A spatially and chemically defined platform for the uniform growth of human pluripotent stem cells

We report the design of a chemically defined platform engineered for the culture of human pluripotent stem cells (hPSCs) that supports the long-term maintenance of self-renewing hPSC populations in a more uniform manner than standard culture systems. Microcontact printing (μCP) of alkanethiol self-assembled monolayers (SAMs) was used to spatially direct hPSC adherence. This technique not only establishes control over hPSC colony size and shape but also preserves genetic stability and provides unprecedented uniformity in the pluripotency of hPSC populations that is quantitatively assessed in the present study.     

Synthesis, characterization, and direct intracellular imaging of ultrasmall and uniform glutathione-coated gold nanoparticles

Gold nanoparticles (AuNPs) with core sizes below 2 nm and compact ligand shells constitute versatile platforms for the development of novel reagents in nanomedicine. Due to their ultrasmall size, these AuNPs are especially attractive in applications requiring delivery to crowded intracellular spaces in the cytosol and nucleus. For eventual use in vivo, ultrasmall AuNPs should ideally be monodisperse, since small variations in size may affect how they interact with cells and how they behave in the body. Here we report the synthesis of ultrasmall, uniform 144-atom AuNPs protected by p-mercaptobenzoic acid followed by ligand exchange with glutathione (GSH). Quantitative scanning transmission electron microscopy (STEM) reveals that the resulting GSH-coated nanoparticles (Au(GSH)) have a uniform mass distribution with cores that contain 134 gold atoms on average. Particle size dispersity is analyzed by analytical ultracentrifugation, giving a narrow distribution of apparent hydrodynamic diameter of 4.0 ± 0.6 nm. To evaluate the nanoparticles' intracellular fate, the cell-penetrating peptide TAT is attached noncovalently to Au(GSH), which is confirmed by fluorescence quenching and isothermal titration calorimetry. HeLa cells are then incubated with both Au(GSH) and the Au(GSH)-TAT complex, and imaged without silver enhancement of the AuNPs in unstained thin sections by STEM. This imaging approach enables unbiased detection and quantification of individual ultrasmall nanoparticles and aggregates in the cytoplasm and nucleus of the cells.     

Patterned dispersion of nanoparticles in hydrogels using microfluidics

Uniform dispersions of nanoparticles in polymers have received increasing attention for optical applications, and patterned dispersions could enhance the potential applications. Methods for achieving patterned dispersions of nanoparticles in polymers are limited. However, microfluidics represents one technique that holds promise for this application. To demonstrate proof-of-concept, model samples of fluorescent polystyrene nanoparticles dispersed in hydrogels were chosen. High fidelity staircase patterns were produced, imaged using fluorescence microscopy and quantified using image analysis software. The results demonstrate the suitability of microfluidics for creating patterned dispersions of nanoparticles in polymers and establishes the foundation for enabling optical applications.     

Orbital spaceflight during pregnancy shapes function of mammalian vestibular system.

Pregnant rats were flown on the NASA Space Shuttle during the early developmental period of their fetuses' vestibular apparatus and onset of vestibular function. The authors report that prenatal spaceflight exposure shapes vestibular-mediated behavior and central morphology. Postflight testing revealed (a) delayed onset of body righting responses, (b) cardiac deceleration (bradycardia) to 70° head-up roll, (c) decreased branching of gravistatic afferent axons, but (d) no change in branching of angular acceleration receptor projections with comparable synaptogenesis of the medial vestibular nucleus in flight relative to control fetuses. Kinematic analyses of the dams' on-orbit behavior suggest that, although the fetal otolith organs are unloaded in microgravity, the fetus' semicircular canals receive high levels of stimulation during longitudinal rotations of the mother's weightless body. Behaviorally derived stimulation from maternal movements may be a significant factor in studies of vestibular sensory development. Taken together, these studies provide evidence that gravity and angular acceleration shape prenatal organization and function within the mammalian vestibular system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between personality psychopathology and aggressive behavior in research volunteers.

Theorists and clinicians have long believed that personality psychopathology is a risk factor for aggressive behavior. Previous investigations in this area, however, have provided mixed results. In this study, the relationship between personality psychopathology and aggressive behavior was examined in 137 research volunteers. The influences of gender and coexisting major mental disorders were statistically controlled. Aggressive behavior was associated with criteria for 7 of the I I personality disorders listed in the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.). Except for schizoid criteria, all relationships with aggressive behavior were in the positive direction. When all personality disorders were considered simultaneously, paranoid and passive-aggressive criteria were significant predictors of aggressive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Glass Formation and Polyamorphism in Rare-Earth Oxide–Aluminum Oxide Compositions

We report formation of single- and two-phase glasses from rare-earth oxide–alumina materials. Liquids with the Y₃Al₅O₁₂ and Er₃Al₅O₁₂ compositions underwent a liquid–liquid phase transition which resulted in glasses with a cloudy appearance due to spheroids of one glass in a matrix of a second glass. The two glasses were isocompositional within the limits of experimental error. Clear, brilliant, single-phase glasses were obtained from La₃Al₅O₁₂, ErLaYAl₅O₁₂, and compositions containing ≥5 mol% La₂O₃ substituted for the other rare-earth oxides. Formation of two glasses is attributed to nucleation and growth of the second liquid at a temperature below the equilibrium liquid–liquid transition temperature. Addition of lanthanum depresses the phase transition temperature below the glass transition temperature and the liquid–liquid phase transition is not observed. The results are discussed in the context of first-order liquid–liquid phase transitions (polyamorphism) and formation of single-phase glass from liquids that contain a high proportion of 4-coordinate aluminum ions.     

“Are You Kidding Me?”: The Role of Nonverbal Cues in the Verbal Accounting Process

This article reports on an investigation of 78 interactions for the messages sent by nonverbal cues in account sequences. Account elicitations and evaluations were rated based on vocal and facial behaviors communicating five messages: (a) positive or negative affect, (b) certainty or uncertainty, (c) understanding or confusion, (d) agreement or disagreement, and (e) belief or disbelief. We also coded the accounters' discourse that followed elicitations and evaluations to investigate the relationship between nonverbal messages and the account forms used by the teller. Our results showed that, even when controlling for what a person said, the messages sent by nonverbal cues could all predict subsequent account forms, although not always in the way expected. These results help our argument that nonverbal cues may be an important part of moving through account sequences, both on their own and when combined with verbal utterances.     

Challenges and potential payoff for crystalline oxides in wide bandgap semiconductor technology

While growth of wide bandgap semiconductor materials on crystalline oxides (sapphire, lithium gallate, lithium aluminate, zinc oxide and others) has become routine, growth of crystalline oxides on wide bandgap materials remains challenging and minimally explored. The potential payoff in terms of enhanced device performance, increased functionality and reliability warrants examining this option. This presentation aims at targeting key areas, where crystalline oxides could improve wide bandgap semiconductor device performance. Some of these include the use of ferroelectric oxides for power switching applications, oxides with anisotropic dielectric constants for high voltage termination and oxides with large electric flux density near breakdown. Unique polarization engineered structures are described that are enabled by using lithographically defined poled regions in a ferroelectric substrate. The desired crystalline oxide properties, potential implementation challenges and potential pitfalls will be discussed.     

Reduction of fumonisin B₁ in corn grits by twin-screw extrusion

Abstract: This study was designed to investigate the fate of fumonisins in flaking corn grits during twin‐screw extrusion by measuring fumonisin B₁ (FB₁) and its analogs with a mass balance approach. Food grade corn grits and 2 batches of grits contaminated with FB₁ at 10 and 50 μg/g by Fusarium verticillioides M‐2552 were processed with or without glucose supplementation (10%, w/w) with a twin‐screw extruder. Extrusion reduced FB₁ in contaminated grits by 64% to 72% without glucose and 89% to 94% with added glucose. In addition, extrusion alone resulted in 26% to 73% reduction in the levels of fumonisin B₂ and fumonisin B₃, while levels of both mycotoxins were reduced by >89% in extruded corn grits containing 10% glucose. Mass balance analysis showed that 38% to 46% of the FB₁ species detected in corn extruded with glucose was N‐(deoxy‐D‐fructos‐1‐yl)‐FB₁, while 23% to 37% of FB₁ species detected in extruded corn grits with and without added glucose was bound to the matrix. It was also found that the hydrolyzed form of FB₁ was a minor species in extruded corn grits with or without added glucose, representing <15% of the total FB₁ species present. Less than 46% of FB₁ originally present in corn grits could be detected in the fumonisin analogues measured in this study. Research is needed to identify the reaction products resulting from extrusion processing of fumonisin‐contaminated corn products. Practical Application: Twin‐screw extrusion is widely used in food industry for its versatility. This technology may reduce the level of fumonisins in corn particularly with added glucose.