AgAu Bimetallic Janus Nanoparticles and Their Electrocatalytic Activity for Oxygen Reduction in Alkaline Media

Bimetallic AgAu Janus nanoparticles were prepared by galvanic exchange reactions of 1-hexanethiolate-passivated silver (AgC6) nanoparticles with gold­(I)-mercaptopropanediol complex. The AgC6 nanoparticles were deposited onto a solid substrate surface by the Langmuir–Blodgett method such that the galvanic exchange reactions were limited to the top face of the nanoparticles that was in direct contact with the gold­(I) complex solution. The resulting nanoparticles exhibited an asymmetrical distribution not only of the organic capping ligands on the nanoparticle surface but also of the metal elements in the nanoparticle cores, in contrast to the bulk-exchange counterparts where these distributions were homogeneous within the nanoparticles, as manifested in contact angle, UV–vis, XPS, and TEM measurements. More interestingly, despite a minimal loading of Au onto the Ag nanoparticles, the bimetallic AgAu nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to the monometal AgC6 nanoparticles. Additionally, the electrocatalytic performance of the Janus nanoparticles was markedly better than the bulk-exchange ones, suggesting that the segregated distribution of the polar ligands from the apolar ones might further facilitate charge transfer from Ag to Au in the nanoparticle cores, leading to additional improvement of the adsorption and reduction of oxygen

Symptoms of Fern Distortion Syndrome Resulting from Inoculation with Opportunistic Endophytic Fluorescent <em>Pseudomonas</em> spp.

<div><p>Background</p><p>Fern Distortion Syndrome (FDS) is a serious disease of Leatherleaf fern (<i>Rumohra adiantiformis</i>). The main symptom of FDS is distortion of fronds, making them unmarketable. Additional symptoms include stunting, irregular sporulation, decreased rhizome diameter, and internal discoloration of rhizomes. We previously reported an association of symptoms with increased endophytic rhizome populations of fluorescent pseudomonads (FPs). The aim of the current study was to determine if FPs from ferns in Costa Rica with typical FDS symptoms would recreate symptoms of FDS.</p> <p>Methodology and Findings</p><p>Greenhouse tests were conducted over a 29-month period. Micro-propagated ferns derived from tissue culture were first grown one year to produce rhizomes. Then, using an 8×9 randomized complete block experimental design, 8 replicate rhizomes were inoculated by dipping into 9 different treatments before planting. Treatments included water without bacteria (control), and four different groups of FPs, each at a two concentrations. The four groups of FPs included one group from healthy ferns without symptoms (another control treatment), two groups isolated from inside rhizomes of symptomatic ferns, and one group isolated from inside roots of symptomatic ferns. Symptoms were assessed 12 and 17 months later, and populations of FPs inside newly formed rhizomes were determined after 17 months. Results showed that inoculation with mixtures of FPs from ferns with FDS symptoms, but not from healthy ferns, recreated the primary symptom of frond deformities and also the secondary symptoms of irregular sporulation, decreased rhizome diameter, and internal discoloration of rhizomes.</p> <p>Conclusions</p><p>These results suggest a model of causation of FDS in which symptoms result from latent infections by multiple species of opportunistic endophytic bacteria containing virulence genes that are expressed when populations inside the plant reach a minimum level.</p> </div

Overall Performances of Mammalian Classifiers Based on 5-fold Cross-validation Tests.

<p>(A) The ROC curve illustrating the performance for full transcript mode. (B) The ROC curve illustrating the performance for mature mRNA mode.</p

Recreation of FDS symptoms of reduced rhizome diameter.

<p>Inoculation with fluorescent pseudomonads from rhizomes and the rhizosphere of diseased plants. Representative examples of rhizomes on ferns 17 months after inoculation. A, B = bacteria from inside rhizomes of ferns with FDS symptoms (treatments 3A and 4A), C = rhizosphere bacteria from ferns with FDS symptoms (treatment 5A), D = bacteria from inside rhizomes of healthy ferns (treatment 2B), E = water control.</p

Fluorescent Films Based on Molecular-Gel Networks and Their Sensing Performances

A pyrene-capped terthiophene of cholesteryl derivative (CholG-3T-Py) was designed, synthesized, and utilized for the fabrication of a fluorescent film. Unlike the commonly adopted direct-coating method, the film was fabricated by the physical immobilization of the fluorophore, CholG-3T-Py, onto a glass plate surface via preformed low-molecular-mass gelator (LMMGs)-based molecular-gel networks. The photophysical behavior of the film as prepared and its sensing performances to nitrobenzene (NB) were conducted after activation with toluene. It was found that the film as prepared and activated is sensitive to the presence of NB, and the sensing process is fully reversible. Furthermore, the effects of commonly found interferents, including structural analogues, raw materials, which are commonly used for the production of NB, and other nitroaromatics (NACs), on the sensing process were also tested. It was shown that only aniline and phenol possess slight interference. The present work not only extends the applications of LMMGs-based molecular gels but also provids a new approach for preparation of micro- and nano-structure-based fluorescent sensing films

Integrated Nanocavity Plasmon Light Sources for On-Chip Optical Interconnects

Next generation on-chip light sources require high modulation bandwidth, compact footprint, and efficient power consumption. Plasmon-based sources are able to address the footprint challenge set by both the diffraction limited of light and internal laser physics such as plasmon utilization. However, the high losses, large plasmonic-momentum of these sources hinder efficient light coupling to on-chip waveguides, thus, questioning their usefulness. Here we show that plasmon light sources can be useful devices; they can deliver efficient outcoupling power to on-chip waveguides and are able to surpass modulation speeds set by gain-compression. We find that waveguide-integrated plasmon nanocavity sources allow to transfer about ∼60% of their emission into planar on-chip waveguides, while sustaining a physical small footprint of ∼0.06 μm². These sources are able to provide output powers of tens of microwatts for microamp-low injection currents and reach milliwatts for higher pump rates. Moreover, the direct modulation bandwidth exceeds that of classical, gain compression-limited on-chip sources by more than 200%. Furthermore, these novel sources feature high power efficiencies (∼1 fJ/bit) enabled by both minuscule electrical capacitance and efficient internal photon utilization. Such strong light–matter interaction devices might allow redesigning photonic circuits that only demand microwatts of signal power in the future

Recreation of FDS symptoms of internal discoloration of rhizomes.

<p>Inoculation with fluorescent pseudomonads from rhizomes and the rhizosphere of diseased plants. A, B = bacteria from inside rhizomes of healthy ferns (treatments 2A and 2B), C = water control, D, E = bacteria from inside rhizomes of ferns with FDS symptoms (treatments 3A and 4A), F = rhizosphere bacteria from ferns with FDS symptoms (treatment 5A).</p

Intra-species variability in the Pb-BAFs of six wheat varieties before and after normalization.

<p>Intra-species variability in the Pb-BAFs of six wheat varieties before and after normalization.</p

Cross-Species Extrapolation of Models for Predicting Lead Transfer from Soil to Wheat Grain - Fig 2

<p>Relationship between Pb accumulation in wheat grain and soil properties (A, pH; B, LogOC).</p

Plant growth parameters and internal rhizome populations 17 months after inoculation with fluorescent pseudomonads.

1<p>Strains of fluorescent pseudomonads used in each treatment are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058531#pone-0058531-t001" target="_blank">Table 1</a>.</p>2<p>HRZ = Inside rhizomes of healthy-appearing ferns from a fernery in Florida without history of Benlate use; SRS = Rhizosphere (roots and rhizomes) of symptomatic ferns in Costa Rica; SRZ = inside rhizomes of symptomatic ferns in Costa Rica.</p>3<p>Mean of 8 replicate plants per treatment. Means followed by different letters are significantly different at <i>P</i> = 0.01.</p