Nondestructive measurement of water content and moisture migration of unsaturated red clays in South China

To reveal the moisture migration mechanism of the unsaturated red clays, which are sensitive to water content change and widely distributed in South China, and then rationally use them as a filling material for highway embankments, a method to measure the water content of red clay cylinders using X-ray computed tomography (CT) was proposed and verified. Then, studies on the moisture migrations in the red clays under the rainfall and ground water level were performed at different degrees of compaction. The results show that the relationship between dry density, water content, and CT value determined from X-ray CT tests can be used to nondestructively measure the water content of red clay cylinders at different migration time, which avoids the error reduced by the sample-to-sample variation. The rainfall, ground water level, and degree of compaction are factors that can significantly affect the moisture migration distance and migration rate. Some techniques, such as lowering groundwater table and increasing degree of compaction of the red clays, can be used to prevent or delay the moisture migration in highway embankments filled with red clays

Research on the Construction of Chinese Song Hierarchical Database Oriented to Chinese Teaching

As a critical auxiliary method in teaching Chinese as a foreign language, Chinese songs have the characteristics of a strong sense of rhythm, extensive vocabulary, and rich cultural knowledge. Previous studies have mostly discussed the use of Chinese songs in Chinese teaching from the perspective of teaching methods, teaching experiment design and textbooks. There is no specific research on the construction of a database of Chinese song ratings for Chinese learners of different levels. Based on Internet resources, this study collected 9098 Chinese song lyrics and built a database. Based on the analysis of the characteristic data in the database and the method of building a vector space model, four songs of different difficulty levels were divided, which was respectively targeted at Chinese learners of different levels. This research can reduce Chinese teachers 'lesson preparation time and improve teachers' teaching efficiency

Effect of Forage Brassica on Subsequent Soil Water Content and Yield of Dual-Purpose Winter Wheat in Rainfed Region of Northwestern China

The dual-purpose performance of winter wheat used for both forage and grain production has been explored as an alternative practice for filling the feed gap during winter and spring in agricultural areas of the Loess Plateau. Profit-ability is still restricted however, because of a three month summer fallow period between harvest and planting of the subsequent wheat crop. During this 3 month period 60% of the annual precipitation occurs, limiting the effective use of soil water and compounding the risk of soil erosion. Thus it is important to cultivate some forage crops with higher water consumption, protecting the ecological environment during this period and enlarging the forage resource base through their high forage yield and good quality. A previous study has shown that inclusion of rapeseed into crop rotations could reduce disease in subsequent plantings, leading to an increase in production of the following wheat crop (Brendan and John 2004). Accordingly, dual-purpose winter wheat after forage brassica may be an effective option to meet these requirements. Other studies have shown however, that wheat yield of grazed plots following brassica was reduced by 29% compared with that of grazed plots following fallow, and that average grain yield in grazed plots was reduced by 38% compared with that in ungrazed plots (Kelman and Dove 2007). Additionally, the possibility of severe water stress occurring after forage crop harvest is an important concern. In this study, soil moisture status and forage and grain yield of dual-purpose winter wheat following forage brassica were investigated and compared with those of winter wheat after fallow

Rac1 activation induces tumour necrosis factor-α expression and cardiac dysfunction in endotoxemia

Induction of tumour necrosis factor-α (TNF-α) expression leads to myocardial depression during sepsis. However, the underlying molecular mechanisms are not fully understood. The aim of this study was to investigate the role of Rac1 in TNF-α expression and cardiac dysfunction during endotoxemia and to determine the involvement of phosphoinositide-3 kinase (PI3K) in lipopolysaccharide (LPS)-induced Rac1 activation. Our results showed that LPS-induced Rac1 activation and TNF-α expression in cultured neonatal mouse cardiomyocytes. The response was inhibited in Rac1 deficient cardiomyocytes or by a dominant-negative Rac1 (Rac1N17). To determine whether PI3K regulates Rac1 activation, cardiomyocytes were treated with LY294002, a PI3K selective inhibitor. Treatment with LY294002 decreased Rac1 activity as well as TNF-α expression stimulated by LPS. Furthermore, inhibition of PI3K and Rac1 activity decreased LPS-induced superoxide generation which was associated with a significant reduction in ERK1/2 phosphorylation. To investigate the role of Rac1 in myocardial depression during endotoxemiain vivo, wild-type and cardiomyocyte-specific Rac1 deficient mice were treated with LPS (2 mg/kg, i.p.). Deficiency in Rac1 significantly decreased myocardial TNF-α expression and improved cardiac function during endotoxemia. We conclude that PI3K-mediated Rac1 activation is required for induction of TNF-α expression in cardiomyocytes and cardiac dysfunction during endotoxemia. The effect of Rac1 on TNF-α expression seems to be mediated by increased NADPH oxidase activity and ERK1/2 phosphorylation. © 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd

Spatiotemporal variation characteristics of hourly soil temperature in different layers in the low-latitude plateau of China

Soil temperature change has considerable impact on land surface energy and water balances, and hence on changes in weather/climate, surface/subsurface hydrology, and ecosystems. However, little is known regarding the spatiotemporal variations and influencing factors of changes in hourly soil temperature (depth: 5–320 cm) in low-latitude highland areas. This study analyzed the hourly soil temperature at each hour during 2004–2020 and at 08:00, 14:00, and 20:00 (Beijing Time) during 1961–2020. The results revealed the following. 1) As soil depth increased, average soil temperature increased in autumn and winter, and decreased annually and in spring and summer. It exhibited significant increase during 00:00–23:00 annually, seasonally, and monthly, especially at depths of 40–320 cm during 2004–2020. Average soil temperature increased at 08:00 and decreased at 14:00 and 20:00 with increasing soil depth, but the opposite trend was found annually, seasonally, and monthly at 08:00, 14:00, and 20:00 during 1961–2020. 2) With increasing elevation, average soil temperature decreased at 08:00, 14:00, and 20:00 at depths of 5–20 cm, and showed significant increase trend at 08:00 and 14:00 at depths of 10–20 cm (except at 14:00 at 10-cm depth). 3) At 5-cm depth, the critical accumulated soil temperature of ≥12°C and 14°C extended the potential growing season during 1961–2020. 5) Significant uptrend of hourly soil temperature annually, seasonally, and monthly potentially leads to additional release of carbon to the atmosphere and increased soil respiration, reinforcing climate warming. These findings contribute to better understanding of the variation of shallow soil temperatures and land–atmosphere interactions in low-latitude highland areas