Effects of linear versus sigmoid coding of visual or audio biofeedback for the control of upright stance.

Although both visual and audio biofeedback (BF) systems for postural control can reduce sway during stance, a direct comparison between the two systems has never been done. Further, comparing different coding designs of audio and visual BF may help in elucidating how BF information is integrated in the control of posture, and may improve knowledge for the design of innovative BF systems for postural control. The purpose of this paper is to compare the effects of linear versus sigmoid coding of trunk acceleration for audio and visual BF on postural sway in a group of eight, healthy subjects while standing on a foam surface. Results showed that sigmoid-coded audio BF reduced sway acceleration more than did a linear-coded audio BF, whereas a linear-coded visual BF reduced sway acceleration more than a sigmoid-coded visual BF. In addition, audio BF had larger effects on reducing center of pressure (COP) displacement whereas visual BF had larger effects on reducing trunk sway. These results suggest that audio and visual BF for postural control benefit from different types of sensory coding and each type of BF may encourage a different type of postural sway strategy.     

The design of chiral separation media using monodisperse functionalized macroporous beads: effects of polymer matrix, tether, and linkage chemistry

Porous size monodisperse methacrylate beads containing amino and hydroxyl groups, which can be used as a platform for the production of chiral separation media, have been prepared using the staged templated suspension polymerization process. The monomers 2-hydroxyethyl methacrylate and several tert-butoxycarbonyl-protected aminoalkyl methacrylates were used for the preparation of both hydroxyl- and amino-functionalized beads. Attachment of a chiral selector based on L-valine-3,5-dimethylanilide through a carbamate and a urea linkage, respectively, provides chiral stationary phases with excellent enantioselectivities in the separation of the enantiomers of 3,5-dinitrobenzamido derivatives of alpha-amino acids. For comparison purposes, a separation medium was also prepared by the direct polymerization of a chiral monomer analogous to the hydroxyethyl methacrylate-based stationary phase. The chiral stationary phases prepared with the N-methyl-2-aminoethyl methacrylate platform exhibit the best selectivity, and separation factors as high as 15 were achieved under normal-phase HPLC conditions.     

Language production and serial order: A functional analysis and a model.

In speech production, previously spoken and upcoming words can impinge on the word currently being said, resulting in perseverations (e.g., "beef needle soup") and anticipations (e.g., "cuff of coffee"). These errors reveal the extent to which the language-production system is focused on the past, the present, and the future and therefore are informative about how the system deals with serial order. This article offers a functional analysis of serial order in language and develops a general formal model. The centerpiece of the model is a prediction that the fraction of serial-order errors that are anticipatory, as opposed to perseveratory, can be closely predicted by overall error rate. The lower the error rate, the more anticipatory the errors are, regardless of the factors influencing error rate. The model is successfully applied to experimental and natural error data dealing with the effects of practice, speech rate, individual differences, age, and brain damage. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Local Flow Behavior of Ceramic Slurries in Tape Casting, as Investigated by Laser–Doppler Velocimetry

The local flow behavior in a tape-casting unit for processing ceramic slurries was investigated by laser–Doppler velocimetry (LDV). The most remarkable feature of the LDV system used was its high spatial resolution (24 μm) and temporal resolution (5 μs). A translucent Newtonian model fluid which, in the relevant processing window, at higher shear rates, exhibits a rheological behavior similar to that of a typical ceramic slurry, was chosen to determine the velocity distribution in the flow channel (i.e., in the tape-casting unit). The flow behavior was measured directly in several particular regions of the flow channel, which substantially consisted of a double doctor-blade assembly. The velocity distribution obtained below the forming doctor blade showed the strong influence of the casting speed on the flow behavior of the model fluid. Furthermore, the measured flow behavior was analyzed, based on the assumptions of fluid dynamics. Below the doctor blade, the flow behavior was considered to be a combination of pressure flow and drag (Couette) flow. The flow rates from the applied hydrostatic pressure and external drag forces were shown to be additive. A comparison between the measured velocity profiles and the model calculations showed excellent agreement. A flow reversal (secondary flow), never before measured quantitatively, was detected between the two inserted rectangular blades. Apparently, secondary flows influenced the surface properties of the cast green tapes.     

Experimental and computational study of morphological and electrical properties of tin/plasma polymer nanocomposites

Composite tin/n-hexane plasma polymer films were prepared by means of RF magnetron sputtering of tin target in Ar:n-hexane mixture and characterised by various analytical techniques. Their chemical composition was examined by XPS, current-voltage characteristics were measured, and their structure was investigated by conventional TEM and electron tomography. The acquired three-dimensional reconstructions were morphologically analysed by a self-made computer analytical tool, which estimated the mean form factor and the average effective radius of the reconstructed metal inclusions.     

Evolution of physical properties of amorphous Fe–Ni–Nb–B alloys with different Ni/Fe ratio upon thermal treatment

Amorphous ribbons (Fe–Ni)₈₁Nb₇B₁₂ with Ni/Fe = 0, 1/6, 1/3 and 1 were prepared by planar flow casting. Thermal treatment of samples was performed in vacuum at temperatures chosen to map the evolution of selected properties in the course of transformation from amorphous state. The coefficient of thermal dilatation exhibits changes at temperatures close to the glass transition, Curie and crystallization temperatures; these effects are enhanced or suppressed by cyclic thermal treatments up to the vicinity of these temperatures. The values of saturation magnetostriction λ_S allow to infer about processes taking place in the investigated materials, especially with respect to formation of new magnetic phases or magnetic anisotropy.Complex processes of structural transformations induced by thermal treatment are strongly affected by Ni percentage. A transitional, magnetically harder phase, which is formed at lower temperatures preferentially near surfaces of the Ni-richest alloy, produces characteristic hysteresis loop shape. This shape disappears after annealing at higher temperatures and enables the material to show the lowest coercivity of the whole alloy series. The saturation magnetic polarization reflects mainly the resulting Curie temperature, which falls with increasing Ni percentage. Magnetic hysteresis loops were also used in the study of dynamics of magnetic domains by MOKE. Domain shape evolution is shown in dependence on composition and thermal treatment as well as a function of applied magnetic field, ranging from remanent sample state to magnetic saturation.     

Translation of segment scale stiffening into macroscale reinforcement in polymer nanocomposites

Structuring of polymer nanocomposites (PNCs) with an aid of relatively weak external magnetic fields has been studied as a method for control of the nano- and microstructure. Magnetic nanoparticles (NPs) were assembled into high aspect ratio one-dimensional strings and unidirectionally oriented with the magnetic field (B = 0–50 mT) within the photopolymer matrix. The effect of the anisotropic MNPs assemblies on the mechanical properties was studied over a wide temperature range for the first time. The impact of various reinforcing mechanisms was distinguished with respect to the position of the glass transition temperature (T_g). The reinforcing effect exhibits temperature dependency with a maximum ~65°C above the glass transition and only negligible effect below the T_g. In addition, significant directional anisotropy of stiffness was observed. Composite micromechanics was applied to interpret the orientation and size-dependent reinforcement of PNCs, and temperature-dependent stiffness of the polymer-MNP structures was quantified. The presence of polymer chains with altered dynamics surrounding the MNPs inside the anisotropic assemblies was proposed to be an essential nanoscale mechanism mediating the stress transfer and contributing to mechanical robustness of the hybrid structures and PNCs. POLYM. ENG. SCI., 60:587–596, 2020. © 2019 Society of Plastics Engineers     

Failure analysis of thermally cycled columnar thermal barrier coatings produced by high-velocity-air fuel and axial-suspension-plasma spraying: A design perspective

Axial-suspension-plasma spraying (ASPS) is a fairly recent thermal spray technology which enables production of ceramic top coats in TBCs, incorporating simultaneously the properties of both the conventional-plasma sprayed (highly insulating porous structures) and electron-beam-physical-vapor-deposited (strain-tolerant columnar structures) top coats. TBCs are required to insulate the hot components in a gas turbine engine against high temperature and harsh operating conditions. Periodic heating and cooling of turbine engines during operation can create severe thermal cyclic fatigue conditions which can degrade the performance of these coatings eventually leading to the failure. An in-depth experimental investigation was performed to understand the failure behavior of columnar TBCs subjected to thermal cyclic fatigue (TCF) test at 1100?C. The study revealed that the TCF performance was influenced to an extent, by the top coat microstructure, but was primarily affected by the severity of thermally grown oxide (TGO) growth at the bond coat-top coat interface. Mixed failure modes comprising crack propagation through the bond coat-TGO interface, through TGO and within the top coat were identified. Based on the analysis of the experimental results and thorough discussion a novel design of microstructure for the high TCF performance columnar TBC is proposed.     

Revisiting Steroidogenic Pathways in the Human Placenta and Primary Human Trophoblast Cells

Steroid hormones play a crucial role in supporting a successful pregnancy and ensuring proper fetal development. The placenta is one of the principal tissues in steroid production and metabolism, expressing a vast range of steroidogenic enzymes. Nevertheless, a comprehensive characterization of steroidogenic pathways in the human placenta and potential developmental changes occurring during gestation are poorly understood. Furthermore, the specific contribution of trophoblast cells in steroid release is largely unknown. Thus, this study aimed to (i) identify gestational age-dependent changes in the gene expression of key steroidogenic enzymes and (ii) explore the role of trophoblast cells in steroid biosynthesis and metabolism. Quantitative and Droplet Digital PCR analysis of 12 selected enzymes was carried out in the first trimester (n = 13) and term (n = 20) human placentas. Primary trophoblast cells (n = 5) isolated from human term placentas and choriocarcinoma-derived cell lines (BeWo, BeWo b30 clone, and JEG-3) were further screened for gene expression of enzymes involved in placental synthesis/metabolism of steroids. Finally, de novo steroid synthesis by primary human trophoblasts was evaluated, highlighting the functional activity of steroidogenic enzymes in these cells. Collectively, we provide insights into the expression patterns of steroidogenic enzymes as a function of gestational age and delineate the cellular origin of steroidogenesis in the human placenta.