Research on Euclidean Algorithm and Reection on Its Teaching

In this paper,we prove that Euclid's algorithm,Bezout's equation and Divi-sion algorithm are equivalent to each other.Our result shows that Euclid has preliminarily established the theory of divisibility and the greatest common divisor.We further provided several suggestions for teaching.

Chiral inorganic nanocatalysts for electrochemical and enzyme⁃mimicked biosensing

In recent years,chiral inorganic nanomaterials have become promising candidates for applications in sensing,catalysis,biomedicine,and photonics.Plasmonic nanomaterials with an intrinsic chiral structure exhibit intriguing geometry‑dependent optical chirality,which benefits the combination of plasmonic characteristics with chirality.Recent advances in the biomolecule‑directed geometric control of intrinsically chiral plasmonic nanomaterials have further provided great opportunities for their widespread applications in many emerging technological areas.In this review,we present the recent progress in biosensing using chiral inorganic nanomaterials,with a particular focus on electrochemical and enzyme‑mimicking catalytic approaches.This paper commences with a review of the basic tenets underlying chiral nanocatalysts,incorporating the chiral ligand‑induced mechanism and the architectures of intrinsically chiral nanostructures.Additionally,it methodically expounds upon the applications of chiral nanocatalysts in the realms of electrochemical biosensing and enzyme‑mimicking catalytic biosensing respectively.Conclusively,it proffers a prospective view of the hurdles and prospects that accompany the deployment of chiral nanoprobes for nascent biosensing applications.By rational design of the chiral nanoprobes,it is envisioned that biosensing with increasing sensitivity and resolution toward the single‑molecule level can be achieved,which will substantially promote sensing applications in many emerging interdisciplinary areas.

The Dantzig Selector:Sparse Signals Recovery via l_(1-q)Minimization Model

We propose the Dantzig selector based on the l_(1-q)(1<q≤2)minimization model for the sparse signal recovery.First,we discuss some properties of l_(1-q)minimization model and give some useful inequalities.Then,we give a sufficient condition based on the restricted isometry property for the stable recovery of signals.The l_(1-2)minimization model of Yin-Lou-He is extended to the l_(1-q)minimization model.

深层页岩储层裂缝识别及有效性评价方法研究及应用——以四川盆地南部为例

四川盆地南部地区(以下简称川南)深层页岩储层断裂发育,直接影响页岩气水平井的工程施工和有效建产。基于川南五峰组—龙马溪组页岩岩心,开展岩石物理实验和数值模拟实验,得到了不同尺度、不同产状、不同充填物质的裂缝声学响应特征,分析了裂缝对声波衰减能力的影响因素,建立了1套页岩气水平井裂缝识别和有效性评价方法。结果表明:纵波、横波和斯通利波的振幅衰减受裂缝倾角和裂缝宽度的共同影响,其衰减能力随裂缝宽度增加呈指数增加,随裂缝倾角的增加而降低。斯通利波对充填流体裂缝敏感,可识别和评价含气、含水的有效裂缝;纵波和偶极横波对充填方解石裂缝敏感,可识别和评价充填方解石的无效裂缝。基于反射波成像识别的裂缝结果与成像测井、岩心识别裂缝类型一致,验证了有效性评价方法的可靠性。将研究成果应用于页岩气水平井实测资料,精细评价了页岩气水平井断裂风险位置,有效保障了“一段一策”压裂分段的优化设计。

高黏附水凝胶的制备及其在传感领域的应用

针对传统水凝胶作为柔性应变传感器应用时过分依赖黏合剂而导致信号检测不精确等问题,制备了一种高黏附性的聚丙烯酸/2-丙烯酸胺-2-甲基丙磺酸/甲基丙烯酸羟乙酯(p(AA-AMPS-HEMA))水凝胶,并应用于柔性应变传感器。研究结果表明,该水凝胶不仅展现了卓越的力学性能(拉伸应力为195.02 kPa,拉伸应变为1193.55%)和出色的黏附力(对猪皮黏附强度可达38.94 kPa),还具备稳定灵敏的传感特性。进一步将其组装应用于柔性应变传感器,该传感器能够准确捕捉并监测到手指弯曲、手腕活动以及膝盖弯曲等人体多项运动。该水凝胶在智能传感领域展现出较好的应用前景。

不同应变率加载下硅的高压相变行为

高压相变是凝聚态物理、地球与行星科学、材料科学等领域关注的核心问题之一,而加载应变率是相变动力学过程的重要影响因素。由于动态加载下物质相结构原位诊断技术的不足以及宽广加载应变率下物质高压相变系统实验研究的缺失,难以开展基于原子尺度物理机制的相变动力学过程建模和数值模拟研究。由于硅的高压相极其丰富,且拥有大量亚稳相,动力学因素在其高压相变过程中发挥着至关重要的作用,因此,硅是研究高压相变动力学的理想材料,对普适相变动力学过程的理论建模具有重要意义。以硅为例,介绍其在准静态、中等应变率和高应变率加载下的相变行为,探讨加载应变率对其高压相变行为的影响。

基于NOMA的共生反向散射通信的性能分析

非正交多址接入和环境反向散射通信是提高无线通信系统频谱效率的关键技术.针对能量受限问题,提出了一种基于瑞利衰落信道的下行非正交多址接入多路传输的共生反向散射通信系统.该系统由1个源节点S、1个反向散射设备BD和1个目的节点D组成.考虑到实际的非线性能量收集模型,在满足反射设备的能量因果约束的情况下,采用了一种最优动态反射系数以最大化反向散射信号的功率,推导了该系统中断概率的解析表达式,通过仿真验证了理论推导的正确性.仿真结果表明,反射设备电路的自身损耗对系统中断性能有重要影响.此外,通过仿真对比分析了基于非正交多址的共生反向散射通信系统和基于正交多址的共生反向散射通信系统性能,结果表明基于非正交多址的共生反向散射通信系统具有更好的中断性能.

基于改进YOLOv8的轻量化小麦病害检测方法

为提高小麦病害检测精度,实现将模型方便快速部署到移动端,该研究提出了一种基于改进YOLOv8的轻量化小麦病害检测方法。首先,使用PP-LCNet模型替换YOLOv8网络结构的骨干网络,并在骨干网络层引入深度可分离卷积(depthwise separable convolution, DepthSepConv)结构,减少模型参数量,提升模型检测性能;其次,在颈部网络部分添加全局注意力机制(global attention mechanism, GAM)模块,强化特征中语义信息和位置信息,提高模型特征融合能力;然后,引入轻量级通用上采样内容感知重组(content-aware reassembly of features,CARAFE)模块,提高模型对重要特征的提取能力;最后,使用Wise-IoU(weighted interpolation of sequential evidence for intersection over union)边界损失函数代替原损失函数,提升网络边界框回归性能和对小目标病害的检测效果。试验结果表明,对于大田环境下所采集的小麦病害数据集,改进后模型的参数量及模型大小相比原YOLOv8n基线模型分别降低了12.5%和11.3%,同时精确度(precision)及平均精度均值(mean average precision,m AP)相较于原模型分别提高了4.5和1.9个百分点,优于其他对比目标检测算法,可为小麦病害检测无人机等移动端检测装备的部署和应用提供参考。

内观认知疗法对医学生焦虑水平、自我效能感和应对方式的干预及机制

目的:探究内观认知疗法对医学生焦虑水平、自我效能感和应对方式的影响,并考察医学生内观认知疗法干预、自我效能感、应对方式和焦虑水平间的关系,以期为医学生心理健康教育工作和NCT疗法的作用机制研究提供理论支持。方法:采用随机数字表法将70名符合筛选标准的研究对象随机分配到内观认知疗法组和心理健康教育组,每组35人。内观认知疗法组接受为期7天的内观认知疗法干预,心理健康教育组接受相同时间的常规心理健康教育,最终共68人完成试验(内观认知疗法组34人,心理健康教育组34人)。干预前后使用SAS、GSES、SCSQ量表对两组研究对象进行测评。结果:①干预前,内观认知疗法组与心理健康教育组在焦虑,自我效能感,积极和消极应对方式得分上均不存在显著差异。②干预后,内观认知疗法组焦虑得分显著降低(t=5.835;P<0.01),自我效能感和积极应对方式得分均显著升高(t=2.289,4.668;P<0.05),消极应对方式得分不存在显著差异,干预前后心理健康教育组在上述所有量表得分中均不存在显著差异。③干预后,内观认知疗法组自我效能感和积极应对方式得分显著高于心理健康教育组(t=2.653,3.122;P<0.01),焦虑得分显著低于心理健康组(t=2.562;P<0.05)。④中介效应检验方面,内观认知疗法既可以直接影响医学生焦虑水平(β=-0.293,95%CI=-3.755~0.008),也可以通过自我效能感的中介作用(β=-0.307,95%CI=-0.612~-0.028)、积极应对方式的中介作用(β=0.140,95%CI=-0.293~-0.004)及自我效能感和积极应对方式的链式中介作用(β=0.222,95%CI=-0.553~-0.022)间接影响医学生焦虑水平。结论:内观认知疗法是一种能够有效降低医学生焦虑水平的干预手段,既能直接缓解焦虑,也能通过提高医学生自我效能感水平,改善积极应对方式间接降低医学生焦虑水平。

顿号分隔的并列成分与煞尾的“等/等等”之间能否用逗号?

《标点符号用法》(GB/T 15834—2011)附录B规定,顿号分隔的并列成分与“等/等等”之间不能使用点号,并举出相应的示例。但是在实际语料中,如果“等/等等”出现在句末,则此类用法甚多。从实际停顿、使用习惯和接受程度、辅助消歧三个方面,通过分析语料、问卷调查、变换分析的方法,说明该用法的合理性。同时,也阐明其辅助消歧作用的局限性。通过这一个案研究,一方面,可以为正在修订的《标点符号用法》提供具体方案;另一方面,也建议图书质检人员和国际中文教师等对现行规范中的相关内容从宽执行。

Role of inclination angle on columnar-to-equiaxed transition in the eutectic Al-5Mg-2Si alloy fabricated by laser powder bed fusion

In this study,the effect of inclination angles relative to the building direction in the additively manufactured eutectic Al-5Mg-2Si alloy was investigated through the laser powder bed fusion(LPBF).The microstructures and mechanical properties of the Al-5Mg-2Si alloy manufactured with different inclination angles(0°,30°,45°,60°and 90°)were reported and discussed.It is found that the“semicircular”melt pool(MP)in the load bearing face of 0°sample was eventually transformed into“stripe-like”MP in the 90°sample,accompanied by an increased fraction of melt pool boundaries(MPBs).Moreover,the microstructural analysis revealed that the columnar-to-equiaxed transition(CET)of theα-Al grains and eutectic Mg2Si was completed in the 90°sample,which were significantly refined with the average size of 10.6μm and 0.44μm,respectively.It is also found that the 90°sample exhibited good combination of strength and elongation(i.e.yield strength of 393 MPa,ultimate tensile strength of 483 MPa and elongation of 8.1%).The anisotropic mechanical properties were highly associated with the refined microstructures,thermal stress,and density of MPBs.Additionally,the CET driven by inclination angles was attributed to the variation of thermal conditions inside the local MPs.

Ultrahigh strength and improved electrical conductivity in an aging strengthened copper alloy processed by combination of equal channel angular pressing and thermomechanical treatment

In this paper,equal channel angular pressing and thermomechanical treatment was employed to improve the strength and electrical conductivity of an aging strengthened Cu-Ti-Cr-Mg alloy,and the microstructure and properties of the alloy were investigated in detail.The results showed that the samples deformed by the combination of cryogenic equal channel angular pressing(ECAP)and rolling had good comprehensive properties after aging at 400℃.The tensile strength of the peak-aged and over-aged samples was 1120 MPa and 940 MPa,with their corresponding electrical conductivity of 14.7%IACS and 22.1%IACS,respectively.ECAP and cryogenic rolling introduced high density dislocations,leading to the inhibition of the softening effects and refinement of the grains.After a long time aging at 400℃,the alloy exhibited ultra-high strength with obvious increasing electrical conductivity.The high strength was attributed to the synergistic effect of work hardening,grain refinement strengthening and precipitation strengthening.The precipitation of a large amount of Ti atoms from the matrix led to the high electrical conductivity of the over-aged sample.

Oxidation behavior of ferrovanadium spinel particles in air:Isothermal kinetic and reaction mechanism

The oxidation behavior of ferrovanadium spinel(FeV_(2)O_(4)),synthesized via high-temperature solid-state reaction,was investigated using thermogravimetry,X-ray diffractometry,and X-ray photoelectron spectroscopy over the temperature range of 450–700℃.The results revealed that the oxidation process of FeV_(2)O_(4)can be divided into three stages with the second stage being responsible for maximum weight gain due to oxidation.Three classical methods were employed to analyze the reaction mechanisms and model functions for distinct oxidation stages.The random nucleation and subsequent growth(A_(3))kinetic model was found to be applicable to both initial and secondary stage.The third stage of oxidation was consistent with the three-dimensional diffusion,spherical symmetry(D_(3))kinetic mode.Both the model-function method and the model-free method were utilized to investigate the apparent activation energy of the oxidation reaction at each stage.It was found that the intermediates including Fe_(3)O_(4),VO_(2),V_(2)O_(3),and Fe_(2.5)V_(7.11)O_(16),played significant roles in the oxidation process prior to the final formation of FeVO_(4)and V_(2)O_(5)through oxidation of FeV_(2)O_(4).

Plasmon Induced Heat Funneling from Au to Cu in the Bimetallic Au@Cu Core-Shell Nanoparticles

The bimetallic nanostructures that mix a plasmonic metal with a transition metal in the form of the core-shell nanoparticles are promising to promote catalytic performance.But it is still unclear how the heat(hot electrons and phonons)transfers on the interface between two metals.We have designed and synthesized Au@Cu bimetallic nanoparticles with Au as core and Cu as shell.By using transient absorption spectroscopy,we find that there are two plasmon induced heat funneling processes from Au core to Cu shell.One is the electron temperature equilibrium(electron heat transfer)with equilibration time of~560 fs.The other is the lattice temperature equilibrium(lattice heat transfer)with equilibration time of~13 ps.This plasmon induced heat funneling may be universal in similar bimetallic nanostructures,so our finding could contribute to further understanding the catalytic mechanism of bimetallic plasmonic photothermal catalysis.

MATRICES OVER A REDUCED RING AS SUMS OF THREE TRIPOTENTS

In this paper,we study reduced rings in which every element is a sum of three tripotents that commute,and determine the integral domains over which every n£n matrix is a sum of three tripotents.It is proved that for an integral domain R,every matrix in M_(n)(R)is a sum of three tripotents if and only if R■Zp with p=2,3,5 or 7.

On the systematic position of Cacosyndya Kirby(Hymenoptera:Tenthredinidae)with redescription of Cacosyndya dimorpha Freymuth

A peculiar sawfly genus from middle Asia,Cacosyndya Kirby,1883 and the type species Cacosyndya dimorpha(Freymuth,1870)are redescribed and illustrated.The systematic position of this genus in Tenthredinidae is discussed.The females in the genus are apterous,the only known apterous Symphytan,but the male is normally winged.Cacosyndya is not a member of Fenusinae or Heterarthrinae,but a member of Phymatocerini of Blennocampinae,Tenthredinidae as shown by the structure of the antenna,wing venation and body structure.The relationship between Cacosyndya and members of Phymatocerini is briefly discussed.

A Multifunctional Chiral Metasurface with Asymmetric Transmission and Linear-Polarization Conversion

In this paper,a multifunctional chiral metasurface is presented to achieve asymmetric transmission(AT)and linear-polarization conversion(LPC).The designed metasurface consists of a cross swords-like shape and two holes in the lower side of the unit cell.In the frequency band from 8.3 GHz to 10.4 GHz,AT is realized with more than 90%efficiency and the same chiral metasurface transforms linear polarized wave into its orthogonal counterpart with high efficiency.For LPC,the polarization conversion ratio(PCR)is greater than 95%.The proposed metasurface is stable against the incident angles of striking electromagnetic(EM)waves up to 60°for both operations of AT and LPC.

Hot Isostatic Pressing and Characterizations of Eu^(3+)-doped(Gd,Lu)_(2)O_(3) Transparent

(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the co-precipitation method.Using the synthesized nano-powders as initial material,Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics were fabri-cated by vacuum pre-sintering at different temperatures for 2 h and hot isostatic pressing(HIP)at 1750℃for 3 h in ar-gon.The influence of pre-sintering temperature on the microstructure,optical and luminescence properties was investi-gated.The Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics pre-sintered at 1625℃for 2 h combined with HIP post-treatment show the high-est in-line transmittance of 75.2%at 611 nm.The photoluminescence(PL)and X-ray excited luminescence(XEL)spectra of the Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)transparent ceramics demonstrate a strong red emission peak at 611 nm due to the^(5)D_(0)→^(7)F_(2) transition of Eu^(3+).The PL,PLE and XEL intensities of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics show a trend of first ascending and then descending with the increase of pre-sintering temperature.The thermally stimulated lumines-cence(TSL)curve of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics presents one high peak at 178 K and two peaks with lower intensities at 253 K and 320 K.The peak at 320 K may be related to oxygen vacancies,and the lumines-cence peak at 178 K is related to defects caused by the valence state changes of Eu^(3+)ions.

Geriatric nursing competence of clinical nursing staff at different hospital levels in Chongqing,China:A cross-sectional study

Objectives:This study aimed to survey the geriatric nursing competencies of clinical nursing staff in Chongqing City,China,and provide suggestions to enhance these competencies.Methods:This study was conducted in 204 hospitals in Southwest China from December 24,2022 to January 7,2023.The“Geriatric Nursing Competence of Clinical Nurse Investigation Tool”was used to explore factors that influence geriatric nurses’competencies via stratified sampling.The survey was conducted by distributing and collecting questionnaires through the online platform Wenjuanxing.Results:A total of 10,692 nurses answered the questionnaires.Of these questionnaires,9,442 were valid.The total geriatric nursing competence score of the clinical nursing staff was 2.29±0.81,the secondary hospital score was 2.23±0.78,and the tertiary hospital’s overall mean score was 2.33±0.83.The factors that influenced secondary hospitals included the department of medicine,age of nurses and total length of career(P<0.05).The factors that influenced tertiary hospitals included the department of medicine,age of nurses,nurses’professional title,and geriatric practical advanced nurses’certification(P<0.05).Conclusions:Geriatric nursing competence among clinical nursing staff is imbalanced at a lower-middle level and is influenced by various factors.Thefindings highlight the need for further clinical training in geriatric nursing.The training of geriatric nurses should focus on necessary clinical skills and on preparing them to adequately manage comprehensive geriatric syndromes.

Microstructure evolution and hot workability of in-situ synthesized Ti_(2)AlC/TiAl composite

The in-situ micro-nano Ti_(2)AlC particles reinforced TiAl(Ti_(2)AlC/TiAl)composite was fabricated using spark plasma sintering.The hot workability of Ti_(2)AlC/TiAl composite was studied,and the effect of micro-nano particles on flow stress and dynamic recrystallization of composite was discussed.The results showed that the micro-nano Ti_(2)AlC particles included strengthening and softening effects during hot deformation,resulting in the fact that the Ti_(2)AlC/TiAl composite exhibited a higher flow stress and more sufficient dynamic recrystallization.The strengthening effect was mainly attributed to the Ti_(2)AlC particles induced refinement strengthening and hindered dislocation motion at the initial stage.Moreover,the precipitation of nano-TiCr2 particles induced by stress concentration during hot deformation also contributed to higher flow stress via impeding dislocation motion.Meanwhile,the refined microstructure and dislocation pile-up caused by micro-nano particles during deformation provided more nucleation sites for dynamic recrystallization,which significantly promoted the dynamic recrystallization of the second stage.The present results reveal that the Ti_(2)AlC/TiAl composite exhibited excellent hot workability,which is important to promote the application of TiAl alloys.