Modified CVD of nanoscale structures in and EVD of thin layers on porous ceramic membranes

Experiments on the modified chemical vapour deposition (CVD) and the electrochemical vapour deposition (EVD) of yttria-stabilized zirconia on porous substrates are reported. It is shown that, in the CVD stage, deposition occurs in a small (<20 um) region at the edge of the substrate, very likely leading to pore narrowing. This result illustrates the feasibility of the CVD technique for the modification of ceramic membranes to the (sub)nanometer scale. Film growth in the EVD stage is shown to be controlled by the inpore diffusion of the oxygen source reactant for short (<5 h) deposition times. The yttria to zirconia ratio in the deposited film is determined by the ratio present in the vapour phase. Very thin (<2 um) films can be deposited, which have a potential application in solid oxide fuel cells

On the kinetic study of electrochemical vapour deposition

A theoretical analysis is presented which quantitatively describes the transition behavior of the kinetics of the electrochemical vapour deposition of yttria-stabilized zirconia on porous substrates. It is shown that up to a certain deposition time and corresponding film thickness the rate limiting step is oxygen diffusion through the substrate pores, giving a linear dependence of the film thickness on the deposition time. For longer deposition times, i.e. thicker films, a transition of the rate limiting step to bulk electrochemical diffusion in the film occurs, resulting in a parabolic dependence of the film thickness on the deposition time. Simulation results are presented to show the effects of the experimental conditions on this transition time

Evaluation of porous ceramic cathode layers for solid oxide fuel cells

Sr0.15La0.85MnO3 layers with 2 and 10 u thickness, deposited on zirconia based electrolytes, were evaluated as cathodes for high temperature applications. Different electrode layers were characterized in terms of thickness, porosity, three phase boundary line per unit area (TPBL), and concentration polarization behavior. Electrodes with maximum porosity and TPBL exhibit minimum concentration polarization losses at constant current density

A Kinetic Study of the Electrochemical Vapor Deposition of Solid Oxide Electrolyte Films on Porous Substrates

The electrochemical vapor deposition (EVD) method is a very promising technique for making gas-tight dense solidelectrolyte films on porous substrates. In this paper, theoretical and experimental studies on the kinetics of the depositionof dense yttria-stabilized zirconia films on porous ceramic substrates by the EVD method are presented. The more systematictheoretical analysis is based on a model which takes into account pore diffusion, bulk electrochemical transport, andsurface charge-transfer reactions in the film growing process. The experimental work is focused on examining the effectsof the oxygen partial pressure and substrate pore dimension on the EVD film growth rates. In accordance with thetheoretical prediction, the pressure of oxygen source reactant (e.g., water vapor), the partial pressure of oxygen and substratepore dimension are very important in affecting the rate-limiting step and film growth rate of the EVD process. In thepresent experimental conditions (e.g., low pressure of oxygen source reactant and small substrate pore-size/thicknessratio), the diffusion of the oxygen source reactant in the substrate pore is found to be the rate-limiting step for the EVDprocess

Avoidance Learning as Predictor of Posttraumatic Stress in Firefighters

BACKGROUND: Avoidance is a well-established maintenance factor in anxiety-related psychopathology. Individuals prone to anxiety show more maladaptive avoidance responses in conditioning paradigms aimed at avoidance learning, which indicates impairments in safety learning. To what extent avoidance learning is associated with posttraumatic stress disorder (PTSD) is still unclear, despite the logical relevance to the symptomatology. In this prospective study, we investigate avoidance learning responses in first responders, a population at high risk for traumatic exposure and thus PTSD development, and studied whether avoidance learning was associated with concurrent and future PTSD symptoms. METHOD: Firefighters (N = 502) performed an avoidance learning task at baseline assessment in which they first learned that two conditioned stimuli (CS+) were followed by an aversive stimulus (US) and one conditioned stimulus (CS-) was not. After that, they could learn to which CS avoidance of the US was effective, ineffective or unnecessary. Self-reported PTSD symptoms were assessed at baseline, and at 6, 12, 18 and 24 months. RESULTS: Participants exhibited comparable avoidance patterns to low anxiety individuals from previous studies. Avoidance learning responses were not associated with PTSD symptoms at baseline nor at follow-up. DISCUSSION: Our study found no evidence that avoidance learning was related to PTSD symptom severity in a high-risk, yet low symptomatic population, nor did it predict the development of PTSD symptoms at a later point in time. Future research should focus on studying avoidance learning in a clinical or high symptomatic sample to further clarify the role of avoidance learning in PTSD development

Are there right hemisphere contributions to visually-guided movement? Manipulating left hand reaction time advantages in dextrals

This is the final version of the article. It first appeared from Frontiers Media via http://dx.doi.org/10.3389/fpsyg.2015.01203Many studies have argued for distinct but complementary contributions from each hemisphere in the control of movements to visual targets. Investigators have attempted to extend observations from patients with unilateral left- and right-hemisphere damage, to those using neurologically-intact participants, by assuming that each hand has privileged access to the contralateral hemisphere. Previous attempts to illustrate right hemispheric contributions to the control of aiming have focussed on increasing the spatial demands of an aiming task, to attenuate the typical right hand advantages, to try to enhance a left hand reaction time advantage in right-handed participants. These early attempts have not been successful. The present study circumnavigates some of the theoretical and methodological difficulties of some of the earlier experiments, by using three different tasks linked directly to specialized functions of the right hemisphere: bisecting, the gap effect, and visuospatial localization. None of these tasks were effective in reducing the magnitude of left hand reaction time advantages in right handers. Results are discussed in terms of alternatives to right hemispheric functional explanations of the effect, the one-dimensional nature of our target arrays, power and precision given the size of the left hand RT effect, and the utility of examining the proportions of participants who show these effects, rather than exclusive reliance on measures of central tendency and their associated null hypothesis significance tests.We are grateful to Lorna Jakobson, A. David Milner, Irene Logan, John Orphan, Phil Surette, and Jim Urqhuart for expert technical assistance. Leah T. Johnstone and two anonymous referees provided detailed comments on this manuscript. This research was supported by Medical Research Council of Canada Grant MA-7269 to MG and a Wellcome Trust Travel Grant to DC

Performances of Solid Oxide Cells with La0.97_{0.97}Ni0.5_{0.5}Co0.5_{0.5}O3−δ_{3-\delta} as Air-Electrodes

Based on previous studies of perovskites in the quasi-ternary system LaFeO$_{3}$–LaCoO$_{3}$–LaNiO$_{3}$, La$_{0.97}$Ni$_{0.5}$Co$_{0.5}$O$_{3}$ (LNC) is chosen as the most promising air-electrode material in the series for solid oxide cells (SOCs). The properties of the material itself have been investigated in detail. However, the evaluation of LNC97 air electrodes in practical SOCs is still at a very early stage. In the present study, SOCs were prepared based on LNC97 air electrodes. The I-U performance of the SOCs in both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes, i.e. reversible SOCs (r-SOCs), was investigated systematically for different air-electrode designs, temperatures and fuel gases. In general, the performance of the r-SOCs tested in the present study is higher than the published results of other LaFeO$_{3}$–LaCoO$_{3}$–LaNiO$_{3}$-based SOCs and is comparable to or even better than state-of-the-art La$_{1-x}$Sr$_{x}$Fe$_{1-y}$Co$_{y}$O$_{3}$ (LSCF)-based SOCs. Mid-term operation of about 1000 h for SOCs in both SOFC and SOEC modes primarily proved the stability of LNC97-based air electrodes. Impedance spectra were systematically applied to understand the polarization processes of the SOCs

Are there right hemisphere contributions to visually-guided movement? Manipulating left hand reaction time advantages in dextrals.

Many studies have argued for distinct but complementary contributions from each hemisphere in the control of movements to visual targets. Investigators have attempted to extend observations from patients with unilateral left- and right-hemisphere damage, to those using neurologically-intact participants, by assuming that each hand has privileged access to the contralateral hemisphere. Previous attempts to illustrate right hemispheric contributions to the control of aiming have focussed on increasing the spatial demands of an aiming task, to attenuate the typical right hand advantages, to try to enhance a left hand reaction time advantage in right-handed participants. These early attempts have not been successful. The present study circumnavigates some of the theoretical and methodological difficulties of some of the earlier experiments, by using three different tasks linked directly to specialized functions of the right hemisphere: bisecting, the gap effect, and visuospatial localization. None of these tasks were effective in reducing the magnitude of left hand reaction time advantages in right handers. Results are discussed in terms of alternatives to right hemispheric functional explanations of the effect, the one-dimensional nature of our target arrays, power and precision given the size of the left hand RT effect, and the utility of examining the proportions of participants who show these effects, rather than exclusive reliance on measures of central tendency and their associated null hypothesis significance tests