华北板块北缘东段稀有-稀土成矿作用综述

华北克拉通北缘东段稀有-稀土矿产资源主要分布在板块边缘或不同时代的构造接合处,受郯庐断裂带、索伦-西拉木伦-长春-延吉断裂带等区域性大断裂控制,主要经历了吕梁期、印支期和燕山期等3期的构造-岩浆事件.区内的稀有-稀土矿产与中元古代和中生代岩浆岩关系密切.目前,研究区内已发现稀有-稀土矿床或矿点10余处,主要分布于辽宁省和内蒙古东部地区,成矿类型以碱性花岗岩-碱性岩型为主,伟晶岩型次之.区内稀有-稀土成矿均与碱性岩浆作用有关,成矿岩体的年代学研究表明,成矿作用可分为3个阶段,即燕山期的120~140 Ma、印支期的200~230 Ma以及与吕梁运动有关的2500~2510 Ma.本区稀有-稀土元素富集成矿过程主要与碱性岩浆的高度演化密切相关,在水和挥发分作用下,岩浆强烈分异结晶,导致成矿元素迁移聚集,随着温度、压力等成矿条件的变化,含矿流体在岩浆作用晚期随着主要造岩矿物的晶出而富集成矿.

国际焊接质量体系研究进展

国际焊接质量体系在中国的应用与推广已有20余年的历史,已涵盖轨道交通、工程机械、能源装备、冶金设备、化工设备、航空航天、船舶等诸多大型装备制造行业,为装备制造业高质量发展起到了良好的助力作用。针对国际焊接质量体系在中国的发展现状进行研究,涵盖国际焊接质量标准体系的最新动态、国际焊接质量体系在国内的发展特质和趋势,并就存在的问题进行剖析,为未来进一步促进装备制造业高质量发展以及装备制造业高质量走向全球创造奠定更坚实的基础。

开创高效绿色低碳的企业服务新模式——基于云平台的焊接质量服务系统

基于20余年国际焊接质量管理体系在国内的推广实践,综合认证机构要求,以客户为中心,形成了包括企业认证所需要的前期培训、咨询、审核等服务的焊接专业服务体系,经多年的应用与发展,以云平台技术为基础,进行研究探索。实践表明,基于云平台的焊接质量专业服务系统能够很好地实现系统所需功能,并能够让服务更便捷、更高效、更低碳绿色,同时可以大大降低服务人员由于长途差旅劳累而影响服务质量的因素,以及认证机构可随时监督服务过程而使得服务更加公开透明且质量可控,为焊接质量专业服务系统更好地服务装备制造业高质量发展奠定更坚实的基础!

有限元模拟仿真在压力容器对接接管焊缝相控阵超声检测工艺设计中的研究与验证

针对大壁厚压力容器接管焊缝多为窄间隙对接焊接头,超声检测中存在扫查路径复杂、定量定性精度差和检出率相对较低等难点,引入有限元模拟仿真技术。通过建立工件3D模型和不同类型的缺陷,模拟各缺陷在压力容器筒体外壁和接管内壁相控阵超声检测时的响应情况,优化相控阵超声探头、楔块设计和探头运动轨迹,最终实现检测工艺的理论设计。在带有自然缺陷的模拟试块上,验证检测工艺的准确性和可靠性。对比有限元模拟仿真和在模拟试块上的实际检测情况表明,经过仿真设计过的相控阵超声检测工艺可有效提高接管窄间隙焊缝中缺陷的检出率和检测精度。

近十年NSF资助率和资助强度上升对我国科学基金资助工作的启示

美国国家科学基金会(National Science Foundation,U.S.,NSF)2022财年预算为88.4亿美元,比2021财年拨款增长4.1%,创历史新高。NSF官网数据显示,资助率从2013年的22%稳步提高到2022年的28%,平均资助强度也从52.5万美元/项增至80.6万美元/项。统计数据显示,NSF资助率稳步上升可归因于每年申请量从近50000项逐渐下降至40000项左右,而资助项目量维持在11000项左右;平均资助强度的提高得益于NSF在维持资助项目量不变的同时,年度预算大幅提高,从约60亿美元增加至接近90亿美元。本文基于近十年NSF总体资助变化,提出对我国科学基金资助工作启示,认为我国应该持续加大基础研究投入以提高自然科学基金资助率,将科研人才红利转化为高质量发展的动力,在大国科技竞争中占据有利地位。

Multistate transition and coupled solid-liquid modeling of motion process of long-runout landslide

The recognition,repetition and prediction of the post-failure motion process of long-runout landslides are key scientific problems in the prevention and mitigation of geological disasters.In this study,a new numerical method involving LPF3D based on a multialgorithm and multiconstitutive model was proposed to simulate long-runout landslides with high precision and efficiency.The following results were obtained:(a)The motion process of landslides showed a steric effect with mobility,including gradual disintegration and spreading.The sliding mass can be divided into three states(dense,dilute and ultradilute)in the motion process,which can be solved by three dynamic regimes(friction,collision,and inertial);(b)Coupling simulation between the solid grain and liquid phases was achieved,focusing on drag force influences;(c)Different algorithms and constitutive models were employed in phase-state simulations.The volume fraction is an important indicator to distinguish different state types and solid‒liquid ratios.The flume experimental results were favorably validated against long-runout landslide case data;and(d)In this method,matched dynamic numerical modeling was developed to better capture the realistic motion process of long-runout landslides,and the advantages of continuum media and discrete media were combined to improve the computational accuracy and efficiency.This new method can reflect the realistic physical and mechanical processes in long-runout landslide motion and provide a suitable method for risk assessment and pre-failure prediction.

Valorization of Camellia oleifera oil processing byproducts to value-added chemicals and biobased materials: A critical review

The C.oleifera oil processing industry generates large amounts of solid wastes,including C.oleifera shell(COS)and C.oleifera cake(COC).Distinct from generally acknowledged lignocellulosic biomass(corn stover,bamboo,birch,etc.),Camellia wastes contain diverse bioactive substances in addition to the abundant lignocellulosic components,and thus,the biorefinery utilization of C.oleifera processing byproducts involves complicated processing technologies.This reviewfirst summarizes various technologies for extracting and converting the main components in C.oleifera oil processing byproducts into value-added chemicals and biobased materials,as well as their potential applications.Microwave,ultrasound,and Soxhlet extractions are compared for the extraction of functional bioactive components(tannin,flavonoid,saponin,etc.),while solvothermal conversion and pyrolysis are discussed for the conversion of lignocellulosic components into value-added chemicals.The application areas of these chemicals according to their properties are introduced in detail,including utilizing antioxidant and anti-in-flammatory properties of the bioactive substances for the specific application,as well as drop-in chemicals for the substitution of unrenewable fossil fuel-derived products.In addition to chemical production,biochar fabricated from COS and its applications in thefields of adsorption,supercapacitor,soil remediation and wood composites are comprehensively reviewed and discussed.Finally,based on the compositions and structural characteristics of C.oleifera byproducts,the development of full-component valorization strategies and the expansion of the appli-cationfields are proposed.

国家自然科学基金视角下地理科学学科“双一流”建设成效及优化策略

“双一流”建设工程是我国在高等教育领域开展的重大国家战略,其开展与实施对学科人才队伍建设起到了极大的促进作用,并为抢占学科前沿高地与提高国际话语权提供了强有力的支撑。地理科学是理学门类的重要基础学科,其核心研究内容是人—地关系及其相互作用机理,并在“生态文明建设”“一带一路倡议”“乡村振兴”“全球变化与可持续发展”等国家重大需求中发挥着至关重要的学科作用。国家自然科学基金委员会是地理科学基础研究的主要资助机构,从国家自然科学基金委员会的管理角度审视当前“双一流”建设高校地理科学学科的建设情况,可为学科建设的优化布局提供支撑。

对非农业援助能否“以农兴工”——基于援非农技示范中心的准自然实验

农业现代化的推进是工业发展的基石与动力源泉。本文基于2000—2019年非洲54个国家的面板数据,以援非农技示范中心开始运营作为外生冲击事件,采用多时点双重差分法就对非农业援助带给受援国工业发展水平的影响予以考察,并对其作用路径进行探析。研究发现,对非农业援助的实施显著提升了受援国工业发展水平,作用路径为产品贡献(粮食和原材料供给)、市场贡献(生活消费和生产消费扩容)和要素贡献(劳动力转移和资本积累)。对非农业援助对经济发展水平低、政治和投资风险程度低、农业自然条件良好的受援国工业发展水平提升作用更强。拓展性分析表明,对非农业援助对受援国产生了“污染光环”效应。本文在丰富对非援助相关研究的同时,也为非洲各国通过重视农业进步进而推动“以农兴工”,最终实现工农联动发展,初步提供了依据。

实践导向主题(POT)如何调和语言教师信念、实践和身份的统一性?一项叙事研究

根据维果茨基的观点,praxis代表着理论与实践的统一。这一社会文化理论的概念为语言教师教育提供了重要的研究启示,但目前只有少数学者探讨了其含义(Johnson et al., 2020, 2022)。为了填补这一空白,我们旨在探索实践导向主题(praxis-oriented themes)如何影响TESOL和语言学项目中的导师-学员二人组的专业信念与实践的发展。此外,我们还研究了师生信念和实践的发展如何反过来影响师生关系,并进一步促进师生二人组的身份发展。本文选取叙事研究法,收集两对师生的相关语言学习和教学经历以及伴随这些经历产生的情感变化的叙事片段。研究发现:师生关系的变化主要分为三个阶段:提升知识、传承导师、建立自我。在这三个不同阶段,受访者的身份认同从学生变为新手科研者,再转变为中国文化的传承学者。本研究阐明praxis理论框架可以促进教师培训项目的发展,为语言教师和教师教育者提供了一定的见解。

Effect of infarct location and volume on cognitive dysfunction in elderly patients with acute insular cerebral infarction

BACKGROUND The aging of the population has become increasingly obvious in recent years,and the incidence of cerebral infarction has shown an increasing trend annually,with high death and disability rates.AIM To analyze the effects of infarct location and volume on cognitive dysfunction in elderly patients with acute insular cerebral infarction.METHODS Between January 2020 and December 2023,we treated 98 cases of elderly acute insula,patients with cerebral infarction in the cerebral infarction acute phase(3-4 weeks)and for the course of 6 months in Montreal Cognitive Assessment Scale(MoCA)for screening of cognition.Notably,58 and 40 patients were placed in the cognitive impairment group and without-cognitive impairment group,respec-tively.In patients with cerebral infarction,magnetic resonance imaging was used to screen and clearly analyze the MoCA scores of two groups of patients with different infarctions,the relationship between the parts of the infarction volume,and analysis of acute insula cognitive disorder in elderly patients with cerebral RESULTS The number of patients with cognitive impairment in the basal ganglia and thalamus was significantly higher than that without cognitive impairment(P<0.05).The total infarct volume in the cognitive impairment group was higher than that in the non-cognitive impairment group,and the difference was statistically significant(P<0.05).The infarct volumes at different sites in the cognitive impairment group was higher than in the non-cognitive impairment group(P<0.05).In the cognitive impairment group,the infarct volumes in the basal ganglia,thalamus,and mixed lesions were negatively correlated with the total MoCA score,with correlation coefficients of-0.67,-0.73,and-0.77,respectively.CONCLUSION In elderly patients with acute insular infarction,infarction in the basal ganglia,thalamus,and mixed lesions were more likely to lead to cognitive dysfunction than in other areas,and patients with large infarct volumes were more likely to develop cognitive dysfunction.The infarct volume in the basal ganglia,thalamus,and mixed lesions was significantly negatively correlated with the MoCA score.

非富勒烯受体有机太阳能电池稳定性研究进展

近年来,基于非富勒烯受体(NFAs)的有机太阳能电池(OSCs)取得了迅猛的发展。单异质结OSCs的光电转换效率(PCE)已突破19%,这进一步推动了有机光伏技术的商业化进程。光电转换效率的快速提升源于活性层材料的创新开发、器件工程的优化以及对器件物理的更深刻理解。然而,稳定性问题已成为制约其商业化的一个主要因素。目前,关于活性层材料和电池器件稳定性的研究仍相对有限。在本综述中,我们对NFA-OSCs不稳定性的机理进行了简要介绍,包括NFAs的光氧化降解、不稳定的共混薄膜形貌以及界面层诱导的NFAs不稳定性。同时,我们总结了近年来国内外关于提高NFA-OSCs稳定性的研究策略。期望本综述能为实现高效、稳定的NFA-OSCs提供有益的指导。

Uncovering the electrooxidation behavior of 5-hydroxymethylfurfural on Ni/Co electrodes

Biomass,derived from plant photosynthesis that captures carbon dioxide to form carbohydrates,offers vast renewable reserves.The electrooxidation of biomass,coupled with the hydrogen evolution reaction,enables the simultaneous production of biomass-based plastic monomers and green hydrogen,attracting significant scholarly interest.However,ambiguity remains regarding the adsorption mechanism at the catalyst surface(Langmuir-Hinshelwood or Eley-Rideal)and the adsorbed substrate groups.To address this,we prepared a Ni/Co electrode for the electrooxidation of 5-hydroxymethylfurfural(HMF)into 2,5-furandicarboxylic acid(FDCA)through a corrosion reaction and electro-reduction pathway.HMF conversion reached 100.00%,FDCA yield reached 96.82%,and Faradic efficiency(FE)reached 92.14%.Meaningfully,utilizing in-situ spectroscopy and electrochemical methods,this work provided valuable insights into active sites and catalyst surface adsorption.

Unveiling the chemistry behind the electrolytic production of hydrogen peroxide by oxygenated carbon

Oxygenated carbon materials exhibit outstanding electrocatalytic performance in the production of hydrogen peroxide(H2O2)through a two-electron oxygen reduction reaction.The nature of the active functional group and underlying reaction mechanism,however,remain unclear.Here,a comprehensive workflow was established to identify the active sites from the numerous possible structures.The common hydroxyl group at the notched edge demonstrates a key role in the two-electron process.The local chemical environment weakens the binding of OOH intermediate to substrate while enhancing interaction with solution,thereby promoting the H_(2)O_(2)production.With increasing pH,the intramolecular hydrogen bond between OOH intermediate and hydroxyl decreases,facilitating OOH desorption.Furthermore,the rise in selectivity with increasing potential stems from the suppression of the four-electron process.The active site was further validated through experiments.Guided by theoretical understanding,optimal performance was achieved with high selectivity(>95%)and current density(2.06 mA/cm^(2))in experiment.

Love wave propagation in one-dimensional piezoelectric quasicrystal multilayered nanoplates with surface effects

The exact solutions for the propagation of Love waves in one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)nanoplates with surface effects are derived.An electro-elastic model is developed to investigate the anti-plane strain problem of Love wave propagation.By introducing three shape functions,the wave equations and electric balance equations are decoupled into three uncorrelated problems.Satisfying the boundary conditions of the top surface on the covering layer,the interlayer interface,and the matrix,a dispersive equation with the influence of multi-physical field coupling is provided.A surface PQC model is developed to investigate the surface effects on the propagation behaviors of Love waves in quasicrystal(QC)multilayered structures with nanoscale thicknesses.A novel dispersion relation for the PQC structure is derived in an explicit closed form according to the non-classical mechanical and electric boundary conditions.Numerical examples are given to reveal the effects of the boundary conditions,stacking sequence,characteristic scale,and phason fluctuation characteristics on the dispersion curves of Love waves propagating in PQC nanoplates with surface effects.

Efficient and selective removal of Pb(Ⅱ) from landfill leachate using L-serine-modified polyethylene/polypropylene nonwoven fabric synthesized via radiation grafting technique

In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.

The interface structure and property of magnesium matrix composites:A review

Magnesium matrix composites have garnered significant attention in recent years owing to their exceptional lightweight properties and notable potential in various engineering applications.The interface generally acts as a“bridge”between the matrix and reinforcement,playing crucial roles in critical processes such as load transfer,failure behavior,and carrier transport.A deep understanding of the interfacial structures,properties,and effects holds paramount significance in the study of composites.This paper presents a comprehensive review of prior researches related to the interface of Mg matrix composites.Firstly,the different interfacial structures and interaction mechanisms encompassing mechanical,physical,and chemical bonding are introduced.Subsequently,the interfacial mechanical properties and their influence on the overall properties are discussed.Finally,the paper addresses diverse interface modification methods including matrix alloying and reinforcement surface treatment.

HepG2.2.15-derived exosomes facilitate the activation and fibrosis of hepatic stellate cells

BACKGROUND The role of exosomes derived from HepG2.2.15 cells,which express hepatitis B virus(HBV)-related proteins,in triggering the activation of LX2 liver stellate cells and promoting liver fibrosis and cell proliferation remains elusive.The focus was on comprehending the relationship and influence of differentially expressed microRNAs(DE-miRNAs)within these exosomes.AIM To elucidate the effect of exosomes derived from HepG2.2.15 cells on the activation of hepatic stellate cell(HSC)LX2 and the progression of liver fibrosis.METHODS Exosomes from HepG2.2.15 cells,which express HBV-related proteins,were isolated from parental HepG2 and WRL68 cells.Western blotting was used to confirm the presence of the exosomal marker protein CD9.The activation of HSCs was assessed using oil red staining,whereas DiI staining facilitated the observation of exosomal uptake by LX2 cells.Additionally,we evaluated LX2 cell proliferation and fibrosis marker expression using 5-ethynyl-2′-deoxyuracil staining and western blotting,respectively.DE-miRNAs were analyzed using DESeq2.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways were used to annotate the target genes of DE-miRNAs.RESULTS Exosomes from HepG2.2.15 cells were found to induced activation and enhanced proliferation and fibrosis in LX2 cells.A total of 27 miRNAs were differentially expressed in exosomes from HepG2.2.15 cells.GO analysis indicated that these DE-miRNA target genes were associated with cell differentiation,intracellular signal transduction,negative regulation of apoptosis,extracellular exosomes,and RNA binding.KEGG pathway analysis highlighted ubiquitin-mediated proteolysis,the MAPK signaling pathway,viral carcinogenesis,and the toll-like receptor signaling pathway,among others,as enriched in these targets.CONCLUSION These findings suggest that exosomes from HepG2.2.15 cells play a substantial role in the activation,proliferation,and fibrosis of LX2 cells and that DE-miRNAs within these exosomes contribute to the underlying mechanisms.

Construction and validation of a risk-prediction model for anastomotic leakage after radical gastrectomy: A cohort study in China

Objectives:Anastomotic leakage(AL)stands out as a prevalent and severe complication following gastric cancer surgery.It frequently precipitates additional serious complications,significantly influencing the overall survival time of patients.This study aims to enhance the risk-assessment strategy for AL following gastrectomy for gastric cancer.Methods:This study included a derivation cohort and validation cohort.The derivation cohort included patients who underwent radical gastrectomy at Sir Run Run Shaw Hospital,Zhejiang University School of Medicine,from January 1,2015 to December 31,2020.An evidence-based predictor questionnaire was crafted through extensive literature review and panel discussions.Based on the questionnaire,inpatient data were collected to form a model-derivation cohort.This cohort underwent both univariate and multivariate analyses to identify factors associated with AL events,and a logistic regression model with stepwise regression was developed.A 5-fold cross-validation ensured model reliability.The validation cohort included patients from August 1,2021 to December 31,2021 at the same hospital.Using the same imputation method,we organized the validation-queue data.We then employed the risk-prediction model constructed in the earlier phase of the study to predict the risk of AL in the subjects included in the validation queue.We compared the predictions with the actual occurrence,and evaluated the external validation performance of the model using model-evaluation indicators such as the area under the receiver operating characteristic curve(AUROC),Brier score,and calibration curve.Results:The derivation cohort included 1377 patients,and the validation cohort included 131 patients.The independent predictors of AL after radical gastrectomy included age65 y,preoperative albumin<35 g/L,resection extent,operative time240 min,and intraoperative blood loss90 mL.The predictive model exhibited a solid AUROC of 0.750(95%CI:0.694e0.806;p<0.001)with a Brier score of 0.049.The 5-fold cross-validation confirmed these findings with a calibrated C-index of 0.749 and an average Brier score of 0.052.External validation showed an AUROC of 0.723(95%CI:0.564e0.882;p?0.006)and a Brier score of 0.055,confirming reliability in different clinical settings.Conclusions:We successfully developed a risk-prediction model for AL following radical gastrectomy.This tool will aid healthcare professionals in anticipating AL,potentially reducing unnecessary interventions.

Mechanism of acupoint penetration acupuncture therapy regulating chondrocyte autophagy via the PI3K/Akt-mTOR pathway in KOA rats

Objective:To investigate whether acupoint penetration acupuncture(APA)could regulate chondrocyte autophagy and apoptosis via the PI3K/Akt-mTOR signaling pathway to reduce cartilage degeneration in knee osteoarthritis(KOA)rats.Methods: KOA was induced in rats via intra-articular injection of sodium iodoacetate resolution.Forty male Sprague-Dawley rats were randomly assigned to blank control,model,APA,electro-acupuncture(EA),and sham model groups(n=8)and those in the APA and EA groups received their respective therapies.Following completion of the treatment course,histological examinations of cartilage and muscle were conducted.Levels of apoptosis-and autophagy-related factors,including Bax,Bcl-2,mTOR,ULK-1,and Beclin-1 protein,and mRNAs were assessed.Additionally,β-endorphin(β-EP)concentrations in the brain and serum were measured.Results: Histological analysis revealed that APA alleviated cartilage and muscle damage compared with the model group.APA inhibited cartilage degeneration by modulating the expression of apoptosis-and autophagy-related proteins and mRNA,thus preventing chondrocyte apoptosis.In the APA group,Bax and mTOR protein levels were significantly lower than those in the model group(both P=.024).Conversely,the Bcl-2 expression level was significantly higher than that in the EA group(P=.035).Additionally,ULK-1 expression was significantly lower than that in the EA group(P=.045).The mRNA level of Bax was significantly higher than that in the blank control group(P<.001).However,Beclin-1 levels were significantly higher than those in both the model and EA groups(both P<.001).ELISA results showed a significant decrease in the concentration ofβ-EP in the brains of the rats in the APA group compared with those in the model group(P=.032).Conclusions: APA reduced osteoarthritis-related pain and alleviated cartilage damage by upregulating chondrocyte autophagy and down-regulating apoptosis via signaling pathways involving PI3K/Akt-mTOR in KOA rats.