Hardening mechanism and thermal-solid coupling model of laminar plasma surface hardening of 65 Mn steel

In the present work,the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel.The mechanical and wear behaviors of the laminar plasma surface hardened 65 Mn steel were analyzed.The martensite transition transformation of the temperature of the laminar plasma-hardened 65 ferrite Mn steel was determined by a thermal-solid coupling model.Based on the orthogonal experimental results,the optimal hardening parameters were confirmed.The scanning velocity,quenching distance and arc current are 130 mm/min,50 mm and 120 A,respectively.The pearlites and ferrites are transformed into martensites in the hardened zone,while the ratio of martensite in the heataffected zone decreases with the increase in the hardening depth.Compared to the untreated 65Mn steel,the average hardness increases from 220 HV_(0.2)to 920 HV_(0.2)in the hardened zone and the corresponding absorbed power increases from 118.7 J to 175.5 J.At the same time,the average coefficient of friction(COF)decreases from 0.763 to 0.546,and the wear rate decreases from 5.39×10^(-6)mm^(3)/(N·m)to 2.95×10^(-6)mm^(3)/(N·m),indicating that the wear resistance of 65Mn steel could be significantly improved by using laminar surface hardening.With the same hardening parameters,the depth and width of the hardened zone predicted by the thermal-solid coupling model are 1.85 mm and 11.20 mm,respectively,which are in accordance with the experimental results;depth is 1.83 mm and width is 11.15 mm.In addition,the predicted hardness distributions of the simulation model are in accordance with the experimental results.These results indicate that the simulation model could effectively predict the microstructure characteristics of 65 Mn steel.

One-pot Synthesis of MoO_(3)/PI Composite with Enhanced Photocatalytic Performance for Oxidative Coupling of Amines to Imines

Organic-inorganic MoO_(3)/PI(MoPI)composites were prepared using a simple one-pot thermal copolymerization method.The resulting composites exhibited enhanced photocatalytic activity for the selective oxidation of benzylamine to N-benzylidene benzylamine(N-BDBA)in ambient air under simulated solar light irradiation compared to pristine MoO_(3) or polyimide(PI).In particular,the MoPI composite with a 0.3:1 molar ratio of Mo to melamine,referred to as MoPI-0.3,demonstrated the best performance in the photo-oxidation of benzylamine,achieving a benzylamine conversion of 95%with a N-BDBA selectivity exceeding 99%after 3 h irradiation.The enhanced photocatalytic activity of the MoPI-0.3 catalyst was attributed to the formation of a direct Z-scheme heterojunction between MoO_(3) and PI,facilitating more efficient separation of the photoinduced electrons and holes.Additionally,the MoPI-0.3 composite maintained considerably high activity over four consecutive cycles,highlighting its good stability and recyclability.Furthermore,the MoPI-0.3 composite could photo-oxidize benzylamine derivatives and heterocyclic amines to their corresponding imines,demonstrating the universal applicability of this composite catalyst.

Cu Stress-Induced Transcriptome Alterations in Sorghum and Expression Analysis of the Transcription Factor-Encoding Gene SbWRKY24

Sorghum is not only an important bio-energy crop but also a vital raw material for brewing.Exogenous copper affects the growth and metabolism of crops in specific ways.This study identified 8475 differentially expressed genes(DEGs)by high-throughput transcriptome sequencing in the sorghum cultivar‘Jinnuoliang 2’after 24 h of treatment with 10 mM CuSO4.Using GO analysis,476 genes were functionally annotated,which were mainly related to catabolism and biosynthetic processes.Additionally,90 pathways were annotated by employing the KEGG analysis.Among them,glutathione metabolism and peroxisome were induced,while photosynthesis,photosynthesis-antenna protein,and carbon sequestration of photosynthetic organisms were inhibited.Of the DEGs,399 were identified to encode transcription factors belonging to 49 families.This study also identified a WRKY transcription factor-encoding gene SbWRKY24 from the transcriptome data.For studying its function,the relative expression levels of SbWRKY24 in roots and leaves post-treatment with different growth hormones and exposure to a variety of abiotic stresses were detected by RT-qPCR.SbWRKY24 showed treatment-and tis-sue-specific expression patterns,indicating its unique role in stress tolerance.This study lays a theoretical basis for the functional exploration of SbWRKY24,elucidating the mechanism of copper resistance,and elaborating on the stress responses in sorghum.It also guides the exploration of the molecular mechanism of copper ions inducing intracellular signal transduction pathways.

Internal electric field modulation by copper vacancy concentration of cuprous sulfide nanosheets for enhanced selective CO_(2) photoreduction

Although the internal electric field(IEF)of photocatalysts is acknowledged as a potent driving force for photocharge separation,modulating the IEF intensity to achieve enhanced photocatalytic performances remains a challenge.Herein,cuprous sulfide nanosheets with different Cu vacancy concentration were employed to study IEF modulation and corresponding direct charge transfer.Among the samples,Cu_(1.8)S nanosheets possessed intensified IEF intensity compared with those of Cu_(2)S and Cu_(1.95)S nanosheets,suggesting that an enhanced IEF intensity could be achieved by introducing more Cu vacancies.This intensified IEF of Cu_(1.8)S nanosheets induced numerous photogenerated electrons to migrate to its surface,and the dissociative electrons were then captured by Cu vacancies,resulting in efficient charge separation spatially.In addition,the Cu vacancies on Cu_(1.8)S nanosheets accumulated electrons as active sites to lower the energy barrier of rate-determining step of CO_(2)photoreduction,leading to the selective conversion of CO_(2)to CO.Herein,the manipulation of IEF intensity through Cu vacancy concentration regulation of cuprous sulfide photocatalysts for efficient charge separation has been discussed,providing a scientific strategy to rationally improve photocata lytic performances for solar energy conversion.

A Metal-free Polyimide Photocatalyst for the Oxidation of Amines to Imines

Polyimide(PI) is an organic polymer material with good stability and diverse sources that has attracted widespread attention in the field of photocatalysis. In this study, a series of PI photocatalysts were synthesized by a thermal polymerization approach using pyromellitic dianhydride(PMDA) and various diamine monomers(melamine(MA), 4,4′-oxydianiline, and melem) as the precursors as well as different heating rates. The effects of the diamine precursor and heating rate on the structure, composition, morphology, and optical properties of the as-prepared PI materials were systematically investigated by various characterization techniques. The selective photo-oxidation of benzylamine was used as a model reaction to evaluate the photocatalytic activities of the resulting PI samples for the oxidation of amines to imines. The results revealed that the PI sample prepared using MA and PMDA as the precursors and a heating rate of 7 ℃/min(MA-PI-7) exhibited the best catalytic performance, with 98% benzylamine conversion and 98% selectivity for N-benzylidene benzylamine after 4 h of irradiation. Several benzylamine derivatives and heterocyclic amines also underwent the photo-oxidation reaction over the MA-PI-7 catalyst to afford the corresponding imines with good activity. In addition, MA-PI-7 exhibited good stability over four successive photocatalytic cycles.

Path Analysis of Rural Social Work Intervention in Precision Poverty Alleviation in Sichuan Province

The targeted poverty alleviation policy isone of the important methods to solve the problemof poverty in China. After the implementation of thetargeted poverty alleviation policy in China, someresults have shown positive. However, due to theshortage of resources and talents for poverty alleviation,there are still some shortcomings in the targeted povertyalleviation work. In the process of targeted povertyalleviation, if we can promote social work to participatein targeted poverty alleviation and use a wider rangeof social forces to provide more professional andtargeted assistance work for the poor, we will achievethe final sprint for the success of targeted povertyalleviation in China and a well-off society. Based onthe actual situation of China’s current targeted povertyalleviation work, this article takes the relationship andcontent of rural social work in Sichuan Province aspart of the targeted poverty alleviation as well as thedifficulties it faces. The analysis focuses on the pathof rural social work in Sichuan Province to targetedpoverty alleviation and aims to provide more referencesuggestions for targeted poverty alleviation in China.

Strengths,Weaknesses,Opportunities,and Threats Analysis and Countermeasures on the Cultivation of Preschool Teachers in Sichuan Province

Training of preschool teachers in Sichuan Province brings advantages in increasing government support for the preschool education industry.The society attaches an important role to the preschool education industry as well as the rapid development of preschool education in Sichuan Province.However,problem exists in large flows of preschool teachers and imbalanced gender ratios.By viewing from the new situation,the comprehensive liberalization of the second-child policy and the development of educational informatization as well as the implementation of the one belt and one road strategy have created great opportunities in training of preschool teachers.At the same time,the increase in external impact of high-quality graduates in the east also poses a great threat to the development of preschool teachers in Sichuan Province.Through the strategic combination of strengths,weaknesses,opportunities,and threats analysis,the paper explores effective countermeasure ways to improve the quality of training of the preschool teachers in Sichuan Province and the construction of an excellent team of preschool teachers in Sichuan Province.

BSTFNet:An Encrypted Malicious Traffic Classification Method Integrating Global Semantic and Spatiotemporal Features

While encryption technology safeguards the security of network communications,malicious traffic also uses encryption protocols to obscure its malicious behavior.To address the issues of traditional machine learning methods relying on expert experience and the insufficient representation capabilities of existing deep learning methods for encrypted malicious traffic,we propose an encrypted malicious traffic classification method that integrates global semantic features with local spatiotemporal features,called BERT-based Spatio-Temporal Features Network(BSTFNet).At the packet-level granularity,the model captures the global semantic features of packets through the attention mechanism of the Bidirectional Encoder Representations from Transformers(BERT)model.At the byte-level granularity,we initially employ the Bidirectional Gated Recurrent Unit(BiGRU)model to extract temporal features from bytes,followed by the utilization of the Text Convolutional Neural Network(TextCNN)model with multi-sized convolution kernels to extract local multi-receptive field spatial features.The fusion of features from both granularities serves as the ultimate multidimensional representation of malicious traffic.Our approach achieves accuracy and F1-score of 99.39%and 99.40%,respectively,on the publicly available USTC-TFC2016 dataset,and effectively reduces sample confusion within the Neris and Virut categories.The experimental results demonstrate that our method has outstanding representation and classification capabilities for encrypted malicious traffic.

Study on concentration distribution and detonation characteristics for non-axisymmetric fuel dispersal

The study of non-axisymmetric fuel dispersal and detonation can provide reference for the prevention of industrial cloud explosion accidents and the design of fuel air explosive(FAE).The concentration and detonation fields of 85 kg cylindrical and fan-shaped fuel are investigated by experiments and numerical simulations.A dynamic model of the whole process for fuel dispersal and detonation is built.The concentration distribution of fuel is used as the initial condition to calculate the detonation stage,thus solving the initial value problem of detonation field.The phase and component changes of fuel cloud at different locations are compared.The fuel cloud is divided into directions of 0°,90°,135°and 180°.The results show that the maximum cloud radius is 20.94 m in 135°and the minimum is 12.04 m in 0°.The diameter of the detonation fireball is 53.6 m,and the peak temperature is 3455 K.The highest peak overpressure is 3.44 MPa in 0°and the lowest is 2.97 MPa in 135°.The proportion of liquid phase in 0°is22.90%,and the fuel loss is 11.8% and 9% higher than that in 135°and cylindrical charge,respectively.The stable propagation distance of blast wave in 135°is 42.50% longer than 0°and 28.37% longer than cylindrical charge.

A Gaussian Noise-Based Algorithm for Enhancing Backdoor Attacks

Deep Neural Networks(DNNs)are integral to various aspects of modern life,enhancing work efficiency.Nonethe-less,their susceptibility to diverse attack methods,including backdoor attacks,raises security concerns.We aim to investigate backdoor attack methods for image categorization tasks,to promote the development of DNN towards higher security.Research on backdoor attacks currently faces significant challenges due to the distinct and abnormal data patterns of malicious samples,and the meticulous data screening by developers,hindering practical attack implementation.To overcome these challenges,this study proposes a Gaussian Noise-Targeted Universal Adversarial Perturbation(GN-TUAP)algorithm.This approach restricts the direction of perturbations and normalizes abnormal pixel values,ensuring that perturbations progress as much as possible in a direction perpendicular to the decision hyperplane in linear problems.This limits anomalies within the perturbations improves their visual stealthiness,and makes them more challenging for defense methods to detect.To verify the effectiveness,stealthiness,and robustness of GN-TUAP,we proposed a comprehensive threat model.Based on this model,extensive experiments were conducted using the CIFAR-10,CIFAR-100,GTSRB,and MNIST datasets,comparing our method with existing state-of-the-art attack methods.We also tested our perturbation triggers using various defense methods and further experimented on the robustness of the triggers against noise filtering techniques.The experimental outcomes demonstrate that backdoor attacks leveraging perturbations generated via our algorithm exhibit cross-model attack effectiveness and superior stealthiness.Furthermore,they possess robust anti-detection capabilities and maintain commendable performance when subjected to noise-filtering methods.

Structure transformation induced bi-component Co–Mo/A-Co(OH)_(2)as highly efficient hydrogen evolution catalyst in alkaline media

Elucidating the inherent origins of the sluggish hydrogen evolution reaction(HER)kinetics in alkaline media and developing high-performance electrocatalysts are fundamental for the advances of conventional alkaline water electrolyzers and emerging anion exchange membrane(AEM)electrolyzers.Here we present a facile electrochemical modification strategy for the synthesis of bi-component Co–Mo_((18%))/A-Co(OH)_(2)catalyst toward efficient HER catalysis in alkaline media.Porous Co–Mo alloys with adjustable Mo/Co atomic ratio are first prepared by H2-assisted cathodic electrodeposition.By virtue of the appropriate electronic structure and hydrogen binding energy,Co–Mo_((18%))is the most HER active among the alloys and is further activated by a constant-current electrochemical modification process.Physical characterizations reveal the formation of amorphous Co(OH)_(2)nanoparticles on the surface.Electrokinetic analysis combined with theoretical calculations reveal that the in-situ formed Co(OH)_(2)can efficiently promote the water dissociation,resulting in accelerated Volmer-step kinetics.As a result,the Co–Mo_((18%))/A-Co(OH)_(2)simultaneously achieves the optimization of the two factors dominating alkaline HER activity,i.e.,water dissociation and hydrogen adsorption/desorption via the bifunctional synergy of the bi-components.The high HER activity(η10 of 47 mV at 10 mA cm^(-2))of Co–Mo_((18%))/A-Co(OH)_(2)is close to benchmark Pt/C catalyst and comparable or superior to the most active non-noble metal catalysts.

A Search for Radio Pulsars in Supernova Remnants Using FAST with One Pulsar Discovered

We report the results of a search for radio pulsars in five supernova remnants(SNRs)with the FAST telescope.The observations were made using the 19-beam receiver in“snapshot”mode.The integration time for each pointing was 10 min.We discovered a new pulsar,PSR J1845–0306,which has a spin period of 983.6 ms and a dispersion measure of 444.6±2.0 cm^(−3)·pc,in observations of SNR G29.6+0.1.To judge the association between the pulsar and the SNR,further verification is needed.We also re-detected some known pulsars in the data from SNRs G29.6+0.1 and G29.7–0.3.No pulsars were detected in the observations of the other three SNRs.

Simulation of an imaging system for internal contamination of lungs using MPA-MURA coded-aperture collimator

The nuclides inhaled during nuclear accidents usually cause internal contamination of the lungs with low activity.Although a parallel-hole imaging system,which is widely used in medical gamma cameras,has a high resolution and good image quality,owing to its extremely low detection efficiency,it remains difficult to obtain images of inhaled lung contamination.In this study,the Monte Carlo method was used to study the internal lung contamination imaging using the MPA-MURA coded-aperture collimator.The imaging system consisted of an adult male lung model,with a mosaicked,pattern-centered,and anti-symmetric MURA coded-aperture collimator model and a CsI(Tl)detector model.The MLEM decoding algorithm was used to reconstruct the internal contamination image,and the complementary imaging method was used to reduce the number of artifacts.The full width at half maximum of the I-131 point source image reconstructed by the MPAMURA coded-aperture imaging reached 2.51 mm,and the signal-to-noise ratio of the simplified respiratory tract source(I-131)image reconstructed through MPA-MURA coded-aperture imaging was 3.98 dB.Although the spatial resolution of MPA-MURA coded-aperture imaging is not as good as that of parallel-hole imaging,the detection efficiency of PMA-MURA coded-aperture imaging is two orders of magnitude higher than that of parallel-hole collimator imaging.Considering the low activity level of internal lung contamination caused by nuclear accidents,PMA-MURA coded-aperture imaging has significant potential for the development of lung contamination imaging.

On the improved tensile strength and ductility of Mg-Sn-Zn-Mn alloy processed by aging prior to extrusion

This study investigated the influence of aging prior to extrusion(APE)on the tensile strength and ductility of as-extruded Mg-8.32Sn-1.85Zn-0.17Mn alloy.Results demonstrated that APE treatment dramatically increased the volume fraction of recrystallized grains,thereby decreasing the grain size of the as-extruded alloy.This phenomenon was primarily attributed to the particle-stimulated nucleation and pinning effect induced by large amounts of small Mg 2 Sn precipitates produced by the APE treatment and dynamic precipitation.The tensile yield strength increased from 242.4 MPa to 256.5 MPa after APE treatment.The improved tensile strength can be attributed to the enhanced grain boundary strengthening and precipitation strengthening.The ductility of the as-extruded alloy also markedly increased from 7.1%to 13.5%after the APE treatment.The improved ductility of APE alloy was attributed to the texture randomization,the activity of pyramidal<c+a>slip and the suppressed formation of{10-11}contraction twins and coarse Mg 2 Sn phases.

Theoretical Study on the Mechanism of VO_2^+ + H_2 Reaction in the Gas Phase

The mechanism of VO2＋ ＋ H2 reaction in the gas phase was investigated by using density functional theory （DFT） at the CCSD//B3LYP/6-311G（2d, p） level. According to our calculation results, the different reaction mechanisms were found for the singlet and triplet potential energy surfaces （PESs）. Especially, the crossing points （CPs） among different PESs were located by means of the intrinsic reaction coordinate （IRC） approach presented by Yoshizawa et al., and the structures and energies of the corresponding minimum energy crossing points （MECPs） were obtained by the mathematical algorithm proposed by Harvey et al. Finally, the frontier molecular orbital （FMO） interaction analyses about MECP1 and MECP2 were used to prove our calculation results.

Carboniferous ridge subduction in the Xingmeng Orogenic Belt:Constraints from geochronological,geochemical,and Sr-Nd-Hf isotopic analysis of strongly peraluminous granites and gabbro-diorites in the Xilinhot micro-continent

The Xingmeng Orogenic Belt evolved through a long-lived orogeny involving multiple episodes of subduction and accretion.However,there is a debate on its tectonic evolution during the Late Paleozoic.Here,we report geochemical,geochronological,and isotopic data from strongly peraluminous granites and gabbro-diorites from the Sunidzuoqi-Xilinhot region.Zircon U-Pb ages suggest that the intrusive rocks were emplaced during the Early Carboniferous(333-322 Ma).The granites exhibit geochemical characteristics similar to S-type granites,with high SiO_(2)(72.34-76.53 wt.%),Al_(2)O_(3)(12.45-14.65 wt.%),and A/CNK(1.07-1.16),but depleted Sr,Nb,and Ta contents.They exhibit positiveε_(Nd)(t)andε_(Hf)(t)values(-0.3 to 2.8 and 2.7-5.7,respectively)and young Nd and Hf model ages(T_(DM2)(Nd)=853-1110 Ma and T_(DM2)(Hf)=975-1184 Ma),suggesting that they may be the partial melting products of heterogeneous sources with variable proportions of pelite,psammite,and metabasaltic rocks.The meta-gabbro-diorites from the Maihantaolegai pluton have low SiO_(2)(47.06-53.49 wt.%)and K_2O(0.04-0.99 wt.%)contents,and demonstrate slight light rare earth element(REE)depletion in the chondritenormalized REE diagrams.They have high zirconε_(Hf)(t)values(14.41-17.34)and young Hf model ages(T_(DM2)(Hf)=230-418 Ma),indicating a more depleted mantle source.The variations of the Sm/Yb and La/Sm ratios can thus be used to assess the melting degree of the mantle source from 5%to 20%,suggesting a quite shallow mantle melting zone.We propose that the petrogenesis and distribution of the strongly peraluminous granites and gabbro-diorites,as well as the tectonic architecture of the region,can be explained by a ridge subduction model.Based on these results,and previous studies,we suggest a southward ridge subduction model for the Sunidzuoqi-Xilinhot region.

Computational Analysis of Artimisinin Derivatives on the Antitumor Activities

The study on antitumor activities of artemisinin and its derivatives has been closely focused on in recent years.Herein,2D and 3D QSAR analysis was performed on the basis of a series of artemisinin derivatives with known bioactivities against the non-small-cell lung adenocarcinoma A549 cells.Four QSAR models were successfully established by CoMSIA,CoMFA,topomer CoMFA and HQSAR approaches with respective characteristic values q^(2)=0.567,R2=0.968,ONC=5;q^(2)=0.547,R2=0.980,ONC=7;q^(2)=0.559,R^(2)=0.921,ONC=7 and q^(2)=0.527,R^(2)=0.921,ONC=6.The predictive ability of CoMSIA with r^(2)=0.991 is the best one compared with the other three approaches,such as CoMFA(r^(2)=0.787),topomer CoMFA(r^(2)=0.819)and HQSAR(r^(2)=0.743).The final QSAR models can provide guidance in structural modification of artemisinin derivatives to improve their anticancer activities.

Telmisartan Attenuates the Growth of Epithelium-like Cells and Glomerular Injury in Spontaneously Hypertensive Rats

The abnormal growth of epithelium-like cells has been noticed in spontaneously hypertensive rats(SHRs)with hypertensive nephropathy.However,the characteristics of abnormal epithelium-like cells and their pathogenesis in hypertensive nephropathy are not fully understood.In the present study,we investigated the correlation of epithelium-like cells with glomerular injury,and the effects of early drug intervention with telmisartan,an anti-hypertensive drug,on the growth of epithelium-like cells.The results showed that the epithelium-like cells were obviously observed lining along the luminal surface of Bowman’s capsule in glomeruli,significantly resulting in the atrophy of the glomerular tuft.Some of the epithelium-like cells strongly expressed proliferating cell nuclear antigen(PCNA)and vimentin,indicating active cellular proliferation.The incidence of epithelium-like cells varied from 13.6%to 54.4%of glomeruli in 48-week-old SHRs,and from 5.1%to 18.0%of glomeruli in age-matched Wistar-Kyoto(WKY)rats(P<0.01).The linear regression analysis further confirmed an obvious correlation between the incidence of epithelium-like cells and the glomerular injury.Moreover,early intervention with telmisartan could dramatically attenuate the progression of epithelium-like cells growth.However,no significant effect of telmisartan on the established epithelium-like cells was observed.Taken together,we demonstrated the involvement of abnormal epithelium-like cells growth in glomerular injury during hypertensive nephropathy in SHRs,and firstly showed the positive effects of the anti-hypertensive drug on the progression of epithelium-like cells growth.

Synergistic regulation of current-carrying wear performance of resin matrix carbon brush composites with tungsten copper composite powder

Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.

Probing structural and electronic properties of divalent metal Mg_(n+1) and SrMgn (n=2–12) clusters and their anions

Divalent metal clusters have received great attention due to the interesting size-induced nonmetal-to-metal transition and fascinating properties dependent on cluster size,shape,and doping.In this work,the combination of the CALYPSO code and density functional theory(DFT)optimization is employed to explore the structural properties of neutral and anionic Mg_(n+1) and SrMgn(n=2-12)clusters.The results exhibit that as the atomic number of Mg increases,Sr atoms are more likely to replace Mg atoms located in the skeleton convex cap.By analyzing the binding energy,second-order energy difference and the charge transfer,it can be found the SrMg9 cluster with tower framework presents outstanding stability in a studied size range.Further,bonding characteristic analysis reveals that the stability of SrMg9 can be improved due to the strong s-p interaction among the atomic orbitals of Sr and Mg atoms.