Preheating-assisted solid-state friction stir repair of Al-Mg-Si alloy plate at different rotational speeds

Additive friction stir deposition(AFSD)is a novel structural repair and manufacturing technology has become a research hotspot at home and abroad in the past five years.In this work,the microstructural evolution and mechanical performance of the Al-Mg-Si alloy plate repaired by the preheating-assisted AFSD process were investigated.To evaluate the tool rotation speed and substrate preheating for repair quality,the AFSD technique was used to additively repair 5 mm depth blind holes on 6061 aluminum alloy substrates.The results showed that preheat-assisted AFSD repair significantly improved joint bonding and joint strength compared to the control non-preheat substrate condition.Moreover,increasing rotation speed was also beneficial to improve the metallurgical bonding of the interface and avoid volume defects.Under preheating conditions,the UTS and elongation were positively correlated with rotation speed.Under the process parameters of preheated substrate and tool rotation speed of 1000 r/min,defect-free specimens could be obtained accompanied by tensile fracture occurring in the substrate rather than the repaired zone.The UTS and elongation reached the maximum values of 164.2MPa and 13.4%,which are equivalent to 99.4%and 140%of the heated substrate,respectively.

Centrifuge modeling of unreinforced and multi-row stabilizing piles reinforced landslides subjected to reservoir water level fluctuation

With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been recorded.In recent years,multi-row stabilizing piles(MRSPs)have been used to stabilize massive reservoir landslides in China.In this study,two centrifuge model tests were carried out to study the unreinforced and MRSP-reinforced slopes subjected to reservoir water level(RWL)operation,using the Taping landslide as a prototype.The results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force,eventually strengthening the slope stability.However,a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect,consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation zone.Furthermore,partial deformation and subsequent soil structure damage generate excess pore water pressures,ultimately leading to the overall failure of the reservoir landslide.This study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the MRSPs.Conversely,the MRSPs possess a considerable reinforcement effect on the reservoir landslide,transforming the overall failure into a partial deformation and failure situated above and in front of the MRSPs.The mechanical transfer behavior observed in the MRSPs demonstrates a progressive alteration in relation to RWL fluctuations.As the RWL rises,the mechanical states among MRSPs exhibit a growing imbalance.The shear force transfer factor(i.e.the ratio of shear forces on pile of the n th row to that of the first row)increases significantly with the RWL drawdown.This indicates that the mechanical states among MRSPs tend toward an enhanced equilibrium.The insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of MRSPs in reservoir banks.

Ancient DNA unravels species identification from Laosicheng site,Hunan Province,China,and provides insights into maternal genetic history of East Asian leopards

DEAR EDITOR,The Laosicheng site in Yongshun County,Hunan Province,China,plays an important role in elucidating the animal population composition of the region prior to the middle Qing Dynasty(approximately 300 years ago).This site has yielded a substantial number of animal bones,11960 of which have been identified to the species level,serving as direct evidence of ancient animal populations(Hunan Provincial Institute of Cultural Relics and Archaeology,2018).

Identification of anti-gastric cancer effects and molecular mechanisms of resveratrol: From network pharmacology and bioinformatics to experimental validation

BACKGROUND Gastric cancer(GC)is one of the most aggressive malignancies with limited therapeutic options and a poor prognosis.Resveratrol,a non-flavonoid poly-phenolic compound found in a variety of Chinese medicinal materials,has shown excellent anti-GC effect.However,its exact mechanisms of action in GC have not been clarified.AIM To identify the effects of resveratrol on GC progression and explore the related molecular mechanisms.METHODS Action targets of resveratrol and GC-related targets were screened from public databases.The overlapping targets between the two were confirmed using a Venn diagram,and a“Resveratrol-Target-GC”network was constructed using Cyto-scape software version 3.9.1.The protein-protein interaction(PPI)network was constructed using STRING database and core targets were identified by PPI network analysis.The Database for Annotation,Visualization and Integrated A total of 378 resveratrol action targets and 2154 GC disease targets were obtained from public databases,and 181 intersection targets between the two were screened by Venn diagram.The top 20 core targets were identified by PPI network analysis of the overlapping targets.GO function analysis mainly involved protein binding,identical protein binding,cytoplasm,nucleus,negative regulation of apoptotic process and response to xenobiotic stimulus.KEGG enrichment analysis suggested that the involved signaling pathways mainly included PI3K-AKT signaling pathway,MAPK signaling pathway,IL-17 signaling pathway,TNF signaling pathway,ErbB signaling pathway,etc.FBJ murine osteosarcoma viral oncogene homolog(FOS)and matrix metallopeptidase 9(MMP9)were selected by differential expression analysis,and they were closely associated with immune infiltration.Molecular docking results showed that resveratrol docked well with these two targets.Resveratrol treatment arrested the cell cycle at the S phase,induced apoptosis,and weakened viability,migration and invasion in a dose-dependent manner.Furthermore,resveratrol could exhibit anti-GC effect by regulating FOS and MMP9 expression.CONCLUSION The anti-GC effects of resveratrol are related to the inhibition of cell proliferation,migration,invasion and induction of cell cycle arrest and apoptosis by targeting FOS and MMP9.

A Compact UHF Antenna Based on Hilbert Fractal Elements and a Serpentine Arrangement for Detecting Partial Discharg

Efforts to protect electric power systems from faults have commonly relied on the use of ultra-high frequency(UHF)antennas for detecting partial discharge(PD)as a common precursor to faults.However,the effectiveness of existing UHF antennas suffers from a number of challenges such as limited bandwidth,relatively large physical size,and low detection sensitivity.The present study addresses these issues by proposing a compact microstrip patch antenna with fixed dimensions of 100 mm×100 mm×1.6 mm.The results of computations yield an optimized antenna design consisting of 2nd-order Hilbert fractal units positioned within a four-layer serpentine arrangement with a fractal unit connection distance of 3.0 mm.Specifically,the optimized antenna design achieves a detection bandwidth for which the voltage standing wave ratio is less than 2 that is approximately 97.3%of the UHF frequency range(0.3–3 GHz).Finally,a prototype antenna is fabricated using standard printed circuit board technology,and the results of experiments demonstrate that the proposed antenna is capable of detecting PD signals at a distance of 8 m from the discharge source.

Study on the effect and mechanism of Swertia mussotii Franch. in the treatment of primary biliary cholangitis based on bioinformatics and in vitro experiments

Background:Primary biliary cholangitis(PBC)is a chronic biliary autoimmune liver disease characterized by intrahepatic cholestasis.Swertia mussotii Franch.(SMF)is a Tibetan medicine with hepatoprotective and anti-inflammatory activities.In this study,the therapeutic effect and potential mechanisms of SMF on PBC were investigated by bioinformatics analysis and in vitro experimental validation,with the aim of promoting the progress of SMF and PBC research.Methods:We first explored the therapeutic effects and key targets of SMF on PBC using a network pharmacology approach,further screened the core targets using the GSE79850 dataset,and finally validated the results using molecular docking techniques and in vitro experiments.Results:By bioinformatics analysis,we identified core targets of SMF for PBC treatment(STAT3,JAK2,TNF-α,and IL-1β)and important signaling pathways:JAK-STAT,TNF,and PI3K-AKT.The molecular docking results showed that the significant components of SMF had good binding properties to the core targets.In vitro experiments showed that SMF extracts improved the extent of epithelial-mesenchymal transition in human intrahepatic biliary epithelial cells and had a significant reversal effect on epithelial-mesenchymal transition process markers and potential targets in PBC.Conclusion:SMF may exert its therapeutic effects on PBC by acting on important targets such as STAT3,JAK2,TNF-α,IL-1β,Vimentin,and E-cadherin and the pathways in which they are involved.

Adaptive Variational Mode Decomposition for Bearing Fault Detection

Rolling element bearings are commonly used in rotary mechanical and electrical equipment. According to investigation, more than half of rotating machinery defects are related to bearing faults. However, reliable bearing fault detection still remains a challenging task, especially in industrial applications. The objective of this work is to propose an adaptive variational mode decomposition (AVMD) technique for non-stationary signal analysis and bearing fault detection. The AVMD includes several steps in processing: 1) Signal characteristics are analyzed to determine the signal center frequency and the related parameters. 2) The ensemble-kurtosis index is suggested to decompose the target signal and select the most representative intrinsic mode functions (IMFs). 3) The envelope spectrum analysis is performed using the selected IMFs to identify the characteristic features for bearing fault detection. The effectiveness of the proposed AVMD technique is examined by experimental tests under different bearing conditions, with the comparison of other related bearing fault techniques.

气候模式CAS-ESM-C对1月热带太平洋流场模态的模拟评估

利用气候模式CAS-ESM-C从1922年起84年的模拟资料,对1月份热带太平洋上层流场作复EOF分解及小波分析,并与实况以及理论解析解作对比讨论,以考察模式对赤道大洋上层流场的模拟能力,得到主要结论:(1)复EOF分解前3个模态的方差贡献为53.5%、12.9%、9.5%,累积方差贡献为75.9%,累积方差贡献比实况更高。(2)第一、二模态空间场与实况相比总体相像,流场都为赤道所俘获,在俘获区内的流场均以偏纬向流为主;差异在于模拟资料分析的赤道俘获区范围较实况要大,流场的经向流分量及越赤道流也较实况明显。(3)第一、二模态实时间系数序列无线性变化趋势,而实况则有。复EOF模态年际及年代际变化与实况相同或相近;第一、二模态中3~7年的年际变化是厄尔尼诺与南方涛动(ENSO)的反映;第一模态22~23年的年代际变化受北太平洋主要气候模态北太平洋年代际振荡(PDO)对热带太平洋的影响,而第二模态13年的年代际变化是受北太平洋次要气候模态北太平洋环流振荡(NPGO)对热带太平洋的影响;第一、二模态还都有峰值16年的年代际变化,这可能与印尼穿越流有关。(4)模拟资料分析的结果具有理论解析解中流场为赤道所俘获及流场为纬向流的特点,只是解析解中因无风应力强迫,流场呈纯纬向流。(5)第一(二)模态在赤道太平洋东部(中部)有海温动力异常,并可称之为东(中)部型ENSO模态。气候模式CAS-ESM-C对热带太平洋上层流场的模拟表现较佳。

DC active power filter based on model predictive control for DC bus overvoltage suppression of accelerator grid power supply

The China Fusion Engineering Test Reactor plans to build a 200 k V/25 A acceleration grid power supply(AGPS)for the negative-ion-based neutral beam injector prototype system.The AGPS uses a rectifier-inverter-isolated step-up structure.There is a DC bus between the rectifier and the inverter.In order to limit DC bus voltage ripple and transient fluctuations,a large number of capacitors are used,which degrades the reliability of the power supply and occupies a large amount of space.This work finds that due to the difference in the turn-off time of the rectifier and the inverter,the capacitance mainly depends on the rectifier current when the inverter is turned off.On this basis,an active power filter(APF)scheme is proposed to absorb the current.To enhance the dynamic response ability of the APF,model predictive control is adopted.In this paper,the circuit structure of the APF is introduced,the prediction model is deduced,the corresponding control strategy and signal detection method are proposed,and the simulation and experimental results show that APF can track the transient current of the DC bus and reduce the voltage fluctuation significantly.

A Whale Optimization Algorithm with Distributed Collaboration and Reverse Learning Ability

Due to the development of digital transformation,intelligent algorithms are getting more and more attention.The whale optimization algorithm(WOA)is one of swarm intelligence optimization algorithms and is widely used to solve practical engineering optimization problems.However,with the increased dimensions,higher requirements are put forward for algorithm performance.The double population whale optimization algorithm with distributed collaboration and reverse learning ability(DCRWOA)is proposed to solve the slow convergence speed and unstable search accuracy of the WOA algorithm in optimization problems.In the DCRWOA algorithm,the novel double population search strategy is constructed.Meanwhile,the reverse learning strategy is adopted in the population search process to help individuals quickly jump out of the non-ideal search area.Numerical experi-ments are carried out using standard test functions with different dimensions(10,50,100,200).The optimization case of shield construction parameters is also used to test the practical application performance of the proposed algo-rithm.The results show that the DCRWOA algorithm has higher optimization accuracy and stability,and the convergence speed is significantly improved.Therefore,the proposed DCRWOA algorithm provides a better method for solving practical optimization problems.

Clinical Application of Double Ovulation Stimulation in Patients with Diminished Ovarian Reserve and Asynchronous Follicular Development Undergoing Assisted Reproduction Technology

Objective This study aimed to compare the clinical effects of double ovulation stimulation(DouStim)applied during the follicular and luteal phases with the antagonist protocol in patients with diminished ovarian reserve(DOR)and asynchronous follicular development undergoing assisted reproductive technology(ART).Methods The clinical data of patients with DOR and asynchronous follicular development receiving ART from January 2020 to December 2021 were retrospectively analyzed.The patients were divided into two groups according to their ovulation stimulation protocol:DouStim group(n=30)and antagonist group(n=62).Assisted reproduction and clinical pregnancy outcomes were compared between the two groups.Results In the DouStim group,the number of oocytes retrieved,metaphase II(MII)oocytes,two-pronuclei(2PN),day 3(D3)embryos,D3 high-quality embryos as well as blastocyst formation,implantation,and human chorionic gonadotropin-positive rates were significantly greater than those in the antagonist group(all P<0.05).No significant differences were found in MII,fertilization,or continued pregnancy rates at the first frozen embryo transfer(FET),in-vitro fertilization(IVF)cancellation,or early medical abortion rates between the groups(all P>0.05).Except for the early medical abortion rate,the DouStim group generally had favorable outcomes.In the DouStim group,the dosage and duration of gonadotropin and the fertilization rate were significantly greater in the first ovulation stimulation induction than in the second ovulation stimulation induction(P<0.05).Conclusion The DouStim protocol efficiently and economically obtained more mature oocytes and high-quality embryos for patients with DOR and asynchronous follicular development.

海上风电作业窗口期管理研究与系统开发

因海洋环境的复杂性,海上风电在施工、运行、维护等方面面临着众多挑战,研究与开发海上风电作业窗口期管理系统,可降低作业风险、提高作业效率、节约作业成本。本文首先总结了窗口期管理的需求现状,从作业工序、气象水文两方面分析了影响海上风电窗口期的要素,然后以基建期需求为目标,效率优先为策略,提出了多要素窗口期管理模型,开发了海上风电作业窗口期管理系统,实现了气象水文预报及窗口期精细化管理,最后,对系统的功能及应用效果做了简要介绍。

Advances in deciphering salt tolerance mechanism in maize

Maize(Zea mays L.)is a global cereal crop whose demand is projected to double by 2050.Along with worsening of farmland salinization,salt stress has become a major environmental threat to the sustainability of maize production worldwide.Accordingly,there is an urgent need to decipher salt-tolerant mechanisms and facilitate the breeding of salt-tolerant maize.As salt tolerance is a complex trait regulated by multiple genes,and maize germplasm varies widely in salt tolerance,efforts have been devoted to the identification and application of quantitative-trait loci(QTL)for salt tolerance.QTL associated with ion regulation,osmotic tolerance,and other aspects of salt tolerance have been discovered using genomewide association studies(GWAS),linkage mapping,and omics-based approaches.This review highlights recent advances in the molecular-level understanding of salt stress response in maize,in particular in(a)the discovery of salt-tolerance QTL,(b)the mechanisms of salt tolerance,(c)the development of salttolerant maize cultivars,and(d)current challenges and future prospects.

Suppression and compensation effect of oxygen on the behavior of heavily boron-doped diamond films

This work investigates the suppression and compensation effect of oxygen on the behaviors and characteristics of heavily boron-doped microwave plasma chemical vapor deposition(MPCVD)diamond films.The suppression effect of oxygen on boron incorporation is observed by an improvement in crystal quality when oxygen is added during the diamond doping process.A relatively low hole concentration is expected and verified by Hall effect measurements due to the compensation effect of oxygen as a deep donor in diamond.A low acceptor concentration,high compensation donor concentration and relatively larger acceptor ionization energy are then induced by the incorporation of oxygen;however,a heavily boron-doped diamond film with high crystal quality can also be expected.The formation of an oxygen–boron complex structure instead of oxygen substitution,as indicated by the results of x-ray photoelectron spectroscopy,is suggested to be more responsible for the observed enhanced compensation effect due to its predicted low formation energy.Meanwhile,density functional theory calculations show that the boron–oxygen complex structure is easily formed in diamond with a formation energy of-0.83 eV.This work provides a comprehensive understanding of oxygen compensation in heavily boron-doped diamond.

Multi-point discharge model: study on corona discharge of double-ended needle in large space

Corona discharge, as a common means to obtain non-equilibrium plasma, can generally obtain high-concentration plasma by increasing discharge points to meet production needs. However,the existing numerical simulation models used to study multi-point corona discharge are all calculations of small-scale space models, which cannot obtain the distribution characteristics of plasma in large space. Based on our previous research, this paper proposes a hybrid model for studying the distribution of multi-point discharge plasma in large-scale spaces, which divides the computational domain and computes separately with the hydrodynamic model and the ion mobility model. The simulation results are verified by a needle–ball electrode device. Firstly, the electric field distribution and plasma distribution of the needle electrodes with single tip and double tips are compared and discussed. Secondly, the plasma distribution of the needle electrode with the double tip at different voltages is investigated. Both computational and experimental results indicate that the charged particle concentration and current of the needle electrode with double tips are both twice as high as those of the needle electrode with a single tip. This model can extend the computational area of the multi-point corona discharge finite element model to the sub-meter(25 cm) or meter level, which provides an effective means to study the plasma distribution generated by multiple discharge points in large-scale space.

Study on the interaction mechanism of double-blade corona discharge with a large discharge gap

Multi-source corona discharge is a commonly used method to generate more charged particles,but the interaction mechanism between multiple discharge sources,which largely determines the overall discharge effect,has still not been studied much.In this work,a large-space hybrid model based on a hydrodynamic model and ion-transport model is adopted to study the interaction mechanism between discharge sources.Specifically,the effects of the number of electrodes,voltage level,and electrode spacing on the discharge characteristics are studied by taking a double-blade electrode as an example.The calculation results show that,when multiple discharge electrodes operate simultaneously,the superimposed electric field includes multiple components from the electrodes,making the ion distribution and current different from that under a single-blade electrode.The larger the distance between discharge electrodes,the weaker the interaction.When the electrode spacing d is larger than 4 cm,the interaction can be ignored.The results can guide the design of large discharge gap array electrodes to achieve efficient discharge.

Pre-transjugular-intrahepatic-portosystemic-shunt measurement of hepatic venous pressure gradient and its clinical application: A comparison study

BACKGROUND It is controversial whether transjugular intrahepatic portosystemic shunt(TIPS)placement can improve long-term survival.AIM To assess whether TIPS placement improves survival in patients with hepaticvenous-pressure-gradient(HVPG)≥16 mmHg,based on HVPG-related risk stratification.METHODS Consecutive variceal bleeding patients treated with endoscopic therapy+nonselectiveβ-blockers(NSBBs)or covered TIPS placement were retrospectively enrolled between January 2013 and December 2019.HVPG measurements were performed before therapy.The primary outcome was transplant-free survival;secondary endpoints were rebleeding and overt hepatic ence-phalopathy(OHE).RESULTS A total of 184 patients were analyzed(mean age,55.27 years±13.86,107 males;102 in the EVL+NSBB group,82 in the covered TIPS group).Based on the HVPG guided risk stratification,70 patients had HVPG<16 mmHg,and 114 patients had HVPG≥16 mmHg.The median follow-up time of the cohort was 49.5 mo.There was no significant difference in transplant-free survival between the two treatment groups overall(hazard ratio[HR],0.61;95%confidence interval[CI]:0.35-1.05;P=0.07).In the high-HVPG tier,transplant-free survival was higher in the TIPS group(HR,0.44;95%CI:0.23-0.85;P=0.004).In the low-HVPG tier,transplantfree survival after the two treatments was similar(HR,0.86;95%CI:0.33-0.23;P=0.74).Covered TIPS placement decreased the rate of rebleeding independent of the HVPG tier(P<0.001).The difference in OHE between the two groups was not statistically significant(P=0.09;P=0.48).CONCLUSION TIPS placement can effectively improve transplant-free survival when the HVPG is greater than 16 mmHg.

Preparation of Eco-Friendly High-Performance Manganese Dioxide Supercapacitors by Linear Sweep Voltammetry

In this paper,the non-polluting,non-toxic,and eco-friendly material-MnO_(2)electrodes were deposited on three-dimensional porous nickel(Ni)foam by linear sweep voltammetry,and the entire electrodeposition process did not require sintering of the material,which was fast and convenient while avoiding unnecessary energy consump-tion and thus was environmentally friendly.Scanning electron microscopy(SEM)and transmission electron microscopy were used to examine the surface and microscopic characteristics of each sample(TEM).Chronoam-perometry(CA),cyclic voltammetry(CV),galvanostatic charge/discharge(GCD),and electrochemical impedance spectroscopy(EIS)were then used to determine the electrochemical characteristics of the manufactured samples.The result suggests that the MnO_(2)-sv80 electrode sample at a scan rate of 80 mV/s^(−1)has excellent performance for the supercapacitor electrode.The specific capacitance was as high as 531.4 F g^(−1)at a current density of 1 A g^(−1)and remained at 223.2 F g^(−1)at an ultra-high current density of 20 A g^(−1),with capacitance retention of 42%.

Disruption prediction based on fusion feature extractor on J-TEXT

Predicting disruptions across different tokamaks is necessary for next generation device.Future large-scale tokamaks can hardly tolerate disruptions at high performance discharge,which makes it difficult for current data-driven methods to obtain an acceptable result.A machine learning method capable of transferring a disruption prediction model trained on one tokamak to another is required to solve the problem.The key is a feature extractor which is able to extract common disruption precursor traces in tokamak diagnostic data,and can be easily transferred to other tokamaks.Based on the concerns above,this paper presents a deep feature extractor,namely,the fusion feature extractor(FFE),which is designed specifically for extracting disruption precursor features from common diagnostics on tokamaks.Furthermore,an FFE-based disruption predictor on J-TEXT is demonstrated.The feature extractor is aimed to extracting disruption-related precursors and is designed according to the precursors of disruption and their representations in common tokamak diagnostics.Strong inductive bias on tokamak diagnostics data is introduced.The paper presents the evolution of the neural network feature extractor and its comparison against general deep neural networks,as well as a physics-based feature extraction with a traditional machine learning method.Results demonstrate that the FFE may reach a similar effect with physics-guided manual feature extraction,and obtain a better result compared with other deep learning methods.

A novel approach for 25-gauge transconjunctival sutureless vitrectomy to evaluate vitreous substitutes in rabbits

AIM:To improve the standard three-port vitrectomy for establishing and evaluating an endotamponade model in rabbits.METHODS:Three ports were prepared near the third eyelid of rabbits,and the infusion port was placed at the inferior nasal quadrant with the inserted cannula linking with a self-designed handheld rigid infusion catheter.All right eyes of rabbits underwent a modified 25-gauge vitrectomy and were subsequently filled with balanced salt solution,silicone oil,and eight-arm polyethylene glycols(8-arm PEGs)hydrogel separately for comparison.Ophthalmic examinations were performed regularly to record the changes after the surgery.RESULTS:Successful vitrectomy was achieved among 44 chinchilla rabbits.The mean operation time was 4.51±1.25min.Four eyes(9.1%)presented limited lens touch and two eyes(4.5%)showed retinal touch during surgery.Incision leakage was found in three eyes(6.8%)after surgery.There was no endophthalmitis,hemorrhage,or retinal detachment during the observation period and ophthalmic examinations after the implantation of vitreous substitutes.CONCLUSION:The modified technique of the standard vitrectomy applied in the endotamponade model in rabbits shows excellent safety and practicality.