Search

MIS6 to MIS5 is a typical transition period from glacial to interglacial periods. The climate elements of MIS5 are similar to that of the current warm period, and studying its evolution process can better understand the climate change process of the current warm period and the future climate change trend. Based on modern spore–pollen and meteorological data, as well as stratigraphic spore–pollen and particle size indicators from the Yinchuan Basin in the monsoon margin area, the locally weighted average partial least squares method (LWWA-PLS) reconstruction results are considered to be the most robust after the selection of the training set, screening of the master climate parameters, cross-validation of the five reconstruction models, regional comparison, significance testing, and ecological interpretation. The climatic evolution from MIS6 to MIS5 can be divided into six stages. 157 to 131 ka, the climate was cold and humid, where wet and cold-loving arborvitae vegetation developed, with the average annual precipitation (Pann) being 424.99 mm and the average temperature in July (TJuly) 22.58 ℃. 131 to 119 ka, the climate turned wet and warm, and warm-loving trees and herbs developed; the Pann was 410.95 mm, and the TJuly was 23.62 ℃. 119 to 111 ka, the Pann was 369.50 mm, and the TJuly was 22.53 ℃; cold-loving herbs and trees developed in a cold and dry climate. 111 to 98 ka, the Pann is 378.39 mm, and the TJuly is 22.86 ℃; warm-loving trees account for a higher proportion in the early stage, and the number of cold-loving trees increased in the late stage; the climate was overall dry and warm, and the temperature increased first and then decreased. 98 to 85 ka, the Pann was 278.24, and the TJuly was 22.01 ℃; the overall climate was the driest and coldest, and cold-loving trees developed well. 85 to 78 ka, the Pann was 364.21 mm, and TJuly was 23.45 ℃; the climate turned warm and humid, and trees and herbs developed in this period. The reconstructed climate parameters' ensemble empirical mode decomposition (EEMD) results respond well to the 23 ka precessional cycle. Comparison with the mid- and high-latitude geologic record of the Northern Hemisphere suggests that solar radiation-influenced climatic variability in the North Atlantic primarily drives changes in the East Asian monsoon through the westerly wind circulation as well as the oceanic transport zone, which in turn influences climatic change in the Yinchuan Basin.

The electrocatalytic reduction of carbon dioxide into valued chemicals such as formic acid has the most promising potential in applying renewable energy for useful materials and mitigating the greenhouse effect. However, the studies still focus on developing catalysts with low price and high catalytic properties. In this study, nitrogen atoms were decorated into carbon structure by a unique ultrasonic method, then the nitrogen-doped carbon material was applied as catalyst in CO2 reduction, it exhibited excellent electrochemical activity, 4 times higher than the normal method. The improved activity should be attributed to the interaction between nitrogen and carbon atoms through analysis.

Microspheres are widely used as profile control and water plugging products at present. However, the current research on microspheres is mainly focused on oil displacement experiments. In order to solve this problem, based on the Bohai sea in the BZ of inhomogeneous reservoir conditions, this article has done the matching study on particle size and hole roar and the seepage research in porous medium by means of particle size analysis, pressure tests, single-phase block experiments, and the double tube parallel oil displacement experiments, revealing the characteristics of oil & water selective plugging and the mechanism of oil displacement in porous media. The results show that the average particle size of the microspheres increases from 4.857μm to 24.53μm, and the maximum expansion factor reaches 5.03 times after 72h of swelling in BZ25 oilfield water at 75 C. In the two-pipe parallel oil flooding experiment with the permeability of 1000mD and 3000mD respectively, the comprehensive recovery rate after the first water flooding is 28.06%, and the two-pipe average recovery rate is increased by 1.58% after the injection of 2000ppm microsphere with 0.3PV, and there is no significant increase in oil displacement efficiency. The comprehensive recovery rate reached 38.6% and increased by 8.99% after 4PV of subsequent water flooding, indicating that microsphere flooding effectively improved the water sweep efficiency of subsequent injection.

The electron beam radiation method is emitted by electronic accelerators, which can change the chemical physical properties of radiation. Silicone rubber samples after different irradiation intesities were carried out for the 1000h aging test, and the electronic scanning microscopy (SEM), mechanical tensile and hydrophhy angle of the silicone rubber sample were measured, the test results shows that: after 1000h aging test, the visual apperence of the sample did not changed, the SEM showed that the surface of the silicone rubber became rough and the porosity increased, and the mechanic tension decrease. For moderate Irradiation intensity(60KGy), the aging characteristics of silicon rubber can be improved.