Yttria stabilized zirconia synthesis in supercritical CO2: Understanding of particle formation mechanisms in CO2/co-solvent systems

The increasing interest of supercritical (SC) fluids for inorganic materials synthesis recently stimulated the development of innovative synthesis processes and strategies. The supercritical CO₂ aided sol–gel process, developed for preparing various ceramic oxide powders with attractive applications in cosmetics, chromatography, catalysis or solid oxide fuel cells, usually suffer from both reproducibility problems and poor knowledge of the key parameters defining the final powder characteristics. In the present work a specific effort has been put on the understanding of reaction mechanisms and process parameters like co-solvent polarity and ageing time of the starting solution, which appeared to play a crucial role for the control of powder characteristics. Two different reaction mechanisms have been proposed to explain the formation of tetragonal yttria-doped zirconia powders by a batch process in either CO₂/pentane or CO₂/isopropanol mixtures. The first mechanism corresponds to a CO₂ anti-solvent precipitation process while the other one is based on a condensation reaction as in the conventional sol–gel process. This improved understanding in particle formation allows better control of powder characteristics and reproducibility.     

Intralenticular implant study in pigmented rabbits: opacity lensmeter assessment

PURPOSE: To quantitatively analyze the clarity of regenerated lens material after endocapsular lens extraction and restoration of the lens capsular bag with and without implantation of an intralenticular disc lens. SETTING: Shepherd Research Center, Allergan, Irvine, California, USA. METHOD: The clarity of regenerated lens material was evaluated by Interzeag Opacity Lensmeter 701 (OLM) recordings after endocapsular lens extraction in New Zealand/Dutch Belt pigmented rabbits with (n = 21) and without (n = 16) placement of a disc-shaped intralenticular implant in the capsular bag. Postoperative objective measurements were performed at 1, 2, and 3 weeks and 1, 2, 3, and 6 months. Comparisons were made between young and adult rabbits. RESULTS: Mean OLM results were similar in both groups at weeks 1, 2, 3, and 4. After 1 month, progressive central compaction of early irregular regenerated lens fibers was associated with increased OLM readings that were higher in the intralenticular implant group than in the control group. Regenerated lens opacification was greater in tissue posterior to the intralenticular lens than in that anterior to the disc lens. CONCLUSION: Insertion of an intralenticular disc lens into the lens capsule bag was associated with poor optical clarity primarily of the posterior regenerated lens tissue. The OLM was useful in assessing the degree of opacification of the regenerated lenses.     

Characterisation of 4043 aluminium alloy deposits obtained by wire and arc additive manufacturing using a Cold Metal Transfer process

ABSTRACT

4043 aluminium deposits were elaborated using a 3D print device equipped with a Cold Metal Transfer welding source. Two sets of process parameters leading to different average powers were compared in order to establish the relations between the powers and energies produced and the geometrical characteristics of the deposits. The effects of the travel speed and layer superposition on the transfer mechanisms as well as on the geometrical characteristics of the deposits were discussed for both sets of parameters. Finally, the formed microstructures were analysed and the porosity defects were quantified and discussed with regard to the heat input characteristics and the solidification conditions.     

Prevalence and predictors of posttraumatic stress in women undergoing an ovarian cancer investigation.

This study assessed posttraumatic stress disorder (PTSD) in women being investigated for an ovarian cancer diagnosis to determine prevalence and factors predicting PTSD in these patients. Participants (N = 75) were recruited from the Princess Margaret Hospital in Toronto, Ontario, after their initial clinic appointment and given a prediagnostic assessment that included measures of PTSD, depression, stress and pain. One month later, patients received an identical postdiagnostic assessment. No cases of clinical PTSD were detected, although 13.6% of participants were identified with subsyndromal PTSD. Multiple regression analyses showed that those participants reporting significant baseline depressive symptoms, definitively diagnosed with ovarian cancer, and with shorter treatment wait times were more likely to have a significant increase in PTSD symptoms. Supportive interventions aimed at reducing PTSD symptoms, launched prior to an ovarian cancer diagnosis, might optimally be directed at patients with baseline depressive symptoms and those with shorter treatment wait times. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hydroxytelechelic hydrocarbon copolymers with high aging resistance for elastomeric materials

Dihydroxytelechelic copolyalkenamers were prepared via metathetical polymerization of cyclic olefins (cyclooctadiene, cyclooctene and cyclododecene) in presence of first generation Grubbs catalyst and butene diacetate as functionalizing chain transfer agent in order to study their aging resistance. The influence of compositions and molar masses of the copolyalkenamers were investigated in terms of thermo‐mechanical properties. Increasing chains length or the proportion of polycyclooctadiene allow to get non‐cristalline polymers. Low T_g materials (between ?78°C and ?108°C) were prepared. The resistance towards oxidation of the different copolyalkenamers was carried out using a viscosity measurement method. A critical time, corresponding to a brutal increase of the apparent viscosity, was related to degradation of the polymers and was shown to be dependent on the Csp² proportion in the structure. The absence of vinylic units and the decrease of the double bonds content within the copolymers were proved to enhance the stability of the copolyalkenamers towards aging resistance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparing spiritual transformations and experiences of profound beauty.

Certain highly emotional experiences have the potential to produce long-lasting and meaningful changes in personality. Two such experiences are spiritual transformations and experiences of profound beauty. However, little is known about the cognitive appraisals or narrative elements involved in such experiences, how they are similar, and how they differ. In a study of emotion-related narratives, these experiences were found to share many features but also differ in their valence. Experiences of profound beauty are almost always positive, but spiritual transformations are both positive and negative. Moreover, spiritual transformations seem to produce long-lasting change, but experiences of profound beauty, although evocative, do not seem to produce long-lasting change. An emotion approach helps to elucidate two understudied but important emotional experiences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

AN ENERGY ANALYSIS OF BELT POLISHING PROCESS AND ITS APPLICATIONS TO TIME CYCLE AND TRACKING EFFECTS

Belt polishing is a fine machining process widely used to improve surface texture and to increase wear resistance and fatigue life. Despite the basics of this manufacturing process are not yet well understood, the cycle-time and the belt oscillations frequency are considered as fundamental process variables. In this article, their effects on the surface characterization and on the form aspects are investigated in connection with the principal physical mechanisms activated during the superfinishing operations (cutting, ploughing and sliding). With this aim, an energy approach of the belt polishing process, coupled with SEM observations of the abrasive belt, is introduced. Two belt polishing energetic regimes are identified and then discussed.     

Subjective Effects of Variable Delay and Speech Clipping in Dynamically Managed Voice Systems

The purpose of this paper is to examine speech impairments likely to arise in dynamically managed voice (DMV) systems. DMV systems utilize speech activity detection to exploit speech idle time and variable bit rate coding to exploit nonstationary speech statistics. The emphasis here is on systems using speech detection. This processing introduces two impairments not commonly found in traditional communication systems variable Speech burst delay and speech clipping. Simulations of these impairments were implemented, and formal subjective testing was performed to assess subjects' reactions to a range of impairment levels. Emphasis was on formal subjective listening tests and customer opinion of speech quality as defined by a rating scale. The test conditions are applicable to general telephony, where relatively high speech quality is required. Results on variable speech burst delay and front-end and midspeech burst clipping are presented. These results serve as input to the design process and to the establishment of performance guidelines for DMV systems.     

Controlled Distribution of Solid Catalysts into Two Immiscible Liquid Phases – Synthesis and Catalytic Applications

Photometathesis of C₃H₆ proceeded on the sprayed MoO₃ catalyst under UV irradiation with wavelength <290 nm. The photoactivity on the spray catalyst was 20-fold higher than that on the commercial MoO₃. The X-ray diffraction (XRD) results showed the anisotropic growth of the crystal in the spray catalyst. The edge-rich structure was formed in the bulk molybdenum oxide by spray reaction technique.