SDC-SCFZ dual-phase ceramics: Structure,electrical conductivity,thermal expansion,and O2 permeability

New CO₂-resistant dual-phase Sm_0.2Ce_0.8O_1.925–SrCo_0.4Fe_0.55Zr_0.05O_3-δ (SDC-SCFZ) ceramics present a promising outlook for potential future applications in membrane reactors and solid oxide fuel cells. Their high oxygen permeation flux and stability in CO₂ sweep gas also allow their integration in oxyfuel combustion. Here the structural characteristics, electrical conductivities, thermal expansion behaviors, and oxygen permeabilities of four different SDC-SCFZ membranes with weight ratios of 10:90, 25:75, 50:50, and 75:25 (SDC:SCFZ) are systematically studied. Among these four SDC-SCFZ compositions, 0.6 mm-thick 25 wt% SDC-75 wt% SCFZ displayed the highest oxygen permeation fluxes that reach 1.26 mL min⁻¹ cm⁻² at 950°C and retained its phase integrity under alternating He and CO₂ sweep gas over 72 hours of operation. This composite also showed a moderate thermal expansion coefficient of 1.90 × 10⁻⁵ K⁻¹ between 30°C and 1000°C and an electrical conductivity of at least 16 S cm⁻¹ at 550°C and above. Modeling studies revealed that the oxygen permeation fluxes through 25SDC-75SCFZ are limited by surface exchange reactions from 700°C to 800°C and mixed bulk diffusion and surface exchange reactions above 800°C.     

A superhydrophilic titanium implant functionalized by ozone gas modulates bone marrow cell and macrophage responses

Bone-forming cells and M? play key roles in bone tissue repair. In this study, we prepared a superhydrophilic titanium implant functionalized by ozone gas to modulate osteoconductivity and inhibit inflammatory response towards titanium implants. After 24 h of ozone gas treatment, the water contact angle of the titanium surface became zero. XPS analysis revealed that hydroxyl groups were greatly increased, but carbon contaminants were largely decreased 24 h after ozone gas functionalization. Also, ozone gas functionalization did not alter titanium surface topography. Superhydrophilic titanium (O₃–Ti) largely increased the aspect ratio, size and perimeter of cells when compared with untreated titanium (unTi). In addition, O₃–Ti facilitated rat bone marrow derived MSCs differentiation and mineralization evidenced by greater ALP activity and bone-like nodule formation. Interestingly, O₃–Ti did not affect RAW264.7 M? proliferation. However, naive RAW264.7 M? cultured on unTi produced a two-fold larger amount of TNFα than that on O₃–Ti. Furthermore, O₃–Ti greatly mitigated proinflammatory cytokine production, including TNFα and IL-6 from LSP-stimulated RAW264.7 M?. These results demonstrated that a superhydrophilic titanium prepared by simple ozone gas functionalization successfully increased MSCs proliferation and differentiation, and mitigated proinflammatory cytokine production from both naive and LPS-stimulated M?. This superhydrophilic surface would be useful as an endosseous implantable biomaterials and as a biomaterial for implantation into other tissues.     

Multiple spatial sounds in hierarchical menu navigation for visually impaired computer users

This paper describes a user study on the benefits and drawbacks of simultaneous spatial sounds in auditory interfaces for visually impaired and blind computer users. Two different auditory interfaces in spatial and non-spatial condition were proposed to represent the hierarchical menu structure of a simple word processing application. In the horizontal interface, the sound sources or the menu items were located in the horizontal plane on a virtual ring surrounding the user’s head, while the sound sources in the vertical interface were aligned one above the other in front of the user. In the vertical interface, the central pitch of the sound sources at different elevations was changed in order to improve the otherwise relatively low localization performance in the vertical dimension. The interaction with the interfaces was based on a standard computer keyboard for input and a pair of studio headphones for output. Twelve blind or visually impaired test subjects were asked to perform ten different word processing tasks within four experiment conditions. Task completion times, navigation performance, overall satisfaction and cognitive workload were evaluated. The initial hypothesis, i.e. that the spatial auditory interfaces with multiple simultaneous sounds should prove to be faster and more efficient than non-spatial ones, was not confirmed. On the contrary—spatial auditory interfaces proved to be significantly slower due to the high cognitive workload and temporal demand. The majority of users did in fact finish tasks with less navigation and key pressing; however, they required much more time. They reported the spatial auditory interfaces to be hard to use for a longer period of time due to the high temporal and mental demand, especially with regards to the comprehension of multiple simultaneous sounds. The comparison between the horizontal and vertical interface showed no significant differences between the two. It is important to point out that all participants were novice users of the system; therefore it is possible that the overall performance could change with a more extensive use of the interfaces and an increased number of trials or experiments sets. Our interviews with visually impaired and blind computer users showed that they are used to sharing their auditory channel in order to perform multiple simultaneous tasks such as listening to the radio, talking to somebody, using the computer, etc. As the perception of multiple simultaneous sounds requires the entire capacity of the auditory channel and total concentration of the listener, it does therefore not enable such multitasking.     

Multi-scale computational model for failure analysis of metal frames that includes softening and local buckling

In this work we present a new modelling paradigm for computing the complete failure of metal frames by combining the stress-resultant beam model and the shell model. The shell model is used to compute the material parameters that are needed by an inelastic stress-resultant beam model; therefore, we consider the shell model as the meso-scale model and the beam model as the macro-scale model. The shell model takes into account elastoplasticity with strain-hardening and strain-softening, as well as geometrical nonlinearity (including local buckling of a part of a beam). By using results of the shell model, the stress-resultant inelastic beam model is derived that takes into account elastoplasticity with hardening, as well as softening effects (of material and geometric type). The beam softening effects are numerically modelled in a localized failure point by using beam finite element with embedded discontinuity. The original feature of the proposed multi-scale (i.e. shell-beam) computational model is its ability to incorporate both material and geometrical instability contributions into the stress-resultant beam model softening response. Several representative numerical simulations are presented to illustrate a very satisfying performance of the proposed approach.     

A system for efficient motor learning using multimodal augmented feedback

Numerous studies have established that using various forms of augmented feedback improves human motor learning. In this paper, we present a system that enables real-time analysis of motion patterns and provides users with objective information on their performance of an executed set of motions. This information can be used to identify individual segments of improper motion early in the learning process, thus preventing improperly learned motion patterns that can be difficult to correct once fully learned. The primary purpose of the proposed system is to serve as a general tool in the research on impact of different feedback modalities on the process of motor learning, for example, in sports or rehabilitation. The key advantages of the system are high-speed and high-accuracy tracking, as well as its flexibility, as it supports various types of feedback (auditory and visual, concurrent or terminal). The practical application of the proposed system is demonstrated through the example of learning a golf swing.     

Enhanced oxygen permeation through perovskite hollow fibre membranes by methane activation

Hollow fibre membranes of mixed conducting perovskite La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) were prepared via the combined phase inversion and sintering technique. The fibres were tested for air separation with a home-made reactor under the oxygen partial pressure gradient generated by the air/He streams. Some fibres were in situ activated by introducing methane in the He sweeping gas at high temperatures. The activated membranes with new morphology were created by transforming the inner densified surface layer to a porous structure. Compared to the original membranes, the activated gave appreciable higher oxygen fluxes. At 800 °C, the oxygen fluxes were increased by a factor of 10 after activation was carried out at 1000 °C for 1 h.     

Construction of Cu7S4@CuCo2O4 Yolk–Shell Microspheres Composite and Elucidation of Its Enhanced Photocatalytic Activity,Mechanism, and Pathway for Carbamazepine Degradation

Water pollution caused by the massive use of medicines has caused significant environmental problems. This work first reports the synthesis and characterization of the Cu₇S₄/CuCo₂O₄ (CS/CCO) yolk–shell microspheres via hydrothermal and annealing methods, and then investigates their photocatalytic performance in removing organic water pollutants. The 10-CS/CCO composite with yolk–shell microspheres exhibits the highest photodegradation rate of carbamazepine (CBZ), reaching 96.3% within 2 h. The 10-CS/CCO also demonstrates more than two times higher photodegradation rates than the pure (Cu₇S₄) CS and (CuCo₂O₄) CCO. This outstanding photocatalytic performance can be attributed to the unique yolk–shell structure and the Z-scheme charge transfer pathway, reducing multiple reflections of the acting light. These factors enhance the light absorption efficiency and efficiently transfer photoexcited charge carriers. In-depth, photocatalytic degradation pathways of CBZ are systematically evaluated via the identification of degradation intermediates with Fukui index calculation. The insights gained from this work can serve as a guideline for developing low-cost and efficient Z-scheme photocatalyst composites with the yolk–shell structure.     

Modeling study of oxygen permeation through an electronically short‐circuited YSZ‐based asymmetric hollow fiber membrane

Here, oxygen fluxes through an electronically short‐circuited asymmetric Ag‐YSZ|YSZ|LSM‐YSZ hollow fiber prepared via a combined spinning and sintering route were tested and correlated to an explicit oxygen permeation model. The average oxygen permeation through such asymmetric hollow fiber with a 27 μm‐thick YSZ dense layer reached 0.52 mL (STP) cm^?2 min^?1 at 1173 K. From the model results, we can obtain the characteristic thickness, the effects of the temperature, and the effect of He sweep gas flow rate to the individual step contribution. The oxygen partial pressure variation in the permeate side, the local oxygen flux, and the three‐different resistance distribution along the axial direction of the asymmetric hollow fiber are theoretically studied; providing guidelines to further improve the membrane performance for oxygen separation. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3491–3500, 2017