Determination of the embedded electronic states at nanoscale interface via surface-sensitive photoemission spectroscopy

The fabrication of small-scale electronics usually involves the integration of different functional materials. The electronic states at the nanoscale interface ...     

基于Agent的分布式网络测量与分析系统研究

分布式的Internet网络测量和分析技术已成为目前网络行为学研究的热门课题之一。文章提出了一种基于A-gent的分布式网络测量和分析模型系统,并且详细地介绍了这种系统的具体实现方法。     

Rapid Detection of Wheat Blast Pathogen Magnaporthe oryzae Triticum Pathotype Using Genome-Specific Primers and Cas12a-mediated Technology

Wheat blast, caused by the fungus Magnaporthe oryzae Triticum (MoT) pathotype, is a devastating disease persistent in South America and Bangladesh. Since MoT generally fails to cause visual symptoms in wheat until the heading stage when the infection would have advanced, disease control by fungicide application solely based on the detection of visual symptoms is ineffective. To develop an accurate and sensitive method to detect MoT at the seedling and vegetative stages for disease control, we sequenced the genomes of two MoT isolates from Brazil and identified two DNA fragments, MoT-6098 and MoT-6099, that are present in the MoT genome but not in the genome of the rice-infecting Magnaporthe oryzae Oryzae (MoO) pathotype. Using polymerase chain reaction (PCR), we confirmed the specificity of the two markers in 53 MoT and MoO isolates from South America and Bangladesh. To test the efficiency of the two markers, we first established a loop-mediated isothermal amplification (LAMP) method to detect MoT at isothermal conditions, without the use of a PCR machine. Following this, we used the Cas12a protein and guide RNAs (gRNAs) to target the MoT-6098 and MoT-6099 sequences. The activated Cas12a showed indiscriminate single-stranded deoxyribonuclease (ssDNase) activity. We then combined target-dependent Cas12a ssDNase activation with recombinase polymerase amplification (RPA) and nucleic acid lateral flow immunoassay (NALFIA) to develop a method that accurately, sensitively, and cost-effectively detects MoT-specific DNA sequences in infected wheat plants. This novel technique can be easily adapted for the rapid detection of wheat blast and other important plant diseases in the field.     

C含量对断路器用紫铜表面Ti感应熔覆层组织及硬度的影响

对Ti/石墨粉末进行高频感应处理,使其发生熔融到断路器用紫铜表面得到Ti熔覆层,分析了C含量对其组织及硬度的影响。研究结果表明:所有感应熔覆层都形成了TiC成分对应的衍射峰,在熔覆阶段Ti和石墨反应后转变为TiC。加入不同含量C后获得具有同样成分的熔覆层,提高C加入量后形成了更强的TiC衍射峰,形成了较为平整的熔覆层,并且获得了致密组织结构,整体厚度分布较为均匀,跟基体之间属于一种冶金结合状态。随着C加入量提高已观察不到短纤维形态,形成了许多等轴形态TiC。在过渡区中形成了具有短纤维结构TiC,呈现均匀的分布形态。提高C含量后,获得了显微硬度更大的Ti感应熔覆层,熔覆层组织中生成了更多TiC,使熔覆层获得更高硬度。     

Atomically Dispersed Sn Confined in FeS2 for Nitrate-to-Ammonia Electroreduction

Electrocatalytic NO₃⁻ reduction to NH₃ (NO₃RR) is an efficient strategy to simultaneously mitigate NO₃⁻ contamination and produce sustainable NH₃. Herein, atomically dispersed Sn confined in FeS₂ (Sn-FeS₂) is reported as an effective and robust NO₃RR catalyst, achieving a maximum NH₃-Faradaic efficiency of 96.7% with a corresponding NH₃ yield rate of 15.8 mg h⁻¹ cm⁻², along with an excellent catalytic stability. Atomic coordination characterizations of Sn-FeS₂ unravel that single-atomic Sn bonds with the surrounding Fe atoms to construct the unique p-d hybridized Sn-Fe pair sites. Combining theoretical investigations and operando spectroscopic measurements unveil that Sn-Fe pair sites can synergistically promote the NO₃⁻ activation and N═O bond dissociation, accelerate the protonation energetics of NO₃⁻-to-NH₃ pathway and suppress the competing hydrogen evolution, eventually drastically enhancing the NO₃RR activity and selectivity.     

Epitaxial Growth of 1D Te/2D MoSe2 Mixed-Dimensional Heterostructures for High-Efficient Self-Powered Photodetector

Mixed-dimensional heterostructures provide additional freedom to construct diverse functional electronic and optoelectronic devices, gaining significant interest. Herein, highly-aligned pseudo-1D tellurium is epitaxially grown on 2D monolayer transition metal dichalcogenides (TMDs), including MoSe₂, MoS₂, and WS₂. A one-pot chemical vapor deposition (CVD) technique eliminates the normally required transfer steps, thereby producing mixed-dimensional heterostructures with an ultraclean interface. The controllable epitaxial growth of Te/TMD heterostructures are verified by Raman, scanning probe microscopy (SPM), and transmission electron microscopy (TEM) observation. The photoluminescence results indicate that the emission from TMDs is quenched in the heterostructure, confirming the efficient transfer of photogenerated carriers from TMDs to Te. Additionally, the mixed-dimensional p-n Te/MoSe₂ heterojunction photodetector presents self-driven behavior with high responsivity (328 mA W⁻¹), external quantum efficiency (79%), and specific detectivity (8.2 × 10⁹ Jones). The modified facile synthesis strategy and proposed growth mechanism in this study shed light on synthesizing mixed-dimensional heterojunctions. This opens avenues for fabricating functional devices with reduced sizes and high densities, further enabling miniaturization and integration opportunities.     

基于YOLOv3的无人机建筑物空间特征提取方法研究

随着智慧城市的发展,对建筑空间特征的采集速度和精度要求越来越高,针对市面上常见的空间特征提取方法灵活性差、智能化程度低、人力成本高等问题,本文提出了一种基于无人机扫描与YOLO识别的检测方法,完成了建筑物窗户构件的实时识别与提取。本文对YOLOv3算法进行了优化调整并运用自制的数据集对算法模型进行训练,使用Nginx搭建RTMP(Real Time Messaging Protocol)推流服务器接收无人机扫描信息,在地面平台显示实时识别结果,该方法大大提高了识别效率,降低了推流传输延迟,在无人机检测实验中体现出了实时、高效、智能的特点,借助无人机的灵活性,能够高效地满足建筑构件实时检测的需要。     

基于SCA波形采样读出电子学的CSNS Back-n中子飞行时间测量

中国散裂中子源(CSNS)反角白光中子束线(Back-n)对中子核数据测量和核技术应用等多个领域均有重要意义。为监测其中子束斑轮廓、束流密度及束流能量,研制了由镀硼微网格气体(Micromegas)探测器构成的束流剖面监测装置,并通过测量中子的飞行时间(TOF)来获得能量信息。采用基于开关电容阵列(SCA)专用集成电路(ASIC)的波形采样电子学系统,实现了128路Micromegas探测器阳极条信号的低噪声放大、成形和波形数字化,在现场可编程逻辑门阵列(FPGA)芯片中实现了对信号过阈时间的实时测量,其量程为650 ns～10 ms,电子学时间分辨好于10 ns。在CSNS Back-n上开展实验,成功获得了中子束流剖面及10.65μs～10 ms范围的飞行时间谱,对应的中子能量范围约为0.16 eV～0.14 MeV。利用钽、钴等吸收体进行了中子共振吸收峰的检验,验证了读出电子学系统的功能及飞行时间测量的正确性。     

A novel three-step approach to separate cathode components for lithium-ion battery recycling

Lithium-ion batteries(LIBs) represent efficient energy storage technology that can help to alleviate fossil fuel-based CO_2 emissions.Presently,LIBs are being applied extensively in consumer electronics and electric vehicles,but because of limited resources,there is an urgent need for spent LIB recycling technologies.The complexity of LIBs,especially the electrode part,makes it difficult to achieve precision separations for each single component from the used electrode with low emissions.Herein,we propose a three-step treatment for the separation of cathode components.In detail,detaching of the current collector from the cathode is accomplished by the solvent method,which was found to be an ideal strategy compared with previous reports.Then,a thermal treatment is used to remove the polymer binder in the second step because we demonstrated that it is challenging to separate polyvinylidene fluoride(PVDF) from other cathode components by dissolution with N-methylpyrrolidone.The separation efficiency between the active material and conductive carbon by the polymer solution in the third step showed reasonably good results.We anticipate this work will serve as an important reference for the separation of each single electrode component in both laboratory-and industrialscale applications.Separation of binder and development of novel binders,which can be easily recycled for sustainable LIBs,are fruitful areas for further research.