Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Northeast China is a classic weakening area and becomes a difficult region of land development and high-quality development for the social-economic-ecological system. Its revitalization has the key supporting significance for the realization of the regional coordinated development in China. Based on the review on the evolution of the revitalization strategy of Northeast China and its experiences, this paper analyzes the current problems of Northeast China from the perspectives of the business environment, technological innovation, resources outflow, etc. And, the new situation and key relationship for the future revitalization of Northeast China are discussed. Then, we propose the whole thinking of revitalization development of Northeast China and design the strategical path from the perspectives of ecological protection, spatial development, and economic structure adjustment.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： This paper summarizes the characteristics of natural ecological conditions, the current situation of economic and social development, existing problems and development opportunities of the Yellow River Basin. The overall framework of the national strategy for ecological protection and high-quality development of the Yellow River Basin has been set up according to the three logical progressive links of basement-ecological priority, bearing capacity-development constraint, driving force-internal and external relevancy. It has formed the academic thinking of delimiting ecological, agricultural and urban functional areas through the evaluation of the suitability of human activities for land and space development, evaluating and calculating the resource and environment carrying capacity of the three functional areas, and then formulating high-quality development strategies for different functional areas according to the carrying capacity. The ecological restoration and protection strategies such as ecological migration urbanization construction project, agricultural planting structure adjustment, dry farming basic farmland construction, classification and batch solution to the historical problems of mined out areas of energy and mineral resources are put forward. The proposed high-quality development measures mainly include expanding the scale of renewable energy development, such as solar energy, wind energy and hydropower, developing characteristic bio-medicine and healthy food industries, developing new strategic industries such as electromechanical, electronic information and artificial intelligence with the help of “three lines” state-owned enterprises’ innovation potential, innovating the mechanism of industrialization transformation of scientific and technological achievements and the system of value distribution of resource advantages, improving the modern management system such as spatial fine governance, regional differential development, and opening up.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： “Double evaluation”, the abbreviation of the evaluation of resource and environmental carrying capacity and territorial development suitability, is the important basis and prerequisite for the implementation of spatial planning. This study systematically expounded the scientific concept, study framework, and research process of “double evaluation”, and discussed the core role in promoting the high-quality development of spatial development. This article firstly depicts the main development of “double evaluation” in MFOZ researches, including the proposal and improvement of the theoretical concept, the establishment of evaluation framework, and the application in MFOZ planning. Then, we analyze the main function of “double evaluation” and its irreplaceable fundamental role in optimizing spatial development pattern. As an effective means of cognizing land surface, “double evaluation” could provide the comprehensive and scientific understanding of regional background conditions as well as recognizing the prominent problems and major contradictions in spatial development. Based on it, the “double evaluation” would support basic materials for spatial planning compilation and guiding spatial planning implications by coupling various types of planning in different levels and supervising the implementation of planning. The limitations and proposals of the “double evaluation” are discussed to proper use it in actual work, which emphasizes that the adjustment of technical methods with local conditions and other basic work should also be taken into account. Meanwhile, we discussed the main features and problems of “Guidelines for the Evaluation of Resource and Environmental Carrying Capacity and Territorial Development Suitability (Trial)”, which was recently released by the Ministry of Natural Resources. Lastly, suggestions are made on the direction of improving and deepening the method and application of “double evaluation” in the optimization of spatial development pattern.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： With the development of hydrogen economy, the demand of structural materials with high strength suitable for service in hydrogen or hydrogen-bearing environments such as storage of hydrogen gas was incremental. An optional structural materials is J75 alloy, which is mainly strengthened by an ordered fcc g' phase, Ni3(Al, Ti), coherent with the austenite matrix. Investigation on J75 alloy indicated that the commercial alloy free of B would lose about half its ductility when charged with hydrogen, accompanied by a change of fracture mode from ductile rupture to brittle-appearing intergranular fracture. Otherwise, an improvement in ductility and hydrogen resistant performance was observed in the J75 alloy with trace B, however, its role in the alloy is unclear. So, in present work, mechanism of B in the J75 hydrogen-resistant alloy was investigated by means of OM, SEM, TEM, EPMA, 3DAP, SIMS, hydrogen penetration, thermal hydrogen charging experiments and tensile tests. It was found that a lot of Ti segregated at grain boundaries (GBs) in the alloy free of B, resulted in abundant precipitation of cellular h phases. However, the cellular h phase was not observed in the alloy with B, and it could be attributed to the segregation of B atoms at GBs and inhibited the segregation of Ti. A lower hydrogen diffusion coefficient was observed in the alloy with B than that in the alloy free of B by hydrogen permeation, indicating that diffusion velocity of H atoms in the alloy had been decreased by the addition of B. Moreover, segregation of B at GBs could not only inhibit the precipitation of h phases but also decrease the number of H atoms there, which would improve the hydrogen-resistant performance of the alloy.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： The chemical compositions of C and Mn have a strong influence on the stability of the metastable retained austenite at room temperature. In the intercritical annealing process, Mn element improves the stability of the austenite by partitioning from ferrite to austenite and the enrichment of Mn in austenite can also impact on the diffusion of C element from martensite to retained austenite in partitioning process. Based on C partitioning, Mn partitioning can further improve the product of strength and elongation, and has no negative effect on weldability of the low carbon high strength steel. Thus, it can effectively solve the contradiction between mechanical property and weldability of low carbon high strength steel in traditional quenching-partitioning (Q&P) process. In this case, it is of great significance to study the Mn pre-partitioning mechanism and its influence on C partitioning and retained austenite of the low carbon high strength steel. Therefore, one low alloy C-Si-Mn steel was studied in the present work. The Mn pre-partitioning behavior and its effect on C partitioning and the stability of the retained austenite were investigated by means of intercritical heating-quenching (IQ) process, Q&P and intercritical heatingaustenitizing-quenching-partitioning (I&Q&P) process. The results showed that during the process of phase transformation in the intercritical reheating, C and Mn elements constantly diffused from ferrite to austenite. When this process ended, C and Mn elements enriched in austenite. While Mn element in microstructure at room temperature was still enrichment and C element enriched regularly between the martensite laths in the I&Q&P treated steel. With the increase of C partitioning time in both Q&P and I&Q&P process, the tensile strength of steel was decreased constantly, while the elongation showed an increasing fristly and then decreasing trend. The product of strength and elongation of the steel treated by I&Q&P process reached 23478 MPa�% with the C partitioning time of 90 s. The more austenite in martensite phase would be obtained after the first quenching with the Mn pre-partitioning. It was important to prompt more C diffusing into austenite during C partitioning process to stabilize more retained austenite at room temperature of the steel after the second quenching. With the same experimental conditions, the retained austenite of the combined effects of C and Mn partitioning during I&Q&P process would be increased 2.4% than the effect of C partitioning during Q&P process.
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-07 Cooperative journals: 《南方医科大学学报》
Abstract： To access left ventricular global deformation abnormalities during low-dose dobutamine stress test (DSE) by three-dimensional speckle-tracking echocardiography (3D-STE)in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS), and explore the diagnostic value of 3D-STE combined with DES for NSTE-ACS. Methods Forty-nine patients with suspected NSTE-ACS underwent DSE and coronary angiography with an initial dobutamine dose of μg•kg-1min-1kg'，which was doubled at 3-min intervals to the peak dose of 20μg•kg-1min-1.The global longitudinal strain (GLS), global circumferential strain (GCS), territory longitudinal strain (TLS), and territory circumferential strain (TCS) of the left ventricular subendocardial myocardium were measured with 3D-STE at rest and at the peak-dose stage. Conventional echocardiography and 3D-STE parameters and their changes during DSE were evaluated, and their diagnostic values were analyzed according to the receiver-operating characteristic (ROC) curves. Results All the patients completed DSE uneventfully and 3D-STE showed a good reproducibility of the results. Compared with patients with non-NSTE-ACS, NSTE-ACS patients showed obviously reduced resting left ventricular global deformation function especially in terms of circumferential deformation (P<0.05); the ROC curves for the parameters were similar between the two groups (P>0.05). During DSE, the global deformation differences between the two groups further increased (P<0.01), and the diagnostic values of the peak-dose stage parameters were significantly greater than those of the resting parameters. ROC curves analysis showed that TLS and TCS at peak-dose stage had the highest diagnostic value for NSTE-ACS. Conclusion 3D-STE combined with low-dose DSE is a safe and effective noninvasive technique for accessing and identifying NSTE-ACS, and DSE can significantly enhance the diagnostic value of 3D-STE.
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