Summary of the Frontier Introduction of Preparation of Secondary Metabolites in Plant Cell Culture

Plant cell culture technology is a technology that applies the research results of cell engineering to produce plant biological products at the cellular level. In recent years, the secondary metabolites of plants have attracted more and more attention. The use of plant cell culture technology is a fast and efficient method of producing secondary metabolites

Age-related differences in the removal of information from working memory

Removal has been assumed to be a core mechanism in working memory. However, it remains unclear whether children can actively remove outdated information from working memory and how this ability develops as children age. The current study aims to examine age-related differences in removal ability and its relations with cognitive control and working memory capacity. Children aged 7, 9, and 11 years performed a modified working memory updating task assessing removal efficiency. In addition, a battery of cognitive control and working memory capacity tasks were administered. Results indicated that updating response times reduced considerably when a longer time was given for removal suggesting that children aged 7 to 11 years can actively remove outdated items from working memory prior to encoding the new ones, and that removal efficiency increased with age. More importantly, age-related increases in removal efficiency occurred concurrently with the development of working memory capacity. Proactive control predicted removal efficiency over and beyond age and working memory capacity. The findings shed new light on the mechanisms underlying the development of working memory updating

Experimental Study on Kaiser Effect of Reinforced Concrete Simply-Supported Beams

With the progress of transportation, an increasing number of bridges are put into operation, and the assessment of bridge bearing capacity is considered a significant measure to ensure bridge safety. As a critical approach for structural monitoring, acoustic emission is widely used in engineering projects. Since the Kaiser effect is an important phenomenon in acoustic emission, it is necessary to explore the Kaiser effect of reinforced concrete structures and the determination method of the Kaiser point. In this thesis, four reinforced concrete simply supported beams were utilized for the graded loading experiment under bending loads. After accumulating acoustic emission parameters, Kaiser point was selected for preliminary evaluation. Taking Kaiser point as the midpoint, the appropriate interval was determined. According to the continuity criterion of acoustic emission signals and the quadratic fitting curve based on experimental data, the Kaiser point was corrected by following the average growth rate of acoustic emission parameters. These simply supported beams were classified into two groups. One group was used to explore the acoustic emission characteristics when the load was less than the historical maximum, while the other group was used to analyze changes in the Kaiser effect with increasing load. Finally, based on the results of the specimen inspection, the influence of initial damage on the Kaiser effect was analyzed. The research results alleviated the influence of human factors on the determination of the Kaiser point and can serve as the theoretical basis for damage monitoring based on the Kaiser effect and bearing capacity evaluation of reinforced concrete structures

Topological dissipative Kerr soliton combs in a valley photonic crystal resonator

Topological phases have become an enabling role in exploiting new applications of nonlinear optics in recent years. Here we theoretically propose a valley photonic crystal resonator emulating topologically protected dissipative Kerr soliton combs. It is shown that topological resonator modes can be observed in the resonator. Moreover, we also simulate the dynamic evolution of the topological resonator with the injection of a continuous-wave pump laser. We find that the topological optical frequency combs evolve from Turing rolls to chaotic states, and eventually into single soliton states. More importantly, such dissipative Kerr soliton combs generated in the resonator are inborn topologically protected, showing robustness against sharp bends and structural disorders. Our design supporting topologically protected dissipative Kerr soliton combs could be implemented experimentally in on-chip nanofabricated photonic devices.Comment: 16 pages, 12 figure

Research progress and development tendency of polymer drilling fluid technology for unconventional gas drilling

Unconventional gas includes tight sandstone gas, shale gas, coalbed methane, and natural gas hydrate. With huge reserves, unconventional gas has become the most important natural gas resource successor after the end of the “Easy Oil era.” The drilling fluid is an indispensable wellbore working fluid for unconventional gas drilling with multiple functions. The polymer drilling fluid (PDF) is the most common, longest developed, and most diverse drilling fluid type. With advantages of easily controlled rheology, convenient on-site performance maintenance, and specifically low cost and weak environment pollution, the PDF is gradually replacing the oil-based drilling fluid as the first choice for unconventional gas drilling. The invention of the non-disperse low-solid-content PDF in the 1960s shows that PDF technology has entered the stage of scientific development, and until now, its development has generally experienced five stages: beginning, developing, improving, re-developing, and re-improving. Dozens of polymer additives and PDF systems have been invented and applied, which have solved severe drilling problems, greatly improved drilling efficiency, and promoted exploration and development in difficult oil and gas resources. This paper first reviews the research progress of PDF technology according to the timeline by introducing the composition, feature, advantages, and disadvantages of some representative polymer additives and PDF systems, emphatically the function and mechanism of stabilizing wellbores, lubricating drilling tools, and protecting reservoirs of the biomimetic wellbore-strengthening PDF and amphiphobic high-efficiency PDF in unconventional gas drilling. Then, combining future global demands, especially China’s strategic needs of oil and gas exploration and development, the development tendency of PDF technology is critically illustrated by introducing several potential research directions including intelligent PDF, ecological PDF, and PDF for natural gas hydrate and deep layer gas resources