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.     

Interventional radiology in the acute pediatric abdomen

This article addresses the most common types of interventional procedures performed in the pediatric abdomen. Nonvascular interventions are stressed because they are more common than vascular interventions.     

KINETIC AND TRACER STUDIES ON METHANOL CONVERSION OVER SUPPORTED PLATINUM CATALYSTS

Hydrogen-deuterium exchange in methanol over Al₂,O₃, platinum black and alumina supported platinum catalysts have been investigated by means of mass spectrometry. The hydrogen-deuterium exchange proceeds faster over Pt/Al₂O₃ than either platinum black or alumina, and the rate (as well as the rate of dimethyl ether formation) increases with platinum dispersion. From the reactions CH₃OH + D₂, CD₃OH + H₂ and CD₃OH + D₂ the different exchange rates of the CH₃ and OH groups (R₁, and R₂, respectively) were determined. For all catalysts studied the exchange in the OH group was two or three orders of magnitude faster than CH₃ group. Exchange in the methyl group needs higher activation energy: R₁/R₂ ratio increases with temperature. Catalyst pretreatment has an important effect: higher activation temperature results in a higher R₁/R₂ ratio.

A methematical method is suggested for the evaluation of exchange rates of a molecule with two different types of hydrogen and a model is given for the interpretation of measured data: methanol is activated mainly on Al₂,O₃, forming surface methoxide groups on the Lewis acidic sites. This methoxide can react with deuterium atoms having been activated over platinum sites. With increasing dispersion the metal-support interface is enhanced which leads to higher rate of exchange.     

Differential Display of Investigative Behavior Permits Discrimination of Scent Signatures from Familiar and Unfamiliar Socially Dominant Female Marmoset Monkeys (Callithrix jacchus)

The hypothesis was tested that marmosets have differential displays of investigatory behavior towards circumgenital scent marks from socially dominant females based on degree of familiarity. In a series of two-choice behavioral discrimination bioassays, dominant males together with subordinate and dominant females were presented concurrently with scent secretions from familiar versus unfamiliar dominant females, and their investigative behaviors towards the scent were recorded. Test animals directed significantly different amounts of investigative behaviors towards familiar versus unfamiliar scents when the scent stimuli involved complete circumgenital scent marks, glandular secretion only, or urine only. When animals discriminated between the two scent samples, they did so by directing significantly increased amounts of behavior to scent from unfamiliar females. Chemical cues promoting differential displays of behavior to familiar versus unfamiliar scents appeared to be volatile in nature and were effective in the scent mark for at least one day following deposition. The reliable ability of marmosets to consistently discriminate between odors from familiar versus unfamiliar dominant females provides strong circumstantial evidence that individual female marmosets have distinct chemical signatures. The ability of marmosets to discriminate the odor from familiar versus unfamiliar dominant females may be important in the context of intergroup relations.     

Is cheating a human function? The roles of presence,state hostility,and enjoyment in an unfair video game

In sports and board games, when an opponent cheats, the other players typically greet it with disdain, anger, and disengagement. However, work has yet to fully address the role of the computer cheating in video games. In this study, participants played either a cheating or a non-cheating version of a modified open-source tower-defense game. Results indicate that when a computer competitor cheats, players perceive the opponent as being more human. Cheating also increases player aggravation and presence, but does not affect enjoyment of the experience. Additionally, players that firmly believed that their opponent was controlled by the computer exhibited significantly less state hostility compared to players that were less certain of the nature of their competitor. Game designers can integrate subtle levels of cheating into computer opponents without any real negative responses from the players. The results indicate that minor levels of cheating might also increase player engagement with video games.     

Hydrogenation of dinitriles on Raney-type Ni catalysts: kinetic and mechanistic aspects

The mechanism of the hydrogenation of aliphatic C₄–C₆ dinitriles (succinonitrile, glutaronitrile, and adiponitrile) over Raney-type Ni catalysts was investigated in a fed-batch autoclave at 350 K and 5.0 MPa. The results are interpreted based on the strength of adsorption, the interaction with the solvent and intramolecular interactions. The kinetics of the hydrogenation of aliphatic dinitriles is highly dependent on the hydrocarbon chain length. Short dinitriles like succinonitrile adsorb stronger on the catalyst surface than longer dinitriles like adiponitrile. The yield of the intermediate aminonitriles decreases with increasing hydrocarbon chain length, due to the enhanced competitiveness of dinitrile and aminonitrile for the same active sites. It is proposed that the reactivity of dinitriles and aminonitriles is caused by difference in solvent interaction. It is remarkable that the stronger the adsorption, the higher the reactivity. The reactivity decreases in the order: succinonitrile > glutaronitrile > adiponitrile. In contrast, the reaction rate of the aminonitriles is fairly independent of the hydrocarbon chain length. The formation of undesired secondary amines in the form of cyclic compounds is under kinetic control and increases with decreasing chain length. It is found that adiponitrile can be very selectively hydrogenated to primary diamines. Promoting Raney-type Ni catalysts with traces of Mo, Cr or Fe enhances the performance in the hydrogenation of dinitriles. This gives the best opportunity for process improvement towards the desired primary amines.     

Interleukin‐4‐Clicked Surfaces Drive M2 Macrophage Polarization

Driving macrophage (M?) polarization into the M2 phenotype provides potential against inflammatory diseases. Interleukin‐4 (IL‐4) promotes polarization into the M2‐M? phenotype, but its systemic use is constrained by dose‐limiting toxicity. Consequently, we developed IL‐4‐decorated surfaces aiming at sustained and localized activity. IL‐4 muteins were generated by genetic code expansion; Lys42 was replaced by unnatural amino acids (uAAs). Both muteins showed cell‐stimulation ability and binding affinity to IL4Rα similar to those of wt‐IL‐4. Copper‐catalyzed (CuAAC) and copper‐free strain‐promoted (SPAAC) 1,3‐dipolar azide–alkyne cycloadditions were used to site‐selectively anchor IL‐4 to agarose surfaces. These surfaces had sustained IL‐4 activity, as demonstrated by TF‐1 cell proliferation and M2, but not M1, polarization of M‐CSF‐generated human M?. The approach provides a blueprint for the engineering of cytokine‐activated surfaces profiled for sustained and spatially controlled activity.     

Simulation of ALTEA calibration data with PHITS,FLUKA and GEANT4

The ALTEA-Space detector has been calibrated by testing its response to several monochromatic beams. These measurements provided energy-deposition spectra in silicon of 100, 600 and 1000 MeV/nucleon ¹²C and 200 and 600 MeV/nucleon ⁴⁸Ti. The results have been compared to three Monte Carlo transport codes, namely PHITS, GEANT4 and FLUKA. Median, full width at half maximum (FWHM) and interquartile range (IQR) have been calculated for all datasets to characterize location, width and asymmetry of the energy-deposition spectra. Particular attention has been devoted to the influence of δ rays on the shape of the energy-deposition spectrum, both with the help of analytical calculations and Monte Carlo simulations. The two approaches proved that, in this range of projectile charge, projectile energy and detector size, the leakage of secondary electrons might introduce a difference between the energy-loss and energy-deposition spectrum, in particular by changing the location, width and symmetry of the distribution. The overall agreement between the Monte Carlo predictions and the measurements is fair and makes PHITS, FLUKA and GEANT4 all possible candidates for simulating ALTEA-Space experiment.     

Scaling Effect on the Dielectric Constant in Ba(Ti x Zr1−x )O3 Thin Films

Recent work on PZT and BST thin films reveal a thickness dependence of the dielectric constant for a film thickness below 100 nm. This effect is commonly attributed to an interfacial layer between the electrode and the dielectric film (dead layer). In this contribution we report on the influence of the film thickness on the dielectric constant of Ba(Ti_xZr_{1 – x})O₃ thin films with different Zr-contents (x = 0–30 at.%). The films were prepared by chemical solution deposition (CSD) with thickness between 30 and 350 nm.The electrical characterization was performed in a temperature range between 25 and 200C. Results were interpreted with respect to the formation of a serial dead layer capacitance.