Simon effect with and without awareness of the accessory stimulus.

The authors investigated whether a Simon effect could be observed in an accessory-stimulus Simon task when participants were unaware of the task-irrelevant accessory cue. In Experiment 1A a central visual target was accompanied by a suprathreshold visual lateral cue. A regular Simon effect (i.e., faster cue-response corresponding reaction times [RTs]) was found. Experiment 1B demonstrated that this effect cannot be attributed to perceptual grouping of the target and cue. Experiments 2A, 2B, and 2C showed a reverse Simon effect (i.e., faster noncorresponding RTs) when participants were not aware of the cue. In this condition, the Simon effect would occur relative to the reorientation of attention from the cue, which would initially capture attention, toward the target. This conclusion is supported by the results of Experiments 3A and 3B, in which the reorientation of attention was induced by having the target flash after its onset. With suprathreshold cues either a reverse or regular Simon effect was observed by using a 100-ms or ≥200-ms onset flashing interval, respectively, whereas with subthreshold cues a reverse Simon effect was found irrespective of the interval length. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Highly efficient enzyme-functionalized porous zirconia microtubes for bacteria filtration

In contrast to polymer membranes, ceramic membranes offer considerable advantages for safe drinking water provision due to their excellent chemical, thermal, and mechanical endurance. In this study, porous ceramic microtubes made of yttria stabilized zirconia (YSZ) are presented, which are conditioned for bacteria filtration by immobilizing lysozyme as an antibacterial enzyme. In accordance with determined membrane pore sizes of the nonfunctionalized microtube of ≤200 nm, log reduction values (LRV) of nearly 3 (i.e., bacterial retention of 99.9%) were obtained for bacterial retention studies using gram-positive model bacterium Micrococcus luteus. Immobilization studies of lysozyme on the membrane surface reveal an up to six times higher lysozyme loading for the covalent immobilization route as compared to unspecific immobilization. Antibacterial activity of lysozyme-functionalized microtubes was assessed by qualitative agar plate test using Micrococcus luteus as substrate showing that both the unspecific and the covalent lysozyme immobilization enhance the microtubes' antibacterial properties. Quantification of the enzyme activity at flow conditions by photometric assays reveals that the enzyme activities of lysozyme-functionalized microtubes depend strongly on applied flow rates. Intracapillary feeding of bacteria solution and higher flow rates lead to reduced enzyme activities. In consideration of different applied flow rates in the range of 0.2-0.5 mL/min, the total lysozyme activity increases by a factor of 2 for the covalent immobilization route as compared to the unspecific binding. Lysozyme leaching experiments at flow conditions for 1 h show a significant higher amount of washed-out lysozyme (factor 1.7-3.4) for the unspecific immobilization route when compared to the covalent route where the initial level of antibacterial effectiveness could be achieved by reimmobilization with lysozyme. The presented platform is highly promising for sustainable bacteria filtration.     

Micromachining of ceramic surfaces: Hydroxyapatite and zirconia

Computerised Numerical Control (CNC) precision machining can be employed as a fast and reproducible method for surface micropatterning. For biomedical applications an efficient and reproducible micropatterning of zirconia and calcium phosphate based materials is highly sought in order to guide implant interactions with surrounding biological tissues for a better osseointegration. Therefore, CNC precision machining of zirconia and hydroxyapatite substrates is investigated in this study and optimised process parameters are reported. By microgrinding and micromilling microgrooves with a minimum width of 100 μm were obtained and process parameters such as cutting tool diameter and feed velocity discussed. As all samples were sintered prior to the micropatterning process, the influence of sintering temperature on the pattern quality, size and hardness of the obtained samples are studied. Vickers hardness of the different sintered ceramic surfaces was measured to correlate the possible wear impact on the tip of the cutting tools. The stiffness and the hardness of the used cutting tools were measured and their effect on the cutting results was discussed. The pattern quality and the average roughness in the machined microgrooves were analysed by 3D-profilometry and imaged by SEM. Comparison of the two machining techniques yielded more defined and less fractured micropatterns for microgrinding. The process efficiency for both methods was limited by the economic life time of the tool tips. For CNC grinding the life time was downsized due to more pronounced abrasive wear. For both materials the hardness was the crucial process parameter, which was adjusted by the sintering temperature. For milling of zirconia the sintering should not exceed a temperature of 1100 °C to minimize tool wear. A temperature of lower 1200 °C is suggested for the milling of HA. For sintering temperatures higher than 1200 °C the machining of both ceramic surfaces was hardly possible. The feed velocity was found not having a significant influence on the obtained micropattern width. The preset line pitch of 100 μm was excellently reached for both applied machining processes. It was found that lower feed velocities and smaller tool diameters caused deeper micropatterns.     

Gel Casting of Free‐Shapeable Ceramic Membranes with Adjustable Pore Size for Ultra‐ and Microfiltration

The growing demand of reliable high‐performance membrane materials for separation processes requires new simple, straightforward, environmental friendly, sustainable approaches for membrane fabrication. In this study, we present an environmentally friendly gel‐casting, one‐pot process based on ionotropic‐gelation for obtaining alumina membranes. A slurry of alumina particles and the biopolymer alginate, which acts in combination with calcium iodate like a resin, was gelled in a controllable temperature dependent manner. Alumina membranes are obtained by three different shaping routes (extrusion, free‐forming, casting). The suitability of extruded capillaries in a polymer‐ceramic hybrid state (green body) and after sintering (1150°C for 2 h) for potential application in micro‐ and ultrafiltration is evaluated by monitoring the chemical and mechanical stability, permeability and separation behavior. Varying the initial alumina particle size from 200 to 900 nm, membranes with a narrow pore size distribution, predictable and tunable average pore diameters from 70 up to 480 nm and a constant open porosity of ~40%, are obtained. The permeability behavior is tested with fluorescence labeled submicron‐ and nano‐particles. Our novel colloidal processing route represents a very versatile tool for designing and manufacturing ceramic membranes with complex shapes for micro‐ (>0.1 μm) and ultrafiltration (0.1–0.01 μm).     

Probiotics Affect One‐Carbon Metabolites and Catecholamines in a Genetic Rat Model of Depression

1 Scope

Probiotics may influence one‐carbon (C1) metabolism, neurotransmitters, liver function markers, or behavior.

2 Methods and results

Male adult Flinders Sensitive Line rats (model of depression, FSL; n = 22) received Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 (10⁹ or 10¹⁰ colony‐forming units per day) or vehicle for 10 weeks. The controls, Flinders Resistant Line rats (FRL, n = 8), only received vehicle. C1‐related metabolites were measured in plasma, urine, and different tissues. Monoamine concentrations were measured in plasma, hippocampus, and prefrontal cortex. Vehicle‐treated FSL rats had higher plasma concentrations of betaine, choline, and dimethylglycine, but lower plasma homocysteine and liver S‐adenosylmethionine (SAM) than FRLs. FSL rats receiving high‐dose probiotics had lower plasma betaine and higher liver SAM compared to vehicle‐treated FSL rats. FSLs had higher concentrations of norepinephrine, dopamine, and serotonin than FRLs across various brain regions. Probiotics decreased plasma dopamine in FSLs in a dose‐dependent manner. There were no detectable changes in liver function markers or behavior.

3 Conclusions

Probiotics reduced the flow of methyl groups via betaine, increased liver SAM, and decreased plasma dopamine and norepinephrine. Since these changes in methylation and catecholamine pathways are known to be involved in several diseases, future investigation of the effect of probiotics is warranted.     

The nacre protein perlucin nucleates growth of calcium carbonate crystals

Atomic force microscopy (AFM) in aqueous solution was used to investigate native nacre of the marine snail Haliotis laevigata on the microscopic scale and the interaction of purified nacre proteins with calcium carbonate crystals on the nanoscopic scale. These investigations were controlled by scanning electron microscopy (SEM), light microscopy (LM) and biochemical methods. For investigations with AFM and SEM, nacre was cleaved parallel to the aragonite tablets in this biogenic polymer/mineral composite. Multilamellar organic sheets consisting of a core of chitin with layers of proteins attached on both sides lay between the aragonite layers consisting of confluent aragonite tablets. Cleavage appeared to occur between the aragonite tablet layer and the protein layer. AFM images revealed a honeycomb‐like structure to the organic material with a diameter of the ‘honeycombs’ equalling that of the aragonite tablets. The walls of the structures consisted of filaments, which were suggested to be collagen. The flat regions of the honeycomb‐like structures exhibited a hole with a diameter of more than 100 nm. When incubated in saturated calcium carbonate solution, aragonite needles with perfect vertical orientation grew on the proteinacous surface. After treatment with proteinase K, no growth of orientated aragonite needles was detected. Direct AFM measurements on dissolving and growing calcite crystals revealed a surface structure with straight steps the number of which decreased with crystal growth. When the purified nacre protein perlucin was added to the growth solution (a super‐saturated calcium carbonate solution) new layers were nucleated and the number of steps increased. Anion exchange chromatography of the water‐soluble proteins revealed a mixture of about 10 different proteins. When this mixture was dialysed against saturated calcium carbonate solution and sodium chloride, calcium carbonate crystals precipitated together with perlucin leaving the other proteins in the supernatant. Thus perlucin was shown to be a protein able to nucleate calcium carbonate layers on calcite surfaces, and in the presence of sodium chloride, is incorporated as an intracrystalline protein into calcium carbonate crystals.     

Influence on Simon and SNARC effects of a nonspatial stimulus-response mapping: Between-task logical recoding.

In 4 experiments, we intermixed trials in which the stimulus color was relevant with trials where participants had to judge the stimulus shape or parity and found that the logical-recoding rule (Hedge & Marsh, 1975) applied to the relevant dimension in a task can generalize to the irrelevant dimension of the other task. The mapping assigned to participants in color-relevant trials modulated the Simon and SNARC (spatial-numerical association of response codes) effects (Simon & Small, 1969; Dehaene, Bossini, & Giraux, 1993) observed in shape- and parity-relevant trials. Standard effects were obtained when color-relevant trials required participants to respond by pressing a key of the same color as the stimulus, whereas an alternate-color mapping caused either the disappearance or reversal of the effects. The present results demonstrate that for between-task transfer effects to occur the critical dimensions in the two alternative tasks do not have to share the same representation nor need the stimuli of the two tasks have any feature in common. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of micropatterning methods for ceramic surfaces

The fabrication of defined ceramic micropatterns smaller than 100 μm is due to the hardness and brittleness of ceramic materials still very challenging. However, in recent years, micropatterned ceramic surfaces have become highly interesting for biomedical applications or the fabrication of energy converting devices, such as solid oxide fuel or solar cells. In this study we evaluate six modern techniques for ceramic pattern fabrication with feature sizes ranging from 5 to 100 μm. Ceramic materials such as alumina, zirconia, silica and hydroxyapatite are discussed. Advantages and disadvantages for each process are highlighted and compared to the other techniques. Three of these techniques, namely microtransfer molding, modified micromolding and Aerosol-Jet^® printing generate patterns starting with aqueous ceramic suspensions. The other three techniques, micromachining and two different types of laser treatment produce micropatterns by material removal from solid ceramic substrates. The detailed analysis yields that properties such as the desired micropatterning size, shape or the production time are strongly dependant on the chosen technique.     

Micromolding of Calcium Carbonate Using a Bio‐Inspired,Coacervation‐Mediated Process

Based on a novel approach that takes into account the coacervation of calcium and poly(acrylic acid) (PAA), we were able to biomimetically produce molded micropatterned parts from amorphous calcium carbonate (ACC) particles. We studied the time‐ and concentration‐dependent growth of Ca²⁺/PAA coacervate droplets using dynamic light scattering (DLS) and turbidity measurements. Applying these results for the generation of high amounts of unstable ACC particles, we were able to produce slurries that could be molded into micropatterned casts. The obtained slurries contained both micrometer sized ACC particles and smaller nano‐sized particles. When both types of particles were used for molding, materials with a high surface roughness could be produced, while the micropatterns of the molds could not be reproduced properly. However, by removing the bigger particles from the slurry using only the smaller, unstable, ACC particles, good reproduction of the micropatterns could be achieved, yielding smooth surfaces with a high surface area. The processing route represents a versatile platform for the bottom‐up preparation of micropatterned ceramics on the basis of calcium carbonate.