最新刊期
卷 44 ， 期 8 ， 2021
- “在上海同步辐射光源，利用共聚焦μ-SRXRF技术，成功对生物样品体内化学元素进行原位分析，为生命和环境研究提供新方法。”摘要：BackgroundSynchrotron radiation confocal micro X-ray fluorescence (confocal μ-SRXRF) micro-probe is a three dimensional analytical method for detecting chemical elements with depth resolution. It can be used to obtain the chemical element information at different depths of samples in situ, which is suitable in the fields of life and environmental sciences.PurposeThis study aims to apply the confocal μ-SRXRF device and in-situ cryogenic device, developed at the hard X-ray micro-focusing beamline (BL15U1) of Shanghai Synchrotron Radiation Facility (SSRF), to analyze the in vivo chemical elemental imaging of biological samples.MethodsConfocal μ-SRXRF was based on K-B mirrors and polycapillary X-ray optics. The foci of the polycapillary X-ray optics and the incident X-ray beam were coincident by continuous scanning and position modification. The confocal μ-SRXRF was used for in-situ XRF imaging analysis of Arabidopsis thaliana seeds and Daphnia magna, and compared with that of conventional μ-SRXRF. The confocal volume was submerged at different depths within the samples to obtain the depth-dependent information. In addition, an in-situ cryogenic device was used to keep Daphnia magna under the cryogenic environment.ResultsThe spatial distributions of chemical elements for in vivo biological samples were directly obtained by confocal μ-SRXRF, without slicing or drying. The specific distribution of chemical elements in plant tissues or organs is more accurately obtained while the absorption and distribution characteristics of chemical elements in organisms are observed more carefully.ConclusionsConfocal μ-SRXRF can be used to directly and effectively analyze the spatial distribution of chemical elements within biological samples. Meanwhile, it can be expanded to analyze the heat-sensitive biological samples and chemical elements by equipping with in-situ cryogenic device, providing a powerful in-situ characterization technique for the life and environment research.关键词：Synchrotron radiation;Confocal micro X-ray fluorescence technique;In-situ cryogenic device
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发布时间：2024-10-25 - “最新研究报道，钒掺杂钴-氮-碳催化剂在氧还原电催化领域取得突破，为替代铂基材料提供新思路。”摘要：BackgroundTransition metal nitrogen doped carbon materials are promising to replace precious metal platinum-based materials as an important electrocatalyst for oxygen reduction, and have attracted extensive attention in the research fields of energy storage materials and energy conversion devices.PurposeThis study aims to develop new vanadium doped transition metal carbon materials with excellent catalytic performance, and clarify the role of the introduced of vanadium.MethodsThe vanadium doped cobalt-nitrogen-carbon catalyst was designed by two-step pyrolysis method and impregnation method. The catalytic performance of the oxygen reduction reaction (ORR) was evaluated by a three electrode system using rotating disk electrode. The morphology and microstructure of catalysts were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) was employed to examine crystal orientation structure of catalyst whilst the element types and distribution of materials was analyzed by X-ray photoelectron spectroscopy. Finally, Co K-edge and V K-edge X-ray absorption fine structure (XAFS) spectroscopy were used to determine the local atomic configuration and electronic structure.ResultsThe experimental results show that vanadium doped cobalt-nitrogen-carbon catalyst exhibits superior ORR performance than the traditional cobalt‒nitrogen‒carbon catalyst. XAFS spectra clarifies that the electronic state of cobalt is changed by the introduction of vanadium, and the catalytic performance is further enhanced.ConclusionThe performance of Co‒N‒C catalyst is regulated by the high-valence state V doping, which provides an idea for the design of high-efficiency oxygen reduction catalyst.关键词：Oxygen reduction reaction;Non-precious metal catalysts;X-ray absorption fine structure;Metal doping
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发布时间：2024-10-25
SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS
- “俄罗斯NICA-MPD电磁量能器研究取得新进展，模拟分析了影响其性能的多个参数，为探测器设计提供参考。”摘要：BackgroundThe Shashlik electromagnetic calorimeter (ECAL) is used in the Nuclotron-based Ion Collider Facility's MultiPurpose detector (NICA-MPD) of the Russian heavy ion superconducting synchrotron. It is designed as a cylindrical barrel divided into 32 sectors with a total of 43 008 towers. Each tower is composed of 220 layers of lead and 221 layers of scintillator alternately.PurposeThis study aims to simulate multiple parameters of Shashlik ECAL for NICA-MPD that affect the performance of ECAL.MethodsFirst of all, the module of ECAL tower was built based on the principle of Shashlik ECAL. Then, the GEENT4 software was employed to simulate the performance of every single tower of ECAL according to its structure composition. Considering the influence of the design parameters of the scintillator and absorber on energy deposition, energy resolution, and energy leakage after electrons were incident on the tower and the subsequent scintillator luminescence process, the influence of the reflective layer on the number of photons was in the wavelength shifted fiber and detector. Finally, factors that affected energy deposition, energy leakage, energy resolution, and photon number in the wavelength shift (WLS) and sensor, and the influence of the thickness, number of layers, and size of the scintillator and absorber in the module on energy deposition, energy leakage, and energy resolution were simulated and analyzed.ResultsThe simulation results show that the best side length of cross-section of each tower is 4 cm. When the total thickness of absorber and scintillator is 1.8 mm and the thickness of lead absorber is 0.3 mm, the energy resolution meets the experimental requirements of 5%@3 GeV. When the radiation length reaches 13X0, maximum energy deposition and obtains better energy resolution can be achieved. Adding a reflective layer to the tower side can increase the number of photons in the fiber by 10%~19% whereas adding a reflective coating to the fiber end can effectively increase the number of photons reaching the detector by 50%.ConclusionsThe photon numbers in the wavelength shift fiber and the detector are affected by the reflection layer on both the tower side and the end face of the fiber. The importance and necessity of adding reflector are verified by this study.关键词：Electromagnetic calorimeter;GEANT4 simulation;Energy deposition;Energy resolution;Energy leakage
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发布时间：2024-10-25 -
A biometrics recognition instrument using X-ray phase contrast imaging for biosafety inspection AI导读
“在海关生物安全检测领域，专家研制了基于相位衬度成像的X射线生物特征识别仪，为解决生物样本检测问题提供新手段。”摘要：BackgroundCustoms biosafety inspection is of great significance for maintaining ecological balance and protecting rare wild animals and plants.PurposeTo overcome the problem of poor contrast in traditional X-ray imaging systems for customs biosecurity inspections, an inspection instrument based on X-ray phase contrast imaging planned to be developed in this work.MethodsThe on-line phase contrast imaging method with high photon utilization efficiency was adopted in order to meet the requirements of high-efficiency data acquisition and fast imaging for the customs inspection. The protective shed shielding, security linkage and automatic sample stage were used in the instrument to ensure radiation safety in the inspection and the convenience of sample switching and adjustment. The methods of phase contrast micro-CT and three-dimensional micro-structure quantitative analysis were applied for biometrics recognition of specimens.ResultsA biometrics recognition instrument based on X-ray phase contrast imaging is developed. The test results of JIMA chart and actual samples show that the spatial resolution of the instrument is 3 μm and that the instrument enables high contrast imaging and quantitative analysis of weakly absorbing samples and can be used for the inspection of most biological specimens.ConclusionsThe instrument developed in this work provides a new tool for customs biosafety inspection. Due to its phase contrast imaging characteristics, the instrument can also be applied to the research of microscopic identification of Chinese medicinal materials, structural pharmaceutics and polymer materials.关键词：X-ray phase contrast imaging;Micro-CT;Micro-focus X-ray tube;Biosafety inspection- 439
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发布时间：2024-10-25 - “在金属材料微观结构研究领域，专家利用透射电子显微镜分析氩离子辐照对纯镍薄膜的影响，发现辐照剂量不同，缺陷类型和尺寸变化明显，为理解辐照损伤效应提供新见解。”摘要：BackgroundNickel -based superalloys are widely used in high temperature structural materials and have important applications in nuclear materials. Radiation damage characteristics are the key factors to evaluate the properties of nuclear materials.PurposeThis study aims to investigate the effect of ion irradiation on the microstructure of metal materials.MethodsThe annealed pure nickel block was preliminarily cut into thin foils and pre-thinning. Then, the pit thinning, twin-jet electropolishing and other processes were applied to further thin the foil samples until they became electron-lucent. The pure nickel foils were irradiated by 120 keV argon ions (Ar+) with three different doses. The irradiation defects and deformed structures in the pure nickel foils were characterized by transmission electron microscope.ResultsThe pure nickel foils have significant radiation damage after the Ar+ irradiation. At the low Ar+ irradiation dose, the irradiation defect clusters are dominated by black spot defects, which contained a large number of stacking fault tetrahedrons. The void defects occur at the relatively high Ar+ irradiation dose. With the increase of Ar+ radiation dose, the number density of void defects increases, while the size of void defects increases first and then decreases.ConclusionsUnlike bulk pure nickel, the argon ion irradiation with relatively high dose is able to induce expansion dislocation and deformation twin in the pure nickel foils. This is because the decrease of material size can weaken its symmetry and inhibit the initiation of the dislocation slip system.关键词：Argon ion;Pure nickel foil;Microstructure;Defect clusters;Deformation twins
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发布时间：2024-10-25
ACCELERATOR, RAY TECHNOLOGY AND APPLICATIONS
- “在神经内分泌肿瘤显像领域，研究人员设计合成了新型生长抑素类似物Gluc-Lys（［Al18F］NOTA）-KE108探针，为SSTR阳性肿瘤显像提供新方法。”摘要：BackgroundRadionuclide labeled somatostatin analogs can specifically bind to somatostatin receptors (SSTRs) on the cell surface of neuroendocrine tumors (NETs), hence be used for imaging or treatment of NETs.PurposeThis study aims to label glycosylated KE108 protein with 18F nuclide, and to investigate the distributions and PET imaging of this probe in mice in vivo.MethodsA novel 18F-radiolabeled somatostatin analogue probe Gluc-Lys([Al18F]NOTA)-KE108 was designed and synthesized, which linked 18F nuclide and glycosylated KE108 protein by coupling bifunctional chelator (NOTA) to target SSTR positive tumors. The in vitro physicochemical properties, in vitro cell binding, ex vivo biodistribution and in vivo imaging of Gluc-Lys([Al18F]NOTA)-KE108 were further investigated to evaluate the SSTR targeting ability and feasibility of PET imaging in the diagnosis of NETs.ResultsThe efficiency of Gluc-Lys([Al18F]NOTA)-KE108 obtained with moderate labelling is (30±5)% without corrected (n=6), and the radiochemical purity is higher than >95%. The radiochemical yield is ((20±5)%, uncorrected) (n=6), and the total synthesis time is about 20 min. The specific activity is more than 1.37 GBq∙μmol-1. The probe shows expected nanomolar binding affinity in SSTR-positive AR42J and BON1 tumor cells, which Kd values are (152.3±49.1) nmol∙L-1 and (45.5±13.6) nmol∙L-1, respectively, and can be specifically inhibited, showing high SSTR targeting ability. In PET imaging of AR42J tumor bearing mice, Gluc-Lys([Al18F]NOTA)-KE108 has a high uptake of radioactivity and a high ratio of tumor to muscle uptake.ConclusionsGluc-Lys([Al18F]NOTA)-KE108 has high hydrophilicity and good stability in vitro, hence be served as a potential imaging agent for SSTR-positive tumors.关键词：Somatostatin Receptor (SSTR);Complex aluminum fluoride;Neuroendocrine tumors (NETs);KE108 peptides
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发布时间：2024-10-25
NUCLEAR CHEMISTRY, RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE
- “在电子学领域，专家提出迭代法解决电路模型初值问题，为电路分析提供新思路。”摘要：BackgroundAnalyzing the nuclear electrical circuit in time domain can help to obtian the voltage value at any moment based on the appropriate initial voltage by using recursive method.PurposeThis study aims to obtain the correct output waveform of nuclear signal forming circuit by using iteration method instead of recursive method.MethodsFirst of all, the circuit current equation and the S-K low-pass filter circuit equivalent model were established according to Kirchhoff's current law (KCL) and node voltage method. Then the resistant devices were converted to non-resistant devices by equivalent substitution, and the digital solution was obtained by the iterative method. Finally, ihe initial value problem of recursive method was discussed, and the errors between recursive solution and iterative solution of C-R differential circuit and R-C integral circuit in nuclear signal forming circuit were analyzed.ResultsComparison results verify that the iterative method can solve the initial value problems of nuclear signal forming circuit. Iterative solution and the number of iterations are affected by iteration accuracy.ConclusionsThe error between the iterative method and the analytic solution is small. The higher the set data sampling rate is, the smaller the error is. The accuracy of iterative solution is adjustable, and almost the same effect as the recursive solution.is achieved.关键词：Nuclear signal;Iteration method;R-C integral circuit;C-R differential circuit;S-K low-pass filter circuit
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发布时间：2024-10-25
NUCLEAR ELECTRONICS AND INSTRUMENTATION
- “在铀浓缩离心级联卸料系统研究中，专家分析了阀门泄漏对分离功率的影响，为核安全监管提供参考。”摘要：BackgroundIn the process of uranium enrichment, the separation power is the key evaluation index, but the leakage of the valve will affect it.PurposeThis study aims to analyze the normal and abnormal conditions of uranium enrichment centrifugal cascade unloading system, and put forward the corresponding measures and suggestions of valve leakage for uranium enrichment industry and nuclear and radiation safety supervision department.MethodsThe cascade simulation method was used to analyze the influence of valve leakage by computer programming iteration. Emphasis was placed on the separation power change of centrifugal cascade unloading system for uranium enrichment.ResultsThe results show that it is difficult to judge the leakage of valve channels in the centrifugal cascade unloading system of enriched uranium by the process operation parameters. The influence of the process on the separation power of uranium enrichment varies with the leakage position of the valve channel, which has a great impact on the economy and safety of uranium enrichment. When the leakage rate is true, the separation power of uranium enrichment will change, and material loss of 0.1% will lead to a separation power loss of 3.8%.ConclusionsTherefore, it is necessary to judge the leakage point of the valve channel of the unloading system timely and accurately.关键词：Unloading system;Valve channel;Cascade simulation calculation
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发布时间：2024-10-25 -
Investigation of SASE FEL pulse in tender X-ray range reflection from Cr/B4C multilayer structures AI导读
“在X射线自由电子激光光束线领域，Cr/B4C多层膜结构优化设计取得新进展，为中能X射线反射性能研究提供新思路。”摘要：BackgroundReflective optics are essential elements for the beamline development of an X-ray Free Electron Laser (FEL) facility. Multilayer structures (MS), especially Cr/B4C MS, offer superior reflective properties in the tender X-ray range.PurposeThis study aims to investigate the reflection of SASE FEL pulses on Cr/B4C multilayer structures in the tender X-ray regime, and the pulse transport fidelity during the reflection.MethodsThe Cr/B4C multilayer structures were designed and optimized in the tender X-ray range. The data of SASE pulses used in the simulation were imported from GENESIS software, while both Parratt's rigorous iterative algorithm and Fourier analysis were carried out to investigate the reflection of Cr/B4C MS. Especially, a 0.2 nm thick inter-diffusion structure in-between Cr and B4C layers was considered to make the simulation more realistically.ResultsSimulation results show that the optimized MS can not only provide high reflectivity for the tender X-ray but also preserve the incident ultrafast SASE pulses in both time and frequency domains pretty well.ConclusionsThe excellent reflective performance for FEL pulses in the tender X-ray range could be delivered by realistic Cr/B4C MS containing inter-diffusion structures, proposed in this study.关键词：Multilayer structures;Self-amplified spontaneous emission;Free electron laser;Tender X-rays- 364
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发布时间：2024-10-25
NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH
- “重水慢化熔盐堆堆芯设计优化，降低出口温差，提高中子经济性，为堆芯设计提供参考。”摘要：BackgroundHeavy water moderated molten salt reactor (HWMSR) adopts heavy water as moderator and heavy metal elements dissolved in fluoride salt as the fuel, which has high neutron economy. But large temperature difference of fuel salt outlet will lead to the thermal fatigue of piping components at the top of the core.PurposeThis paper aims to optimize the core design of HWMSR to minimize the fuel salt outlet temperature.MethodsBy using the developed codes of neutron-thermal hydraulic coupling calculation and core critical search calculation, the power density distribution, outlet temperature distribution, initial 233U loading and breading ratio (BR) were analyzed for the cores with different size of molten salt channels.ResultsThe calculation results demonstrate that increasing the radius of molten salt channels in the inner core zone (correspondingly decreasing the radius of molten salt channels in the outer core zone) will decrease the peak of power density and the maximum outlet temperature of molten salt while the influence on BR and 233U initial loading.ConclusionsThis study provides a valuable foundation for core optimization of HWMSR.关键词：HWMSR;Thermal hydraulic;Neutronics;Thorium-uranium fuel cycle
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发布时间：2024-10-25 - “在核能辐射屏蔽领域，研究人员开发出耐高温中子屏蔽复合材料，具有优异的耐热性能，有望实现工程应用。”摘要：BackgroundHigh temperature neutron shielding of the reactor cavity in the third generation nuclear power plant requires a high temperature resistant shielding material, but there is no suitable material that meets the design requirements in the market.PurposeThis study aims to develop a high temperature resistant neutron shielding material for the needs of nuclear engineering, and investigate its heat resistance.MethodsFirst of all, high temperature resistant phenyl silicone resin and phenyl hydrogen silicone oil were used as matrix materials, and boron carbide powder was taken as neutron absorber. A high temperature neutron shielding composite was prepared by the matrix materials and boron carbide powder. Then, the heat resistance of the composite and the effect of different phenyl content were investigated in details. The thermal weight loss and off-gases mechanisms of the neutron shielding material were studied by thermogravimetric analysis combined with gas chromatography and mass spectrometry (TGA-GCMS) method. The long-term thermal aging behavior of the materials was explored by thermal aging oven, and the outgassing environment of the material was measured at ~500 ℃.ResultsThermo gravimetric analysis (TGA) results show that the thermal weight loss of the composite decreased gradually with the increase of phenyl content, and the 5% weight lost decomposition point is at the high temperature of 487 ℃. After 500 h thermal aging at 300 ℃, the total weight loss of the composite is less than 10%.ConclusionThe shielding material prepared and tested in this study has good thermal resistance and stability. It provides a kind of neutron shielding material with excellent heat resistance for nuclear energy and other radiation shielding fields, and is expected to be further applied in engineering.关键词：Neutron shielding material;High temperature resistance;Reactor cavity;Phenyl silicone resin
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发布时间：2024-10-25 - “在中性束注入系统领域，射频离子源驱动器等效阻抗计算模型的建立，为阻抗匹配网络设计提供参考。”摘要：BackgroundThe ion source is one of the key components of the neutral beam injection system. Radio frequency (RF) ion source has the advantages of long life time, easy maintenance and long pules operation, which make it the main alternative source for the neutral beam ion source in the future.PurposeThis study aims to analyze equivalent impedance characteristics of a high power RF ion source driver with emphasis on the impedance matching network and effective tuning of matching network to achieve high-power and stable plasma discharge.MethodsFirst of all, the analytical model was established on the basis of transformer model. The plasma conductivity was obtained by estimating the ohmic heating frequency and stochastic heating frequency in the plasma. Then, the equivalent impedance of the plasma was coupled to the excitation coils with the transformer model, and the equivalent impedance of the driver was obtained. Finally, parameters of the single drive RF ion source of negative ion based neutral beam injection (NNBI) system of Comprehensive Research Facility For Fusion Technology (CRAFT) were taken as example to calculate variation of equivalent impedance of actuator with plasma electron density by MATLAB code.Results & ConclusionsComputation results show that the analytical model proposed in this study can be used to quickly and accurately calculate the electron temperature in the driver under different gas pressures, and the equivalent impedance under different gas pressures and electron densities, which provides a reference for the reasonable design and tuning of impedance matching network.关键词：Neutral beam injection system;Inductively coupled plasma;Transformer model;Radio frequency ion source equivalent model
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发布时间：2024-10-25
NUCLEAR ENERGY SCIENCE AND ENGINEERING
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