the resolution exceeds 180 ppi. The latest breakthrough in increasing display resolution is presented. Without an increase in cost, the limitations of the conventional shadow‐mask process using novel subpixel designs have been successfully overcome. A high resolution reaching of 270 ppi has been successfully demonstrated on a 3‐in. VGA‐format AMOLED display, fabricated by using a shadow mask with a much lower resolution of 135 ppi. This innovative pixel design opens up the possibilities of manufacturing high‐resolution displays using a relatively low‐resolution shadow mask.     

Effect of blend composition on the morphology development of electrospun fibres based on PAN/PMMA blends

BACKGROUND: The aim of the work presented was to determine the morphology development and relevant change in fibre diameter of a binary polymer blend system during an electrospinning process. The size of the fibre diameter is one of the important factors determining the general properties of non‐woven mats formed from electrospun fibres. RESULTS: The morphology and diameter of electrospun polyacrylonitrile (PAN)/poly(methyl methacrylate) (PMMA) blends were investigated as a function of blend ratio using scanning electron microscopy. The diameter of the electrospun PAN/PMMA fibres decreased with increasing PMMA content up to 50 wt%, and then increased again with further increase of PMMA. After thermal treatment, the fibres shrank, and an irregularly shaped morphology was observed. CONCLUSION: The electrospinning of incompatible PAN/PMMA blends leads to a microphase‐separation morphology of fibres. A phase inversion occurs at a PMMA content of between 50 and 75 wt%. Due to the phase inversion, the fibre diameter shows a minimum value at the relevant composition. Copyright © 2008 Society of Chemical Industry     

Growth of single-crystal W whiskers during humid H2/N2 reduction of Ni, Fe–Ni, and Co–Ni doped tungsten oxide

Numbers of W whiskers were obtained by reducing Ni, Ni–Fe, and Ni–Co doped tungsten oxide in a mixed atmosphere of humid H₂ and N₂. The phases and morphologies of the reduction products were characterized by XRD and SEM. Intensive TEM and EDS analyses showed that the obtained whiskers were W single crystals which typical have alloyed particles (Ni–W, Fe–Ni, or Co–Ni–W) at the growth tips. The formed W whiskers were presumed to be induced by the alloyed particles. Our experimental results revealed that, during the reduction process of tungsten oxide, the pre-reduced Ni, Fe–Ni, or Co–Ni particles not only served as nucleation aids for the initial growth of W phase from W oxide but also played the roles of catalysts during the reductive decomposition of gaseous WO₂(OH)₂.     

Doppler frequency shift estimation for differentially coherent CPM

A communication scheme based on continuous-phase modulated (CPM) signals used in conjunction with trellis-coded modulation (TCM) is considered. To keep the complexity manageable, a detection scheme based on differential detection of CPM signals is used. Methods that estimate the Doppler-induced frequency shift from the receiver signal are studied. Since differential detection transforms a frequency shift into a phase shift, the phase estimation problem is examined first. Three Doppler frequency estimation schemes that are based on open-loop structures and that are designed to achieve different ranges of Doppler frequencies that can be estimated are introduced. These estimators show different degrees of complexity and (at least for high signal-to-noise ratios) significantly different estimation errors. Their performance is compared by using a simulation approach     

High temperature creep in polycrystalline AIN-SiC ceramics

Polycrystalline dense ceramic specimens containing 75 mol % AIN-25 mol % SiC and 60 mol % AIN-40 mol % SiC were subjected to creep deformation in bending at elevated temperatures. Over the range of temperatures and stresses investigated, the creep rate was found to vary linearly with stress indicative of diffusional creep. Creep was found to be thermally activated with activation energy in the range from 175 kcal mol⁻¹ to 219 kcal mol⁻¹. Electron microscopic observation indicated that crack like cavities formed near the tensile surfaces during creep.