Lift-Off Effect of Koch and Circular Differential Pickup Eddy Current Probes

A flexible or planar eddy current probe with a differential structure can suppress the lift-off noise during the inspection of defects.However,the extent of the lift-off effect on differential probes,including different coil structures,varies.In this study,two planar eddy current probes with differential pickup structures and the same size,Koch and circular probes,were used to compare lift-off effects.The eddy current distributions of the probes perturbed by 0°and 90°cracks were obtained by finite element analysis.The analysis results show that the 90°crack can impede the eddy current induced by the Koch probe even further at relatively low lift-off distance.The peak-to-peak values of the signal output from the two probes were compared at different lift-off distances using finite element analysis and experimental methods.In addition,the effects of different frequencies on the lift-off were studied experimentally.The results show that the signal peak-to-peak value of the Koch probe for the inspection of cracks in 90°orientation is larger than that of the circular probe when the lift-off distance is smaller than 1.2 mm.In addition,the influence of the lift-off distance on the peak-to-peak signal value of the two probes was studied via normalization.This indicates that the influence becomes more evident with an increase in excitation frequency.This research discloses the lift-off effect of differential planar eddy current probes with different coil shapes and proves the detection merit of the Koch probe for 90°cracks at low lift-off distances.

A High-Resolution Measurement Method for Inner and Outer 3D Surface Profiles of Laser Fusion Targets Using a Laser Differential Confocal–Atomic Force Probe Technique

The high-resolution and nondestructive co-reference measurement of the inner and outer threedimensional(3D)surface profiles of laser fusion targets is difficult to achieve.In this study,we propose a laser differential confocal(LDC)–atomic force probe(AFP)method to measure the inner and outer 3D surface profiles of laser fusion targets at a high resolution.This method utilizes the LDC method to detect the deflection of the AFP and exploits the high spatial resolution of the AFP to enhance the spatial resolution of the outer profile measurement.Nondestructive and co-reference measurements of the inner profile of a target were achieved using the tomographic characteristics of the LDC method.Furthermore,by combining multiple repositionings of the target using a horizontal slewing shaft,the inner and outer 3D surface profiles of the target were obtained,along with a power spectrum assessment of the entire surface.The experimental results revealed that the respective axial and lateral resolutions of the outer profile measurement were 0.5 and 1.3 nm,while the respective axial and lateral resolutions of the inner profile measurement were 2.0 nm and approximately 400.0 nm.The repeatabilities of the rootmean-square deviation measurements for the outer and inner profiles of the target were 2.6 and 2.4 nm,respectively.We believe our study provides a promising method for the high-resolution and nondestructive co-reference measurement of the inner and outer 3D profiles of laser fusion targets.

Isolation, Identification and Characterization of Genes Differentially Expressed between Pima and Upland Cotton Fibers

The demand for high strength fiber in rawcotton has increased because of the widespreaduse of high speed spinning technology in theyarn and textile industry.Improvement ofcotton fiber quality through

Parameters analysis and application of the differential excitation detection technology

A differential excitation probe based on eddy current testing technology was designed. Sheet specimens of Q 235 steel with prefabricated micro-cracks of different widths and of aluminum with prefabricated micro-cracks of different depths were detected through the designed detection system. The characteristics of micro-cracks can be clearly showed after signals processing through the short-time Fourier transform（ STFT）. By changing the parameter and its value in detecting process,the factors including the excitation frequency and amplitude,the lift-off effect and the scanning direction were discussed,respectively. The results showed that the differential excitation probe was insensitive to dimension and surface state of the tested specimen,while it had a high degree of recognition for micro-crack detection. Therefore,when the differential excitation detection technology was used for inspecting micro-crack of turbine blade in aero-engine,and smoothed pseudo Wigner-Ville distribution was used for signal processing,micro-cracks of 0. 3 mm depth and 0. 1 mm width could be identified. The experimental results might be useful for further research on engineering test of turbine blades of aero-engine.

双模态碳量子点间充质干细胞成像及细胞分化研究

目的制备双模态碳量子点(carbon dots,CDs)探针并探索其示踪间充质干细胞(MSCs)的可行性。方法2022年10月至2023年5月,以钆喷酸葡胺、柠檬酸及二乙烯三胺为前驱体,采用水热法合成Gd∶CDs[钆(Gd)掺杂的碳量子点],进行表征并用于MSCs标记及成像。检测不同浓度Gd∶CDs(10、25、50 nmol/L)对MSCs成骨分化及成脂肪分化的影响。结果Gd∶CDs生物安全性好,荧光量子产率为76%,纵向弛豫率为5.5727 mmol^(-1)·s^(-1),具备双模态成像潜力,可用于MSCs标记。不同浓度Gd∶CDs(10、25、50 nmol/L)标记的MSCs经成骨诱导后,吸光度[D(λ)]分别为2.368±0.014、2.253±0.084及2.133±0.127,与对照组D(λ)(2.334±0.062)相比,高浓度Gd∶CDs对MSCs成骨分化有少许影响(P<0.05),中低浓度的Gd∶CDs标记对MSCs成骨分化无明显影响(P>0.05)。不同浓度Gd∶CDs(10、25、50 nmol/L)标记的MSCs经成脂肪诱导后,D(λ)分别为0.274±0.036、0.286±0.032、0.262±0.065,与对照组D(λ)(0.254±0.026)相比,各组对MSCs的成脂肪分化无明显影响(P>0.05)。结论采用水热法制备的Gd∶CDs荧光量子产率及纵向弛豫率高,具有示踪MSCs的潜能,且对MSCs的分化影响较小。

血清GDF5 mRNA在慢性牙周炎患者中的水平及其与病变程度的相关性

目的分析血清生长分化因子5(GDF5)mRNA在慢性牙周炎患者中的水平及其与病变程度的相关性。方法选取2019年1月至2021年1月该院口腔科收治的慢性牙周炎患者150例作为研究组,并根据牙周检查情况分为轻度组(53例),中度组(51例),重度组(46例),另选取同期健康体检者50例作为对照组;采用实时荧光定量聚合酶链反应(qRT-PCR)检测血清GDF5 mRNA水平;采用Pearson相关分析血清GDF5 mRNA水平与牙周袋探诊深度、附着丧失水平和菌斑指数的相关性;采用Spearman相关分析GDF5 mRNA水平与病变程度的相关性;采用多因素Logistic回归分析慢性牙周炎的影响因素;绘制受试者工作特征(ROC)曲线分析血清GDF5 mRNA水平对重度慢性牙周炎的预测价值。结果对照组与研究组GDF5 mRNA水平分别为1.01±0.30、0.70±0.21,研究组明显低于对照组,差异有统计学意义(t=8.061,P<0.001)。血清GDF5 mRNA水平、牙周袋探诊深度、附着丧失水平和菌斑指数在轻度组、中度组和重度组中依次升高,两两组间比较,差异均有统计学意义(P<0.05)。GDF5 mRNA与牙周袋探诊深度、附着丧失水平、菌斑指数、病变程度均呈负相关(r=-0.587、-0.521、-0.628、-0.567,P<0.001)。多因素Logistic回归分析结果显示,GDF5 mRNA水平降低是慢性牙周炎发生的危险因素(P<0.05)。ROC曲线分析结果显示,血清GDF5 mRNA预测重度慢性牙周炎的曲线下面积为0.893,灵敏度为79.23%,特异度为88.31%。结论慢性牙周炎患者血清GDF5 mRNA水平随着病变程度的加重而降低,GDF5 mRNA还可以作为预测重度慢性牙周炎的指标。

新型分子探针PET/CT显像在分化型甲状腺癌中的研究进展

近年来,分化型甲状腺癌(DTC)的发病率呈显著增高趋势,PET/CT在DTC患者诊疗中的应用也备受瞩目,其将解剖学与功能学成像相结合,实现了分子水平可视化。氟18-脱氧葡萄糖(18F-FDG)已被证实为细胞代谢的标志物,是目前使用最广泛的PET放射性药物。除18F-FDG外,多种新型分子探针也有望从基础研究走向临床,用于DTC显像并指导治疗。本文主要阐述了新型PET分子探针的作用机制及研究进展,以期为新型分子探针在DTC诊疗领域的发展与应用提供参考。

基于网络探针的配电网保护5G通信质量监测技术研究

5G技术可为配网差动保护技术应用提供通信解决方案,但5G网络的时延和抖动依然不稳定,影响配网差动保护的正常工作。目前5G配网差动保护应用缺乏对端到端通信链路性能实时、精确监测的手段。文章提出一种在5G终端中对差动保护的特定报文标记时间信息进行网络性能监测的探针技术,并分别基于5G虚拟专网软切片和硬切片的组网方案,验证网络探针技术在差动保护业务中的应用可行性,为5G技术在电力业务中的广泛应用提供保障。

浅谈百兆以太网物理层一致性测试之探头选择

文章通过对比泰克P6247与TDP3500两款差分探头测试百兆以太网物理层一致性的结果,研究不同差分探头对信号幅值测量的影响。实验发现,不同带宽和不同阻抗曲线的探头在测量时,会对待测信号产生影响,使得测量结果存在较大的差异。因此,在选择差分探头进行百兆以太网物理层一致性测试时,需要综合考虑不同指标的影响,选择合适的差分探头以获得更精准的幅度域测量结果。

A new probe for atmospheric electric field mill

A new probe for atmospheric electric field mill is introduced.It consists of three parts：signal acquisition circuit for atmospheric electric field,preamplifier circuit and phase sensitive detection circuit.The signal acquisition circuit adopts the double-stator structure to form differential input circuit,thus double-precision is obtained.Preamplifier circuit is made of current-to-voltage （I-V） conversion circuit,differential amplifier circtuit and secondary amplifying circuit.The polarity of electric field is obtained via phase sensitive detection circuit.Simulation results are obtained using Multisim,and the feasibility of the designed probe is verified.

Regional characteristics and spatiotemporal differentiation of the prevalence of hand, foot, and mouth disease in Xinjiang, China

In recent years,the number of hand,foot,and mouth disease(HFMD)cases in China has continued to grow,and the disease has become a serious public health issue.Xinjiang Uygur Autonomous Region is located in the arid areas of Northwest China,where the epidemiological trend of HFMD is gradually increasing and characterized by geographical heterogeneity.In this study,based on the HFMD case data in all counties and cities in Xinjiang,we employed statistical and GIS spatial analyses,and geographic probe models to characterize the spatiotemporal differentiation of HFMD epidemics in Xinjiang during the period of 2009–2018,and quantitatively analyzed the factors influencing the spatial differentiation of HFMD epidemics.The results showed that HFMD incidence rate in Xinjiang had non-stationary temporal characteristics on the interannual and monthly scales,and the monthly variation characteristics of HFMD epidemic were quite different in southern and northern Xinjiang.The spatial distribution characteristics of HFMD epidemics showed a north–south spatial differentiation pattern with the Tianshan Mountains as the boundary;cold spot and hot spot of HFMD epidemics in Xinjiang have shifted from scattered to concentrated,and the spatial differentiation pattern had gradually stabilized.Moreover,the dominant factors influencing the spatial differentiation of HFMD epidemics in Xinjiang were socioeconomic factors,such as per capita GDP and urbanization rate,while the basic factors affecting its spatial differentiation were natural environmental factors.The spatial differentiation and evolution patterns of HFMD epidemics differed between northern and southern Xinjiang.Specifically,the leading role of socioeconomic factors is more obvious in southern Xinjiang than in northern Xinjiang,while natural environmental factors(e.g.,dryness and relative humidity)contribute to the prevalence of HFMD epidemics in northern Xinjiang,and the perturbing effect of these factors was more prominent than other factors.The results of this study can provide a scientific basis for the prevention of HFMD epidemics and early warning of HFMD epidemics in Xinjiang.

鉴别牛结节性皮肤病病毒双重荧光定量PCR检测方法的建立及应用

为实现牛结节性皮肤病病毒(LSDV)和羊痘病毒属(CaPV)其他成员的鉴别诊断,针对LSDV 010基因保守区域设计特异性引物及TaqMan探针,与文献报道的CaPV 068基因的通用引物及探针组合,通过优化反应体系和条件,建立了一种可同时鉴别检测LSDV和CaPV其他成员的双重荧光定量PCR检测方法。结果显示:本方法可以特异性扩增LSDV和CaPV其他成员,并且与其他牛、羊病毒无交叉反应,特异性好;对pLSDV-010和pCaPV-068质粒标准品的最低检测限均为15 copies/μL,具有较高的灵敏性;组内和组间变异系数均小于1.75%,重复性良好。应用本试验建立的方法与荧光定量PCR方法同时检测542份临床样品,发现CaPV的样品符合率为98.52%,LSDV为99.63%。本试验建立的方法为CaPV鉴别筛查、LSDV精准防控及流行病学调查提供了快捷有效的技术手段。

一种基于交流电磁场的差分检测探头

交流电磁场检测技术近年来广泛应用于各类结构缺陷的无损检测和定量评估中,检测时探头抖动易引起干扰信号而造成的缺陷误判,为解决此问题,提出一种新型的差分检测探头。通过COMSOL软件建立交流电磁场检测探头的有限元仿真模型,探究了提离抖动下特征信号的畸变规律,分析了Bx背景磁场与检测位置的关系;设计了一种基于差分磁传感器的检测探头,搭建缺陷检测系统并进行试验。试验结果表明,提出的差分检测探头能有效抑制提离干扰,增强缺陷信号识别能力,提高检测灵敏度。

基于差动共焦的倾角测量传感器

为了解决传统激光差动共焦显微镜(LDCM)无法在测距的同时,进行高精度倾斜角度测量的问题,提出了一种基于差动共焦的倾角测量传感器。在对倾斜表面进行测量时,该传感器首先利用轴向扫描获取的差动响应信号精准定位其焦点位置,然后分析显微镜光瞳面场强分布并提取光斑图像的峰值位置,从而实现对倾角的精准测量。首先,建立聚焦光束经倾斜待测面反射后的光场分布模型,对不同倾斜角度下显微镜光瞳面的场强分布情况进行分析。然后,在分析倾斜光斑特征的基础上,提出了采用改进Meanshift算法进行光斑峰值位置提取的方法。最后,通过实验验证了传感器对倾角测量的有效性。实验结果表明,传感器对倾斜程度(0~8°)测量平均误差为0.011°,对倾斜方向(0~360°)的测量平均误差为0.128°,能够满足利用差动共焦非接触光学探针对三维表面进行检测的过程中,对待测表面倾斜角度测量的要求。该传感器为自由曲面的高精度轮廓测量提供了一种新的方法。

基于差分柔性涡流探头的铁轨裂纹检测方法

提出了一种基于柔性印刷电路板(FPCB)探头的铁轨表面裂纹检测方法。通过仿真分析和高速转台实验,对不同激励频率、不同深度缺陷以及簇状密集缺陷的探头检测能力展开测试。根据检测结果分析出适合FPCB探头的最佳激励频率以及适用的检测缺陷深度范围,得出FPCB方形线圈检测不同间距密集缺陷的能力与线圈尺寸的对应关系,即:在已知密集缺陷最小间距为X的情况下,将方形FPCB线圈边长设计为2X即可基本识别出全部缺陷,设计在X以内可获得最佳的单线圈检测信号,设计在X/2以内可获得最佳差分检测信号。此结论仅适用于文中研究的方形线圈。

山东省人口老龄化空间格局及影响因素研究

基于第五次、第六次和第七次全国人口普查数据,采用空间自相关、半变异函数法等方法揭示了山东省人口老龄化空间分异特征,并运用地理探测器模型定量识别人口老龄化空间分异的影响因素。结果表明:(1)近20年来,老龄化程度不断加剧,重度老年型成为区域老龄化主导类型;设区市辖区老龄化水平、增量和速度均低于周围县市,都市圈核心区域老龄化水平低于都市圈拓展区。(2)人口老龄化空间正相关性较显著,“高-高”关联区集中在胶东经济圈,“低-低”关联区分布相对分散;空间自相关引起的结构性分异较为明显,随机因素造成的空间变异呈小幅增加的趋势,空间分异度十分明显的方向为东-西方向。(3)出生率、死亡率是老龄化空间分异的主要因素,人口老龄化的空间分异是人口和社会经济因素共同作用的结果,两两因子之间的交互作用能够增强对人口老龄化空间分异的解释力。

基于光声泵浦成像的氧分压测量定量分析

光声泵浦成像是一种新型的高特异性光声分子影像技术.它可以避免常规光声成像中来自血液等强背景信号的干扰,实现组织中微弱目标分子的探测,并通过对泵浦-探测激光间的延时扫描,获得组织中的氧分压分布.本文采用亚甲基蓝作为分子探针,通过对血红蛋白溶液中氧分压变化的监测,开展了对光声泵浦成像的定量分析研究.本文采用高斯噪声模型,获得了三重态差分信号稳定性随着平均次数变化的规律,并在此基础上对氧分压测量的误差进行了分析.结果表明,在平均次数为200次条件下,氧分压在300—550 mmHg(1 mmHg=133 Pa)区间内,所搭建系统的检测精度优于33 mmHg.本研究将对光声泵浦成像技术的进一步发展和应用起到重要的指导作用.

Water–soluble and polarity–sensitive near–infrared fluorescent probe for long–time specific cancer cell membranes imaging and C. Elegans label

A novel D–π –A structure and near–infrared fluorescent probe(DCITT) with high polarity sensitivity and membrane targeting was reported. The fluorescent spectra of DCITT were polarity dependent and Stokes shift was greater than 300 nm. Due to its high fluorescence quantum yield, low cytotoxicity and photostability, DCITT could be used as a labeling probe in multicellular organisms. In particular, DCITT effectively distinguished tumor cells from normal cells because it could specifically light up the cancer cells membrane based on strong red fluorescence for a long time. On this basis, a polar–sensitive cell membrane probe is developed to differentiate tumor cells from normal cells, which provides an idea and method for the early diagnosis of tumor at cellular level.

基于温度补偿的电阻探针腐蚀监测原理的研究

基于温度补偿的原理,对引起电阻探针腐蚀监测数据波动的关键因素进行了大量研究和分析,发现异种金属间的接触电势和温差电势差,是造成测量数据温度漂移的主要原因.文中通过特殊的电路设计,采用交变激励源对温漂效应进行补偿,极大降低了电阻探针内部接触电势产生的温差效应,使腐蚀速率的测量精度显著提高.现场和实验室测量表明:其电阻分辨率可达到0.5μΩ,腐蚀速率灵敏度达到了0.1μm/a.

多功能墙体探测仪的设计方法

针对墙体中水管、电线、金属物体的探测问题,设计了3种无源传感器,并设计了相关数据处理方法以确定被测物体的中心位置。利用PCB覆铜,制作了用于探测水管的电容极板以及用于探测电线的金属天线。建立了水管检测模型,得到输出信号随被测物体位置的变化规律。基于差分探头模型,提出了一种利用PCB线圈作为敏感单元的金属探测方法,通过数值计算,保证了差分线圈的平衡。最后,针对上述传感单元,设计了被测物体的中心检测算法。测试数据表明,各传感单元均具有较大的探测深度,中心检测误差均在合理范围之内。