Superior electromechanical performance over PZT, in lead zinc niobate (PZN)–lead zirconium titanate (PZT) thin films

Strongly oriented thin films of lead zinc niobate (PZN)–lead zirconium titanate (PZT) with (La,Sr)CoO₃ lower electrodes were grown on MgO {001} substrates by pulsed laser deposition. The films were perovskite-dominated with strong in-plane and out-of-plane orientations. Room-temperature functional characterisation indicated that the films were ferroelectric, with dielectric constant ∼550 and loss tangent ∼0.08 at 1 kHz. The crystallographic strain, as a function of applied dc field, was monitored by in situ X-ray diffraction. The maximum electric-field-induced crystallographic strain (∼0.22%) was comparable to that observed in bulk, but at significantly greater field (∼150 kV cm^-1). The effective d₃₃ value obtained from the crystallographic strain data was around 150 pm V^-1, which is high for ferroelectric thin films 400 nm in thickness. The local polarisation-switching properties of the films were investigated using a piezo-response atomic force microscope. Domain maps for a 5×5 μm² region of material were recorded as a function of dc bias, and confirmed the ferroelectric switching behaviour. PACS 81.05.Je; 81.40.Vw; 68.37.Lp     

Development of Molecular Mechanics Torsion Parameters for alpha,beta-Cyclopropyl Ketones and Conformational Analysis of Bicyclo[m.1.0]alkan-2-ones

Conformations of cyclopropyl methyl ketone have been studied using ab initio methods in an effort to quantify the effects of conjugative overlap between the cyclopropane ring and an adjacent ketone carbonyl. Results were comparable with previous experimental and theoretical studies. Cyclopropyl methyl ketone exhibits a global energy minimum in the s-cis conformer and a local energy minimum near the s-trans conformer. The potential energy curve obtained was used to derive torsion parameters which were employed in molecular mechanics studies of the conformations of the set of bicyclo[m.1.0]alkan-2-ones having larger ring sizes from five- to 16-membered. Similar conformations for the cyclopropyl ketone substructure are observed for all the medium and large ring systems examined. Possible synthetic ramifications of local conformational anchoring by this functional group array are discussed.     

Experimental study of wall curvature and bypass flow effects on orifice discharge coefficients

This paper presents the results of an experimental study investigating the impact of wall curvature and bypass flow on the discharge coefficients of circular orifices. To extend the range of currently available discharge coefficients, the ratio of the orifice to the pipe diameter is varied from 0.25 to 0.67. Functional relationships are developed that relate a free-discharge orifice coefficient to the ratio of the orifice diameter to the pipe diameter and the total head (velocity and pressure heads) upstream of the orifice. In addition, the use of the projected area versus surface area of the orifice for determining discharge coefficients is investigated and the results show that both approaches yield similar observations. The results of this experimental study are particularly useful for the case of sparger design.     

Assessing the emerging biorefinery sector in Canada

The biorefinery is a key concept used in the strategies and visions of many industrial countries. The potential for Canadian biorefineries based on lignocellulosic forest and agricultural residues is examined. The sector is described in terms of research interests, emerging companies, and established corporate interests. It is found that the Canadian biorefining sector currently has an emphasis on specific bioproduct generation, and the process elements required for a true sugar-based process are in the research phase. A Canadian national strategy should focus on increasing forest industry participation, and increasing collaboration with the provinces, particularly in western Canada.     

Enzymatic hydrolysis of steam-exploded and ethanol organosolv-pretreated douglas-fir by novel and commercial fungal cellulases

Softwood residues are the most abundant feedstock available for bioconversion in many northern countries. However, the high costs for delignification and enzymatic hydrolysis currently deter commercialization of softwood bioconversion processes. This study evaluates the abilities of two novel fungal preparations (MSUBC1 and MSUBC2) and two commercial cellulase preparations (TR1 and TR2) to hydrolyze cellulose in Douglas-fir pretreated by steam explosion or ethanol organosolv process. MSUBC1 showed significantly better performance than the other preparations on both lignocellulosic substrates. In particular, MSUBC1 achieved >76% cellulose conversion for hydrolysis of steam-exploded Douglas-fir (～44% lignin) after 72 h at low enzyme loading (10 filter paper units/g of cellulose) and without β-glucosidase supplementation.     

Phase equilibria of poly(ethylene-co-vinyl acetate) copolymers in subcritical and supercritical ethylene and ethylene---vinyl acetate mixtures

Experimental high-pressure phase equilibrium data (cloud point and coexistence data) are reported for solutions of commercial poly(ethylene---co-vinyl acetate) samples in supercritical ethylene and ethylene---vinyl acetate (VA) mixtures. These data are correlated with an equation of state rooted in statistical associating fluid theory (SAFT). SAFT captures the effects of polymer MW, incorporated VA%, and free VA on the cloud point pressure, and on the size of the fluid-liquid miscibility gap, over a broad range of temperatures (50–250°C) and polymer concentrations. Free VA is found to behave as a cosolvent (lowering the cloud point pressure), except at low temperatures (< 100°C) and with low VA-containing copolymers, in which case free VA, if present in large excess (> 70 wt.%), behaves as a polar antisolvent due to favorable self-interactions among the free VA molecules. SAFT predicts a shift in the phase transition type, from upper-critical-solution-temperature (UCST), to upper-lower-critical-solution-temperature (U-LCST) with increasing free VA in the monomer mixture.     

Integration of fuzzy linguistic information in language comprehension

To successfully understand a natural language utterance, a person must simultaneously consider information about its perceptual, syntactic, semantic, and pragmatic structure. At each of these levels of analysis, the linguistic information is continuously but systematically variable. It is argued that in order to cope with and, in fact, exploit this continuous information requires fuzzy propositional representations of linguistic knowledge. Such a fuzzy propositional theoretical framework is proposed and models of several specific language processing components are developed and empirically evaluated within this framework. The model system incorporates many of the major principles of current cognitive psychological theory and extends them into the fuzzy domain.