A conducting polymer/Ag nanoparticle composite as a nitrate sensor

A novel electrochemical sensor was fabricated by electrodeposition of silver nanoparticles on pre-synthesized polypyrrole (PPy), to form a PPy/Ag composite matrix on a glassy carbon electrode. The electrochemical sensor exhibited strong catalytic activity with regards to nitrate reduction. Scanning electron microscopy and cyclic voltammetry were used for the characterization of the composite. The detection limit of nitrate was found to be 5 μM. Moreover, the sensor showed excellent sensitivity, selectivity, and stability.     

A Nitric Oxide-Responsive Quorum Sensing Circuit in Vibrio harveyi Regulates Flagella Production and Biofilm Formation

Cell signaling plays an important role in the survival of bacterial colonies. They use small molecules to coordinate gene expression in a cell density dependent manner. This process, known as quorum sensing, helps bacteria regulate diverse functions such as bioluminescence, biofilm formation and virulence. In Vibrio harveyi, a bioluminescent marine bacterium, four parallel quorum-sensing systems have been identified to regulate light production. We have previously reported that nitric oxide (NO), through the H-NOX/HqsK quorum sensing pathway contributes to light production in V. harveyi through the LuxU/LuxO/LuxR quorum sensing pathway. In this study, we show that nitric oxide (NO) also regulates flagellar production and enhances biofilm formation. Our data suggest that V. harveyi is capable of switching between lifestyles to be able to adapt to changes in the environment.     

When power does not corrupt: Superior individuation processes among powerful perceivers.

To examine whether powerful people fail to individuate the less powerful, the authors assigned participants to either a high-power or low-power role for a computer E-mail role play. In 3 studies, participants in the high-power role made decisions and determined the outcomes of interactions; low-power role players had no power and relied on high-power targets for outcome decisions. Studies 1 and 2 found that high-power perceivers better individuated low-power targets. Study 3 demonstrated that high-power role players' superior judgment can be impaired by including a task that directs their responsibility toward organizational rather than interpersonal concerns. In all, results suggest that the effect of power on social judgment may be more complex and multifaceted than has previously been acknowledged. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brain evoked potentials reflect how emotional faces influence our decision making.

Emotion is usually not discussed as a relevant variable in rational models of decision making—but may be one. The present electroencephalographic study demonstrates the influence of emotional primes (angry, happy faces) on purchase decisions. In a within-subject design, pictures of an apartment were shown to participants who then had to make Go/NoGo decisions on whether to rent it. Their decision should be based either on its price or on its brightness. In two thirds of the trials, emotional prime pictures of happy versus unhappy faces preceded the purchase target (apartment); in one third of the trials no prime was given. Response certainty was evaluated by means of reaction times (RT) and peak amplitude of the event-related potential N200. Facial primes accelerated decisions (RT) irrespective of affective expression. Positive face primes elicited larger N200 amplitudes during purchase decision compared to negative ones. Price-based decisions were made faster and elicited larger N200 than brightness-based decisions. These results support the cognitive-tuning model of decision making and validate the N200 as sensitive measure for the interplay of cognitive and affective aspects in decision making. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute health effects from exposure to indoor ultrafine particles—A randomized controlled crossover study among young mild asthmatics

Particulate matter is linked to adverse health effects, however, little is known about health effects of particles emitted from typical indoor sources. We examined acute health effects of short-term exposure to emissions from cooking and candles among asthmatics. In a randomized controlled double-blinded crossover study, 36 young non-smoking asthmatics attended three exposure sessions lasting 5 h: (a) air mixed with emissions from cooking (fine particle mass concentration): (PM_2.5: 96.1 μg/m³), (b) air mixed with emissions from candles (PM_2.5: 89.8 μg/m³), and c) clean filtered air (PM_2.5: 5.8 μg/m³). Health effects (spirometry, fractional exhaled Nitric Oxide [FeNO], nasal volume and self-reported symptoms) were evaluated before exposure start, then 5 and 24 h after. During exposures volatile organic compounds (VOCs), particle size distributions, number concentrations and optical properties were measured. Generally, no statistically significant changes were observed in spirometry, FeNO, or nasal volume comparing cooking and candle exposures to clean air. In males, nasal volume and FeNO decreased after exposure to cooking and candles, respectively. Participants reported additional and more pronounced symptoms during exposure to cooking and candles compared to clean air. The results indicate that emissions from cooking and candles exert mild inflammation in asthmatic males and decrease comfort among asthmatic males and females.     

Reversible Carbon-Carbon Bond Cleavage of a 3-Vinyl-1-Cyclopropene by Rh(I). Molecular Structures of Two Sterically Crowded 1,2,3,5-η-Pentadienediyl Complexes of Rh(III)

1,2,3-Tri-tert-butyl-3-vinyl-1-cyclopropene 6a reacts with [RhCl(C₂H₄)]₂ to give the dimeric 1,2,3,5-η-pentadienediyl complex 7a . The cyclopentadienyl derivative of this complex, 8a , is obtained by reaction of 7a with T1(C₅H₅). Crystal structures of both 7a and 8a were determined: 7a ; orthorhombic, Pbcn, a = 28.136 (4) Å, b = 10.637 (2) Å, c = 12.154 (2) Å, V = 3637.6 (1.2) ų, and Z = 4 : 8a ; triclinic, P 1 -bar, a = 9.906 (2) Å, b = 9.736 (2) Å, c = 12.126 (2) Å, α = 76.07 (2)°, β = 78.21 (2)°, γ = 65.34 (2)°, V = 1024.6 (3) ų, and Z = 2. Treatment of 7a with one equivalent of PMe₃ per Rh center results in regeneration of the vinylcyclopropene, demonstrating the reversibility of the ring opening reaction. Deuterium labelling studies show that both the ring opening and closing reactions proceed with retention of configuration at the vinyl olefin. Thus the trans-deuterated vinylcyclopropene 6b reacts with [RhCl(C₂H₄)₂]₂ to give 7b in which deuterium is located exclusively in the syn position. Treatment of 7b with T1(C₅H₅) yields 8b . Treatment of 7b with one equivalent of PMe₃ per Rh center results in formation of 6b as the sole organic product. Unlike their triphenyl relative 2 , the tri-Bu complexes 7a , 7b, 8a , and 8b are stereochemically rigid in solution at room temperature, and do not undergo an η³ → η¹ → η³ isomerization on the NMR time scale. However, after prolonged heating, syn-anti site exchange of H and D slowly takes place with 8b .     

A social relations analysis of agreement in liking judgments.

Using a round-robin design in which every subject served both as judge and target, subjects made liking judgments, trait ratings, and physical attractiveness ratings of each other on each of 4 days. Although there was some agreement in the liking judgments, most of the variance was due to idiosyncratic preferences for different targets. Differences in evaluations were due to at least 2 factors: disagreements in how targets were perceived (is this person honest?) and disagreements in how to weight the trait attributes that predicted liking (is honesty more important than friendliness?) When evaluating the targets in specific roles (as a study partner), judgments showed much greater agreement, as did the weights of the trait attributes. A 2nd study confirmed the differential weighting of trait attributes when rating liking in general and the increased agreement when rating specific roles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Raman spectroscopic evidence for the formation of silicomolybdic entities on a Mo/HY zeolite catalyst

Mo/Ze catalysts prepared by incipient wetness impregnation of a Faujasite zeolite with ammonium heptamolybdate solutions have been characterized after calcination at 500 °C and transfer in wet atmosphere. Raman spectroscopy clearly evidences the formation of [SiMo₁₂O₄₀]⁴⁻ heteropolyanions. This formation, through extraction of Si atoms, is not observed before the calcination, the Anderson [AlMo₆O₂₄H₆]³⁻ entity being the main species formed during the impregnation–maturation.