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We describe the fabrication and characterization of tungsten oxide nanofibers using the electrospinning technique and sol-gel chemistry. Tungsten isopropoxide sol-gel precursor was incorporated into poly(vinyl acetate)(PVAc)/DMF solutions and electrospun to form composite nanofibers. The as-spun composite nanofibers were subsequently calcinated to obtain pure tungsten oxide nanofibers with controllable diameters of around 100 nm. SEM and TEM were utilized to investigate the structure and morphology of tungsten oxide nanofibers before and after calcination. The relationship between solution concentration and ceramic nanofiber morphology has been studied. A synchrotron-based in situ XRD method was employed to study the dynamic structure evolution of the tungsten oxide nanofibers during the calcination process. It has been shown that the as-prepared tungsten oxide ceramic nanofibers have a quick response to ammonia with various concentrations, suggesting potential applications of the electrospun tungsten oxide nanofibers as a sensor material for gas detection.

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A set of powerful x-ray imaging techniques using white-beam synchrotron radiation have been developed and applied to clearly reveal and map micropipes in SiC crystals at a “magnified” level. The experimental results and the corresponding simulations demonstrate explicitly that the micropipes are pure superscrew dislocations (SSDs). Moreover, these techniques provide accurate descriptions of the detailed structure of the SSDs, including the spatial distribution of the strain fields, the magnitudes of the Burgers vectors, the dislocation senses, and the surface relaxation effects.

This study investigated psychological correlates of depression in fathers and mothers in the first postnatal year, using a mixed, mainly clinically referred sample and a cross-sectional design. The Edinburgh Postnatal Depression Scale (EPDS) was used for depression screening for mothers, and the EPDS, Beck Depression Inventory (BDI) and General Health Questionnaire (GHQ) for fathers. A total of 75 mothers (47.5%) had EPDS scores > 12, and 45 fathers (48.9%) exceeded the threshold on one or more of the three screening instruments. Most of the variance in paternal and maternal depression was accounted for by neuroticism. However, while mothers appeared primarily influenced by their own personality, perinatal and infant-related factors, fathers appeared more influenced by mothers' personality difficulties and unresolved past events, and mothers' current mental health and infant-related problems, as well as the state of the marital/de facto relationship. The BDI and EPDS seemed to measure more severe pervasive forms of paternal depression than the GHQ, and the EPDS appeared to tap some items more specifically associated with perinatal psychological risk than the BDI. Depression in one partner was moderately correlated with depression in the other. High rates of paternal depression and anxiety in mothercraft settings suggest the need to routinely assess the mental state of both parents in these settings, and to include fathers in postnatal depression intervention programmes. The mother's negative perceptions of her infant's temperament are significantly associated with maternal and paternal depression, suggesting an important focus for intervention. 188 M. DUDLEY ET AL.

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The generation and evolution of defects in 4H–SiC p-n junctions due to carrier injection under forward bias have been investigated by synchrotron white beam x-ray topography, electroluminescence imaging, and KOH etching. The defects are Shockley stacking faults with rhombic or triangular shapes bound by partial dislocation loops with dislocation lines along Peierls valleys (〈11-20〉) or along the intersection of the basal plane containing the fault and diode surface. The Burgers vector of all bounding partials was of 1/3〈10-10〉-type. Among six possible types of partial dislocations with these properties, only two were observed in the volume of the epitaxial structure. One was tentatively identified as 30° carbon-core [C(g) 30°] and second as 30° silicon-core [Si(g) 30°] partial dislocation. Only one of them [proposed to be the Si(g) 30° partial] have been observed to move and emit light under forward bias. The other type of bounding dislocation [C(g) 30°] remained stationary during current injection. Low angle grain boundaries have been observed to act as one of a number of possible nucleation sites of stacking faults.

A kinematic (geometrical) diffraction simulation model has been developed to provide understanding of direct dislocation images on synchrotron white‐beam X‐ray topographs, and has been successfully applied to illustrate the contrast formation mechanisms involved in images of micropipe‐related superscrew dislocations in silicon carbide crystals. The coincidence of the simulations with the contrast features of the superscrew dislocation images, recorded using a series of synchrotron topography techniques, shows that this model is capable of revealing the detailed diffraction behavior of the highly distorted region around the dislocation core and determining the quantitative characteristics of the dislocations. The simulation technique is thus demonstrated to be a simple but efficient method for interpretation of synchrotron topographs, and may be applied to explain the topographic contrast characters of general crystal defects.