分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： As a potential matrix of three-dimensional gel dosimeter, agarose hydrogels will be used for measuring radiation doses, hence the importance of studying their radiation resistance and radiolysis mechanism. Physical property and chemical structure of physically cross-linked agarose hydrogel samples irradiated to 0200 kGy by 60Co -rays were analyzed by universal testing machine, gel permeation chromatography, fourier transform infrared spectrometer, ultraviolet visible spectroscopy, nuclear magnetic resonance, and gas chromatography. The results showed that agarose hydrogels had good radiation stability below 25 kGy, and the maximum compression strength of sample was ca. 0.1 MPa at 25 kGy. The irradiated samples degraded obviously and liquefied gradually with increasing doses. Compared with unirradiated sample, carbonyl groups, which generated from the molecular chains of agarose hydrogels, were observed at 25 kGy and increased gradually with dose. The main gas products evolved from irradiated agarose hydrogels were H2, CO2, CO and CH4. Based on the analysis of radiolytic products, the radiolysis mechanism of agarose hydrogels under -radiation was proposed.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： High brightness -rays produced by laser Compton scattering (LCS) are ideal probes for the study of nucleon and nuclear structure. We propose such a -ray source using the backscattering of a laser from the bright electron beam produced by the linac of the Shanghai Soft X-ray Free-electron Laser (SXFEL) test facility at the Shanghai Institute of Applied Physics (SINAP). The performance is optimized through theoretical analysis and benchmarked with 4D Monte-Carlo simulations. The peak brightness of the source is expected to be larger than 21022 photons/(mm2 mrad2 s 0.1%BW) and photon energy ranges from 3.7 MeV to 38.9 MeV. Its performance, compared to Extreme Light Infrastructure-Nuclear Physics (ELI-NP), and the Shanghai Laser-Electron Gamma-ray Source (SLEGS), is given. The potential for basic and applied research is also briefly outlined.
分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： The hadron-quark phase transition is studied with the newly constructed HadronPoyakov-Nambu Jona-Lasinio (PNJL) model. Particularly, in the description of quark matter, we include the isoscalar-vector interaction. With the constraints of neutron star observations, our calculation shows the isoscalar-vector interaction between quarks is indispensable if massive hybrids star exist in the universe. Its strength determines the onset density of quark matter, and the mass-radius relations of hybrid stars. Also, as a connection with heavy-ion-collision experiments, we discuss the strength of isoscalar-vector interaction and its effect on the signals of hadron-quark phase transition in heavy-ion collisions, such as NICA at JINR-Dubna and FAIR at GSI-Darmstadt.
分类： 地球科学 >> 地理学 提交时间： 2021-11-10 合作期刊: 《干旱区科学》
摘要： Nitrogen (N) and phosphorus (P) are two essential nutrients that determine plant growth and many nutrient cycling processes. Increasing N and P deposition is an important driver of ecosystem changes. However, in contrast to numerous studies about the impacts of nutrient addition on forests and temperate grasslands, how plant foliar stoichiometry and nutrient resorption respond to N and P addition in alpine grasslands is poorly understood. Therefore, we conducted an N and P addition experiment (involving control, N addition, P addition, and N+P addition) in an alpine grassland on Kunlun Mountains (Xinjiang Uygur Autonomous Region, China) in 2016 and 2017 to investigate the changes in leaf nutrient concentrations (i.e., leaf N, Leaf P, and leaf N:P ratio) and nutrient resorption efficiency of Seriphidium rhodanthum and Stipa capillata, which are dominant species in this grassland. Results showed that N addition has significant effects on soil inorganic N (NO3–-N and NH4+-N) and leaf N of both species in the study periods. Compared with green leaves, leaf nutrient concentrations and nutrient resorption efficiency in senesced leaves of S. rhodanthum was more sensitive to N addition, whereas N addition influenced leaf N and leaf N:P ratio in green and senesced leaves of S. capillata. N addition did not influence N resorption efficiency of the two species. P addition and N+P addition significantly improved leaf P and had a negative effect on P resorption efficiency of the two species in the study period. These influences on plants can be explained by increasing P availability. The present results illustrated that the two species are more sensitive to P addition than N addition, which implies that P is the major limiting factor in the studied alpine grassland ecosystem. In addition, an interactive effect of N+P addition was only discernable with respect to soil availability, but did not affect plants. Therefore, exploring how nutrient characteristics and resorption response to N and P addition in the alpine grassland is important to understand nutrient use strategy of plants in terrestrial ecosystems.
分类： 化学 >> 物理化学 提交时间： 2017-11-05 合作期刊: 《结构化学》
摘要： Two new complexes [Ag(bix)]n·nNAA·nH2O (1) and [Cd(NAA)(phen)2(H2O)]2·2CH3COO-·H2O (2) (bix = 1,4-bis(imidazol-1-ylmethyl)benzene, HNAA = α-naphthylacetic acid, phen = 1,10-phenanthroline) have been successfully synthesized under hydrothermal conditions. Their structures have been determined by elemental analyses, IR spectroscopy, TG and single-crystal X-ray diffraction analysis. The intermolecular hydrogen bonding or π-π stacking interactions extend the complexes into a 3D supramolecular structure. Moreover, the luminescent properties of complex 2 have been investigated in the solid state.
分类： 化学 >> 物理化学 提交时间： 2017-11-05 合作期刊: 《结构化学》
摘要： A new complex [Zn(4-nph)(bib)]2n·nH2O (1) has been obtained by the reaction of metal (Zn(II)), 1,4-bis(imidazol-1-yl)-butane (bib) with 4-nitrophthalic acid (4-H2nph). The crystal structure of 1 has been determined by single-crystal X-ray diffraction analysis. Compound 1 is of triclinic system, space group P with a = 10.3251, b = 12.4503, c = 16.6497 Å, α = 88.487(3), β = 72.529(3), γ = 79.991(3)°, V = 2009.8(5) Å3 and Mr = 945.47. Complex 1 shows a three-dimensional (3D) framework. Moreover, through intermolecular hydrogen bonds, compound 1 is assembled into a supramolecular structure. The thermal stability and luminescent properties of 1 are also investigated.
分类： 动力与电气工程 >> 工程热物理学 提交时间： 2017-03-31 合作期刊: 《热科学学报》
摘要： Turbulent penetration can occur when hot and cold fluids mix in a horizontal T-junction pipe at nuclear plants. Caused by the unstable turbulent penetration, temperature fluctuations with large amplitude and high frequency can lead to time-varying wall thermal stress and even thermal fatigue on the inner wall. Numerous cases, however, exist where inner wall temperatures cannot be measured and only outer wall temperature measurements are feasi- ble. Therefore, it is one of the popular research areas in nuclear science and engineering to estimate temperature fluctuations on the inner wall from measurements of outer wall temperatures without damaging the structure of the pipe. In this study, both the one-dimensional (1D) and the two-dimensional (2D) inverse heat conduction problem (IHCP) were solved to estimate the temperature fluctuations on the inner wall. First, numerical models of both the 1D and the 2D direct heat conduction problem (DHCP) were structured in MATLAB, based on the finite difference method with an implicit scheme. Second, both the 1D IHCP and the 2D IHCP were solved by the steepest descent method (SDM), and the DHCP results of temperatures on the outer wall were used to estimate the temperature fluctuations on the inner wall. Third, we compared the temperature fluctuations on the inner wall estimated by the 1D IHCP with those estimated by the 2D IHCP in four cases: (1) when the maximum disturbance of temperature of fluid inside the pipe was 3癈, (2) when the maximum disturbance of temperature of fluid inside the pipe was 30癈, (3) when the maximum disturbance of temperature of fluid inside the pipe was 160癈, and (4) when the fluid temperatures inside the pipe were random from 50癈 to 210癈.
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