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Maize leaf spot occurs worldwide and affects maize production. Maize can be infected by several pathogens causing leaf spot, such as Bipolaris zeicola, Bipolaris maydis, Curvularia species, Alternaria species, etc. In the current study, 30 Epicoccum isolates recovered from symptomatic maize leaves were identified based on morphological characteristics, pathogenicity, and multilocus sequence analyses of nuLSU, ITS, tub2, and rpb2. These maize isolates were grouped into five Epicoccum species, including E. nigrum, E. layuense, E. sorghinum, E. latusicollum, and E. pneumoniae. Pathogenicity tests showed that all five Epicoccum species could produce small ellipse- and spindle-shaped spots on maize leaves. The lesion center was grayish yellow to dark gray and surrounded by a chlorotic area. Furthermore, the Epicoccum isolates exhibited high pathogenicity to 20 main maize varieties of Heilongjiang Province but showed different sensitivities to the commonly used fungicides carbendazim and tebuconazole. In addition, these Epicoccum isolates showed different production capacity of pectinase, cellulase, protease, amylase, laccase, and gelatinase, but all showed high lipase activity. This is the first report globally of E. layuense, E. latusicollum, and E. pneumoniae as causal agents of maize leaf spot. E. pneumoniae was first reported as a plant pathogen.

Reverse water gas shift (RWGS) reaction is a crucial process in CO2 utilization. Herein, Ni- and NiCe-containing hexagonal mesoporous silica (Ni-HMS and NiCe-HMS) catalysts were synthesized using an in-situ one-pot method and applied for RWGS reaction. At certain reaction temperatures 500-750 °C, Ni-HMS samples displayed a higher selectivity to the preferable CO than that of conventionally impregnated Ni/HMS catalyst. This could be originated from the smaller NiO nanoparticles over Ni-HMS catalyst. NiCe-HMS exhibited higher activity compared to Ni-HMS. The catalysts were characterized by means of TEM, XPS, XRD, H2-TPR, CO2-TPD, EPR and N2 adsorption-desortion technology. It was found that introduction of Ce created high concentration of oxygen vacancies, served as the active site for activating CO2. Also, this work analyzed the effect of the H2/CO2 molar ratio on the best NiCe-HMS. When reaction gas H2/CO2 molar ratio was 4 significantly decreased the selectivity to CO at low temperature, but triggered a higher CO2 conversion which is close to the equilibrium.

Photocatalytic conversion of CO2 and H2O into CH4 is an intriguing approach to achieve solar energy utilization and CO2 conversion, yet remains challenging in conversion efficiency. In this study, we present a synthesis of defected TiO2 nanocrystal with oxygen vacancies (Vo) by a facile Ru doping-induced strategy under hydrothermal condition. The synergistic effect of Ru and oxygen vacancies contributed to the enhanced photocatalytic reduction of CO2 toward CH4. Oxygen vacancies and doped Ru not only can synergistically promote the separation of photogenerated carriers, but also promote the CO2 adsorption, thus enhancing the photocatalytic activities. The optimal Ru-doped TiO2 (denoted as 1% Ru-TiO2-x) exhibited a remarkable enhanced photocatalytic performance with a CH4 yield of 31.63 μmol·g–1·h–1, which is significantly higher than Ru-TiO2 and TiO2-x counterparts. This study systematically investigates the multiple roles of Ru in CO2 reduction and provides new insights for the construction of metal oxide photocatalysts with oxygen vacancies by simple doping of metal ions.

Dual probe is capable of simultaneously measuring electric and magnetic fields in the same position, given that perfectly symmetric design is realized on the transmission paths connecting the detection loop and the probe outputs. For general application, a calibration method for the asymmetric probing in near-field measurement with the dual probe is presented, in order to deal with the failure of the traditional calibration due to the asymmetric transmissions in both paths. The asymmetric probing measurement is modeled, and then the proposed calibration to eliminate the asymmetry is further derived based on two independent measurements at two directions (0° and 90°) between the probe and the microstrip line providing a known electromagnetic field at the surface. The calibration method is demonstrated with two kinds of dual probes of different coupling structure. The proposed calibration is validated by introducing the asymmetry to the probing process in the measurement of the standing wave along a conductor-backed coplanar waveguide transmission line.

Nitrogenous octadecylamine (ODA) self-assembled multilayers (SAMs) are prepared as passivation layers by the vapor-phase process for amorphous InSnZnO (ITZO) thin-film transistors (TFTs). The vapor-phase proposed ODA SAMs show excellent properties as a barrier against the atmosphere and serve as an effective nitrogen doping (N doping) source. After the self-assembled process, the distribution of the oxygen vacancies is modified by N-doping in the channel of the ITZO TFTs, wherefore the ITZO TFTs with ODA SAMs demonstrate an improvement of electrical properties. In addition, the oxygen and water adsorption/desorption reactions at the back channel are suppressed by the atmosphere isolation and N-doping effect, leading to an improvement of the positive bias stability. These results indicate that the nitrogenous ODA SAMs can be likely passivation layers for high-performance oxide TFT devices.

This paper develops an active magnetic near field probe (H‐field probe) by using a four‐layer printed circuit board (PCB) technique. Two‐turn detection structure and a low noise amplifier are used to improve probe's frequency response. The two‐turn detection structure can maximize the use of PCB stack resources, and a 14.5 dB gain amplifier can increase signal output capability. The probe can then be used for electromagnetic compatibility (EMC) test from 150 kHz to 3 GHz. Compared with traditional active shielded‐loop H‐field probe (TAHP) with loop area of 500 μm2, the frequency response of the proposed probe can improve 20 dB at 0.5 GHz. Different from the method of comparing the sensitivity of the probe only through the frequency response, this paper measures and analyzes the real sensitivity of the probing device composed of the proposed probe. Under the condition of the same receiver parameter setting, the sensitivity at 0.5 GHz is increased by 11.7 dB compared with commercial passive probing device and 20.2 dB at 0.5 GHz compared with the probing device with TAHP device. It reaches −32.4 dB μA. In addition, the proposed probe has acceptable spatial resolution of 1.28 mm at 1 GHz, which is more suitable for printed circuit board level EMI analysis.

Photo-chemical conversion of CO2 into solar fuels by photocatalysts is a promising and sustainable strategy in response to the ever-increasing environmental problems and imminent energy crisis. However, it is unavoidably impeded by the insufficient active site, undesirable inert charge transfer and fast recombination of photogenerated charge carriers on semiconductor photocatalysts. In this work, all these challenges are overcome by construction of a novel defect-engineered Z-scheme hybrid photocatalyst, which is comprised of three-dimensional (3D) BiOBr nanoflowers assembled by nanosheets with abundant oxygen vacancies (BiOBr-VO) and two-dimensional (2D) HNb3O8 nanosheets (HNb3O8 NS). The special 3D-2D architecture structure is beneficial to preventing photocatalyst stacking and providing more active sites, and the introduced oxygen vacancies not only broaden the light absorption range but also enhance the electrical conductivity. More importantly, the constructed Z-scheme photocatalytic system could accelerate the charge carriers transfer and separation. As a result, the optimal BiOBr-VO/HNb3O8 NS (50%-BiOBr-VO/HNb3O8 NS) shows a high CO production yield of 164.6 μmol·g−1 with the selectivity achieves to 98.7% in a mild gas-solid system using water as electron donors. Moreover, the BiOBr-VO/HNb3O8 NS photocatalyst keeps high photocatalytic activity after five cycles under the identical experimental conditions, demonstrating its excellent long-term durability. This work provided an original strategy to design a new hybrid structure photocatalyst involved VOs, thus guiding a new way to further enhance CO2 reduction activity of photocatalyst.

Photocatalytic reduction of CO2 toward eight-electron CH4 product with simultaneously high conversion efficiency and selectivity remains great challenging owing to the sluggish charge separation and transfer kinetics and lack of active sites for the adsorption and activation of reactants. Herein, a defective TiO2 nanosheet photocatalyst simultaneously equipped with AuCu alloy co-catalyst and oxygen vacancies (AuCu-TiO2-x NSs) was rationally designed and fabricated for the selective conversion of CO2 into CH4. The experimental results demonstrated that the AuCu alloy co-catalyst not only effectively promotes the separation of photogenerated electron-hole pairs but also acts as synergistic active sites for the reduction of CO2. The oxygen vacancies in TiO2 contribute to the separation of charge carriers and, more importantly, promote the oxidation of H2O, thus providing rich protons to promote the deep reduction of CO2 to CH4. Consequently, the optimal AuCu-TiO2-x nanosheets (NSs) photocatalyst achieves a CO2 reduction selectivity toward CH4 up to 90.55%, significantly higher than those of TiO2-x NSs (31.82%), Au-TiO2-x NSs (38.74%), and Cu-TiO2-x NSs (66.11%). Furthermore, the CH4 evolution rate over the AuCu-TiO2-x NSs reaches 22.47 μmol·g-1·h-1, which is nearly twice that of AuCu-TiO2 NSs (12.10 μmol·g-1·h-1). This research presents a unique insight into the design and synthesis of photocatalyst with oxygen vacancies and alloy metals as the co-catalyst for the highly selective deep reduction of CO2.

Due to the multiple electron and proton transfer processes involved, the photogenerated charges are easily recombined during the photocatalytic reduction of CO

Due to the high stability of the N

This letter demonstrates unipolar p-type MoS2 field-effect transistors (p-FETs). The p-FETs are fabricated using high work function Pt as the contact electrode and p-type MoS 2 film as the active channel. The p-FETs, with a channel length of 1- $\mu $ m, show an output current of $-10~\mu $ A/ $\mu $ m with a drain voltage of −1 V. The Pt electrode, formed by slow electron-beam evaporation, shows a contact barrier height of 0.13 eV. In comparison, a faster deposition rate results in a larger resistance and a higher contact barrier of the Pt electrode. Raman characterization provides certain support for the improved contact interface of the slowly deposited Pt electrode, which may be an essential factor in improving current drive.

In this study, we demonstrated self-powered fast-response ultraviolet (UV) detection based on a highly-rectifying graphene/GaN Schottky contact. The device was fabricated by mechanically transferring a monolayer graphene onto lightly-doped GaN and showed excellent Schottky behaviors, including a high rectification ratio ( $> 10^{8}$ ), a close-to-unity ideality factor and a relatively high Schottky barrier height (1.01 eV). At zero bias, the graphene/GaN Schottky photodiodes exhibited a strong photovoltaic response to UV illumination with a competitively short rise/decay time of 221/ $546~\mu \text{s}$ . A trap-associated photoconductive mechanism started to dominate the device’s response when its bias went beyond −1 V, which could be identified from the suddenly increased responsivity and response time.

In this article, the degradation behavior of the commercial 1.2-kV SiC power MOSFETs was investigated under repetitive power-cycling stress, and defect analysis based on low-frequency noise (LFN) was carried out. The experimental results show that increasing power-cycling stress results in a forward shift of threshold voltage and increasing ON-resistance. Meanwhile, the drain-to-source current significantly decreases with the increase of the cycles. Furthermore, the gate–source leakage current of the device became larger and the blocking characteristics deteriorated after 10-k cycles. The negative shift of the gate-capacitance versus gate-voltage curve was analyzed. Trap characterization was performed by using the LFN method, and it was found that the trap density of the device increased 5.47 times after 10-k cycles. The physical mechanism could be attributed to electrically active trapped charges generated at the SiC/SiO2 interface during power-cycling stress. This article may be helpful for degradation detection and fault analysis of SiC power MOSFETs in the electronic system.

As COVID-19 spread worldwide, many major grain-producing countries have adopted measures to restrict their grain exports; food security has aroused great concern from various parties. How to improve grain production has become one of the most important issues facing all countries. However, crop diseases are a difficult problem for many farmers so it is important to master the severity of crop diseases timely and accurately to help staff take further intervention measures to minimize plants being further infected. In this paper, a restructured residual dense network was proposed for tomato leaf disease identification; this hybrid deep learning model combines the advantages of deep residual networks and dense networks, which can reduce the number of training process parameters to improve calculation accuracy as well as enhance the flow of information and gradients. The original RDN model was first used in image super resolution, so we need to restructure the network architecture for classification tasks through adjusted input image features and hyper parameters. Experimental results show that this model can achieve a top-1 average identification accuracy of 95% on the Tomato test dataset in AI Challenger 2018 datasets, which verifies its satisfactory performance. The restructured residual dense network model can obtain significant improvements over most of the state-of-the-art models in crop leaf identification, as well as requiring less computation to achieve high performance.

As the COVID-19 spread worldwide, countries around the world are actively taking measures to fight against the epidemic. To prevent the spread of it, a high sensitivity and efficient method for COVID-19 detection is necessary. By analyzing the COVID-19 chest X-ray images, a combination method of image regrouping and ResNet-SVM was proposed in this study. The lung region was segmented from the original chest X-ray images and divided into small pieces, and then the small pieces of lung region were regrouped into a regular image randomly. Furthermore the regrouped images were fed into the deep residual encoder block for feature extraction. Finally the extracted features were as input into support vector machine for recognition. The visual attention was introduced in the novel method, which paid more attention to the features of COVID-19 without the interference of shapes, rib and other related noises. The experimental results showed that the proposed method achieved 93% accuracy without large number of training data, outperformed the existing COVID-19 detection models.

Due to the low-carbon economy requirement in large-scale industrial applications, exploration of active, robust, resourceful, low-cost and efficient oxygen evolution reaction (OER) electrocatalysts is urgently needed. In this work, we report a Fe–N co-doped cobalt selenide nanosheet array (Fe–N–CoSe2) on nickel foam (NF) as a highly efficient OER electrocatalyst via an anion and cation co-doping strategy using a metal–organic framework (MOF) as the precursor. The nanosheet arrays grown on NF without an additional binder are not only beneficial for accelerating the charge transfer, but also for suppressing electrocatalyst shedding. Furthermore, the nanosheet structure constructed using nanograins could promote electrolyte penetration and gas diffusion and increase the active sites. More importantly, the Fe and N element doping can further provide additional active sites, regulate the electronic structure and boost the OER kinetics. In view of the abovementioned points, the as-prepared Fe–N–CoSe2 electrocatalyst exhibits outstanding OER performance and long-term durability. It affords a current density of 50 mA cm−2 at a small overpotential of 270 mV with a Tafel slope of 62.7 mV dec−1, and the Fe–N–CoSe2 electrocatalyst has only a small attenuation of 1.9% after a 100 h constant test at 100 mA cm−2 in alkaline solution, which is superior to the commercial RuO2 electrode. These results offer a potential approach for the preparation of effective and robust OER electrocatalysts as substitutes to replace the expensive commercial electrocatalysts based on element doping.

The paper presents the design and fabrication of lateral-field-excited (LFE) resonators based on 42° Y-cut single-crystal LiTaO3 (LT) on silicon dioxide (SiO2). A simple coplanar top electrode is defined to excite the bulk acoustic wave modes in the suspended LT/SiO2 structure, and the fabrication process that only involves two lithography steps is more simplified compared to that of commercial film bulk acoustic wave resonators. For a model structure consisting of LT(670 nm)/SiO2 (1500 nm) thin film, two types of acoustic modes are both piezoelectrically active in the LT film: the first one is the thickness-shear mode with a resonance frequency of 2.46 GHz, an electromechanical coupling ( $k_{eff}^{2}$ ) of 1.4%, a high quality factor ( ${Q}$ ) of 1690, and the second one corresponds to longitudinal mode with a resonance frequency of 4.39 GHz, ${k} _{eff}^{2}$ of 1.2%, a high ${Q}$ of 1590, which is among the highest reported for piezoelectric MEMS resonators operating at this frequency range. The excellent performance would enable application scenarios including high-resolution sensors, low-phase-noise oscillators, and low-loss, high selectivity filters in the sub-6 GHz range for the fifth-generation (5G) wireless communication.

An oxygen-doped, hollow, porous NiCoP nanocage (O-NiCoP Cages) electrocatalyst was synthesized derived from Ni-Co Prussian blue analogs. O-NiCoP Cages exhibited an overpotential of 310 mV at 10 mA cm-2 and a Tafel slope of 84 mV dec-1, significantly higher than that of undoped NiCoP nanocages, and also better than that of RuO2 and several reported phosphide electrocatalysts. This work provides a new strategy for the design of highly efficient oxygen evolution reaction (OER) electrocatalysts based on hollow, nanostructured and heteroatom-doped metal phosphides.

The paper presents the design and fabrication of lateral-field-excited (LFE) resonators based on 42° Y-cut single-crystal LiTaO3 (LT) on silicon dioxide (SiO2). A simple coplanar top electrode is defined to excite the bulk acoustic wave modes in the suspended LT/SiO2 structure, and the fabrication process that only involves two lithography steps is more simplified compared to that of commercial film bulk acoustic wave resonators. For a model structure consisting of LT(670 nm)/SiO2 (1500 nm) thin film, two types of acoustic modes are both piezoelectrically active in the LT film: the first one is the thickness-shear mode with a resonance frequency of 2.46 GHz, an electromechanical coupling ( $k_{eff}^{2}$ ) of 1.4%, a high quality factor ( ${Q}$ ) of 1690, and the second one corresponds to longitudinal mode with a resonance frequency of 4.39 GHz, ${k} _{eff}^{2}$ of 1.2%, a high ${Q}$ of 1590, which is among the highest reported for piezoelectric MEMS resonators operating at this frequency range. The excellent performance would enable application scenarios including high-resolution sensors, low-phase-noise oscillators, and low-loss, high selectivity filters in the sub-6 GHz range for the fifth-generation (5G) wireless communication.

In practice, early detection of disease is of high importance to practical value, corresponding measures can be taken at the early stage of plant disease. However, in the early stage of disease or when a rare disease occurs, there are limited training samples in practice, which makes machine learning especially deep learning models hardly work well while the stronger representative ability needs large-scale training data. To solve this problem, a fine grained-GAN based grape leaf spot identification method was proposed for local spot area image data augmentation to the generated local spot area images which were added and fed them into deep learning models for training to further strengthen the generalization ability of the classification models, which can effectively improve the accuracy and robustness of the prediction. Including 500 early-stage grape leaf spot images every category were fed into the proposed fine grained-GAN for local spot area data augmentation, 1000 local spot area sub images every category were generated in this study. The improved faster R-CNN was integrated in fine grained-GAN as local spot area detector. After that, the segmented sub-images and generated sub-images were mixed as training data input into the deep learning models, while the original segmented sub-images were used for testing. Experimental results showed that the proposed method had achieved higher identification accuracy on five state-of-art deep learning models; especially ResNet-50 had got 96.27% accuracy, which obtained significant improvements than other data augmentation methods and verified its satisfactory performance. This is of great practical significance for rare diseases or limited training samples.

This paper presents a brief review of experimental and theoretical studies on a three-dimensional heterostructure consisting of vertical carbon nanotubes (CNTs) connected perpendicularly to a graphene layer. This structure can serve as a potential building block for an all-carbon network in energy storage devices and on-chip interconnects. The review highlights reported works on the fabrication and characterization of such a heterostructure, with focus on the effect of the CNT-graphene interface on electrical conduction. While a direct comparison between experiment and theory is not possible at this time, a brief survey of theoretical efforts based on atomic cluster models nonetheless reveals important knowledge about the electronic transport properties of this all-carbon heterostructure.

An ultralow- ${k}$ dielectric using structured pores to reduce interconnect propagation delay is demonstrated. By using a carbon nanotube (CNT) template, porous oxide with vertical cylindrical pores is formed on the Si3N4 etch-stop layer and successfully integrated with the copper damascene process. The resulting dielectric is anisotropic with an interlayer dielectric constant of k = 1.97 and an intralayer dielectric constant of k = 1.75 at a porosity of 65%. Compared with the conventional porous material with randomly arranged spherical pores, a much higher elastic modulus of 15.7 GPa is achieved to allow the chemical mechanical polish process at a porosity of 65%.

Changes in land use and forest planting have led to substantial changes in soil fertility and leaf litter input. The effects of mixed planting on the leaf litter decomposition rate in contrasting soil nutrient conditions are poorly understood. To elucidate the effects of litter composition and soil fertility on litter decomposition, we conducted a field litterbag-decomposition experiment with single (Pinus massoniana Lamb. or Quercus variabilis Bl.) and mixed (P. massoniana and Q. variabilis) litter treatments on soils of three nutrient levels (high, medium, and low). During the 3-year decomposition, at each decomposition stage and soil nutrient level, the mass-loss rate (MLR) was higher in mixed-litter than in the two single-litter treatments, with the exception of Q. variabilis, which recorded a higher MLR at 724 d in medium and high soil substrates. Between the two single-litter treatments, the MLR of Q. variabilis litter was higher than that of the P. massoniana litter; the MLR of the component litter of P. massoniana and Q. variabilis was higher than that of the corresponding two single-litter treatments. The k values over the 3-year-experiment period increased with the soil nutrient level for all litter treatments, as did microbial biomass carbon and nitrogen content. These findings suggest that mixed planting and high level of soil nutrient can accelerate litter decomposition.

A stable, earth-abundant, reusable cobalt-based heterogeneous catalyst is developed for the oxidative esterification of alcohols under ambient conditions, featuring broad substrate scope, providing good to excellent product yields. This protocol enables easy recyclability of the catalyst, measured up to five times without significant loss of efficiency. The active sites of Co-N-Si/AC are proposed to be Co-N species.

Photocatalytic reduction of CO

Photocatalytic conversion of CO

In this letter, a compact model for charge and drain current in molybdenum disulfide (MoS2) field-effect transistors (FETs) is developed, which is valid from ballistic to quasi-ballistic to drift-diffusion electronic transport regimes. Considering the influence of trap charges in MoS2 transistors, a physical-based and analytical charge model is derived. Based on the virtual source model which applies to both ballistic and quasi-ballistic transports, the carrier number density and current expressions are combined to yield the current-voltage (I-V) characteristics. Furthermore, the presented model is validated by experimental data as well as recently reported simulations for MoS2 FETs with different gate lengths. It shows that our model is accurate, straight-forward, scalable and compatible for short- and long-channel devices.

To allow air-gaps with a large void size within a metal spacing, we propose the use of h-BN as an air-gap capping layer, which suspends the inter-metal dielectric in a CMOS back-end-of-line (BEOL) process. The fabrication process, based on the transfer of h-BN to seal air-gap regions, is discussed, including the use of Al2O3 on h-BN film for mechanical stability, and the consequence of thermal expansion coefficient mismatch in the materials introduced. A capacitance reduction of up to 50% is achieved through the large void size in the h-BN-capped air-gap technology. Demonstration of the proposed air-gap technology at $\mu $ m dimension for top-level metalization is presented. The compromise on Young’s modulus for a low effective- $\kappa $ is measured and benchmarked against typical values in low- $\kappa $ technology.

Alkylquinolines are ubiquitous in functional products. However, the direct and selective alkylation of quinolines has to date remained a challenge. Herein, by developing a new catalyst composing of cobalt oxides supported on N-Si-doped titanium dioxide (CoOx/N-Si-TiO2), we present, for the first time, its application toward hydrogen transfer-mediated dual β-alkylations of 2-alkylquinolines with various aldehydes. The developed chemistry allows a direct access to a wide array of 2,3-dialkylquinolines in conjunction with the features of good substrate and functional group compatibility, high regio and chemoselectivity, the use of naturally abundant and reusable heterogeneous cobalt catalyst, and the generation of H2O as the by-product, which has demonstrated the potential in direct functionalization of multiple heteroaryl C H bonds by the combination of heterogeneous catalyst design with reductive dearomatization as an activating mode of N-heteroarenes.