Nondestructive and active interrogation system for special nuclear material:proof of principle and initial results

Herein,we employ the threshold energy neutron analysis(TENA)technique to introduce the world's first active interrogation system to detect special nuclear materials(SNMs),including U-235 and Pu-239.The system utilizes a DD neutron generator based on inertial electrostatic confinement(IEC)to interrogate suspicious objects.To detect secondary neutrons produced during fission reactions induced in SNMs,a tensioned metastable fluid detector(TMFD)is employed.The current status of the system's development is reported in this paper,accompanied by the results from experiments conducted to detect 10 g of highly enriched uranium(HEU).Notably,the experimental findings demonstrate a distinct difference in the count rates of measurements with and without HEU.This difference in count rates surpasses two times the standard deviation,indicating a confidence level of more than 96% for identifying the presence of HEU.The paper presents and extensively discusses the proof-of-principle experimental results,along with the system's planned trajectory.

Rapid interrogation of special nuclear materials by combining scattering and transmission nuclear resonance fluorescence spectroscopy

The smuggling of special nuclear materials(SNMs)across national borders is becoming a serious threat to nuclear nonproliferation.This paper presents a feasibility study on the rapid interrogation of concealed SNMs by combining scattering and transmission nuclear resonance fluorescence(s NRF and t NRF)spectroscopy.In s NRF spectroscopy,SNMs such as^(235,238)U are excited by a wide-band photon beam of appropriate energy and exhibit unique NRF signatures.Monte Carlo simulations show that one-dimensional scans can realize isotopic identification of concealed^(235,238)U when the detector array used for interrogation has sufficiently high energy resolution.The simulated isotopic ratio^(235U/238)U is in good agreement with the theoretical value when the SNMs are enclosed in relatively thin iron.This interrogation is followed by t NRF spectroscopy using a narrow-band photon beam with the goal of obtaining tomographic images of the concealed SNMs.The reconstructed image clearly reveals the position of the isotope^(235)U inside an iron rod.It is shown that the interrogation time of s NRF and t NRF spectroscopy is one order of magnitude lower than that when only t NRF spectroscopy is used and results in a missed-detection rate of 10^(-3).The proposed method can also be applied for isotopic imaging of other SNMs such as^(239,240)Pu and^(237)Np.

A review on novel activation strategy on carbonaceous materials with special morphology/texture for electrochemical storage

Various novel carbonaceous materials including carbon nanotubes,nano-onions,carbon microspheres,graphene nanosheets,and carbon microfibers with unique properties,such as tunable surface area and pore size,high chemical stability,cost-effective and facile preparation,have attracted enormous interest for many applications.Also essential,the activation processes play a critical role to achieve these valuable properties.In this review,we provide a thorough analysis of the emerging nano-and microscopic carbon species with special morphology/textures and currently available types of chemical activation agents,and novel activation strategy to enhance electrochemical performance of activated carbon material in electrical energy storage devices including supercapacitor and alkaline ions batteries.A particular emphasis is set on recent advance in activated carbon materials with special morphology/textures for supercapacitors and sodium ion batteries.

Development of Specialized Courses and Establishment of Teaching Materials in Nursing of Integrated Chinese and Western Medicine

Since the Third Plenary Session of the 11 thCentral Committee of the Communist Party of China( CPC),with the promotion and development of traditional Chinese medicine(TCM),the pace of TCM nursing work has been accelerated in nationwide,and a group of integrated Chinese and western medicine nurses have been cultivated preliminarily. However,professional nurses of integrated Chinese and western medicine are still deficient extremely. The target of talent cultivation,based on the theory of "focusing on humanism,expanding diathesis,and enhancing practice to highlight the accommodation and integration of nurses of integrated traditional Chinese and western medicine",is to cultivate competent,practical and interdisciplinary senior nursing talents with strong professional basis,skilled operations,rich humanistic literacy,and sharp innovative spirit who not only master modern nursing knowledge and skills,but also can perform comprehensive nursing under the guidance of TCM theory of holistic concept and syndrome differentiation and nursing. This study,through investigating and analyzing the settings of3-year nursing professional courses in about 20 senior medical colleges,including senior nursing education of TCM,reformed the development of professional nursing courses of integrated Chinese and western medicine and the establishment of educational materials according to the course settings and educational work modes,so as to analyze the current status of nursing education of integrated Chinese and western medicine,determine course targets,and establish course system and educational work modes.

Editorial: Special subject on the mechanical behavior of thermal protection materials and structures

The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.

Preface to the Special Issue on Perovskite Semiconductor Optoelectronic Materials and Devices

Halide perovskite,a novel semiconductor material,was initially used in solar cells since 2009,and tremendous progresses have been witnessed in the last decade.The power conversion efficiency of the single perovskite solar cells has been incredibly increased up to 25.2%,and close to 30%efficiency was realized in perovskite/silicon tandem solar cells.Recently,the application of perovskite has been extended to the light-emitting diodes and photo-detectors.

Innovations of Agricultural Scientific Research Institutions in Management of Special Materials

In recent years,the Ministry of Agriculture has increased input in agricultural scientific research projects.As a result,the procurement amount and quantity of special materials are increasing gradually,and the management of special materials becomes more standardized.In order to do well in management of special materials,the authors made exploration and thinking about further strengthening management of special materials in combination with actual conditions,including establishing regulations and systems,enhancing procurement process,strengthening requisition and safekeeping,and reinforcing general ledger management of special materials.

Guest Editorial——TTA Special Section on Terahertz Materials and Devices

Lying between radio frequency and infrared radiation, terahertz （THz） wave encounters lots of difficulties to produce, detect, transmit, and modulate. Great efforts have been made to construct THz devices, including sources, detectors, switches, modulators, lenses, and filters. However, only moderate progresses have been made in THz generation and detection. Furthermore, the devices and techniques to control and manipulate THz waves are still in its infancy. Therefore, it is still a challenge to date to develop sophisticated THz application systems such as communication, sensing, safety inspection, imaging and medical diagnose systems. This difficult position of THz wave is essential due to the deficiency of THz materials having a suitable THz electromagnetic response, as compared to its neighboring microwave and infrared regime. Practicable material will largely push the THz technology to real-world applications. The GaAs/AlxGa~_xAs material system, for example, is the heart of THz quantum cascade lasers. High quality NbN films, again, set the basis of THz hot electron bolometer.

Preface to Special Topic:Graphene and 2D Materials for Energy Storage

Graphene, a single layer of graphite, has been one of the first real two dimensional （2D） materials isolated in 2004. Thus, graphene is becoming a cutting edge material that opens up new horizons to a whole family of 2D materials beyond the limited current applicability of graphene. The unique advantages of graphene and analogue 2D materials, such as atomic-scale thickness, high specific surface area, mechanically flexible robustness, superior storage capacity, endow them as high-performance electrodes lbr electrochemical energy storage devices. Although it is hard to say whether or not graphene and 2D materials will be implemented in future energy technologies, the recent achievements in this field demonstrate that their roles will be noticeable in the near future.

Preface to Special Issue on Carbon Materials for Energy Application

The rising cost and limited availability of fossil fuels, and the increasing concerns related to their role on global pollution and greenhouse effect have pushed considerably the need to accelerate the transition to a more sustainable use of energy based largely on renewable energy sources. Nanocarbon materials play a critical role in this transition, as they are the key materials for components of different devices necessary in enabling this transition （batteries, fuel cells, solar cells, etc.）. This issue collects 22 contributions, including one perspective and six review papers on the topic of carbon materials for energy applications, written by well-known experts in this field. It is really an exciting special issue that gives a very updated view of this topic, as well as trends and outlooks in this breakthrough research area. The initial perspective paper introduces the different possibilities offered from the growing level of knowledge in this area, testified from the exponentially rising number of publications. It also discusses the basie concepts for a rational design of these nanomaterials. The lk）llowing six reviews address different specific aspects of synthesis, characterization and use of carbon nanomaterials, from fuel cells to composite electrodes, supercapacitors and photoelectrochemical devices for CO2 conversion. These reviews represent an unique opportunity for the readers to be updated on the latest developments of new carbon families such as fullerene, grapbene, and carbon nanotube, and their derived nanocarbon materials （from carbon quantum dots to nanohorn, nanofiber, nano ribbon, etc.）. Second generation nanocarbons, including modification of these nanocarbons by surface functionalization or doping with heteroatoms to create specific tailored properties, and nanoarchitectured supramolecular hybrids, are also discussed. Finally, 1 communication and 14 full articles discuss several aspects of the use of these nanocarbon materials to develop new catalysts for a range of applications （from biomass conversion to Fisher-Tropsch reaction and electrochemical devices） and new materials for energy storage and conversion （adsorption pumps, Li-ion and Li-S batteries, electrodes for electrochemical uses）. We thus believe that this special issue dedicated to the use and development of carbon materials for energy applications represents a unique occasion for young and experienced researchers as well as for managers in the field of sustainable energy to have an updated view on this enabling topic for the future of our society. We thus invite all to have this special issue as a privileged component of your bookshelf.

Special Issue on New Concepts and Advances in Photocatalytic Materials for Sustainable Energy

The use of solar energy to drive the chemical and energy processes,and the chemical storage of solar energy are the key elements to move to a low-carbon economy,sustainable society and to foster energy transition.For this reason,there is a fast-growing scientific interest on this subject,which is part of the general effort for a solar-driven chemistry and energy,the chemistry of the future.To realize this

Thermodynamically Revealing the Essence of Order and Disorder Structures in Layered Cathode Materials

Layered transition metal(TM) oxides are one of the most widely used cathode materials in lithium-ion batteries. The atomic configuration in TM layer of these materials is often known to be random when multiple TM elements co-exist in the layer(e.g. Ni, Co and Mn). By contrast, the configuration tends to be ordered if the elements are Li and Mn. Here, by using special quasi-random structures(SQS) algorithm, the essential reasons of the ordering in a promising Li-rich Mn-based cathode material Li2MnO3 are investigated. The difference of internal energy and entropy between ordered and disordered materials is calculated. As a result, based on the Gibbs free energy, it is found that Li2MnO3 should have an ordered structure in TM layer. In comparison, structures with Ni-Mn ratio of 2:1 are predicted to have a disordered TM layer, because the entropy terms have larger impact on the structural ordering than internal energy terms.

PP-RCT管材专用料的结构与性能研究

采用^(13)C NMR,FTIR,DSC,GPC等技术对北欧化工的RA140E、RA7050、燕山石化BR4101 3种PP-RCT管材专用料的结构和性能进行研究。表征结果显示,RA140E管材专用料乙烯含量最高,且乙烯长链数量少、分布好,综合性能最好;3种牌号管材料的重均相对分子质量均大于5×10~5,RA140E的相对分子质量分布最宽,加工性能最好;RA140E刚-韧平衡性最佳,具有良好的高温耐蠕变性能。

如何通过收听VOA Special English来提高英语听力

听是人们获取信息的重要手段之一 ,但听力却是学习英语的中国学生的一个弱项。听力的提高是一个循序渐进的过程 ,这必须以适当的材料为基础 ,以长期的努力作保障。本文试图通过评介美国之音特别英语节目 ,以期找到一条提高听力的切实可行的、可持续发展的途径。

The Way to Improve the Teaching Quality of the Special English Curriculum for Medical Laboratory Science

Phenomenon: Nowadays, with rapidly developing in medical laboratory science(MLS), new concepts, knowledge and technologies are constantly emerging, which requires medical students to continuously learn to grasp the new development trend and the latest research progress. To enable the students to learn and make use of scientific knowledge better, the Special English Curriculum for MLS has been set up, which is very important to non-English-speaking students. However, there are many problems in the course of teaching, so the improved teaching quality of the curriculum is in demand. Approach: In this paper these problems are described and the corresponding advices are proposed from the perspectives of staff room, teachers and students, which are supposed to develop the curriculum for education of the medical laboratory scientists. Findings: To improve the teaching quality of the Special English Curriculum for MLS, the textbook should be appropriately selected or compiled, the novel teaching methods can be applied, and the modern multimedia teaching materials can be adopted.The teachers of the curriculum should be proficient in professional knowledge, English as well as the systematic and scientific teaching methods. The students need to have the courage and determination to overcome the difficulties when they learn the curriculum, and the students who have not did well in their lessons should learn to study by themselves. Insights: The Special English Curriculum for MLS is very important to non-English-speaking students and is kind of difficult for them, the staff room, teachers and students should adjust themselves to teach and learn the curriculum better.

两种PP-RCT专用料的性能对比

选取国产、进口两个牌号的结晶改善无规共聚聚丙烯(PP-RCT)专用料,对其力学性能、结晶熔融状态、流变性能进行对比分析。结果表明:与普通无规共聚聚丙烯(PPR)专用料相比,PP-RCT专用料的常温简支梁冲击强度高达80 kJ/m ^(2)以上,热变形温度达75℃以上,拉伸屈服强度略有提升,管材耐热水性能大幅提升。国产、进口PP-RCT专用料在多种形态的差示扫描量热仪(DSC)曲线下都能显示明显的双熔融峰,并且β峰为主峰,对应到广角衍射数据,β晶含量为40%~80%。管材静液压测试数据显示,国产、进口PP-RCT专用料的耐压时间、承压等级相当。

双工位针刺机器人系统设计

针对单工位针刺成型系统中人和机器无法高效协同生产,预制体生产效率较低;现有的直线型双工位针刺机器人设备需要2个外部回转轴带动双工位参与织物针刺,系统编程难度较高,且工位切换时需要占据的空间大的问题。提出一种混合切换双工位针刺机器人系统,并开展了双工位针刺成形系统的机械结构设计、异型预制体模具和针刺工艺设计、控制系统设计、运动仿真以及预制体制备的实验验证。结果表明:系统成功实现了大尺寸异型曲面预制体的高效针刺成形,直线/旋转混合切换的双工位使得实现预制体的自动换装的同时又能保证系统空间占用量小;双工位中只有针刺工位上的外部回转轴与6关节机械臂联动,系统较为简单,编程方便;同时提高了数控回转工作台的承载力且将针刺末端执行器的布针数量增加至25针,满足了大尺寸预制体的针刺成形,并使得针刺成形效率直接提高2倍。本文系统可应用于批量化制备大尺寸异型曲面复材预制体。