基于声发射Ib值分析的渗铝321钢损伤特性研究

太阳能热发电换热管主要材料渗铝321钢的损伤会导致换热管的寿命缩短甚至断裂,因此必须进行损伤检测。采用声发射方法对渗铝321钢的损伤特性进行分析,实现对换热管性能的在线动态监测。通过采用声发射Ib值特征来表征渗铝321钢的损伤程度,并运用自组织映射(SOM)神经网络算法进行声发射特征参数聚类,以分析材料的损伤模式。结果表明,力学塑性阶段的声发射事件数量剧增,能量和振铃计数的峰值标志着试件的断裂。此外,在试件失效前,Ib值显著降低且密度变密集,表明Ib值的变化特征可以作为材料临界失效的预警信号。通过SOM算法对特征参数进行聚类分析得到4个簇及其对应的特征频率,并使用扫描电子显微镜(SEM)观察试件的断口形貌,得出4个簇分别对应于孔洞生长与汇合、微裂纹成核、宏观裂纹扩展和纤维状断裂4类损伤模式。这项研究旨在探索金属管材的损伤演化行为,并为管材的损伤分析和健康监测提供依据。

Microwave shock motivating the Sr substitution of 2D porous GdFeO_(3) perovskite for highly active oxygen evolution

The incorporation of partial A-site substitution in perovskite oxides represents a promising strategy for precisely controlling the electronic configuration and enhancing its intrinsic catalytic activity.Conventional methods for A-site substitution typically involve prolonged high-temperature processes.While these processes promote the development of unique nanostructures with highly exposed active sites,they often result in the uncontrolled configuration of introduced elements.Herein,we present a novel approach for synthesizing two-dimensional(2D)porous GdFeO_(3) perovskite with A-site strontium(Sr)substitution utilizing microwave shock method.This technique enables precise control of the Sr content and simultaneous construction of 2D porous structures in one step,capitalizing on the advantages of rapid heating and cooling(temperature~1100 K,rate~70 K s^(-1)).The active sites of this oxygen-rich defect structure can be clearly revealed through the simulation of the electronic configuration and the comprehensive analysis of the crystal structure.For electrocatalytic oxygen evolution reaction application,the synthesized 2D porous Gd_(0.8)Sr_(0.2)FeO_(3) electrocatalyst exhibits an exceptional overpotential of 294 mV at a current density of 10 mA cm^(-2)and a small Tafel slope of 55.85 mV dec^(-1)in alkaline electrolytes.This study offers a fresh perspective on designing crystal configurations and the construction of nanostructures in perovskite.

Microstructure and thermal properties of dissimilar M300–CuCr1Zr alloys by multi-material laser-based powder bed fusion

Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.

Colon and rectal cancer:An emergent public health problem

Colorectal cancer ranks third globally,with a high mortality rate.In the United States,and different countries in Europe,organized population screenings exist and include people between 50 and 74 years of age.These screenings have allowed an early diagnosis and consequently an improvement in health indicators.Colon and rectal cancer(CRC)is a disease of particular interest due to the high global burden associated with it and the role attributed to prevention and early diagnosis in reducing morbidity and mortality.This study is a review of CRC pathology and includes the most recent scientific evidence regarding this pathology,as well as a diagnosis of the epidemiological situation of CRC.Finally,the recommendation from a public health perspective will be discussed in detail taking into account the context and the most current recommendations.

氧化石墨烯/热还原氧化石墨烯改性砂浆的力学/电学性能研究

研究了热还原氧化石墨烯(TRGO)和氧化石墨烯(GO)在水泥砂浆环境下的分散机理,探索了这两种导电相的单掺和复掺对砂浆力学/电学性能的影响。研究表明GO对TRGO在富钙高碱环境下的分散有促进作用,且分散最佳质量比(%)为3∶10;与TRGO单掺相比,复掺GO能促进砂浆水化产物形成片状结构并互相交织,使得力学性能显著提升,当w(GO)∶w(TRGO)=0.3∶1.0时,28 d抗折强度和抗压强度与单掺TRGO相比提升了21.34%和34.52%,随着掺量增加力学性能反而下降;水泥砂浆的电导率随着GO与TRGO导电相的增加而增大,当w(GO)∶w(TRGO)=0.12∶0.4时,28 d龄期试件的电阻率呈现突变现象,表明该体系出现渗滤阈值;保持分散最佳比例下当TRGO大于0.7%(质量分数)之后,增加掺量对电阻率的影响趋于平缓且走低的趋势,表明TRGO掺量0.7%(质量分数)为试件电阻率的添加阈值。

双稳态压电-电磁复合俘能器非线性动力学分析

提出一种基于聚偏氟乙烯(PVDF)压电材料的双稳态悬臂梁式压电-电磁复合俘能器结构。考虑到大变形时材料的几何非线性特点,基于Euler-Bernoulli梁理论和Hamilton原理建立系统分布式参数模型,采用Galerkin法与谐波平衡法给出响应解析解;利用MATLAB仿真分析激励频率、激励幅值、磁铁间距和负载电阻对系统输出性能的影响,并运用龙格-库塔法分析俘能器的非线性动力学特性;通过电路仿真研究悬臂梁在不同振动状态下的整流滤波特性。结果表明:随着激励幅值的提高,系统阱间运动的频率带宽会逐渐增大;存在一组最优的压电负载和电磁负载,使得系统输出总功率达到最大;负载的改变不会影响阱间运动的频带宽度;随着激励的增强,系统在混沌运动和周期运动间进行状态转换,可以利用标准桥式整流滤波电路进行周期运动时的能量采集,但该电路无法稳定收集混沌运动时的系统输出。

Multi-layer perceptron-based data-driven multiscale modelling of granular materials with a novel Frobenius norm-based internal variable

One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVPs).In the family of ML models,recurrent neural networks(RNNs)have been extensively applied to capture history-dependent constitutive responses of granular materials,but these multiple-step-based neural networks are neither sufficiently efficient nor aligned with the standard finite element method(FEM).Single-step-based neural networks like the multi-layer perceptron(MLP)are an alternative to bypass the above issues but have to introduce some internal variables to encode complex loading histories.In this work,one novel Frobenius norm-based internal variable,together with the Fourier layer and residual architectureenhanced MLP model,is crafted to replicate the history-dependent constitutive features of representative volume element(RVE)for granular materials.The obtained ML models are then seamlessly embedded into the FEM to solve the BVP of a biaxial compression case and a rigid strip footing case.The obtained solutions are comparable to results from the FEM-DEM multiscale modelling but achieve significantly improved efficiency.The results demonstrate the applicability of the proposed internal variable in enabling MLP to capture highly nonlinear constitutive responses of granular materials.

A particle-resolved heat-particle-fluid coupling model by DEM-IMB-LBM

Multifield coupling is frequently encountered and also an active area of research in geotechnical engineering.In this work,a particle-resolved direct numerical simulation(PR-DNS)technique is extended to simulate particle-fluid interaction problems involving heat transfer at the grain level.In this extended technique,an immersed moving boundary(IMB)scheme is used to couple the discrete element method(DEM)and lattice Boltzmann method(LBM),while a recently proposed Dirichlet-type thermal boundary condition is also adapted to account for heat transfer between fluid phase and solid particles.The resulting DEM-IBM-LBM model is robust to simulate moving curved boundaries with constant temperature in thermal flows.To facilitate the understanding and implementation of this coupled model for non-isothermal problems,a complete list is given for the conversion of relevant physical variables to lattice units.Then,benchmark tests,including a single-particle sedimentation and a two-particle drafting-kissing-tumbling(DKT)simulation with heat transfer,are carried out to validate the accuracy of our coupled technique.To further investigate the role of heat transfer in particle-laden flows,two multiple-particle problems with heat transfer are performed.Numerical examples demonstrate that the proposed coupling model is a promising high-resolution approach for simulating the heat-particle-fluid coupling at the grain level.

An MPI parallel DEM-IMB-LBM framework for simulating fluid-solid interaction problems

The high-resolution DEM-IMB-LBM model can accurately describe pore-scale fluid-solid interactions,but its potential for use in geotechnical engineering analysis has not been fully unleashed due to its prohibitive computational costs.To overcome this limitation,a message passing interface(MPI)parallel DEM-IMB-LBM framework is proposed aimed at enhancing computation efficiency.This framework utilises a static domain decomposition scheme,with the entire computation domain being decomposed into multiple subdomains according to predefined processors.A detailed parallel strategy is employed for both contact detection and hydrodynamic force calculation.In particular,a particle ID re-numbering scheme is proposed to handle particle transitions across sub-domain interfaces.Two benchmarks are conducted to validate the accuracy and overall performance of the proposed framework.Subsequently,the framework is applied to simulate scenarios involving multi-particle sedimentation and submarine landslides.The numerical examples effectively demonstrate the robustness and applicability of the MPI parallel DEM-IMB-LBM framework.

Contribution of glial cells to the neuroprotective effects triggered by repetitive magnetic stimulation:a systematic review

Repetitive transcranial magnetic stimulation has been increasingly studied in different neurological diseases,and although most studies focus on its effects on neuronal cells,the contribution of nonneuronal cells to the improvement trigge red by repetitive transcranial magnetic stimulation in these diseases has been increasingly suggested.To systematically review the effects of repetitive magnetic stimulation on non-neuronal cells two online databases.Web of Science and PubMed were searched fo r the effects of high-frequency-repetitive transcranial magnetic stimulation,low-frequencyrepetitive transcranial magnetic stimulation,intermittent theta-bu rst stimulation,continuous thetaburst stimulation,or repetitive magnetic stimulation on non-neuronal cells in models of disease and in unlesioned animals or cells.A total of 52 studies were included.The protocol more frequently used was high-frequency-repetitive magnetic stimulation,and in models of disease,most studies report that high-frequency-repetitive magnetic stimulation led to a decrease in astrocyte and mic roglial reactivity,a decrease in the release of pro-inflammatory cyto kines,and an increase of oligodendrocyte proliferation.The trend towards decreased microglial and astrocyte reactivity as well as increased oligodendrocyte proliferation occurred with intermittent theta-burst stimulation and continuous theta-burst stimulation.Few papers analyzed the low-frequency-repetitive transcranial magnetic stimulation protocol,and the parameters evaluated were restricted to the study of astrocyte reactivity and release of pro-inflammatory cytokines,repo rting the absence of effects on these paramete rs.In what concerns the use of magnetic stimulation in unlesioned animals or cells,most articles on all four types of stimulation reported a lack of effects.It is also important to point out that the studies were developed mostly in male rodents,not evaluating possible diffe rential effects of repetitive transcranial magnetic stimulation between sexes.This systematic review supports that thro ugh modulation of glial cells repetitive magnetic stimulation contributes to the neuroprotection or repair in various neurological disease models.Howeve r,it should be noted that there are still few articles focusing on the impact of repetitive magnetic stimulation on non-neuronal cells and most studies did not perform in-depth analyses of the effects,emphasizing the need for more studies in this field.

Classifying rockburst with confidence:A novel conformal prediction approach

The scientific community recognizes the seriousness of rockbursts and the need for effective mitigation measures.The literature reports various successful applications of machine learning(ML)models for rockburst assessment;however,a significant question remains unanswered:How reliable are these models,and at what confidence level are classifications made?Typically,ML models output single rockburst grade even in the face of intricate and out-of-distribution samples,without any associated confidence value.Given the susceptibility of ML models to errors,it becomes imperative to quantify their uncertainty to prevent consequential failures.To address this issue,we propose a conformal prediction(CP)framework built on traditional ML models(extreme gradient boosting and random forest)to generate valid classifications of rockburst while producing a measure of confidence for its output.The proposed framework guarantees marginal coverage and,in most cases,conditional coverage on the test dataset.The CP was evaluated on a rockburst case in the Sanshandao Gold Mine in China,where it achieved high coverage and efficiency at applicable confidence levels.Significantly,the CP identified several“confident”classifications from the traditional ML model as unreliable,necessitating expert verification for informed decision-making.The proposed framework improves the reliability and accuracy of rockburst assessments,with the potential to bolster user confidence.

Safety for all temperature zinc-ion batteries

Zinc-ion batteries(ZIBs)have emerged as a promising candidate in the grid scale energy storage,offering an alternative to conventional lithium-ion batteries.However,as research and development efforts in this field progress,it becomes increasingly important to address potential hazards associated with flammable gases and electrolyte components.This future paper aims to raise awareness of safety issues that may be overlooked and underscore two primary temperature-induced hazards:long-term cycling H_(2) gas accu-mulation and flammable organic solvents.We evaluate various electrolytes aimed at minimizing gas pro-duction and improving high-temperature adaptability.Particularly,we emphasize the effectiveness of electrolyte modifications,especially co-solvent approach in addressing the above safety concerns and suggest pathways for formulating practical safe electrolytes.Notably,apart from examining the inherent electrochemical stability window(EsW)of the electrolyte,we urge consideration of side reaction prod-ucts on electrode interfaces and high temperatures as factors influencing a battery's EsW.

Microwave-assisted exploration of the electron configuration-dependent electrocatalytic urea oxidation activity of 2D porous NiCo_(2)O_(4) spinel

Urea holds promise as an alternative water-oxidation substrate in electrolytic cells.High-valence nickelbased spinel,especially after heteroatom doping,excels in urea oxidation reactions(UOR).However,traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision,hindering the balance between controlled doping and highly active two-dimensional(2D)porous structures design.This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels.Herein,we present a microwave shock method for the preparation of 2D porous NiCo_(2)O_(4)spinel.Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design,non-metal doping(boron,phosphorus,and sulfur)with distinct extranuclear electron disparities serves as straightforward examples for investigation.Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo_(2)O_(4)structural stability.The introduced defect levels induce unpaired d-electrons in transition metals,enhancing the adsorption of electron-donating amino groups in urea molecules.Simultaneously,Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity.The prepared phosphorus-doped 2D porous NiCo_(2)O_(4),with optimal electron configuration control,outperforms most reported spinels.This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.

Millimetric devices for nerve stimulation:a promising path towards miniaturization

Nerve stimulation is a rapidly developing field,demonstrating positive outcomes across several conditions.Despite potential benefits,current nerve stimulation devices are large,complicated,and are powered via implanted pulse generators.These facto rs necessitate invasive surgical implantation and limit potential applications.Reducing nerve stimulation devices to millimetric sizes would make these interventions less invasive and facilitate broader therapeutic applications.However,device miniaturization presents a serious engineering challenge.This review presents significant advancements from several groups that have overcome this challenge and developed millimetricsized nerve stimulation devices.These are based on antennas,mini-coils,magneto-electric and optoelectronic materials,or receive ultrasound power.We highlight key design elements,findings from pilot studies,and present several considerations for future applications of these devices.

New avenues for the treatment of immunotherapy-resistant pancreatic cancer

Pancreatic cancer(PC)is characterized by its extremely aggressive nature and ranks 14th in the number of new cancer cases worldwide.However,due to its complexity,it ranks 7th in the list of the most lethal cancers worldwide.The pathogenesis of PC involves several complex processes,including familial genetic factors associated with risk factors such as obesity,diabetes mellitus,chronic pancreatitis,and smoking.Mutations in genes such as KRAS,TP53,and SMAD4 are linked to the appearance of malignant cells that generate pancreatic lesions and,consequently,cancer.In this context,some therapies are used for PC,one of which is immunotherapy,which is extremely promising in various other types of cancer but has shown little response in the treatment of PC due to various resistance mechanisms that contribute to a drop in immunotherapy efficiency.It is therefore clear that the tumor microenvironment(TME)has a huge impact on the resistance process,since cellular and non-cellular elements create an immunosuppressive environment,characterized by a dense desmoplastic stroma with cancerassociated fibroblasts,pancreatic stellate cells,extracellular matrix,and immunosuppressive cells.Linked to this are genetic mutations in TP53 and immunosuppressive factors that act on T cells,resulting in a shortage of CD8+T cells and limited expression of activation markers such as interferon-gamma.In this way,finding new strategies that make it possible to manipulate resistance mechanisms is necessary.Thus,techniques such as the use of TME modulators that block receptors and stromal molecules that generate resistance,the use of genetic manipulation in specific regions,such as microRNAs,the modulation of extrinsic and intrinsic factors associated with T cells,and,above all,therapeutic models that combine these modulation techniques constitute the promising future of PC therapy.Thus,this study aims to elucidate the main mechanisms of resistance to immunotherapy in PC and new ways of manipulating this process,resulting in a more efficient therapy for cancer patients and,consequently,a reduction in the lethality of this aggressive cancer.

颗粒材料破碎行为数值分析方法研究综述

颗粒材料在自然界和工程领域普遍存在,外载荷作用下颗粒可能发生破碎现象.颗粒材料的破碎行为会引起其物理力学性质的变化,给工程和建筑建设带来极大影响.研究宏、细观尺度下颗粒材料的破碎行为不仅可以揭示颗粒破碎的力学机理,还对工程领域的安全和正常进行提供保障.因此,分析颗粒破碎过程既具有实际工程意义,又有理论研究价值.文章综述了颗粒破碎行为研究的数值分析方法,在基于离散元法理论的数值方法中,介绍了黏结-破碎法和碎片替代法;在基于离散元-有限元耦合算法的方法中,介绍了比例边界有限元法、组合有限元-离散元法和内聚力模型;此外还详细介绍了近场动力学方法.文章主要梳理并讨论了以上数值方法的提出、实现过程、发展、关键问题、优势以及这些方法的不足之处.此外,针对每一种数值方法回顾了国内外的研究成果以及在工程中的主要应用,对每种方法重点关注的问题进行了介绍.最后对目前关于颗粒破碎的数值研究进行总结,并对今后的发展方向进行简单的展望.

护理干预促进慢性呼吸困难患者自我管理的研究进展:整合性综述

目的旨在通过系统综述,确定针对复杂慢性病患者增强自我管理的干预措施,以改善慢性呼吸困难,为护理人员促进该类人群的自我管理提供依据。方法2023年12月,系统检索Medline、Scopus、Web of Science、CINAHL、Cochrane图书馆和乔安娜布里格斯研究所(Joanna Briggs Institute,JBI)循证实践数据库。对纳入研究进行数据提取和综合,研究人员采用Rayyan文献管理软件筛选标题及摘要,并依据JBI研究质量评估工具进行方法学质量评估。结果共纳入18项研究。这些研究探讨了针对慢性呼吸困难的各种干预措施,包括药物干预(氧气疗法和吸入疗法)和非药物方法(教育计划、呼吸练习、液体摄入管理、身体感知技术、同伴支持、情商培训和网络应用程序的使用)。这些干预措施减轻了患者情绪困扰,可以使患者在自我管理方面变得独立自主。结论促进复杂慢性病患者对慢性呼吸困难的自我管理需要采取综合方法,但目前研究中没有充分考虑到针对患者行为改变的干预措施,需要进一步开展相关研究完善干预措施。

Urea breath test for Helicobacter pylori infection in adult dyspeptic patients: A meta-analysis of diagnostic test accuracy

BACKGROUND Helicobacter pylori(H.pylori)infection has been well-established as a significant risk factor for several gastrointestinal disorders.The urea breath test(UBT)has emerged as a leading non-invasive method for detecting H.pylori.Despite numerous studies confirming its substantial accuracy,the reliability of UBT results is often compromised by inherent limitations.These findings underscore the need for a rigorous statistical synthesis to clarify and reconcile the diagnostic accuracy of the UBT for the diagnosis of H.pylori infection.AIM To determine and compare the diagnostic accuracy of 13C-UBT and 14C-UBT for H.pylori infection in adult patients with dyspepsia.METHODS We conducted an independent search of the PubMed/MEDLINE,EMBASE,and Cochrane Central databases until April 2022.Our search included diagnostic accuracy studies that evaluated at least one of the index tests(^(13)C-UBT or ^(14)C-UBT)against a reference standard.We used the QUADAS-2 tool to assess the methodo-logical quality of the studies.We utilized the bivariate random-effects model to calculate sensitivity,specificity,positive and negative test likelihood ratios(LR+and LR-),as well as the diagnostic odds ratio(DOR),and their 95%confidence intervals.We conducted subgroup analyses based on urea dosing,time after urea administration,and assessment technique.To investigate a possible threshold effect,we conducted Spearman correlation analysis,and we generated summary receiver operating characteristic(SROC)curves to assess heterogeneity.Finally,we visually inspected a funnel plot and used Egger’s test to evaluate publication bias.endorsing both as reliable diagnostic tools in clinical practice.CONCLUSION In summary,our study has demonstrated that ^(13)C-UBT has been found to outperform the ^(14)C-UBT,making it the preferred diagnostic approach.Additionally,our results emphasize the significance of carefully considering urea dosage,assessment timing,and measurement techniques for both tests to enhance diagnostic precision.Nevertheless,it is crucial for researchers and clinicians to evaluate the strengths and limitations of our findings before implementing them in practice.

A Hierarchical Method for Locating the Interferometric Fringes of Celestial Sources in the Visibility Data

In source detection in the Tianlai project,locating the interferometric fringe in visibility data accurately will influence downstream tasks drastically,such as physical parameter estimation and weak source exploration.Considering that traditional locating methods are time-consuming and supervised methods require a great quantity of expensive labeled data,in this paper,we first investigate characteristics of interferometric fringes in the simulation and real scenario separately,and integrate an almost parameter-free unsupervised clustering method and seeding filling or eraser algorithm to propose a hierarchical plug and play method to improve location accuracy.Then,we apply our method to locate single and multiple sources’interferometric fringes in simulation data.Next,we apply our method to real data taken from the Tianlai radio telescope array.Finally,we compare with unsupervised methods that are state of the art.These results show that our method has robustness in different scenarios and can improve location measurement accuracy effectively.

Immune pathway through endometriosis to ovarian cancer

Endometriosis is an estrogen-dependent inflammatory disease,defined by the presence of functional endometrial tissue outside of the uterine cavity.This disease is one of the main gynecological diseases,affecting around 10%-15%women and girls of reproductive age,being a common gynecologic disorder.Although endometriosis is a benign disease,it shares several characteristics with invasive cancer.Studies support that it has been linked with an increased chance of developing endometrial ovarian cancer,representing an earlier stage of neoplastic processes.This is particularly true for women with clear cell carcinoma,low-grade serous carcinoma and endometrioid.However,the carcinogenic pathways between both pathologies remain poorly understood.Current studies suggest a connection between endometriosis and endometriosis-associated ovarian cancers(EAOCs)via pathways associated with oxidative stress,inflammation,and hyperestrogenism.This article aims to review current data on the molecular events linked to the development of EAOCs from endometriosis,specifically focusing on the complex relationship between the immune response to endometriosis and cancer,including the molecular mechanisms and their ramifications.Examining recent developments in immunotherapy and their potential to boost the effectiveness of future treatments.