Influence of Carbon Content on Element Diffusion in Silicon Carbide-Based TRISO Composite Fuel

The coating layers of Tri-structural Isotropic Particles(TRISO)serve to protect the kernel and act as barriers to fission products.Sintering aids in the silicon carbide matrix variably react with TRISO coating layers,leading to the destruction of the coating layers.Investigating how carbon content affects element diffusion in silicon carbide-based TRISO composite fuel is of great significance for predicting reactor safety.In this study,silicon carbide-based TRISO composite fuels with different carbon contents were prepared by adding varying amounts of phenolic resin to the silicon carbide matrix.X-ray Diffraction(XRD)and Scanning Electron Microscopy(SEM)were employed to characterize the phase composition,morphology,and microstructure of the composite fuels.The elemental content in each coating layer of TRISO was quantified using Energy-Dispersive X-ray Spectroscopy(EDS).The results demonstrated that the addition of phenolic resin promoted the uniform distribution of sintering aids in the silicon carbide matrix.The atomic percentage(at.%)of aluminum(Al)in the pyrolytic carbon layer of the TRISO particles reached its lowest value of 0.55%when the phenolic resin addition was 1%.This is because the addition of phenolic resin caused the Al and silicon(Si)in the matrix to preferentially react with the carbon in the phenolic resin to form a metastable liquid phase,rather than preferentially consuming the pyrolytic carbon in the outer coating layer of the TRISO particles.The findings suggest that carbon addition through phenolic resin incorporation can effectively mitigate the deleterious reactions between the TRISO coating layers and sintering aids,thereby enhancing the durability and safety of silicon carbide-based TRISO composite fuels.

Challenges and Teaching Reform Strategies in Vocational College Engineering Training Courses

With the rapid development of vocational education,engineering training has become a crucial course for cultivating highly skilled technical professionals,highlighting its importance.However,vocational college engineering training courses still face numerous challenges during the actual teaching process,which affect the effectiveness of course teaching and the enhancement of students’engineering competence.This article thoroughly analyzes the main problems existing in current engineering training course teaching,focusing on four aspects:students’cognitive differences,inadequate course development,poor course adaptability,and limited teaching resources.Based on this analysis and previous research findings,targeted strategies are proposed,including enhancing students’course cognition,clarifying course positioning,improving course adaptability,and optimizing the allocation of teaching resources.Furthermore,this article preliminarily verifies the effectiveness of some reform strategies through a small-scale teaching experiment.This study aims to provide theoretical guidance and practical reference for enhancing the teaching quality of vocational college engineering training courses.

神经源性膀胱患者使用自我管理微信小程序体验的质性研究

目的了解神经源性膀胱患者使用自我管理微信小程序的感知好处,并识别阻碍其使用的关键因素。方法采用质性研究设计,通过目的抽样选取深圳市2所三级甲等医院康复科住院并试用自我管理微信小程序2周的19例神经源性膀胱患者进行半结构化访谈,运用内容分析法进行资料分析。结果患者认为该自我管理程序是有帮助的,同时存在使用的障碍因素。3个感知益处包括:方便、灵活、直观;促进患者自我管理;为照护者和家庭成员提供指导。阻碍患者使用该程序的障碍因素包括:患者消极的膀胱自我管理态度和患者特征;对移动医疗风险的担忧;小程序升级的必要性。结论神经源性膀胱患者使用微信小程序进行自我管理是可行的,可以满足患者在住院期间和出院后获取信息的需求。研究发现的自我管理程序使用促进和障碍因素,为医疗机构实施移动医疗干预措施促进神经源性膀胱患者的自我管理提供了有价值的信息。

分数阶广义KDV方程的精确解

本文将分数阶复变换方法和椭圆函数展开法相结合,给出了求解分数阶广义KDV方程的复变换椭圆函数展开法。进而得到了分数阶广义KDV方程的周期波解和孤立波解。

Midwives’views and experiences of providing midwifery care in the task shifting context:a meta-ethnography approach

Objective:This study aimed to explore the existing knowledge about midwives’views and experiences of providing care for women in the context of task shifting.Methods:We conducted a qualitative systematic review using meta-ethnography to describe the views and experiences of midwives on providing care in the context of task shifting.Comparative textual analysis of published qualitative studies involved translation of first-order key concepts and meanings from included studies to generate second-and third-order concepts.A grid was made to identify core findings and compare them reciprocally.Results:Thirty-six qualitative studies met the inclusion criteria.The literature comprised of 32 first key concepts.Eight second-order constructs emerged,and three third-order interpretations were generated.The three overarching themes were:(1)midwives perceived themselves as providing culturally competent and high quality women-centered care;(2)they valued their profession but saw it as complex and challenging;(3)as health professionals,they reported a variety of organizational,cultural,and professional barriers to providing women-centered care.Conclusions:While performing a specific task in the task shifting context,midwives perceived their crucial roles and responsibilities,along with achieved value and reward.However,due to a range of existing barriers,the caring task posed great challenges in completely implementing women-centered care.It is essential for systems to identify and eliminate these barriers early,to consider midwives’emotional well-being,and to develop overall strategies to better support the midwifery workforce.Policy makers and administrators should establish a supportive environment to facilitate midwives to perform women-centered caring tasks in more effective and efficient ways.

Determination of Inorganic Anions and Melamine in Fertilizers by Ion Chromatography

A chromatographic analysis method for determining inorganic anions and melamine in fertilizers was established using ion chromatography(IC).The fertilizer samples were extracted by ultrasonic method with 7 g/L trichloroacetic acid solution and centrifuged.The supernatant is purified by a solid phase extraction column.Then,the anions in the solution were purified using SH-AP-1(250 mm×4.0 mm)as a separation column,and measured by a suppressed conductivity detector;the melamine in the solution was separated using SH-CC-4(200 mm×4.0 mm)as a separation column and detected by a UV detector.The results show that the mass concentration of anions had a linear relationship with its peak area within a certain range,the linear correlation coefficient r of the standard curve was greater than 0.999,the recovery rate of spiked samples was 93.4%-104.4%,and the relative standard deviation(RSD)of the measured value(n=6)was less than 4%.Thus,this method is widely suitable for detection of anions and cations in a variety of fertilizer samples.

Catalytic effects of V-and O-species derived from PrF_(3)/V_(2)C for efficient hydrogen storage in MgH_(2)

Magnesium hydride(MgH_(2))is considered as an ideal hydrogen storage material with excellent hydrogen capacity,but the slow kinetics impedes its application.Herein,an efficient additive of V2C MXene-anchored PrF_(3) nanoparticles(PrF_(3)/V_(2)C)was synthesized,which presents excellent catalytic effect in improving the reversibility and stability of hydrogen storage in MgH_(2).The initial dehydrogenation temperature of the 5 wt.% PrF_(3)/V_(2)C-containing MgH_(2)(182℃) is 105℃ lower than that of pure MgH_(2),and 6.5 wt.%hydrogen is rapidly released from 5 wt.%PrF_(3)/V_(2)C-added MgH_(2)sample in 6 min at 240℃.In addition,5 wt.%PrF_(3)/V_(2)C-containing MgH_(2) sample possesses outstanding reversible hydrogen storage capability of 6.5 wt.% after 10 cycles of dehydrogenation and hydrogenation.Microstructure analysis shows that the introduction of Pr improves the stability of V-species(V^(0)and V^(2+))and O-species(lattice oxygen(OL)and vacancy oxygen(OV))formed during ball milling,promotes the interaction between V-species and O-species,and enhances their reversibility,which contributes to the significant improvement in re/dehydrogenation reversibility and cycling stability of MgH_(2).This study provides effective ideas and strategies for the purpose of designing and fabricating high-efficient catalysts for solid-state hydrogen storage materials.

Size-selective hybridization chain reaction for accurate signal amplification in living cancer cells

Accurate signal amplification in living cells is highly important in biomedical research and medical diagnostics.Benefiting from its enzyme-free,efficient isothermal signal amplification ability,hybridization chain reaction(HCR)plays an important role in intracellular signal amplification;however,HCR fails the accurate signal amplification in the situation when the properties of some biological targets and analogues are too similar.Particularly,their signal amplification accuracy for mature mi RNAs is unsatisfactory due to the signal interference of precursor micro RNAs(abbreviated as pre-mi RNAs),which also contain the sequence of mature mi RNAs.Herein,we develop the first example of size-selective hybridization chain reaction probe for accurate signal amplification,which achieved accurate and sensitive biosensing of mature mi RNAs in living cancer cells.Our probe,termed as q Tcage,consists of a DNA nanocage for size-selective responsive to mature mi RNAs,as well as a quadrivalent tetrahedral DNA structure for HCR signal amplification.Benefiting from the size-selectivity of DNA nanocage,shorter mature mi RNAs(19–23 nt)rather than longer pre-mi RNAs(60–70 nt)could enter the cavity to release triggers strand,which activates HCR reaction for fluorescence signal recovery.The probe efficiently reduces signal interference of pre-mi RNAs and improves the imaging sensitivity for intracellular mature mi RNAs,which was successfully applied for mature mi RNAs imaging during drug treatment.Overall,this strategy provides the hybridization chain reaction with the feature of size-selective ability,which holds promise for further accurate signal amplification in biological processes study and clinical diagnostics.

The Ap-2α/Elk-1 axis regulates Sirpα-dependent tumor phagocytosis by tumor-associated macrophages in colorectal cancer

The inhibitory receptor signal regulatory protein-α(Sirpα)is a myeloid-specific immune checkpoint that engages the“don’t eat me”signal CD47,which is expressed on tumor and normal tissue cells.However,the profile and regulatory mechanism of Sirpαexpression in tumor-associated macrophages(TAMs)are still not clear.Here,we found that the expression of Sirpαin TAMs increased dynamically with colorectal cancer(CRC)progression.Mechanistically,CRC cell-derived lactate induced the nuclear translocation of the transcription factor Ap-2αfrom the cytoplasm in TAMs.Ap-2αfunctioned as a transcription factor for Elk-1 by binding to the conserved element GCCTGC located at−1396/−1391 in the mouse Elk-1 promoter.Subsequently,the Elk-1 protein bound to two conserved sites,CTTCCTACA(located at−229/−221)and CTTCCTCTC(located at−190/−182),in the mouse Sirpαpromoter and promoted Sirpαexpression in TAMs.Functionally,the macrophage-specific knockout of Ap-2αnotably promoted the phagocytic activity of TAMs and suppressed CRC progression,whereas these effects were prevented by the transgenic macrophage-specific expression of Elk-1,which regulated TAM phagocytosis and CRC development in a Sirpα-dependent manner.Furthermore,we showed that Elk-1 expression was positively correlated with Sirpαexpression in TAMs and was associated with poor survival in CRC patients.Taken together,our findings revealed a novel mechanism through which CRC evades innate immune surveillance and provided potential targets for macrophage-based immunotherapy for CRC patients.

Reversible control of magnetic and transport properties of NdNiO_(3-δ)epitaxial films

Rare-earth nickelates possess intrinsic charge order,orbital order,and electron-lattice coupling,which make them very interesting for applications in oxide-based electronic devices.In this study,we grew NdNiO_(3-δ)(NNO) films with oxygen pressures changing from 27 to 10^(-5) Pa.With decreasing oxygen pressure,the antiferromagnetic state of the NNO film becomes a ferromagnetic state,and the resistance increases significantly.According to combined X-ray absorption spectro scopy and X-ray linear dichroism measurements,the ratio of Ni^(2+)-ions increases with decreasing oxygen-pressure,and the preferred orbital occupation changes from x^(2)-y^(2) to 3 z^(2)-r^(2).In addition,using the ionic-liquid gating method to control the migration of oxygen vacancies,both the magnetic properties and resistance of NNO films can be modulated reversibly.The oxygen vacancy induces a valence in the Ni ions and the orbital occupation changes,which alters the magnetic properties and the electronic transport in these NNO films.This study describes a novel tunable method for electronic devices that use NdNiO_(3-δ) films,and opens new doors for future improvements and functionalities.