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Significance of Heavy-Ion Beam Irradiation-Induced Avermectin B1a Production by Engineered Streptomyces avermitilis
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Heavy-ion irradiation technology has advantages over traditional methods of mutagenesis. Heavy-ion irradiation improves the mutation rate, broadens the mutation spectrum, and shortens the breeding cycle. However, few data are currently available regarding its effect on Streptomyces avermitilis morphology and productivity. In this study, the influence of heavy-ion irradiation on S. avermitilis when cultivated in approximately 10 L stirred-tank bioreactors was investigated. The specific productivity of the avermectin (AVM) B1a-producing mutant S. avermitilis 147-G58 increased notably, from 3885 to 5446 mu g/mL, approximately 1.6-fold, compared to the original strain. The mycelial morphology of the mutant fermentation processes was microscopically examined. Additionally, protein and metabolite identification was performed by using SDS-PAGE, 2-and 3-dimensional electrophoresis (2DE and 3DE). The results showed that negative regulation gene deletion of mutants led to metabolic process upregulating expression of protein and improving the productivity of an avermectin B1a. The results showed that the heavy-ion beam irradiation dose that corresponded to optimal production was well over the standard dose, at approximately 80Gy at 220 AMeV (depending on the strain). This study provides reliable data and a feasible method for increasing AVM productivity in industrial processes.</span
A high-throughput screening method for breeding Aspergillus niger with C-12(6+) ion beam-improved cellulase
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">In this study, a high-throughput screening method was established through the 24-square deep-well microliter plate (MTP) fermentation and micro-plate detection for large-scale screening of the mutants. It was suitable for screening a large number of mutants and improving the breeding efficiency after heavy-ion beam irradiation. Seventeen strains showed higher cellulase activity compared with the initial strain after the screening of plate and MTP fermentation. The filter paper activity and beta-glucosidase activity of Aspergillus niger H11201 had increased 38.74 and 63.23 % separately compared with A. niger H11 by shaking flask fermentation, and it was genetically stable after being passaged to nine generations. The results indicate that the high-throughput screening method can be used for the quick breeding of A. niger with high cellulase activity.</span
beta-decay study of the T-z =-2 proton-rich nucleus Mg-20
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The beta decay of the drip-line nucleus Mg-20 gives important information on key astrophysical resonances in 20Na, which are relevant to the onset of the rapid proton capture process. A detailed beta-decay spectroscopic study of 20Mg was performed by a continuous-implantation method. A detection system was specially developed for charged-particle decay studies, giving improved spectroscopic information including the delayed proton energies, the half-life of 20Mg, the excitation energies, the branching ratios, and the log ft values for the states in Na-20 populated in the beta decay of Mg-20. A new proton branch was observed and the corresponding excited state in 20Na was proposed. The large isospin asymmetry for the mirror decays of Mg-20 and O-20 was also well reproduced. To resolve the long-standing problem about the astrophysically interesting 2645 keVresonance in Na-20 convincingly, a higher-statistics measurement may still be needed.</span
Observation of beta-delayed two-proton emission in the decay of Si-22
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The decay of the lightest nucleus with Tz=-3, Si-22, was studied by a silicon array. A charged-particle group at 5600 (70) keV in the decay-energy spectrum was identified experimentally as beta-delayed twoproton emission from the isobaric analog state (IAS) of Al-22. Experimental results of the IAS fed by a superallowed Fermi transition were compared with our large-scale shell-model calculations. The groundstate mass of Si-22 was obtained indirectly in the experiment for the first time. Two-proton separation energy for Si-22 is deduced to be -108(125) keV, which indicates that it is a very marginal candidate for two-proton ground-state emission. (C) 2017 The Authors. Published by Elsevier B.V.</span
兰州重离子加速器研究装置HIRFL
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">兰州重离子加速器装置HIRFL是目前我国规模最大、加速离子种类最多、能量最高的重离子研究装置, 主要技术指标达到国际先进水平, 是世界上几个重要的核物理研究设施之一. HIRFL由ECR离子源、扇聚焦回旋加速器SFC、分离扇回旋加速器SSC、放射性束流分离线RIBLL1和RIBLL2、冷却储存环主环CSRm和实验环CSRe等主要设施组成. HIRFL具有加速全离子的能力, 可提供多种类、宽能量范围、高品质的稳定核束和放射性核束, 用以开展重离子物理及交叉学科研究. 本文重点介绍了兰州重离子加速器装置HIRFL的发展现状以及取得的系列成果, 同时对国内外重离子加速器装置的发展现状做了简要介绍.</span><span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Heavy ions accelerator has greatly scientific significance in nuclear physics, atomic physics and astrophysics. It is also of great social needs in many application fields, such as nuclear detection, radiation medicine and medical physics. In addition, Heavy ions accelerator has important application prospects in the interdisciplinary fields of nuclear physics,nuclear technology, radiation biology, material science, biology and agriculture. Therefore, heavy ions accelerator makes great contributions to the promotion of human development and social progress. At present, there are more than 30 large scale heavy ions accelerators. And the main overseas heavy ions accelerators are the BNL-RHIC in the United States, the RIKEN-RIBF in Japan, the MSU-FRIB in the United States, the GANIL-SPIRAL2 in France and the FAIR in Europe which is under construction. In China, however, there are the BRIF in Beijing and the HIRFL in Lanzhou being operation and High Intensity heavy-ion Accelerator Facility (HIAF) which will be built in Huizhou. Heavy Ions Research Facility in Lanzhou (HIRFL), one of the most important research facilities for nuclear physics in the world, is the largest scale heavy-ion accelerator facility with the most ion species and the highest ion energy in China at present. And its main parameters have reached international advanced level. HIRFL is composed of ECR ion source, sector focused cyclotron (SFC), separated sector cyclotron (SSC), radioactive ion beam lines RIBLL1 and RIBLL2, cooler storage rings CSRm and CSRe, and many terminals. HIRFL can accelerate all ion species and provide high quality stable beams and radioactive beams with many ion species and broad energy ranges to carry on the heavy-ion physics and crossing discipline research. This paper is mainly to present the status of HIRFL and its progress, and the development of heavy-ion accelerator facilities at home and abroad are also introduces briefly.</span
New development of laser ion source for highly charged ion beam production at Institute of Modern Physics
No full textK-shell X-ray production in Silicon (Z(2)=14) by (1 <= Z(1) <= 53) slow ions
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">K-shell X-ray emission of Silicon induced by near-Bohr-velocity ions was systematically investigated in collision systems for which the ratio of projectile-to-target atomic numbers (Z(1)/Z(2)) ranged from 0.07 to 3.79. The results show that, in asymmetric collisions, the measured K-shell X-ray production cross sections of Silicon fit very well with the predictions of different direct ionization models depending on the atomic number of projectile. In the case of near-symmetric collisions (Z(1)/Z(2) similar to 1), an obvious enhancement of the X-ray production cross section was observed, which can be attributed to the vacancy transfer within the framework of quasi-molecular model. (C) 2016 Elsevier B.V. All rights reserved.</span
Longitudinal electron cooling experiments at HIRFL-CSRe
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">At the heavy ion storage ring HIRFL-CSRe an electron cooler is operated to improve the beam conditions for experiments. The properties of cooled beams have been studied. The longitudinal beam dynamics during the cooling process was measured by a resonant Schottky detector. The dependencies of the parameters electron beam density and profile on cooling times were investigated. The friction force was measured directly with the aid of the high voltage system of the cooler and with the application of the beam bunching system as well. An experiment with bunched cold beam showed a dependence of the bunch length on the beam density. (C) 2015 Elsevier B.V. All rights reserved.</span
重离子储存环CSRe上激光冷却相对论能量类锂 ~(12)C~(3+)离子束的实验研究进展
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">激光冷却储存环中相对论能量的重离子束是最有希望得到高相空间密度离子束、实现离子束相变并且获得有序束和晶化束的一种方法. 相对于已经比较成熟的随机冷却和电子冷却技术, 储存环上重离子束的激光冷却具有冷却速度快, 冷却作用力强的特点, 可以将离子束冷却到极低温度(mK), 在激光冷却的同时还可以开展高电荷态离子的精细激光谱学实验. 本文介绍了中国科学院近代物理研究所大科学装置重离子冷却储存环CSRe上开展激光冷却重离子束的实验原理和实验方法, 给出了在CSRe上首次激光冷却能量为122 MeV/u的类锂~(12)C~(3+)离子束测试性实验结果, 并且展望了在未来大型加速器HIAF上开展类锂类钠高电荷态离子的激光冷却和精细激光谱学实验.</span><span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Laser cooling of relativistic heavy ion beams at storage rings is one of the most promising techniques to reach high phase-space densities and achieve phase transition, ordered beam even crystalline beam. Compared with the established cooling schemes at storage rings, such as stochastic cooling and electron cooling, laser cooling has many advantages such as fast-cooling, ultra-strong cooling force and providing an ultra-low temperature (mK) ion beams. In addition, the precision laser spectroscopy of the highly charged ions can be performed by using the laser-cooled ion beams during the laser cooling experiments. We introduce the experimental principal and methods of laser cooling of relativistic ion beams at the experimental cooler storage ring of the CSRe at the Institute of Modern Phyics, Chinese Academy of Sciences. The first experimental results from a beam time aiming for laser cooling of 122 MeV/u Li-like ~(12)C~(3+) at the CSRe with a pulsed laser are presented, and laser cooling and precision laser spectroscopy of relativistic Li-like and Na-like highly charged ions at the future large facility HIAF and FAIR are outlined.</span
Advancement of highly charged ion beam production by superconducting ECR ion source SECRAL
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">At Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS), the superconducting Electron Cyclotron Resonance (ECR) ion source SECRAL (Superconducting ECR ion source with Advanced design in Lanzhou) has been put into operation for about 10 years now. It has been the main working horse to deliver intense highly charged heavy ion beams for the accelerators. Since its first plasma at 18 GHz, R&D work towards more intense highly charged ion beam production as well as the beam quality investigation has never been stopped. When SECRAL was upgraded to its typical operation frequency 24 GHz, it had already showed its promising capacity of very intense highly charged ion beam production. And it has also provided the strong experimental support for the so called scaling laws of microwave frequency effect. However, compared to the microwave power heating efficiency at 18 GHz, 24 GHz microwave heating does not show the 2 scale at the same power level, which indicates that microwave power coupling at gyrotron frequency needs better understanding. In this paper, after a review of the operation status of SECRAL with regard to the beam availability and stability, the recent study of the extracted ion beam transverse coupling issues will be discussed, and the test results of the both TE01 and HE11 modes will be presented. A general comparison of the performance working with the two injection modes will be given, and a preliminary analysis will be introduced. The latest results of the production of very intense highly charged ion beams, such as 1.42 emA Ar12+, 0.92 emA Xe27+, and so on, will be presented. (C) 2015 AIP Publishing LLC</span