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Biochar can effectively reduce the phytoavailability of mercury (Hg) in soil, but the mechanisms are not fully understood. In this study, the dynamic changes in Hg content adsorbed by the biochar (BC-Hg), Hg phytoavailability in the soil (P-Hg), and soil dissolved organic matter (DOM) characteristics were determined over a 60-day treatment period. Biochar obtained at 300 °C, 500 °C and 700 °C reduced the P-Hg concentration assessed by MgCl2 extraction by 9.4%, 23.5% and 32.7%, respectively. However, biochar showed a very limited adsorption on Hg, with the maximum BC-Hg content only accounting for 1.1% of the total amount. High-resolution scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) results showed that the proportion of Hg atoms in biochar after 60 d was barely detectable. Biochar treatment can shift soil DOM toward higher aromatic content and molecular weight. Additionally, the addition of high-temperature biochar increased more humus-like components, but low-temperature biochar increased more protein-like components. Correlation analysis and partial least squares path modeling (PLS-PM) showed that biochar promoted humus-like fractions formation to reduce the Hg phytoavailability. This research has deepened the understanding of the mechanisms by which biochar stabilizes Hg in agricultural soils.

This paper is focused on the following Schrödinger–Poisson system − Δ u + V ( x ) u + ϕ u = f ( u ) , x ∈ R 3 , − Δ ϕ = u 2 , x ∈ R 3 , where V ( x ) is weakly differentiable and tends asymptotically to a constant and f ∈ C ( R , R ). By introducing some new tricks, we prove that the above system admits a ground state solution under some mild assumptions on V and f. Our results generalize and improve the existing ones in the literature.

Comprehensive optimization design of serpentine nozzle with trapezoidal outlet was studied to improve its aerodynamic and electromagnetic scattering performance. Serpentine nozzles with different center offsets and different ratios of the bases of the trapezoidal outlet were generated based on curvature control regulation. Computational Fluid Dynamics (CFD) simulations have been conducted to obtain the flow field in the nozzle, and Forward-Backward Iterative Physical Optics (FBIPO) method was applied to study the electromagnetic scattering characteristics of the nozzle. Guarantee Convergence Particle Swarm Optimization (GCPSO) algorithm based on Radial Basis Function (RBF) neural network was used to optimize the geometry of the nozzle in consideration of its aerodynamic and electromagnetic scattering characteristics. The results show that the GCPSO method based on RBF can be used to optimize the aerodynamic characteristics of the internal flow and the scattering characteristics of the cavity of the serpentine nozzle with irregular outlet. The optimized model has a higher center offset and a lower ratio of the bases of the trapezoidal outlet after optimization compared to the original model. The optimized model leads to a slight change in aerodynamic performance, with a total pressure recovery coefficient increase of 0.31% and a discharge coefficient increase of 0.41%. In addition, the Radar Cross Section (RCS) decreases also by around 83.33% and the overall performance is significantly improved, with a decrease of the optimized objective function by around 38.74%.

Inhibitory leukocyte immunoglobulin-like receptors (LILRBs 1–5) transduce signals via intracellular immunoreceptor tyrosine-based inhibitory motifs that recruit phosphatases to negatively regulate immune activation. The activation of LILRB signaling in immune cells may contribute to immune evasion. In addition, the expression and signaling of LILRBs in cancer cells especially in certain hematologic malignant cells directly support cancer development. Certain LILRBs thus have dual roles in cancer biology—as immune checkpoint molecules and tumor-supporting factors. Here, we review the expression, ligands, signaling, and functions of LILRBs, as well as therapeutic development targeting them. LILRBs may represent attractive targets for cancer treatment, and antagonizing LILRB signaling may prove to be effective anti-cancer strategies.

Portable document format (PDF) files are increasingly used to launch cyberattacks due to their popularity and increasing number of vulnerabilities. Many solutions have been developed to detect malicious files, but their accuracy decreases rapidly in face of new evasion techniques. We explore how to improve the robustness of classifiers for detecting adversarial attacks in PDF files. Content replacement and the n-gram are implemented to extract robust features using proposed guiding principles. In the two-stage machine learning model, the objects are divided based on their types, and the anomaly detection model is first trained for each type individually. The former detection results are organized into tree-like information structure and treated as inputs to convolutional neural network. Experimental results show that the accuracy of our classifier is nearly 100% and the robustness against evasive samples is excellent. The object features also enable the identification of different vulnerabilities exploited in malicious PDF files.

Transcutaneous electrical acupoint stimulation (TEAS) is a noninvasive and therapeutic technique that stimulated the acupoint by delivering electricity. Whether TEAS could relieve cancer-related fatigue (CRF), anxiety, and depression and improve the quality of life in cancer patients remains controversial. Thus, we conducted a thorough literature search of electronic Chinese and English databases for randomized controlled trials (RCTs) reporting the effect of CRF, anxiety, depression, and quality of life in cancer patients from inception to July 1st, 2021. The Cochrane Collaboration Risk of Bias criteria were used to assess the risk of bias for each included RCT. Continuous variables were analyzed using standardized mean difference (SMD) and 95% confidence interval (CI). A fixed-effects model was used for the meta-analysis of all outcomes. A total of nine RCTs with 924 cancer patients were included in this analysis, including 460 patients in the interventional group and 464 patients in the control group. We found that TEAS could significantly reduce CRF, depression, and anxiety (SWD = −0.83, 95% CI: −0.99 to −0.66, P < 0.05 ) and improve the quality of life (SWD = −1.37, 95% CI: −2.34 to −0.40, P < 0.05 ). The funnel plot analysis revealed no significant publication bias. We conclude that TEAS is beneficial for reducing CRF, depression, and anxiety and improving the quality of life of cancer patients, but additional high-quality evidence in the future is entailed to support this.

As the last part of the convergent divergent nozzle, the divergent section is exposed to high temperature and high-speed airflow and thus, it is more easily to be detected by the infrared detector. It is one of the main sources of the infrared radiation in the exhaust system. Film cooling is applied to protect the wall from hot flow and reduce the infrared radiation. In this paper, the study is conducted on a nozzle with spherical convergence flap in a turbofan engine exhaust system. The effect of film cooling on the internal flow and infrared radiation characteristics of the exhaust system in the divergent section was studied by numerical simulations. The k-ω SST turbulence model was used to simulate the flow field, and the Reverse Monte Carlo Method was employed to calculate the infrared radiation characteristics of the nozzle. Four different kinds of film hole arrangements are involved, they are cylindrical film holes in an in-line pattern, cylindrical film holes in a staggered pattern, converging-expanding film holes in an in-line pattern and converging-expanding film holes in a staggered pattern. The cylindrical film hole and the converging-expanding film hole have a round shape inlet, with an equivalent diameter of d = 5mm on the projection surface perpendicular to the axial direction. Angles between each film hole and the wall surface are 35°. The impact of the heat conduction on the wall was taken into account. The results show that with the given mass flow rate of the coolant, the lengths of the high temperature core zone of the four models with different film cooling structures are slightly shorter than the core zone of the model without cooling structures. However, no significant difference can be found for the length of the core zone of the four models. The average temperature of the wall in the divergent section decreases significantly by using film cooling. No significant difference can be found in the wall temperature distribution for the four models. In the 3∼5μm and 8∼14μm bands, the cooling technique barely affects the infrared radiation of the main exhaust jet flow, while it significantly reduces the infrared radiation of the solid wall in the divergent section, and the decreasing amplitude is from 45% to 51%. Different film hole arrangements result in similar effects on the infrared radiation of the nozzle. Overall, the usage of film cooling in the divergent section of the nozzle effectively reduces the averaged wall temperature and substantially suppresses the solid infrared radiation on the wall. However, the shape and arrangement of the film holes have no significant influence on the infrared radiation intensity and temperature of the wall in the divergent section.

Searching for the optimal solution of the comprehensive performance of the aerodynamic and stealth characteristics of the aircraft inlet has become the trend of the development of the aircraft inlet due to the rapid development of radar detection technology. The aircraft inlet is a vital source of scattering due to its own cavity structure characteristic. Accordingly, reducing the electromagnetic stealth characteristic value of the stealth aircraft inlet can be served as the main way to reduce the RCS value of the whole airplane. Accordingly, a new type of stealth aircraft inlet that incorporates the design of the inner bulge is designed in this paper, which significantly reduces the value of radar-cross section (RCS) of the inlet by transforming the three-dimensional shape of the inlet. The design of this kind of inlet is based on the parametric rapid reconstruction geometry method that produces a geometry profile of the inlet through controlling a limited number of characteristic parameters. At the same time, the profile coordinates of the inner bulge is decided by means of three parameters, including the area of inner bulge, the circumferential distance and the radial offset. This paper calculates the aerodynamic characteristics of the seven S-shaped inlets, including six S-shaped inlets incorporated the inner bulges with different parameters, and an ordinary S-shaped inlet without the inner bulge as a control model. Total pressure recovery and distortion index are used as the indicators for judging the flow characteristics of these inlets to evaluate the effects on the aerodynamic characteristics of the stealth inlet after incorporating the inner bulge, which plays an important role in further evaluating the influence of the working environment of the compressor after the inlet. These S-shaped inlets with inner bulges on them resulting a decrease on total pressure recovery by 0.69% to 1.14%, at the same time, the total pressure distortion index at the exit of inlet is increased by 14.77% to 26.85%. Overall, the aerodynamic performance of the inlet with the design of the inner bulge can’t be seen a large decline. What’s more, this paper also compares the electromagnetic properties of the S-shaped inlet models with the inner bulge with the inlet without the inner bulge, using the algorithm of iterative physical optics (IPO) to evaluate the stealth characteristics of the models. This method is a kind of high-frequency approximation method for analyzing the scattering characteristics of the cavity scattering, with the high calculation accuracy as well as the high calculation efficiency. At the same time, the calculation takes up less memory, this is simply because that the mesh is coarser in calculation when using the IPO algorithm. The resulting inlet design achieving a dramatic improvement in stealth performance that the value of RCS is reduced by up to 97% after incorporating the design of inner bulge. In general, the stealth characteristics of optimized stealth aircraft inlet has greatly improved.

We consider the following semilinear Schrodinger equation with inverse square potential \begin{document}$\begin{array}{l}\left\{ \begin{align} & -\vartriangle u+(V(x)-\frac{\mu }{|x{{|}^{2}}}u=f(x,u),\ \ \ \ \ x\in {{\mathbb{R}}^{N}}, \\ & u\in {{H}^{1}}({{\mathbb{R}}^{N}}), \\ \end{align} \right.\end{array}$ \end{document} where $N≥ 3$, $f$ is asymptotically linear, $V$ is 1-periodic in each of $x_1, ..., x_N$ and $\sup[σ(-\triangle +V)\cap (-∞, 0)]＜0＜{\rm{inf}}[σ(-\triangle +V)\cap (0, ∞)]$. Under some mild assumptions on $V$ and $f$, we prove the existence and asymptotical behavior of ground state solutions of Nehari-Pankov type to the above problem.

With the outbreak of the COVID-19, most students can only take classes online at home. However, many students cannot consciously control their learning behaviors when they are in class at home, and some negative learning behaviors such as sleeping on the table or wandering have appeared. These negative learning behaviors greatly affect the effectiveness of learning. In order to deal with these problems, a online teaching system based on human action recognition is developed to assist teachers in real-time capturing the class status of classmates and improve the efficiency of home-based online teaching. Here, the system uses the OpenPose human body gesture recognition algorithm to obtain the key points of the student's body in class in front of the camera, and recognizes the student's class behavior through the analysis of the coordinates. The RTMP protocol is used to solve the problem of audio and video transmission during the live broadcast. We have conducted experiments to show the effectiveness of our system for analyzing the status of students and evaluating the online class.

The electromagnetic scattering characteristics of the inlet with grilles are calculated to verify the feasibility to reduce the radar cross section by installation of grilles. The Method of Moment (MOM) is used to calculate the models. According to its complicated structures, the inlet with grilles is simplified and the structured mesh is applied to specify the minor features of a large quantity of grilles to obtain aerodynamic characteristics of these models. The SST k-ω turbulence model based on the RANS method is utilized to simulate the air flow through the inlet. A clear duct with the geometric parameters (180mm 180mm 400mm) as well as the duct with grilles involving different parameters (shapes, thickness) is applied for the numerical simulation at the speed of 0.6 Mach at a certain range of angles of attack. Grilles in different parameters are simulated separately and compared with the clear inlet and the inlet with grilles, to find an approximate but simple method to estimate the aerodynamic influence taken by the different grilles. The results implicate that grille installation in the inlet has a significant positive influence on electromagnetic stealth performance. RCS drops by 4.80dBsm at an angle of attack of 0°. Meanwhile, substantial RCS reduction at range of angle of attack from 0°to 20° is found. Thickness and shape have remarkable influence on aerodynamic performance instead of electromagnetic scattering characteristics (f=1GHz, VV). The couple of grilles and inlet duct shows a little effect on aerodynamic characteristics compared with the single-element grille. It is acceptable to simulate grilles with inlet by numerically calculating the single-element grille.

Using the improved ray tracing method to improve the reverse Monte Carlo (RMC) method, which is used to analyze the infrared radiation (IR) characteristics of the exhaust system, can greatly improve the computational efficiency and accuracy, and the calculation accuracy is improved by more than 8% compared with the RMC using ray tracing algorithm. For a flying wing unmanned aerial vehicle (UAV), the influence of the geometry of the double S-shaped nozzles and the single S-shaped nozzles on the internal flow field were analyzed, then the influence of the internal and external flow on the aerodynamic performance of the S-shaped exhaust system, and the IR characteristics of the aircraft with different inlet and exhaust system in the 3μm-5μm and 8μm-14μm bands were studied. The aerodynamic performance of the S-shaped nozzles are studied by numerical simulations. The IR characteristics of the rear hemisphere on the single S-shaped nozzles and the double S-shaped nozzles were obtained, those nozzles have the similar engine matching performance. The double S-shaped nozzle, resulting in a decrease of the radiation intensity of the nozzle by at least 65%, compared to the single S-shaped nozzle in the 3μm-5μm band. The aerodynamic characteristics of the flying wing UAV with the two S-shaped exhaust systems are also compared, and the changes in lift and resistance are analyzed. The forward IR intensity of the flying wing UAV is significantly lower than that of the backward direction, and the upper direction IR intensity is higher than that of the lateral direction and the downward direction. Compared to the flying wing UAV with the single S-shaped exhaust system, the flying wing of the double S-shaped exhaust system has a lower IR intensity, for the peak intensity of the rear hemisphere in the 3μm-5μm band is reduced at least 80%, the maximum value of the locked distance is reduced to 25% of the UAV using the single S curved exhaust system. The ratio of the amount of aircraft skin radiation to the total radiation increases from 30% in the 3μm-5μm band to more than 70% in the 8μm-14μm band. From the results of spectral analysis of UAV from 13μm-14μm, the spectral radiance of the carbon dioxide absorption and emission band in the detector image is significantly less than that of the UAV with a single S-shaped nozzle.

Serpentine inlet is widely used in military and civil aircraft due to its good stealth performance. However, it generates a high total pressure loss and swirl distortion which significantly affects the performance and the stability of the compressor. In order to improve the quality of the flow field at the aerodynamic interface plane (AIP), a flow control is required inside the serpentine inlet. The objective of this paper was to study the effectiveness of the blowing active flow control on reducing the swirl distortion and on improving the total pressure recovery at the AIP, by reducing the low-momentum flow in the serpentine inlet. The mechanism of the blowing control and the effect of the design parameters (i.e. blowing angle, blowing position and blowing flow rate) on the aerodynamic performance at the AIP were studied. The optimal solution was applied to the full flow path of the serpentine inlet and the fan-stage. The numerical results showed that the quality of the flow field at the AIP were effectively improved by blowing high-energy airflow into the boundary layer of the serpentine inlet. The blowing position had a high influence on the blowing effect, and upper wall blowing scheme obtained greater benefits than lower wall blowing scheme and combination blowing scheme. In addition, the blowing angle should be selected to avoid the high-energy air from pipes mixing with mainstream in the serpentine inlet which will result in an additional total pressure loss. When the ratio of the blowing mass flow rate to the designed mass flow rate of the serpentine inlet was about 1.5%, the swirl distortion on the AIP reached a minimum value, which then did not show a significant difference in performance with blowing ratio increased. When the upper wall blowing scheme was adopted with a blowing angle of 6 degrees and a blowing ratio of 1.5%, the AIP aerodynamic performance achieved the highest improvement, with an increase of the total pressure recovery factor by about 1%, and a decrease of the circumferential total pressure distortion and the swirling distortion by 60% and 61%, respectively. With the optimal control scheme, the area of the low-pressure region near the upper wall was remarkably reduced, and the performance of fan-stage was improved, with an increase of the pressure ratio by about 1.5%, and the efficiency of the single-stage compressor by about 3.1%, respectively.

In this paper, we consider the following critical Kirchhoff type equation:By using variational methods that are constrained to the Nehari manifold, we prove that the above equation has a ground state solution for the case when 3 < q < 5. The relation between the number of maxima of Q and the number of positive solutions for the problem is also investigated.

Employing the minimax method incorporated with invariant sets of descending flow, we prove some results about the existence of sign-changing solutions for a class of Kirchhoff-type equation. In particular, a sequence of high-energy sign-changing solutions is obtained.

Employing some new analytical skills and the non-Nehari manifold method, we prove some results about the existence of ground and bound states of the following non-linear Schrodinger system

This paper is concerned with the following Kirchhoff type equation: { - ( a + b ? ? | ? v | 2 ) Δ v = f ( x , v ) in ? , v = 0 on ? ? . Assuming that the primitive of f is asymptotically 4-linear as | v | ? ∞ , a homeomorphism between the Nehari manifold and a subset of unit sphere is constructed based on some observations and new techniques. Inspired by recent work of Szulkin and Weth (2010), ground state solutions for the equation above are obtained, as well as infinitely many pairs of nontrivial solutions for case f ( x , v ) ?is odd with respect to v .

In Neurospora crassa, the methionine synthase gene met-8 plays a key role in methionine synthesis. In this study, we found that MET-8 protein levels were compromised in several mutants defective in proper heterochromatin formation. Bioinformatics analysis revealed a 50-kb AT-rich region adjacent to the met-8 promoter. ChIP assays confirmed that trimethylated H3K9 was enriched in this region, indicating that heterochromatin may form upstream of met-8. In an H3K9R mutant strain, the output of met-8 was dramatically reduced, similar to what we observed in mutant strains that had defective heterochromatin formation. Furthermore, the production of ectopically expressed met-8 at the his-3 locus in the absence of a normal heterochromatin environment was inefficient, whereas ectopic expression of met-8 downstream of two other heterochromatin domains was efficient. In addition, our data show that the expression of mig-6 was also controlled by an upstream 4.2-kb AT-rich region similar to that of the met-8 gene, and we demonstrate that the AT-rich regions adjacent to met-8 or mig-6 are required for their peak expression. Our study indicates that met-8 and mig-6 may represent a novel type of gene, whose expression relies on the proper formation of a nearby heterochromatin region.

Aiming at reducing the high False Negative rate of the existing Trojan horse detection method based on behavior, this paper utilized the sequence characteristics of tunnel Trojan communication extracted from the transport layer and the bi-directional recurrent neural network in deep learning to build a HTTP tunnel Trojan detection model. The experimental result showed that the deep learning-based detection model reduced the false positive rate of normal network traffic and improved the Trojan detection rate. We also found that the deep learning-based detection model reduced the feature selecting and data cleaning process of generating samples and improved the easy-using of the HTTP tunnel Trojan detection model.

Although the coupling between circadian and cell cycles allows circadian clocks to gate cell division and DNA replication in many organisms, circadian clocks were thought to function independently of cell cycle. Here, we show that DNA replication is required for circadian clock function in Neurospora. Genetic and pharmacological inhibition of DNA replication abolished both overt and molecular rhythmicities by repressing frequency (frq) gene transcription. DNA replication is essential for the rhythmic changes of nucleosome composition at the frq promoter. The FACT complex, known to be involved in histone disassembly/reassembly, is required for clock function and is recruited to the frq promoter in a replication-dependent manner to promote replacement of histone H2A.Z by H2A. Finally, deletion of H2A.Z uncoupled the dependence of the circadian clock on DNA replication. Together, these results establish circadian clock and cell cycle as interdependent coupled oscillators and identify DNA replication as a critical process in the circadian mechanism.