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• We report numerical results for light reflection from the top of a Rayleigh scattering spherical atmosphere over a dark surface. • We account for polarization of light and height-dependent single scattering albedo. • We report single and multiple scattering data separately to support validation and development of RT codes for spherical atmospheres. We report numerical results for polarized light reflection from the top of a Rayleigh scattering spherical atmosphere with height-dependent single scattering albedo over a dark surface. Michael Mishchenko considered this scenario back in the 1990's, for a plane-parallel atmosphere of unit optical thickness (OT = 1), for which radiance errors arising from neglecting polarization reaches their highest values. To further extend Mishchenko's results, we consider a value of OT = 0.25, for which the effect of atmospheric curvature is pronounced. New results are generated using three state-of-the art radiative transfer (RT) codes. These are: the MYSTIC and MCSSA models, which simulate light scattering in a true-spherical atmosphere using Monte Carlo methods; and the discrete ordinate code VLIDORT, operating with a new multiple-scatter spherical correction designed to deliver reasonable approximations to spherical-medium scattering. In this work, we report results for both single and multiple scattering; this will help to support the validation of existing and future polarized spherical RT codes, especially those using approximative methods to deal with sphericity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tailorable thiophenes are introduced into polymers symmetrically or asymmetrically. • The polymers bearing asymmetric π bridges overperform their symmetric counterparts. • Asymmetric π bridges engineering is confirmed to be a promising strategy for donors. In comparison with the common-used electron donor (D)-electron acceptor (A) type symmetric polymers with regular structures, their asymmetric counterparts have received much less attention and seldom been applied in polymer solar cells. Since the precise modulation of π bridge can significantly influence the photoelectric properties of D-A type polymers, π bridges of tailorable thiophenes are introduced into benzodithiophene (BDT)-benzodithiophene-4,8-dione (BDD) copolymers in both symmetric and asymmetric patterns. Together with the halogen substituent of fluorine or chlorine on BDT, four polymer donors are designed and synthesized. As expected, PTB2T-F and PTB2T-Cl with the asymmetric π bridges of thiophene and hexyl-bithiophene exhibit better planarity, stronger intermolecular interaction and higher hole mobility than P2TB2T-F and P2TB2T-Cl with the symmetric π bridges of hexyl-bithiophene. The more suitable phase separation and optimized nanomorphology is determined by the reasonable miscibility between asymmetric polymer and acceptor, which is evaluated by Flory-Huggins interaction, contributing to the extremely higher performance than that of symmetric counterpart. Moreover, paired with IT-4F as the acceptor, PTB2T-F affords better device performances than the reference BDT-BDD polymer PM6 with the symmetry π bridge of thiophene. These results demonstrate that the precise modulation of asymmetric π bridges is a promising strategy to construct high-efficiency D-A type polymer donors. [ABSTRACT FROM AUTHOR]

With the significant impact of the COVID-19 pandemic, understanding the sources of COVID-19 infection is crucial for developing effective public health strategies to control the spread of the disease. Chinese immigrants in Canada represent a population for which no study had previously been conducted to investigate the sources of COVID-19 infection. This study aimed to address this knowledge gap by examining the prevalence of various sources of COVID-19 within the Chinese immigrant community and identifying potential risk factors associated with each source. An online cross-sectional survey was conducted in early 2023, which included questions on five possible sources of COVID-19 infection: family, social gatherings, workplace, public places, or unknown. A total of 591 responses were received, of which 488 eligible responses were included in the analysis. 56.4% of the survey respondents were female, 45.0% had a university degree (or higher), and 19.4% of the participants were 65 years of age or older. Among the 226 individuals who contracted COVID-19, the most commonly reported source of infection was family members (29.2%), followed by public places (27.4%), and social gatherings (16.4%). Additionally, 16.4% of the respondents were uncertain where they had contracted the virus, and 10.6% of the respondents contracted COVID-19 from their workplace. A large majority of participants were able to identify the source of their COVID-19 infection, with results suggesting that individuals are at the highest risk for contraction of COVID-19 from infected family members. Our findings can inform public health efforts to control the spread of COVID-19 in Canada. [ABSTRACT FROM AUTHOR]

It is widely recommended that enhanced efficiency nitrogen fertilizers (EENFs; urease inhibitors, nitrification inhibitors, urease and nitrification inhibitors combined, coated controlled-release urea) be applied to croplands to improve N use efficiency and crop yield via regulating N transformations. However, EENFs may inevitably affect soil C dynamics for the coupled relationship between soil carbon (C) and N biogeochemical cycles. Yet, a comprehensive assessment of the effects of EENFs on soil C dynamics is lacking. Here, we conducted a global meta-analysis using 67 publications to assess the overall effects of EENFs on soil CH 4 production, CO 2 emission, organic C (SOC) content, dissolved organic C (DOC) content, microbial biomass C (MBC) content under different environmental and management conditions (climate conditions, soil properties and fertilizer management practices). Our results showed that on average, compared to conventional N fertilizer, EENFs with the same amount of N fertilizer have a non-significant impact on CH 4 emission, which further depended on environmental and management conditions. Best scenarios for CH 4 reduction included: paddy field (25.8%), urease inhibitor (26.9%) and medium N application rate (150–300 kgN ha−1; 23.6%), mainly due to the decreased stimulation of NH 4 + on CH 4 production; acid soil (33.7%), which was attributed to the enhanced methanotrophic communities' activities. The positive effect was also amplified by the increased mean annual precipitation and soil clay content that facilitated CH 4 production. Contrarily, EENFs significantly reduced CO 2 emission by 9.3%. The greater reduction was observed for the conditions producing more CO 2 after fertilization, i.e. field experiment, alkaline soils, low soil inorganic N content and high N application rate (≥300 kgN ha−1). Nitrification inhibitors and coated N fertilizer were the best available options as they can reduce inorganic C dissolution in calcareous soil and SOC mineralization, respectively. Besides, EENFs application did not significantly alter SOC, DOC and MBC contents. Our findings highlighted the role of EENFs played in decreasing soil C emission in agroecosystems. [Display omitted] • Global use of EENFs did not significantly affect SOC, DOC, MBC contents. • EENFs succeed in reducing CO 2 emission (9.3%) rather than CH 4 emission. • EENFs provide a viable solution for decreasing soil C emissions in global agroecosystems. [ABSTRACT FROM AUTHOR]

Dopant-free, electron donor (D)–acceptor (A) type, polymeric hole-transporting materials (HTMs) possess excellent film formability and hole transport properties, which ensure high efficiency, stability, and reproducibility to the PVSCs. Compared with benzothiadiazole (BT), benzotriazole (BTA) was less incorporated into polymeric HTMs. Herein, two indacenodithieno[3,2-b]thiophene (IDTT)-BTA copolymers BT-T and BT-TT containing different π-bridge of thiophene and thienothiophene, are synthesized and studied. BT-T bearing thiophene π-bridge presents decent coplanarity, higher hole mobility, and better interface morphology than its sister polymer BT-TT. The PVSC with dopant-free BT-T displayed a peak power conversion efficiency (PCE) of 17.1% and remained above 85% of its initial PCE for more than 30 days at ambient conditions. In view of the rare report on the BTA-based polymeric HTMs, this work will cast lights on further exploration of high-efficiency D-A polymeric HTMs. Two indacenodithieno[3,2-b]thiophene-benzotriazole copolymers BT-T and BT-TT containing π-bridge of thiophene and thienothiophene, respectively, are developed as dopant-free hole-transporting materials. [Display omitted] • Two polymers containing benzotriazole are developed as hole-transporting materials. • π-bridge of thiophene endows BT-T higher coplanarity and hole mobility. • BT-T shows superior hole transport properties to BT-TT with thienothiophene π-bridge. • The perovskite solar cells based on dopant-free BT-T display an efficiency of 17.1%. [ABSTRACT FROM AUTHOR]

In this paper, an indirect flow pattern recognition method based on time-frequency analysis and neural networks is proposed to investigate the flow patterns in the narrow rectangular channel under heating and non-inertial conditions. Firstly, the adaptive optimal kernel algorithm is utilized to analyze on the typical pressure signal and convert it into time-frequency spectrograms. Then based on the concept of transfer learning strategy, convolutional neural networks are applied as feature extractors to classify flow patterns by the spectrogram images. The proposed method is verified by the visualized flow boiling experiment data. The results show that the adaptive time-frequency algorithm can effectively reflect the characteristics of different flow pattern signals, and several chosen neural network models show high recognition accuracy after training. Among them, VGG-16 network with small convolution kernels and strong transferability has the highest recognition rate. In addition, the network based on data of static conditions remains identifying more than 75% spectrograms of rolling conditions, exhibiting the generalization ability of the method under different flow conditions. • Combining traditional time-frequency signal processing method with latest deep learning strategy. • Flow pattern recognition in the narrow channel under heating and non-inertial conditions. • Verified by the visualized flow boiling experiment data and shows high recognition accuracy. • Network has generalization ability under different flow conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Granulation of PD granular sludge was achieved with the glycerol as carbon source. • The glycerol-fed PDGS showed superior settleability with efficient nitrite yield. • The proteins in T-EPS played key roles in the formation of PDGS. • The PN, PS and living cells distributed uniformly in PDGS to maintain bioactivity. • Saccharibacteria was speculated to be mainly responsible for the granulation. Granular sludge is considered as a promising technology for wastewater treatment owing to the high biomass retention and excellent settleability. In this study, the formation and underlying mechanisms of granular sludge for stable and efficient nitrite accumulation in glycerol-driven partial denitrification (PD) reactors were investigated. The PD granular sludge (PDGS) was successfully formed with developing and mature stages. The mature PDGS exhibited superior settleability (mean particle size: 468.1 μm, and SVI 5 :16.4 mL/g SS), and high microbial activity (VSS/SS: 0.80–0.92). The nitrite was stably and efficiently accumulated with an average nitrate-to nitrite transformation ratio of 87.3%. Morphological analysis showed that the mature granules were dominated by cocci and exhibited compact structure with few inorganic components. The proteins (i.e. tyrosine, tryptophan and aromatic protein-like substances) in tightly-bound extracellular polymeric substances (EPS) were expected to play critical roles in the granulation process in view of their good correlation with particle size variation. The EPS contents (mainly polysaccharides and proteins) and living cells were distributed throughout the granule, suggesting the overall high stability and bioactivity of formed PDGS. Moreover, the glycerol-driven PD reactor caused the evident evolution of microbial structure, and the significant enrichment of Saccharibacteria was expected to be responsible for the granulation process, which was increased to 66.6% in the matured sludge. This study confirmed the feasibility and superior performance of PDGS fed with glycerol. [ABSTRACT FROM AUTHOR]

WarpX is a general purpose electromagnetic particle-in-cell code that was originally designed to run on many-core CPU architectures. We describe the strategy, based on the AMReX library, followed to allow WarpX to use the GPU-accelerated nodes on OLCF's Summit supercomputer, a strategy we believe will extend to the upcoming machines Frontier and Aurora. We summarize the challenges encountered, lessons learned, and give current performance results on a series of relevant benchmark problems. • Optimization of memory usage can be as important as optimization of run time. • Memory Arenas aid in getting performance on GPU hardware with common programming patterns. • Fusing kernels in communication routines is key to work around kernel launch latency. • Exploiting the cache hierarchy on V100 GPUs leads to large performance increases. [ABSTRACT FROM AUTHOR]