Subjects: Physics >> Nuclear Physics submitted time 2024-02-06
Abstract: Recently, an inelastic scattering experiment of 16O + 12C was performed at the Beijing Tandem Accelerator Nuclear Physics National of China Institute of Atomic Energy. New evidence for the existence of Bose-Einstein condensation state of 16𝑂 has been obtained. Employing a series of double-sided-silicon-strip-based telescopes, this experiment achieved accurate particle identification and coincidence measurement of 4-𝛼 in the decay of 16O for the first time. Based on this, high-resolution reaction 𝑄-value spectra was obtained and clear 4-𝛼 resonance states were reconstructed. In the vicinity of the 4-𝛼 separation threshold, 4 highly significant (3 of them above 5𝜎) resonance states were observed, which decay to the characteristic pattern of 12C(Hoyle state) + 𝛼, consistent with the predicted Hoyle-BEC structure and its rotating band features. The observation results will promote further theoretical research, and more measurements are needed for these resonance states in experiments.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-04
Abstract: The nuclear reaction at energies near the Coulomb barrier is an effective way to study the interaction between nuclear structure and dynamics. As more exotic weakly bound nuclei become accessible at new accelerator facilities, it is becoming critically important to understand the influence of weak binding energy on reaction dynamics, including on fusion. At present, a large number of experiments have shown that the complete fusion cross section between stable weakly bound nuclei such as 6,7Li, 9Be and heavy mass target nuclei is suppressed about 30% lower than the fusion cross section calculated by existing theoretical models and the fusion cross section derived from tightly bound nuclear systems. In order to investigate the breakup effect of weakly bound nuclei on the suppression of the complete fusion cross section, studying the breakup reaction and mechanism of weakly bound nuclei has become concerned. This article introduces the recent work on breakup of weakly bound nuclei, including the research of our group.
Subjects: Physics >> Nuclear Physics submitted time 2023-09-04 Cooperative journals: 《核技术》
Abstract: Through the use of the accelerator facilities at home and abroad, the nuclear reaction group of the China Institute of Atomic Energy has made many remarkable achievements in the study of fusion-fission dynamics, fusion-enhancement mechanisms at sub-barrier energies, reaction dynamics induced by exotic nuclei, and the related exotic nuclear structure and proton decay. In this study, some representative achievements are reviewed briefly. (1) The fusion mechanisms at near-barrier energies were investigated systematically, and a self-consistent method to evaluate the coupled-channel effects was proposed. (2) Nuclear deformation parameters were extracted from backward quasi-elastic scattering, which offered evidence for hexadecapole shapes. (3) A surrogate capture method was developed, based on which the first 239Pu(n,2n) excitation function developed in China was derived. (4) Systematic studies of exotic decay spectroscopies for proton-rich nuclei in the sd-shell were performed, following which a β2p decay of 22Si and a large isospin-asymmetry decay were discovered, and a strongly isospin-mixed doublet in 26Si was revealed. (5) Systematic studies of reaction mechanisms induced by exotic nuclei at energies close to the Coulomb barrier were performed, providing evidence for the failure of the dispersion relation in the optical potential of 6He+209Bi, and the reaction dynamics of proton drip-line nuclei of 8B and 17F were investigated. Future research based on the new HiTOF and BRIF facilities is discussed as well.
Subjects: Astronomy submitted time 2023-07-14 Cooperative journals: 《天文学报》
Abstract: Ion cyclotron waves (ICWs) are one kind of plasma waves whose frequency is close to the ion cyclotron frequency. They exist widely in the upstream of Mars, and the frequency observed by satellites is generally near the proton cyclotron frequency. ICWs are byproducts in the production processes of pick-up ions. The occurrence of ICWs constitutes, in principle, an indirect signature of the presence of newborn planetary protons. ICWs upstream of Mars have received much attention since they were first reported in 1990. In this review, we summarize the research progress of ICWs in the upstream of Mars, including the observation of ICWs, the wave generation mechanism, their statistical properties and related future research trends.
Subjects: Astronomy submitted time 2023-07-14 Cooperative journals: 《天文学报》
Abstract: Electromagnetic Ion Cyclotron (EMIC) waves in the solar wind have received much attention since they were discovered. EMIC waves are important in the plasma heating and acceleration in the solar wind because they can effectively transfer wave energy to ions via the cyclotron resonance. This paper summarizes the progress of EMIC waves observation and theoretical research in the solar wind, including a series of results obtained from EMIC waves observation in and out of magnetic clouds, Interplanetary Coronal Mass Ejections (ICMEs) sheath region, and the research progress for excitation mechanism of EMIC waves based on observations. Finally, the potential research of EMIC waves in the solar wind in the future is anticipated.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract: The ocean is essential to country’s strategic interests and common destiny of mankind, and therefore equipment of various kinds is urgently needed for all-around and multi-dimensional ocean observation and exploration. This article brief introduced the two technological approaches of nuclear energy supply for underwater observation and exploration equipment and relevant exchange technologies of nuclear heat to electric power, quantitatively summarized the applicability of nuclear energy supply on all kinds of equipment, discussed the nuclear safety issues thereon, and then recommended that the technology research of radioisotope fabrication and separation and the construction of relevant facility, the development of individual reactor and the construction of relevant common facility, the technology research of thermoelectric conversion, and the research of relevant nuclear safety issues, should be special supported.
Subjects: Astronomy >> Astrophysical processes submitted time 2020-09-23 Cooperative journals: 《天文研究与技术》
Abstract: II型多功能天文经纬仪是中国科学院云南天文台为了满足利用多台仪器组网监测测站本地铅垂线变化信息的需求所研制的一种地面天体测量仪器。在该仪器的图像采集系统中,使用了三台非制冷CCD作为采集终端,工作在外触发模式,利用望远镜控制系统提供的外触发信号按照观测时序触发相机采集。介绍了望远镜的具体工作模式,对图像采集系统的工作流程给予了说明;介绍了采集系统的硬件构成、软件框架和所涉及的主要编程方法。给出了图像采集系统的软件工作界面和所采集的图像,并对所拍摄恒星像成像质量进行了简单分析。
Subjects: Astronomy >> Astrophysical processes submitted time 2020-07-21 Cooperative journals: 《天文研究与技术》
Abstract: 自动气象监测系统是现代天文观测台站必备的辅助系统之一,传统自动气象系统是基于微控制器或PC开发的。微控制器多用于工业控制,无法满足多任务和批量数据的快速处理;PC由于高功耗、高成本及低可移动性无法在野外如选择台址时使用。为了克服上述两种开发方式的缺点,本文采用基于ARM架构的嵌入式系统为抚仙湖NVST开发一套低功耗、低成本、高稳定性的自动气象监测系统。本文介绍了NVST气象站的整体设计,软硬件功能以及调试中遇到的问题及解决方法。
Subjects: Civil Engineering and Building Construction >> Civil Construction Engineering submitted time 2018-07-18 Cooperative journals: 《土木建筑工程信息技术》
Abstract: The subway station is buried deep underground, and its structure is complex and special. If a fire breaks out, it will cause heavy casualties and property losses. How to effectively prevent and reduce the casualties in the case of fire, especially to prevent the occurrence of major accidents such as group death, has become a hot spot and focus of the research in the field of fire control safety in the world. In order to take timely and effective measures in station fire accidents, reduce the range of the impact of the fire accident to the minimum and the loss to the lowest, this paper analyzes and classifications the fire warning system and related early warning mechanism of the subway station fire. Different fire occurrence locations in the railway station are analyzed and discussed. It is of great significance to research the fire safety of large subway stations, and it also provides a reference for the design and management of subway stations.
Subjects: Astronomy >> Astrophysical processes submitted time 2018-05-28 Cooperative journals: 《天文研究与技术》
Abstract: 太阳图像中包含了各种不同尺度、不同结构以及不同亮度的活动现象,它们都是实测太阳物理的研究目标。这些活动现象经常会使图像显示的跨度过大,导致图像暗弱细节结构被隐藏。对于地基望远镜,由于地球大气对观测数据的影响,也造成图像整体对比度下降。这些都不利于人们直观地从图像中发现感兴趣的太阳活动现象或结构特征。针对这些问题,运用直方图规定化的方法对实测太阳物理中常遇到的几类观测目标图像(太阳极紫外像,太阳光球黑子像,色球活动区像以及色球日珥像)进行处理,通过瑞利分布、双高斯分布以及三重瑞利混合分布等直方图形式实现对这几类图像的显示对比度增强。通过对空间望远镜SDO的极紫外太阳像和1m新真空太阳望远镜(New Vacuum Solar Telescope, NVST)的色球和光球像的处理展示了该方法的处理效果。结果表明,方法可以有效提高各类太阳活动现象的显示度,便于人们在研究初期发现感兴趣的活动现象。
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-07 Cooperative journals: 《南方医科大学学报》
Abstract: Objective To screen the genes related with leukocyte responses in mice early after burn injury by bioinformatic analysis of the gene expression profiling data. Methods Gene expression profiles were obtained from GEO (GSE7404, Mouse musculus, 25% TBSA, full-thickness) database. After screening of the differentially expressed genes (DEGs) through paired-sample t-test and fold-change, DAVID online tools were used to select the DEGs related to leukocyte responses to burns by GO functional enrichment analysis; the interacting genes identified through KEGG pathway enrichment analysis were transferred to STRING to construct the protein-protein interaction (PPI) network. Biological annotation of the sub-networks was executed using the software Cytoscape. Real-time PCR was used to verify the DEGs identified in mice. Results Of the 259 leukocyte response-related DEGs screened at 1 day post-burn, 118 were up-regulated and 141 were down-regulated. KEGG pathway enrichment analysis showed that the pathways were associated with the immune function, cell growth and cell death. PPI network and module analysis suggested that some of genes (such as Lck, Stat1, Myd88, Stat3, and Jun) play critical roles in the PPI network post-burn. RT-PCR results were consistent with those of bioinformatic analysis. Conclusion Lck, Stat1, Myd88, Stat3, and Jun might be critical players in the development of leukocyte response in mice early after burn injury. Our finding provides new insights into the pathogenesis of leukocyte response to burn injury and identifies several potential biomarkers for burn treatment.
Subjects: Materials Science >> Materials Science (General) submitted time 2017-11-21 Cooperative journals: 《金属学报》
Abstract:材料的成骨性能(即材料表面或周围促进新骨生成的性能)一直以来是大部分骨科植入性医疗器械的首要临床要求。近年来,材料的抗感染或者抗菌性能(尤其是不依赖抗生素的抗感染或者抗菌性能)逐渐成为骨科植入物的另一重要临床要求。因此,开发同时具有成骨和抗感染能力的生物材料对于骨科临床具有重要意义。医用金属材料在骨科植入物中占有重要地位,但兼具这两种性能的金属材料在以往的临床实践或基础研究中都极为少见,最近才得以广泛研究。本综述将介绍同时具有成骨和抗感染性能的新型医用金属材料的研究进展,首先介绍相关金属材料以及金属材料表面改性的研究成果,然后对材料兼具成骨和抗感染的机理进行分析讨论,最后提出此类新型医用金属材料的研究展望。
Subjects: Astronomy >> Astrophysical processes submitted time 2017-10-20 Cooperative journals: 《天文研究与技术》
Abstract:1 m太阳望远镜多通道高分辨成像系统是望远镜的重要终端设备之一,目前由H通道(线心656. 283 nm)和Ti0通道(705. 8 nm)构成。主要介绍了多通道高分辨观测系统软件的设计。观测系统在功能上主要实现了H通道多波长点扫描观测模式,Ti0通道多时间分辨率观测模式,以及为满足多通道发展的需求,如常规观测通道的增加以及探测器的更换等,在系统架构上采用了松藕合的分布式分层结构。