Surface modification of Scots pine: the effect of process parameters on the through thickness density profile

This study evaluated the significance of different process parameters (press temperature, closing time, holding time, moisture content and compression ratio) on solid wood surface densification and its effect on the density profile generated in Scots pine sapwood. Changes in the microstructure of the wood were also evaluated microscopically. The results showed that with a shorter closing time, densification occurred closer to the sample surface than with an extended closing time. At a compression temperature of 150 °C, the vertical density profile exhibited a sharp peak in density that was close to the wood surface. A higher temperature of 200 °C resulted in a slightly broader density peak that was less intense and further from the surface. A holding time of 10 min resulted in the wood compressing to a slightly greater extent than when using a holding time of 1 min. Higher moisture content led to more extensive deformation. The results indicate that surface modification by densification is a viable method of enhancing wood properties.     

Optical scattering of nanocrystalline Pb(ZrxTi1−x)O3 films

Optical characterization methods, like spectrophotometry at UV–vis-NIR wavelengths and prism-coupler method, were applied to polycrystalline Pb(Zr_xTi_1?x)O₃ thin films at various thicknesses. Thin films were deposited at room temperature by pulsed laser deposition on MgO (1 0 0) substrates and post-annealed at different temperatures. X-ray diffraction and atomic force microscopy were used to characterize the crystal structure and surface morphology of the thin films, respectively.Well oscillating transmission with a sharp fall near the absorption edge was found in films with high orientation and low surface roughness. Changes in the surface morphology and crystal orientation were found to modulate optical interference maxima and minima of the transmittance spectra and to increase the width of the TE₀ mode (Δβ ≈ 0.06) indicating an increase in the scattering losses of the films. Single-phase oriented films had sharpest coupling values (Δβ ≈ 0.005) of the TE₀ mode.     

Selection of input features across subjects for classifying crewmember workload using artificial neural networks

The issue of crewmember workload is important in complex system operation because operator overload leads to decreased mission effectiveness. Psychophysiological research on mental workload uses measures such as electroencephalogram (EEG), cardiac, eye-blink, and respiration measures to identify mental workload levels. This paper reports a research effort whose primary objective was to determine if one parsimonious set of salient psychophysiological features can be identified to accurately classify mental workload levels across multiple test subjects performing a multiple task battery. To accomplish this objective, a stepwise multivariate discriminant analysis heuristic and artificial neural network feature selection with a signal-to-noise ratio (SNR) are used. In general, EEG power in the 31-40-Hz frequency range and ocular input features appeared highly salient. The second objective was to assess the feasibility of a single model to classify mental workload across different subjects. A classification accuracy of 87% was obtained for seven independent validation subjects using neural network models trained with data from other subjects. This result provides initial evidence for the potential use of generalized classification models in multitask workload assessment.     

Clinic characteristics associated with reduced hospitalization of drug users with AIDS

The purpose of this study was to develop a substantive grounded theory of courage among middle-aged adults with long-term health concerns. Twenty-five persons from rural and non-metropolitan areas of Central Illinois were selected to participate in this study based on theoretical sampling procedures. Interviews of 1 to 2 hours using openended questions were audiotaped and transcribed verbatim. The data were analysed using grounded theory methods. Courage among middle-aged adults with long-term health concerns was determined to consist of an ongoing progressive-regressive process of becoming and being courageous. Being courageous involves being fully aware of and accepting the threat of a long-term health concern, solving problems using discernment, and developing enhanced sensitivities to personal needs and the world in general. Courageous behaviour consists of taking responsibility and being productive. Courage is not limitless, and the process of becoming and being courageous is dependent on intrapersonal and interpersonal factors. Health-care providers facilitate this process by demonstrating competence and communicating effectively. Outcomes of being courageous include personal integrity and thriving in the midst of normality.     

Identifying,framing and managing uncertainties in project portfolios

Uncertainties in the organization, external environment and from single projects may hamper project portfolio performance unless managed properly. This paper introduces a framework on uncertainties and their management in project portfolios and pursues increased understanding on how managers can take uncertainty into account better. We explore uncertainties, how managers frame them as opportunities or threats, and the actual practice of managing them across ten R&D project portfolios. The framework on project portfolio uncertainties and their management is further refined based on the empirical results. As key contributions, we show evidence on the balanced existence of three types of uncertainties, the threat bias in their framing, and the dominance of rational, opportunity driven mechanisms of control in uncertainty management. We discuss the context-dependent practice of project portfolio management and the need to complement rational mechanisms with structural and cultural, for project portfolio management to become a dynamic capability.     

Micromorphological studies of surface densified wood

Scots pine (Pinus sylvestris L.) wood was surface densified in its radial direction in an open press with one heated plate to obtain a higher density on the wood surface whilst retaining the overall thickness of the sample. This study investigated the effect of temperature (100, 150 and 200 °C) and press closing speed (5, 10 and 30 mm/min, giving closing times of 60, 30 and 10 s, respectively) on the micromorphology of the cell-wall, as well as changes occurring during set-recovery of the densified wood. The micromorphology was analysed using scanning electron microscopy (SEM) combined with a sample preparation technique based on ultraviolet-excimer laser ablation. Furthermore, the density profiles of the samples were measured. Low press temperature (100 °C) and short closing time (10 s) resulted in more deformation through the whole thickness, whilst increasing the temperature (150 and 200 °C) and prolonging the closing time (30 and 60 s) enabled more targeted deformation closer to the heated plate. The deformation occurred in the earlywood regions as curling and twisting of the radial cell-walls, however, no apparent cell-wall disruption or internal fracture was observed, even at low temperatures and fast press closing speed, nor after soaking and drying of the samples. In the SEM-analysis after soaking and drying, it was noticed that the cells did not completely recover their original form. Thus, part of the deformation was considered permanent perhaps due to viscoelastic flow and plastic deformation of the cell-wall components.     

Extrusion of YAG Tubes Shows that Bottom‐up Processing is Not Always Optimal

Liquid‐feed flame spray pyrolysis provides easily dispersed, unaggregated nanopowders with average particle sizes of 20–70 nm depending on the processing conditions. Their chemical compositions can be controlled to ppm levels via control of the initial precursor solution. In this paper, Y₃Al₅O₁₂ composition nanopowders are produced that are atomically mixed but offer a hexagonal crystal structure rather than a YAG structure. Y₂O₃ and δ‐Al₂O₃ nanopowders are also produced and mixed to evaluate reactive sintering. It is shown that nanopowder/polymer mixtures permit the extrusion of tubes that retain their shape on debindering and sintering to ≥95% theoretical density. More importantly, the sintering behavior of hex‐Y₃Al₅O₁₂ is compared with that of tubes formed using 3:5 Y₂O₃:δ‐Al₂O₃ mixtures to test the so‐called bottom‐up paradigm, which suggests that mixing on the finest length scales should provide optimal control of sintering rates, final densities, and grain sizes. Instead, it is found that reactive sintering is faster and offers better control of final grain sizes. Dense sintered tubes are translucent, and dimensional uniformity is maintained from extrusion through sintering.     

Determination of the IgA 7 S/IgA 11 S ratio in human bronchial secretion by thin layer gel filtration immunoelectrophoresis (author's transl)

After extraction by treatment with Ecteola-cellulose, IgA 11 S and IgA 7 S from human bronchial secretion were first separated by thin-layer gel filtration in Ultrogel AcA 3-4, and then were analyzed by crossed immunoelectrophoresis with an immune serum against alpha chain. Precipitation areas were measured separately. A correlation factor was necessary to express IgA 7 S in terms of IgA 11 S: it was calculated with standard curves made with serum and colostral IgA.