Quantum Rod Emission Coupled to Plasmonic Lattice Resonances: A Collective Directional Source of Polarized Light

We demonstrate that an array of optical antennas may render a thin layer of randomly oriented semiconductor nanocrystals into an enhanced and highly directional source of polarized light. The array sustains collective plasmonic lattice resonances which are in spectral overlap with the emission of the nanocrystals over narrow angular regions. Consequently, different photon energies of visible light are enhanced and beamed into definite directions.Comment: 4 pages, 3 figure

Validation of the TROPOspheric Monitoring Instrument (TROPOMI) surface UV radiation product

The TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor (S5P) satellite was launched on 13 October 2017 to provide the atmospheric composition for atmosphere and climate research. The S5P is a Sun-synchronous polar-orbiting satellite providing global daily coverage. The TROPOMI swath is 2600 km wide, and the ground resolution for most data products is 7:23:5 km2 (5:63:5 km2 since 6 August 2019) at nadir. The Finnish Meteorological Institute (FMI) is responsible for the development of the TROPOMI UV algorithm and the processing of the TROPOMI surface ultraviolet (UV) radiation product which includes 36 UV parameters in total. Ground-based data from 25 sites located in arctic, subarctic, temperate, equatorial and Antarctic areas were used for validation of the TROPOMI overpass irradiance at 305, 310, 324 and 380 nm, overpass erythemally weighted dose rate/UV index, and erythemally weighted daily dose for the period from 1 January 2018 to 31 August 2019. The validation results showed that for most sites 60 % 80% of TROPOMI data was within 20% of ground-based data for snow-free surface conditions. The median relative differences to ground-based measurements of TROPOMI snow-free surface daily doses were within 10% and 5% at two-Thirds and at half of the sites, respectively. At several sites more than 90% of cloud-free TROPOMI data was within 20% of groundbased measurements. Generally median relative differences between TROPOMI data and ground-based measurements were a little biased towards negative values (i.e. satellite data ground-based measurement), but at high latitudes where non-homogeneous topography and albedo or snow conditions occurred, the negative bias was exceptionally high: from 30% to 65 %. Positive biases of 10 % 15% were also found for mountainous sites due to challenging topography. The TROPOMI surface UV radiation product includes quality flags to detect increased uncertainties in the data due to heterogeneous surface albedo and rough terrain, which can be used to filter the data retrieved under challenging conditions

Surface Doping Quantum Dots with Chemically Active Native Ligands: Controlling Valence without Ligand Exchange

One remaining challenge in the field of colloidal semiconductor nanocrystal quantum dots is learning to control the degree of functionalization or valence per nanocrystal. Current quantum dot surface modification strategies rely heavily on ligand exchange, which consists of replacing the nanocrystal\u27s native ligands with carboxylate- or amine-terminated thiols, usually added in excess. Removing the nanocrystal\u27s native ligands can cause etching and introduce surface defects, thus affecting the nanocrystal\u27s optical properties. More importantly, ligand exchange methods fail to control the extent of surface modification or number of functional groups introduced per nanocrystal. Here, we report a fundamentally new surface ligand modification or doping approach aimed at controlling the degree of functionalization or valence per nanocrystal while retaining the nanocrystal\u27s original colloidal and photostability. We show that surface-doped quantum dots capped with chemically active native ligands can be prepared directly from a mixture of ligands with similar chain lengths. Specifically, vinyl and azide-terminated carboxylic acid ligands survive the high temperatures needed for nanocrystal synthesis. The ratio between chemically active and inactive-terminated ligands is maintained on the nanocrystal surface, allowing to control the extent of surface modification by straightforward organic reactions. Using a combination of optical and structural characterization tools, including IR and 2D NMR, we show that carboxylates bind in a bidentate chelate fashion, forming a single monolayer of ligands that are perpendicular to the nanocrystal surface. Moreover, we show that mixtures of ligands with similar chain lengths homogeneously distribute themselves on the nanocrystal surface. We expect this new surface doping approach will be widely applicable to other nanocrystal compositions and morphologies, as well as to many specific applications in biology and materials science

Molecular Chemistry to the Fore: New Insights into the Fascinating World of Photoactive Colloidal Semiconductor Nanocrystals

Colloidal semiconductor nanocrystals possess unique properties that are unmatched by other chromophores such as organic dyes or transition-metal complexes. These versatile building blocks have generated much scientific interest and found applications in bioimaging, tracking, lighting, lasing, photovoltaics, photocatalysis, thermoelectrics, and spintronics. Despite these advances, important challenges remain, notably how to produce semiconductor nanostructures with predetermined architecture, how to produce metastable semiconductor nanostructures that are hard to isolate by conventional syntheses, and how to control the degree of surface loading or valence per nanocrystal. Molecular chemists are very familiar with these issues and can use their expertise to help solve these challenges. In this Perspective, we present our group\u27s recent work on bottom-up molecular control of nanoscale composition and morphology, low-temperature photochemical routes to semiconductor heterostructures and metastable phases, solar-to-chemical energy conversion with semiconductor-based photocatalysts, and controlled surface modification of colloidal semiconductors that bypasses ligand exchange

Publisher Correction:Network inference from glycoproteomics data reveals new reactions in the IgG glycosylation pathway

Correction to: Nature Communications (2017) 8:1231. doi:10.1038/s41467-017-01525-

Genetic fine mapping and genomic annotation defines causal mechanisms at type 2 diabetes susceptibility loci.

We performed fine mapping of 39 established type 2 diabetes (T2D) loci in 27,206 cases and 57,574 controls of European ancestry. We identified 49 distinct association signals at these loci, including five mapping in or near KCNQ1. 'Credible sets' of the variants most likely to drive each distinct signal mapped predominantly to noncoding sequence, implying that association with T2D is mediated through gene regulation. Credible set variants were enriched for overlap with FOXA2 chromatin immunoprecipitation binding sites in human islet and liver cells, including at MTNR1B, where fine mapping implicated rs10830963 as driving T2D association. We confirmed that the T2D risk allele for this SNP increases FOXA2-bound enhancer activity in islet- and liver-derived cells. We observed allele-specific differences in NEUROD1 binding in islet-derived cells, consistent with evidence that the T2D risk allele increases islet MTNR1B expression. Our study demonstrates how integration of genetic and genomic information can define molecular mechanisms through which variants underlying association signals exert their effects on disease

Genome-wide physical activity interactions in adiposity. A meta-analysis of 200,452 adults

Physical activity (PA) may modify the genetic effects that give rise to increased risk of obesity. To identify adiposity loci whose effects are modified by PA, we performed genome-wide interaction meta-analyses of BMI and BMI-adjusted waist circumference and waist-hip ratio from up to 200,452 adults of European (n = 180,423) or other ancestry (n = 20,029). We standardized PA by categorizing it into a dichotomous variable where, on average, 23% of participants were categorized as inactive and 77% as physically active. While we replicate the interaction with PA for the strongest known obesity-risk locus in the FTO gene, of which the effect is attenuated by similar to 30% in physically active individuals compared to inactive individuals, we do not identify additional loci that are sensitive to PA. In additional genome-wide meta-analyses adjusting for PA and interaction with PA, we identify 11 novel adiposity loci, suggesting that accounting for PA or other environmental factors that contribute to variation in adiposity may facilitate gene discovery.Peer reviewe

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