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Air pollution characterized by fine particulate matter (PM2.5) frequently has occurred in China, and has posed threats to human health. The physiochemical characteristics of airborne PM2.5 have been extensively studied, but its bacterial structures and functions have not yet been well studied. Herein, we focused on the structural characteristics and functional implications of airborne bacteria under different pollution levels in Beijing and Shanghai. The α- and β-diversities showed no obvious difference in two cities (p > 0.05). The dominant phyla Proteobacteria, Firmicutes, and Actinobacteria with total abundance of over 92% were found in all PM2.5 samples. The results of weighted unifrac non-metric multidimensional scaling (NMDS) suggested that air pollution was no obviously correlated with bacterial community but dispersed disorderly. Furthermore, canonical correlation analysis (CCA) and permutation test indicated that NH 4 + , SO 4 2 - , and wind speed were the key factors that associated with airborne bacterial community structure. Chemical components of particulate matter played more important role in structuring bacterial community than meteorological conditions based on the result of partial CCA. In addition, the annotation of metabolic pathway suggested that the predominant genus Pseudomonas was obviously correlated with disease infections. Several dominant species might contribute to organic degradation, nitrogen cycles, and ice-nuclei activities in environments. Overall, this work enhanced our understanding of functions of airborne bacteria and highlighted their potential role in atmospheric chemical progresses. [ABSTRACT FROM AUTHOR]

Bioaugmentation with exogenously functional microbes is a widely used technology in bioengineering and environmental remediation. Generally, the colonization of inoculated bacteria is considered to be the determining factor in technical success. However, increasing reports have shown that bioaugmentation was still effective when the colonization of inoculated bacteria was unsuccessful. Here, an augmentation study with iron-reducing bacteria (IRB, Shewanella decolorationis S12) was conducted in Fe(II)-poor sediments to elucidate the role of exogenously inoculated bacteria for bioaugmentation performance. The results showed that a sufficient amount of IRB inputs enhanced the iron reduction in bioaugmented sediments, even though the exogenous IRB did not colonize after the beginning of the experiment (less than 1% at day 3). The iron reduction function responded to stimulation of the indigenous IRB community such as Clostridium, Cupriavidus, Fervidicella, and Acinetobacter, which comprised less than 1% in the initial sediments. Moreover, compared with microbial community in control sediment, more positive correlations between OTUs were observed for that in S12-added sediments upon network analysis. The pH and oxidation-reduction potential of sediment were found to be the predominant factors shaping the iron-reducing microbial communities. It meant that exogenous IRB successfully trigged functional community via altering microenvironment by the inoculated bacteria. Overall, this study provides a new insight into the understanding of the role of single strain addition in iron-reducing bioaugmentation. [ABSTRACT FROM AUTHOR]

We propose that the Li anode can be protected by a Cu coating via the technique of magnetron sputtering. Cu has high electrical conductivity, mechanical strength, and chemical stability. Li deposition on Cu coating with a porous structure disperses the local current density and produces a uniform Li-ion flux, greatly suppressing growth of Li dendrites and the layer prevents Li from directly contacting electrolyte while ensures Li-ion transport. The symmetric battery with the Cu-coated Li anode lasting for 140 h presents stable Li deposition/dissolution and improved polarization. The full Li–S battery adopting this modified anode exhibits well-improved cycling stability and capacity retention. It delivers an initial discharge specific capacity of 1148 mAh/g and obtains 526 mAh/g after 300 cycles with high Coulombic efficiency of 99.6% at 0.5 C (1 C = 1675 mAh/g), while the traditional Li–S battery only obtains 490 mAh/g after 200 cycles. Scanning electron microscopy images of the cycled Cu-coated Li anode presents favorable integrity. Electrochemical impedance spectra, cyclic voltammogram, and charge-discharge profiles were investigated to consolidate the function of the Cu coating. This simple and facile strategy provides an approach to protect the metal electrode applied in other metal batteries. [ABSTRACT FROM AUTHOR]

Conductive carbon films (CF1) were made of carbonized filter paper and modified with titanium(Ti) and aluminum(Al) thin films deposited on their surface by radiofrequency magnetron sputtering to prepare carbon films CF2 and CF3 as functional interlayers for lithium-sulfur (Li-S) batteries, with the cathode material (S-AC) synthesized with elemental sulfur (S) and activated carbon (AC). Material characterization and electrochemical performance tests indicated that batteries (S/AC/CF1, S/AC/CF2, and S/AC/CF3), with carbon films inserted between the cathode and separator, showed improved electrochemical properties than S/AC without interlayers. In particular, S/AC/CF2 and S/AC/CF3 delivered initial discharge-specific capacities of 1257 and 1394 mAh/g, respectively, and reversible capacities of 836 and 889 mAh/g were obtained, with the Coulombic efficiency over 99%, after 100 cycles at the current rate of 0.5 C. Experiments showed that Ti and Al tiny particles plated on the surface of carbon interlayers can facilitate superior performance for Li-S batteries. [ABSTRACT FROM AUTHOR]

Porous carbon has high specific area and total pore volume but weak interaction with dissolved polysulfides. Conductive polar metal compound has strong chemical adsorption of polysulfides but difficult to attain high porosity to encapsulate sulfur series. Instead of efforts on the cathode, we prepared a composite made up of titanium nitride and three-dimensional micro-/mesoporous carbon by a facile and economic way. This composite was coated on the commercial Celgard separator as a polysulfide interceptor to enhance the performances of lithium-sulfur battery. The strategy exerts the synergetic merits of porosity, chemical adsorption, physical interception, and benign conductivity. The hierarchical carbon possesses a high specific surface area of 1571 m2/g and total pore volume of 1.56 cm3/g with the pore size centered at 1.27 and 5.30 nm. TiN can immobilize sulfur intermediates by strong chemical interaction. In addition, excellent electrical conductivity of TiN facilitates redox kinetics. The pure sulfur cathode with the modified separator delivers high initial capacity of 1130 mAh/g at 1 C (1 C = 1675 mAh/g) and retains 500 mAh/g after 400 cycles, demonstrating superior cycling stability, rate capabilities. Discharge-charge profiles, electrochemical impedance spectrum, and cyclic voltammetry curves of batteries were investigated to support the prominent electrochemistry of the material. Further analysis and observation on the modified separator disassembled from the coin cells after cycling were conducted to probe the evolution and reaction mechanism of the coating. [ABSTRACT FROM AUTHOR]

The two-dimensional (2D) transition-metal dichalcogenides (TMDs) field effect transistor (FET) with in-plane heterojunction contacts between the semiconducting 2H phase (as channel) and the metallic 1T or semi-metallic 1T′ phase (as electrode) has received much recent attention because it has significantly reduced contact resistance and enhanced gate tunability and thus improved device performance. However, the underlying mechanism of its good conductivity remains open. We systematically explore for the first time the contact properties of the monolayer (ML) 2H MX2 (MoS2, WS2, MoSe2, WSe2, MoTe2) FET with their 1T′ phase as electrode by using ab initio quantum transport simulations. We find that the metal induced gap states (MIGS) at the interface penetrate the Schottky barrier and bridge the electrodes and the conduction/valence band of the channel, thereby forming a lower and tunable effective Schottky barrier height (ESBH) and causing an equivalent Ohmic contact under the appropriate gate voltage. Our study provides a new insight into the observed reduced contact resistance with the 1T′ phase as electrode and is instructive for further experiment. [ABSTRACT FROM AUTHOR]

The non-uniformity of microwave sterilization usually causes incomplete inactivation of microorganism (especially foodborne pathogens) and potential food safety issue. Detecting the non-uniformity of load distribution using hyperspectral imaging (HSI) (400-1050 nm) in tandem with multivariate analysis was investigated and infrared (IR) thermal imaging technique was used to assist the evaluation. The best simplified model of least-squares support vector machines (LS-SVM) obtained based on ten optimal wavelengths showed an R2p of 0.905, RMSEP of 0.404 log CFU/mL and RPD of 2.62, while the analysis of temperatures detected by IR thermal camera showed that the temperatures of mid-way along each edge were obviously higher than the center, and heating time of microwave had a significant effect on mean temperature (p < 0.01) and temperature coefficient of variation (COV) values (p < 0.01). Moreover, the visualization of L. monocytogenes load distribution was acquired by transferring the quantitative model of LS-SVM to each pixel in the image at different heating times, with the results being well consistent with those of temperature distribution by IR thermal camera. Therefore HSI technique could be used to monitor the non-uniformity of microwave sterilization processing. [ABSTRACT FROM AUTHOR]

Moore’s law is approaching its physical limit. Tunneling field-effect transistors (TFETs) based on 2D materials provide a possible scheme to extend Moore’s lawdown to the sub-10-nm region owing to the electrostatic integrity and absence of dangling bonds in 2D materials. We report an ab initio quantum transport study on the device performance of monolayer (ML) black phosphorene (BP)TFETs in the sub-10-nm scale (6-10 nm). Under the optimal schemes, the ML BP TFETs show excellent device performance along the armchair transport direction.The on-state current, delay time, and power dissipation of the optimal sub-10-nm ML BP TFETs significantly surpass the latest International Technology Roadmap for Semiconductors (ITRS) requirements for high-performance devices. The subthreshold swings are 56-100 mV/dec, which are much lower than those of their Schottky barrier and metal oxide semiconductor field-effect transistor counterparts. [ABSTRACT FROM AUTHOR]

A mesoporous carbon (MC) is prepared by the method of hard-template. Cathode materials (S/MC) for Li-S battery were synthesized. Properties of S, MC, and S/MC were characterized by BET, XRD, Raman, HRTEM, and FESEM. Electrochemical performances of the batteries were determined by AC impedance, cyclic voltammetry, and constant-current charging and discharging. Experiments show that MC, prepared with mass ratio CaCO3/PVA = 1/1.5, is the most suitable for Li-S battery. Thereby, the battery shows initial specific capacity of 1383.6 mAh/g and 881.6 mAh/g after 100 cycles, and the Coulombic efficiencies are both over 98% after 100 cycles at the current rate of 0.5 and 1 C. [ABSTRACT FROM AUTHOR]

Semiconducting monolayer (ML) blue phosphorene (BlueP) shares similar stability with ML black phosphorene (BP), and it has recently been grown on an Au surface. Potential ML BlueP devices often require direct contact with metal to enable the injection of carriers. Using ab initio electronic structure calculations and quantum transport simulations, for the first time, we perform a systematic study of the interfacial properties of ML BlueP in contact with metals spanning a wide work function range in a field effect transistor (FET) configuration. ML BlueP has undergone metallization owing to strong interaction with five metals. There is a strong Fermi level pinning (FLP) in the ML BlueP FETs due to the metal-induced gap states (MIGS) with a pinning factor of 0.42. ML BlueP forms n-type Schottky contact with Sc, Ag, and Pt electrodes with electron Schottky barrier heights (SBHs) of 0.22, 0.22, and 0.80 eV, respectively, and p-type Schottky contact with Au and Pd electrodes with hole SBHs of 0.61 and 0.79 eV, respectively. The MIGS are eliminated by inserting graphene between ML BlueP and the metal electrode, accompanied by a transition from a strong FLP to a weak FLP. Our study not only provides insight into the ML BlueP-metal interfaces, but also helps in the design of ML BlueP devices. [ABSTRACT FROM AUTHOR]

Phosphorene has attracted much attention recently as an alternative channel material in nanoscale electronic and optoelectronic devices due to its high carrier mobility and tunable direct bandgap. Compared with monolayer (ML) phosphorene, few-layer (FL) phosphorene is easier to prepare, is more stable in experiments, and is expected to form a smaller Schottky barrier height (SBH) at the phosphorene-metal interface. Using ab initio electronic structure calculations and quantum transport simulations, we perform a systematic study of the interfacial properties of three-layer (3L) phosphorene field effect transistors (FETs) contacted with several common metals (Al, Ag, Au, Cu, Ti, Cr, Ni, and Pd) for the first time. The SBHs obtained in the vertical direction from projecting the band structures of the 3L phosphorene-metal systems to the left bilayer (2L) phosphorenes are comparable with those obtained in the lateral direction from the quantum transport simulations for 2L phosphorene FETs. The quantum transport simulations for the 3L phosphorene FETs show that 3L phosphorene forms n-type Schottky contacts with electron SBHs of 0.16 and 0.28 eV in the lateral direction, when Ag and Cu are used as electrodes, respectively, and p-type Schottky contacts with hole SBHs of 0.05, 0.11, 0.20, 0.30, 0.30, and 0.31 eV in the lateral direction when Cr, Pd, Ni, Ti, Al, and Au are used as electrodes, respectively. The calculated polarity and SBHs of the 3L phosphorene FETs are generally in agreement with the available experiments. [ABSTRACT FROM AUTHOR]

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of 5-aminoimidazole-4-carboxamide-1-β- d-ribofuranoside (AICA riboside) and its active metabolite 5-aminoimidazole-4-carboxamide-1-β- d-ribofuranotide (AICA ribotide) in mice plasma. Adenosine monophosphate was chosen as an internal standard, and plasma was deproteinized by adding 14% perchloric acid, and then, the resulting supernatant was diluted with water to decrease matrix effect. A 10 μL aliquot of the solution was injected into the LC-MS/MS system, and separation was achieved on a Gemini C-Phenyl column with a mobile phase composed of 0.1% formic acid (v/v) and methanol. A triple quadrupole mass spectrometer with an electrospray turbo ion source operating in multiple reaction monitoring (MRM) positive ion mode was used as detector. The precursor-product ion pairs for MRM were m/ z 259.2 → 110.1 and 259.2 → 242.1 for AICA riboside, 339.1 → 110.1 and 339.1 → 322.1 for AICA ribotide, and 348.3 → 136.0 and 348.3 → 119.1 for the internal standard, respectively. The total analytical run time was 10 min. The proposed method was linear over the range 0.01-10 μg/mL for AICA riboside and 0.01-5 μg/mL for AICA ribotide. The lower limit of quantification (LLOQ) was 10 ng/mL for both AICA riboside and AICA ribotide. The sensitivity, accuracy, and precision of this method were within acceptable limits during the validation period. The method was successfully applied to investigate the pharmacokinetics characteristics of AICA riboside and AICA ribotide in mice. [ABSTRACT FROM AUTHOR]

Developing regionally applicable models for timely mapping of rice yield potential still faces challenges like the poor accuracy of yield prediction at early stages, and the scale mismatch between ground samples and satellite image pixels. Here, we explored the potential of using high-resolution multispectral images and texture features derived from unmanned aerial system (UAS) to fill these gaps. Rice field experiments were carried out in eastern China during 2017, 2018, and 2020 to acquire UAS (eBee-SQ) and satellite (Sentinel-2) images at jointing stage as well as the rice final yield. High spatial-resolution (HSR, 0.1 m) eBee-SQ images were used to extract both textures and vegetation indices (VIs), the resampled medium spatial-resolution (MSR, 20 m) eBee-SQ and Sentinel-2 images were only used to extract VIs. Firstly, using experimental data from 2017 and 2018, five kinds of yield prediction models at jointing stage were developed with: [ⅰ] VIs derived from MSR Sentinel-2 images and linear regression (LR) (least-RMSE = 1.68 t ha−1), [ⅰi] VIs derived from MSR eBee-SQ images and LR (least-RMSE = 1.482 t ha−1), [ⅱi] VIs derived from HSR eBee-SQ images and LR (least-RMSE = 1.371 t ha−1), [iv] VI-texture mixed indices derived from HSR eBee-SQ images and LR (least-RMSE = 1.082 t ha−1), and [v] random forest (RF) regression combining VIs and textures derived from HSR eBee-SQ images (least-RMSE = 0.997 t ha−1). These results showed that yield prediction models developed by both MSR and HSR eBee-SQ data performed better than by MSR Sentinel-2 data. Secondly, using optimal models derived from HSR eBee-SQ data and in-season HSR eBee-SQ data, different farm-scale HSR yield potential maps were generated. These yield maps were processed to Sentinel-2 resolution (20 m) to relate with Sentinel-2 VI for building integrated yield prediction models (IPMs) based on linear and quadratic regression. IPMs were then used to map town-scale rice yield potential by importing Sentinel-2 VI from jointing stage, and were compared with simple yield prediction model (SPM) that directly used Sentinel-2 VI. The independent validation results using yield data collected in 2020 suggested that all of the IPMs were more accurate (RMSE = 0.64 – 0.74 t ha−1) than the SPM (RMSE = 0.96 t ha−1). Besides, IPMs involving eBee-SQ derived textures and VIs showed higher accuracy in mapping yield potential than IPM involving eBee-SQ derived VI only. Overall, this study provides a novel approach to accurately mapping the regional rice yield potential through the integration of satellite and UAS data. • Combining VI and texture improved yield prediction accuracy at rice jointing stage. • Textures from red-edge band were more conducive to yield prediction in RF model. • UAS-predicted yield map was upscaled and correlated with satellite VI to build IPM. • IPM improved accuracy for mapping town-level yield potential compared with SPM. • UAS served as an intermediate source to fill gaps between ground and satellite data. [ABSTRACT FROM AUTHOR]

• The appropriate hyperspectral range for wheat DASF retrieval is 710–760 nm. • The DASF k-b model was proposed to estimate b and k by RAGDD and BRF. • The canopy structure effect could be corrected by CSC k-b model. • CSC k-b model was superior to CSC g-NIR and VIs model in LNC and LCC estimation. • The estimation accuracy at non-vertical VZAs (−30, −45°) outperformed nadir VZA. Canopy scattering coefficient (CSC) is the ratio of bidirectional reflectance factor (BRF) to directional area scattering coefficient (DASF), and has been successfully applied to correct the effect of canopy structure. The key to calculate CSC is to calculate DASF, which is determined by the intercept b and slope k of the linear relationship between BRF and BR F λ Ω ω λ (the ratio of hyperspectral BRF in certain view direction to leaf albedo (ω λ). However, due to the limitation of multispectral bands, how to accurately calculate crop DASF during the whole growth period using multispectral UAV data is still an urgent problem to be solved. In this study, wheat canopy multi-angular (0°, −30°, −45°) datasets including near-ground hyperspectral data, UAV multispectral data, and PROSAIL simulation data were obtained for three consecutive years. The DASF k-b model was proposed to estimate b and k based on multispectral sensors by relative accumulated growing degree days (RAGDD) and BRF. The previously developed DASF g-NIR model and vegetation index (VI) model were compared with DASF k-b model under different view angles (VZAs), to evaluate their performances in correcting canopy structural effect, estimating leaf nitrogen content (LNC) and leaf chlorophyll content (LCC) based on generalized additive model (GAM). The results showed that the hyperspectral band range suitable for estimating wheat DASF was 710–760 nm. Parameter b decreased with increased N application rates, and activated first and then inhibited with increased RAGDD; the tendency of k, DASF Hy were opposite. Compared with CSC g-NIR (calculated from DASF g-NIR model) and VIs, CSC k-b (calculated from DASF k-b model) had the best correction effect on canopy structure under different VZAs. The estimation accuracy of LNC and LCC using CSC k-b was improved compared with CSC g-NIR and VIs, with RRMSE values of 9.2% and 7.0%, respectively, and the recommended VZA was −45° for both models. [ABSTRACT FROM AUTHOR]