Ratiometric Detection of Glutathione Based on Disulfide Linkage Rupture between a FRET Coumarin Donor and a Rhodamine Acceptor

Abnormal levels of glutathione, a cellular antioxidant, can lead to a variety of diseases. We have constructed a near-infrared ratiometric fluorescent probe to detect glutathione concentrations in biological samples. The probe consists of a coumarin donor, which is connected through a disulfide-tethered linker to a rhodamine acceptor. Under the excitation of the coumarin donor at 405 nm, the probe shows weak visible fluorescence of the coumarin donor at 470 nm and strong near-infrared fluorescence of the rhodamine acceptor at 652 nm due to efficient Forster resonance energy transfer (FRET) from the donor to the acceptor. Glutathione breaks the disulfide bond through reduction, which results in a dramatic increase in coumarin fluorescence and a corresponding decrease in rhodamine fluorescence. The probe possesses excellent cell permeability, biocompatibility, and good ratiometric fluorescence responses to glutathione and cysteine with a self-calibration capability. The probe was utilized to ratiometrically visualize glutathione concentration alterations in HeLa cells and Drosophila melanogaster larvae.     

Reaction of carboxylic acids on CeO2(111) and CeO2(100)

The reactions of HCOOH and CH₃COOH on CeO₂(111) and CeO₂(100) were studied using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). The carboxylic acids were found to dissociate on both surfaces to form carboxylates. Adsorbed formates and acetates decomposed near 600 K to produce primarily the dehydration products CO and CH₂CO, respectively. This result is consistent with previous studies which have indicated that the ease of reduction of the oxide is the primary factor in determining the selectivity for dehydration versus dehydrogenation during carboxylate decomposition. In addition to CO and CO₂, small amounts of formaldehyde were produced during formate decomposition on both CeO₂(111) and CeO₂(100). In contrast, acetone was observed as a product during acetate decomposition only on the CeO₂(111) surface.     

Intellectual performance and ego depletion: Role of the self in logical reasoning and other information processing.

Some complex thinking requires active guidance by the self, but simpler mental activities do not. Depletion of the self's regulatory resources should therefore impair the former and not the latter. Resource depletion was manipulated by having some participants initially regulate attention (Studies 1 and 3) or emotion (Study 2). As compared with no-regulation participants who did not perform such exercises, depleted participants performed worse at logic and reasoning (Study 1), cognitive extrapolation (Study 2), and a test of thoughtful reading comprehension (Study 3). The same manipulations failed to cause decrements on a test of general knowledge (Study 2) or on memorization and recall of nonsense syllables (Study 3). Successful performance at complex thinking may therefore rely on limited regulatory resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-regulation and extended now: Controlling the self alters the subjective experience of time.

These studies investigated self-regulation and subjective experience of time from the perspective of the regulatory resource model. Studies 1-2 showed that participants who were instructed to regulate their emotions while viewing a film clip perceived that the film lasted longer than participants who did not regulate their emotions. In Study 3, participants provided time estimates during a resource-depleting or nondepleting task. Subsequent task persistence was measured. Time perceptions mediated the effect of initial self-regulation on subsequent self-regulated performance. In Study 4, participants performed either a resource-depleting or a nondepleting thought-listing task and then performed a different regulatory task. Compared with nondepleted participants, depleted participants persisted less on the 2nd task but estimated that they had persisted longer. Subjective time estimates statistically accounted for reduced persistence after depletion. Together, results indicate people believe that self-regulatory endeavors last overly long, a belief that may result in abandonment of further self-control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A silicon test chip for the thermomechanical analysis of MEMS packagings

This paper reports on a method for the investigation of mechanical stress on MEMS sensor and actuator structures due to packaging processes. A silicon test chip is developed and manufactured to validate the simulation results. Finite element analysis (FEA) is used to optimize the geometric parameters and to find a stress sensitive sensor geometry. A diaphragm structure is used as mechanical amplifier for bulk induced stresses during the packaging process. Piezo resistive solid state resistors are doped into the surface of the chip to measure the stress in the diaphragms and at the contact pads being most significant locations for analysis. A high precision ohmmeter was used to measure the resistance prior and past the packaging process. The captured data allows for computation of the resulting stress loads in magnitude. Therefore, a stress evaluation of different packaging technologies is conducted and the impact of the packaging process on reliability can be estimated immediately.     

Is the allure of self-esteem a mirage after all?

Comments on the original article "Do people's self-views matter? Self-concept and self-esteem in everyday life," by W. B. Swann, Jr., C. Chang-Schneider, and K. L. McClarty (see record 2007-01685-002). Swann et al argued that people's self-views, and their global self-esteem in particular, yield a suite of behavioral effects that are beneficial to the individual and to society at large. The Swann et al article is the latest link in a debate on the causal utility of self-esteem. Specifically, the article is a reply to a report published by the American Psychological Society Task Force on Self-Esteem (Baumeister, Campbell, Krueger, & Vohs, 2003). As members of that task force, the current authors wish to express their broad agreement with Swann et al. At the same time, in the comment presented here, they clarify pockets of disagreement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feeling duped: Emotional, motivational, and cognitive aspects of being exploited by others.

Feeling duped is an aversive emotional response to the perception of having been taken advantage of in a interpersonal transaction (primarily those involving economic exchange), partly as a result of one's own decisions. The actual likelihood of being duped, as well as the heightened vigilance for it, should increase as a function of opportunity (e.g., information asymmetry that gives one side a big advantage in knowledge) and motivation (e.g., an exceptionally huge payoff may make it worth defrauding a long-term business partner). Being duped produces an aversive self-conscious emotion with a threat of self-blame. There appears to be stable individual differences in the motivation (called sugrophobia) to avoid being a sucker. High sugrophobes will be vigilant and skeptical of potential deals. Low sugrophobes may not even realize in some instances that they were duped. The aversive reaction to feeling duped stimulates counterfactual ruminations that may intensify sugrophobia but also aids in extracting useful lessons. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Introduction to special issue: Emotion and decision making.

It is a perennial debate in the social sciences: Are emotions the bane of optimal behavior, or do emotions contribute invaluably to the process of decision making to improve human outcomes? The debate continues, in part because both sides can point to rigorous data and important theories that support their claims. The articles in this special issue advance both sides of that debate and, in doing so, help point the way toward a more integrative solution. The papers in this special issue approach the topics of emotion and decision making as a set, with an eye toward integrating the role of emotion in decision making or the emotional consequences of decision making. The papers in this special issue not only introduce readers to core concepts essential to choice and emotion, but also develop sophisticated integrative models. These models promise to advance the fields of psychology, marketing, and economics toward a joint science involving the complex interplay between emotions and decisions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Photolithographic patterning of organic photodetectors with a non-fluorinated photoresist system

We report on the fabrication of organic photodetectors (OPD) based on isolated islands of P3HT:PCBM. Pattern transfer to the active material was done with photolithography based on non-fluorinated solvents and the excessive organic semiconductor was removed with oxygen plasma reactive ion etching. The photoresist system used was found to be benign to the P3HT:PCBM layer as confirmed by absorption, thickness and roughness measurements. Current–voltage characteristics and external quantum efficiency (EQE) remained unchanged after the patterning process. It was demonstrated that it is possible to photolithographically pattern isolated islands with 200 μm edge length with the same dark current density (<10⁻⁵ A/cm² at −2 V bias voltage) and photocurrent density (>5 × 10⁻³ A/cm² at −2 V). Furthermore, concerning the solar cell performance, the patterned, small-area devices showed power conversion efficiency of 2.1% and fill-factor of 60%. Dark current was observed to depend on the size of the remaining semiconductor island, which was demonstrated on OPDs with diameter of 50 μm. The presented results show the feasibility of fabrication of isolated devices based on organic semiconductors patterned with non-fluorinated photolithography.     

Redox Isotherms for Vanadia Supported on Zirconia

Calcination of a Pt/Ba/CeO₂ catalyst at 700 °C and subsequent reduction in hydrogen, carbon monoxide or propene at 350–550 °C resulted in a considerable improvement of its NO _x storage-reduction (NSR) properties compared to those of a freshly prepared Pt/Ba/CeO₂ catalyst. This behavior is traced back to the temporary formation of BaPtO₃ perovskite which leads after reduction to well-distributed Pt particles in intimate contact with the barium-containing phases. The oxidation and reduction of platinum is reversible which can be exploited for the design of “self-regenerating” NSR-catalysts under lean (>600 °C) and rich (>400 °C) reaction conditions. The formation of the BaPtO₃-perovskite may not only be interesting for NSR-catalysis, but generally for Pt-based catalysts where a high dispersion of Pt is important.