Three-dimensional reconstruction of a plant dictyosome from series of ultrathin sections using computer image processing

A single dictyosome from an actively secreting ovary gland cell of Aptenia cordifolia has been reconstructed in 3-D from a series of twenty-nine electron micrographs by computer image processing. The reconstruction is presented under different viewing angles in the form of shaded perspective displays. From these displays the entire dictyosome, surrounded by numerous vesicles, appears to be more a spherical than a flat body. The plate-like region of the dictyósome is demonstrated when only a portion of the electron micrographs is used for the image processing, leading to ‘cut-off’ displays. Since some upper planes were removed, such ‘cut-off’ displays revealed both tubular connections between cisternae of the dictyosome and the neighbouring endoplasmic reticulum as well as tubular continuities between adjacent Golgi cisternae within the same stack. Possible consequences of both types of interconnections on transport and processing of proteins and glycoproteins are discussed.     

Exploring the Influence of Personality on Depressive Symptoms and Self-Esteem Across a Significant Life Transition.

This study investigates the influence of personality on adjustment to a particular life transition, community relocation. Participants were 285 women (average age=69.5) who were interviewed once before they moved, and then multiple times after the move. Within the context of this multiwave design, personality traits were used to predict changes in depressive symptoms (DS) and self-esteem (SE) across the move. Neuroticism and Openness to Experience predicted increases in DS over time, whereas Extraversion and Openness predicted increases in SE. Stressful reactions to the move and sense of mastery about the move partially mediated these effects. The study documents the dynamic influence of personality on positive and negative aspects of adjustment and investigates differing routes through which such effects occur. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evolution of Texture in Rhabdophane-Derived Monazite Coatings

Microstructure and texture development of fiber coatings of rhabdophane-sol-derived monazite was studied. As-deposited textures and orientation relationships during phase transformations were determined by TEM. Monazite coatings had a crystallographic texture relict from that of as-deposited rhabdophane, with layers of rod-shaped particles that changed orientation by 90° across layers. Heat treatment at 1200°C of minicomposites with these coated fibers caused considerable monazite grain coarsening, and disappearance of the texture.     

Microwave Sintering of Alumina at 2.45 GHz

The sintering kinetics and microstructural evolution of alumina tubes (∼17 mm length, ∼9 mm inner diameter, and ∼11 mm outer diameter) were studied by conventional and microwave heating at 2.45 GHz. Temperature during microwave heating was measured with an infrared pyrometer and was calibrated to ±10°C. With no hold at sintering temperature, microwave-sintered samples reached 95% density at 1350°C versus 1600°C for conventionally heated samples. The activation energy for microwave sintering was 85 ± 10 kJ/mol, whereas the activation energy for conventionally sintered samples was 520 ± 14 kJ/mol. Despite the difference in temperature, grains grew from ∼1.0 μm at 86% density to ∼2.6 μm at 98% density for both conventionally sintered and microwave-sintered samples. The grain size/density trajectory was independent of the heating source. It is concluded that the enhanced densification with microwave heating is not a consequence of fast-firing and therefore is not a result in the change in the relative rates of surface and grain boundary diffusion in the presence of microwave energy.     

Creep Mechanism of Polycrystalline Yttrium Aluminum Garnet

The high-temperature deformation behavior of a fine-grained polycrystalline yttrium aluminum garnet (YAG) was studied in the temperature range of 1400° to 1610°C using constant strain rate compression tests under strain rates ranging from 10⁻⁵/s to 10⁻³/s. The stress exponent of the creep rate, the activation energy in comparison with that for single-crystal YAG, and the grain size dependence suggest that Nabarro–Herring creep rate limited by the bulk diffusion of one of the cations (Y or Al) is the operative mechanism.     

Identification of Phenazine-Based MEMO1 Small-Molecule Inhibitors: Virtual Screening,Fluorescence Polarization Validation,and Inhibition of Breast Cancer Migration

Phosphorylation-dependent protein–protein interactions play a significant role in biological signaling pathways; therefore, small molecules that are capable of influencing these interactions can be valuable research tools and have potential as pharmaceutical agents. MEMO1 (mediator of ErbB2-cell driven motility) is a phosphotyrosine-binding protein that interacts with a variety of protein partners and has been found to be upregulated in breast cancer patients. Herein, we report the first small-molecule inhibitors of MEMO1 interactions identified through a virtual screening platform and validated in a competitive fluorescence polarization assay. Initial structure–activity relationships have been investigated for these phenazine-core inhibitors and the binding sites have been postulated using molecular dynamics simulations. The most potent biochemical inhibitor is capable of disrupting the large protein interface with a K_I of 2.7 μm . In addition, the most promising phenazine core compounds slow the migration of breast cancer cell lines in a scratch assay.     

The effect of solidification direction with respect to gravity on ice-templated TiO2 microstructures

Unidirectional ice-templating produces materials with aligned, elongated pores via: (i) directional solidification of particle suspensions wherein suspended particles are rejected and incorporated between aligned dendrites, (ii) sublimation of the solidified fluid, and (iii) sintering of the particles into elongated walls which are templated by the ice dendrites. Most ice-templating studies utilize upward solidification techniques, where solid ice is located at the bottom of the solidification mold (closest to the cold source), the liquid suspension is above the ice, and the solidification front advances upward, against gravity. Liquid water reaches its maximum density at 4 °C; thus, liquid nearest the solid/liquid interface, at 0ºC, is less dense than warmer liquid above (up to 4 °C, above which, a density inversion occurs, and liquid density decreases with increasing temperature). The lower density liquid nearest the solidification front is thus expected to rise due to buoyancy, promoting convective fluid motion in the liquid during solidification. Here, we investigate the effect of solidification direction with respect to the direction of gravity on ice-templated microstructures to study the role of buoyancy-driven fluid motion during solidification. We hypothesize that, for upward solidification, the convective fluid motion that results from the liquid density gradient occurs near the solidification front. For downward solidification, we expect that this fluid motion occurs farther away from the solidification front. Aqueous suspensions of TiO₂ nanoparticles (10–30 nm in size, 10, 15, and 21 vol.%) are solidified upward (against gravity, with ice on bottom and water on top), downward (water on bottom, ice on top), and horizontally (perpendicular to gravity). Microstructural investigation of sintered samples shows evidence of buoyancy-driven, convective fluid flow during solidification for samples solidified upwards (against gravity), including (i) tilting of the wall (and pore) orientation with respect to the induced temperature gradient, (ii) ice lens defects (cracks oriented perpendicular to the freezing direction), and (iii) radial macrosegregation. These features are not observed for downward nor horizontal solidification configurations, consistent with the hypothesis that convective fluid motion does not interact directly with the solidification front for downward solidification.     

Reaction kinetics and optimization of the copper-catalyzed oxidation of ApoA-1M

This paper summarizes the development of an optimized Cu(II)-catalyzed oxidation process for the dimer formation of ApoA-1M, the protein component of an HDL mimic with potential efficacy in atherosclerotic plaque reduction. This oxidation represents a major processing step in the large-scale manufacture of ApoA-1M dimer. The development approach utilizes reaction kinetic modeling, design of experiment, and neural network analysis to establish a quantitative basis for specification of process operating ranges. This work is thus an example of quality by design (QbD) principles where a systematic mechanistic understanding combined with multivariate analysis is integral to process development. Operating within the defined optimum window of operation resulted in both enhanced performance and robustness for the oxidation step in the piloting and manufacturing campaigns.     

Factors that Influence the Perception of Feedback Delivered by a Pedagogical Agent

Three experiments were conducted to assess the relative importance of speech parameters and facial expressions in the delivery of feedback by a pedagogical agent. In Experiment 1, we manipulated linguistic form (i.e., positive, negative, or neutral terms), rate, pitch, pause, and emphasis. In Experiment 2, we manipulated eye size, mouth curve, brow height, and brow curve. In a third study, both speech parameters and facial expressions were manipulated. In all three experiments, the participants were asked to indicate how positive or negative the agent's feedback seemed to be. Across the studies, the variables collectively accounted for a significant amount of the variance. More specifically, the linguistic expressions and mouth curve emerged as significant predictors of the participants' ratings. This suggests that these two features should be implemented by developers wishing to provide appropriate feedback in their pedagogical agents.     

Coarse-Grained Interaction of a Fluid with a Physically-Patterned Solid Surface: Application to Nanodroplet Wetting

We derive coarse-grained potentials to describe the interaction of a physically adsorbed, fluid-phase atom with a solid surface that is patterned with an array of rectangular or cylindrical pillars. The coarse-grained potentials are used in molecular dynamics simulations to probe the wetting of a Lennard-Jones liquid droplet on various patterned solid surfaces. Our results, which indicate that surface patterning can significantly influence wetting, are in agreement with previous studies.