High-Mobility Toolkit for Quantum Dot Films

Semiconductor colloidal quantum dots (CQDs) are being increasingly exploited in electronics, optoelectronics, and solar energy harvesting, using a variety of different architectures, mostly based on ordered 2D or 3D arrays of these nanostructures. A crucial issue for optimizing the performance of such devices is the ability to predict and tune the transport properties of these assemblies. In this work we provide general guidelines to precisely that effect, indicating specific materials, crystal structures, lattice arrangements, surface stoichiometries, and morphologies that favor high electron mobilities in these systems and, conversely, materials that will exhibit low mobilities if nanostructured. At the same time our results evidence a surprising independence of the film’s transport properties from those of the bulk material from which the dots are made, highlighting the crucial role of theoretical modeling to guide device design

Optical properties of nanocrystal films: blue shifted transitions as signature of strong coupling

We present a theoretical study at the atomistic level of the optical properties of semiconductor nanocrystal films. We investigate the dependence of the absorption coefficient on size, inter-dot separation, surface stoichiometry and morphology, temperature, position of the Fermi level and light polarization. Our results show that, counter-intuitively, huge blue shifts are expected in some intra-band transitions for strongly coupled arrays, in contrast with the predicted and observed red shift of the band gap absorption in such systems. Furthermore, we find that the energies of such transitions can be tuned within a range of several hundreds of meV, just by engineering the inter-dot separation in the film through the choice of appropriately sized capping ligands. Finally we discuss the application of this effect to nanocrystal-based intermediate-band solar cells

Effective Approach for an Order-of-Magnitude-Accurate Evaluation of the Electron Mobility in Colloidal Quantum Dot Films

Being able to estimate the electron mobility of colloidal quantum dot films is of great importance for determining their suitability to specific applications and would lead to huge savings in terms of time and resources that may otherwise be wasted trying to build and optimize a device whose transport characteristics can be predicted to be poor from the outset. This task is however complicated by the complexity of the system and the large number of parameters that can potentially affect the final result. Here, we derive a simple, fitting-parameter-free, order-of-magnitude-accurate expression to estimate the dark mobility of such 2D structures and validate it by applying it to real systems and comparing its predictions with those of other recently proposed approaches and with available experimental data. The results quantify the superiority of our expression to estimate mobilities in colloidal quantum dot films

Agreement and accuracy using the FIGO, ACOG and NICE cardiotocography interpretation guidelines.

INTRODUCTION: One of the limitations reported with cardiotocography (CTG) is the modest interobserver agreement observed in tracing interpretation. This study compared agreement, reliability and accuracy of CTG interpretation using the FIGO, ACOG and NICE guidelines. MATERIAL AND METHODS: A total of 151 tracings was evaluated by 27 clinicians from three centers where FIGO, ACOG and NICE guidelines were routinely used. Interobserver agreement was evaluated using the proportions of agreement (PA) and reliability with the kappa (k) statistic. The accuracy of tracings classified as "pathological/category III" was assessed for prediction of newborn acidemia. For all measures, 95% confidence intervals (95%CI) were calculated RESULTS: CTG classifications were more distributed with FIGO (9%, 52%, 39%) and NICE (30%, 33%, 37%) than with ACOG (13%, 81%, 6%). The category with the highest agreement was ACOG category II (PA=0.73 95%CI 0.70-76), and the ones with the lowest agreement were ACOG categories I and III. Reliability was significantly higher with FIGO (k=0.37, 95%CI 0.31-0.43), and NICE (k=0.33, 95%CI 0.28-0.39) than with ACOG (k= 0.15, 95%CI 0.10-0.21), however all represent only slight/fair reliability. FIGO and NICE showed a trend towards higher sensitivities in prediction of newborn acidemia (89% and 97% respectively) than ACOG (32%,), but the latter achieved a significantly higher specificity (95%) CONCLUSIONS: With ACOG guidelines there is high agreement in category II, low reliability, low sensitivity and high specificity in prediction of acidemia. With FIGO and NICE guidelines there is higher reliability, a trend towards higher sensitivity, and lower specificity in prediction of acidemia. This article is protected by copyright. All rights reserved

Variations of training load, monotony, and strain and dose-response relationships with maximal aerobic speed, maximal oxygen uptake, and isokinetic strength in professional soccer players

This study aimed to identify variations in weekly training load, training monotony, and training strain across a 10-week period (during both, pre- and in-season phases); and to analyze the dose-response relationships between training markers and maximal aerobic speed (MAS), maximal oxygen uptake, and isokinetic strength. Twenty-seven professional soccer players (24.9±3.5 years old) were monitored across the 10-week period using global positioning system units. Players were also tested for maximal aerobic speed, maximal oxygen uptake, and isokinetic strength before and after 10 weeks of training. Large positive correlations were found between sum of training load and extension peak torque in the right lower limb (r = 0.57, 90%CI[0.15;0.82]) and the ratio agonist/antagonist in the right lower limb (r = 0.51, [0.06;0.78]). It was observed that loading measures fluctuated across the period of the study and that the load was meaningfully associated with changes in the fitness status of players. However, those magnitudes of correlations were small-to-large, suggesting that variations in fitness level cannot be exclusively explained by the accumulated load and loading profile

Efficient, non-stochastic, Monte-Carlo-like-accurate method for the calculation of the temperature-dependent mobility in nanocrystal films

We present a new non-stochastic framework for the calculation of the temperature dependence of the mobility in nanocrystal films, that enables speed-ups of several orders of magnitude compared to conventional Monte Carlo approaches, while maintaining a similar accuracy. Our model identifies a new contribution to the reduction of the mobility with increasing temperature in these systems (conventionally attributed to interactions with phonons), that alone is sufficient to explain the observed experimental trend up to room temperature. Comparison of our results with the theoretical predictions of the hopping model and the observed temperature dependence of recent field-effect mobility measurements in nanocrystal films, provides the means to discriminate between band-like and hopping transport and a definitive answer to whether the former has been achieved in quantum dot films

Upper tropospheric ozone production from lightning NOx-impacted convection: Smoke ingestion case study from the DC3 campaign

©2015. American Geophysical Union. All Rights Reserved. As part of the Deep Convective Cloud and Chemistry (DC3) experiment, the National Science Foundation/National Center for Atmospheric Research (NCAR) Gulfstream-V (GV) and NASA DC-8 research aircraft probed the chemical composition of the inflow and outflow of two convective storms (north storm, NS, south storm, SS) originating in the Colorado region on 22 June 2012, a time when the High Park wildfire was active in the area. A wide range of trace species were measured on board both aircraft including biomass burning (BB) tracers hydrogen cyanide (HCN) and acetonitrile (ACN). Acrolein, a much shorter lived tracer for BB, was also quantified on the GV. The data demonstrated that the NS had ingested fresh smoke from the High Park fire and as a consequence had a higher VOC OH reactivity than the SS. The SS lofted aged fire tracers along with other boundary layer ozone precursors and was more impacted by lightning NOx (LNOx) than the NS. The NCAR master mechanism box model was initialized with measurements made in the outflow of the two storms. The NS and SS were predicted to produce 11 and 14ppbv of O3, respectively, downwind of the storm over 2days. Sensitivity tests revealed that the ozone production potential of the SS was highly dependent on LNOx. Normalized excess mixing ratios, ΔX/ΔCO, for HCN and ACN were determined in both the fire plume and the storm outflow and found to be 7.0±0.5 and 2.3±0.5pptvppbv-1, respectively, and 1.4±0.3pptvppbv-1 for acrolein in the outflow only

Synthesis and Anti-Mycobacterium tuberculosis Activity of Imidazo[2,1-b][1,3]oxazine Derivatives against Multidrug-Resistant Strains

The emergence of multidrug-resistant strains of M. tuberculosis has raised concerns due to the greater difficulties in patient treatment and higher mortality rates. Herein, we revisited the 2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazine scaffold and identified potent new carbamate derivatives having MIC90 values of 0.18–1.63 μM against Mtb H37Rv. Compounds 47–49, 51–53, and 55 exhibited remarkable activity against a panel of clinical isolates, displaying MIC90 values below 0.5 μM. In Mtb-infected macrophages, several compounds demonstrated a 1-log greater reduction in mycobacterial burden than rifampicin and pretomanid. The compounds tested did not exhibit significant cytotoxicity against three cell lines or any toxicity to Galleria mellonella. Furthermore, the imidazo[2,1-b][1,3]oxazine derivatives did not show substantial activity against other bacteria or fungi. Finally, molecular docking studies revealed that the new compounds could interact with the deazaflavin-dependent nitroreductase (Ddn) in a similar manner to pretomanid. Collectively, our findings highlight the chemical universe of imidazo[2,1-b][1,3]oxazines and their promising potential against MDR-TB

An audio-visual system for object-based audio : from recording to listening

Object-based audio is an emerging representation for audio content, where content is represented in a reproduction format-agnostic way and, thus, produced once for consumption on many different kinds of devices. This affords new opportunities for immersive, personalized, and interactive listening experiences. This paper introduces an end-to-end object-based spatial audio pipeline, from sound recording to listening. A high-level system architecture is proposed, which includes novel audiovisual interfaces to support object-based capture and listenertracked rendering, and incorporates a proposed component for objectification, that is, recording content directly into an object-based form. Text-based and extensible metadata enable communication between the system components. An open architecture for object rendering is also proposed. The system’s capabilities are evaluated in two parts. First, listener-tracked reproduction of metadata automatically estimated from two moving talkers is evaluated using an objective binaural localization model. Second, object-based scene capture with audio extracted using blind source separation (to remix between two talkers) and beamforming (to remix a recording of a jazz group) is evaluate