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The electric fields generated by lightning discharges propagate upward and couple with the lower ionosphere, triggering various mesospheric optical emissions. The potential role of local terrain in modulating the lightning-generated electric fields in the lower ionosphere remains poorly understood. To investigate the effect of mountain terrain on the lightning-generated electric fields at high altitudes (70–85 km), a two-dimensional (2D) finite-difference time-domain (FDTD) simulation model was developed. The simplified mountain is parameterized by its height, width, and horizontal distance from the lightning channel. Simulation results show that mountain terrain significantly influences the lightning-driven electric field waveforms in the initiation region of sprite halos. Increased mountain height leads to greater attenuation of the high-altitude electric field amplitudes, thereby suppressing sprite halos initiation. The shielding effect of mountain width on the electric fields is less pronounced than that of mountain height, and it stabilizes when the width exceeds 40 km. When the horizontal distance between the mountain and lightning channel is less than 40 km, the electric field attenuation increases significantly with decreasing distance. The attenuation effect gradually weakens beyond a distance of 40 km, yet the electric field waveforms exhibit considerable fluctuations due to the reflection process.

In this study, a specific and simple method based on the dual priming oligonucleotide (DPO) system was developed to simultaneously detect transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), porcine rotavirus A (PRV-A), porcine delta coronavirus (PDCoV), and swine acute diarrhea syndrome coronavirus (SADS-CoV), associated with the major enteric RNA viruses in pigs. The DPO system-based multiplex RT-PCR method simplified the primer design and did not require optimization of the annealing temperature. Specificity analysis revealed that the method could specifically detect TGEV, PEDV, PRV-A, PDCoV, and SADS-CoV without any cross-amplification of other circulating swine viruses. The limit of detection of the method was as low as 103–104 copies/μL plasmid of each virus. The method also had good repeatability, and obvious results were seen in three repeat experiments with an interval of 45 days. This optimized multiplex RT-PCR method was used to evaluate 181 clinical swine samples that were collected from four provinces of China between September 2016 and August 2018. The results showed that the positive detection rates of PEDV, PDCoV, SADS-CoV, PRV-A, and TGEV were 30.94% (56/181), 17.67% (32/181), 11.6% (21/181), 9.39% (17/181), and 0.55% (1/181), respectively. Mixed infection of two or more viruses was also common. The DPO system-based multiplex RT-PCR could be a useful tool for detecting enteric virus infections. This method has the advantages of easy operation, low cost, high detection efficiency, and short running time for early diagnosis in clinical cases.

Lightning-induced voltages (LIVs) computation is crucial for lightning protection of power systems and equipment, yet the effect of complex terrain on LIVs remains not fully evaluated. This study establishes a three-dimensional finite-difference time-domain model to investigate the LIVs over Gaussian-shaped mountainous terrain, considering different lightning strike locations. Simulation results show that the influence of Gaussian-shaped mountains on LIVs is directly related to the lightning strike location. Compared with the flat ground scenario, the LIVs’ amplitude can increase by approximately 56% when lightning strikes the mountain top. However, for lightning strikes to the ground adjacent to the mountain, the LIVs’ amplitude is attenuated to varying degrees due to the shielding effect of the mountain. Additionally, the influences of line configuration, as well as mountain height and width on the LIVs, are evaluated.

To meet the demand for real-time oxygen concentration monitoring in flight tests of aircraft fuel tank inerting systems, this paper reviews three mainstream airborne oxygen concentration measurement technologies: the electrochemical method, TDLAS, and the fluorescence quenching method. It also elaborates on their working principles and technical characteristics. Accuracy verification tests were carried out on typical existing domestic testing equipment. Their measurement performance under different pressure conditions was then compared and analyzed. The results show that the measurement accuracy of all three types of equipment can reach within ±0.3% under normal pressure, while the equipment based on TDLAS and fluorescence quenching principles performs better in low-pressure environments. Furthermore, considering the application scenarios of flight tests, the equipment performance was comprehensively evaluated from multiple aspects. The advantages and disadvantages of each type of system were summarized, and improvement directions, such as modular design and gas path protection optimization, were proposed. The research results can provide technical support and serve as a reference for the subsequent development of airborne oxygen concentration monitoring systems.

A one-pot Ugi–azide reaction followed by intramolecular Cu-free azide–alkyne cycloaddition generates a polycyclic scaffold 7 bearing polycyclic triazole, tetrazole, and benzodiazepine rings. This method could be extended for obtaining a more complicated scaffold 8 containing a piperazinone ring.

Background For cereal crop breeding, it is meaningful to improve utilization efficiency (NUE) under low nitrogen (LN) levels while maintaining crop yield. OsCBL1 -knockdown ( OsCBL1- KD) plants exhibited increased nitrogen accumulation and NUE in the field of low N level. Results OsCBL1 -knockdown ( OsCBL1- KD) in rice increased the expression of a nitrate transporter gene OsNRT2.2 . In addition, the expression of OsNRT2.2 , was suppressed by OsCCA1, a negative regulator, which could directly bind to the MYB-binding elements (EE) in the region of OsNRT2.2 promoter. The OsCCA1 expression was found to be down-regulated in OsCBL1- KD plants. At the low Nitrogen (N) level field, the OsCBL1-KD plants exhibited a substantial accumulation of content and higher NUE, and their actual biomass remained approximately as the same as that of the wild type. Conclusion These results indicated that down-regulation of OsCBL1 expression could upregulate the expression of OsNRT2.2 by suppressing the expression of OsCCA1 and then increasing the NUE of OsCBL1-KD plants under low nitrogen availability.

A new method for the synthesis of heterocyclic systems containing tetrazole and tetrahydroisoquinoline is developed via the performance of one-pot Ugi-azide and Heck cyclization reactions. The integration of the multicomponent and post-condensation reactions in one-pot maximizes the pot-, atom-, and step-economy (PASE).

This work focuses on the hot deformation behavior and constitutive models of Ti6Al4V alloy manufactured by directed energy deposition laser (DEDL). The hot compression tests of DEDL Ti6Al4V alloy at deformation temperature of 700–950 °C and strain rate range of 0.001–1 s−1 were carried out. Three phenomenological models including modified Johnson–Cook model, modified Fields–Backofen model, and strain-compensated Arrhenius model were introduced to predict the flow stresses during uniaxial compression. The predictability of the three models is evaluated according to correlation coefficient, average absolute relative error, and average root mean square error. Traditional linear regression method (TLRM) and nonlinear regression analysis (NRA) were used to solve the constants of modified Johnson–Cook model and strain-compensated Arrhenius model, NRA was used to solve the constants of modified Fields–Backofen model. Compared with the TLRM, the NRA improves the accuracy of modified Johnson-Cook model, while has limited effect on that of strain-compensated Arrhenius model. The accuracy of modified Fields–Backofen model and strain-compensated Arrhenius model is higher than that of modified Johnson–Cook model.

Nitrate can directly activate phosphate (Pi) starvation signaling, ultimately promoting plant growth by enhancing phosphorus absorption and utilization and optimizing the balance of nitrogen and phosphorus nutrients. However, the complex mechanisms by which plants integrate complex nutrient signals from nitrogen to phosphorus are not well understood. This study highlights the importance of Calcineurin B-like protein-1 (OsCBL1), a calcium sensor, in coordinating nitrogen and phosphorus signaling in rice. Knockdown of OsCBL1 in rice reduced the expression of genes involved in nitrate-induced Pi starvation responses. In high nitrate conditions, OsCBL1 -KD plants displayed diminished biomass gain, unlike the wild-type rice, which thrived under elevated phosphate levels. In OsCBL1 -KD plants, OsSPX4, a key repressor in nitrogen and phosphorus signaling, remains undegraded in the presence of nitrate due to the significantly reduced expression of OsNRT1.1B . Moreover, the OsCBL1 knockdown hampers the movement of the nitrogen-related transcription factor, OsNLP4, from the cytoplasm to the nucleus when nitrate is present. This impedes the expression of OsNRT1.1B , as OsNLP4 can directly bind to the promoter of OsNRT1.1B nitrate responsive cis-element (NRE) and activate its expression. In summary, these findings suggest that OsCBL1 plays a pivotal role in regulating OsNRT1.1B expression by managing the transport of OsNLP4 between cytoplasm and nucleus in response to nitrate availability. This regulation subsequently influences the phosphate response triggered by nitrate and optimizes the coordinated utilization of nitrogen and phosphorus.

Sprite halos are transient luminous phenomena in the lower ionosphere triggered by tropospheric lightning. The effect of removed charge distributions on sprite halos has not been sufficiently discussed. A three-dimensional (3D) quasi-electrostatic (QES) field model was developed in this paper, including the ionospheric nonlinear effect and optical emissions. Simulation results show that, for a total charge of 150 C removed within 1 ms with different spatial distributions, higher altitudes of charge removal lead to stronger electric fields and increase sprite halos’ emission intensities. The non-axisymmetric horizontal distribution of charge affects mesospheric electric fields, and the corresponding scales and intensities of emissions vary with observation orientations. Considering the tilted dipole charge structure due to wind shear, the generated electric field and the corresponding position of sprite halos shift accordingly with the tropospheric removed charge, providing an explanation for the horizontal displacement between sprite halos and the parent lightning.