151 research outputs found
Solution-processable 2,1,3-benzothiadiazole containing compound based on the novel 1-dodecyl-6-dodecoxynaphthyridine-2-one unit for organic field-effect transistors
Small molecule organic semiconductors have well-defined structures and can be used in place of polymers which often show batch-to-batch variation. Many different electron-rich donor and electron-deficient acceptor units have been used to design materials with reduced HOMO-LUMO gaps and improved mobilities. Here we introduce a novel acceptor unit, 1-dodecyl-6-dodecoxynaphthyridine-2-one. This acceptor unit has been used in the synthesis of two novel compounds, with thiophene and 2,1,3-benzothiadiazole (BT) cores. The BT-containing compound shows a narrower HOMO-LUMO gap, broad solid-state absorption and has been applied to organic field-effect transistors, showing a mobility of 0.022 cm2 V−1 s−1 after optimisation of devices using self-assembled monolayers
Effect of end group functionalisation of small molecules featuring the fluorene-thiophene-benzothiadiazole motif as emitters in solution-processed red and orange organic light-emitting diodes
A series of red fluorescent materials (compounds 1-4), which each contain the symmetric fluorene-thiophene-BT-thiophene-fluorene core, is presented along with their performance in solution-processed OLED devices. Extending the molecular conjugation through end-capping with additional fluorene units (compound 2), or through incorporation of donor functionalities (compounds 3 and 4) improves OLED performance relative to the parent compound 1. Notably, incorporating triphenylamine donor groups in compound 3 led to solution-processed OLED devices operating with a peak luminance of 2888 cd m −2 and a low turn-on voltage (3.6 V)
Nanoparticles of Cu2ZnSnS4 as performance enhancing additives for organic field-effect transistors
The addition of oleylamine coated Cu2ZnSnS4 (CZTS) nanoparticles to solutions of an organic semiconductor used to fabricate organic field-effect transistors (OFETs) has been investigated. The oligothiophene-based small molecule 5T-TTF and the polymer poly(3-hexylthiophene) (P3HT) were each applied in the transistors with various concentrations of CZTS (5-20%). Atomic force microscopy (AFM) was applied to characterise the surface morphology of the OFETs. The use of 5 and 10 wt% of the CZTS nanoparticles in 5T-TTF and P3HT solutions, respectively, appears to be a simple and effective way of improving OFET performance
Correction: Nanoparticles of Cu2ZnSnS4 as performance enhancing additives for organic field-effect transistors
Correction for 'Nanoparticles of Cu2ZnSnS4 as performance enhancing additives for organic field-effect transistors' by Punarja Kevin et al., J. Mater. Chem. C, 2016, DOI: 10.1039/c6tc01650b
To whom does the law speak? Canvassing a neglected picture of law’s interpretive field
Among the most common strategies underlying the so-called indeterminacy thesis is the following two-step argument: (1) that law is an interpretive practice, and that evidently legal actors more generally hold different (and competing) theories of meaning, which lead to disagreements as to what the law says (that is, as to what the law is); (2) and that, as there is no way to establish the prevalence of one particular theory of meaning over the other, indeterminacy is pervasive in law. In this paper I offer some reflections to resist this trend. In particular I claim that a proper understanding of law as an authoritative communicative enterprise sheds new light on the relation between the functioning of the law and our theories of interpretation, leading to what can be considered a neglected conclusion: the centrality of the linguistic criterion of meaning in our juridical interpretive practices. In the first part of the chapter I discuss speech-act theory in the study of law, assessing its relevance between alternative options. Then I tackle the ‘to whom does the law speak?’ question, highlighting the centrality of lay-people for our juridical practices. Lastly, I examine the consequences of this neglected fact for our interpretive theories
BRIGHT [C ii] AND DUST EMISSION IN THREE z > 6.6 QUASAR HOST GALAXIES OBSERVED BY ALMA
journal_title: The Astrophysical Journal article_type: paper copyright_information: © 2016. The American Astronomical Society. All rights reserved. date_received: 2015-06-16 date_accepted: 2015-11-23 date_epub: 2015-12-29journal_title: The Astrophysical Journal article_type: paper copyright_information: © 2016. The American Astronomical Society. All rights reserved. date_received: 2015-06-16 date_accepted: 2015-11-23 date_epub: 2015-12-29journal_title: The Astrophysical Journal article_type: paper copyright_information: © 2016. The American Astronomical Society. All rights reserved. date_received: 2015-06-16 date_accepted: 2015-11-23 date_epub: 2015-12-2
Climate Change, Migration, and Adaptation in the MENA Region
Climate change is a major source of concern in the Middle East and North Africa (MENA) region, and migration is often understood as one of several strategies used by households to respond to changes in climate and environmental conditions, including extreme weather events. Other coping and adaptation strategies include changing the household’s sources of livelihood, and selling assets or taking other emergency measures in cases of losses due to extreme weather events. Yet while there is a burgeoning literature on climate change and migration and other adaptation strategies worldwide, the evidence available for the MENA region remains limited, in part because of a lack of survey and other data. This chapter is based in large part on new data collected in 2011 in Algeria, Egypt, Morocco, Syria, and Yemen. Household surveys were implemented in two climate affected areas in each country. In addition, qualitative focus groups were also implemented in both urban and rural areas. Finally, complementary work was completed using existing data sources for Morocco and Yemen. The chapter provides a summary of some of the main findings from these various sources of data, focusing on household perceptions about climate change and extreme weather events, migration, other household coping and adaptation strategies, and government and community responses. Overall, households do perceive important change in the climate, and many have been affected by extreme weather events with resulting losses in income, crops, livestock, or fish catchment. The coping and adaptation strategies used by households to deal with shocks are diverse but limited, as are the community and government programs which could help households better cope with and adapt to climate change. In terms of migration, in the areas affected by climate change and weather shocks, the analysis suggests that climate factors may account for between one tenth and one fifth of the overall level of migration observed today, but this is likely to increase as climatic conditions continue to deteriorate. While migrants appreciate the opportunities that migration offer, their living conditions and ability to be well integrated in their areas of destination is far from being guaranteed
Predator-scale spatial analysis of intra-patch prey distribution reveals the energetic drivers of rorqual whale super-group formation
Animals are distributed relative to the resources they rely upon, often scaling in abundance relative to available resources. Yet, in heterogeneously distributed environments, describing resource availability at relevant spatial scales remains a challenge in ecology, inhibiting understanding of predator distribution and foraging decisions.
We investigated the foraging behaviour of two species of rorqual whales within spatially limited and numerically extraordinary super-aggregations in two oceans. We additionally described the lognormal distribution of prey data at species-specific spatial scales that matched the predator's unique lunge-feeding strategy.
Here we show that both humpback whales off South Africa's west coast and blue whales off the US west coast perform more lunges per unit time within these aggregations than when foraging individually, and that the biomass within gulp-sized parcels was on average higher and more tightly distributed within super-group-associated prey patches, facilitating greater energy intake per feeding event as well as increased feeding rates.
Prey analysis at predator-specific spatial scales revealed a stronger association of super-groups with patches containing relatively high geometric mean biomass and low geometric standard deviations than with arithmetic mean biomass, suggesting that the foraging decisions of rorqual whales may be more influenced by the distribution of high-biomass portions of a patch than total biomass. The hierarchical distribution of prey in spatially restricted, temporally transient, super-group-associated patches demonstrated high biomass and less variable distributions that facilitated what are likely near-minimum intervals between feeding events.
Combining increased biomass with increased foraging rates implied that overall intake rates of whales foraging within super-groups were approximately double those of whales foraging in other environments. Locating large, high-quality prey patches via the detection of aggregation hotspots may be an important aspect of rorqual whale foraging, one that may have been suppressed when population sizes were anthropogenically reduced in the 20th century to critical lows.Office of Naval Research,
Stanford University,
South African Department of the Environment, Forestry and Fisheries
National Science Foundation.http://wileyonlinelibrary.com/journal/fec2022-01-25hj2021Zoology and Entomolog
Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7
This is the third paper in a series aimed at finding reionization-era quasars with the combination of DESI Legacy imaging Surveys (DELS), the Pan-STARRS1 (PS1) Survey, and near-infrared imaging surveys, such as the UKIRT Hemisphere Survey (UHS), as well as the Wide-field Infrared Survey Explorer (WISE) mid-infrared survey. In this paper, we describe the updated quasar candidate selection procedure, report the discovery of 16 quasars at 6.4 z 6.9 from an area of ~13,020 deg2, and present the quasar luminosity function (QLF) at z ~ 6.7. The measured QLF follows in the magnitude range −27.6 5 that was found by previous works continues to z > 6, at a rate significantly faster than the average decline rate between z ~ 3 and 5. We measured quasar comoving emissivity at z ~ 6.7, which indicates that high-redshift quasars are highly unlikely to make a significant contribution to hydrogen reionization. The broad absorption line quasar fraction at z 6.5 is measured to be 22%. In addition, we also report the discovery of six additional quasars at z ~ 6 in the Appendix
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