Control of radiative processes using tunable plasmonic nanopatch antennas.

The radiative processes associated with fluorophores and other radiating systems can be profoundly modified by their interaction with nanoplasmonic structures. Extreme electromagnetic environments can be created in plasmonic nanostructures or nanocavities, such as within the nanoscale gap region between two plasmonic nanoparticles, where the illuminating optical fields and the density of radiating modes are dramatically enhanced relative to vacuum. Unraveling the various mechanisms present in such coupled systems, and their impact on spontaneous emission and other radiative phenomena, however, requires a suitably reliable and precise means of tuning the plasmon resonance of the nanostructure while simultaneously preserving the electromagnetic characteristics of the enhancement region. Here, we achieve this control using a plasmonic platform consisting of colloidally synthesized nanocubes electromagnetically coupled to a metallic film. Each nanocube resembles a nanoscale patch antenna (or nanopatch) whose plasmon resonance can be changed independent of its local field enhancement. By varying the size of the nanopatch, we tune the plasmonic resonance by ∼ 200 nm, encompassing the excitation, absorption, and emission spectra corresponding to Cy5 fluorophores embedded within the gap region between nanopatch and film. By sweeping the plasmon resonance but keeping the field enhancements roughly fixed, we demonstrate fluorescence enhancements exceeding a factor of 30,000 with detector-limited enhancements of the spontaneous emission rate by a factor of 74. The experiments are supported by finite-element simulations that reveal design rules for optimized fluorescence enhancement or large Purcell factors

Polarized recombination of acoustically transported carriers in GaAs nanowires

The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited electrons and holes in GaAs nanowires deposited on a SAW delay line on a LiNbO3 crystal. The carriers generated in the nanowire by a focused light spot are acoustically transferred to a second location where they recombine. We show that the recombination of the transported carriers occurs in a zinc blende section on top of the predominant wurtzite nanowire. This allows contactless control of the linear polarized emission by SAWs which is governed by the crystal structure. Additional polarization-resolved photoluminescence measurements were performed to investigate spin conservation during transport

Di-(2 ethylhexyl) phthalate and flutamide alter gene expression in the testis of immature male rats

We previously demonstrated that the androgenic and anti-androgenic effects of endocrine disruptors (EDs) alter reproductive function and exert distinct effects on developing male reproductive organs. To further investigate these effects, we used an immature rat model to examine the effects of di-(2 ethylhexyl) phthalate (DEHP) and flutamide (Flu) on the male reproductive system. Immature male SD rats were treated daily with DEHP and Flu on postnatal days (PNDs) 21 to 35, in a dose-dependent manner. As results, the weights of the testes, prostate, and seminal vesicle and anogenital distances (AGD) decreased significantly in response to high doses of DEHP or Flu. Testosterone (T) levels significantly decreased in all DEHP- treated groups, whereas luteinizing hormone (LH) plasma levels were not altered by any of the two treatments at PND 36. However, treatment with DEHP or Flu induced histopathological changes in the testes, wherein degeneration and disorders of Leydig cells, germ cells and dilatation of tubular lumen were observed in a dose-dependent manner. Conversely, hyperplasia and denseness of Leydig, Sertoli and germ cells were observed in rats given with high doses of Flu. The results by cDNA microarray analysis indicated that 1,272 genes were up-regulated by more than two-fold, and 1,969 genes were down-regulated in response to DEHP, Flu or both EDs. These genes were selected based on their markedly increased or decreased expression levels. These genes have been also classified on the basis of gene ontology (e.g., steroid hormone biosynthetic process, regulation of transcription, signal transduction, metabolic process, biosynthetic process...). Significant decreases in gene expression were observed in steroidogenic genes (i.e., Star, Cyp11a1 and Hsd3b). In addition, the expression of a common set of target genes, including CaBP1, Vav2, Plcd1, Lhx1 and Isoc1, was altered following exposure to EDs, suggesting that they may be marker genes to screen for the anti-androgenic or androgenic effects of EDs. Overall, our results demonstrated that exposure to DEHP, Flu or both EDs resulted in a alteration of gene expression in the testes of immature male rats. Furthermore, the toxicological effects of these EDs on the male reproductive system resulted from their anti-androgenic effects. Taken together, these results provide a new insight into the molecular mechanisms underlying the detrimental impacts of EDs, in regards to anti-androgenic effects in humans and wildlife

Polarization and temperature dependence of photoluminescence from zincblende and wurtzite InP nanowires

We use polarization-resolved and temperature-dependent photoluminescence of single zincblende (ZB) (cubic) and wurtzite (WZ) (hexagonal) InPnanowires to probe differences in selection rules and bandgaps between these two semiconductor nanostructures. The WZ nanowires exhibit a bandgap80meV higher in energy than the ZB nanowires. The temperature dependence of the PL is similar but not identical for the WZ and ZB nanowires. We find that ZB nanowires exhibit strong polarization parallel to the nanowire axis, while the WZ nanowires exhibit polarized emission perpendicular to the nanowire axis. This behavior is interpreted in terms of the different selection rules for WZ and ZB crystal structures.A.M., L.V.T., T.B.H., H.E.J., L.M.S., and J.M.Y.-R. acknowledge support from the Institute for Nanoscale Science and Technology of the University of Cincinnati and the National Science Foundation through Grant Nos. EEC/NUE 0532495 and ECCS 0701703. The Australian authors acknowledge support from the Australian Research Council. Y.K. acknowledges support by the Korean Science and Engineering Foundation KOSEF through Grant No. F01- 2007-000-10087-0

Polarized photoluminescence and time-resolved photoluminescence from single CdS nanosheets

We have utilized polarized low temperature photoluminescence (PL) to probe the electronic states and structural symmetries of individual CdS nanosheets. High resolution transmission electron microscopy measurements indicate highly crystalline material with different nanosheets exhibiting significant variations of the direction of the c axis, which are consistent with polarization measurements of PL from single CdS nanosheets. The quality of the nanosheets is reflected in measurements of exciton lifetimes of similar to 200 ps, a value significantly longer than observed for CdS nanowires whose diameter is the same as the thickness of these nanosheets, but shorter than that observed in bulk crystals.open6

Contributions of green infrastructure to enhancing urban resilience

© 2018, The Author(s). After briefly reviewing key resilience engineering perspectives and summarising some green infrastructure (GI) tools, we present the contributions that GI can make to enhancing urban resilience and maintaining critical system functionality across complex integrated social–ecological and technical systems. We then examine five key challenges for the effective implementation of GI that include (1) standards; (2) regulation; (3) socio-economic factors; (4) financeability; and (5) innovation. We highlight ways in which these challenges are being dealt with around the world, particularly through the use of approaches that are both context appropriate and socially inclusive. Although progress surmounting these challenges has been made, more needs to be done to ensure that GI approaches are inclusive and appropriate and feature equally alongside more traditional ‘grey’ infrastructure in the future of urban resilience planning. This research was undertaken for the Resilience Shift initiative to shift the approach to resilience in practice for critical infrastructure sectors. The programme aims to help practitioners involved in critical infrastructure to make decisions differently, contributing to a safer and better world

Surface Hardness Impairment of Quorum Sensing and Swarming for Pseudomonas aeruginosa

The importance of rhamnolipid to swarming of the bacterium Pseudomonas aeruginosa is well established. It is frequently, but not exclusively, observed that P. aeruginosa swarms in tendril patterns—formation of these tendrils requires rhamnolipid. We were interested to explain the impact of surface changes on P. aeruginosa swarm tendril development. Here we report that P. aeruginosa quorum sensing and rhamnolipid production is impaired when growing on harder semi-solid surfaces. P. aeruginosa wild-type swarms showed huge variation in tendril formation with small deviations to the “standard” swarm agar concentration of 0.5%. These macroscopic differences correlated with microscopic investigation of cells close to the advancing swarm edge using fluorescent gene reporters. Tendril swarms showed significant rhlA-gfp reporter expression right up to the advancing edge of swarming cells while swarms without tendrils (grown on harder agar) showed no rhlA-gfp reporter expression near the advancing edge. This difference in rhamnolipid gene expression can be explained by the necessity of quorum sensing for rhamnolipid production. We provide evidence that harder surfaces seem to limit induction of quorum sensing genes near the advancing swarm edge and these localized effects were sufficient to explain the lack of tendril formation on hard agar. We were unable to artificially stimulate rhamnolipid tendril formation with added acyl-homoserine lactone signals or increasing the carbon nutrients. This suggests that quorum sensing on surfaces is controlled in a manner that is not solely population dependent

Wnt, Hedgehog and Junctional Armadillo/β-Catenin Establish Planar Polarity in the Drosophila Embryo

To generate specialized structures, cells must obtain positional and directional information. In multi-cellular organisms, cells use the non-canonical Wnt or planar cell polarity (PCP) signaling pathway to establish directionality within a cell. In vertebrates, several Wnt molecules have been proposed as permissible polarity signals, but none has been shown to provide a directional cue. While PCP signaling components are conserved from human to fly, no PCP ligands have been reported in Drosophila. Here we report that in the epidermis of the Drosophila embryo two signaling molecules, Hedgehog (Hh) and Wingless (Wg or Wnt1), provide directional cues that induce the proper orientation of Actin-rich structures in the larval cuticle. We further find that proper polarity in the late embryo also involves the asymmetric distribution and phosphorylation of Armadillo (Arm or β-catenin) at the membrane and that interference with this Arm phosphorylation leads to polarity defects. Our results suggest new roles for Hh and Wg as instructive polarizing cues that help establish directionality within a cell sheet, and a new polarity-signaling role for the membrane fraction of the oncoprotein Arm

Caenorhabditis elegans Semi-Automated Liquid Screen Reveals a Specialized Role for the Chemotaxis Gene cheB2 in Pseudomonas aeruginosa Virulence

Pseudomonas aeruginosa is an opportunistic human pathogen that causes infections in a variety of animal and plant hosts. Caenorhabditis elegans is a simple model with which one can identify bacterial virulence genes. Previous studies with C. elegans have shown that depending on the growth medium, P. aeruginosa provokes different pathologies: slow or fast killing, lethal paralysis and red death. In this study, we developed a high-throughput semi-automated liquid-based assay such that an entire genome can readily be scanned for virulence genes in a short time period. We screened a 2,200-member STM mutant library generated in a cystic fibrosis airway P. aeruginosa isolate, TBCF10839. Twelve mutants were isolated each showing at least 70% attenuation in C. elegans killing. The selected mutants had insertions in regulatory genes, such as a histidine kinase sensor of two-component systems and a member of the AraC family, or in genes involved in adherence or chemotaxis. One mutant had an insertion in a cheB gene homologue, encoding a methylesterase involved in chemotaxis (CheB2). The cheB2 mutant was tested in a murine lung infection model and found to have a highly attenuated virulence. The cheB2 gene is part of the chemotactic gene cluster II, which was shown to be required for an optimal mobility in vitro. In P. aeruginosa, the main player in chemotaxis and mobility is the chemotactic gene cluster I, including cheB1. We show that, in contrast to the cheB2 mutant, a cheB1 mutant is not attenuated for virulence in C. elegans whereas in vitro motility and chemotaxis are severely impaired. We conclude that the virulence defect of the cheB2 mutant is not linked with a global motility defect but that instead the cheB2 gene is involved in a specific chemotactic response, which takes place during infection and is required for P. aeruginosa pathogenicity

Heavy burden of non-communicable diseases at early age and gender disparities in an adult population of Burkina Faso: world health survey

<p>Abstract</p> <p>Background</p> <p>WHO estimates suggest that age-specific death rates from non-communicable diseases are higher in sub-Saharan Africa than in high-income countries. The objectives of this study were to examine, in Burkina Faso, the prevalence of non-communicable disease symptoms by age, gender, socioeconomic group and setting (rural/urban), and to assess gender and socioeconomic inequalities in the prevalence of these symptoms.</p> <p>Methods</p> <p>We obtained data from the Burkina Faso World Health Survey, which was conducted in an adult population (18 years and over) with a high response rate (4822/4880 selected individuals). The survey used a multi-stage stratified random cluster sampling strategy to identify participants. The survey collected information on socio-demographic and economic characteristics, as well as data on symptoms of a variety of health conditions. Our study focused on joint disease, back pain, angina pectoris, and asthma. We estimated prevalence correcting for the sampling design. We used multiple Poisson regression to estimate associations between non-communicable disease symptoms, gender, socioeconomic status and setting.</p> <p>Results</p> <p>The overall crude prevalence and 95% confidence intervals (CI) were: 16.2% [13.5; 19.2] for joint disease, 24% [21.5; 26.6] for back pain, 17.9% [15.8; 20.2] for angina pectoris, and 11.6% [9.5; 14.2] for asthma. Consistent relationships between age and the prevalence of non-communicable disease symptoms were observed in both men and women from rural and urban settings. There was markedly high prevalence in all conditions studied, starting with young adults. Women presented higher prevalence rates of symptoms than men for all conditions: prevalence ratios and 95% CIs were 1.20 [1.01; 1.43] for joint disease, 1.42 [1.21; 1.66] for back pain, 1.68 [1.39; 2.04] for angina pectoris, and 1.28 [0.99; 1.65] for asthma. Housewives and unemployed women had the highest prevalence rates of non-communicable disease symptoms.</p> <p>Conclusions</p> <p>Our work suggests that social inequality extends into the distribution of non-communicable diseases among social groups and supports the thesis of a differential vulnerability in Burkinabè women. It raises the possibility of an abnormally high rate of premature morbidity that could manifest as a form of premature aging in the adult population. Increased prevention, screening and treatment are needed in Burkina Faso to address high prevalence and gender inequalities in non-communicable diseases.</p